Riccia junghuhniana Nees & Lindenb. ex Gottsche, Lindenb. &Nees

Riccia junghuhniana Nees & Lindenb. ex Gottsche, Lindenb. &Nees View in CoL , in C.M. Gottsche, J.B.W. Lindenberg & C.G.D.

Nees von Esenbeck, Syn. hepat. 4: 609 (1846)

Type citation: In Java Insula legit cl. Junghuhn (Hb. N. ab E.).

Type: INDONESIA. Java, s. dat., F. Junghuhn s.n. ( STR [image! (provided by STR)]).

[ Riccia luticola Na-Thalang auct. non Cargill et al., Austral. Syst. Bot. 29: 205 (2016)].

Figures 2–3 View FIGURE 2 View FIGURE 3

Description:— Thallus in half rosettes crowded or scattered from 9–26 mm in diameter. Light green when young, whitish green when mature with distinct pores, quite porous in older parts of thallus. Plants 1.4–14 mm long; 1.5– 3 mm wide; 1–3 furcate. Branches shallowly to deeply divided, segments oblong or spathulate; apex truncate or lanceolate. Dorsal groove shallow at base and distinct at the apex, narrow anteriorly, becoming shallower and broader posteriorly but persisting the entire length of segments. Cavities present throughout thallus. Ventral flanks are mottled hyaline or purplish maroon. Margins may be narrowly to broadly wing-like; irregularly crenulated along the entire thallus, sometimes wavy, sometimes inflexed, acute in transverse section. Scales present, 250–350 × 265–300µm, not readily seen, appressed along ventral flanks and across ventral surface as bands with irregular distal margins, cell walls straight, mottled hyaline and maroon. Cilia absent. Dorsal epidermal cells unistratose, hyaline, dimorphic, smaller cells surrounding air pores, globose to pyriform, wider than high. Thallus in transverse section biconvex-convex with margins reflexed to concave convex to campanulate to plano-convex; 310–730µm thick. Photosynthetic tissue with air chambers occupying from 1/5 to 1/2 of the thallus thickness, smaller air spaces also present throughout storage tissue. Rhizoids present on ventral side of the thallus, dimorphic, both smooth and pegged.

Monoicous. Gametangia in 1–3 rows either side of dorsal groove. Antheridia necks only seen. Capsules 1–17 per plant, mid-segment to base, embedded, seen from both the dorsal and ventral surface, bulging from ventral surface when mature, varying from pale brown to pale orange-brown to hyaline and black. Spores 65–95μm in diameter, globose to triangular-globose to ovoid in polar view, tetrahedral to hemispherical in equatorial view, 47.5–72.5µm high, light brown to golden-brown; wings up to 4.5–7.22 μm wide, incomplete, spore margin, irregularly crenulate and finely papillate. Distal surface ornamentation reticulate with elevated borders around the alveoli, varying in height, 6–13 alveoli across diameter, each 2–25µm in diameter. Proximal surface ornamentation similar to distal face, irregularly reticulate, alveoli frequently incomplete, 7–15 alveoli across each facet, alveoli 2.4–4.64μm in diameter, alveoli borders low and thin and vermicular. Triradiate mark indistinct, pores present.

Specimens examined:— INDIA. TAMIL NADU: Dharmapuri District. Grounds of P.D.R.V. College of Education. 14 th December 2020 Suresh N Abarna 005-1 & Suresh N Abarna 005-2; 15 th December 2020, Suresh N, Abarna005-3 (MH). Lat.:12.0895983, Long.:78.4787933.

Habitat and phenology:— Terrestrial, growing on black and red sandy loam soil, crowded in exposed, degraded sites in half and full rosettes. Plants observed growing after rainy season, in the month of January.

Distribution:— So far, known only in India from the grounds of college as described above. ( Fig. 1 View FIGURE 1 ).

The species has been recorded from Java (Gottsche et al. 1846), Central Java ( Schiffner 1900; Meijer 1958), Bali ( Jovet-Ast, 2003), The Lesser Sunda Islands, Indonesia; the Northern Territory of Australia ( Na-Thalang, 1980; Cargill et al 2021), New Caledonia (Thouvenot et al 2011, although this record is in doubt) and also from Zheijiang, China (Xiang, et al 2022).