Anastrophyllum astorgae Mamontov & Vilnet, 2023

Anastrophyllum astorgae Mamontov & Vilnet , sp. nov. Fig. 2–6 View Fig View Fig View Fig View Fig View Fig .

Type: CHILE, Los Lagos Region, Palena Province, Chaitén Commune, Sendero Ventisquero Yelcho , 43°16’32.5” S, 72°25’31.0” W, 155 m a.s.l., evergreen-coniferous-bamboo-fern-moss forest, on tree, 29.XI.2021, Mamontov 928-3 (MHA-9088477 – holotype, CONC, G, KPABG, MO – isotypes) GoogleMaps .

Etymology. The species is named for Dr. Anna Beatrice Astorga Roine (Center for Research on Patagonia Ecosystems) for her great help in our study of bryophytes in southern Chile.

Diagnosis. A transversely to succubously foliated Cephaloziella -like liverwort with deeply bilobed leaves, differs from all species of Cephaloziella by the shape of mature sterile leaves and the larger ratio of their size to the stem diameter, from the similar Anastrophyllum crenulatum and A. novazelandiae by the more deeply bilobed leaves and the absence of nodular thickenings in leaf cells, from the similar Sphenolobopsis pearsonii (Spruce) R.M. Schust. by the absence of underleaves.

Description. In thin, depressed, yellowish to blakish brown mats; stems intricately interwoven or creeping as isolated stems among other bryophytes. Shoots 1–5 mm long, 160–610 µm wide, filiform, brittle when dry, prostrate, with shoot apices often attenuate. Stems 48–90 µm in diameter, 4–5 cells high in cross section ( Fig. 5M, N View Fig ), remotely furcate, branches intercalary, from leaf axils ( Fig. 4D, K View Fig ) or postical stem face ( Fig. 3I View Fig , 4D, I View Fig , 5I View Fig ); cortical cells 17–30 µm long, 13–18 µm wide, 1.0–2.3× as long as wide, rectangular, mostly thick-walled, in cross section almost equal in shape and size with that of medulla. Rhizoids sparse, scattered. Leaves remote, 180– 355 µm long, 155–270 µm wide, (0.94–)1.0–1.4× as long as wide, spreading or erect-spreading or squarrose ( Fig. 4D View Fig , 5I View Fig ) at base, concave ( Fig. 5B View Fig ) to conduplicate ( Fig. 5F View Fig ), lobes suberect or often nearly erect and parallel to stem, the lobe tips often incurved ( Fig. 5B, D View Fig ); leaves transversely to slightly succubously inserted, oblong-ovate to obovate or subquadrate, sinus descending to 0.35– 0.58 of the leaf length, V-shaped, at base acute to obtuse; lobes mostly subequal, rarely almost equal, divergent to suberect, narrowly triangular-ovate, acute to acuminate, (4–)5–8(–10) cells broad at base, margins entire or ± sinuous; lobes often terminated by 1–2 superposed cells. Cells equally thick-walled, at lobe bases 14–23 µm long, 10–15 µm wide, 1.0–1.5(–1.9)× as long as wide, subquadrate to rectangular; cuticle papillose with relatively small (in comparison with the size of the cell lumen), rounded to elongated papillae ( Fig. 6 View Fig ). Underleaves absent. Asexual reproduction not observed. Dioecious (?). Androecia not found, unfertilized gynoecia terminal on leading axis, always with innovations. Gynoecial bracts in 3 pairs, becoming gradually larger, the innermost bracts much larger than leaves but somewhat less deeply bifid (sinus descending to 0.39–0.52 of the bract length), leaflike, elliptic to ovate, 490–580 µm long, 320–470 µm wide, 1.24–1.52× as long as wide, sheathing at base, with acute and erect, lanceolate lobes; the margins entire or with 1–2 blunt teeth and/or a short appendage near antical base; bracteole vanishing.

Differentiation. Anastrophyllum astorgae is one of the most small-sized species of the genus; its Cephaloziella -like habit easily distinguishes it from all other species of Anastrophyllum . The underdeveloped minute shoots of A. crebrifolium can be confused with A. astorgae , however they are distinguished from the latter by the leaf margins crenulate via dilated septa between marginal cells (in A. astorgae the septae between marginal cells are not dilated, and the leaf margins are entire or somewhat sinuous). The distinctions between A. astor-

Anastrophyllum astorgae , a new species from Chile 167 gae and other species of the genera Anastrophyllopsis and View in CoL Anastrophyllum View in CoL listed for Patagonia in Hässel de Menéndez & Rubies (2009) are generalized in the key below. The key is based on the studied specimens of A. astorgae and A. crebrifolium , also the descriptions and illustrations of other species in literature: for Anastrophyllopsis involulifolia (Mont. ex Gottsche, Lindenb. & Nees) Váňa & L. Söderstr. in De Notaris (1855) and Engel (1978), for A. subcomplicata (Lehm. & Lindenb.) Váňa & L. Söderstr. View in CoL [as Anastrophyllum schismoides (Mont.) Steph. ] in Schuster (2002) and Engel & Glenny (2008), for Anastrophyllum ciliatum Steph. View in CoL in Stephani (1893), Gola (1923, sub A. pampaninii Gola ) and Engel (1978), for A. crenulatum R.M. Schust. and Venezuelan A. auritum View in CoL in Schuster (2002), and for A. semifissum Steph. in Stephani (1911).