Dixa inextricata

Moulton, John K., 2016, The Dixa inextricata Dyar & Shannon (Diptera: Dixidae) species group, with two new cryptic species from the eastern Nearctic Region, Zootaxa 4121 (4), pp. 458-472 : 460

Dixa inextricata species group

Diagnosis. The most compelling synapomorphy known for this group occurs in the larval stage, which will be described elsewhere. The caudal process of these species has a longitudinal, dorsal row of spines medially, short and barely protruding in D. calciphila sp. nov., but much more developed in the other two species. The epiproct, typically a prominent, small, round, oval, subrectangular or triangular sclerite positioned between the 9th tergum and proctiger lobes of the male terminalia in related congeners, is reduced in this group (compare Figs 21–23 vs 24). The following characters serve to distinguish males of this group from all other known species of Dixa Meigen : scutum brown; wing hyaline, lacking infuscation; epiproct reduced; basal gonocoxal lobe subovoid to rounded, its greatest width ca. 1/ 3X length of gonocoxite, not extended beyond basal 2/3 of gonocoxite, horizontal margin not distended dorsally, resulting in no proximal bulge when viewed laterally; gonostylus triangular as seen in lateral view; restricted to the eastern Nearctic.

Figures

FIGURES 21 – 24. Male terminalia, 10 th tergum, dorsal view. 21, Dixa appalachiensis sp. nov.; 22, D. inextricata; 23, D. calciphila sp. nov.; 24, D. lobata Garrett. Scale bar = 50 µm.