Phyllanthus barbarae (Euphorbiaceae), New Species from Southwestern Tamaulipas, Mexico

Abstract

Phyllanthus barbarae is described and illustrated. It is known only from the type locality in the Sierra de Guatemala, southwestern Tamaulipas, and may be related to P. galeottianus Baillon. For several years I have tried to determine the botanical name of a shrub of the genus Phyllanthus L. that I know from only one locality in southwestern Tamaulipas. The seeds, unknown until August 1984, are now available, permitting a complete description. I have concluded that this species has not yet been named, and take pleasure in associating with it the name of Mrs. Barbara Warburton of Texas Southmost College, Brownsville, Texas, who has been very helpful to me and many others in biological explorations and who has assembled documents relating to the human influences on the biota of this interesting region. Phyllanthus barbarae M. C. Johnst., sp. nov. (fig. 1).-TYPE: Mexico, Tamaulipas, Municipio de Gomez Farias, Sierra de Guatemala, Casa Piedras, 23?6'N, 99?15'W, ? 1400-1500 meters elevation, travertine at margins of stream and waterfall, total populational habitat about 1000 square meters as far as could be determined, with a total of at most 500 plants in population, 24 Aug 1984, M. C. Johnston 12851 with Eric Lautzenheiser et al. (holotype: TEX, unicate). Fruticuli 0.5-1 m alti; caules et petioli et pedicelli papillati rami tenues omnis plus minusve similares (ramificatio ergo non phyllanthoidea). Folia alterna stipulis subulatis auriculatis, lamina spathulata (5-)7-11(-15) mm longa, (3-)5-8(-11) mm lata; petioli 1-1.5 mm longi. Flores saepe (semper?) monoici saepe solitares; sepala 6; petala 0; flores masculi: pedicelli demum 1-2 mm longi; sepala ?1.5 mm longa; glanduli disci 6, ?0.2 mm longi; columna staminalis ?0.9 mm longa integra; filamenta libera nulla; antherae 3, adscendentes, rimae verticales; flores pistillati: pedicelli (fructigeri) 5-8 mm longi; sepala 2.3-3 mm longa libera obovato-oblonga, glanduli disci 6, nigropurpurascentes 0.3-0.4 mm longi, plus minusve deltoidei; styli 3, libri, partibus integris ?0.6 mm longis partibus 2-fidis ?0.3 mm longis arcte recurvatis. Fructus 3-loculatus siccus 2-2.3 mm longus, ?3.5 mm diametro; semina 1.8-2 mm longa transverse ? 1.2 mm lata badia dense tuberculato tuberculis castaneis ?0.5 mm altis ?0.5 mm diametro. Shrublets 0.5-1 m tall, apparently usually bisexual, totally glabrous except for papillae on stems, petioles and pedicels; branching not phyllanthoid, i.e., branches on single plant of highly variable length but of similar posture and degree of foliation, persistence and tendency to bear flowers; branches straight to weakly arcuate; twoto three-year-old branchlets 2-3 mm in diameter, weakly striate-angulate or the lower ones with thin, weakly exfoliating bark; branchlets of the season 0.5-1 mm in diameter with internodes (1-)2-8(-12) mm long and more or less elliptic in transection, the epidermis weakly red-brown with crowded to sparse papillae 0.3-0.6 mm long. Phyllotaxy spiral, not distichous; stipules linear-subulate, 1.1-2.3 mm long, ochraceous-green, membranous with very narrow scarious margins, each auriculate on abfoliar side of insertion; auricle ?0.1-0.3 mm long, irregularly shaped but often acute with angle of 45?-80? or at times toothed; blades spathulate, (5-)7-11(-15) mm long, (3-) 5-8(-11) mm wide, at tip rounded, at base cuneate, glabrous, ?smooth, membranous, oliveblue-green (underface duller), unlobed, the margin entire and minutely revolute (at least when dry), the tip-gland abaxial, papilliform, ?0.1-0.2 mm long; petioles 1-1.5 mm long, ?0.2 mm in diameter with sparse to dense papillae 0.3-0.6 mm long. Flowers: one or rarely two per distal axil; calyx-lobes 6 in both sexes;