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Dinophysiales (Dinophyceae) of the National Park Sistema Arrecifal Veracruzano, Gulf of Mexico, with a key for identification.

INTRODUCTION

The order Dinophysiales with about 280 species (Gomez et al., 2011a) is monophyletic (Saldarriaga et al., 2004) and morphologically well distinguished by a sagittal suture encircling the entire cell. The order is represented by only three families, Dinophysiaceae F. Stein, Amphisoleniaceae Lindemann and Oxyphysiaceae Sournia, which comprise 13-14, 2 and 1 recent genera, respectively (Fensome et al., 1993). Most genera and species are marine planktonic; however, a typically benthic/ epiphytic Sinophysis Nie et Wang is also known from the sea. Some genera such as Citharistes F. Stein and Histioneis F. Stein, and possibly Ornithocercus F. Stein, Amphisolenia F. Stein and Triposolenia Kof., prefer oceanic waters (Okolodkov, 2011). The highest generic and species diversities are found in tropical seas. Dinophysis Ehrenberg sensu lato is the most common genus, distributed throughout all the oceans including both polar regions, with the largest number of species. Recently described small cells in about a dozen Dinophysis species, responsible for infraspecific morphological variability (dimorphism), are believed to be gametes in a three-looped life-history pattern, which consists of sexual, small/intermediate cell and vegetative cell cycles (Hansen, 1993; Reguera et al., 1995, 2007, 2012; Reguera & Gonzalez- Gil, 2001; Reguera, 2002). Pellicle cysts, more frequently and misleadingly called temporary cysts in the literature, are not known for any of the Dinophysiales genera (Bravo et al., 2009). Resting (hypnozygotic) cysts are reliably known for Dinophysis acuta Ehrenb. and D. tripos Gourret (Cannon, 1993; Moita & Sampayo, 1993; Head, 1996). Most Dinophysiales are heterotrophic and are known to feed by myzocytosis with a peduncle (Elbrachter, 1991). Plastids of photosynthetic species have predominantly a cryptophyte origin (Lucas & Vesk, 1990). The genera Ornithocercus, Citharistes, Histioneis, Amphisolenia and Triposolenia may have cyanobacteria symbionts, extracellular (the former three genera) or intracellular (the latter two), belonging to the genera Synechococcus Nageli and Synechocystis Sauvageau, sometimes called phaeosomes (Norris, 1967; Taylor, 1982; Hallegraeff & Jeffrey, 1984; Lucas, 1991; Fensome et al., 1993; Gordon et al., 1994; Carpenter, 2002; Handy et al., 2009).

Twelve Dinophysis species are known to be causative agents of diarrheic shellfish poisoning due to accumulation of toxins (okadaic acid, dinophysistoxin-1 and -2, and pectenotoxin-2). In 2008, a bloom caused by Dinophysis species, primarily by D. ovum (also reported as D. cf. ovum or the Dinophysis acuminata complex), was detected in Texas coastal waters, the western Gulf of Mexico, along with the presence of okadaic acid (Campbell et al., 2010; Swanson et al., 2010; Fux et al., 2011). This was the first record of toxicity caused by Dinophysis species in North American shellfish; it had been previously recorded in some areas in Europe and Asia (Hess & Nicolau, 2010). Recent advances in the understanding of the physiology (including toxicity), ecology and evolution of the Dinophysiales species are and will be related to the success in culturing Dinophysis species in a three-stage system involving (1) cultivation of cryptophytes, (2) feeding them to ciliate prey Myrionecta rubra (Lohmann) Jankowski, and (3) feeding of the latter to the Dinophysis cells (Park et al., 2006; Nishitani et al., 2008; Tong et al., 2010).

Molecular studies (rRNA gene sequences) of the species of the family Dinophysiaceae showed separation between the genera Dinophysis sensu stricto and Phalacroma F. Stein and a closer affinity of the former to Ornithocercus and Histioneis than to Phalacroma (Handy et al., 2009; Jensen & Daugbjerg, 2009; Gomez et al., 2011b). Chlorophyll-containing Dinophysis species form a separate clade, and the species hitherto ascribed to the genus Phalacroma belong to different clades (Gomez et al., 2011a). In addition, the only benthic dinophysioid genus, Sinophysis, and a planktonic genus, Pseudophalacroma Jorg. ex Lebour, were supposedly divergent with respect to the typical dinophysioid dinoflagellates (Dinophysiales sensu stricto), suggesting that dinophysioid dinoflagellates as a whole might not form a monophyletic group (Gomez et al., 2012). However, this requires more molecular evidence.

In the most recent checklist of dinoflagellates of the Gulf of Mexico, Steidinger et al. (2009) mentioned 136 species distributed between the families Dinophysiaceae (111, including two Citharistes species), Amphisoleniaceae (24) and Oxyphysiaceae (1). Unlike these authors, who considered the family Oxytoxaceae belonging to the Dinophysiales, I follow the classification of Fensome et al. (1993), who ascribe this family to the order Gonyaulacales. Similarly, Citharistaceae is not separated here as a family. Norris (1969) documented nine Histioneis and seven Ornithocercus species from the southeastern Gulf of Mexico with line drawings. Licea et al. (2004) gave the names of 42 species of Dinophysiaceae (including two Citharistes species), eight Amphisoleniaceae and one Oxyphysiaceae species for the southern Gulf of Mexico. Parra-Toriz et al. (2011) mentioned 44 species from the order Dinophysiales found in the southwestern Gulf of Mexico without giving the species names.

In the State of Veracruz, 39 Dinophysiales species have been found previously (Avendano-Sanchez & Sotomayor-Navarro, 1982; Hernandez-Mendiola, 1988; Suchil-Vilchis, 1990; Zamudio-Resendiz, 1998; Aquino-Cruz, 2002; Garcia- Resendiz, 2003; Legaria-Moreno, 2003; Estradas-Romero, 2004; Okolodkov et al., 2007, 2011; Parra-Toriz et al., 2011). Zamudio-Resendiz (1998) mentioned 20 Dinophysiales species names; however, she did not give separate species lists for the State of Tamaulipas and the State of Veracruz. Nevertheless, her data are considered in the present article as they all were for Veracruz. In contrast, the article by Licea et al. (2004) was omitted because their records are related to the southern Gulf of Mexico as a whole. For the National Park Sistema Arrecifal Veracruzano (NPSAV), in total, 22 planktonic Dinophysiales species have been reported (Okolodkov et al., 2011; Parra-Toriz et al., 2011); however, only six of them were documented by photographs. In addition, three epiphytic Sinophysis species were encountered and photographed (Okolodkov et al., 2007). In general, the species richness of the Dinophysiales in the NPSAV was considered to be very low (Parra-Toriz et al., 2011).

To fill this gap and to document the Dinophysiales species, both planktonic and benthic (epiphytic), found in the NPSAV, and to provide a key for their identification were the goals of the present study.

MATERIAL AND METHODS

Phytoplankton samples were taken weekly with a hand net, 20 [micron]m mesh and 30 cm mouth diameter, from 27 sites (stations) throughout the National Park Sistema Arrecifal Veracruzano, southwestern Gulf of Mexico. Collections were made almost every week during the period from May 2005 through April 2008 as part of the monitoring program of the Aquarium of Veracruz (AVM), and two monthly monitoring programs were performed by ICIMAP-UV, from September 2006 through September 2007 (CEP-I), and from April 2007 through May 2008 (CEP-II; Fig. 1, Table 1). Site depths ranged from 1.5 m to 34 m. At each station the net was towed horizontally for 5 min. at the velocity of the boat of ca. 2.5 knots to sample a superficial 30-cm layer. The samples were fixed with a stock formaldehyde solution to a final concentration of 4% and stored in 100-ml dark plastic bottles. To contrast the cells for an easier search and better photographs, a 0.2% Trypan Blue water solution was added to water mounts (Lebour, 1925; Taylor, 1978). About 700 samples were analyzed using a Nikon TS100 and an Olympus CKX41 inverted microscope for a Sedgwick-Rafter 1-ml chamber and an Olympus BX51 compound microscope for water mounts. The information about sampling and the laboratory analysis of benthic/epiphytic dinoflagellates was published earlier in detail (Okolodkov et al., 2007). For this study, only Sinophysis species were included, and they were sampled from both seaweeds and seagrasses growing on the sea bottom at St. 3 and 5, and at St. 2 from seaweeds attached to a plastic anchored buoy and its line, in the Aquarium of Veracruz monitoring. The cells were photographed mainly with an Olympus C7070 digital camera (Pl. 1-6). Some samples were examined in a JEOL JSM-7600F scanning electron microscope (SEM) at a working distance of 15 to 21 mm and a voltage of 1.2 to 5.0 kV after a preliminary wash in distilled water, followed by dehydration in a series of ethanol solutions of increasing concentration (30, 50, 70, 90 and 100%), air drying on 0.5" aluminium mounts and sputter coating with gold-palladium using a Polaron SC7640 High Resolution Sputter Coater (Quorum Technologies, Newhaven, East Sussex, U. K.); some micrographs were obtained using a Philips XL-30 environmental SEM (Pl. 7 and 8). Line drawings were made from digital images (Pl. 10-13).

About 90 publications, abstracts and theses on the phytoplankton and dinoflagellates of the Gulf of Mexico were examined, with special emphasis on the state of Veracruz. Extensive old and new literature containing illustrations was analyzed and cited. The works where the species are illustrated are marked with asterisks: an asterisk (*) indicates line drawings, two asterisks (**) indicate light micrographs, and three asterisks (***) indicate scanning electron micrographs. Relative abundance was given according to the following criteria: extremely rare--found in <1% of the analyzed samples only occasionally (less than 25 cells were found in total), rare--encountered in 1 to 10% of the samples as rare cells, common--seen in 11 to 50% of the samples (normally as dozens of cells in a Sedgwick-Rafter chamber), and very common--found in >50% of the samples (dozens or hundreds of cells per chamber). Abbreviations of authors of scientific names are used according to Brummitt & Powell (1992), unless they are not listed in the book.

The abbreviations for cell measurements are as follows: Lb--body length measured from the furthest part of the epitheca to the antapex of the hypotheca, not considering appendages or processes (lists or spines); Lt--total length measured from the furthest part of the epitheca or the anterior cingular list to the furthest part of the posterior or posterior-lateral processes or lists; Db--maximum cell body depth measured in its widest part in lateral view, not considering the sulcal or cingular lists; Dt--total depth, considering the sulcal and/or cingular lists. Sometimes the cell body width (W) was measured in ventral or dorsal view. All the measurements were performed using the 40x objective to maximize accuracy. To facilitate identification, the terminology is given (Pl. 7 and 8). Other abbreviations are: ACL--anterior cingular list; LSL--left sulcal list; PCL--posterior cingular list; R1--first rib, R2--second rib, R3--third rib; RSL--right sulcal list.

RESULTS

Below, the keys for identification of eight genera and 38 Dinophysiales species are presented, along with descriptions, light and scanning electron microscope photographs and line drawings.

Key for identification of the genera of Dinophysiales

1a Cells are very long and thin, with tiny epitheca and
elongated hypotheca swollen in its anterior or middle part,
with undeveloped sulcal lists (I) Amphisolenia

1b Cells are not long and thin, normally with well
developed sulcal lists

2a Cells with elaborate left sulcal list (LSL), extending to
the antapex or even onto the dorsal side of the hypotheca

2b Cells with poorly elaborate LSL not reaching the antapex

3a Cells usually kidney-shaped or suboval in lateral view,
with high posterior cingular list (PCL), which forms a cylindrical
basket supported by longitudinally oriented ribs, and a funnel-shaped
anterior cingular list (ACL) (V) Histioneis

3b Cells usually subglobular in lateral view, with relatively
low cingular lists (VI) Ornithocercus

4a Epitheca very small and narrow, button-like, LSL without
supporting ribs (VIII) Sinophysis

4b Epitheca reduced but wide, LSL with supporting ribs

5 a Epitheca low, usually with ACL located mainly in
front of it (II) Dinophysis

5b Epitheca relatively high, with ACL located behind it

6a LSL with a second (fission) rib (R2), the apical pore
located close to the cingulum
(VII) Phalacroma

6b LSL without R2, the apical pore shifted to the cell apex

7a LSL about 0.75-1.0 hypotheca length, the cingulum with
two rows of pores (III) Heteroschisma

7b LSL about 0.4-0.5 hypotheca length, the cingulum with
one row of pores (IV) Pseudophalacroma

I. Genus Amphisolenia F. Stein

Key for identification of Amphisolenia species

1a Cells with bifurcated hypotheca (1) Amphisolenia bifurcata

1b Cells not bifurcated

2a Cells inflated in their anterior part, with a subterminal
spinule at elbow (2) Amphisolenia bidentata

2b Cells inflated in their middle part, with no subterminal
spine at elbow

3a Cells straight, with four antapical spinules (3)
Amphisolenia schauinslandii

3b Cells sigmoid in their posterior part, with
two antapical spinules (4) Amphisolenia schroederi


1. Amphisolenia bifurcata G. Murray et Whitting, 1899 (Pl. 1, Fig. 1 and 2; Pl. 10, Fig. 1 and 2).

Cells very long and thin, with a thin "neck", in lateral view slightly inflated in the anterior third (midbody), continuously tapering into a long "tail" (also called caudal appendix or caudal pedunculum; see Balech, 1988: 69), bifurcating at the distal third part of the cell into two asymmetric branch-like processes that form an angle of ca. 45[degrees] between their proximal parts and are parallel or almost parallel between their distal portions directed straight back. These caudal processes are subequal in size, widest and most curved in their middle parts; however, the lower one is slightly longer and thicker. Both processes are slightly swollen in the middle, bearing a subterminal spinule at elbow and terminated with three spinules, positioned on slightly widened tips. The terminal portions of the caudal appendices are slightly thickened toward the end. The anterior half of the cell, in general, is similar to that in A. bidentata; however, the midbody is wider. Lt 975-995 [micron]m (981.4 [+ o -] 6.3 pm), W 35-45 [micron]m (42.0 [+ o -] 4.7 [micron]m), the caudal appendices span 97-110 [micron]m (103.4 [+ o -] 5.0 pm); n=7.

Records in the State of Veracruz: Zamudio-Resendiz, 1998; Okolodkov et al., 2011. Extremely rare in NPSAV; the species was found only on 1 March 2008 at St. 4 and 6 (CEP-II).

References: Murray & Whitting, 1899 *: 331, pl. 31, fig. 1a-d; Kofoid & Skogsberg, 1928 *: 432, fig. 56(6), pl. 12, fig. 1, 3, 5; Schiller, 1933*: 182, fig. 174 (after Kofoid & Skogsberg, 1928); Balech, 1962 *: 134, pl. 18, fig. 276; Steidinger & Williams, 1970 **: pl. 2, fig. 6; Tester & Steidinger, 1979 **: 27, fig. 55.

2. Amphisolenia bidentata Schrod., 1900 (Pl. 1, Fig. 3-5; Pl. 10, Fig. 3 and 4).

Cells very long and thin, slightly sigmoid, with a thin "neck", in lateral view slightly inflated in the anterior quarter (midbody), continuously tapering into a long "tail", which is slightly curved upward and terminated with three spinules, one of which (subterminal, located at elbow) faces downward and the other two (terminal, located symmetrically on both sides of the "tail") upward; distal part of the "tail" is slightly widened, truncate and dorsoventrally compressed. The "head" is small, consisting of the epitheca and the cingulum, is positioned obliquely in relation to the longitudinal axis of the cell, looking anteriorly-upward. The epitheca is slightly convex, separated from the cingulum by a rather wide list supported by several ribs. PCL continues into the sulcal lists along both sides of the "neck", reaching the "midbody", where it is widest. Lt 800-870 [micron]m (851.2 [+ o -] 15.6 [micron]m), W 15-24 [micron]m (19.1 [+ o -] 2.4 pm); n=39.

Morphological note. A specimen 640 [micron]m long and 20 [micron]m wide, with a gradually tapering hypotheca ending with a thin theca with an acute end without spines, presumably belonging to A. bidentata (Pl. 1, Fig. 5), was found at St. 4 on 1 March 2008 (CEP-II).

Records in the State of Veracruz: Zamudio-Resendiz, 1998; Figueroa-Torres & Weiss-Martinez, 1999; Aquino-Cruz, 2002**; Okolodkov et al., 2011. Rare in NPSAV (Feb., March, May, July, Dec.); the most common species of the genus Amphisolenia in the study area.

References: Schroder, 1900 *: 20, 35, pl. 1, fig. 16a, c; Kofoid & Skogsberg, 1928 *: 409, fig. 54(1-4), 55, 56(1); Schiller, 1933 *: 178, fig. 169a-e (after Kofoid & Skogsberg, 1928); Rampi, 1940 *: 24, fig. 44; Silva, 1955 *: 124, pl. 2, fig. 1- 4; Yamaji, 1966 *: 72, pl. 33, fig. 11; Halim, 1967 **: 704, pl. 1, fig. 2, pl. 2, fig. 15; Steidinger et al., 1967 *: pl. 2, fig. a; Wood, 1968 *: 18, fig. 19; Steidinger & Tangen, 1996 *: 426, pl. 10; Steidinger & Williams, 1970 **: pl. 2, fig. 5; Taylor, 1976 *: 28, pl. 2, fig. 21, 22, pl. 3, fig. 21b, 22b; Balech, 1977*: 26, fig. 1-14, 1988 *: 69, pl. 17, fig. 2, 3, 13; Pesantes-Santana, 1978 *: 6, pl. 1, fig. 4-7; Tester & Steidinger, 1979 **: 27, fig. 54; Hernandez-Becerril, 1988a **: 188, pl. 1, fig. 1-3; 1988b **: 10, fig. 52, 53; Licea et al., 1995* ***: 17, pl. 1, fig. 2a-c, pl. 17, fig. 3; Hernandez-Becerril et al., 2008 **: 10, fig. 52, 53; Esqueda-Lara & Hernandez-Becerril, 2010**: 170, fig. 163a-d.

3. Amphisolenia schauinslandii Lemmermann, 1899 (Pl. 1, Fig. 6 and 7; Pl. 7, Fig. 1 and 2; Pl. 10, Fig. 5 and 6).

Cells long and thin, fusiform, with a thin "neck" and a straight hypotheca, in lateral view inflated in its middle part (midbody), gradually diminishing backward and only slightly widening at the truncate posterior end and bearing four spinules, directed posteriorly and almost equally distanced. Lt 415-440 [micron]m (427.5 [+ o -] 17.7 [micron]m), W 20-25 [micron]m (22.5 [+ o -] 3.5 [micron]m); n=2.

Records in the State of Veracruz: Okolodkov et al., 2011. Extremely rare in NPSAV; two cells were found on 1 March 2008 at St. 4 and 6 (CEP-II). This is the first documented record of this species, not considering A. cf. schauinslandi mentioned by Zamudio-Resendiz (1998).

References: Lemmermann, 1899*: 350, pl. 1, fig. 18, 19; Kofoid & Skogsberg, 1928*: 374, fig. 49(4), pl. 7, fig. 1-8; Schiller, 1933*: 169, fig. 155; Wood, 1968*: 21, fig. 31; Balech, 1988*: 71, pl. 17, fig. 9-11.

4. Amphisolenia schroederi Kof., 1907 (Pl. 1, Fig. 8 and 9; Pl. 10, Fig. 7 and 8).

Cells long and thin, fusiform, with a thin "neck" and slightly sigmoid posterior part of the hypotheca, in lateral view inflated in its middle part (midbody), gradually diminishing backward, bearing two terminal spinules at the antapex, directed posteriorly. Lt 312 [micron]m, W 19 [micron]m; n=1.

Morphological note. The specimen from Veracruz is also similar to A. curvata Kof., 1907 by the swelling in the middle of the cell, the presence of two terminal spinules, and curved posterior end of the cell. However, in A. curvata the "tail" is gradually curved to the dorsal side of the cell, and in A. schroederi the curvature is sigmoid and not so pronounced. Unlike the figures by Kofoid (1907) and Taylor (1976), who pictured the cells with a less clearly differentiated midbody, our specimen has a midbody much more differentiated from the rest of the cell. Our cell is quite different in a number of features from the specimen of A. schroederi illustrated and described by Balech (1962).

The first reliable record for the State of Veracruz. Extremely rare in NPSAV; the only cell was found on 26 October 2006 at St. 3 (AVM). It is the second record of this species in the Gulf of Mexico. Previously it was observed only at one (unknown) sampling site in the southern Gulf of Mexico (Licea et al., 2004) and also by Balech (1967b).

References: Kofoid, 1907*: 201, pl. 13, fig. 81; Kofoid & Skogsberg, 1928*: 400, fig. 49(15), pl. 10, fig. 2-4; Schiller, 1933*: 176, fig. 165; Balech, 1962*: 132, pl. 18, fig. 271.

II. Genus Dinophysis Ehrenberg

Key for identification of Dinophysis species

1a Cells with one antapical spine

1b Cells without antapical spine

2a Cells small, 40-50 [micron]m long, with strongly areolated
theca, subtriangular hypotheca and a short antapical spine (1)
Dinophysis capitulata

2b Cells medium-sized, 60-100 [micron]m long, suboval,
with smooth theca and relatively
long antapical spine (2) Dinophysis hastata

3a Cells with a conical projection directed
posteriorly-ventrally (3) Dinophysis caudata

3b Cells without posterior projection

4a Cells strongly elongated, with nearly straight ventral margin
in lateral view, narrowly rounded posterior part of the hypotheca
and a long LSL almost equal to the cell body length (4)
Dinophysis schroederi

4b Cells oval or suboval in lateral view, with convex ventral
margin, widely rounded posterior part of the hypotheca and LSL
of about 0.65-0.70 the cell body length

5a Distance between R2 and R3 is about twice that between
R1 and R2, with no list behind R3 (5) Dinophysis cf. similis

5b R1, R2 and R3 equally or subequally distanced, a
list is present behind R3

6a Cells medium-sized, 45-60 [micron]m long, with areolated
thecae, LSL having the same width in its anterior and
posterior parts (6) Dinophysis ovum

6b Cells small, 28-38 [micron]m long, with smooth thecae, LSL
increasing in width from R1 backward (7) Dinophysis cf. exigua


1. Dinophysis capitulata Balech, 1967 (Pl. 2, Fig. 1; Pl. 10, Fig. 9).

Cells subtriangular, strawberry-shaped, usually with a posteriorly attenuated hypotheca, terminating with a coarse triangular or subtriangular spine. In apical view, cells are almost circular. The theca is coarsely areolated. The cell is widest at the level of PCL. The cingulum is noticeably concave. The cingular lists are directed more laterally than anteriorly, supported by numerous coarse ribs that reach only the mid-width of the lists. The sulcal lists are moderately wide. The distance between R2 and R3 is slightly longer than between R1 and R2. R3 is the thickest, straight or somewhat curved, slightly longer than R2. RSL continues well behind the base of R2 but does not reach R3. Lb 37.5-42.5 [micron]m (40.0 [+ o -] 1.8 [micron]m), Lt 42.5-50 [micron]m (44.5 [+ o -] 2.5 pm), Db 33.5-41.5 [micron]m (36.7 [+ o -] 2.1 [micron]m), Dt 40-47.5 [micron]m (42.7 [+ o -] 2.3 [micron]m); n=14.

A new record for the southern Gulf of Mexico and the second known record for the entire Gulf (see Steidinger et al., 2009). Rare in NPSAV (Apr., Oct.).

References: Balech, 1967a*: 90, pl. 2, fig. 25-31; 1988*: 56, pl. 14, fig. 1-3.

2. Dinophysis hastata F. Stein, 1883 (Pl. 2, Fig. 2 and 3; Pl. 10, Fig. 10). Syn.: D. odiosa (Pavill.) L. S. Tai et Skogsb., 1934: 448; (?) Phalacroma hastatum Pavill., 1909: 283, fig. 4.

Cells are irregularly ovoid or sometimes regularly ovoid, with a subtruncate anterior end and broadly or narrowly rounded posterior end, terminated with a strong triangular antapical spine directed posteriorly-ventrally or in rare cases backward, often supported by a thick central rib. The cell is widest at the level of R3. Epitheca is very short, flat or slightly convex. The hypotheca is slightly asymmetrical in relation to the longitudinal axis of the cell, more narrowly rounded than the epitheca. The cingulum is slightly convex. The cingular lists are wide, directed laterally-anteriorly; ACL is supported by numerous ribs. R1, R2 and R3 are equally spaced or with the longer distance between R2 and R3 (up to 1.5 times the distance between R1 and R2). R3 is the longest and the thickest, almost straight or slightly curved backward, almost reaching the level of the antapex. LSL is wide, often finely reticulate, RSL terminates at R3. Lb 45-67.5 [micron]m (52.6 [+ o -] 9.8 [micron]m), Lt 60- 100 [micron]m (71.0 [+ o -] 14.0 gm), Db 36.5-57.5 [micron]m (44.4 [+ o -] 8.4 [micron]m), Dt 47.5-82.5 [micron]m (59.0 [+ o -] 13.4 [micron]m); n=18.

Taxonomic note. Judging from the wide morphological variation and the recently published data on molecular biology, it is a collective species, or the Dinophysis hastata group (also called the "hastata" group), hiding a number of cryptic species (Kofoid & Skogsberg, 1928: 266; Abe, 1967a: 77; Balech, 1967a: 282; Norris & Berner Jr., 1970: 169; Gomez et al., 2011a: 404); the "hastata" group includes at least 21 species (Norris & Berner Jr., 1970: 146). Based on the material from the NPSAV, variation is most visible in cell shape, the position and shape of the antapical spine, length and direction of R3, the distance between R2 and R3 and the longitudinal expansion of LSL. Halim (1967: 726, pl. 4, fig. 47) presented D. hastata under the name of D. monacantha Kof. et Skogsb., which I consider a misidentification. The diagnosis of the latter includes the statement about the cell shape: "body rounded trapeziform in lateral outline, deepest in or just behind the middle" (Kofoid & Skogsberg, 1928: 283, 37(2, 3); that does not correspond to the specimen illustrated by Halim (1967), which is suboval and almost symmetrical in relation to the longitudinal axis of the cell.

Records in the State of Veracruz: Avendano-Sanchez & Sotomayor-Navarro, 1982; Zamudio-Resendiz, 1998; Okolodkov et al., 2011. Extremely rare in NPSAV; the species was found only on 26 October 2006 at St. 3 (AVM).

References: Stein, 1883*: pl. 19, fig. 12; Paulsen, 1908*: 13, fig. 9 (after Stein, 1883); Lebour, 1925*: 83, fig. 21e (after Stein, 1883); Kofoid & Skogsberg, 1928*: 261, fig. 32(1-17), 33(1-3); Schiller, 1933*: 138, fig. 131a-f; Bohm, 1936*: 18, fig. 6a-h; Rampi, 1940*: 22, fig. 40; Silva, 1956*: 17, pl. 1, fig. 26, 27 (as D. diegensia); Yamaji, 1966*: 71, pl. 32, fig. 17; Abe, 1967a*: 76, fig. 25; Halim, 1967**: 726 (misidentified as D. monacantha); Norris & Berner Jr., 1970*: 165, fig. 46-59; Steidinger & Williams, 1970**: pl. 17, fig. 48; Taylor, 1976*: 37, pl. 5, fig. 52-55; Dodge, 1982* ***: 49, fig. 4C, pl. 2, fig. g; 1985***: 21; Balech, 1988*: 54, pl. 13, fig. 1- 3; Hallegraeff & Lucas, 1988***: fig. 11, 15, 16, 26b; Steidinger & Tangen, 1996*: 433, pl. 12; Hansen et al., 2001**: 29, pl. 2, fig. A; Larsen & Nguyen, 2004**: 67, pl. 2, fig. 1-2; Hernandez-Becerril et al., 2008**: 6, fig. 15; Esqueda-Lara & HernandezBecerril, 2010**: 151, fig. 144a-c.

3a. Dinophysis caudata Saville-Kent, 1881 var. pedunculata (Schmidt) Schrod., 1906 (Pl. 2, Fig. 4; Pl. 7, Fig. 3; Pl. 10, Fig. 11). Syn.: D. homunculusF. Stein, 1883, pro parte: 24, pl. 21, fig. 8; Dinophysis diegensis Kof., 1907 (Univ. Calif. Publ. Zool. 3, 13): 313, pl. 33, fig. 57-61; Dinophysis diegensisf. contracta J. Schill., 1933: 152, fig. 144d.

Cells are irregularly trapezoidal, angulated, with a well separated hypothecal pointed conical projection directed posteriorly-ventrally, up to 0.4 of the body length, which can bear 1 to 3 knob-like spinules. The dorsal contour is straight or slightly concave along the anterior part of the hypotheca and convex along its middle part. The ventral contour is straight in general, slightly undulate. The cell is widest at the base of R3, distinctly tapering anteriorly. The theca is coarsely areolated. The cingulum is noticeably concave. The cingular lists are directed laterally- anteriorly and supported by ribs. The sulcal lists are wide, often reticulate. The LSL is wide and relatively long, supported by three long, slightly curved ribs spaced equally apart; R3 is the longest. The distal margins of the LSL form almost a right angle. The RSL is wedge-shaped, terminating at R3 and being very narrow between R2 and R3. Paired cells resulting from binary fission (asexual reproduction) are common. Lb 77.5-90 [micron]m (86.8 [+ o -] 3.3 [micron]m), Lt 85-101 [micron]m (96.9 [+ o -] 4.0 [micron]m), Db 42.5-48.5 [micron]m (46.2 [+ o -] 1.6 [micron]m), Dt 52.5-68.5 [micron]m 63.1 [+ o -] 3.8 [micron]m); n=31.

Morphological note. Three gametes, previously known as Dinophysis diegensis Kof., were observed: small cells, Lb 55-62.5 [micron]m (57.8 [+ o -] 4.1 [micron]m), Lt 62.5-71 [micron]m (65.3 [+ o -] 4.9 [micron]m), Db 26-30 [micron]m (27.8 [+ o -] 2.0 [micron]m), Dt 35.7 [+ o -] 2.9 (Pl. 2, Fig. 7 and 8). Earlier it was hypothesized (Moita & Sampayo, 1993; Reguera et al., 1995; Reguera & Gonzalez-Gil, 2001) and experimentally shown (Reguera et al., 2007) that D. diegensis and D. caudata are synonymous. Gametes had slightly tapering anterior sides, pointed posteriorly, without a hypothecal projection or with a well marked tubular process of up to 0.25 of the cell body length, with the longest R1 and narrower sulcal lists. Dinophysis caudata is a rather variable species, which resulted in the description of a number of forms and varieties. I follow Balech's (1951) opinion, distinguishing only var. pedunculata and var. abbreviata within D. caudata.

Records in the State of Veracruz: Avendano-Sanchez & Sotomayor-Navarro, 1982 (as D. homunculus); Suchil-Vilchis, 1990*; Zamudio-Resendiz, 1998 (also, as D. diegensis Kof.); Figueroa-Torres & Weiss-Martinez, 1999; Aquino-Cruz, 2002* **; Estradas-Romero, 2004; Tejeda-Hernandez, 2005**; Hernandez-Becerril et al., 2008; Okolodkov et al., 2011. In NPSAV it is the most common species of the genus Dinophysis. It was observed throughout the year.

References: Stein, 1883*: pl. 21, fig. 1, 2, 5, non 3, 4, 6-8 (as D. homunculus); Paulsen, 1908*: 19, fig. 20 (left, not right; after Stein, 1883; as D. homunculu$; 1931*: 34, fig. 19; Pavillard, 1916*: 56, fig. 15A (as D. homunculus type), 57, pl. 3, fig. 2 (as D. diegensis Kof. var. caudata nov. var.); Lebour, 1925*: 82, fig. 21c; Martin, 1929*: 21, pl. 4, fig. 14; Tai & Skogsberg, 1934*: 453, fig. 9A-K, 10D-F; Curl, 1959*: 305, fig. 110 (erroneously written as 100 on p. 320); Bohm, 1935*: 277, fig. 4a-i; 1936*: 20, fig. 7a-c; Rampi, 1940*: 23, fig. 41; Balech, 1951*: 6, pl. 1, fig. 1, 10, pl. 3, fig. 45-68, pl. 4, fig. 73-76; Yamaji, 1966*: 70, pl. 32, fig. 13 and 14 (as D. homunculus and D. homunculus f. pedunculatusSchmidt; also, as D. diegens Kofoid and D. diegens Kofoid var. caudata Pavillard, both misspelled); Halim, 1967**: 726, pl. 4, fig. 48; Taylor, 1976*: 34, pl. 6, fig. 59; Tester & Steidinger, 1979**: 30, fig. 74; Dodge, 1985***: 18 (fig. below, not above where D. tripos is illustrated); Hernandez-Becerril, 1988a**: 192, pl. 5, fig. 34, 35 (a gamete; as Dinophysis sp.); Fukuyo et al., 1990** ***: 36, fig. A-E; Delgado & Fortuno, 1991*: fig. 4E; Licea et al., 1995**: 19, pl. 6, fig. 4; Steidinger & Tangen, 1996*: 431, pl. 12; Hansen et al., 2001**: 28, pl. 2, fig. E; Faust & Gulledge, 2002* ** ***: 26, pl. 13, fig. 1-6; Larsen & Nguyen, 2004**: 65, pl. 1, fig. 1-5; Alonso-Rodriguez et al., 2008**: 133; Hernandez-Becerril et al., 2008** ***: 3, fig. 6, 7, 9, 10 (also as D. diegensis); Al-Kandari et al., 2009**: 151, pl. 3, fig. E-H (p. 300); Esqueda-Lara & Hernandez-Becerril, 2010** ***: 145, fig. 138a-c.

3b. Dinophysis caudata var. abbreviata Jorg., 1923 (Pl. 2, Fig. 5 and 6; Pl. 11, Fig. 1 and 2). Syn.: Dinophysis homunculus f. ventricosa Pavill., 1916: 56, fig. 15B; D. caudata f. acutiformis Kof. et Skogsb., 1928: 231.

Cells are irregularly ovoid, with rounded angles and a poorly separated hypothecal conical projection directed posteriorly-ventrally, which can bear 1 to 3 knob-like spinules. The dorsal contour is straight in the proximal part of the hypotheca. The cell is widest at the level of R3, tapering anteriorly. R1, R2 and R3 are almost equal in length. The LSL is wide but narrower than in var. pedunculatum. The RSL is wedge-shaped, terminating at R3 and being very narrow between R2 and R3. The distal margin of the LSL is broadly rounded. Lb 60-90 [micron]m (73.0 [+ o -] 5.9 [micron]m), Lt 70-97.5 [micron]m (81.6 [+ o -] 6.2 [micron]m), Db 27.5-47.5 [micron]m (40.0 [+ o -] 3.9 [micron]m), Dt 35-67.5 [micron]m (50.4 [+ o -] 5.8 [micron]m); n=31.

Taxonomic note. Although Kofoid & Skogsberg (1928: 227) believe that D. caudata f. acutiformis has <<a rather uncertain systematic status>>, I consider it synonymous to var. abbreviata.

Records in the State of Veracruz: Legaria-Moreno, 2003 (as D. caudata var. ventricosa Pavillard). Rather common in NPSAV, most frequent in July.

References: Rampi, 1940*: 24, fig. 42 (as D. caudata f. acutiformis Kof. et Skogsb.); Yamaji, 1966*: 70, pl. 32, fig. 15 (as D. homunculus f. ventricosa Pavillard); Steidinger et al., 1967*: pl. 2, fig. b (as D. caudata var. B); Pesantes- Santana, 1978*: 20, pl. 14, fig. 4-6.

4. Dinophysis schroederi Pavill., 1909 (Pl. 3, Fig. 1; Pl. 11, Fig. 3).

Cells are asymmetrically subovoid, elongated, about 1.8 times longer than they are wide, with narrowly rounded epitheca and the posterior part of the hypotheca without antapical processes. The theca is coarsely areolated. The cell is widest at the level of the mid-distance between R2 and R3. The epitheca is very short and small, slightly convex. The hypotheca is asymmetrical in relation to the longitudinal axis of the cell, with a narrowly rounded posterior part. Its dorsal margin is well rounded at the level beween R2 and R3 and slightly convex toward both ends, and its ventral margin is straight or almost straight between R1 and R3. The cingulum is slightly convex or flat. The cingular lists are relatively wide, directed laterally- anteriorly. LSL is long and broad. RSL is subtrapezoidal, terminating just behind the base of R2. Both sulcal lists can be faintly or coarsely reticulate. The distance between R2 and R3 is about 1.5 times the distance between R1 and R2. R3 is the thickest and the longest, curved backward at its distal part, directed laterally-posteriorly in general, about 1.8 times longer than R2, almost reaching the level of the antapex. Lb 67.5 [micron]m, Lt 70 [micron]m, Db 41.5 [micron]m, Dt 56.5 [micron]m; n=1.

A new record for the State of Veracruz. Extremely rare in NPSAV; the species was found only on 10 May 2005 at St. 2 (AVM).

References: Pavillard, 1909*: 284, fig. 5; 1916*: 58, pl. 3, fig. 5; Kofoid & Skogsberg, 1928*: 257, fig. 31(6); Schiller, 1928*: 73, fig. 33; 1933*: 133, fig. 125; Rampi, 1940*: 21, fig. 28; Yamaji, 1966*: 70, pl. 32, fig. 6; Balech, 1971a*: 53, fig. 47-53; Delgado & Fortuno, 1991*: fig. 4C.

5. Dinophysis cf. similis Kof. et Skogsb., 1928 (Pl. 3, Fig. 2; Pl. 11, Fig. 4).

Cells are of moderate size, suboval, markedly asymmetrical in relation to the longitudinal axis of the cell, convex dorsally and posteriorly and almost straight between the cingulum and R3 in lateral view, with strongly areolated theca. Epitheca is low, widely rounded. Hypotheca is very broadly rounded. LSL is long, terminating in about 3/4 the cell length, located closer to the antapex, with a rounded posterior margin and no list behind R3. Both R2 and R3 are curved anteriorly in their distal parts. The distance between R2 and R3 is about twice that between R1 and R2. RSL is rather small, with a rounded margin, ending in mid-distance between R2 and R3. Lb 60 [micron]m, Db 53.5 [micron]m, Dt 61 [micron]m; n=1.

Morphological note. In the original description of D. similis, Kofoid & Skogsberg (1928: 247) stated that R3 was "absent or rudimentary (very short)". Our specimen fits rather well the illustrations of two cells in lateral view by Balech (1988); however, our specimen differs by (1) the wider anterior part of the cell, (2) a more rounded RSL, (3) a noticeably areolated theca, (4) the presence of R3, and probably (4) by the absence of strong ribs supporting ACL.

A new record for the State of Veracruz. Extremely rare in NPSAV; the species was found only on 26 October 2006 at St. 3 (AVM).

References for Dinophysis similis. Kofoid et Skogsberg, 1928*: 247, fig. 31(1, 2); Balech, 1962*: 122, pl. 17, fig. 248-250 (as D. simplex n. sp.; non D. simplex Bohm, 1933: 15, fig. 1a, b); 1988*: 42, pl. 6, fig. 1-4.

6. Dinophysis ovum F. Schutt, 1895 (Pl. 3, Fig. 3; Pl. 11, Fig. 5).

Cells are asymmetrically ovoid or subovoid, with a narrowly rounded epitheca and a broadly rounded hypotheca, without antapical processes. The theca is coarsely areolated. The cell is widest at the level of R3. The epitheca is very short and small, slightly convex. The hypotheca is asymmetrical in relation to the longitudinal axis of the cell, with the antapex slightly shifted ventrally. The cingulum is slightly convex or flat. The cingular lists are relatively wide, directed laterally-anteriorly. LSL is moderately broad. RSL is subtriangular, terminating at the base of R2 or just behind it. Both sulcal lists can be faintly or coarsely reticulate. The distance between R2 and R3 is usually slighly longer, sometimes about 1.5 times the distance between R1 and R2. R3 is the thickest and the longest, straight or somewhat curved, directed laterally-posteriorly or laterally, slightly longer than R2. Lb 42.5-52.5 [micron]m (46.8 [+ o -] 2.8 [micron]m), Lt 47.5-52.5 gm (52.1 [+ o -] 3.1 [micron]m), Db 34-42 [micron]m (36.8 [+ o -] 2.1 [micron]m), Dt 41.5-52 [micron]m (45.8 [+ o -] 2.6 [micron]m); n=32.

Affinities. The species is very similar to the toxic D. fortil, however, in general, the cells are shorter, less asymmetrical in relation to the longitudinal axis of the cell, and the base of R3 is usually located further from the antapex, at the distance of 3/5-213 of the cell length, while in D. fortiiat about 2/3 (for comparison, see D. fortii in Tai & Skogsberg, 1934: 439, fig. 5A-D; Abe, 1967a: 54, fig. 13; Balech, 1988: 43, pl. 6, fig. 19; Hallegraeff & Lucas, 1988: fig. 29b; Fukuyo et al., 1990: 38, fig. A-F; Larsen & Moestrup, 1992: 6, fig. 4a-c).

Records in the State of Veracruz: Avendano-Sanchez & Sotomayor-Navarro, 1982; Zamudio-Resendiz, 1998. Rare in NPSAV (May, June, Aug.).

References: Schutt, 1895*: pl. 1, fig. 6; Paulsen, 1908*: 17, fig. 16 (after Schutt, 1895); Pavillard, 1916*: 58, pl. 3, fig. 3; Lebour, 1925*: 81, pl. 12, fig. 3; Schiller, 1928*: 73, fig. 33; 1933*: 116, fig. 109 (after Lebour, 1925); Martin, 1929*: 21, pl. 2, fig. 10; Rampi, 1940*: 20, fig. 33; Balech, 1962*: 125, pl. 16, fig. 205-213; Yamaji, 1966*: 69, pl. 32, fig. 1; Abe, 1967a*: 50, fig. 10a-p; Steidinger & Williams, 1970**: pl. 17, fig. 49; Pesantes-Santana, 1978*: 20, pl. 14, fig. 8; Dodge, 1982*: 53, fig. 3J; Licea et al., 1995*: 20, pl. 20, fig. 14; Hernandez-Becerril et al., 2008**: 6, fig. 20.

7. Dinophysis cf. exigua Kof. et Skogsb., 1928 (Pl. 3, Fig. 4; Pl. 11, Fig. 6).

Cells are small, subglobal, somewhat asymmetrical in relation to the longitudinal axis of the cell, slightly ventrally compressed along LSL in lateral view. Thecal ornamentation is not distinguishable. The epitheca is very small, widely rounded. The cingulum is relatively narrow, slightly concave dorsally. The hypotheca is very broadly rounded posteriorly. LSL is relatively short, terminating about 0.6 of the cell length, continuously widening from R1 through R3. R1, R2 and R3 are equally distanced, R2 being longer than R1 but shorter than R3. RSL is as long as LSL but narrower, terminating at the base of R3. Lb 30-40 [micron]m (35.0 [+ o -] 7.1 [micron]m), Db 27.5-35 [micron]m (31.3 [+ o -] 6.0 [micron]m), Dt 36.5-45 [micron]m (40.1 [+ o -] 6.0 [micron]m); n=2.

Morphological note. The species was originally described from the eastern tropical Pacific. The main difference between our cell and the cells described and illustrated by both Kofoid & Skogsberg (1928) and Balech (1967a) is that the former has the LSL ribs equally distanced, and the latter has the distance between R2 and R3 about twice that between R1 and R2. Furthermore, these authors did not observe RSL, and in our specimen it was distinguishable, although faint. Another difference is that R3 is directed laterally in our cell and laterally-posteriorly in the specimens pictured by the other authors.

A new record for the State of Veracruz. Rare in NPSAV; the species was found only on 26 October 2006 at St. 3 (AVM), 29 May and 7 October 2007 at St. 7 (CEP-II).

References for Dinophysis exigua: Kofoid & Skogsberg, 1928*: 239, fig. 30; Balech, 1967a*: 86, pl. 1, fig. 4-12.

III. Genus Heteroschisma Kof. et Skogsb. ex J. Schill.

Heteroschisma sp. (Pl. 3, Fig. 5; Pl. 11, Fig. 7).

Cell almost regularly oval, broadly rounded anteriorly and more narrowly rounded posteriorly, without any antapical processes. The theca is covered by numerous small poroids. Epitheca is rather long, about half the length of the hypotheca. Hypotheca is slightly compressed in the sulcal area. Cingulum is rather wide, about 1/7 of the cell length, slightly convex. Cingular lists are laterally directed. Sulcal lists are narrow. LSL is rather long, supported by a thin, straight R3, situated rather close to the antapex; R2 is undistinguishable. RSL seems to be short, subtriangular. Lb 37.5 [micron]m, Db 31.5 [micron]m, Dt 35 [micron]m; n=1.

Morphological note. Our cell is similar to that illustrated by Balech (1988: 38, pl. 5, fig. 1, 2), who failed to identify it to the species level, although he was almost sure that it was yet undescribed. Unlike Balech's specimen, our cell has the posterior margin of LSL not rounded and has a longer RSL.

A new record of a Heteroschisma species for the State of Veracruz. Extremely rare in NPSAV. The only cell was found on 26 October 2006 at St. 3 (AVM).

IV. Genus Pseudophalacroma Jorg.

Pseudophalacroma nasutum (F. Stein) Jorg., 1923 (Pl. 3, Fig. 6-9; Pl. 11, Fig. 8). Bas.: Phalacroma nasutum F. Stein, 1883: pl. 18, fig. 1-6. Syn.: Prodinophysis nasuta (F. Stein) A. R. Loebl., 1965: 16; Dinophysis nasuta (F. Stein) Parke et Dixon, 1968: 797.

Cell almost regularly oval, broadly rounded anteriorly and more narrowly rounded posteriorly, without any antapical processes. Theca is coarsely areolated. Epitheca is rather high, about 0.2 of the hypotheca. A large pore is located near the suture between two epithecal plates, on left side, at about 0.25 of the length of the left epithecal plate measured along the suture. Cingulum is rather narrow, deeply excavated, with one row of pores. Cingular lists are laterally directed. LSL is short (about half the length of the hypotheca) and narrow, ear-shaped, supported by a curved R3, thickened at the base. RSL is barely visible in lateral view, trapezoidal, about 0.6 of the LSL length. Lb 50 [micron]m, Db 45 [micron]m, Dt 49 [micron]m, W 32 [micron]m; n=1.

Taxonomical note. A specimen from Veracruz shares the most of common features with Pseudophalacroma nasutum in Tai & Skogsberg (1934): (1) one row of pores in the middle of the cingulum; (2) the apical pore rather far from the cingulum; (3) short, fairly narrow LSL rounded posteriorly, without marked ribs R1 and R2; (4) shape and length of RSL; and (5) coarsely areolated theca. Stein (1883) illustrated his specimen with more than one row of cingular pores and a widely rounded hypotheca. Tai & Skogsberg (1934) gave a detailed description of both the genus Pseudophalacroma and the species P nasutum, and our specimen corresponds rather well to the cells pictured in their work. However, our cell has the maximum depth just below the cingulum, while in Tai & Skogsberg it is located in the middle part of the hypotheca. Abe (1967b: 104) considers that the species illustrated under the name of Pseudophalacroma nasutum cannot be assigned to the genus Pseudophalacroma and that most likely it is Metaphalacroma. The specimen from Veracruz is also similar to the type species Heteroschisma inaequale Kof. et Skogsb.; however, I cannot assign it either to the genus Heteroschisma Kof. et Skogsb. or to the genus Metaphalacroma Tai et Skogsb. because it has only one row of cingular pores (in both aforementioned genera there are two rows, judging from H. inaequale in Kofoid & Skogsberg (1928: pl. 1, fig. 7, 8) and Tai & Skogsberg (1934: 457, fig. 11).

A new record for the Gulf of Mexico, for which it has not yet been reported (see Steidinger et al., 2009: 149-152). The only cell was found on 19 September 2007 at St. 2 (CEP-II).

References: Tai & Skogsberg, 1934*: 469, fig. 13A-K.

V. Genus Histioneis Stein

Key for identification of Histioneis species

1a Cells longer than they are wide, hypotheca is symmetrical
in relation to the longi tudinal axis of the cell

1b Cells wider than they are long, kidney- or bean-shaped
hypotheca is asymmetrical in relation to the longitudinal
axis of the cell

2a Epitheca is located in the middle in lateral
view (1) Histioneis paraformis

2b Epitheca is displaced to the ventral side of the cell

3a Hypotheca with large poroids, ACL is relatively
narrow (about 1/3 of the cell
body length) (2) Histioneis crateriformis

3b Hypotheca with small poroids, ACL is relatively
wide (about 1/2 of the cell body
length) (3) Histioneis karstenii

4a Cells about twice as wide as they are long, with
a strongly curved and long R2 fused with R3 forming
a loop (4) Histioneis longicollis

4b Cells slightly wider than they are long, with separated R2 and R3
(5) Histioneis isseli


1. Histioneisparaformis (Kof. et Skogsb.) Balech, 1971 (Pl. 4, Fig. 1; Pl. 11, Fig. 9). Bas.: Parahistioneisparaformis Kof. et Skogsb., 1928: 598, fig. 93(4), pl. 19, fig. 3, 6. Syn.: Histioneis para G. Murray et Whitting, 1899, partim: 333, fig. 4c (non fig. 4a, b); Parahistioneis acuta Bohm, 1931 in J. Schill., 1933: 216, fig. 206; Histioneis acuta in Balech, 1971 (Publ. Serv. Hidrogr. Naval B. Aires H 654): pl. 3, fig. 50.

Cell bodies are suboval, symmetrical in relation to their longitudinal and latitudinal axes, with narrowly rounded antapex. The epitheca is small, centrally positioned. ACL is relatively wide, funnel-shaped. PCL is moderately wide, about 0.5 of the cell body depth, supported with vertical divergent ribs directed anteriorly-laterally. LSL is moderately developed, finely reticulate. R3 is about 1.5 times shorter than the cell body length, emerging ventrally-posteriorly. Lb 27-32.5 [micron]m (29.3 [+ o -] 2.5 pm), Lt 55-67.5 [micron]m (62.5 [+ o -] 6.1 [micron]m), Db 24-30 [micron]m (26.9 [+ o -] 2.8 [micron]m), Dt 29-42.5 [micron]m (37.3 [+ o -] 5.9 [micron]m); n=4.

Affinities. Our specimen corresponds more to Histioneis acuta in Balech (1971b: pl. 3, fig. 50), which is considered here, following Balech, a synonym to H. paraformis. A new combination, Histioneis acuta, appearing in Balech, 1971b (p. 15: as H. acuta; in figure legend to pl. 3, fig. 50 as H. acuta?) is invalid because no reference to the basionym was given. Histioneis paraformis is morphologically similar to H. para (see Murray & Whitting, 1899*: pl. 32, fig. 4; Schiller, 1933*: 215, fig. 205a, b; Balech, 1962*: 137, pl. 17, fig. 254; 1988*: 65, pl. 15, fig. 4; Taylor, 1976* ***: 53, pl. 9, fig. 87, 88, pl. 41, fig. 490; Hernandez-Becerril, 1988a**: 193, pl. 5, fig. 31, 32; Hernandez-Becerril et al., 2008**: 7, fig. 65; Esqueda- Lara & Hernandez-Becerril, 2010**: 159, fig. 150a-c). However, the latter is different in having (1) a narrower rounded posterior end of the cell body, (2) a posterior rib (R3) emerging from the antapex, (3) the absence of ribs other than R3, and (4) a strongly reticulated LSL.

A new record for the State of Veracruz. Extremely rare in NPSAV; the species was found only on 26 October 2005 at St. 3 (AVM).

References: Murray & Whitting, 1899*: 333, pl. 32, fig. 4c; Yamaji, 1966*: 71, pl. 32, fig. 19; Balech, 1971b*: 14, pl. 3, fig. 47-49.

2. Histioneis crateriformis F. Stein, 1883 (Pl. 4, Fig. 2; Pl. 11, Fig. 10). Syn.: Parahistioneis crateriformisF. Stein, 1883: pl. 22, fig. 5, 6; P. acutiformisRampi, 1947: 5, fig. 4.

Cell bodies are kidney-shaped, with the hypotheca symmetrical or slightly asymmetrical in relation to its longitudinal axis. The epitheca is minute. The dorsal edge of the cingulum is markedly concave and it is about twice as large as the ventral edge. ACL is about 0.36 of the cell body length, widely tubular, funnelshaped. PCL is short, about 0.33-0.50 of the cell-body length, slightly narrower than the maximum cell body depth, supported by somewhat curved vertical ribs. LSL is moderately developed, reticulate mostly in its anterior part (between R1 and R2). R3 is about 0.38-0.46 of the cell body length, emerging ventrally-posteriorly. Lb 30-37.5 pm (34.7 [+ o -] 4.1 [micron]m), Lt 50-65 [micron]m (58.7 [+ o -] 7.8 [micron]m), Db 32.5-35 [micron]m (33.8 [+ o -] 1.3 [micron]m), Dt 37.5-42 [micron]m (39.8 [+ o -] 2.3 [micron]m); n=3.

Morphological note. All three examined cells demonstrated variation in the number of morphological characteristics, so that they can be ascribed either to H. crateriformis or H. reticulata Kof. et Skogsb. In the original illustration of H. crateriformis by Stein (1883), the ACL is as long as about 0.60 of the cell-body length, which is the main distinguishing feature between Stein's specimens and our cells. On the other hand, in their original drawing Kofoid et Skogsberg (1928: pl. 19, fig. 7, 10) describe H. reticulata with a relatively robust cell body, a shorter R3 (0.25 of the cell-body length) and finely reticulated LSL and PCL, which principally distinguishes this species from the the cells from Veracruz (a poorly visible reticulation was defined in three cells, but it did not occupy the whole LSL). Although I follow Balech's (1971b) opinion about the synonymy of H. acutiformis to H. crateriformis, one should consider that R3 in the former is much longer, and its position is different (more ventral), although the species was described on the basis of only one cell.

Records in the State of Veracruz: Zamudio-Resendiz, 1998. Extremely rare in NPSAV; the species was found only on 26 October 2005 at St. 3 (AVM).

References: Stein, 1883*: 25, pl. 22, fig. 5, 6; Balech, 1971b*: 15, pl. 3, fig. 40-46; 1988*: 68, pl. 15, fig. 8; Hernandez-Becerril et al., 2008**: 6, fig. 63; Esqueda-Lara & Hernandez-Becerril, 2010**: 157, fig. 151a, b.

3. Histioneis karstenii Kof. et J. R. Michener, 1911 (Pl. 4, Fig. 3; Pl. 11, Fig. 11). Syn.: Parahistioneis karstenii (Kof. et J. R. Michener) Kof. et Skogsb., 1928: 603, fig. 93(2), pl. 19, fig. 2.

Cell bodies are suboval, slightly asymmetrical in relation to their longitudinal and latitudinal axes, with a larger dorsal half. The epitheca is minute, positioned slightly closer to the ventral side. ACL is about 0.5 of the cell body length, widely tubular, funnel-shaped. PCL is short, less than 0.5 of the cell body depth, and as wide as the cell body depth, supported by somewhat curved vertical and horizontal ribs; the vertical ribs are parallel to each other in general. LSL is moderately developed, somewhat reticulate. R3 is about half of the cell body length, emerging ventrally-posteriorly. Lb 25 [micron]m, Lt 50 [micron]m, Db 25 [micron]m, Dt 31.5 [micron]m; n=1.

Morphological note. Our specimen corresponds rather well with those in Kofoid & Skogsberg (1928) and Rampi (1939, 1947). Unlike those authors, who pictured the cells with a list behind R3 clearly extended to the dorsal part of cell, the cell from Veracruz has a narrower list that does not reach the antapex. It is also somewhat similar to the cell of H. oxypteris J. Schill. illustrated by Schiller (1928: 82, pl. 3, fig. 6; non fig. 7, lapsus clavia); however, the latter has no R2 and lacks a list behind R3. On the contrary, our specimen looks very similar to the picture of the cell of H. oxypteris in Balech (1971b: 17, pl. 3, fig. 35-36).

A new record for the State of Veracruz. Extremely rare in NPSAV; the species was found only on 26 October 2005 at St. 3 (AVM).

References: Kofoid & Skogsberg, 1928*: 603, fig. 93(2), pl. 19, fig. 2; Schiller, 1933*: 217, fig. 207 (after Kofoid & Skogsberg, 1928); Rampi, 1939*: 460, fig. 4; 1947*: 5, fig. 2.

4. Histioneis longicollis Kof., 1907 (Pl. 4, Fig. 4; Pl. 11, Fig. 12).

Cell bodies are bean-shaped or kidney-shaped, concave anteriorly and convex posteriorly, asymmetrical in relation to their longitudinal and latitudinal axes, with a larger dorsal half. The epitheca is minute. The dorsal edge of the cingulum is slightly or moderately concave, and it is about 2-3 times larger than the ventral edge, which is almost straight or somewhat convex. ACL is about 1.5 larger than the cell body length, narrowly tubular, funnel-shaped, with the dorsal margin more extended than the ventral one. PCL is large, slightly narrower than the cell body depth, and it is as long as the cell body or even longer, supported by straight or sigmoid vertical (including 2 dorsal ribs) and horizontal ribs, forming a sort of subquadrangular chamber; horizontal ribs support PCL near its anterior margin. LSL is well developed, somewhat reticulate, posteriorly extending far beyond the cell body (up to 2.0-2.8 times its length), supported ventrally-posteriorly, along the inner side of LSL, mainly by 2 (or 3?) ribs that fuse, forming a suboval frame (window), continuing as the only rib directed backward. Lb 19-24.5 [micron]m (20.8 [+ o -] 1.6 pm), Lt 65-81 [micron]m (69.5 [+ o -] 4.9 [micron]m), Db 24-32.5 [micron]m (30.0 [+ o -] 2.5 [micron]m), Dt 35-41 [micron]m (37.7 [+ o -] 1.6 [micron]m); n=11.

Affinities. Our cells show a morphology intermediate between that of H. hyalina Kof. et J. R. Michener (Kofoid & Skogsberg, 1928*: 679, fig. 95(5), pl. 20, fig. 4) and H. longicollis (see Kofoid, 1907*: 204, pl. 16, fig. 100; Kofoid & Skogsberg, 1928*: 677, fig. 95(7), pl. 20, fig. 5, pl. 21, fig. 5). I ascribe it to H. longicollis due to the longer cells and less anterior-posterior compression of the cell body. Furthermore, it is similar to H. joergensenii J. Schill.; however, the latter has a slightly lower PCL, a markedly longer LSL, and a less anteriorily- posteriorly compressed cell body (Schiller, 1928: 83, fig. 42). Additionally, some similarities occur between H. longicollis and H. cymbalaria F. Stein (= H. depressa J. Schill.), but the latter has a much more symmetrical and more anteriorily-posteriorly compressed, shoe-like cell body (see Stein, 1883*: 25, pl. 22, fig. 7-10; Schiller, 1928*: 84, fig. 43; 1933*: 237, 240, fig. 230, 236; Rampi, 1941*: 119, fig. 1; 1947*: 12, fig. 14; Wood, 1963*: 6, fig. 13; 1968*: 77, fig. 212; Balech, 1971a*: 81, fig. 18-19; 1971b*: 21, pl. 1, fig. 14-17, pl. 2, fig. 18; Taylor, 1976*: 44, pl. 10, fig. 94; Esqueda-Lara & Hernandez-Becerril, 2010**: 158, fig. 149a-c). Even more species have a loop formed by the fission rib (R2) and the posterior rib (R3): H. gubernans F. Schutt, H. pavillardii Rampi, H. detonii Rampi (Rampi, 1939: 460, 461; 1940: 28, fig. 48; 1947: 11, 13), H. pacifica Kof. et Skogsb. (Kofoid & Skogsberg, 1928: 681, fig. 95(12), pl. 20, fig. 8; Balech, 1971b: 17, pl. 2, fig. 22, 25, 27, 28), H mitchellana G. Murray et Whitting (Murray & Whitting, 1899: 335, pl. 33, fig. 3), and H. voukii J. Schill. (Schiller, 1928: 82, fig. 41). The problem of as yet unknown infraspecific variation significantly hinders the correct identification at the species level; for example, many Histioneis (more than 50% of known species) and Dinophysis species were described based on a single specimen (Balech, 1971b: 14; Hallegraeff & Lucas, 1988: 25).

A new record for the State of Veracruz. Extremely rare in NPSAV; the species was found only on 26 October 2005 at St. 3 (AVM).

References: Kofoid et Skogsberg, 1928*: 679, fig. 95(5), pl. 20, fig. 4; Schiller, 1928*: 81, pl. 3, fig. 6; 1933*: 238, fig. 231a; Rampi, 1940*: 29, fig. 47; Balech, 1971b*: 19, pl. 2, fig. 26, 29, 31.

5. Histioneis isseli Forti, 1932 (Pl. 4, Fig. 5; Pl. 7, Fig. 4; Pl. 11, Fig. 13).

Cell bodies are kidney- or bean-shaped, asymmetrical in relation to their longitudinal and latitudinal axes, with a larger dorsal half. The epitheca is minute. ACL is about as long as the cell body length, widely tubular, funnel-shaped. PCL is moderately developed, as wide as the cell body depth, and it is as long as the cell body, supported by slightly curved vertical and horizontal ribs. LSL is moderately developed, somewhat reticulate, markedly pitted before R2. R2 is small, curved, directed posteriorlylaterally. R3 is slightly longer than the cell body, almost straight or somewhat curved, emerging from the antapical end of the body. Lb 25-27.5 [micron]m (26.7 [+ o -] 1.4 [micron]m), Lt 72.5-80 pm (77.5 [+ o -] 4.3 [micron]m), Db 30-37.5 [micron]m (34.2 [+ o -] 3.8 [micron]m), Dt 35-45 [micron]m (40.0 [+ o -] 5.0 [micron]m); n=3.

Affinities. Our specimens have some features in common with H. subcarinata Rampi (Rampi, 1940*: 30, fig. 46 (as H. carinata Kof); 1947*: 13, fig. 8; Balech, 1971b*: 20, pl. 2, fig. 19, 20). Unlike the latter, they have (1) less curved R3, (2) R2 directed posteriorly-laterally, and (3) LSL of a different shape, especially in its posterior part. Histioneis isseli is also morphologically similar to H carinata Kof. (Kofoid, 1907: 203, pl. 16, fig. 98); however, the latter has (1) a larger and wider, more anteriorly-posteriorly compressed cell body, dorsally diminishing in size, (2) a much more curved R3, and (3) a LSL of a different shape, especially in its posterior part.

A new record for the Gulf of Mexico. Extremely rare in NPSAV; the species was found only on 26 October 2005 at St. 3 (AVM).

References: Forti, 1932*: 539, fig. 1; Hernandez-Becerril, 1988a**: 192, pl. 2, fig. 8; 1988b**: pl. 1, fig. 8.

VI. Genus Ornithocercus F. Stein

Key for identification of Ornithocercus species

1a Left sulcal list (LSL) reaches the antapex

1b LSL extends onto the dorsal side of the cell

2a Posterior-ventral part of LSL (= posterior sail)
slightly convex and subequal to
the cell body length (1) Ornithocercus cristatus

2b Posterior-ventral part of LSL concave and wider
than the cell body length
(2) Ornithocercus heteroporus

3a Posterior-ventral part of LSL is not divided into lobes
(3) Ornithocercus quadratus

3b Posterior-ventral part of LSL is divided into lobes

4a Cell body relatively small (40-47 [micron]m in length),
posterior-ventral part of LSL
three-lobed (4) Ornithocercus magnificus

4b Cell body is relatively large (50-63 [micron]m in length,
sometimes less), posterior ventral part of LSL consisting
of more than three lobes or unclearly lobed

5a Posterior margin of LSL supported by 5 main ribs that
alternate in length (longer and shorter ones) (5) Ornithocercus thumii

5b Posterior margin of LSL supported by 3-5 main ribs
of about equal length

6a Posterior margin of LSL supported by 3 main ribs, being
slightly three-lobed (6) Ornithocercus skogsbergii

6b Posterior margin of LSL supported by 4 main ribs,
being slightly four-lobed (7) Ornithocercus steinii


1. Ornithocercus cristatus Matzen., 1933 (Pl. 4, Fig. 6; Pl. 12, Fig. 1).

Cell body is small, suboval, elongated, slightly asymmetrical. Cingulum is not excavated. LSL extends to the antapex, with a more or less direct ventral margin and a sigmoid posterior margin, forming almost a right angle; behind the sulcus the LSL is supported with one thick and a number of thin ribs. Lb 30-37 [micron]m (33.2 [+ o -] 3.5 pm), Lt 65-77 [micron]m (71.3 [+ o -] 6.0 [micron]m), Db 27.5-32.5 [micron]m (30 [+ o -] 2.5 [micron]m), Dt 32.5-54 [micron]m (45.5 [+ o -] 11.4 [micron]m); n=3.

Morphological note. All three cells were found in the same sample together with O. heteroporus, so their belonging to the latter should not be excluded (in this case, it may be a young cell, sometimes called schizont; see Norris, 1969). However, the examined cells are in accordance with the original line drawing by Matzenauer (1933) by (1) their elongated, almost symmetrical cell body (although our cells have a narrower rounded antapex), (2) the posterior margin of LSL parallel to the sulcus, (3) the absence of 2 or 3 thick main radial ribs, and (4) the cingulum not excavated. In Matzenauer's figure, LSL has a continuously convex margin.

A new record for the State of Veracruz. Extremely rare in NPSAV; the species was found only on 26 October 2005 at St. 3 (AVM).

References: Matzenauer, 1933*: 447, fig. 11; Balech, 1967a*: 93, pl. 2, fig. 3846; Hernandez-Becerril et al., 2008**: 9, fig. 33.

2. Ornithocercus heteroporus Kof., 1907 (Pl. 4, Fig. 7 and 8; Pl. 12, Fig. 2). Syn.: Ornithocercus biclavatus Wood, 1954: 211, fig. 66.

Cell bodies are small, oval, slightly elongated obliquely along the longitudinal axis (from its posterior dorsal end to anterior ventral end). Cingulum is slightly or not excavated. LSL extends to the antapex, with more or less direct or slightly convex ventral margin and concave posterior-ventral margin; behind the sulcus it is supported by two thick main ribs as long as the cell depth, divergent in their proximal parts and parallel or slightly convergent in their distal parts, and 4-5 additional thinner ribs. Lb 32.5-35 [micron]m (33.8 [+ o -] 1.1 [micron]m), Lt 65-80 [micron]m (72.9 [+ o -] 6.2 [micron]m), Db 30-36.5 qm (32.6 [+ o -] 3.6 [micron]m), Dt 45-55 [micron]m (49.7 [+ o -] 3.4 [micron]m); n=5.

Records in the State of Veracruz: Okolodkov et al., 2011. Extremely rare in NPSAV; the species was found only on 26 October 2005 at St. 3 (AVM).

References: Kofoid, 1907*: 206, pl. 12, fig. 70; Kofoid & Skogsberg, 1928*: 517, fig. 75, 76, pl. 18, fig. 1, 3; Schiller, 1933*: 195, fig. 187a-d (after Kofoid & Skogsberg, 1928); Rampi, 1940*: 25, fig. 53; Yamaji, 1966*: 72, pl. 33, fig. 9; Abe, 1967b*: 81, fig. 28a, b; Taylor, 1976*: 48, pl. 8, fig. 83; Balech, 1988*: 59, pl. 14, fig. 4; Delgado & Fortuno, 1991* ***: fig. 4M, pl. 32, fig. c; Licea et al., 1995*: 23, pl. 21, fig. 11; Steidinger & Tangen, 1996*: 436, pl. 13; Hernandez-Rosas et al., 2007**: 266, fig. 3c, 4(b1-b5); Hernandez-Becerril et al., 2008**: 9, fig. 32; Esqueda- Lara & Hernandez-Becerril, 2010**: 162, fig. 155a-c.

3. Ornithocercus quadratus F. Schutt, 1900 (Pl. 4, Fig. 9; Pl. 12, Fig. 3). Syn.: Histioneis quadrats Lemmerm., 1901: 376; Ornithocercus similis Jorg., 1923: 37, fig. 51.

Cells bodies are large, suboval, slightly deeper than long, with the epitheca markedly displaced to the ventral side. Cingulum is dorsally excavated and distinctly wider than ventrally. LSL extends to one-third (posterior-dorsal) of the dorsal side of the cell, forming a more or less rectangular outline behind the cell body. Behind the sulcus it is supported by 8-9 main ribs directed posteriorly- laterally or posteriorly. Both ventral and dorsal margins of LSL are slightly convex, and the posterior margin is undulating, almost straight. Three posterior ribs (B, C and D; for rib designation, see Schutt, 1900: 254, Fig. 1-10) are of equal or subequal length, located closer to each other. RSL is rather broad, extending almost to the antapex, terminating near the group of three posterior ribs. Small ribs originating from the surrounding rib are common along the margin of LSL from the sulcus to the dorsal side. Some cells with exosymbiotic cyanobacteria were observed. Lb 55-66.5 [micron]m (59.5 [+ o -] 3.2 [micron]m), Lt 122-142.5 [micron]m (130.5 [+ o -] 11.8 [micron]m), Db 63-72.5 [micron]m (70.3 [+ o -] 5.0 [micron]m), Dt 91-117.5 [micron]m (107.6 [+ o -] 13.2 [micron]m); n=10.

Morphological note. Our cells correspond to the observation by Abe (1967b: 89) who described rib C as "lying somewhat slantwise as its basal end is deflected toward the right" and who was the first to illustrate this peculiarity, although it is not thinner than the neighboring ribs B and D.

Records in the State of Veracruz: Zamudio-Resendiz, 1998; Aquino-Cruz, 2002* ** (misidentification; referred to as O. steinii); Okolodkov et al., 2011. Very rare in NPSAV; the species was observed only on 13 October 2006 at St. 9 (CEP-I) and on 26 October 2006 at St. 3 (AVM).

References: Schutt, 1900*: 5, fig. 1-4, 12, 13; Kofoid & Skogsberg, 1928*: 561, fig. 85(5), 86-88, pl. 17, fig. 2, 8; Schiller, 1933*: 204, fig. 194a-f, 195a-d (after Kofoid & Skogsberg, 1928); Rampi, 1939: 459, fig. 11; 1940*: 25, fig. 55; Abe, 1967b*: 89, fig. 33a, b; Norris, 1969*: fig. 20; Taylor, 1976* ***: 50, pl. 8, fig. 77-82, pl. 42, fig. 499-501; Pesantes-Santana, 1978*: 25, pl. 16, fig. 11; Dodge, 1985***: 29; Balech, 1988*: 60, pl. 14, fig. 10; Steidinger & Tangen, 1996*: 436, pl. 13; Hernandez-Rosas et al., 2007** ***: 267, fig. 2a-f, 3f (mistakenly, in the legend to fig. 3 it is referred to fig. 3e), 4(d1-d5), 11d; Esqueda-Lara & HernandezBecerril, 2010**: 165, fig. 158a-c (var. assimilis (Jorg.) Taylor), 166, fig. 159 (var. simplex Kof. et Skogsb.).

4. Ornithocercus magnificus F. Stein, 1883 (Pl. 5, Fig. 1-3; Pl. 8, Fig. 1 and 2; Pl. 12, Fig. 4).

Cell bodies are relatively small, subcircular in lateral view, slightly asymmetrical in relation to the longitudinal axis, directed from the posterior dorsal end to anterior ventral end. Cingulum is slightly excavated. LSL extends to one- third (posterior-dorsal) of the dorsal side of the cell. Behind the sulcus it is supported by 5 main ribs directed posteriorly, of which 3 ribs (B, C and D) positioned antapically are located closer to each other, and the central rib of these three is situated out of the plane of the other two (which is clearly seen in ventral or dorsal view; Pl. 7, Fig. 5 and 6). The posterior margin of LSL is clearly three-lobed, forming two concavities asymmetrically located on both sides of the group of three posterior main ribs, the central rib being the longest. Sometimes the main ribs form anastomoses between them; the main ribs also do the same where they connect with the posterior marginal rib, forming nodes. RSL is narrow, terminating behind the main rib located closer to the sulcus. Some cells with exosymbiotic cyanobacteria were observed. Lb 40- 47 pm (43.4 [+ o -] 2.1 [micron]m), Lt 92.5-115 [micron]m (105.7 [+ o -] 7.1 [micron]m), Db 41-46.5 [micron]m (43.3 [+ o - ] 1.4 [micron]m), Dt 75-93 [micron]m (83.4 [+ o -] 5.0 [micron]m); n=29.

Records in the State of Veracruz: Avendano-Sanchez & Sotomayor-Navarro, 1982; Zamudio-Resendiz, 1998; Okolodkov et al., 2011. The most common species in the genus Ornithocercus in the study area (Jan., Aug., Oct. Nov., Dec.).

References: Stein, 1883*, pro parte: pl. 23, fig. 1, 2 (non fig. 3-6); Schutt, 1895*: pl. 5, fig. 21; 1899*: 690, fig. 12; 1900*: 262, fig. 8-10; Kofoid & Skogsberg, 1928*: 529, fig. 79, 80, pl. 16, fig. 3; Schiller, 1933*: 198, fig. 190a, b (after Kofoid & Skogsberg, 1928); Rampi, 1940*: 25, fig. 54; Silva, 1955*: 131, pl. 3, fig. 5; Yamaji, 1966*: 72, pl. 33, fig. 5; Abe, 1967b*: 88, fig. 32a-d; Norris, 1969*: 178, fig. 2-15, 17(?); Steidinger & Williams, 1970**: pl. 25, fig. 79; Taylor, 1976* ***: 49, pl. 7, fig. 67-69, pl. 42, fig. 505a, b; Pesantes-Santana, 1978*: 25, pl. 16, fig. 12; Tester & Steidinger, 1979**: 30, fig. 75; Dodge, 1985***: 28; Balech, 1988*: 61, pl. 14, fig. 7, 8; Hernandez-Becerril, 1988a**: 193, pl. 2, fig. 9, 10; Delgado & Fortuno, 1991* ***: 5, fig. 4L, pl. 32, fig. d; Licea et al., 1995* ***: 23, pl. 8, fig. 3, pl. 21, fig. 12; Steidinger & Tangen, 1996*: 436, pl. 13; Hernandez-Rosas et al., 2007** ***: 266, fig. 3d, 4(c1-c5), 11a, b; Alonso-Rodriguez et al., 2008**: 138; Hernandez-Becerril et al., 2008**: 9, fig. 28; Al-Kandari et al., 2009**: 153, pl. 5, fig. C (p. 302); Esqueda-Lara & Hernandez-Becerril, 2010**: 163, fig. 156a-c.

5. Ornithocercus thumii (Schmidt) Kof. et Skogsb., 1928 (Pl. 5, Fig. 4; Pl. 12, Fig. 5). Bas.: Parelion thumii Schmidt, 1888: pl. 144(59-61).

Cells bodies are large, suboval, slightly deeper than long, with the epitheca markedly displaced to the ventral side. The cingulum is dorsally excavated and distinctly wider than ventrally. LSL extends to one-half of the dorsal side of the cell. Six main ribs behind the sulcus are spaced almost equally. The posterior margin of LSL is supported by 5 main ribs and forms two concavities between them; in the center of each of them the shorter ribs B and D are located. RSL is narrow, expanding continuously posteriorly, terminating about half-way from the sulcus to the antapex. Some cells with exosymbiotic cyanobacteria were observed. Lb 50-60 [micron]m (56.2 [+ o -] 2.8 pm), Lt 112.5-140 [micron]m (127.0 [+ o -] 9.5 [micron]m), Db 60-67.5 [micron]m (62.5 [+ o -] 1.9 [micron]m), Dt 92.5- 120 pm (101.9 [+ o -] 7.7 [micron]m); n=24.

Records in the State of Veracruz: Zamudio-Resendiz, 1998; Okolodkov et al., 2011. Rare in NPSAV; the species was found only on 26 October 2005 at St. 3 (AVM).

References: Stein, 1883*: pl. 23, fig. 4, 5 (misidentification, reported as O. magnificus, non fig. 1-3, 6); Schutt, 1900*: fig. 7 (misidentification, reported as O. Steinii); Kofoid & Skogsberg, 1928*: 540 (mistakenly spelled as O. thurni), fig. 81, 82, pl. 18(4-6); Schiller, 1933*: 201 (mistakenly spelled as O. Thurnii), fig. 191a-h (after Murray & Whitting, 1899; Kofoid & Skogsberg, 1928); Yamaji, 1966*: 72, pl. 33, fig. 6 (misidentification, reported as O. steinii); Abe, 1967b*: 90, fig. 34a-i (mistakenly spelled as O. thurnii); Wood, 1968*: 87, fig. 244 (misidentification; reported as O. steini), fig. 245; Norris, 1969*: fig. 23 (mistakenly spelled as O. thurni); Steidinger & Williams, 1970**: pl. 25, fig. 81; Taylor, 1976*: 53, pl. 7, fig. 71, 72, 74; Steidinger & Tangen, 1996*: 437, pl. 13; Hernandez-Rosas et al., 2007** ***: 269 (mistakenly, O. magnificus is indicated as a synonym to O. thumii), fig. 3i, 4(f1-f5), 10a, 11f; Hernandez-Becerril et al., 2008** ***: fig. 36, 37 (misidentification; referred to as O. steinii); Esqueda-Lara & Hernandez-Becerril, 2010**: 168, fig. 161a-c (misidentification; referred to as O. steinii), 169, fig. 162.

6. Ornithocercus skogsbergii T. H. Abe, 1967 (Pl. 5, Fig. 5; Pl. 12, Fig. 6).

Cells bodies are relatively small, suboval, slightly deeper than long, with the epitheca markedly displaced to the ventral side. The cingulum is dorsally excavated and distinctly wider than ventrally. LSL extends to one-half of the dorsal side of the cell. Five thick main ribs behind the sulcus are spaced almost equally. The posterior margin of LSL is supported by 3 main ribs and forms two concavities between them. RSL is narrow, expanding continuously posteriorly, terminating rather far from the antapex. One cell with exosymbiotic Synechococcus was observed. Lb 47 [micron]m, Lt 100 [micron]m, Db 50 [micron]m, Dt 80 [micron]m; n=1.

A new record for the State of Veracruz. Extremely rare in NPSAV; the species was found only on 10 May 2005 at St. 4 (AVM).

References: Abe, 1967b*: 85, fig. 31a-k; Taylor, 1976*: 51, pl. 7, fig. 70.

7. Ornithocercus steinii F. Schutt, 1900 (Pl. 5, Fig. 6; Pl. 8, Fig. 3 and 4; Pl. 12, Fig. 7). Syn.: Ornithocercus serratus Kof., 1907 (Bull. Mus. Compar. Zool. Harvard Coll. 50, 6): 206, pl. 15, fig. 93.

Cells bodies are large, suboval, slightly deeper than long, with the epitheca markedly displaced to the ventral side. The cingulum is dorsally excavated and distinctly wider than ventrally. LSL extends to nearly one-half of the dorsal side of the cell. Six main ribs behind the sulcus are spaced almost equally. The posterior margin of LSL is supported by 4 main ribs and forms three concavities between them. RSL is narrow, expanding continuously posteriorly, terminating about half-way from the sulcus to the antapex. Some cells with exosymbiotic cyanobacteria were observed. Lb 52-62.5 [micron]m (58.8 [+ o -] 2.4 [micron]m), Lt 134-162.5 [micron]m (141.3 [+ o -] 10.2 [micron]m), Db 62.5-72.5 [micron]m (68.0 [+ o -] 2.6 [micron]m), Dt 90-125 [micron]m (113.6 [+ o -] 6.7 [micron]m); n=35.

Records in the State of Veracruz: Avendano-Sanchez & Sotomayor-Navarro, 1982 (as O. serratus); Okolodkov et al., 2011. Rare in NPSAV (March, May, Oct.).

References: Schutt, 1900*, pro parte: fig. 5, 6 (non fig. 7); Silva, 1955*: 131, pl. 3, fig. 6 (?); Yamaji, 1966*: 72, pl. 33, fig. 7 (as O. serratuS); Halim, 1967**: 731, pl. 5, fig. 65; Norris, 1969*: fig. 22; Steidinger & Williams, 1970**: pl. 25, fig. 80; Taylor, 1976*: 52, pl. 7, fig. 72, 73; Pesantes-Santana, 1978*: 25, pl. 17, fig. 1-3 (mistakenly spelled as O. Steinu); Balech, 1988*: 61, pl. 15, fig. 1; Delgado & Fortuno, 1991*: 5, fig. 4O; Licea et al., 1995***: 24, pl. 21, fig. 13; Steidinger & Tangen, 1996*: 437, pl. 13; Hernandez-Rosas et al., 2007** ***: 267, fig. 3h (mistakenly, in the legend to fig. 3 it is referred to fig. 3f), 4(e1-e5), 10b, 11e.
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Title Annotation:p. 9-43; articulo en ingles
Author:Okolodkov, Yuri B.
Publication:Acta Botanica Mexicana
Date:Jan 1, 2014
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