Eurynogaster Van Duzee

Evenhuis, Neal L., 2005, A review of the genera comprising species of the genus Eurynogaster sensu Hardy & Kohn, 1964 in Hawai‘i (Diptera: Dolichopodidae), Zootaxa 1017, pp. 39-60 : 50-51

Genus Eurynogaster Van Duzee

( Figs. 2, 7, 12b, 16, 24)

Eurynogaster Van Duzee, 1933: 339 . Type species: Eurynogaster clavaticauda Van Duzee, 1933 , by original designation.

Diagnosis: Species in this genus are generally small in size and are distinguished by the hypopygium having the cerci subtrapezoidal in shape with unmodified hairs, the dorsal lobe of the surstylus short with bristles; the ventral surstylar lobe apical setation without bristles or spines, and the apex of the hypandrium bifid ( Fig. 24). It is most similar in appearance to Adachia and can be separated from that genus by the generally shorter setation on the head, thorax, and abdomen (this general setation of Adachia very long and strong), and the presence of strong bristles on at least one pair of femora (bristles lacking on all femora in Adachia ).

Hypopygium ( Fig. 24). Extending forward only to posterior margin of 5th segment. In lateral view: cercus subtrapezoidal, variously clothed with hairs; surstylus bilobate, dorsal surstylar lobe with strong bristles or modified setae; ventral surstylar lobe without strong setation (some species with fine hairs apically); basiventral epandrial lobe subtriangular or rounded, bare; hypandrium forked apically; aedeagus sinuous, curved upward apically.

Discussion: Most species of this genus are relatively small (body length 2–3 mm). The larger and more commonly found species (especially in riparian habitats) previously considered as belonging in “ Eurynogaster ” are assigned here to either Uropachys , Sweziella , or Major . After transferring species in this study to other genera, there are now currently 24 species known in the genus.

Elmo Hardy (pers. comm.) had always considered Campsicnemus and Eurynogaster as “sister” genera in the Sympycninae in that the species with large, conspicuous, well differentiated male genitalia belonged in Eurynogaster (without an elaborate courtship behavior) and those species that possessed male genitalia with little or no specific characters belonged in Campsicnemus (with an elaborate courtship behavior). He felt that in these two dolichopodid genera mating recognition among males and females worked such that in Eurynogaster it was a lock­and­key mechanism based on the genitalia; while in Campsicnemus it was recognition by females of males of the same species based primarily on MSSC in the legs (consisting of striking modifications of structural shapes and setation) that were used as visual cues during courtship. This close phylogenetic relationship corroborated the hypothesis of Rentz (1972) in that related taxa for which one group had no elaborate courtship mechanism would have complex genitalia, while those that did have elaborate courtship would have more simple genitalia. This view of grouping Eurynogaster and Campsicnemus in the Sympycninae was followed by all workers since their placement together in the subfamily by Van Duzee (1933). However, re­examination of the male genitalia and chaetotaxy of the thorax and legs shows similarities in genitalic structures and leg and thoracic chaetotaxy with some genera currently placed in Hydrophorinae (e.g., Sigmatineurum , Paraliancalus ). A more thorough comparative morphological and phylogenetic study is necessary to ascertain the subfamilial placement of Eurynogaster and its allies within Dolichopodidae .

Included Species: Eurynogaster ablusispina Tenorio *, E. angusticerca Tenorio *, E. angustifacies Hardy & Kohn *, E. argentata Hardy & Kohn *, E. callaina Hardy & Kohn *, E. cilifemorata Parent , E. clavaticauda Van Duzee *, E. concava Tenorio *, E. furva Hardy & Kohn *, E. hawaiiensis Grimshaw , E. incompta Hardy & Kohn *, E. kauaiensis Hardy & Kohn *, E. maculata Parent , E. mediocris Tenorio *, E. obscura Tenorio *, E. obscurifacies Parent *, E. paludis Hardy & Kohn *, E. retrociliata Parent , E. spiniger (Grimshaw) , E. subciliata Hardy & Kohn *, E. tanyceraea Hardy & Kohn *, E. undulata Tenorio *, E. variabilis Hardy & Kohn *, E. vittata Hardy & Kohn *.