Monographs Details: Fissidens filiformis Z.Iwats.
Authority: Buck, William R. 1987. Bryostephane Steereana: A Collection of Bryological Papers Presented to William Campbell Steere On The Occasion of His 80th Birthday. Mem. New York Bot. Gard. 45: 1-749.
Family:Fissidentaceae
Description:Latin Diagnosis - Planta minuta; cauHs filiformis, 20-30 mm longus, cum folris 0.62-0.87 mm latus; folia 50-70-juga, ovata, 0.35-0.60 mm longa, 0.15-0.22 mm lata, apice late acuta; lamina vera ad 2/3 folium producta, marginibus elimbatis; costa percurrens; cellulae laminates 5.0-7.5 µm longae, pluripapillosae.

Species Description - Plants threadlike, yellowish green to yellowish brown in herbarium specimens; stems simple, very rarely branched, mostly 20-30 mm long, 0.62-0.87 mm wide with leaves; central strand lacking, cortical stem cells smaU and thick-walled; axillary hyaline nodules not diflferentiated; rhizoids on stems, macronemata prominent from axils of leaves, micronemata on stem surface usually below leaf bases and thinner than macronemata; stems laxly foliate, leaves 50-70 pairs on mature stems, not overlapping; upper leaves ovate, 0.35-0.60 mm long, 0.15-0.22 mm wide, apex widely acute, base of dorsal lamina round, not decurrent; vaginant laminae about 2/3 of leaf length; margin minutely crenulate throughout, not bordered; costa percurrent, some cells at upper end of costa prolate; laminae in 1 cell layer in cross-sections; cells of apical lamina quadrate to irregularly hexagonal, thin walled, 5.0-7.5 µm long, obscure, mostly with 4 minute papillae on each laminal cell. Dioicous? No sexual organs were found.

Discussion:

Fig. 1.

The present new species is characterized by (1) threadlike stems with 50-70 pairs of small ovate leaves, (2) obscure laminal cells with usually 4 minute papillae, (3) lack of leaf borders, and (4) dioicous? inflorescences. The habitat ofthe present species is not known. However, elongate stems suggest that the plants grow in wet habitats, but no diatoms were found on the plants. The obscure laminal cells with 4 minute papillae per cell suggest that the plant might be related to F. ceylonensis Dozy et Molk. and its allies, but limbidia of leaves are not found in the present new species. As described by Iwatsuki and Mohamed (1987), F. ceylonensis has limbidia on vaginant laminae (often intralaminar), and has autoicous inflorescences. Since the Thailand collections are such strange plants with such distinct gametophytic characters from other species, I have proposed it as a new species. Iwatsuki and Suzuki (1982) pointed out that some young plants of F. microcladus Thwait. et Mitt, and F. obscurirete Broth, et Par. often have leaves without borders. This fact may suggest that the present new species is related to the species of sect. Semilimbidium.