Fedosov, V.E., O.Yu. Pisarenko, A.V. Fedorova & E.A. Ignatova. 2024. Notes on the genus Chionoloma Dixon (Pottiaceae, Bryophyta) in the Russian Far East

Arctoa (2024) 33: 117–128

doi: 10.15298/arctoa.33.13

Chionoloma stenocarpum is newly recorded from Russia; it was collected in 2024 in three localities in Khasansky District of Primorsky Territory, close to its only known locality in Asia, Mt. Chang Bai in northeastern China. Molecular data confirm its segregation from C. tenuirostris; it occupies an orphaned position in a clade where C. minus, C. hibernicum, C. cylindrotheca and C. tenuirostris fall; its disjunct distribution in East Asia and East North America is considered as typical for relicts of Arcto-Tertiary flora. Two morphologically identical specimens of C. cylindrotheca collected in close sites in southern extremity of Primorsky Territory possessed different ITS sequences, suggesting classification within C. cylindrotheca s.l. for one specimen and within C. tenuirostre s.l. for another. According to the ITS data, the latter specimen groups with two GenBank accessions of C. cf. tenuirostre from Indian Ocean islands; however, according to the plastid data, these three specimens and the second specimen from Primorsky Territory appear in a clade sister to C. cylindrotheca s. str.-clade, thus showing a supported conflict of topologies. Therefore ancient reticulation event might have underlie the origin of this lineage, which we consider as a cryptic species within C. cylindrotheca. Morphological differentiation of C. cylindrotheca from similar C. tenuirostris is discussed. Descriptions and illustrations of C. stenocarpum and C. cf. cylindrotheca based on specimens from Russia are provided; they are supplemented by the key to identification of Chionoloma species known in Russia.