6. PSEUDOSYMBLEPHARIS            Plate 7.

Pseudosymblepharis Broth., Nat. Pfl. ed. 2, 10: 261, 1924. Lectotype: Pseudosymblepharis papillosula Card. & Thér. fide Saito, J. Hattori Bot. Lab. 39: 439, 1975.

            A genus found in most tropical and warm-temperate areas, occurring on soil, rock (mostly calcareous) and bark.

            This genus is like both Tortella and Trichostomum subg. Oxystegus in the plane or broadly incurved leaf margins (Pl. 7, f. 20) and well differentiated, often inflated basal cells that usually extend up the margins in a more or less distinct vee (Pl. 7, f. 9, 18). The broadly sheathing leaf base with distinct “shoulders” has been used in the past as a major character, but is actually found to some extent in other genera, and is poorly or not at all developed in some species of Pseudosymblepharis. An additional and possibly better character is the relative size of the ventral stereid band (Pl. 7, f. 6, 20). In Pseudosymblepharis the ventral stereid band is almost always distinctly larger than the dorsal, and is often strongly bulging ventrally. Tortella may be additionally distinguished by the usually better developed peristome, while Trichostomum subg. Oxystegus differs, gametophytically, by the vee of basal cells poorly developed or absent. There may well prove to be no acceptable distinction between Pseudosymblepharis and Trichostomum subg. Oxystegus, excepting the color of the peristomes, yellow to white in the former and red in the latter (also see discussion of Norris and Koponen 1989). In leaf shape, P. indica might be recognized in Trichostomum subg. Oxystegus (cf. Hilpert 1933) but the costa is quite thick, with the ventral stereid band larger than the dorsal (at least in the larger, mature leaves). Problematically, T. (Oxystegus) hybernicus has the sheathing leaf base of Pseudosymblepharis and a ventral stereid band equal to or greater than the dorsal, but the rectangular upper laminal cells and thin-walled cells of the central cylinder associate it clearly with Trichostomum tenuirostris. The genus Pseudosymblepharis has considerable resemblance to Symblepharis Mont. (Dicranaceae), but gametophytes of the latter genus may be distinguished by their smooth leaf cells. The generitype of Trichostomum, T. brachydontium, has the ventral stereid band much larger than the dorsal in most very robust specimens, much as is the case in Pseudosymblepharis. Weissia jamaicensis has a leaf shape and costal structure similar to that of Pseudosymblepharis but the sharply and narrowly incurved upper laminal margins are characteristic only of Weissia s. lat. and Chionoloma. This entire relationship needs careful revision.

            Tortella has 32 filamentous teeth, longer than 500 µm, these strongly twisted. Trichostomum (including subgenus Oxystegus) has 16 teeth cleft variously to near that base, shorter than 400 µm, and straight to very weakly twisted. Future evaluation may find that Tortella and Trichostomum (s. lat.) may better be divided by characters other than those of the sporophyte and basal cell area shape of the leaves. A similar situation has occurred in the Barbula-Didymodon group, which was in the past distinguished along similar lines of peristome morphology, but which is now (Saito 1975a) separated into three genera (Bryoerythrophyllum being segregated from Didymodon) by a combination of several gametophytic characters (see treatments below).

            There may be quite a difference in stature between various collections of the same species, with certain variation correlated with plant size. In P. schimperiana, for instance, small plants may be only weakly sheathing at the leaf base, the hyaline basal cells of such collections may reach up the margins to half the length of the leaf, and the leaves are more commonly fragile. Examined collections of the widespread species Old World species P. angustata (holotype, NY!) are nearly identical to the New World P. schimperiana, but differ in lacking a stem central strand (weak in P. schimperiana). A revision of this genus, however, may yet demonstrate synonymy and a pan-tropical distribution of P. angustata.