Cynodontium caucasicum Ignatova & Fedosov, 2024

Ignatova, E. A., Czernyadjeva, I. V. & Fedosov, V. E., 2024, A new species of Cynodontium (Rhabdoweisiaceae, Bryophyta) from Russia with comments on related species, Arctoa 33 (1), pp. 24-30 : 28-30

Cynodontium caucasicum Ignatova & Fedosov , species nova. Fig. 2

Type : Russia, Caucasis , Charodinsky District , near Zajach’i gates, Fedosov 13-1-193, MW9111628 (Holotype MW, isotype MHA) .

Diagnosis. Similar to Cynodontium gracilescens (F. Weber & D. Mohr) Schimp. in having high, spinulose mammillae/papillae in each cell on both adaxial and abaxial leaf surface, and unistratose leaf laminae including leaf margins, but differs from it in having straight versus arcuate setae when wet, and narrowly acute versus often subobtuse leaf apices.

Etymology: The name refers to the region where the most specimens of the species originate from.

Plants in loose tufts, yellowish-green or light green, dull. Stems 2–5(–8) cm. Leaves crisped when dry, widely spreading to arcuate-recurved when wet, (1.9–)2.5– 3.4(–4.3)×(0.35–)0.5–0.6(–0.7) mm, narrow lanceolate, narrowly acute or acuminate at apex; margins recurved in lower 1/2 on one or both sides, plane distally, crenulate due to high mammillae; costa percurrent or ending few cells below leaf apex, strongly mammillose on dorsal surface in the upper 1/3; leaf lamina unistratose; cells in upper and median leaf portion transverse-rectangular, quadrate and short rectangular, 7–10(–12) µm wide, on both surfaces sharply mammilose-papillose, opaque; in lower part of leaf elongate rectangular, (35–)50–85(–120) µm long, smooth, becoming shorter towards leaf margins. Autoicous. Sporophytes frequent. Perichaetial leaves from semi-sheathing bases gradually narrowed into long acumina, mammilose-papillose in distal portion; perigonial leaves acuminate. Setae 0.5–0.9(–1.2) cm, straight when dry and wet, yellow or brownish. Capsules erect or slightly inclined, straight, 0.9–1.8 mm long, ovate, symmetrical, not strumose, furrowed when mature, constrict- ed below mouth after spore release, yellowish to brownish. Peristome well-developed, teeth split to 1/2 of their length or lower into 2(3) unequal prongs, reddish, often lighter at tips, papillose and vertically striolate. Opercula with long oblique beaks. Annuli persistent, formed of one row of small cells. Spores 17–25 µm, brownish, finely papillose.

Differentiation. Separating Cynodontium caucasicum from C. gracilescens is not easy. Their distinctions include straight vs. arcuate setae and usually acute vs. subobtuse leaf apices. We managed to study only few old specimens of C. gracilescens , and in all of them capsules were elevated high above the tuft on thin, yellow setae 10–14 mm long, geniculate when dry and cygneous when moist. Plants of C. caucasicum in most specimens had slightly shorter (usually 6–8 mm long) and stouter setae, usually straight but occasionally curved when moist but never geniculate when dry. However, according to the descriptions of C. gracilescens in Europe- an floras, it has setae of the same length as in C. caucasicum ( Limpricht, 1890) , or even shorter, 5.5–8.5 mm, apparently based on specimens from the Iberian Peninsula ( Heras & Infante, 2015). It can be, however, caused by presence of C. caucasicum in Europe, which has not been distinguished from C. gracilescens before the molecular evidence appeared. Note that Heras & Infante (2015) describe the seta of C. gracilescens as ‘recta a ligeramente flexuosa’ (straight to slightly flexuose) but not cygneous. We also tentatively refer to C. caucasicum one specimen without exact data on locality, collected by D. H. Hoppe and C. F. Hornschuch ‘in alpibus’ (apparently in Europe). It has setae 5 mm long, totally straight.

An additional character which can be helpful for separating C. caucasicum and C. gracilescens is the shape of perichaetial leaves: they are gradually tapered into long acumina in the former species and abruptly constricted into short apiculi in the latter one (see Fig. 1 G & H vs. A & B). However, only a restricted number of C. gracilescens specimens were available for our study, so we suggest the use of this character with caution.

There is also a great resemblance between C. caucasicum and C. serrulatum (Funck ex Brid.) Lindb. (= Oreoweisia torquescens ) in having unistratose leaf laminae, densely mammilose-papillose on both surfaces, but leaves of O. torquesens are more widely acute, and its capsules are smooth, with shorter, more slender and not divided peristome teeth; this species is also unknown in Russia.

Distribution and ecology: Cynodontium caucasicum is currently known in Russia only from the Caucasus (Republics Karachayevo-Circassian, Kabardino-Balkarian, North Ossetia – Alania, and Dagestan), it was also collected in Georgia ( South Ossetia). Few old herbarium specimens from Central Europe were also observed; however, distribution of this species in Europe outside Russia and neighboring countries of the Caucasus needs to be clarified. In the Caucasus, it grows in altitudinal range ca. 1850–2400 m, in pine and birch forests in niches un- der and between rocks, on vertical and overhanging rock surfaces, on rotten logs, tree bases and exposed roots.

Cynodontium asperifolium occurs in Russia mainly in its Asian part and Urals, but it was also found in one locality in Karachaevo-Circassian Republic, Teberda Nature Park. The identity of the Caucasian specimen was confirmed by molecular data (specimen RF 77 in Fedosov et al., 2021).

Distribution of C. caucasicum and C. asperifolium in Russia is mapped in Fig. 4 .

Other studied specimens: Cynodontium caucasicum . CAUCASUS. RUSSIA: Karachayevo-Circassian Republic: Teberda Nature Reserve: Oriuchat Creek valley ( Nazlykol River tributary), Ignatova 07-73 ( MW9030220 ) ; Oriuchat Creek valley ( Nazlykol River tributary), Ignatova 07-73 ( MW9030220 ) ; right slope of Ullu-Murudzhu River valley, Ignatov & Ignatova 05-3935 ( MW9030227 ) ; same place, Ignatov & Ignatova 05-3809 ( MW9030228 ) ; same place, 9.VIII.1986, Ignatova s.n. ( MHA9013705 ) ; Goralykol River valley , Ignatova 07-126 ( MW9030219 ) ; Kyshkadzher River valley , 14.VIII.1986, Ignatova s.n. ( MHA9013706 ) ; Azgek River valley, left bank at confluence with Mukhu River , 17.VIII.1955, A. L. Abramova & I. I. Abramov s.n. ( LE B 0000903 ) . Gudgora , 14.VII.2010, Ukrainskaya & Shilnikov s.n. ( LE B 0014637 ) ; Daut River valley , 5.VII.1993, Ukrainskaya s.n. ( LE B 0025512 ) . Kabardino-Balkarian Republic: Bezengi River gorge 1 km downstream Mizhirgi River mouth, 27.IX.1986, Portenier s.n. ( MHA9013704 ) ; Shkhelda Creek , a tributary of Adyl-Su Riv- er, 29.VII.2004, Ignatov, Ignatova & Kharzinov s.n. ( MHA9013709 & MHA9013711 ) ; Cherek-Bezengijsky Gorge , 20.VII.2000, Tuziev s.n. ( MW9030217 ) ; Adyr-Su River valley , 23.VII.1991, Ukrainskaya s.n. ( LE B 0025782 ) . Republic of North Ossetia – Alania: North Ossetian State Reserve, Tsei River gorge 21.VII.1976, L. I. Abramova s.n. ( MW9030221 & MW9030225 ) ; same place, 10.VII.2013, Ukrainskaya s.n. ( LE B 0015883 ) . GEORGIA: Dzhava Distr., upper course of Bolshaya Liakhva River , 17.IX.1947, I. Abramov s.n. ( LE B0000899 ) ; Republic of Dagestan: Gunib District , near station of Gorny Botanical Garden, Ignatov & Ignatova 09-360 ( MHA9013703 ) ; Charodinsky District: near Zayach’i gates, Fedosov 13-1-188 ( MW9132026 ) ; Karackskaja lesnaja dacha, Fedosov 13-1-137 ( MW9131992 ) .

Cynodontium gracilescens NORWAY: ST : Oppdal, Kongsvoll , 18.VII.1970, A . A . Frisvoll s.n. ( LE) . [ AUSTRIA] Tirolia (Vorarlberg), ad “Vermalen-Joch” prope Danöfen, C . Loitlesberger s.n., Kryptogamae exsiccatae №1071 ( LE). [ SWITZER- LAND] Wengrn Alp, Breutel 157 ( LE) .

Figures

Fig. 2. Cynodontium caucasicum (from holotype). A: habit, wet; B: habit, dry. C, E, F: leaf transverse sections; D: stem transverse section; G: upper leaf cells; H: mid-leaf cells; I–L: stem leaves; M, N: perichaetial leaves; O: perigonial leaf; P: basal leaf cells. Scale bars: 5 mm for A–B; 1 mm for I–O; 50 µm for C, E, F; 100 µm for G, H, P; 150 µm for D.

Fig. 1. A–D: Cynodontium gracilescens (from: [AUSTRIA] Tirolia (Vorarlberg), C. Loitlesberger s.n., Kryptogamae exsiccatae №1071, LE); E–J: C. caucasicum (F–G: from Russia, Kabardino-Balkarian Repub1ic, MW903217; E, H, I: from Russia, Dagestan, MW9111628); K–M: C. fallax (from: Adamstal in Mähren, J. Podpera s.n.: F. Petrak, Flora Bohemiae et Moraviae exsiccate, II Serie, №161, LE); N–R: C. asperifolium (from: Russia, Amurskaya Prov., N, P, Q, R – MW9079345, O – MW9118955). A–B, G– H, K, P: perichaetial leaves; C, F–E, L, N–O: stem leaves; D, J, M, Q: leaf transverse sections; I, R: perigonial leaves. Scale bars: 1 mm for A–C, F–I, K–L, N–P, R; 100 µm for D, J, M, Q.

Fig. 4. Distribution of Cynodontium caucasicum (red triangles) and C. asperifolium (blue circles) in Russia.