Pylaisia camurifolia (Mitt.) A. Jaeger, Ber. Thätigk. St. Gallischen Naturwiss. Ges.

Ignatova, E. A., Kuznetsova, O. I., Shafigullina, N. R., Fedosov, V. E. & Ignatov, M. S., 2020, The genus Pylaisia (Pylaisiaceae, Bryophyta) in Russia, Arctoa 29 (1), pp. 135-178 : 160-163

6. Pylaisia camurifolia (Mitt.) A. Jaeger, Ber. Thätigk. St. Gallischen Naturwiss. Ges. : 307 (Gen. Sp. Musc. 2: 373). 1878. — Stereodon camurifolius Mitt., J. Proc. Linn. Soc., Bot., Suppl. 1: 96. 1859.

Figs. 19 , 20 , 34G .

Note on the taxonomy: Pylaisia camurifolia was placed in the synonymy of P. falcata by Arikawa (2004), and in our previous publications ( Bakalin et al., 2009;

Cherdantseva et al., 2018) we reported it under that name. However, sequence data show a considerable genetic distance between P. falcata from Mexico (where from it has been originally described) and specimens from Asian Russia. In addition, plants referred to P. falcata from Asian Russia are somewhat smaller and also differ in smaller size of spores, ca. 20 µm only, while P. falcata is described as having spores 25–40 µm by Arikawa (2004), although Sharp et al. (1994) reported spores 20–40 µm, and Allen (2018) described them as16–30 µm. The protologue of Pylaisia camurifolia , which was described from Nepal, does not mention spore size; however, Stereodon microsporus Broth. , described from China and subsequently synonymized with Pylaisia falcata ( Ando, 1978) , was described as having small spores, 20–25 µm, i.e., quite similar to ‘ P. falcata ’ from the Russian Far East.

Considering the fact that Pylaisia camurifolia is the eariest name of Pylaisia falcata -group described from Asia, and also that the type of Stereodon microsporus from Yunnan (BM001108723, with available high resolution scan) is habitually similar to plants from Russia, and also that according to Brotherus (1925) its spores are 20–25 µm, we use the name Pylaisia camurifolia for ‘Asian P. falcata ’ instead of just retaining P. falcata . The further study with the additional sequencing of South- West Chinese and Himalayan specimens is obviously required for complete and correct naming of P. falcata s.l. plants in Asia.

Description. Plants medium-sized to moderately large. Stems and branches curved, loosely foliate; leaves homomallous to falcate-secund, turned outwards substrate. Stem leaves 1.2–1.7× 0.5–0.6 mm, ovate to ovate-lanceolate, rather gradually narrowed into a long acumen, conspicuously and abruptly rounded to insertion; margins subentire; median laminal cells 30–55×5–6 µm, alar cells subquadrate, form a compact groups in basal leaf angles, alar groups quadrate or transverse rectangular, ca. 7 cells long and 7 cells wide. Branch leaves somewhat smaller. Inner perichaetial leaves erect to reflexed, not much elongated after fertilization. Capsules cylindrical. Peristome forming low conus when dry. Exostome teeth 230–260 µm long above the mouth, dorsal plates smooth below, papillose above; endostome up to 300 µm above the mouth, adherent to exostome only at base; segments rather broad, split only in lower 1/3 along the line that continues the segment keels; endostome moderately papillose. Spores 19–22 µm.

Differentiation. This species is unlikely to be mistaken with other species of Pylaisia known from Russia. It is a large plant, yellow-green with some reddish or orangish tint, with strongly falcate, rather loosely arranged leaves. Leaves have a triangular basal portion, are abruptly rounded to the insertion and have compact alar groups that are as broad as long. Peristomes are characterized by free upper parts of endostome segments which are broad and keeled. However, lower part of the endostome basal membrane is adherent to exostome teeth, resulting in splits of endostome in proximal part along the lines that are a continuations of the segment keels ( Fig. 20 ).

Distribution. It seems that this species is rare in Asia. Only two collections, from Sakhalin and Kuril Islands, were found in Russia (see sequenced samples, Table 1).

Figures

Fig. 19. Pylaisia camurifolia (1–10: Ca1, OK209, Russia, Kuril Islands; 11–15, Ca2, OK210, Sakhalin) and P. falcata (16– 22: F1, OK546, Mexico). 1, 3: habit, dry; 2, 21: median laminal cells; 4, 6–7, 11–13, 16–17: stem leaves; 5, 20: upper laminal cells; 8–9, 14–15, 18–19: branch leaves; 10, 22: basal laminal cells. Scale bars: 5 mm for 3; 2 mm for 1; 1 mm for 4, 6–9, 11–19; 100 µm for 2, 5, 10, 20–22.

Fig. 20. Pylaisia camurifolia, Ca1, perisome under light micro- scope, showing endostome split near base along the continuation of the segmens keels due to its partial adherence to exostome teeth, but with mostly free broad and keeled segments. Scale bars: 100 µm for A; 50 µm for B.

Fig. 34. Habit of the Russian species of the genus Pylaisia. A: P. bezgodovii, OK212; B: P. steerei, OK212; C: P. curviramea, Irkutsk, OK2682; D: P. polyantha, Moscow, P10; E: P. polyantha, haplotype‘orientalis’, Altai, OK2729; F: P. coreana, Yakutia, OK2722; G: P. camurifolia, Kurils, OK209; H: P. condensata, OK446; I: P. brotheri, OK2799; J: P. subcircinata, OK830; K: P. stereodontoides, OK2811; L: P. obtusa, OK226. Scale bar: 1 mm for all.