Reproductive biology and postembryonic development of a polyphagid cockroach Eucorydia yasumatsui Asahina (Blattodea: Polyphagidae)

Abstract

Reproductive biology, including mating behavior, ootheca deposition, ootheca rotation, and postembryonic development, were examined and described in a Japanese polyphagid, Eucorydia yasumatsui Asahina, 1971. E. yasumatsui lacks elaborate pre-copulation behaviors, in contrast to most cockroaches. On encountering a female, the male rushes to her, chases her, touching her with his antennae, and finally the pair initiates “tail-to-tail” copulation. The ootheca bears a well-developed, serrated keel along its dorsal median line and a flange on its anterior end, which is grasped with the female’s paraprocts while she carries the ootheca. The ootheca formed in the vestibulum emerges from her caudal end, with its keel upwards. Several hours later, she rotates the ootheca clockwise by 90°, viewed from the female’s side, into a horizontal position. After rotation, she carries the ootheca, maintaining this horizontal position for a few days, and then deposits it on the ground. The number of larval instars was 9 or 10 in females and 8 or 9 in males. Addition of annuli to the antennal flagellum occurs from the 2nd instar molting onwards, and annular division occurs both in the 1st annulus of the flagellum (meriston) and in the annulus following it (called “meristal annulus” from the 3rd instar on): one to several annuli from the former and a single annulus from the latter are added. Sexes can be distinguished from the 3rd instar on according to the changes of the postabdominal structures. Regarding exposed structures, in the female the posterior margin of abdominal coxosternum VIII becomes incised medially, the abdominal coxosterna VIII and IX retract, and the styli of segment IX disappear. The male does not undergo marked externally visible changes.

Phylogenetic reconstruction of Corydioidea (Dictyoptera: Blattodea) provides new insights on the placement of Latindiinae and supports the proposal of the new subfamily Ctenoneurinae

“…The macropterous males of Nocticola spp. also show morphological similarities with some latindiine species (Fujita et al, 2020; Lucañas & Foo, 2023). Therefore, the relationship between Latindiinae and Nocticolidae needs to be assessed in greater depth.…”

“…Nocticolinae possesses many specialized morphological features (e.g. slender legs, long antennae, degenerative eyes, ocelli, wings and their venations, Figure S27) that are characteristic of adaptations to specific environments, for example, cavernicolous, epigean, myrmecophilous or termitophilous (Fujita et al, 2020; Roth, 1988; Roth & McGavin, 1994; Shelford, 1910; Zhong Peng's personal observation for the myrmecophilous Nocticola ). Species of Ctenoneurinae are anatomically specialized, with no genital hook, and highly simplified left and right phallomeres.…”

“…Species of Ctenoneurinae are anatomically specialized, with no genital hook, and highly simplified left and right phallomeres. Despite the presence of numerous phenotypic specializations, Ctenoneurinae, Latindiinae and Nocticolinae still exhibit a number of similarities: small and delicate body (Qiu et al, 2016, 2017, 2019b; Roth, 1988; Silvestri, 1946, 1947; Trotter et al, 2017), clypeus usually small and non‐elevated (Lucañas, 2018; Qiu et al, 2016, 2017; Roth, 1988) and females with valvular subgenital plates (Fujita et al, 2020; Lucañas, 2018; Qiu et al, 2016, 2017; Silvestri, 1946) (Figures S25f, S26j, S27n, and S28m).…”

“…Thus, future studies could investigate the possibly inverse correlation of sexual dimorphism in eye size and tergal gland size (e.g. Nocticola , Figure S27e; Fujita et al, 2020).…”

“…Corydioidean cockroaches are found in diverse habitats, such as under plants in deserts, soil or humus, caves, under bark, inside decaying wood or social insect nests (Fujita et al, 2020; Grandcolas, 1996; Hopkins, 2014; Li & Huang, 2020; Qiu et al, 2017, 2018b; Roth, 1988). Species that thrive in these particular environments have evolved many unique morphological features that are thought to be adaptive.…”