Solenostoma alaskanum Konstant., Vilnet & Mamontov, 2023

Konstantinova, N. A., Vilnet, A. A. & Mamontov, Yu. S., 2023, New species of Solenostoma (Solenostomataceae, Marchantiophyta) from Alaska, Arctoa 32 (2), pp. 151-157 : 154

Solenostoma alaskanum Konstant., Vilnet & Mamontov sp. nov.

Diagnosis. The species is characterized by medium-sized plants, numerous/ very long and sporadically dense, dark purple to dark red-brown rhizoids, stems with distinct hyalodermis, mostly two-lobed or emarginated, rounded-quadrate to oblong leaves, large granulate oil-bodies and differentiation in trn L-F and trn G-intron nucleotide sequences from other species of the genus.

Holotype: U.S.A., Alaska, Kenai Borough, 4.5 km South of Ingram Creek crossing on Hwy 1 south of Portage , along Ingram Creek , 60°50’N, 149°05’W. In pure mats on debris on moist cliff on bank of creek Coll. N. Konstantinova with D. Horton, R. M. Schuster, 29.06.1992 . Holotype KPABG 126087 , isotype MHA .

Etymology. The name refers to the U.S.A. state where the species was collected.

Description. Plants 2–2.5 mm wide and 2.2–3 cm long, with light green linear apices to dark green and almost black-green below in nearest part of shoots, with numerous ventral intercalary branches and stolons. Cells of dorsal stem surface very long, ca. (13)20–25×(30)50– 100 (150) µm. Stems in cross section 15–17 cells thick, round to widely elliptical, 225–280×300–350 µm, with distinct hyalodermis of large cells with slightly thickened lateral walls, 20–25×25–33 (35) µm, cortical cells in one or two rows distinctly smaller than outer cells, ca. (12)15–17×17–20 µm, thick-walled. Cells of medulla isodiametric, 17–25 µm, moderately thick-walled. Rhizoids numerous, very long and dense, dark red-purpleviolet to red-brown, over the whole ventral stem surface up to the apices. Leaves slightly obliquely inserted and just slightly decurrent on straight line dorsally and arched ventrally, leaf free dorsal and ventral zone absent. Leaves variable on one shoot, alternating several large and small, rounded-quadrate to oblong, distinctly elongate, varying on one shoot from 0.5× 0.6 mm to 0,7–0.75× 0.9 mm and 1.35× 1.30 mm, with a rounded extended ventral base and decurrent dorsal side, many leaves emarginate up to 0.8–0.1 of their length with slightly uneven, roundedobtuse lobes, but in some small leaves with one “lobe” blunt-pointed. Mid-leaf cells 17–22×(20)24–28 µm, with moderate trigones, at margins just slightly smaller, (15)17–20(25) µm, elongated along margin or perpendicular to margin, cells at base of leaves distinctly elongated, 22–24×(30)32–40(50) µm, cuticula striolate papillose. Oil-bodies 2–4 per mid-leaf cell, dark grey, spherical to ellipsoidal, finely granulate, 9–12×12–15 (17) µm immediately after soaking, preserved 30 years after collecting but rapidly disappearing when soaked. Cetera ignota.