Euconnus (Euconnus) takachihoi Hoshina, 2015

Jałoszyński, Paweł, 2022, Euconnus Thomson of Japan: redescriptions of species established by Reitter, Sharp and Franz, new synonyms, and summary of current state of knowledge (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 5093 (1), pp. 1-37 : 28-29

Euconnus (Euconnus) takachihoi Hoshina

Euconnus (Euconophron) takachihoi Hoshina, 2015: 195 .

Euconnus (Eupentarius) takachihoi Hoshina ; Jałoszyński, 2021a: 156, implied, by placing Euconophron as junior synonym of Eupentarius.

Euconnus (Euconnus) takachihoi Hoshina ; here placed in Euconnus s. str.

Euconnus kusunokii Hoshina, 2019a: 52 ; syn. n.

Euconnus itsuki Hoshina, 2019a: 56 ; syn. n.

Remarks. This species is known to occur on Honshu, Kyushu, and Shikoku, and also belongs to the E. fustiger group.

The type series of E. takachihoi included four males, the aedeagus was illustrated possibly intact, and the body length of this species, ranging from 1.70 to 1.90 mm, is similar to that of E. raucus . In fact, the aedeagus illustrated for E. raucus by Hoshina (2019b) is similar in shape to that of E. takachihoi , and has a similar unpaired elongate median sclerite in the endophallus. However, the genital organ shown in Hoshina (2019b) is partly erected, its median lobe clearly distorted, the ventral apical plate flipped ventrad, and the endophallic sclerites displaced. For this reason, it is not possible to directly compare these illustrations. It cannot be excluded that they show the same species. The situation is complicated by the fact that it is unclear whether the aedeagus illustrated by Hoshina (2019b) truly belongs to E. raucus (see remarks in previous section of this study, at E. raucus ). Hoshina (2015) stated that E. takachihoi differs from E. raucus in having the HW/PW ratio 0.86 vs. 0.69 in E. raucus . I measured the HW/PW in the holotype of E. raucus as 0.73, and some variability in proportions of body parts is not unusual within one species of Euconnus . The body length approaching 1.9 mm suggests that E. takachihoi may also be similar to E. kojiroi . The aedeagi seem to differ, although the erected condition in the illustrated aedeagus of E. kojiroi makes comparisons hardly possible. I conclude that status of E. takachihoi remains unclear.

Hoshina (2019a) described E. kusunokii and made a remark that it is similar to E. takachihoi , but differs in having “the median lobe of aedeagus box-shaped in ventral and dorsal views and bearing a bifurcated projection whose apexes are remarkably extended”. As already described in previous paragraphs, and illustrated in Figs 32–49 , the shape of the thin-walled median lobe of all species within the E. fustiger group is highly prone to distortions and it is difficult to obtain two preparations from a long series of specimens collected on the same spot with exactly the same shape. Judging from the variability found among specimens of E. fustiger , E. kusunokii is a junior synonym of E. takachihoi .

In the same paper, Hoshina (2019a) described E. itsuki and compared it to E. kojiroi . It is supposed to differ from the latter in “having the median lobe of aedeagus with a pointed projection at a ventro-apical corner”, vs. E. kojirioi having “the median lobe without projections at a ventro-apical corner”. It is true that this feature differentiates the analyzed illustrations. However, the most similar species to E. itsuki is in fact E. takachihoi , judging from descriptions and illustrations. The aedeagus illustrated for E. itsuki is badly distorted (the median lobe is misshaped, the silhouette of the median lobe presented in ventral and dorsal views strikingly differs, and the endophallus is partly extruded), but it seems that the male genitalia of E. itsuki , E. kusunokii and E. takachihoi are nearly identical. The differences seen in figures are either artifacts of preparation (distorted shape of the median lobe and altered arrangement of endophallic structures) or fall within interspecific variability (shape of the dorsal median apical plate). My conclusion is that E. itsuki is a junior synonym of E. takachihoi . However, I cannot exclude a possibility that all these names are junior synonyms of E. kojiroi

As a member of E. fustiger group, E. takachihoi also belongs in Euconnus s. str.

Figures

FIGURES 31–49. Euconnus fustiger, male. Dorsal habitus of specimen from Kanagawa Pref. (31); aedeagus in ventral (32, 34, 36, 38, 40, 42, 44, 46, 48) and lateral (33, 35, 37, 39, 41, 43, 45, 47, 49) views of specimens from prefectures: Hiroshima (32–35), Saga (36–37, 42–43), Hyôgo (38–41), Kanagawa (44–45), and Ibaraki (46–49), showing examples of variability.