Morphological Characterization of Polychaete: Phylogenetic Insight into Eulepethids from Buntal Beach, Sarawak

Aiman Amanina, Amran (2024) Morphological Characterization of Polychaete: Phylogenetic Insight into Eulepethids from Buntal Beach, Sarawak. Masters thesis, Universiti Malaysia Sarawak.

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Abstract

Globally, over 10,000 polychaete species inhabit marine environment, from intertidal to deep ocean areas. In Malaysia, the taxonomic knowledge of this specific class remains inadequate, with a notable scarcity of comprehensive understanding. Moreover, an abundance of species within this class presents classification raises uncertainties or is under debate. Despite the longstanding documentation of 57 polychaete species across 30 families in Peninsular Malaysia since the early 1870s, Sabah and Sarawak have recorded only 11 species across 7 families. This project encompassed of morphological identification of all samples, and molecular analysis for the dominant species found in intertidal zone of Buntal Beach, Sarawak. The first part integrated conventional identification method and SEM analysis, which led to the identification of 10 polychaete species. The identified species are (1) Buntalepis sarawakensis sp. nov. from Family Eulepethidae; (2) Glycera tridactyla, (3) Glycera alba and (4) Glycera tesselata from Family Glyceridae; (5) Micronephthys sphaerocirrata from Family Nephtyidae; (6) Onuphis eremita, (7) Onuphis sp. 1 and (8) Onuphis sp. 2 from Family Onuphidae; (9) Euchone sp. 1 from Family Sabellidae; (10) Scolelepis (scolelepis) squamata from Family Spionidae;. With a total of 116 individuals collected, the Eulepethidae species were found dominant, representing 22% of the samples, while the Spionidae species was the least abundant, comprising only 3%. Morphological analysis of Eulepethidae species revealed distinct characteristics, including a fixed position of the starting posterior lamellae and the presence of unique middle neurochaetae, differentiating them from other genera and species within the same family. Therefore, molecular analysis was conducted for the Eulepethidae species to further determine its evolutionary relationships and resolve taxonomic uncertainties. BLAST results for mitochondrial COI, 16S, and ribosomal 28S sequences of the Eulepethidae species revealed less than 85% similarity to its closest relatives in the Eulepethidae family. Phylogenetic analysis using MP, ML, and BI trees showed that the six isolates belonged to the Eulepethidae family but formed a well-supported monophyletic clade (100% bootstrap), distinct from the genera Eulepethus, Grubeulepis and Mexieulepis. Intriguingly, this study unveiled the identification of a new genus. This study documented 10 species with detailed identification and molecular data of a new genus, Buntalepis gen. nov., and its species, B. sarawakensis sp. nov., addressing scientific gaps in polychaete diversity, new species discovery, integration of conventional and molecular techniques, and insights into phylogenetic relationships, specifically at Buntal Beach, Sarawak. Keywords: 16S, 28S, Buntal beach, COI, morphological identification

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