Abstract
The Lower Mekong Basin is recognized as a region of notable biodiversity. However, it is currently experiencing serious degradation due to rapid economic development and the intensifying effects of climate change. Many species, including earthworms, are increasingly threatened. Besides, Aminthas mekongianus (Cognetti, 1922) exhibits considerable intraspecific morphological variability, which makes its identification difficult. Therefore, the study aims to clarify the boundaries of the species within the A. mekongianus complex in the lower Mekong River basin using both morphological and molecular approaches. Specimens were collected from multiple sites in the watershed and analyzes revealed at least two putative species. Phylogenetic reconstructions (NJ, ML and BI) together with species delimitation methods (ASAP, GMYC and bPTP) consistently supported the recognition of two distinct lineages. These lineages differ mainly in body length, number of segments, and spermathecae morphology. Consequently, they are recognized as A. mekongianus in a strict sense and A. sirindhornae Nantarat and Bantaowong, sp. nov.which is formally described in this document. This study improves understanding of the evolutionary complexity and taxonomic status of the group, providing a basis for future conservation and management strategies in the region.
Keywords: conservation, earthworm, phylogeny, systematics, taxonomy
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| A. coloration of life Amynthas sirindhornae sp. nov. B. surface casting and C. cocoon. |
Amyntas sirindhornae Nantarat and Bantaowong, sp. nov.
Diagnosis.-Elongated and cylindrical body with 419-494 mm length, width 65-70 mm. Four pairs of spermathecal pores in 5/6–8/9, slit-shaped. Half-ventral female pores on xiv. Male pores paired, on a round disc, protuberant, winged in xviii. Spermathecae ellipsoi-dal ampulla, diverticulum, long zigzag loops in the same plane. Testicular sacs paired in x and xi. Paired seminal vesicles in xi, xii. Paired prostate glands in xvii-xix. Simple intestinal cecum in xxvii-xxiv.
#Megascolecidae #Mekong #River #basin #descriptions #species
