Thamnobryum proboscideum H. Robinson 1974

Thamnobryum proboscideum

Thamnobryum proboscideum (Broth.) H. Robinson, Phytologia 29(2):118, 1974.

Thamnium proboscideum Broth. in Skottsb., Nat. Hist. Juan Fernandez 2:433, 1924. [Original material: Pangal, 205 m, Mas a Tierra, coll. C. & I. Skottsberg n. 256.]

Rather large plants with secondary stems to 7 cm long, stipitate for about 3 cm below, rather pinnately to subbipinnately branched above. Branches to 3 cm long. Stipe covered with scalelike leaves. Main stem and branch leaves erect-spreading, ca. 2 mm long, lanceolate, rather concave; apices usually excised, sometimes minutely serrulate; costae stout throughout, 80–100 μm wide below, excurrent in a stout, rough point, smooth abaxially; cells of lamina near apex oval or triangular, irregular, median cells mostly oblong hexagonal, cells longer toward base, at base linear. Dioicous. Sporophyte unknown.

The species is endemic to Mas a Tierra. No material has been seen in this study, but both Brotherus (1924) and Bartram (1957) emphasize the long-excurrent costa of the leaves.