Taxonomical Identity of ＂Rhizophora＂ × ＂annamalayana＂ Kathir and ＂Rhizophora＂ × ＂lamarckii＂ Montrouz (Rhizophoraceae) in the Andaman and Nicobar Islands, India

• Published in: TAIWANIA Vol. 60; no. 4; pp. 183 - 193
• Main Authors: P. Ragavan, R.S.C. Jayaraj, Alok Saxena, P.M. Mohan, K. Ravichandran
• Format: Journal Article
• Language: English
• Published: 台灣 臺灣大學生命科學院 01.12.2015; 國立臺灣大學生命科學院
• Subjects: Andaman and Nicobar Islands; hybrids; India; Mangroves; R. × annamalayana; R. × lamarckii; Rhizophora; SCIE; Scopus; TSCI; Rhizophora; Andaman and Nicobar Islands; Mangroves; R. × annamalayana; R. × lamarckii; hybrids; India
• ISSN: 0372-333X
• DOI: 10.6165/tai.2015.60.183

In India, Rhizophora hybrids have been recorded in Pichavaram (Tamil Nadu) and in the Andaman and Nicobar Islands (ANI). Rhizophora hybrids in Pichavaram mangrove forest were identified as Rhizophora × annamalayana, a cross between R. apiculata and R. mucronata, whereas Rhizophora hybrids in the ANI were identified as Rhizophora× lamarckii, a cross between R. apiculata and R. stylosa. However taxonomical distinction between them was not much explored. A recent floristic survey revealed the occurrence both R. × annamalayana and R. × lamarckii in the ANI, India. Based on critical analysis of specimens and morphometric analysis, it was found that both R. × lamarckii and R. × annamalayana can be distinguished from R. apiculata by their smooth green bract and bracteoles and 2-4 flowered inflorescences within the leaf axils. Rhizophora × annamalayana is distinguished from R. × lamarckii by its broader leaves (length: width ratio ＜1.8 vs ＞1.8), and shorter style (＜1.5 mm vs. ＞ 1.5 mm) and stamens in two whorls vs. usually in a single whorl. Rhizophora × annamalayana is the new record from the ANI. Higher relative density of R. × annamalayana than R. × lamarckii in the ANI is attributed to the abundance of its parental species (R. apiculata and R. mucronata) in the ANI