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-A total of 66 species of Candoninae have been described or recorded from North America in the period between the years 1894 and 1990.

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The recent representatives of the subfamily Cyclocypridinae Kaufmann, 1900 are revised here, based on some newly collected Australian material, as well as an extensive study of type material of already described species deposited in various museums. The following two new genera are proposed: Kempfcyclocypris gen. nov. and Keysercypria gen. nov. The genus Kempfcyclocypris is erected to include single new species from subterranean waters of New South Wales, Australia. Kempfcyclocypris australis gen. et sp. nov. can be distinguished from other members of the subfamily by the following characters: 6-segmented antennula, absence of the sexual bristles on antenna, weakly asymmetrical prehensile palps, absence of the basal seta on the second thoracopod, and the long distal seta on the penultimate segment of the third thoracopod. Keysercypria is erected to include some South American species previously described in the genera Physocypria Vávra, 1897 or Cypria Zenker, 1854. The main characters of this genus are: rather globular carapace, with or without marginal tubercles; very short setae on endopodal segments of the third thoracopod; unequally long setae “h1” and “h2” on the terminal segment of the same appendage; and the presence of the basal seta on the second thoracopod. Keysercypria affinis (Klie, 1933) comb. nov. is chosen as the type species and, together with K. deformis (Klie, 1940) comb. nov., K. longiseta (Klie, 1930) comb. nov., K. obtusa (Klie, 1940) comb. nov., and K. pellucida (Sars, 1901), redescribed in the present paper and lectotype and paralectotype are designated. After examining and redescribing the type species of the genus Physocypria Vávra, 1897, P. bullata Vávra, 1897, the genus Mecynocypria Rome, 1962 is synonymised with Physocypria. Lectotype of P. bullata is here designated. For each valid genus a diagnosis, a key to species and a distribution map are provided. A list of six genera and 87 species, currently belonging to the subfamily Cyclocypridinae, is given at the end of the paper, along with their synonyms. Twenty four species are not included in the keys due to lack of data; these are also listed at the end of the paper.

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Seven species of the family Candonidae Kaufmann, 1900 are reported from South Korea. Five species are described as new, all belonging to the subfamily Candoninae Kaufmann, 1900 and the tribe Candonini Kaufmann, 1900: Candona quasiakaina sp. nov., C. sillae sp. nov., Fabaeformiscandona koreana sp. nov., Typhlocypris choi sp. nov., and Schellencandona tea sp. nov. A very close resemblance between Candona sillae and the European C. improvisa Ostermeyer, 1937 prompted a redescription of the latter species based on the type material, and designation of the lectotype. One species of the tribe Candonopsini, Candonopsis transgrediens Brehm, 1923, previously known only from China, is reported from Korean freshwater habitats, and its first redescription is provided, along with a key to the world representatives of the genus Candonopsis Vávra, 1820. One species of the subfamily Paracypridinae, Dolerocypria mukaishimensis Okubo, 1980, previously known only from Japan, is redescribed from Korean brackish water habitats, and some notes on its variability are provided. A checklist of the Candonidae ostracods from East Asia is also provided, but only for those species that have been well-documented and taxonomically described.

Ostracods are drastically reduced crustaceans, with never more than eight appendages enclosed between two valves, leaving only a limited number of morphological characters for species delineation. Conservative morphology of characters used to define genera, along with high variability of characters used to define species are creating problems in applying a morphospecies concept. A high intraspecific variability in a Lake Biwa (Japan) endemic, Physocypria biwaensis (Okubo, 1990), has been observed previously but was never studied in detail. Two sympatric forms, differing in pigmentation and size, suggest a presence of reproductive isolation. The aim of this study is to employ molecular and morphometric tools to aid in species delineation within P. biwaensis complex and reconstruct their phylogenetic relationships. A fragment of the mtCOI gene was amplified from 30 specimens, and an additional 37 specimens were studied for morphological characters. Resulting phylogenies showed that each morphologically distinct form is associated with a distinct phylogenetic group based on mtDNA. The average pairwise distance is very low (5%), indicating a recent divergence time. I speculate that there is a possibility that one of them originated in the lake, while the other probably colonized it afterwards. This seems to be supported with an apparent niche partitioning at different depths. In spite of the fact that traditionally used sexual characters are highly variable in these two species, the morphometric analysis of shell and soft part related characters clearly delineates them and suggests that such characters may be useful for future detection of seemingly cryptic ostracod species.