Frullania hamatiloba Steph., Sp. Hepat.

Mamontov, Yu. S., Koroteeva, T. I. & Ezhkin, A. K., 2023, Frullania hamatiloba, а liverwort species new for Russia found in Sakhalin, Arctoa 32 (2), pp. 233-236 : 234-236

Frullania hamatiloba Steph., Sp. Hepat. 4: 400. 1910. ( Fig. 1 , 2 ).

Plants in thin dense mats, yellowish to deep dark brown, loosely adhering to substrate, irregularly branched; shoots to 1.5 cm long and 0.9–1.3 mm wide. Stems rounded, 140–190 µm in diameter, light to dark or almost blackish brown. Dorsal leaf lobes slightly concave and imbricate (in view from above), widely reniform to widely obovate, 650–850 µm long, 460–630 µm wide, ca. 1.34–1.55× as long as wide; antical base mostly not auriculate or only weakly so (but sometimes bear an ovate appendage of ca. 0.5–1.0 of the lobule size), extending ca. stem-width across and beyond the farther edge of stem, postical base not cordate; apex of lobes broadly rounded; margins entire. Lobules inflated or explanate, when inflated 0.1–0.15 of the size of the lobes, transversely ( Fig. 2C, D, H ) to longitudinally elongated, 200–250 µm high, 160–310 µm wide, ca. 0.7–1.5× as high as wide; the lobules widely cucullate, their upper part distinctly saccate, inflated to the substrate, antero-upper part inclined or inflated, postero-upper part inflated, the rostral portion distinct, tubular; the lobule beak distinct, well-developed, nearly straight or incurved toward both lobule base and substrate, short to rather long (up to 1/2 of the lobule width, Fig. 2H ), rounded to obtuse, hoof- to gouge-shaped, without apical hollow; the mouth convex or truncate or nearly straight, compressed, the dorsal valve more or less wrapped up inside the mouth to form a fold ( Fig. 2D ), the ventral valve nearly plane to slightly reflexed postically, the mouth opening to the sustrate, the keel ca. 0.2– 0.3 of the lobule width. Stylus indistinct, filiform, 1(–2) cells wide at base, 3–5 cells long, sometimes ending by slime papilla. Cells in the lobe middle rounded hexagonal, with medium to rather large, usually convex (rarely concave) trigones and with intermediate thickenings; near the lobe apex the trigones somewhat smaller and the intermediate thickenings rarely present; median cells ca. 23–29(–35)×20–25(–29) µm, marginal cells smaller, nearly quadrate or slightly elongated, 14–19(–22)×11– 17(–23) µm; cells near the base larger, 27–35(–46)×24– 30(–36) µm. Oil-bodies not seen. Ocelli lacking. Underleaves nearly transversely inserted, (370–)400–600 µm long, (350–)410–550(–690) µm wide, 0.75–1.25× as long as wide, 1.8–3.7(–4.4) times as wide as the stem, widely reniform or obovate or orbicular, widest mostly in the upper third, rarely near the middle, the lower half often obcuneate, with the margins widely reflexed to revolute postically, in upper half the margins not revolute, entire or with an angulation on both sides; the underleaves almost undecurrent or somewhat decurrent ( Fig. 2G ), with line of insertion straight to slightly arched; the apex bilobed ca. 0.18–0.26 of the length, sinus mostly acute, rarely rectangular, margins straight to concave, entire; the lobes obtuse to acute at apex, the outer margins nearly straight to convex in less-developed underleaves, but concave in well-developed ones ( Fig. 1C , 2B, E, I ). Asexual reproduction unknown.

Dioecious. Androecia not seen [in terminal on short lateral branches, usually subglobose (button-shaped), compact, of 4–5 pairs of densely imbricate bracts. Bracts subequally bilobed, lobules near the middle or in upper third with small, filiform stylus 1–2 cells at base and up to 4 cells long. Bracteoles free, with entire to angulate margins; upper bracteoles very small and sling-shaped, 130–150 µm long, 60–120 µm wide, bifid ca. 0.7 of the length, with rectangular sinus, with the lobes filiform, consist of conical base 2×2 cells and a uniceriate tip 5–7 cells long; the bracteoles near the base almost rectangular, 320–360 µm long, 80–140 µm wide, bifid ca. 0.31– 0.39 of the length, with acute lobes and acute-angled sinus.] Unfertilized gynoecia terminal on main shoots or on lateral branches. The bracts in three gyres, unequally bilobed, with entire margins, innermost bracts divided 0.75–0.85 of the length; lobes more or less concave, broadly oval to ovate, 970–1110 µm long, 550–700 µm wide, apex rounded; lobules long lanceolate, strongly canaliculate to involute postically, 600–700 µm long, 120–200 µm wide, apex acute to acuminate; stylus at base of lobules, filiform, 2 cells at base and 4–6 cells long, ending by slime papilla; an additional cilium identical to the stylus also present in the base of each lobule, just near the stylus. Bracteoles free from bracts, 450–600 µm long, 220–350 µm wide, at base with 1–3 cells cilia, bilobed 0.6–0.88 of the length, sinus acute-angled, lobes narrowly triangular, but strongly canaliculate to involute, entire margined, lobes divergent from, or crossing, each other, ± strongly curved postically, apex acute to apiculate. [Perianth exserted from 1/2 to 2/3 of the length, obovate to obpyriform, 1380–2510 µm long, 1030–1130 µm wide, with two lateral keels and one high and sharp ventral keel; the surface tuberculate mostly in lower two thirds; the apex subtruncate or ± retuse, with the beak 98–145 µm long; the beak apex crenulate.]

Distinction. Among Frullania species known in Russia, F. hamatiloba is rather remarkable due to transversely to longitudinally elongated lobules, shallowly bilobed underleaves and tuberculate perianth surface. However, since the species was found in Sakhalin without perianths, the comparison between F. hamatiloba and other similar species is provided below to include features of sterile plants only. The species F. kagoshimensis Steph. , F. taradakensis Steph. and F. usamiensis Steph. (two latter are known in the south of the Russian Far East) are similar to F. hamatiloba in rather large shoots, the shape of transversely elongated leaf lobules and the shape of underleaves in some phases. However, in the former three species the underleaves are broader in relation to the stem width (usually 4–5 times) than in F. hamatiloba . Moreover, in F. taradakensis the well-developed underleaves are cordate at base, widest at most below the middle, gradually narrowed to the apex, while the underleaf margins are entire, plane or only slightly reflexed in lower 1/4 of rather less-developed underleaves ( Kamimura, 1961: Fig. XVII: 15, 16). In F. usamiensis , the underleaves are usually less deeply bilobed than in F. hamatiloba , that is emarginate or bilobed to 0.13 of the length. Moreover, in both F. kagoshimensis and F. usamiensis the underleaf margins are entire (without distinct angulation) and usually plane (not revolute or reflexed postically in lower half). The species F. fauriana Steph. and F. osumiensis (S. Hatt.) S. Hatt. , known from Japan, also resemble F. hamatiloba in the shape of transversely elongated leaf lobules and shallowly bilobed underleaves; however, both former species differ from F. hamatiloba by the underleaves dentate in upper half and the underleaf margins neither revolute or distinctly reflexed in lower half. The species F. pedicellata Steph. is similar to F. hamatiloba in the shape of longitudinally elongated leaf lobules, however, it easily differs from the latter by the underleaf margins mostly plane (not or slightly reflexed) in lower half, and toothed in upper third of relatively well-developed underleaves ( Kamimura, 1961: Fig. 5: 1–4, 10, 13– 15, 28).

Distribution. Japan: Hokkaido, Honshu, Shikoku, Kyushu including Yakushima I. ( Kamimura, 1961; Yamada, Iwatsuki, 2006); Republic of Korea ( Kamimura 1961, Hong, 1997): China: Anhui, Guangdong, Taiwan ( Piippo, 1990); Russia: Sakhalin (present study).

Ecology. According to Kamimura (1961), F. hamatiloba occurs on bark of deciduous broad-leaved and coniferous trees, rarely on rocks or decayed logs, in the deciduous broadleaved forest zone, at altitudes of 500– 1300 m.s.m., associated with other Frullania and species of the genera Cheilolejeunea , Lophocolea , Porella , Radula . In Sakhalin, F. hamatiloba was collected on bark of Ulmus sp. in deciduous forest, in pure mat about 10 cm 2.

Specimens examined: Russia: Sakhalin Region, Sakhalin Island, vicinity of Yuzhno-Sakhalinsk City, the valley of Rogatka River , 46°58’5.707”N, 142°47’’49.03”E, 160 m a.s.l., floodplain forest with Populus maximoviczii and Ulmus sp. , on bark of Ulmus sp. , 19.V.2014, A.K. Ezhkin 240 (MHA 9088498, gynoecial plants with unfertilized gynoecia). Japan: Honshu: Shiga Prefecture, Kanzaki-gun, Eigenji-cho, Mt. Fujiwara , 5.IV.1952, N. Takaki 13560 (MHA 9088499). Miyagi Prefecture, Tenshudai, Sendai , 20.X.1907, E. Jishiba 6 (G-00280791, syntype of F. hamatiloba , androecial plants). Iwate Prefecture, Morioka , 20.X.1907, 18.VIII.1999, K. Sawada 38 (G-00280788, syntype of F. hamatiloba , gynoecial plants with perianths and sporophytes). Niigata Prefecture, Kitanbaragun, Sasagamimura, Deyu , 11.VI.1961, Y. Ikegani 63458 (NICH 71706, holotype of F. hamatiloba var. latistipula S.Hatt. ).

Figures

Fig.1. Frullania hamatiloba (all from Ezhkin 240, MHA 9088498): A: portion of gynoecial shoot with unfertilized gynoecia; B, C: sterile shoot fragments showing leaf lobules and underleaves, respectively.

Fig. 2. Frullania hamatiloba (all from Ezhkin 240, MHA 9088498): A: sterile shoot fragments showing leaf lobules; B, E, F, G, I, J: underleaves; C, D, H: enlarged leaf lobules.