Schizogyniidae Trägårdh, 1950

Trach, Viacheslav A. & Seeman, Owen D., 2014, A new genus and species of Schizogyniidae (Acari: Mesostigmata) associated with carabid beetles (Coleoptera: Carabidae) from Ukraine, Zootaxa 3793 (2), pp. 247-256 : 248-249

Schizogyniidae Trägårdh, 1950

Type genus: Schizogynium Trägårdh, 1950 , by original designation.

Diagnosis (based on Kethley 1977; Kim 2004; Lindquist et al. 2009). Adult mites with holodorsal shield. Sternal shield entire, bearing setae st1–3; presternal shields absent; metasternal shield(s) fused with sternal shield or free, and narrow, strap-like, entire or paired. Primary genital shields are paired latigynal shields, usually fused to ventral shield (free in Mixogynium ), and extending to at least the level of mid-coxa IV; mesogynal shield small, fused to ventral shield. Paired ventromarginal shields flank ventral shield; ventromarginal shield free from or fused with peritrematal shield. Ventral and anal shields fused, partially fused, or separate ventral and ventrianal shields. Hypostomal region usually sexually dimorphic, males often with modified hypostomal setae (male Indogynium and Euroschizogynium same as female). Excrescences on movable digit of chelicera rarely sexually dimorphic (male Indogynium bearing a scoop-like process, male Euroschizogynium with fewer short excrescences and longer serrate excrescence).

Remarks. The Schizogyniidae are part of the Celaenopsoidea, a well-defined monophyletic group of trigynaspid mites ( Kethley 1977; Kim 2004). The family-level classification is, however, not so well defined, being based primarily on the form of the female genital shields augmented by the arrangement of metasternal and opisthogastric shields. These arrangements of shields sometimes apply to most, but not all, taxa within a family, and in this regard the Schizogyniidae is no exception.

Schizogyniid mites are typically identified by having elongate latigynal shields that, along with the mesogynal shield, are fused to the ventral shield. Their metasternal shields also tend to be narrow strap-like plates or fused to the sternal shield ( Lindquist et al. 2009). Mixogynium is the exception, possessing free latigynal shields and large metasternal shields ( Ryke 1957; Hirschmann 1972). However, no other family seems appropriate for this genus, and we regard its elongate latigynal shields, combined with the fused mesogynal-ventral shield, characteristic of schizogyniid mites.

In contrast, the species Fusura civica is not a schizogyniid mite because its latigynal and mesogynal shields are obsolete, presumably being fused entirely with the ventral shields. Kinn (1966) had previously considered the species incertae sedis by excluding it from the Schizogyniidae , and Hunter & Rosario (1987) did not consider it in their overview of the family. Fusura civica is better placed in the Megacelaenopsidae as its arrangement of sternal and genital shields is almost identical to Megacelaenopsis oudemansi Funk, 1974 . A genus-level status for this species is still warranted, however, because of its hologastric shield.