Sonerila konkanensis (Melastomataceae), a new species from South Goa, India

Abstract Resmi, S., S. Nampy & P.F. Akshatra (2021). Sonerila konkanensis (Melastomataceae), a new species from South Goa, India. Candollea 76: 139–143. In English, English abstract. A new tuberous species of Sonerila Roxb. (Melastomataceae, Sonerileae) from Chandreshwar hills, South Goa is described in the course of a taxonomic revision of the genus in India. Sonerila konkanensis Resmi & Nampy is similar to Sonerila talbotii G.S. Giri & M.P. Nayar and Sonerila sreenarayaniana Sunil et al. but differs in several characters that are detailed in the morphological discussion presented herein. The status of the new taxon is assessed as “Vulnerable” according to IUCN Red List Categories and Criteria. We also provide explanatory images of living plants as well as SEM images of pollen grains and seeds and information concerning the habitat. Received: August 29, 2020; Accepted: March 15, 2021; First published online: May 20, 2021


Introduction
Sonerila Roxb. is an Old World genus of the family Melastomataceae (tribe Sonerileae) comprising around 180 taxa and distributed in the Indo-Pacific regions (Cellinese, 1997;Resmi et al., 2018). It is the largest genus of the tribe Sonerileae in India with about 62 species having a sizeable percentage (83 %) of endemism. A proportionally high number of species have been described during the last ten years from the Western Ghats, which is considered one of the major centres of diversity for the genus with 53 species and two varieties. The genus includes caulescent/acaulescent herbs thriving in shady habitats, sometimes bearing tubers. After vegetative growth and flowering, the tubers undergo a period of dormancy within the humus-rich rock crevices, but with the retreat of monsoon develop into new shoots. The plants are usually herbaceous or suffrutescent woody herbs with simple or branched stems. Stems and branches are terete to quadrangular and glabrous to hairy (Lundin, 1983). The most remarkable features of the genus are the generally trimerous flowers, arranged in mostly uniparous (scorpioid) cymes, and the 3-locular, inferior ovary.
The authors have been collecting Sonerila since 2015 in the course of a taxonomic revision of the genus in India. During field surveys to Chandreshwar hills of Salcete taluk in South Goa, we found a tuberous, caulescent representative of Sonerila that could not be ascribed to any known species. We therefore formally describe the new species S. konkanensis Resmi & Nampy. A detailed morphological description, diagnostic characters, distribution data and a preliminary conservation status assessment are provided.

Materials and Methods
Relevant taxonomic accounts (Triana, 1871;Clarke, 1879;Cogniaux, 1891;Stapf, 1892;Lundin, 1983;Giri & Nayar, 1986;Sunil et al., 2014), herbarium specimens (CALI, MH, TBGT, CAL), and web-based herbarium resources available from BM, E, G, K and P were revised for discriminating purposes. The terminology proposed by Stearn (1992) and Giri & Nayar (1986) was adopted to describe the SEM aspects of the seed coat. Photographs were taken with an EZ 4HD stereo microscope with a 3.0 Mega Pixel Digital camera (Leica, Switzerland) and Stemi 508 stereo microscope (Zeiss, Germany) attached with an Axiocam 105 colour camera. Pollen descriptions were made following Patel et al. (1984) and Chantaranothai (1997). Material of living plants was maintained in the Calicut University Botanical Garden (CUBG) to observe variation under cultivation.
Etymology. -The specific epithet refers to the type locality, which lies within the region of iconic biodiversity called "Konkan". 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 km2. 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 B1ab(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