Integrative taxonomy of east Asia Physocypria complex (Crustacea, Ostracoda)

초록

In the genus Physocypria V & aacute;vra, 1897, as in many freshwater ostracods without prominent carapace ornamentation and with conservative appendage morphology, typological taxonomy led to an underestimation of biological diversity and notion of widely distributed species with significant morphological variability. Molecular studies, in combination with linear morphometrics, revealed some members in East Asia to be species complexes, but did not lead to formal descriptions, as is often the case with research on cryptic species. Here we combine macro-morphological taxonomy with a phylogenetic study of two mitochondrial genes (COI and CytB) and landmarkbased geometric morphometrics (LBGM) of the carapace and two appendages on Korean and Japanese members of this genus, with P. kraepelini M & uuml;ller, 1903 from Germany as an outgroup. Two new species are described: P. hyunsuyooi n. sp. from Korea and P. smithi n. sp. from the ancient Lake Biwa in Japan. We confirm the validity of the Japanese P. nipponica Okubo, 1990 and challenge the Palearctic distribution of P. kraepelini, and its presence in East Asia. The Japanese P. biwaensis (Okubo, 1990) was detected with molecular tools in Korea and China, which is its first record outside Lake Biwa. Principal Component Analysis of the carapace resulted in a clear morphospace clustering of species, but appendages prove impractical for LBGM species delineation. Species living in sympatry differ significantly in centroid size, suggesting size differentiation as an evolutionary mechanism. Despite high variability in male sexual characteristics within the genus, fine details of the morphology of the hemipenis, prehensile palps, and male second antenna may prove useful for distinguishing some species, highlighting the importance of fresh interpretation of morphological characters. Like in many other small invertebrates, integrative taxonomy was crucial for resolving species complexes, as no single method was sufficient for delineation of all five Physocypria species.

키워드