Cryptocolea imbricata var. minima Konstant., Vilnet et Mamontov, 2023

Cryptocolea imbricata var. minima Konstant., Vilnet et Mamontov , var nov.

Diagnosis. Cryptocolea imbricata var. minima is characterized by very small size of plants, numerous very long and dense rhizoids, transversely elliptical leaves with cells of leaves almost not differentiated, female bracts not reflexed, and in differentiation in ITS1-2, trn L-F and rbc L nucleotide sequences.

Holotype: RUSSIA: Krasnoyarsk Territory, Taimyr Peninsula, Bataika river valley, spotty Carex arctisibirica -lichen moss tundra, 71°12'48"N, 92°41'26"E, 29 July 2021, with Trilophozia scitula , Anthelia juratzkana, E.D. Lapshina 213 E /4-3-21 [ KPABG 124714]. Other specimens examined: Yamalo-Nenets Autonomous Okrug (Yugra), Nadymskiy District, dwarf shrub-lichen spotty tundra, on clay spot, 66°32'25"N, 73°52'9"E, 06.VIII.2019, E.D. Lapshina 385 E /3-4-19 [ KPABG 124450].

Etymology. The name reflects the very small size of plants.

The variety can be separated by the key below:

1. Plants medium-sized, shoots (0.7) 0.8–1.3 mm wide and more than (4) 5 mm long; leaves orbicular to broadly ovate, cells along margins and in upper part of leaf 20–25 µm, smaller than mid-leaf cells. ...... .......................................................... var. imbricata View in CoL

– Plants small, shoots 0.4–0.5 mm wide and 1–2 mm long; leaves, transversely elliptical up to 0.5–0.6 mm wide and just 0.4 mm long; leaf cells not differentiated, large, ca. 25–32×(30) 35–37 µm, including leaf margin................................................... var. minima

Differentiation. Cryptocolea imbricata View in CoL is a quite distinct species. Female plants of the species differ from all other species with rounded, non-serrated leaves in having characteristic inflorescences, which form compact heads of closely imbricate, concave leaves, with the apical and marginal part of bracts often patent to reflexed. One of the most important features distinguishing this genus from the species of other genera with undivided leaves is the rudimentary perianth completely hidden in the bracts. Oil-bodies are quite characteristic, composed of many granules that never occur in any species of Solenostomataceae View in CoL . It is more difficult to distinguish male plants; they are often differing, having quite specific bright golden brown to bright or dark bronze color, saucer-shaped, concave leaves, relatively large leaf cells, and pleasant smell of essential oil and relatively long persistent oil bodies composed of granules of various size. Fortunately, female plants occur in many specimens.

Ecology. The species occurs in wet calcareous sites both in lowland and mountain tundra belt. In the alpine belt of northern mountains the species grows on humuscovered or calcareous moist basic rocks, at base or in crevices of rocks where it occurs mostly mixed with oth- er bryophytes, but can sometimes form almost pure mats, as e.g. in the Kamchatka Peninsula and the mountains of South Siberia. Its associates are other not common liverworts like Gymnomitrion revolutum , Radula prolifera , Pseudotritomaria heterophylla , Frullania subarctica , or in moist calcareous sites in northern regions widespread and more or less common Calycularia laxa , Mesoptychia heterocolpos , M. sahlbergii , Scapania crassiretis , Trilophozia quinquedentata , Blepharostoma brevirete , etc. In “difficult” habitats such as spots in spotted dwarf shrub-lichen or moss lichen tundra with low moisture the species occurs as the small dwarf variety minima . In such sites the described variety occurs as isolated scattered shoots among other bryophytes, e.g., Tritomaria scitula , Anthelia juratzkana , and Jungermannia sp.

Distribution. Cryptocolea imbricata was described by Schuster (1969) from an isolated location in Minnesota and then recorded by him from one station in Michigan and many localities in Ellesmere Island and Greenland (l. c.). The species was later found in Alaska ( Steere and Inoue, 1978), Northwest Territories of Canada ( Damsholt, 2007), a single locality in Europe (northern Sweden, Schuster & Mårtensson, 1978), one in Svalbard ( Frisvoll & Elvebakk, 1996) and many localities in Asia, including its northern part (Konstantinova et al., 2009, Schuster & Konstantinova, 1996; Fedosov et al., 2015; Fedosov et al., 2020; Konstantinova et al., 2023), mountains of Yakutia ( Sofronova, 2018), South Siberia (Mamontov, 2013), and Far East of Russia ( Bakalin, 2010, 2015, Bakalin et al., 2021) ( Fig. 6 View Fig ). The species occurs from almost sea level in the tundra zone, e.g. in the Yamal Peninsula (Potemkin, 1993) up to 2000 m alt in the Kodar Range and Tardoki-Yani Mountains (South Siberia, Bakalin, 2015) or Kamchatka Peninsula (see specimens examined).

Thus, Cryptocolea imbricata can be characterized as an arctomontane, almost circumpolar species.