Calyptothecium acostatum J.X. Luo

Calyptothecium acostatum J.X. Luo View in CoL (Fig. 3)

Specimens examined: Bhutan. Wangdue Phodrang, N of Kothoka, Quercus glauca forest with Pinus wallichiana and Tsuga emergents, little grazed, on mountain spur, 27°22’N 89°57’E, 2520 m a.s.l., 8.X.1998, G. & S. Miehe 98-384-20 (H); same coordinates, little disturbed Quercus lanata - Quercus griffithii forest on S-facing slope, 9.X.1998, G. & S. Miehe 98-385-27 (H). Tashigang, Tashiyangtse, Dong La E side, evergreen Quercus forest with emergent Pinus bhutanica trees on SE-facing slope, little grazed, 27°25’ N 91°24’ E, 2540 m a.s.l., beard mosses (lower branches), 30.V.2000, G. & S. Miehe 00-63-39 (H).

Calyptothecium acostatum was described from eastern Xizang (Luo, 1983), but collections obtained since 2005 extend its distribution southward to the Gaoligongshan portion of the Hengduan Mountains in NW Yunnan (https://www.tropicos.org/name/35112411). The species is easily distinguished by the very large basal auricles in the leaves, and by the very weak or (mostly) absent costa ( Yu & He, 2011). The Xizang type material was collected on tree trunks at 2300–2400 m a.s.l., and the Yunnan material ranges between 1900 and 2400 m a.s.l. The Bhutan specimens reported here occur between 2410 and 2540 m a.s.l. Two of the specimens lack information on the substrate, but one is described as “beard mosses (lower branches)”.

Illustrations: Lou 1983: p. 225, figs. 10–12; Yu & He, 2011: p. 218, pl. 336, figs. 1–3.