Fishes of the Helcogramma steinitzi species group (Blennioidei: Tripterygiidae) from the Indian Ocean, with descriptions of two new species.
Three species of Helcogramma from the Indian Ocean that form a monophyletic group are recognised: Helcogramma steinitzi Clark (Red Sea and Gulf of Oman), H. rosea n. sp. (Andaman Sea and Sri Lanka) and H. microstigma n. sp. (East African coast and adjacent islands). Helcogramma microstigma is distinguished from the other two species by a head profile of 67[degrees]-72[degrees] (about 60[degrees] in the other two species) and a long orbital cirrus (short and triangular in the other two species) and clusters of micromelanophores on the dorsum at the ends of the second and third dorsal fins of mature males (absent in the other two species). Helcogramma steinitzi has melanophores only on the distal half of the anal fin (in the other two species melanophores cover the entire fin) and a narrow interorbital (16.6 in head length). Helcogramma rosea has a sharper head profile of 56[degrees]-62[degrees], similar to that of H. steinitzi, but is distinguished from it by anal fin pigmentation, a wider interorbital (about 15 in head length) and smaller size (maximum SL 33 mm cf. 47 mm for H. steinitzi). The three species in the group share a number of putative synapomorphies including very close-set first two dorsal-fin spines and densely packed micromelanophores on the membrane between these first two spines of both males and females. The close similarity of the species, their distribution, and comparisons to other tripterygiid species groups are discussed.
Beschrieben werden drei Arten der Gattung Helcogramma aus dem Indischen Ozean, die einer monophyletischen Gruppe angehoren: Helcogramma steinitzi Clark (Rotes Meer und Golf von Oman), H. rosea n. sp. (Andamanen-See und Sri Lanka) sowie H. microstigma n. sp. (ostafrikanische Kuste und angrenzende Inseln). Helcogramma microstigma unterscheidet sich von den beiden anderen Arten durch sein Kopfprofil: 67[degrees]-72[degrees] (etwa 60[degrees] bei den zwei anderen) und ein langes, im Querschnitt rundes Tentakel (kurz und dreieckig bei den zwei anderen Arten) sowie Gruppen von Micromelanophoren an den Enden der zweiten und dritten Ruckenflosse bei geschlechtsreifen Mannchen (fehlt bei den anderen). Helcogramma steinitzi besitzt Melanophoren nur in der distalen Halfte der Afterflosse (die anderen beiden Arten auf der ganzen Flosse) und einen schmalen Interorbitalraum (1/16, 6 der Kopflange). Helcogramma rosea hat ein spitzeres Kopfprofil (56[degrees]-62[degrees]), ahnlich dem von H. steinitzi, unterscheidet sich aber durch Afterflossenpigmente, breiteren Interorbitalraum (etwa 1/15 der Kopflange) und die geringere Grosse (maximal 33 mm SL im Vergleich zu 47 mm bei H. steinitzi). Gemeinsam haben die drei Arten eine Reihe von Merkmalen, die wohl als Synapomorphien einzustufen sind, darunter eine sehr grosse Nahe des ersten und zweiten Ruckenflossenstachels und dicht gedrangte Micromelanophoren auf der Membran zwischen denselben beiden Flossenstacheln bei beiden Geschlechtern. Abschliessend werden die starken Ahnlichkeiten der drei Arten, ihr Vorkommen und vergleichende Merkmale anderer Tripterygiiden-Arten beleuchtet.
On a identifie trois especes d'Helcogramma de l'Ocean Indien qui forment un groupe monophyletique: Helcogramma steinitzi Clark (Mer Rouge et Golfe d'Oman), H. rosea n. sp. (Mer d'Andaman et Sri Lanka) et H. microstigma n. sp. (cote orientales de l'Afrique et les iles voisines). Helcogramma micristiga se distingue des deux autres especes par un profil de la tete de 67[degrees]-72[degrees] (pres de 60[degrees] pour les deux autres especes) et par un cirre orbital long (court et triangulaire chez les deux autres especes) et des amas de micromelanophores au bout de la deuxieme et de la troisieme dorsale de males adultes (absents chez les deux autres especes). Helcogramma steinitzi a des melanophores seulement sur la moitie distale de l'anale (dans les deux autres especes, les melanophores couvrent toute la nageoire) et un interorbital etroit (166 dans le sens de la longueur de la tete). Helcogramma rosea a un profil de tete plus pointu, de 56[degrees]-62[degrees], semblable a celui de H. steinitzi, mais s'en distingue par la pigmentation de l'anale, un interobital plus large (d'environ 15 dans le sens de la longueur de la tete) et une taille plus petite (LS 33 mm maximum cf. 47 mm pour H. steinitzi). Les trois especes du groupe partagent un nombre de synapomorphies incluant deux epines de la dorsale tres rapprochees et des micromelanophores en formation dense sur la membrane entre ces deux premieres epines, tant chez les males que chez les famelles. La ressemblance etroite des especes, leur distribution et des comparaisons avec d'autres especes de Tripterygiides sont discutees.
Tre specie del genere Helcogramma presenti nell'Oceano Indiano formano un gruppo monofiletico: Helcogramma steinitzi Clark (Mar Rosso e Golfo di Oman), H. rosea n. sp. (Mare delle Andamane e Sri Lanka) e H. microstigma n. sp. (costa orientale dell'Africa e isole adiacenti). Helcogramma microstigma si distingue dalle altre due specie per il profilo del capo di 67[degrees]-72[degrees] (circa 60[degrees] nelle altre due specie), un lungo cirro orbitale (corto e triangolare nelle altre due specie) e un complesso di micromelanofori sul dorso all'estremita della seconda e della terza pinna dorsale dei maschi maturi (assenti nelle altre due specie). Helcogramma steinitzi ha melanofori solo nella meta distale della pinna anale (nelle altre due specie i melanofori ricoprono l'intera pinna) e lo spazio interorbitale stretto (16.6 nella lunghezza della testa). Helcogramma rosea ha il profilo del capo piu ripido, di circa 56[degrees]-62[degrees], che ricorda quello di H. steinitzi, ma si distingue da quest'ultimo per la pigmentazione della pinna anale, un piu ampio spazio interorbitale (circa 15 nella lunghezza della testa) e una taglia inferiore (SL massima 33 mm verso 47 mm per H. steinitzi). Le tre specie condividono un numero di putativi caratteri sinapomorfici, tra cui le prime due spine dorsali molto ravvicinate e micromelanofori densamente ammassati sulla membrana tra queste due spine sia nei maschi che nelle femmine. La forte somiglianza delle specie, la loro distribuzione e il confronto con gli altri gruppi di specie di tripterigidi sono discusse.
Williams & McCormick (1990) were the first to recognise a group of species within the genus Helcogramma McCulloch & Waite, 1918, that is clearly monophyletic, a number of species similar to H. fuscopinna Holleman, 1982, linked by a single synapomorphy: a blue-white line with micromelanophores that runs from the upper lip, below the eye and onto the preopercle of males and large females. They described two additional species in this group. Continuing this study, Williams & Howe (2003) described a further seven species, bringing the total number of species in the Helcogramma fuscopinna species group to 11.
In an ongoing review of the Helcogramma species of the Western Indian Ocean (Holleman, in prep.), it became clear that there are other species groups within Helcogramma that can be clearly demarcated by putative synapomorphies. One of these is the Helcogramma obtusirostre (Klunzinger, 1871) species group, with possibly as many as six species. Another is the Helcogramma steinitzi Clark, 1979 species group, which is currently recognised as comprising three species from the Indian Ocean: H. steinitzi from the Red Sea and Oman, H. rosea n. sp. from Sri Lanka and the Andaman Sea, and H. microstigma n. sp. from the east coast of Africa and adjacent islands. There are probably species in the Western Pacific Ocean that can also be assigned to this group.
The species of the Helcogramma steinitzi group, H. microstigma, H. rosea and H. steinitzi, share at least six characters, including the following: a high first dorsal fin (not unique to the group, but uncommon in Helcogramma); the first two dorsal-fin spines placed very close together (the distance between them less than half the distance between the second and third spines), and the membrane between the first two dorsal-fin spines densely covered with micromelanophores in both males and females.
All measurements were made with pin dial calipers under a binocular microscope and are given in millimeters to a single decimal place. Ratios are calculated as the number of times a given measured length is contained in either the standard length or the head length. Where measurements of interorbital width were made, calipers are not sufficiently accurate and ratios serve merely to indicate underlying differences in skull structure. The measurements of head profiles in Holleman (1982), are also fairly 'crude', but serve to indicate differences in skull structure. All counts were made under a microscope, excluding vertebrae, which were counted from X-rays. Pectoral-fin ray and lateral-line counts were made on the left side. Specimens on rare occasions have lost or gained a single ray in one of the pectoral fins. If the count was not that expected, the right side was counted, and if "normal", it was recorded; if not, the "non-normal" count was recorded. From the dorsalmost fin ray, the counts are given as the number of undivided rays, number of divided rays, number of undivided rays, e.g. 2, 7, 7. The numbers of divided and undivided rays were found to be remarkably consistent for most species.
Body scales of tripterygiid fishes are deciduous and often missing. If the last lateral-line scale on the left side was not followed by an ordinary body scale, those on the right side were counted. If neither side was complete, the count was not recorded. Most species of Helcogramma have a naked area laterally along the base of the first and often the second dorsal fins. In species in which the body scales do not extend to the base of these fins, the scales decrease in size and become very thin as they approach the fin bases. They are best seen stained with Cyanine Blue (Saruwatari et al. 1997). Nape scales, when present, and only on the side of the nape, are also best seen when stained with Cyanine Blue. Few tripterygiid species have scales in the predorsal midline. It was found that for species which do not have a fully scaled nape, such as Helcogramma microstigma, the number of transverse scale rows increases with increasing size of the fish. This means that while scales above the lateral line may not extend to the base of the second dorsal fin in apparently immature (smaller) specimens, they may do so in larger, presumably mature specimens, such as darkly pigmented males. The nape would then be referred to as scaled, and the extent of the scalation noted. Transverse scale counts are not given for the species in this study. Total lateral scales were counted as a continuation of the lateral line to the base of the caudal fin. Tripterygiids have from zero to three rows of scales of varying size on the base of the caudal fin. These are not included in the count but noted separately.
Williams & McCormick (1990) derived a method of representing dorsal element counts from X-rays. This included the number of pterygiophores without a spine between the second and third dorsal fins, zero being the condition where the first pterygiophore supporting a segmented ray does not support a spine. I do not follow this method, but indicate the number of "free" pterygiophores; i.e. carrying neither a spine nor a segmented ray. This number generally varies between zero and two and is not consistent for a species. The method of counting vertebrae follows Holleman (1982) and is the same as that of Williams & McCormick (1990). They are given as the number of precaudal + the number of caudal vertebrae, and includes the compound terminal centrum (not stated in Holleman 1982).
Mandibular pore counts follow Hansen (1986), who found that the mandibular pore patterns of Helcogramma species were consistent for a species and often diagnostic. They have been found to be so in Enneapterygius Ruppell, 1835 as well (Holleman 2005), and they are given as number of pores in left hand canal + number of symphyseal pores + number of pores in right hand canal.
A note on the distribution map: In their investigation into the historical biogeography of Indo-western Pacific coral-reef fauna, Santini & Winterbottom (2002) divided the Indo-western Pacific into a number of biogeographic areas with tentative boundaries. These areas for the Western Indian Ocean are shown on the distribution maps, in order to give some idea of the distribution of species in relation to the different biogeographic areas.
Tables I and II compare the meristics and morphometric values of the three species. In the tables and the text, means are given in square brackets. The following abbreviations are used in the text and tables: standard length--SL; head length--head; maxilla length--max; mandibular--mandib.; interorbital width--I.O.; number of vertebrae--vert.; total number of lateral scales--latl.
Key to the species of the Helcogramma steinitzi group
1a. Anal fin with melanophores on distal half only; H. steinitzi (Red interorbital relatively narrow, mean 16.6 in Sea to Persian head length; pale saddles at end of second and Gulf) third dorsal fins white in life; LL usually with fewer than 25 scales; maximum recorded SL 47 mm 1b. Anal fin with melanophores to base of fin; 2 interorbital relatively broad, mean 15 in head length; pale saddles at end of second and third dorsal fins yellow or pink in life LL usually with more than 25 scales 2a. Orbital cirrus long and narrow, about half eye H. microstigma diameter; head profile relatively blunt, about (Comoro Islands, 70[degrees]; pale (yellow in life) saddles at N. Madagascar and ends of second and third dorsal fins with Mozambique) micromelanophores; maximum recorded SL 34.5 mm 2b. Orbital cirrus small, short and triangular, H. rosea (Andaman with length equal to base; head profile Sea and Sri relatively sharp, about 60[degrees]; pale Lanka) saddles (pink in life) at end of second and third dorsal fins without micromelanophores; maximum recorded SL 33.2 mm
Helcogramma microstigma n. sp. (Figs 1-2, 5)
Holotype: SAIAB 73754, male, 29.0 mm SL; Bazaruto Island, Mozambique, off Bazaruto lighthouse, 21[degrees]30' S 35[degrees]30' E, depth 9-10 m, sand with patches of coral; coll. P. C. Heemstra & M. van der Berg, 13 August 2002.
Paratypes: ROM 73409, 5: 21.3-23.0 mm; ROM 73410, 31.3 mm, all from Comoro Islands, coll. R. Winterbottom and others; ROM 76683, 27.4 & 28.1 mm; SAIAB 73753, 13: 24.8-29.0 mm; USNM 381379, 2: 26.5 mm, Bazaruto Island, Mozambique; same collection as holotype; USNM 307834, 30.3 mm, Nosy Be, Madagascar, coll. J. Paxton & D. Cohen, 9 November 1988.
Non-type specimens: SAIAB 1745, 34.0 & 34.5 mm and SAIAB 1823, 29.1 mm, Inhaca Island, Mozambique, coll. J. L. B. & M. M. Smith.
A medium-sized species of the Helcogramma steinitzi group, with a maximum recorded SL of 34.5 mm; usually with 26-28 lateral-line scales and 4 + 1 + 4 mandibular pores; first dorsal fin of males taller than the second, the first two spines set close together with micromelanophores on the membrane between them, a long, pointed orbital cirrus, about half pupil diameter in length, and a relatively blunt head with a profile of about 70[degrees].
Dorsal fins III + XIII + 10-11; anal fin I, 18-20 (usually 19-20 rays); pectoral fins 15-16: 2, 6, 7 or 2, 7, 7. Lateral line pored scales 24-31 (usually 26-28), ending below middle of third dorsal fin; total lateral scales 38 (rarely 37 or 39). Vertebrae 11 + 25; usually 1 free pterygiophore between second and third dorsal fins (a few specimens with 0). Mandibular pores 4 + 1 + 4 (Fig. 1c; rarely 3 + 1 + 3; holotype 3 + 1 + 4). Head narrow and elongate, its length 3.1-3.6 [3.4] in SL; eye 2.6-3.1 [2.9], maxilla 2.1-2.5 [2.2], snout 3.1-3.9 [3.5], interorbital 12.6-18.0 [14.9] in head length; head profile acute, 67[degrees]-72[degrees] [69[degrees]].
[FIGURE 1 OMITTED]
Sides of nape scaled, but scales do not extend to base of first dorsal fin anteriorly; 2 or 3 rows of scales on base of caudal fin; scales on underside of peduncle; scales do not extend to base of anal fin anteriorly. Pelvic-fin rays united by membrane for two-thirds length of shorter, half length of longer ray, longest ray reaching about 80% of distance to vent in females, 90% in males. First dorsal fin of males triangular, with first spine taller than second dorsal fin, in females slightly lower than second, in both sexes first two spines closer together than half distance between second and third spine. Maxilla reaches vertical through anterior margin of pupil. Oral margin of upper lip crenulate; lower labial folds narrow. Broad patch of slightly recurved, conical teeth in front of both jaws, with single row of enlarged teeth on outer margin, narrowing to single row on either side. Patches of teeth on vomer and palatines. Orbital cirrus simple and pointed, about half pupil diameter in length.
Live colour (based on freshly preserved material). Males dark pink with three orange blotches at base of second dorsal fin and three at base of third dorsal fin. Series of dark pink blotches along lateral midline, with alternating diffuse dark and pale areas just below the lateral line; dark brown bar across the peduncle. Anal fin with eight dark pink spots along base; belly white. Head slate grey to black below ventral margin of eye, with orange spots above. Membrane between first two dorsal-fin spines orange and black, remainder of first dorsal fin black (see preserved colour below); second dorsal fin black and orange basally with narrow black margin; third dorsal fin similar but paler. Anal fin black with orange along rays corresponding to colour on body. Caudal fin pinkish with orange at base of rays. Pectoral fins with orange on middle and upper rays; pelvic fins without colour. Females very similar to males but lack the black on the head and median fins. Large females also have a narrow dark bar--more a line--across the caudal peduncle at the base of the caudal-fin rays.
Colour in alcohol: Body of males with irregular groups of melanophores suggestive of banding above the midline; cluster of few melanophores adjacent and posterior to genital papillae. Head below ventral margin of eyes with dense and evenly spread melanophores extending to base of pectoral-fin rays and along throat to base of pelvic fins. Top of head with few, small melanophores, interorbital area immaculate. First dorsal fin evenly marked with densely packed melanophores, those on membrane between first two spines very small; basal half of second dorsal fin black, followed by a paler band and with narrow black band along margin; third dorsal fin similar. Distal third of caudal fin dark, spotted with melanophores, as are upper and lower rays. Anal fin black with many small and evenly-spaced melanophores on both rays and membranes. Pelvic-fin membrane of large males with cluster of small melanophores in middle. Pectoral-fin rays with some spotting. Banding on body more obvious in females, the patches of melanophores extending to just below lateral midline. Large females with narrow dark bar across peduncle at base of caudal fin (not shown in Fig. 2). Scattered melanophores on head and a small cluster on lower pectoral-fin base. First dorsal-fin membrane between first two spines as for males, with many micromelanophores, but not as dark.
[FIGURE 2 OMITTED]
Distribution (Fig. 5)
The species is known from the Comoro Islands, northern Madagascar and Bazaruto and Inhaca Islands, Mozambique.
The species is named for the micromelanophores on the membrane between the first two dorsal-fin spines, characteristic of the species group.
Helcogramma microstigma occurs throughout its range sympatrically with H. fuscopinna, from which H. microstogma can be distinguished by its tall, triangular first dorsal fin with micromelanophores, a lower number of pectoral-fin (16 vs. 17) and anal-fin rays (19 or 20 vs. 21), and the lack of the typical H. fuscopinna blue-white line with micromelanophores below the eye. In the Comoro Islands H. microstigma also occurs sympatrically with an as yet undescribed species from which it can also be distinguished by its tall first dorsal fin with micromelanophores, and by a higher lateral-line scale count--more than 24 vs. usually 20-23 for the undescribed species.
The three species of the group can be separated as follows:
The anal fins of H. microstigma and H. rosea are entirely covered with melanophores, whereas that of H. steinitzi has melanophores only on the distal half.
The orbital cirrus of H. microstigma is longer than for the other two species, being about half eye diameter, while the other two have a very small triangular cirrus that is as long as it is wide.
H. steinitzi has a large, somewhat flattened head, with a sharper profile (mean 60[degrees]) than H. microstigma (mean 70[degrees]), reflected in the proportions of eye diameter and maxilla length to head length--eye 3.2 vs. 2.9 in head length, maxilla 2.0 vs. 2.2 in head length, and a narrower interorbital distance than the other two species (mean of 16.6 for H. steinitzi in head length vs. about 15).
Mature females of H. rosea and H. steinitzi have a series of subcutaneous spots along the base of the anal fin; absent in H. microstigma.
Mature males of H. rosea have patches of micromelanophores underlying the yellow saddles below the first and second dorsal fins, absent in the other two species.
H. steinitzi generally has fewer lateral-line scales than the other two species. Recognising that lateral-line scale counts for several species of Helcogramma are highly variable, more specimens will undoubtedly show the numbers cluster around a mode in the low 20s for H. steinitzi, compared to modes in the mid- and high-20s for the other two species.
H. steinitzi is a much larger and more robust species than the other two, attaining 47 mm SL, compared to maximum recorded length of slightly less than 35 mm for mature males.
Helcogramma rosea n. sp. (Figs 3-5)
Holotype: ROM 76679, male, 34.4 mm SL, Ko Hi, Phuket, Thailand, 7[degrees]44'31" N 98[degrees]22'32" E, depth 0-5 m, patch reefs on sand with stands of Acropora; coll. R. Winterbottom and others, 12 November 1993.
Paratypes: ROM 76680, 3: 27.6-30.0 mm, same collection as holotype; ROM 76681, 10: 21.9-32.0 mm; ROM 76682, 11: 24.3-33.2 mm; SAIAB 75326, 4: 25.3-34.1 mm (ex ROM 76682), all from Phuket, Thailand, coll. R. Winterbottom and others; USNM 222915, 5: 22.2-26.4 mm; USNM 228942, 3: 21.4-23.2 mm; USNM 222919, 3: 21.4-30.8 mm, coll. Koenig, April 1970; USNM 222916, 3: 21.1-23.7 mm, coll. P. C. Heemstra, 1 October 1969, all from Trincomalee, Sri Lanka.
A medium-sized species of the Helcogramma steinitzi species group with a maximum recorded length of 34.8 mm. First dorsal fin of males equal in height to the second, slightly lower in females, and with micromelanophores on the membrane between the first two spines; males with three narrow, yellow saddles, one below the anterior of the second dorsal fin, one below the end of the second dorsal fin and one below the end of the third dorsal fin, saddles of mature males in preservative as clusters of micromelanophores; females with seven clusters of melanophores subcutaneously at the base of the anal fin, showing as brown blotches in life.
Dorsal fins III + XIII + 10-11 (rarely 12 rays); anal fin I, 18-20 (rarely 18, usually 20 rays); pectoral-fin rays 16: usually 2, 7, 7. Lateral line pored scales 23-29 (usually 25-27); total lateral scales 36-38 (usually 37). Vertebrae 11 + 25 or 26, 0 or 1 free pterygiophores between second and third dorsal fins. Mandibular pores 3-4 + 1 + 3-4 (pore on inside of ramus small and absent in about 60% of specimens examined). Head length 3.1-4.0 [3.3] in SL; eye 2.8-3.4 [3.1], maxilla 2.0-2.3 [2.2], snout 3.1-3.9 [3.5], interorbital 12.6-18.0 (see Table I) in head length; head profile 56[degrees]-65[degrees] [60[degrees]].
Nape scaled, but scales do not extend to base of first dorsal fin anteriorly; 2 or 3 rows of scales on base of caudal fin; scales on underside of caudal peduncle; scales do not extend to base of anal fin anteriorly. Pelvic-fin rays united by membrane for half length of longer ray, longer ray extends nearly to vent in males, about 80% of distance in females. First dorsal fin of males triangular, with first spine equal in height to second dorsal fin, in females first 2 dorsal-fin spines subequal, and fin about 80% height of second dorsal fin; first two spines closer together than half distance between second and third spines. Maxilla reaches vertical through centre of pupil. Broad patch of teeth in front of both jaws, narrowing to single row on either side; vomer and palatines with patches of teeth. Orbital cirrus small, triangular and rounded, a little longer than wide.
[FIGURE 3 OMITTED]
Live colour: (from photographs of fresh specimens from Phuket by R. Winterbottom--see note below). Males with red body and three small, yellow saddles, first below anterior of second dorsal fin, second below end of second dorsal fin and third below end of third dorsal fin, with line of yellow dots and dark brown dashes along lateral line and narrow dark bar across the peduncle; belly spotted red. Head reddish above, dark brown behind eyes and to posterior edge of opercle, pale with dark spots below eyes, to pelvic-fin base; dark-brown, oblique bar from lower margin of eye with pale blue anterior to and below eye, and bright yellow spot immediately behind eye. Iris red with yellow spots, nasals and centre of upper lip brown. First dorsal fin pale with brown and red spots; second with red spots basally and brownish margin; third with red spots basally and red and black along margin. Caudal fin mostly deep pink with small black spots antero-ventrally. Anal fin spotted with red and black, the black darkest along margin. Pectoral-fin base brown with two pale blue spots at centre and at lower edge, fin entirely red with three pale "bars", colour on rays only. Pelvic fins pale, red basally.
Females with light cream body, greenish above lateral line, with series of chocolate brown blotches along lateral line, pairs of brown "saddle" marks, three below second dorsal fin, two below third dorsal fin and one on peduncle, last half-pair forming narrow bar across peduncle; anal fin with seven subcutaneous, brown blotches along base. Head, nasals, upper lip, preopercle and opercle mottled brown and cream, pale cream below eye with some brown marks. First dorsal fin with brown, second and third with brown on spines and rays roughly corresponding to "saddles" on dorsum. Caudal fin pale with a little colour along the rays; anal fin with spots along margin, colour on rays only.
Colour in alcohol: Males with pale body with clusters of melanophores along midline, last forming a narrow bar across caudal peduncle; scattered melanophores above midline, in large specimens with groups of micromelanophores where yellow saddles are in life; cluster of small melanophores adjacent and posterior to genital papillae. Head with scattered melanophores on top and in interorbital area; closely and evenly spaced melanophores below eye, which continue onto the anterior of belly, either side of pelvic-fin base, and onto pectoral-fin base, where colour is darkest at base of central rays. First dorsal fin with densely spaced micromelanophores on membrane between first two spines, other membranes with few large spots; second dorsal fin with broad band of melanophores at base and narrow band along margin; third similar to second, but lighter. Anal fin with many small melanophores on membranes and rays, darker along the margin in smaller specimens, evenly spread across entire fin in large specimens. Pectoral fins with rows of micromelanophores on some rays, suggestive of two bars across fin.
Mature females are very similar in colour to males, melanophores on dorsum suggestive of short bars with clusters along midline and series of subcutaneous spots along base of anal fin. Head with few melanophores, most notably clusters on upper lip either side of symphysis, and semicircular cluster, open anteriorly, on opercle. First dorsal fin as in males; second and third with small melanophores on elements, continuous with short bars on body. Pectoral--fin base with two clusters of melanophores, one dorsally and one ventrally on base.
[FIGURE 4 OMITTED]
Note: The photographs of a male and female Helcogramma lacuna in Williams & Howe (2003: 165) and taken by Rick Winterbottom in Phuket are not of H. lacuna Williams & Howe, 2003, but are of Helcogramma rosea, described above. The live colour of H. lacuna is not known (Williams pers. comm.).
Distribution (Fig. 5)
The species is known from Sri Lanka and the Andaman Sea.
Comment on Sri Lankan compared to Andaman Sea specimens
Tables I and II show the morphometric and meristic values for the specimens from Sri Lanka and those from the Andaman Sea separately. There are both differences and similarities between the two 'populations'. The differences are as follows:
1. The Sri Lankan specimens show an even division in the number of third dorsal-fin rays (6 and 7) compared to Andaman Sea specimens, which have four times as many individuals with 11 rays as with 10. This may, however, be a result of having studied a small number specimens rather than a reflection of reality.
2. The Andaman Sea specimens show a greater range in number of lateral-line scales than the Sri Lanka specimens, but this again may be result of the number of specimens available. Several--but not all--Helcogramma species show considerable variation in lateral-line scale counts and only when many specimens are to hand can one get a clear idea of the median number of lateral-line scales.
3. There seems to be a significant difference in caudal vertebral counts between Andaman Sea and Sri Lanka specimens (predominantly 25 vs. predominantly 24) that may be due to environmental factors.
The similarities that led me to consider the two 'populations' as a single species are:
1. The same head profile of specimens from the two areas, which though similar to the head profile of H. steinitzi (which for other reasons is a distinct species) is significantly different to specimens from the Western Indian Ocean (H. microstigma), and reflects differences in cranial osteology.
2. The similarity in melanophore patterns, particularly of the patches of micromelanophores on the body at the posterior ends of the second and third dorsal fins of mature males and the presence of subcutaneous spots at the base of the anal fin of large females. These are also present in H. steinitzi, which, as noted above, is a separate species for other reasons. To the best of my knowledge, there are no colour photographs of this species from Sri Lanka.
These are felt to provide sufficient reason to consider the two 'populations' as a single species.
Helcogramma rosea occurs sympatrically with H. springeri Hansen, 1986 and H. lacuna Williams & Howe, 2003 at Phuket, and with several other Helcogramma species at Sri Lanka. Helcogramma rosea can be distinguished from the other species at Phuket by its tall first dorsal fin with the close-set first two dorsal-fin spines with micromelanophores on the membrane between them. Helcogramma springeri also has a tall first dorsal fin but lacks the micromelanophores, lacks an orbital cirrus and has a shorter lateral line, of 12-14 scales vs. more than 20 for H. rosea. Helcogramma lacuna is a member of the Helcogramma fuscopinna species group and is distinguished by a line of micromelanophores that runs from the upper lip, below the eye, onto the preopercle.
In Sri Lanka the species can be distinguished from both H. billi Hansen, 1986 and H. ellioti (Herre, 1944) which have lateral lines that extend to the base of the caudal fin, from H. shinglensis Lal Mohan, 1971 by the number mandibular pores (3 symphyseal pores vs. 1 for H. rosea) and from H. shinglensis and an as yet undescribed species by the tall first dorsal fin with micromelanophores.
Helcogramma steinitzi Clark, 1979 (Figs. 5-8)
Helcogramma steinitzi Clark, 1979: 88, fig. 8, Pl. II-V (type locality: Red Sea); Hansen 1986: 347; Randall 1995: 310, fig. 873.
HUJ 17628, 37.2 & 38.6 mm, Ras Burka, and HUJ 18280, 33.8 mm, Elat, Red Sea; USNM 205824, 7: 21.1-38.0 mm, USNM 205833, 17: 16.4-35.6 mm, and USNM 205791, 8: 20.5-25.2 mm, all paratypes, all from Aqaba, Red Sea, all collected by V. G. Springer and others, 1969.
Description (partially from Clark 1979 and Randall 1995)
Dorsal fins III + XII-XIV + 10 or 11 (second dorsal fin usually with
XIII spines); anal fin I, 19-21 (usually 20); pectoral fins usually 16: 3, 7, 6. Lateral line 20-26 pored scales, ending below the first five rays of the third dorsal fin; total lateral scales 37-40 (usually 38; 37-41, Clark 1979). Vertebrae: 11 + 25 (rarely 26); 1 free pterygiophore between second and third dorsal fins. Mandibular pores 3 + 1 + 3 (Fig. 8c). Head length 3.1-3.5 [3.2] in SL; eye 3.0-3.4 [3.2], maxilla 1.9-2.1 [2.0], snout 3.0-3.7 [3.4], interorbital 14.1-20.0 [16.6] in head length; head profile acute, 56[degrees]-59[degrees] [57[degrees]].
A large species, the longest recorded at 47 mm SL, with a large, somewhat flattened Trigla-like head. Nape scaled, belly naked, scales do not extend to base of first dorsal or anal fins; 1 or 2 rows of scales at base of caudal fin. Pelvic-fin rays united by membrane for half length of shorter ray, longer ray reaches vent. First spine of first dorsal fin of males about as long as longest spine of second dorsal fin, in females about three quarters as long; first two spines closer together than second and third spines. Mouth large, maxilla reaching vertical through posterior of pupil; orbital cirrus minute, triangular, its width equal to its length.
Live colour (based on Randall 1995 and photographs by J. Randall). Body of males dark red above lateral line, many scales outlined in black, paler red below lateral line, with white flecks and indistinct black markings forming a reticulate pattern, and with eight dark blotches interspersed with white blotches along mid-side below lateral line; belly white. Head above ventral margin of eye dark red, below bluish grey with many small melanophores, and a bluish streak below eye. Membrane between first two dorsal-fin spines yellowish with black spots; second and third dorsal fins with red basal band with black spots and pale red marginal band, hyaline band between, with white on elements. Anal fin pale red, darker along margin; caudal fin pale red; pectoral fins red, bases dark grey with two oval, bluish marks, one dorsal to the other; pelvic fins pink.
[FIGURE 5 OMITTED]
[FIGURE 6 OMITTED]
Females with translucent greenish body, irregularly spotted with white, with large interconnecting red blotches, red and black spots on scale margins, forming a reticulated pattern; head greenish with numerous dark red spots and short bands, the darkest a diagonal band on the side of the snout. First dorsal fin similar to that of males; second and third similar to that of males, but with red on elements only and white on membranes; caudal fin pink; anal fin pink, darkest along margin.
Colour in alcohol: Males with head below eyes to pectoral-fin base dark grey to black, body with scattered clusters of melanophores. First dorsal fin with micromelanophores on membrane between first two spines, larger black spots on subsequent membranes, second dorsal fin with black spots on membranes basally, and third dorsal and anal fins with dusky bands along margins.
Females with a reticulate pattern of dark short bars characteristic of females of many species of the genus, as well as a series of subcutaneous clusters of small melanophores along the base of anal fin. First dorsal fin as in males, with micromelanophores on membrane between first two spines.
The only other species of Helcogramma that occurs sympatrically with H. steinitzi, H. obtusirostre has a smaller head (3.3-3.7 in SL vs. 3.1-3.5 for H. steinitzi), a blunter snout, 18 or 19 anal-fin rays (usually 20 for H. steinitzi) and a lower first dorsal fin in males (about half the height of the second, equal to or higher than the height of the second for H. steinitzi). In life the males of the two species can be easily distinguished. Mature H. obtusirostre males are much darker than H. steinitzi males, often nearly black, with two distinctive pale, narrow saddles and a blue line from the corner of the mouth to the hind margin of the preopercle.
[FIGURE 7 OMITTED]
[FIGURE 8 OMITTED]
Distribution (Fig. 5)
Helcogramma steinitzi has been recorded from the Red Sea, Oman, the Persian Gulf (Krupp & Almarri 1996).
Gill & Kemp (2002: 165) state that the reported wide distribution of many shore fishes in the Indo-Pacific may be incorrect and argue convincingly that well-diagnosed intraspecific forms should be accorded full specific status. They note particularly that many 'forms' of widely distributed species, which differ little if at all in spine, ray and scale counts, show but slight differences in colour pattern between one 'form' occurring in the Western Indian Ocean and another in the Western Pacific and that these too should be accorded specific status in preference to 'form' or subspecific rank. Thus, as we better understand particular characters, we can better re-evaluate purportedly widespread species.
In similar vein Knowlton (1993) wrote about the prevalence of sibling species in many groups of marine organisms. (Knowlton uses the terms "sibling species" and "species complexes" interchangeably.) She notes that in decapods, for example, minor colour differences are often diagnostic in sibling species. In fishes, examples are provided by the sibling species Pavoclinus pavo (Gilchrist & Thompson, 1908) and P. coerulopunctatus Zsilavecs, 2001, which, like several South African clinid species, take on the colour of their substrate but differ in facial pigmentation and depth distribution. Knowlton (1993) also emphasised that little is known about the life histories of most marine organisms, and that it has been assumed that widely distributed species are a consequence of successful long-distance dispersal, an assumption for which there are few data.
When I first described Helcogramma fuscopinna I noted the apparent wide distribution of the species, and the colour and other differences of specimens from Japan, Taiwan and the Philippines, compared to those from the Indian Ocean (Holleman 1982). Subsequently Williams & McCormick (1990) and Williams & Howe (2003) have described the specimens from Japan as Helcogramma nesion Williams & Howe, 2003, those from Taiwan as H. aquila Williams & McCormick, 1990, and those from the Philippines as H. albimacula Williams & Howe, 2003, all belonging to a Helcogramma fuscopinna species group.
The three species Helcogramma microstigma, H. rosea and H. steinitzi may be considered as different forms of a single, widely distributed species, on the basis of their close similarity in colour pattern and meristic values. They do however, occur in separate geographic areas (with the proviso noted below about areas in the Indian Ocean where the fish fauna is poorly known) and differ in small, but sufficient ways to warrant being accorded full specific status. These three species form a monophyletic group, sharing the following putative synapomorphies:
1. The distance between the first two dorsal-fin spines less than half the distance between the second and third spines.
2. The origin of the first dorsal over the posterior margin of the preopercle.
3. The supraoccipital sensory canal forms an open 'V'-shape anterior to the first dorsal-fin spine (compared to a flattened curve for other species).
4. Micromelanophores on the membrane between the first and second dorsal-fin spines of both males and females.
The forward placement of the first dorsal fin, the closely set first two spines and the 'V'-shaped supraoccipital sensory canal have not been seen in any other Helcogramma species, but may yet be found. The three species also share the following two characters which are not unique to them:
1. The first dorsal fin of males equal to or higher than the second, that of females a little lower than that of males.
2. All three species are reddish in colour, with similar details of colour pattern, and mature males of all three species have melanophores around the genital papillae.
A high first dorsal fin is uncommon amongst Helcogramma species, and is recorded for only five other species of more than 40 in the genus. The general red body colour of the males is also not unique and is found in a number of other species. However, the males of the three species do have very similar colour patterns: the alternating dark and light areas along the lateral line; the light "saddles" below the dorsal fins; the dark basal and marginal bands on the second and third dorsal fins and the dark anal fin; the dark lower portion of the head (in all three species melanophores extend onto the belly on either side of the pelvic-fin base), the bluish cheeks, with the darker oblique bar below the eye, and the two bluish areas on the upper and lower pectoral-fin base.
Distribution patterns. In their investigation into the historical biogeography of Indo-western Pacific coral-reef fauna, Santini & Winterbottom (2002) divided the Indo-western Pacific region into a number of biogeographic areas, with tentative boundaries. These areas for the Indian Ocean are shown on the distribution map, which shows that the three species occur in distinctly separate biogeographic areas. There are however, areas in the Indian Ocean where shore fishes have not been recently collected (e.g. Sri Lanka), have been poorly sampled (e.g. Madagascar, the Andaman, Laccadive and Mentawi Islands, and many places along the east coast of Africa) or never collected at all (e.g. the Nicobar Islands), resulting in an incomplete understanding of shore fish distributions. Thus, for example, Helcogramma rosea occurs at Sri Lanka and at islands on the west coast of the Malay Peninsula: it is reasonable to expect the species to occur in the Andaman and Nicobar Islands as well.
The Comoro Islands form the boundary between Santini & Winterbottom's (2002) Somalian and Natal basins (ibid. 196); these islands may fall into either one or the other of the areas. These authors draw their boundary to the south of the islands (followed in this paper), a hypothesis that needs to be tested by a more detailed understanding of shore fish distributions. Only that will determine whether Helcogramma microstigma occurs in one or two areas. Helcogramma steinitzi clearly does occur in two areas, though Winterbottom (1985) suggested that the Red Sea area is further divided into southern and northern areas.
Species groups. In his review of the tripterygiid fishes of the Western and Central Pacific, Fricke (1997) divides both Enneapterygius and Helcogramma into a number of species groups. These groups are largely--and tenuously--based on the number of lateral-line scales and dorsal- and anal-fin counts, and sometimes some colour characteristics. For example, the Enneapterygius elegans (Peters, 1876) species group is "characterized by a relatively long anterior lateral line series, a low first dorsal fin in both sexes, and the caudal peduncle at least in one sex with a narrow vertical black streak or 1-2 black blotches" (ibid. 181). This latter character is absent in E. rhothion Fricke, 1997; E. rhabdotus Fricke, 1997 has a broad oblique black bar, and E. larsonae Fricke, 1997 has three spots, all assigned to this group. The Enneapterygius hemimelas (Kner & Steindachner, 1867) species groups is "characterized by a medium body size, a relatively long anterior lateral line series, males with a dark head, and a low first dorsal fin in both sexes" (ibid. 217). Considering the wide variation Fricke (1997) records for the number lateral-line scales in the anterior series, 14-20 for E. elegans and 13-20 for E. hemimelas, and a low first dorsal fin, which is common for most the 50 or more Enneapterygius species. These do not seem particularly useful characters.
Similarly the Helcogramma obtusirostre species group is characterised by, "a medium to large body size, 1-9 symphyseal mandibular pores and a relatively high number of lateral line scales" (ibid. 463) Fricke (1997) includes in this group Helcogramma capidatum Rosenblatt, 1960, H. fuscipectoris Fowler, 1946, H. obtusirostre, H. steinitzi and H. trigloides (Bleeker, 1858) (see below).
Since many species of tripterygiids have very similar meristic values, Williams & McCormick (1990), Williams & Howe (2003) and this study suggest that live colour patterns are more reliable both for identifying tripterygiid species and for grouping them. However, for a species group (a 'taxon' in an informal sense) to have any phylogenetic meaning its members must share one or more derived characters.
On this basis at least five species groups within the Tripterygiidae can be currently be recognised: the Helcogramma steinitzi group discussed in this paper, the H. fuscopinna group of Williams & McCormick (1990), the H. obtusirostre group (Holleman in prep.) and two groups within Enneapterygius: a number of species similar to E. hemimelas, and a number of species similar to E. tutuilae Jordan & Seale, 1906.
The species included in each group share one or more derived characters. Those of the Helcogramma steintizi group have been fully described above. H. fuscopinna group species have a blue-white line below the eye of both males and large females, with micromelanophores, and the intense black--or entirely black--margins to dorsal and anal fins in males. In males of the H. obtusirostre group species a blue line runs from the corner of the mouth to the posterior margin of the preopercle. This group includes H. obtusirostre, H. ascensionis Lubbock, 1980, H. shinglensis, an undescribed species from the east coast of Africa, H. fuscipectoris from Japan, and possibly three other species in the Western Pacific.
Enneapterygius hemimelas group species have the body (including dorsal and anal fins) divided into two distinct colour areas, anteriorly and posteriorly, with the caudal fin the same colour as the posterior section of the body, the position of the dividing line differing between species. Species that can probably be included are E. hemimelas, E. bahasa Fricke, 1997, E. clea Fricke, 1997, E. nigricauda Fricke, 1997 and E. similis Fricke, 1997. Species of the E. tutuilae group share a tall first dorsal fin (not unique to the group) and a distinct black blotch on the margin of the second dorsal fin, in both sexes. Holleman (2005) noted that there are two colour forms of E. tutuilae, a brown and a green, which may well be separate species. Clark (1979) described a new species (E. altivelis) from the Red Sea which was synonymised with E. tutuilae by Fricke (1997) and followed by Holleman (2005), but which is probably a valid species. It is not known how many species can be included in this group; E. tutuilae is widespread in the Western Pacific Ocean.
There is no doubt that further detailed study of the live colour patterns of the species in these two speciose genera will reveal that species presumed to be widespread are in fact more than a single species, also that these species can be grouped into larger monophyletic species groups.
Jeff Williams of the Smithsonian Institution kindly arranged specimens for loan, particularly the paratypes of Helcogramma steinitzi, and provided valuable comments on the study as it was progressing. Rick Winterbottom, Royal Ontario Museum, originally arranged the fieldwork in the Comoro Islands and Phuket, Thailand, and subsequently provided specimens and photographs of Helcogramma microstigma and H. rosea. Jack Randall gave permission to use his photographs of H. steintizi. Without the colour photographs this study would have been much more difficult. Elaine Heemstra's excellent drawings have added essential details not available from photographs. I am particularly grateful for Kate Moots' valuable comments on and careful editing of the manuscript, and Rick Winterbottom smoothed out a number of wrinkles. Research facilities are generously provided by the South African Institute for Aquatic Biodiversity.
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South African Institute for Aquatic Biodiversity, Private Bag 1015, Grahamstown, 6140 South Africa. E-mail: firstname.lastname@example.org
Received: 08 April 06--Accepted: 25 July 06
Table I. Comparative meristic counts and morphometric measurements for Helcogramma microstigma, H. rosea and H. steinitzi. Anal-fin Total Specie D2 spines D3 rays rays LL latl. H. microstigma 13 10, 11 19, 20 24-30 38 n = 26 rarely 14 (50/50) rarely 18 rarely 37, 39 H. rosea 13, 14 10, 11 19, 20 23-27 36, 37 Sri Lanka usully 13 (1 with12) usually 20 n = 14 H. rosea Andaman 14 11 18-20 23-29 36-38 Sea rarely 10 usually 20  n = 25 H. steinitzi 13 11 20 20-26 38 n = 26 rarely 14 rarely 10 rarely 19 Mandib. Head SL/ Specie pores Vert. profile Head H. microstigma 4+1+4 11+25-26 67-72[degrees] 3.1-3.6 n = 26 rarely  [69[degrees]] [3.4] 3+1-3 H. rosea 3 or 4+1+ 11+25-26 56-62[degrees] 3.2-3.4 Sri Lanka 3 or 4  [60[degrees]] [3.3] n = 14 H. rosea Andaman 3 or 4+1+ 11+25-26 57-62[degrees] 3.1-4.0 Sea 3 or 4  [59[degrees]] [3.3] n = 25 H. steinitzi 3+1+3 11+25-26 56-59[degrees] 3.1-3.5 n = 26 rarely  [57[degrees]] [3.2] 4+1+4 Head/ Head/ Head/ Head/ Max. Specie Eye Max. Snout I.O. size H. microstigma 2.6-3.1 2.1-2.5 3.1-3.9 12.6-18.0 34.5 n = 26 [2.9] [2.2] [3.5] [14.9] mm H. rosea 2.8-3.2 2.0-2.3 3.3-3.9 13.5-17.0 30.8 Sri Lanka [2.9] [2.2] [3.7] [15.3] mm n = 14 H. rosea Andaman 2.8-3.4 2.1-2.3 3.1-3.9 12.6-18.0 33.2 Sea [3.1] [2.2] [3.5] [14.9] mm n = 25 H. steinitzi 3.0-3.4 1.9-2.1 3.0-3.7 14.1-20.0 47 n = 26 [3.2] [2.0] [3.4] [16.6] mm * Maximum size recorded by Clark (1979). Table II. Fin-element, lateral-line scale and vertebral count distributions for Helcogramma microstigma, H. rosea and H. steinitzi. Lateral- D2 spines D3 rays Anal-fin rays line scales Species 12 13 14 10 11 12 18 19 20 20 21 22 23 H. microstigma 1 24 1 13 13 3 9 12 H. rosea 1 10 3 7 6 1 2 11 3 Sri Lanka H. rosea 1 23 3 6 23 1 7 20 1 Andaman Sea H. steinitzi 1 23 2 4 22 2 23 2 3 2 2 Lateral- Vertebrae: line scales Pre + caudal vert. Species 24 25 26 27 28 29 30 31 11+ 25 26 H. microstigma 2 1 4 5 4 1 1 1 17 15 1* H. rosea 3 2 3 1 14 10 4 Sri Lanka H. rosea 1 2 6 4 3 1 18 3 14* Andaman Sea H. steinitzi 1 3 2 20 17 3 * One specimen with 24 caudal vertebrae
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|Publication:||Aqua: journal of ichthyology & aquatic biology|
|Date:||Jul 1, 2006|
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