The mating behaviour of the seed shrimpParapolycope spiralis(Ostracoda: Cladocopina), with insight into the evolution of mating systems in cryptic interstitial habitats

Three new interstitial species of the genus Neonesidea (Bairdioidea: Podocopida: Ostracoda) from the infralittoral zone in Japan

This study is the first to report on interstitial species of the genus Neonesidea: Neonesidea arenalocus sp. nov. from the Pacific coast of central Japan, Neonesidea alyamanai sp. nov. from the Pacific coast of south-western Japan, and Neonesidea alwakasaensis sp. nov. from the Sea of Japan coast of western Japan. All three species share a smaller carapace size than that of the epiphytic Neonesidea species; in particular, the carapace width and valve thickness are significantly less. Furthermore, the terminal claws on the walking legs are more linear than those of the epiphytic Neonesidea species. However, these three new species share a feature in the apical portion of the terminal claw on the males second antennae and asymmetric brush-shaped organs, which are common to this genus. In addition, the results of our field survey indicate that all three new species occur in coarse-grained sediments (coarse sand to pebbles) in the upper infralittoral zone, particularly on Miho-Masaki Beach, which contains an optimum zone for N. arenalocus sp. nov.

Congruence between male upper lip morphology and molecular phylogeny in Parapolycope (Ostracoda), with two new species from Korea

The ostracod genera Parapolycope Klie, 1939 and Kliecope Tanaka, Tsukagoshi & Karanovic, 2014 have a sexually dimorphic upper lip, and males use their lip during courtship. Here we study the male upper lip of 14 species in order to find homologous structures. For this purpose, the lip is divided into six homologous parts, determined by their relative position on the lip and the lip’s position in relation to other body parts. We found that the distal part (‘c’) is the most variable across taxa, probably due to high sexual selection. Six characters of the male upper lip are used in our cladistic analysis, along with another 12, in order to study phylogenetic relationships between Parapolycope species from East Asia. In addition, 18S rRNA is used to reconstruct molecular phylogeny and test the congruence between morphological and molecular data. The recovered topology on all obtained trees is almost identical, emphasising the importance of the male upper lip morphology in interpreting phylogenetic relationships in this peculiar ostracod group. Parapolycope viriosa, sp. nov. and P. widoensis, sp. nov. from marine interstitial habitats in South Korea are described here. To aid further identification of the 12 East Asian Parapolycope species we provide a taxonomic key.

Intraspecific variation in male upper lip morphology of Parapolycope watanabei n. sp. (Crustacea: Ostracoda) and its implications for speciation

The morphology of non-genitalic structures in males is often associated with mating and courtship, and the evolution of those structures may cause speciation. In the present study, we describe a new species of marine interstitial ostracod from Japan. Morphological comparisons and molecular phylogenetic analysis based on ITS (internal transcribed spacer) 1 and ITS2 sequences revealed intraspecific variation on the male upper lip in the new species. The male upper lip of Parapolycope Klie, 1936 species has been reported to be related to mating behavior, and it likely produces species-specific stimuli for the female. The results of this study suggest that the male upper lip morphology in Parapolycope changed at the early stage of the speciation process.