A New Species of Fissidens from the Southern Appalachian Mountains

Abstract

Fissidens appalachensis sp. nov. is described from North Carolina and Tennessee. It is the only representative of the section Pachylomidium known for North America north of Mexico. Fissidens (Sect. Pachylomidium) appalachensis sp. nov. (Fig. 1-8) Plantae submersae, sat robustae, 0.5-1.5 cm longae; caules simplices vel furcati; folia in jugis 6-12, patentia, ligulata vel oblongo-lanceolata, acuta, plerumque mucronata, 0.4-0.7 mm lata et 2-3 mm longa, apice integres vel serrulata, limbo cartilagineo; costa subpercurrens; cellulae hexagonae, ll-15/L, non crassae. Dioicae vel raro synoicae. Perigonia et perichaetia terminalia, seta 4-4.5 mm longa; capsula juvenis, ovata, symmetrica, erecta, ca. 1.3 mm longa, operculum conicum vel breviter rostratum. Plants submerged, decumbent, in fan-shaped clumps, moderately robust, dark green to blackish below, stems mostly 0.5-1.5 cm long, simple to sparingly branched; leaves in 6-12 pairs, scarcely overlapping, erect-spreading and slightly contorted when dry, ligulate to oblong-lanceolate, acute, often mucronate, usually 0.4-0.7 x 2-3 mm, vaginant lamina 1/2 length upper leaves to % length lower leaves, margins entire to sometimes serrulate near apex, with a border of 1-7 rows of thick-walled, elongate cells, several layers in thickness and nearly circular in cross section, extending nearly to the leaf base and ending 1-7 cells below the apex or disappearing in the mucro; costa subpercurrent, often ending in the mucro; cells of the lamina monostratose, or seldom bistratose in places, smooth, hexagonal, 11-15, in diameter, thin-walled; 1 thank Drs. L. E. Anderson, R. A. Pursell, and H. E. Robinson, whom I consulted regarding taxonomic problems in Fissidens. Miss Shirley Watkins made the figures. This research was aided by Grant GB-2495 from the National Science Foundation to Highlands Biological Station. 2 Department of Botany, Duke University, Durham, North Carolina 27706. This content downloaded from 40.77.167.151 on Wed, 17 May 2017 17:54:34 UTC All use subject to http://about.jstor.org/terms 1969] ZANDER: A NEW SPECIES OF FISSIDENS 407