Drepanocladus jacuticus Ignatov & Ignatova, 2022

Ignatova, E. A., Kuznetsova, O. I. & Ignatov, M. S., 2022, A New Species Of Drepanocladus (Bryophyta) From Yakutia, Arctoa 31 (1), pp. 17-21 : 19-21

Drepanocladus jacuticus Ignatov & Ignatova , species nova. Fig. 3 .

Type: Russia. Republic Sakha / Yakutia, Tattinsky District , 62°20’28”N, 133°32’22”E, 154 m alt., surroundings of Ityk-Kyuel Settlement, permafrost hummock, on soil. 27 Jul 2016 Ignatov & Ignatova 16-1596 ( MHA9100592 ) (Holotype MHA!, isotype MW!)(DNA Isolate OK 2859, ITS: ON678000 ) .

Diagnosis: Drepanocladus jacuticus is similar to D. polygamus in having variable costae: simple, forked or double in leaves from the same plant, but differs from it in smaller size of plants; smaller leaves, 0.6–0.9× 0.3– 0.4 mm vs. 1.7–3.5×0.6–0.9(–1.1) mm; and alar cells small, subquadrate to transversely rectangular, firm-walled vs. large, oval, thin-walled in D. polygamus .

Description: Plants small, green or yellowish-green, in dense low tufts, weakly glossy. Stems ca. 1 cm long, irregularly branched, densely foliate, terete; branches 2– 5 mm long, terete-foliate; axillary hairs 2-celled, with upper cell ca. 60 µm long; proximal branch leaves of branch primordia subulate to triangular. Leaves loosely appressed to erect, with erect or slightly recurved acumina, 0.6–0.9× 0.3–0.4 mm, straight or weakly curved, from triangular-ovate or ovate base gradually tapered into long, narrow triangular acumina, gradually narrowed to the insertions, slightly concave; costae variable, simple, forked or double, to 0.2–0.5 the leaf length; margins entire or finely serrulate at leaf base; cells elongate-rhomboidal, 18–37×6–9 µm, cell length, µm/ leaf length, mm ratio 30–41:1, with moderately thickened, non-porose walls; alar cells quadrate and transversely rectangular, firm-walled, in moderately delimited alar groups. Dioicous? Gametangia and sporophytes unknown.

Other specimens examined: Republic Sakha / Yakutia, Khangalassky District , 61°20’40”N, 128°21’21”E, ~ 230 m alt., between settlements Ulakhan-An and Bestyakh , in larch forest on old rotten log, 2 Aug 2016 Ignatov & Ignatova 16- 244 ( MHA9131511 ); near previous locality, 61°21’48”N, 128°27’01”E, ~ 190 m alt., low-grass meadow, on soil, 3 Aug 2016 Ignatov & Ignatova 16-253 ( MHA9021822 ) .

Differentiation: Drepanocladus jacuticus was placed into the genus Drepanocladus as a result of molecular

phylogenetic evidence. In aspect it resembles depauperate Campylium chrysophyllum or Amblystegium serpens . However, the former species have more widely spreading to recurved leaves, while the former never has leaves with double costae. Differences of D. jacuticus from D. polygamus is given in the diagnosis; D. arcticus , another species with variable costae, is also a much larger plant, with larger leaves and U-shaped outline of leaf insertion.

Drepanocladus cardotii (Thér.) Hedenäs , known only from the type collection in high mountains in USA, Montana, is also a small plant with bifid costa and leaves similar to D. jacuticus . It differs from D. jacuticus in still larger leaves, 1.0–1.4× 0.7–0.8 mm vs. 0.6–0.9× 0.3– 0.4 mm; ratio of medial laminal cell length (µm) to leaf length (mm) 23.6 vs. 30–41: 1 in specimens of D. jacuticus (data on D. cardotii are given according to Hedenäs, 2014).

Ecology: Drepanocladus jacuticus was collected in mesic or xero-mesic meadows, some being flat or other being ‘hummocky’ from permafrost raisings ( Fig. 2 ). In all localities soil was somewhat salty (indicated by abundant Glaux maritima L. and occasionally present Sueda sp. ); the area has very low precipitation, 200–250 mm per year, and forest exists only due to permafrost melting (mean annual temperature in Yakutsk is 8.8°C below zero). Admixture species: in MHA9131511 (on rotten log): Sanionia uncinata (Hedw.) Loeske , Pohlia nutans (Hedw.) Lindb , Ceratodon purpureus (Hedw.) Brid. , Tomentypnum involutum (Limpr.) Hedenäs & Ignatov ; in MHA9021822 (on soil): Abietinella abietina (Hedw.) M. Fleisch. , Pterygoneurum kozlovii Laz. , P. subsessile (Brid.) Jur. , Didymodon cf. validus Limpr. (worth mentioning that in similar permafrost hummocks are common Aloina rigida (Hedw.) Limpr. and Pterygoneurum ovatum (Hedw.) Dixon , and once found Hilpertia velenovskyi (Schiffn.) R.H. Zander ).

Figures

Fig. 3. Drepanocladus jacuticus Ignatov & Ignatova (A–F, H–J, L–N – from holotype; G, K, O – from Russia, Yakutia, Khangalassky Distr., Ignatov & Ignatova 16-253, MHA9021822). A, H: habit, dry; B: stem transverse section; C: upper leaf cells; D, E: proximal branch leaves; F: axillary hair; G, I, K–M: leaves; J: mid-leaf cells; N, O: basal leaf cells. Scale bars: 5 mm for H; 2 mm for A; 0.5 mm for G, I, K–M; 10 µm for B–F, J. N–O.

Fig. 2. Habitat of Drepanocladus jacuticus near Ulakhan-An: ‘bulgunyakhs’ (local name for permafrost hummocks) at the edge of Larix forest (along the road, a mildly cow pastured area). Soil is salty, which is indicated by Glaux maritima (red color in photos).