A new species and a synopsis of the Hedyotis-Oldenlandia group (Rubiaceae: Spermacoceae) in Andaman & Nicobar Islands, India

Abstract

An identification key to all the reported species of Hedyotis-Oldenlandia group (Hedyotis, Oldenlandia, Exallage, Leptopetalum, Scleromitrion and Debia) in Andaman & Nicobar Islands is presented with one new species, Oldenlandia smita-crishnae, described from Saddle Peak forests of North Andaman, India. It shares some characters with Oldenlandia herbacea, O. corymbosa and O. pseudocorymbosa. However, it is remarkable for its abaxially puberulous leaves, divaricate stipules, ellipsoid to obovoid hypanthium, pink-striped corolla lobes and 20–30-seeded, inserted capsule. Furthermore, a new combination in Exallage is proposed and lectotypes for Spermacoce cristata, S. costata, Hedyotis vestita and Oldenlandia stocksii are designated.

Revisiting the Hedyotis–oldenlandia Complex in India, With a Note on Scleromitrion

“…(syn. Hedyotis hermanniana Ratna Dutta) (Figure 2B) and L. pteritum (Blume) Neupane & N.Wikstr., these being found in Southeast Asia, India and the Andaman Islands (Nandikar & Kishor, 2019).…”

“…Sectional and generic notes, nomenclatural novelties, distributional notes and new species records have been gathered from published literature and floristic accounts (Wight & Arnott, 1834;Beddome, 1874;Kurz, 1877; Hooker, 1880;Gamble, 1921;Blatter, 1934;Bremekamp, 1952;Yamazaki, 1966;Rao & Hemadri, 1973;Bremekamp, 1974;Babu, 1977;Henry et al, 1979;Henry & Swaminathan, 1982;Deb & Dutta, 1983, 1985, 1986a, 1986bSivarajan & Biju, 1990;Ravikumar, 1999;Murugesan & Balasubramaniam, 2007;Viswanathan & Manikandan, 2008;Karuppusamy & Ravichandran, 2014;Jose et al, 2015;Soumya et al, 2017;Nandikar & Kishor, 2019;Prabhukumar et al, 2019;Kumar et al, 2020). For the plant names and authors, the International Plant Name Index (Royal Botanic Gardens, Kew, Harvard University Herbaria & Australian National Herbarium, continuously updated) has been followed throughout the text.…”

“…Dutta & Deb, 2004). However, it can be separated from the other species in the Hedyotis-Oldenlandia complex by its axillary inflorescence and its crustaceous, hard, indehiscent, globose fruits with tumescent apices (Bremekamp, 1952;Neupane et al, 2015;Nandikar & Kishor, 2019) 1D) and E. ulmifolia (Wall.) Bremek.…”

“…Hedyotis congesta R.Br. ex G.Don is distributed in the Andaman Islands and Malaysia (Nandikar & Kishor, 2019). Its resemblance to Hedyotis prostrata Blume remains doubtful (Nandikar & Kishor, 2019).…”

“…ex G.Don is distributed in the Andaman Islands and Malaysia (Nandikar & Kishor, 2019). Its resemblance to Hedyotis prostrata Blume remains doubtful (Nandikar & Kishor, 2019). Neighbouring Sri Lanka is more speciose, having c.27 endemic taxa compared with c.26 taxa endemic to peninsular India.…”