Taxonomic notes on the ground beetles in the genus Trephionus Bates, 1883 from central Honshu, Japan (Coleoptera, Carabidae, Sphodrini, Synuchina)

Abstract

Trephionus Bates, 1883, a Japanese endemic genus in the subtribe Synuchina (Coleoptera, Carabidae, Sphodrini), is revised taxonomically based mainly on the shape of the endophallus, a membranous inner sac everted from the aedeagus of the male genitalia. Three known species from central Honshu, T. kinoshitai Habu, 1954; T. shibataianus Habu, 1978; and T. babai Habu, 1978, are re-defined based on this genital character, and five new species are described from the region: T. cylindriphallus Sasakawa, sp. n., T. niumontanus Sasakawa, sp. n., T. inexpectatus Sasakawa & Itô, sp. n., T. abiba Sasakawa & Itô, sp. n., and T. bifidilobatus Sasakawa & Itô, sp. n. The observed interspecies differences in endophallus morphology are discussed in terms of the species-level phylogeny and genus-level taxonomy of Trephionus.

Possible differences in effects on ejaculate morphology between shape and size components of the intromittent membranous part of insect male genitalia: Phylogenetic comparative analyses in Carabidae

“…In Amara, the first relative warp score constituted 47.4% of the total variance and was associated with the width of the endophallus; positive and negative values indicated wider and narrower shapes, respectively (Figure 1C). Because many related carabids have slender endophalli [Platynini: Habu (1978); Pterostichini: Sasakawa and Kubota (2007) and this study; Dolichina: Sasakawa (2006); Synuchina: Morita (2013) and Sasakawa and Itô (2018); Pristosiina and Calathina: Sasakawa et al (2006)], the slender shape is considered ancestral with evolution toward becoming wider; this character state change corresponds to the switch from negative to positive on the axis of the first relative warp score. In Pterostichini, the first relative warp score constituted 61.8% of the total variance and was associated with bending of the endophallus; positive and negative values indicated straight and ventrally bent shapes, respectively (Figure 2C).…”