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Pisonia calafia (Nyctaginaceae) species nova from the Baja California Peninsula, Mexico.

Personnel of the herbarium at CIBNOR have been collecting plants in several areas of the Baja California Peninsula as part of their mission to compile a catalogue of the coastal flora. In 1997, an isolated vegetative specimen of a shrub (M. Dominguez 1694,1771) was found and identified tentatively as Pisonia sp., since the leaves were somewhat similar to plants of this genus; however, they did not match the two species of Pisonia that are known from Baja California: P. flavescens Brandegee and P. capitata (S. Wats.) Standl.

In the summer of 2009, a population of 30-40 plants of this still unknown species was located. This population was visited regularly until flowers and fruits were available for collecting and complete identification. Close morphological study revealed that both flower perianths, staminate (campanulate) and pistillate (urceollate), as well the inflorescences in headlike cymes, show affinity with Pisonia. However, compared to other described Pisonia species, the anthocarp anatomy is somewhat different, as the fruits are not ribbed (slightly sulcate when immature) and lack glands or warts. Another notable difference is that the fruit-supporting structures (peduncle and pedicels) are shorter than the same structures in the other peninsular species of Pisonia. Given these distinctive characteristics, the authors believe that this population should be considered a new species.

Pisonia calafia Leon de la Luz et Levin sp. nova (Fig. 1).

Frutex dioecius, confertus, spinescens, foliis ellipticis. Flores staminati 6-lobulati; flores pistillati in inflorescentiis densibus dispositi, 4-lobulati. Fructus dense velutinus, non glandularis, indehiscens, 1-seminatus, interne cotyledonibus plicatis.

Dense dioecious shrubs, erect, up to 4 m high, developing some stems from rootstocks, stems and branchlets grayish, secondary branchlets spreading in an opposite pattern at right angle; strong and straight spines 10 mm long, almost opposite in the new branchlets, absent in old stems. Leaves elliptic to broadly elliptic, 14 * 20 mm long, some cuneate at base, petioles 4-7 mm long in mature leaves, indumentum short velutinous when young, pubescent with age. Staminate inflorescences capitate, 10-12 flowered in a single raceme, peduncle to 10 mm long, pedicels up to 1 mm long; perianth campanulate, 6 mm long, 6-lobed, each lobe 1 mm long; stamens 6 alternate with perianth lobes, anthers bilocular, dorsifixed, elliptic < 1 mm diameter, extrorse, generally 1 or 2 reduced to staminodes; the fine filaments connate basally, borne at the base of a pistillode 3 mm long; lower part of the perianth reduced to 2 or 3 small involucral bracts; indumentum densely short velutinous. Pistillate inflorescences capitate, arranged in 2-5 racemes, each with 4-7 flowers, peduncles to 20 mm long, congested in anthesis, expanded after fertilization, pedicels short < 1mm long; involucre well differentiated 1-2 mm long, sacciform to urceolate in shape, very thick, with 4-5 lanceolated lobes < 1 mm long, bicolor, the basal half darker than the upper; stigma somewhat exserted, lobed and decurrent; lower part of the perianth consists of 4 lanceolate involucral bracts 1 mm long; indumentum densely short velutinous; no staminodes are present. Anthocarp, diclesium, or fruit elliptic, 10-12 * 7-8 mm, rounded at base, finely velutinous, coriaceous, indehiscent, with several parallel longitudinal lines, suggesting ancestral ribs; each fruit one-seeded, seed pisiform, 6-7 mm in diameter, black. In the plantlets, cotyledons unfold from a conduplicate position.

[FIGURE 1 OMITTED]

Type: Mexico. Baja California Sur: delegacion La Ribera, Laguna Grande, Las Lagunas, municipio de Los Cabos. 2.7 km al W del faro de Punta Arena, por la carretera costera de terraceria, km 11 entre La Ribera y Cabo Pulmo, 23[degrees]32'01.72" N, 109[degrees]29'40.88" W, 2 June 2011, J. L. Leon de la Luz 11167 (holotype: HCIB 26596 (male), 26597 (female), isotypes to be distributed, CAS, ENCB, IEB, MEXU, RSA, SD, UC).

Eponymy. The species epithet calafia was selected in honor of the beauty queen of the mythic California island, according to the book "Las sergas de Esplandian" written ca. 1510 by Garci Rodriguez de Montalvo, that supposedly inspired the conqueror Hernan Cortes to use the same name for the then recently discovered land (ca. 1535).

Related species. The mainly tropical genus Pisonia includes approximately 40 species, with the greatest species-richness in the Americas (Mabberley, 1997). Only two species of Pisonia are previously known to inhabit the Baja California Peninsula: P. capitata and P. flavescens. The former occurs in the Sierra de la Giganta, a hundred kilometers from the type location of this new taxon. However, this species is more common in the dry tropical forest of Sonora, mainland northwestern Mexico (Spellenberg, 2003). By contrast, P. flavescens is endemic to the tropical dry forest in the Cape Region of Baja California Sur. Table 1 shows the characteristics that can be used to differentiate between the Baja California Pisonia species, including this new taxon. Images of P. calafia are shown in Fig. 2.

[FIGURE 2 OMITTED]

Evolutionary affinities. To understand the evolutionary affinities of Pisonia calafia, we used the internal transcribed spacer region of nuclear ribosomal DNA, composed of ITS1, the 5.8S gene, and ITS2 (Baldwin, 1992; Baldwin et al., 1995). ITS is commonly employed in fine-scale studies of angiosperm relationships, and this region has been used for understanding relationships among closely-related species within Nyctaginaceae (Levin, 2000; Douglas and Manos, 2007). This region was amplified for one accession of Pisonia calafia (J. L. Leon-de la Luz 11167, type location), as well as an accession of P. flavescens, (Leon de la Luz s/n., Sierra Cacachilas).

Amplification was done using primers ITSleu1 (5-GTC CAC TGA ACC TTA TCA TTT AG-3'; Bohs and Olmstead, 2001) and ITSc26a (5-GTT TCT TTT CCT CCG CT-3'; Wen and Zimmer, 1996). Twenty-five microliter reactions contained 1X buffer, 3.0 mM Mg[Cl.sub.2], 0.20 mM dNTPs, 0.40 [micro]M of each primer, 1X Qiagen Q-solution (Qiagen, Valencia, CA), 0.625 units Taq polymerase, and 1[micro]L DNA. Thermal cycler conditions included an initial denaturation at 94[degrees]C for 3 min; 8 cycles at 94 [degrees]C for 30 s, 58[degrees]C down to 52[degrees]C (decreasing 2[degrees]C every two cycles) for 1 min, 72[degrees]C for 1 min; 25 cycles at 94[degrees]C for 30 s, 50[degrees]C for 1 min, 72[degrees]C for 1 min; ending with an extension at 72[degrees]C for 10 min. PCR products were cleaned and sequenced following Levin et al. (2011) with the same primers used for amplification.

The two new sequences (Pisonia calafia and P. flavescens) were cleaned using Sequencher 4.7/4.8 (Gene Codes, 1991-2007). Consensus sequences from each of these species were manually aligned (SeAl v2.0a11 (Rambaut, 1996-2002)) to a larger data set of 18 taxa from within Pisonia and across Nyctaginaceae. The family-wide phylogenetic study of Douglas and Manos (2007) guided the choice of taxa to include. ITS sequences for these additional taxa were available from GenBank (accessions: EF079454-5, EF079463, EF079475-6, EF079484-6, EF079489-90, EF079493, EF079495-6, EF079498, EF079502, EF079505, DQ317077, AF212015).

The ITS dataset was analyzed using maximum likelihood, with substitution model parameters estimated using the Akaike Information Criterion in Modeltest 3.7 (Posada and Crandall, 1998). Maximum likelihood nonparametric bootstrap analysis was conducted using the estimated model parameters, 500 full heuristic bootstrap replicates, each with 10 random-addition sequence replicates and TBR branch-swapping; the MulTrees option was disabled. Maximum likelihood bootstrap analyses were conducted using PAUP* 4.0b10 for UNIX (Swofford, 2002) on the Condor (Anonymous, 2005) computer cluster at Amherst College. Bootstrap replicates were parsed for processing using RepMaker (Wilgenbusch, 2003). Given the results of Douglas and Manos (2007), Salpianthus arenarius was defined as the outgroup.

As shown in Fig. 3, our analysis strongly suggests that the new taxon belongs within Pisonia. The genus Pisonia (excluding P. rotundata) is well supported as monophyletic (Bootstrap (BS) = 99). Within this clade, the pantropical P. aculeata + P. capitata + P. calafia are strongly supported as monophyletic (BS = 99), and P. calafia appears sister (BS = 70) to P. capitata. Although the new taxon is clearly within Pisonia, increased sampling of Pisonia species is needed to conclusively determine the closest relatives of P. calafia.

[FIGURE 3 OMITTED]

Ecology. From our field observations, some plants begin to develop flowers in June, usually the driest month, but most of the plants begin blooming just after the first heavy rain in August or September. Mature fruits were collected in November-January. At the location where 30-40 specimens were identified, no plantlet recruitment was observed. This location is at the end of a micro-basin; because there is no drainage to the sea, the micro-basin is temporarily inundated after heavy rains. A second population was found in the La Ribera arroyo, a few kilometers NW of the other site and has fewer plants than the first site. Both sites are at an elevation of 2-4 m above sea level on sandy and saline soil.

The type population grows in a coastal thorn scrubland; this vegetation type has not been previously documented in the Baja California Peninsula. Common species at the site were: Phaulotamnus spinescens A. Gray (Achatocarpaceae), Lycium brevipes Benth. (Solanaceae), Condalia globosa I.M. Jhtn. var. globosa (Rhamnaceae), Parkinsonia florida (Benth. ex A. Gray) S. Watson (Fabaceae), Randia capitata DC. (Rubiaceae), Stenocereus gummosus (Engelm.) A. Gibson et K.E. Horak (Cactaceae), and Ximenia parviflora Benth. var. glauca de Filipps (Ximeniaceae).

The Baja California flora (Wiggins, 1980) has almost 3000 species, subspecies, and varieties of vascular plants. The level of endemism is difficult to determine, given recent unpublished accounts (Rebman, pers. comm.). However, there are an estimated 800 endemic plant species on the Baja California Peninsula. Riemann and Ezcurra (2004), in an analysis of the spatial distribution of the peninsular endemics, stated that there are some "hot spots" of endemics in this region, and one of them is the Cape Region. It contains several plant communities, each with high endemism at generic, specific, and infraspecific levels (Leon de la Luz et. al., 1999). Peninsular endemism is attributed to historical vicariance events during its geological separation from the Mexican mainland and recurrent glacial-postglacial colonizations (Nason et al., 2002).

Given the limited number of individuals, low apparent level of recruitment, and restricted geographic range, the outlook for the continued persistence of P. calafia is not good. As numerous tourism projects are also under development in this area, this new taxon should be considered for IUCN and Mexican enviromental law in critically endangered status.

ACKNOWLEDGMENTS

We are grateful to Fernando Chiang Cabrera (MEXU) for the Latin translation, Danira Leon Coria prepared the illustrations, and Ira Fogel of CIBNOR made editorial improvements. We appreciate the courtesies extended by the herbarium curators of MEXU and RSA. We also greatly appreciate the participation of HCIB colleagues Raymundo Dominguez, Miguel Dominguez, and Alfonso Medel. We thank the anonymous reviewers of Acta Botanica Mexicana and CONABIO project HJ-007 for funding.

LITERATURE CITED

Anonymous. 2005. Condor Project: Condor 6.6.10. Available from: http://www.cs.wisc.edu/ condor/ Accesed October 2011.

Baldwin, B. G. 1992. Phylogenetic utility of the internal transcribed spacers of nuclear ribosomal DNA in plants: an example from the Compositae. Mol. Phylogenet. Evol. 1: 3-16.

Baldwin, B. G., M. J. Sanderson, J. M. Porter, M. F. Wojciechowski, C. S. Campbell and M. J. Donoghue. 1995. The ITS region of nuclear ribosomal DNA: a valuable source of evidence on angiosperm phylogeny. Ann. Mo. Bot. Gard. 82: 247-277.

Bohs, L. and R. G. Olmstead. 2001. A reassessment of Normania and Triguera (Solanaceae). Plant Syst. Evol. 228: 33-48.

Douglas, N. A. and P. S. Manos. 2007. Molecular phylogeny of Nyctaginaceae: taxonomy, biogeography, and characters associated with a radiation of xerophytic genera in North America. Am. J. Bot. 94(5): 856-872.

Leon de la Luz, J. L., J. J. Perez, M. Dominguez and R. Dominguez. 1999. Flora de la region del Cabo de Baja California Sur, Mexico. In: Chiang, F., M. Sousa and M. Ulloa (eds.). Listados floristicos de Mexico. Vol. 18. Instituto de Biologia, Universidad Nacional Autonoma de Mexico. Mexico, D.F. 39 pp.

Levin, R. A. 2000. Phylogenetic relationships within Nyctaginaceae tribe Nyctagineae: Evidence from nuclear and chloroplast genomes. Syst. Bot. 25: 738-750.

Levin, R. A., G. Bernardello, C. Whiting and J. S. Miller. 2011 A new generic circumscription in tribe Lycieae (Solanaceae). Taxon 60: 681-690.

Mabberley, D. J. 1997. The plant-book. A portable dictionary of the vascular plants. Cambridge University Press, Cambridge. 858 pp.

Nason, J. D., J. L. Hamrick and T. H. Fleming. 2002. Historical vicariance and postglacial colonization effects on the evolution and genetic structure in Lophocereus, a Sonoran Desert columnar cactus. Evolution 56: 2214-2226.

Posada, D. and K. A. Crandall. 1998. Modeltest: testing the model of DNA substitution. Bioinformatics 14: 817-818.

Rambaut, A. 1996-2002. Se-Al: Sequence Alignment Editor, 2.0a11. Available from: http:// tree.bio.ed.ac.uk/software/seal/ Accessed October 2011.

Riemann, H. and E. Ezcurra. 2005. Plant endemisms and natural protected areas in the peninsula of Baja California. Biol. Conserv. 1: 141-150.

Swofford, D. L. 2002. PAUP*. Phylogenetic Analysis Using Parsimony (* and Other Methods). Version 4. Sunderland, MA: Sinauer Associates.

Spellenberg, R. 2003. Nyctaginaceae. Flora of North America. Vol. 4. http://www.efloras. org/florataxon.aspx?flora_id=1&taxon_id=10617 Accessed July 2011.

Wen, J. and E. A. Zimmer. 1996. Phylogeny and biogeography of Panax L. (the ginseng genus, Araliaceae): inferences from ITS sequences of nuclear ribosomal DNA. Mol. Phylogen. Evol. 6: 167-177.

Wiggins, I. L. 1980. Flora of Baja California. Stanford University Press. Stanford. 1025 pp.

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Recibido en agosto de 2011.

Aceptado en marzo de 2012.

JOSE LUIS LEON DE LA LUZ (1,3) AND RACHEL A. LEVIN (2)

(1) Centro de Investigaciones Biologicas del Noroeste (CIBNOR), Herbario HCIB, Apdo. postal 128, 23000 La Paz, Baja California Sur, Mexico.

(2) Department of Biology, Amherst College, Amherst, Massachusetts 01002 USA.

(3) Author for correspondence: jlleon04@cibnor.mx
Table 1. Morphological traits that differentiate the Pisonia
species of the Baja California Peninsula.

Species              Pisonia flavescens       Pisonia capitata

Spines               Mainly spineless         Armed with recurved
                     or rarely with           spines 7-14 mm long,
                     stout straight           rarely absent.
                     spines 5-6 mm long.

Leaves               Leaves oblanceolate,     Leaves broadly obovate,
                     30 x 5060 mm long,       30 x 50 mm long,
                     narrowly acute to        rounded to broadly
                     acuminate at base,       cuneate at base,
                     mostly glabrous,         sparsely short-villous
                     slightly hairy           above, densely villous
                     beneath, mostly          below but becoming
                     along veins.             glabrate.

Staminate flowers    Staminate                Staminate inflorescence
                     inflorescence of         dense, puberulent,
                     congested cymules        appearing capitate,
                     appearing capitate,      10 mm diameter,
                     10 mm diameter,          peduncle 10-15 mm
                     densely puberulent,      long, many flowered,
                     peduncle 8-10 mm         pedicels very short,
                     long, many-flowered,     and stamens well
                     stamens somewhat         exserted.
                     exserted.

Pistillate flowers   Pistillate               Pistillate
                     inflorescence            inflorescence trumpet-
                     capitate, 10 mm          shaped, densely
                     diameter, densely        puberulent, 10-20
                     puberulent,              flowered, each 2-2.5
                     peduncle stout to        mm long, subtended
                     20 mm long, 1525         by a single bractlet.
                     flowered, campanulate,
                     each 2-3 mm long,
                     subtended by small
                     bractlets.

Fruits               Fruit 8-10 mm long,      Fruit 7-10 mm long,
                     angles with low,         clavate, angles with
                     stout, stipitate         rows of heavy stipitate
                     glands.                  glands, interspaces
                                              puberulent.

Fruit supporting     20-30 times longer       20-30 times longer
  structure          than unpollinated        than unpollinated
  (peduncle and      flowers.                 flowers.
  pedicels)

Species              Pisonia calafia

Spines               Armed with recurved
                     spines 10 mm long,
                     absent in old branches.

Leaves               Leaves elliptic to
                     broadly elliptic,
                     14 x 20 mm long, some
                     cuneate at base,
                     indumentum short
                     velutinous when young,
                     absent at age.

Staminate flowers    Staminate inflorescence
                     capitate, peduncle to
                     10 mm long, 1012
                     flowered, short
                     pedicellate; stamens
                     exserted, indumentum
                     densely short
                     velutinous.

Pistillate flowers   Pistillate
                     inflorescence
                     capitate, short
                     velutinous, 8-35
                     flowered in several
                     racemes, subtended by
                     4 bracts, each 1 mm
                     long, peduncles to
                     20 mm long.

Fruits               Fruit elliptic, to
                     10-12 mm, rounded
                     at the base, finely
                     velutinous, not ribbed
                     nor having glands
                     when mature.

Fruit supporting     6-10 times longer than
  structure          unpollinated flowers.
  (peduncle and
  pedicels)
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Author:Leon de la Luz, Jose Luis; Levin, Rachel A.
Publication:Acta Botanica Mexicana
Date:Oct 1, 2012
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