ResearchPad - systematics-and-evolution https://www.researchpad.co Default RSS Feed en-us © 2020 Newgen KnowledgeWorks <![CDATA[Rapid divergent coevolution of <i>Sinopotamon</i> freshwater crab genitalia facilitates a burst of species diversification]]> https://www.researchpad.co/article/elastic_article_6762 One of the most striking radiations in brachyuran evolution is the considerable morphological diversification of the external reproductive structures of primary freshwater crabs: the male first gonopod (G1) and the female vulva (FV). However, the lack of quantitative studies, especially the lack of data on female genitalia, has seriously limited our understanding of genital evolution in these lineages. Here we examined 69 species of the large Chinese potamid freshwater crab genus Sinopotamon Bott, 1967 (more than 80% of the described species). We used a landmark‐based geometric morphometric approach to analyze variation in the shape of the G1 and FV, and to compare the relative degree of variability of the genitalia with non‐reproductive structures (the third maxillipeds). We found rapid divergent evolution of the genitalia among species of Sinopotamon when compared to non‐reproductive traits. In addition, the reconstruction of ancestral groundplans, together with plotting analyses, indicated that the FV show the most rapid divergence, and that changes in FV traits correlate with changes in G1 traits. Here we provide new evidence for coevolution between the male and female external genitalia of Sinopotamon that has likely contributed to rapid divergent evolution and an associated burst of speciation in this lineage.

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<![CDATA[ <i>Korotnevella hemistylolepis</i> N. Sp. and <i>Korotnevella monacantholepis</i> N. Sp. (Paramoebidae), Two New Scale‐covered Mesohaline Amoebae]]> https://www.researchpad.co/article/N02836338-e4d7-4f26-8297-0426c9ae4220 ABSTRACT. Two new species of Korotnevella Goodkov, 1988, Korotnevella hemistylolepis n. sp. and Korotnevella monacantholepis n. sp., are described from mesohaline ecosystems. The amoebae are characterized on the basis of light and electron microscopy with special emphasis on the structure of the basket scales, which have species‐specific architecture. The two new species are the second and third ones recovered from environments other than freshwater. In terms of scale morphology they most closely resemble a freshwater species, Korotnevella bulla (Schaeffer, 1926) Goodkov, 1988. Two genus names, Dactylamoeba Korotnev, 1880 and Korotnevella Goodkov, 1988, are in current use. The latter name is preferred, pending rediscovery and characterization of Dactylamoeba elongata Korotnev, 1880, the type species of the genus. Korotnevella species can be divided into three groups on the basis of scale morphology, suggesting that the genus may not be monophyletic. A key to species is provided.

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