Riccia sarieae A.E.D. Daniels & D.T.T. Daniels, 2022

Daniels, A. E. D. & Daniels, D. T. T., 2022, Riccia sarieae (Ricciaceae: Marchantiophyta) - a new species from a fragmented hillock of the Western Ghats, India, Phytotaxa 554 (2), pp. 201-205 : 203-205

Riccia sarieae A.E.D. Daniels & D.T.T. Daniels , sp. nov. ( Figures 1–2 )

Holotype: — India, Western Ghats, Tamil Nadu, Kanniyakumari District, Marunthuvazhmalai , an open hillock, on damp soil-covered rocks, at ca 40 m a.s.l, 08˚07.758ʹ N and 77˚30.851ʹ E, 2 October 2021, D.T.T. Daniels 17 (holotype: CAL; isotype: SCCN), 20, 34, 35 (Paratypes: SCCN).

Plants monoicous, in overlapping patches. Thallus 1.5–4 × 1–2 mm, simple or once dichotomously branched, lanceolate to oblong-lanceolate, bluish-green to rarely green. Ventral scales prominent, semilunar, not extending beyond margin, purple, closing over the dorsal surface when dry. Rhizoids numerous, smooth and tuberculate. Thalli dorsally sulcate towards apex and disappearing at base, twice or thrice as broad as high in cross section, ventrally convex, parabolic near apex with tubers; air spaces narrow, slit-like; epidermal cells quadrate to rounded-quadrate, hyaline, collapsing when mature with the lower part thickened and persisting, attached to a second layer of cells.Antheridia and archegonia along mid-dorsal groove; antheridial ostioles conspicuous. Sporogonia along mid-dorsal groove. Spores 64–80 × 48–64 µm, ovoid to roughly tetrahedral, crenulate, brown, 9–11 areolae on distal face; areolations ridged; triradiate mark faint.

Habitat: On soil-covered rocks, in open hillock, ca 40 m.

Distribution: India: Western Ghats, Tamil Nadu (Kanniyakumari). ( Figure 3 )

Specimens examined: INDIA. Western Ghats: Tamil Nadu, Kanniyakumari District , Marunthuvazhmalai , ca 40 m, 08˚07.758ʹ N and 77˚30.851ʹ E, 2 October 2021, D.T.T. Daniels 17, 20, 34, 35 .

Etymology

Named after Dr. Sarie Magdalena Perold (1928–2011), who was recognized as a leading authority on the taxonomy and nomenclature of African thallose liverworts, especially the genus Riccia .

Discussion

Riccia sarieae shows a close resemblance to the cosmopolitan species Riccia sorocarpa which shows a disjunct distribution in India by its occurrence on the Himalaya in the North and the Western Ghats in the South. However, some gametophytic characters and the spore morphology of the species in question are distinct from that of the putative species.

Riccia sarieae is a monoicous species with bluish-green thalli. In cross section, the thallus is roughly parabolic with the epidermal cells collapsing at maturity. These are characters more or less similar to that of R. sorocarpa . However, characters that can be attributed to R. sarieae are the presence of ventral tubers at the apex which are absent in R. sorocarpa , quadrate to rounded-quadrate epidermal cells which are ovate and mamillate at the apex in R. sorocarpa ; ovoid to roughly tetrahedral spores lacking an equatorial wing and distinctly ridged areolae versus spores that are tetrahedral and winged with faint ridges in the case of R. sorocarpa . Riccia sarieae also shows some resemblance to that of R. velimalaiana Daniels & Daniel (2002: 139) which possesses a simple or once dichotomously branched thallus, purple ventral scales, the crenulate spores lacking an equatorial wing. However, R. sarieae differs from the latter in having a lanceolate thallus not obovate; ventral scales not protruding beyond thallus margin but protruding in R. velimalaiana and spores being ovoid to roughly tetrahedral with a faint triradiate mark whereas in R. velimalaiana the spores are tetrahedral with a distinct triradiate mark. Riccia boliviensis Jovet-Ast. (1991: 242) , reported by Asthana and Srivastava (2021) from the Eastern Ghats of Peninsular India, has unique features such as green thalli with ventral scales extending beyond the thallus margin, tetrahedral spores with equatorial wing, vermiculate areolation and a distinct triradiate mark distinguishing R. boliviensis from R. sarieae .

Riccia sarieae completes its life cycle within a short span of time between the month of July and October.Although it was collected on exposed soil-covered rocks in Scrub forests, the prevailing forest type in that locality, it could not be found fresh before or after monsoon rains. On the other hand, the presence of tubers at the apex suggests that R. sarieae is more of an ephemeral species than a xeromorphic one.

Figures

FIGURE 1. (A–J). Riccia sarieae A.E.D. Daniels & D.T.T. Daniels A. Thalli B. Thallus with tuber C. Ventral view of thallus D–E. Cross section of thallus F. Assimilatory filaments with epidermal cells G. Assimilatory filaments after the collapse of epidermal cells H. Tuberculate rhizoids I. Spore distal face J. Spore proximal face (Drawn from D.T.T. Daniels 17)

FIGURE 2. (A–C). Riccia sarieae A.E.D. Daniels & D.T.T. Daniels A. Plants in situ B. Spore distal face C. Spore proximal face (D.T.T. Daniels 17)

FIGURE 3. Riccia sarieae A.E.D. Daniels & D.T.T. Daniels Location