62. TORTULA               Plates 84, 85, 86, 87, 88, – 89.

Tortula Hedw., Sp. Musc. 122, 1801, nom. cons. non Roxburgh, 1800. Lectotype: Tortula subulata Hedw.

Beccaria C. Müll., Nuov. Giorn. Bot. Ital. 4: 11, 1872.

Bauriella Warnst., Hedwigia 57: 88, 1915, nom. inval. prov. Type: Tortula polyseta (C. Müll.) Warnst.

Tortula sect.? Piliferae De Not., Mem. R. Acc. Sc. Torino 40: 287, 1838, rank not indicated; inoperative in piority I.C.B.N. Art. 35.2.

Barbula sect. Amphidiopsis C. Müll., Linnaea 42: 332, 1879. Type: Barbula amphidiifolia C. Müll.

Barbula sect. Pilifera Lzaro é Ibiza, Bot. Descr. Comp. Fl. Esp. 1: 586, 1896.

Barbula sect. Orthopodiae Kindb., Eur. N. Amer. Bryin. 2: 245, 1897.

Barbula sect. Catillaria C. Müll., Gen. Musc. Fr. 425, 1900. Type: Barbula pellata Schimp.

Pottia sect. Beccaria (C. Müll.) C. Müll., Gen. Musc. Fr. 389, 1900.

Pottia subsect. Acutae C. Jens., Skand. Bladmfl. 203, 1939, nom. inval. descr. suec.

See sectional synonymy for additional nomenclature.

            Found on most continents in various habitats, mainly soil.

            With the segregation of various genera (Zander 1989: Chenia, Dolotortula, Hennediella, Hilpertia, Sagenotortula, Stonea, Syntrichia), Tortula becomes a fairly homogeneous group with very similar gametophytes and a characteristic tendency to reduction in the sporophyte. Thus, the correlations of season of sporophyte maturation (Zander 1979d) with genus (Pottia having spring and winter sporophyte maturation dates and Tortula in the traditional sense having dates mainly in the spring and summer) is probably a reflection of “life strategy” (cf. During 1979) rather than phylogeny, though this needs to be tested. Major characters of Tortula as presented here include presence of stem central strand (rarely absent or present in different stems of same collection, e.g. T. brevissima) and absence of sclerodermis and hyalodermis (Pl. 84, f. 2, 17); leaves usually obovate to spathulate, margins usually narrowly recurved below and entire; costal stereid band usually semicircular to rounded in section, hydroid strand present, dorsal epidermis usually present (Pl. 84, f. 7, 8, 21); upper laminal cells usually rather large and clear (i.e. walls usually relatively unobscured by the papillae, Pl. 84, f. 9); propagula absent; upper laminal KOH reaction usually yellow.

            Tortula is distinguishable from Syntrichia by the semicircular to rounded stereid band (not crescent-shaped) and yellow KOH reaction of the upper laminal cells (not red). Unlike Syntrichia, a dorsal costal epidermis is usually differentiated, either completely or occasionally only laterally (Pl. 89, f. 15—as is also the case in Hennediella). The yellow KOH reaction is usually present, but some few taxa have no color reaction (e.g. T. entosthodontacea), or the basal cells may be brick red (e.g. T. raucopapillosa), or the leaves may blush red medially in the upper part of the leaf (e.g. T. atrovirens), or the older leaves may be red and the younger yellow (e.g. T. lingulata), or all leaves may have a reddish orange cast (e.g. T. nevadensis). But the characters of these taxa otherwise are those of Tortula as here emended. Hennediella is distinguished by its red KOH reaction, commonly dentate or serrate and plane upper laminal margins, and superficially flattened upper laminal cells. Papillae may be absent in some Tortula species or variously expressed in different specimens of the same species.

            Chamberlain (1978) recognized Pottia caespitosa, but the leaves have plane margins, the upper laminal cells are rather small and thick-walled, and costal sections show two stereid bands. This small-statured species is actually a Trichostomum (as witness the combination Trichostomum caespitosum (Bruch ex Brid.) Jur.), differing somewhat from other species of that genus by the broadly sheathing perichaetial leaves and quite neckless capsule.

            Upon examination of the sporophytes of a considerable range of species of Pottieae, there was found to be no sharp difference between traditional “Tortula” peristomes with 32 similar rami (Pl. 84, f. 12–13) and “Desmatodon” peristomes with 16 teeth cleft to near the base or to a basal membrane (i.e., 32 paired rami, Pl. 86, f. 16; 87, f. 9–10). Even if some difference was statistically demonstrable, it would cut across observed (and as taxonomically recognized here) clearly defined generic groupings based on several gametophytic characters. It is simpler to entertain convergence of one character (short, probably reduced peristomes having teeth paired) than convergent evolution of several distinctive gametophyte morphotypes two or more times. The flattened basal portion of “Desmatodon” peristome teeth may be explained as a cleft portion of the basal membrane. The proximally flat teeth of Desmatodon species are also different from the almost terete filaments of Tortula with long, twisted peristomes simply because the long filaments of Tortula have distal regions little wider than their thickness. A cladistic evaluation at the species level may clarify this.

            Visotska's (1967) proposal of a subfamily Tortuloideae (no type cited), based on a chromosome number of 12 and intended to contain Tortula, Aloina and Crossidium, was criticized on cytological grounds by Nyholm and Wigh (1973) because several species of Tortula have a basic chromosome number of x = 13. Evaluation of chromosome counts given by Fritsch (1982, 1991) gave both 12 and 13 as basic numbers for both Tortula s. str. and Syntrichia as conceived in the present study; however, Newton (1972) found 7 for S. robusta and Ramsay (1974) found n = 6+m for S. papillosa.

            An electron microscopical study by Lewinsky (1974) of spore ornamentation in 10 European species of Tortula s. lat. showed differences between the spores of the specimens studied (only one or two collections were examined for each species although 20–30 spores from two to five capsules were studied in each species), which probably represent differences between the species, but she found no evidence of differences between traditional sections of the genus.

            Mishler's (1986a) cladogram of postulated phylogenetic relationships of several species of Tortula s. lat. recognized Tortula s. str. (as recognized here) as a primitive group (he listed T. subulata, T. mucronifolia and T. muralis) distinct from several other species (all recognized here as Syntrichia) by the upper laminal cells not strongly mammilose.

            Corley et al. (1981) gave an up-to-date presentation of the sections of the genus as represented in Europe. Their apprehension of Desmatodon as a rather small assemblage of the type species and closely related taxa presages the present study. They stated that Desmatodon “is not defined by sound technical characters, and there has been much confusion about which species should be assigned to it. As with Didymodon there has been too much emphasis placed on the peristome, which is not a conservative character in Pottiaceae.”

            Tortula muralis, T. leucostoma and T. altipes occasionally have a small ventral (sub)stereid band (Pl. 85, f. 3). The costa is, however, rounded in section and generally unlike that of Barbula.