Sonerila konkanensis Resmi & Nampy

Resmi, Sekarathil, Nampy, Santhosh & Akshatra, Pracy Fernandes, 2021, Sonerila konkanensis (Melastomataceae), a new species from South Goa, India, Candollea 76 (1), pp. 139-143 : 140-143

Sonerila konkanensis Resmi & Nampy , sp. nov. ( Fig. 1–2 ).

Holotypus: INDIA. Goa: South Goa Dist., Salcete taluk, Mulem , Chandreshwar hills , on the way to Chandreshwar temple, Ghat road cuttings, 15°13'16"N 74°01'59"E, c. 220 m, 3.IX.2019, fl. & fr., Resmi & Akshatra 164408 ( CALI! ; iso-: G!, MH!).

Sonerila konkanensis Resmi & Nampy differs from S. talbotii G.S. Giri & M.P. Nayar in petiole length (2–3.5 vs. 1–2 cm long), lamina shape (ovate to elliptic vs. elliptic to lanceolate), peduncle length (4–7 vs. 3–5 cm), flower number (6–20 vs. 3–12 per cyme), bract shape (ovate to elliptic vs. subulate) and petal shape (ovate to oblong vs. elliptic to oblong). The new species differs from S. sreenarayaniana Sunil et al. in root stock type (tuberous vs. non-tuberous), peduncle length (4– 7 vs. 8–13 cm), bracts (persistent vs. apparently absent) and petals shape (ovate to oblong vs. ovate-obovate).

Herbs perennial, erect, caulescent, 5–30 cm tall. Root stocks tuberous; tubers globose, 0.5–1.5 cm diam., white to pale green with tufts of roots all over. Stems angular with prominent leaf scars on nodes, sub-angular at the base, 0.2 –0.6 cm thick, green with a claret tinge, fleshy, corners distinctly marked with a dark pink colour, simple or branched; internodes 2–5 cm long, densely hairy at nodes. Stems, branches, petioles, laminae, bracts, peduncles, pedicels and hypanthia covered with dense glandular trichomes (trichomes <2.5 mm long). Leaves simple, decussate, sometimes clustered at the distal nodes; petioles adaxially grooved or canaliculate, 2–3.5 × 0.2–0.27 cm, green with a claret tinge towards apex; laminae ovate to elliptic, 3– 8 × 1.5– 4 cm, lime green adaxially, pale green abaxially, cordate or sub-rounded at base with non-overlapping margins, acute to acuminate at apex, densely glandular-hairy adaxially but only on midrib and lateral veins abaxially, margins serrate to dentate with each tooth ending in a terminal glandular trichome; veins pinnate, 2 pairs from the base and 2 to 3 pairs from midrib above, less branched, impressed adaxially, conspicuous abaxially. Inflorescences scorpioid cymose, terminal, unbranched, usually 1 to 2 cymes arising from the distal node of the stem and branches (sometimes 3 to 5), 6 to 20-flowered; peduncles angular, 4–7 × 0.15–0.25 cm, longer than petioles; bracts leaf-like, ovate to elliptic, 0.5–2.5 × 0.5–1.5 cm, persistent. Flowers trimerous, rarely tetramerous, 1–1.6 × 1–1.5 cm; pedicels sub-angular, 4–10 × 1–1.8 mm, longer in fruit, claret coloured. Hypanthia campanulate, 4–5 × 1.5–2.7 mm, 3-lobed, obscurely 3-ribbed, green with a claret tinge towards apex; lobes triangular, 1–2 × 1–2 mm, acute at apex. Petals 3, ovate to oblong, 8–12 × 4–5 mm, pale pink with a darker midrib, obtuse at base, mucronate at apex, glabrous adaxially, with glandular trichomes on midrib abaxially. Stamens 3, alternate to petals; filaments 5–6 mm long, dark pink, pale towards apex, glabrous, dilated and twisted downwards; anthers sagittate to deeply cordate at base, 5–6 mm long, yellow, acuminate to rostrate at apex, dehiscing through apical pores. Pollen grain 3-zonocolporate, oblate-spheroidal, striate with sculpturing parallel to the apertures and subsidiary colpi. Ovaries inferior, united with the hypanthium by half of its length, 2–2.5 × 2–3 mm; styles filiform, 8–10 mm long, dark pink, equal or shorter than stamens; stigmas capitate, pink, rugose, glabrous. Capsules urceolate, 4–5 × 4–5 mm, green with a claret tinge, obscurely 3-ribbed, densely glandular pubescent, many seeded. Seeds obovoid, 0.4–0.5 × 0.2–0.25 mm, pale brown; raphes not prominent; testae sparsely tuberculate at dorsal angle and densely pusticulate throughout; tubercles with broad base and head, not covered with pusticles, with somewhat smooth surface.

Etymology. – The specific epithet refers to the type locality, which lies within the region of iconic biodiversity called “Konkan”.

Distribution, habitat and phenology. – Known only from the type locality, Chandreshwar hills in South Goa district. It grows in wet humus and on damp rocks along the Ghat road cuttings, between elevations of 210– 280 m. Plants usually perennate by dormant tubers. It is found in association with Adiantum lunulatum Burm. f. (Adiantaceae) , Arachniodes aristata (G. Forst) Tindale (Dryopteridaceae) , Athyrium sp. (Athyriaceae) , Begonia integrifolia Dalzell. (Begoniaceae) , Cheilanthes sp. (Pteridaceae) , Exacum petiolare Griseb. (Gentianaceae) , Ixora sp. (Rubiaceae) , Leea asiatica (L.) Ridsdale (Leeaceae) , Lygodium flexuosum (L.) Sw. (Lygodiaceae) , Pteris scabripes Wall. ex J. Agardh (Pteridaceae) and Selaginella sp. (Selaginellaceae) . Flowers and fruits have been observed from August to September.

Conservation status. – Sonerila konkanensis is currently known only from one locality with two sub-populations in an unprotected area, separated by a distance of 200–300 m. A total of 90 mature individuals were found in an area of c. 4 km ². It is likely that more populations in similar habitats in the same hill are not yet known and further surveys are needed to determine the exact distribution range of this species. The type locality being a tourist destination, and considering the possibility of further ecological disturbances of this restricted range species, we provisionally assess the new species as “Vulnerable” [VU B1 ab(iii)] according to IUCN Red List Categories and Criteria (2012).

Notes. – Sonerila konkanensis is a tuberous species with angular stems, lime green leaves, pale pink flowers and acuminate to rostrate anthers. Many other species of Sonerila in India also have angular stems and tuberous root stocks but none of them are morphologically closely related to the new taxon. Sonerila konkanensis and S. talbotii are recognised by their stems, branches, petioles, laminae, peduncles, pedicels and hypanthia all covered by dense glandular trichomes. The density of the glandular trichomes on the laminae in S. konkanensis is variable and the glandular heads dry up when old. Sonerila konkanensis also differs from S. talbotii and S. sreenarayaniana in having obovoid seeds without prominent raphe (vs. ellipsoid with prominent raphe) and the testa tubercles somewhat smooth (vs. covered with small pusticles). This species is further characterised by its large (0.5–2.5 × 0.5–1.5 cm), leaf-like, persistent bracts, which are not reported in any other Sonerila species from India.

Additional specimens examined. – INDIA. Goa: South Goa dist., Salcete taluk, Chandreshwar hills, Chandranath , 16.IX.1997, Joshi & Rajkumar 962 (Goa University Herb.) ; near Bhoothnath temple, 9.IX.2007, fl. & fr., Ashish 532 (Goa University Herb.) ; on the way to Chandreshwar temple, [15°12'57"N 74°02'12"E], 273 m, 3.IX.2019, fl. & fr., Resmi & Akshatra 164409 ( CALI).

Figures

Fig. 1.– Sonerila konkanensis Resmi & Nampy.A–B. Plants in their natural habitat (see tetramerous flower within the same population); C. Cymes; D. Stem base showing tuberous root stock; E. Angular stem; F. Inflorescence; G. Tetramerous flower; H. Bract, adaxial view; I. Hypanthium; J. Ovate petals, adaxial view; K. Oblong petals, adaxial view; L. Hypanthium with stamens and pistil; M. Pistil; N. Stamens; O. Immature capsules; P. Mature capsules and a persistent bract. [Resmi & Akshatra 164408, CALI] [Photos: S. Resmi].

Fig.2.– SEM images of Sonerila konkanensis Resmi & Nampy. A. Pollen grains; B–C. Seed.