Heterocentron evansii (Melastomataceae): a new species from Pico Bonito National Park, Honduras

Heterocentron evansii, known only from the higher slopes of Pico Bonito in northern Honduras, is described, illustrated, and compared with the species of subgenus Schizocentron to which it is here assigned. It is unique among congeners in having a combination of penninerved leaves, densely pubescent foliage and cauline internodes, glandular hairs on the prolonged connective of the larger anthers, and in occupying rocky ridgetops above tree line. This new species is the only Heterocentron restricted to Honduras and one of three species of Melastomataceae thought to be endemic to the country. Heterocentron, with about 28 species, is one of two genera in the Melastomataceae with a distribution restricted to Mexico and Central America (Almeda, 1993). Since it has been the subject of a recent revision (Whiffin, 1972), Heterocentron has generally been regarded as one of the better known genera of neotropical Melastomataceae. Species of this family frequently colonize windswept ridgetops throughout the Neotropics, so it comes as no surprise that exploration of these sites continues to yield new and unusual taxa. Such is the case with the new species described below, which stands apart from all described species of Heterocentron by virtue of its copiously hirsute cauline indument and densely pubescent foliage. This, coupled with its apparent restriction to an exposed, rocky ridgetop on a previously unexplored mountaintop in the largest national park in Honduras, makes it especially notable. Like Henriettella hondurensis Wurdack and Miconia celaquensis Almeda, the other two species of Melastomataceae believed to be endemic to Honduras (Almeda, 1996), the affinities of Heterocentron evansii are with congeners restricted to montane areas of Guatemala and southern Mexico. Heterocentron evansii Almeda, sp. nov. TYPE: Honduras. Athintida: narrow crest of ridge leading up to Pico Bonito from the NE (from near confluence, at ca. 500 m elevation, of Rfo Bonito and a large quebrada flowing from the SW), 15?38'N 86052'W, 1900 m, 23 Apr. 1996 (fl & fr), R. J. Evans 2553 (holotype, CAS; isotypes, EAP, MEXU, MO). Figure 1. Frutex humifusus, ramuli quadrangulati demum rotundato-quadrangulati sicut petioli foliorum venae primariae subtus hypanthiaque densiuscule setosi pills plerumque 0.5-1 mm longis laevibus pro parte glanduliferis. Lamina 1.4-2.9 x 0.9-1.9 cm elliptica vel ovato-elliptica, penninervis, supra dense strigosa pilis laevibus 0.5-1 mm longis persistentibus, subtus dense strigosa pilis laevibus 0.5-1 mm longis. Flores 4-meri in axillis foliosis superioribus solitarii, pedicellis 1.6-2.6 cm longis. Stamina dimorphica; filamenta 7 mm vel 5 mm longa. Stamina maiora: thecae 4.5-5 x 0.5-0.75 mm; connectivum 2 mm prolongatum ad basim glandulis 0.25-0.5 mm stipitatis ca. 2 ornatum. Stamina minora: thecae 3 x 0.5 mm; connectivum ca. 0.1 mm prolongatum. Ovarium 4-loculare; semina 0.5 mm longa. Low, procumbent, perennial subshrub with trailing branches to 1 m long and upright leafy axillary branchlets typically less than 8-9 cm in length. The quadrate to rounded-quadrate cauline internodes densely hirsute with spreading, smooth, brown hairs 0.5-1 mm long. Leaves of a pair essentially equal in size; petioles 3-12 mm long, densely hirsute like the NovoN 9: 127-130. 1999. This content downloaded from 157.55.39.35 on Fri, 02 Sep 2016 05:44:08 UTC All use subject to http://about.jstor.org/terms