Brachymenium elimbatum Canestraro & D.F. Peralta, 2020

Canestraro, Bianca Kalinowski & Peralta, Denilson Fernandes, 2020, New and endemic species of Brachymenium (Bryaceae, Bryophyta) in the Atlantic Rainforest of Brazil, Phytotaxa 446 (4), pp. 220-228 : 224-225

Brachymenium elimbatum Canestraro & D.F. Peralta , sp. nov.

Type:— BRAZIL. Rio Grande do Sul: Caxias do Sul, Campus da UCS, sobre tronco de árvore, elev. 780 m, 1 September 2009, R.C. Molon s.n. (holotype SP418931!, isotype HUCS35758 photo!).

Figures 1 and 3B .

Diagnosis: — Plants medium-sized. Leaves appressed and spirally contorted when dry, lanceolate to oblong, apex ending in a short to long arista, margins not bordered, plane, entire; costa tapering above, sub-percurrent. Capsules erect, oblong. Basal membrane of endostome to half of the exostome teeth length, segments and cilia absent.

Plants medium-sized, light green, in dense tufts; stems 0.7–1.8 cm long, simple or branched, central strand present; rhizoids dense at base. Leaves appressed and spirally contorted when dry, spreading when wet, 0.1–0.2 cm long, lanceolate to oblong, apex long-acuminate ending in a short to long arista, margins not bordered, plane, entire; upper cells hexagonal to rhomboidal, 26–42 × 13–21 µm, basal cells rectangular to sub-quadrate, 18–44 × 11–19 µm; stereids present; costa tapering above, sub-percurrent, green, space between the end of the costa and arista with more than five cells. Perichaetial leaves differentiated, 0.1 cm long, triangular-lanceolate, costa short to long-excurrent. Dioicous. Setae 1.5 cm long. Capsules 0.3 cm long, erect, oblong. Operculum 0.01 cm long, conic, short-apiculate. Exostome teeth triangular, papillose, orange, closely spaced; endostome papillose, hyaline, basal membrane to half of the exostome teeth length, segments and cilia absent. Spores spherical, lightly roughened, 18–31 µm.

Paratypes:— BRAZIL. Paraná: Morretes , 25 July 2014, leg. Peralta, D.F. 16415 (SP!) . Rio Grande do Sul: Caxias do Sul , 17 January 2006, leg. Bordin, J. 299 (HUCS!, SP!) ; loc. cit., 12 November 2005, leg. Bordin, J. 163 (HUCS!, SP!) ; loc. cit., 6 October 2006, leg. Yano, O. 29271 (SP!) ; São Marcos , 27 April 1983, leg. Yano, O. 7056 (SP!) .

Distribution and ecology: —Endemic to Brazil, found in the states of Paraná and Rio Grande do Sul ( Fig. 3A–B ). Corticolous and exclusive to the subtropical portion of the Atlantic Rainforest.

Etymology: —The specific epithet is a reference to the unbordered leaf margin.

Notes: — Brachymenium elimbatum is characterized by leaves with sub-percurrent costa, with plane and unbordered margins and by the lanceolate to oblong capsules ( Fig. 1 ). It is close to B. hornschuchianum , however the latter leaf margins are reflexed and bordered by two rows of narrow cells and the leaves are oblong, lanceolate to elliptic ( Ochi 1980). Since the holotype did not cite the coordinates, we have estimated them as 29°09’07’’S, 51°08’59’’W.

Brachymenium elimbatum resembles Bryum brachymenioides (Dixon & P. de la Varde 1930: 177) Ochi (1971: 66) , an Asian species ( Ochi 1985). Both have sub-percurrent costa and oblong to lanceolate leaves, however the latter lacks the arista and the upper leaf cells are elongate with thick walls.

Brachymenium elimbatum is similar to B. pulchellum Hornsch. (1840: 36) . According to the original description ( Hornschuch 1840), B. pulchellum has channeled and concave leaves, involute leaf margin and reddish costa (vs. plane leaves and margins, green and concolorous costa in B. elimbatum ). Although Ochi’s (1980) effort to locate the type specimens in his monograph, he have not seen the type of Brachymenium pulchellum , therefore he did not assume a taxonomic decision for this name. The type material of B. pulchellum is not indicated in the publication ( Hornschuch 1840) and, thus we could not locate it neither (G herbarium and JStor Global Plants 2019). According to Crosby et al. (1999), the name Brachymenium pulchellum is insufficiently known and the only information are in the Index Muscorum and in the original publication from Hornschuch. Additionally, the geographical distribution of Brachymenium pulchellum (Minas Gerais – Tropical Forest) and B. elimbatum (Rio Grande do Sul and Paraná – subtropical Araucaria Forest) do not match. Ochi (1980) mentioned that B. pulchellum is similar to B. hornschuchianum , however his comment is questionable considering that he did not analyzed the type of B. pulchellum and some samples named as B. pulchellum were changed to B. hornschuchianum by Ochi.

Considering Ochi’s infrageneric classification (1992), B. elimbatum can be positioned in the section Brachymenium Ochi (1992: 232) by medium-sized plants in dense tufts, capsules erect oblong-pyriform with a short and slender neck, short-conic operculum, spores medium sized (up to 40 µm).

Figures

FIGURE 1. Brachymenium elimbatum: A. Habit, wet. B. Vegetative leaf apex. C. Vegetative leaf base. D–E. Vegetative leaves. F. Perichaetial leaf. G. Cross section of the leaf. H. Cross section of the stem. I. Capsule and operculum. J. Exostome teeth and endostome membrane. K. Spores. (Molon s.n. SP418931).

FIGURE 3. Distribution of the new species of Brachymenium in Brazil. A. The Atlantic Rainforest of Brazil in gray and detailed area in black square. B. Brachymenium elimbatum. C. Brachymenium sublineare.