Resurrection of Astiotrema varanum (Verma, 1930) Mukherjee & Ghosh, 1970 with Restriction of Astiotrema impletum (Looss, 1899) Looss, 1900 to Freshwater African Tetraodontid Records.

Abstract

PURPOSE: Examine validity of records of Astiotrema impletum (Looss, 1899) Looss, 1900 which exhibit a taxonomically confused status due to their wide distribution across two continents (Africa and Asia) of ecologically non-connected and differing ecosystems possessing a diverse group of non-taxonomically/ecologically related hosts. METHODS: For addressing such an ambiguous situation, detailed morphological re-descriptions, molecular characterization, and species delimitation analyses were conducted using comparative morphology, discriminant multivariate analyses, and host-parasite data. RESULTS: The combined results of hierarchical agglomerative clustering, principal component, and linear discriminant analyses demonstrated morphometrical divergence between African and Asian records, revealed as two distinct, non-overlapping clusters consistent with their geographical separation. The primary drivers of the two groups' separation revolved around morphometric features linked to oral/ventral sucker proportions and egg size. Comparative morphology characterized Asian records from African ones by the cecal ends not exceeding the mid-level of the posterior testis, smaller eggs (20-34 μm), and curvilinear triangular testes in an obliquely tandem position. CONCLUSION: Our findings restrict the concept of A. impletum to include records from the African freshwater tetraodontid fish, the globe fish, Tetraodon lineatus Linnaeus. Astiotrema varanum (Verma, 1930) Mukherjee & Ghosh, 1970 (Syns. Astiotrema matthaii Gupta, 1954 n. syn.; Astiotrema sudarshani Mukherjee & Ghosh, 1970; Astiotrema varanusi Gupta & Jahan, 1979; Tremiorchis varanum Verma, 1930) is resurrected to provisionally include Asian records. Comprehensive sequence sampling of Astiotrema spp. and related genera are needed for demonstrating accurate internal relationships within the Astiotrematinae Baer, 1924. A key to taxa of Astiotrema Looss, 1900 is amended.