Euconnus callidus, Casey, 1897

Jałoszyński, Paweł, 2022, Taxonomy of ' Euconnus complex'. Part XXIV. Intermediate forms between Psomophus, Eupentarius and Euconnus s. str. in the East Palaearctic fauna unify problematic subgenera (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 5194 (3), pp. 343-391 : 344-345

1. Euconnus callidus species group (‘true Psomophus ’)

The type species of the subgenus Psomophus is the Nearctic Euconnus callidus Casey, 1897 . Its body form and even the structure of the aedeagus (illustrated in Jałoszyński (2017c)) are highly similar to those of the Japanese E. debilis (Sharp, 1874) , redescribed by Jałoszyński (2022). Both species share clearly trimerous antennal clubs, round heads with bristles on tempora, subconical pronota narrowing anterad and bearing thick bristles on sides, protibiae in males with apices strongly bent mesad, and aedeagi with clearly delimited distal regions and an oval sclerotized median endophallic structure. Although some other species currently placed in Psomophus also show a similar set of features, only two more Eastern Palaearctic species so closely resemble E. callidus : E. chinensis Franz, 1985a [ China: Fujian], and E. nuperus Kurbatov, 2006 [Russian Far East: Amurskaya Oblast]. As E. debilis was recently redescribed in detail ( Jałoszyński 2022), and E. nuperus was adequately described and can be identified using Kurbatov’s (2006) accurate illustrations, only E. chinensis is redescribed below. A new species belonging in this group is here described as E. multiinsularis sp. n.

The above-listed set of morphological characters (except for the oval or ring-like sclerotized endophallic structure, which does not occur in some species) can be used to define a ‘true Psomophus ’. However, similar species are known, and also have been placed in Psomophus (see Discussion) that show a remarkably different form of the aedeagus or/and unmodified male protibiae. Such species are not included in the E. callidus group.