Ditomyia euzona Loew

Fitzgerald, Scott J., 2020, Revision of the Nearctic species of Ditomyia Winnertz and a new species from the Neotropical Region (Diptera: Ditomyiidae), Zootaxa 4859 (2), pp. 239-262 : 243-244

Ditomyia euzona Loew

Figs. 2 , 11–16 , 18 , 48 (Map)

Ditomyia euzona Loew, 1869: 130 . USA: District of Columbia. HT female? (MCZC).

Material examined. CANADA: ONTARIO: Ottawa, nr. Uplands Airport , 21. VI.1990, J.M. Cumming, 1 female ( CNCI) ; NOVA SCOTIA: CBHNt. Pk., Lone Shieling , 4.VII.1983, swept along fast rocky stream, J. R. Vockeroth, 1 female ( CNCI) ; USA: NEW HAMPSHIRE: Franconia , Mrs. Slosson collection, 1 female ( USNM) ; Carr. Co., The Bowl , 2.5 mi. NW Wonalancet VIII 11/16 1984, D.S. Chandler, MT, 3 females ( UNHC) ; same except 27 VII–1 VIII 1984, 1 female ( UNHC) ; same except VI 21 /27 1984, 1 female ( SFC) , 4 males ( UNHC) ; same except VII 12/19 1984, 2 females ( UNHC) ; same except 28 VI–4 VII 1984, 1 female ( UNHC) , 1 male ( SFC) ; same except IX 2/17 1984, 1 male ( UNHC) ; Carr. Co., 2 mi. NW Wonalancet , 28 VI–4 VII 1984, D.S. Chandler, MT, 1 female ( UNHC) ; same except VII 20/26 1984, 1 female ( UNHC) ; same except VII 12/19 1984, 2 males ( UNHC) ; same except VII 21/27 1984, 1 male ( UNHC) ; Straf. Co., Spruce Hole , 3 mi. SW Durham, 21 VIII–2 IX 1987, D.S. Chandler, MT, 1 female ( UNHC) .

Diagnosis. The patterned wings ( Figs. 1 , 11 ) and terminalia ( Figs. 13–16 ) will distinguish this species from all other Nearctic Ditomyia .

Remarks. The holotype of D. euzona was listed by Loew (1869) as being male, but the specimen identified as the holotype in MCZC appears to be female from photographs available online (https://mczbase.mcz.harvard. edu/SpecimenResults.cfm?scientific_name== Ditomyia %20euzona); the tip of the abdomen lacks a distinct genital capsule and appears to show a protruding cercal segment. Regardless of the sex of the type, the species is easily recognizable by the patterned wings and venation as it is the only Ditomyia with patterned wings known from the Nearctic region.

Based on the fasciate wings and male terminalia, D. euzona is more closely related to the Palearctic species D. fasciata Meigen than to Nearctic congeners and the two species differ primarily in differences in the shape of the hypandrium and aedeagal complex (compare Figs. 17 & 18 ) and color pattern of the scutum (three broad brown longitudinal stripes in D. fasciata and a pair of elongate brown “0”s in D. euzona ( Fig. 12 )). The type locality of D. fasciata was not given by Meigen (1818; Mamaev & Krivosheina 1988) and the concept of D. fasciata utilized here is based on a male specimen from Slovakia determined by Jan Ševčík (University of Ostrava, Czech Republic); the male terminalia of this specimen is fairly consistent with the figure of the male terminalia of D. fasciata provided by Hutson et al. (1980). However, illustrations of the male terminalia of D. fasciata sensu Zaitzev (1978, 1994 ) appear to represent a different species. Unfortunately, the syntype of D. fasciata at Museum National d’Histoire Naturelle, Paris, France is a female and therefore can’t be easily assigned to one or the other species without a broader study. Winnertz (1846) described both the male and female of D. trifasciata (considered to be a junior synonym of D. fasciata ), but Winnertz’s illustration of the male terminalia does not show the critical ventral view and many of Winnertz’s types were apparently destroyed in World War II ( Evenhuis 1997, but see Kurina & Chandler 2018). While this issue is beyond the scope of the present investigation, additional study is needed to resolve this discrepancy and clarify the identity of D. fasciata .

Distribution ( Fig. 48 ). Northeastern Nearctic. This species has also been reported from New Jersey, USA by Laffoon (1965) (not plotted on Fig. 48 ).

Figures

FIGURES 1–4. Wings. 1. D. elongata n. sp., holotype female. 2. D. euzona, male. 3. D. potomaca, female. 4. D. sohnsi n. sp., holotype male. Scale bars = ca. 1.0 mm.

FIGURES 11–12. D. euzona, male. 11. Habitus. Scale bar = ca. 1.0 mm. 12. Thorax, dorsal. Scale bar = ca. 0.5 mm.

FIGURES 13–16. D. euzona, terminalia. 13. Male, lateral. 14. Male, dorsal. 15. Male, ventral. 16. Female, lateral. Scale bars = ca. 0.25 mm. Abbreviations: ae, aedeagus; c, cerci; c1, cercus one; c2, cercus two; gc, gonocoxite; gs, gonostylus; h, hypandrium; hl, hypandrial lobe; p, paramere; s8, sternite eight; t8, tergite eight; t9, tergite nine.

FIGURES 17–18. Male terminalia, ventral, with insets showing detail of hypandrium and aedeagal complex. 17. D. fasciata (see “Remarks” under D. euzona). 18. D. euzona. Scale bars = ca. 0.25 mm.Abbreviations: ae, aedeagus; c, cerci; ea, ejaculatory apodeme; gc, gonocoxite; gs, gonostylus; h, hypandrium; hl, hypandrial lobe; p, paramere.

FIGURES 47–48. Distribution maps. 47. D. elongata n. sp. (yellow star) and D. sohnsi n. sp. (red circle). 48. D. potomaca (green circle) and D. euzona (red square); although no D. euzona specimens were examined from the District of Columbia, because D.C. is the type locality of D. euzona and is the most southern record known for the species, it has been plotted on the map.