A New Species of Breutelia (Bartramiaceae) from Central America, with a Key to the Species of Breutelia in Central America

Abstract

Breutelia pilifera differs from all other species of Breutelia by its non-sheathing leaves that have costae excurrent into long, naked awns and reddish orange basal leaf cells across the leaf insertion. A key to the 14 species of Breutelia in Central America is given. Breutelia is a robust genus found mostly at high elevations in the Neotropics. The genus has some distinctive, easy to recognize species, but most are taxonomically difficult. Two characters of critical taxonomic importance are leaf stance and the degree or type of alar region differentiation. Unfortunately, proper character-state evaluation of these features often requires previous familiarity with the genus. There are two basic leaf stances: spreading from the insertion and sheathing at the base. This leaf stance distinction is used in the beginning of many keys to the species of Breutelia (Bartram, 1949; Griffin, 1994; Churchill & Linares, 1995). It works tolerably well, but for some species it is difficult to evaluate because the two forms grade into one another and sometimes both can be found within single collections. Likewise, the degree or type of alar region differentiation, which often involves subtle distinctions, can be difficult to evaluate because of variation both within and among collections. Proper evaluation of this last feature requires the examination of many leaves. Breutelia has an odd endostome structure that helps to bind the Bartramiaceae together. In those members of the family with a well-developed endostome the segments are broad and when examined with a hand lens appear to be positioned opposite to rather than alternating with the exostome teeth. Closer examination reveals each segment is split along the median line nearly to the basal membrane, and each half segment diverges outward toward the where it often meets the diverging half segment of the next segment over, thus framing the (see Fig. 1B). This endostome strucuture is sometimes inaccurately noted in the literature as cilia cohering (Zales, 1973); however, Shaw and Rohrer (1984) correctly evaluated the structure. Within the Bartramiaceae this type of endostome is found in Bartramia, Breutelia, Philonotis, and Plagiopus. Curiously, similar endostomial modification is found in the Bryaceae (Acidodontium and Brachymenium columbicum (De Notaris) BrotherUS). Breutelia is closely related to Philonotis, and although the two genera are generally easy to distinguish due to the larger size of Breutelia, technically they are difficult to separate. Sporophytically, the genera are identical; gametophytically, only the larger size, generally narrower and longer leaf cells, consistently plicate leaf bases, and differentiated alar cells of Breutelia separate the two genera. However, Philonotis approximates Breutelia in all of these features; even their size distinction is