Isocolpodia unidentata (Marikovskij) Jaschhof & Jaschhof, 2020

Jaschhof, Mathias & Jaschhof, Catrin, 2020, The Porricondylini (Diptera: Cecidomyiidae: Porricondylinae) of Sweden revisited: descriptions of nineteen new species of ten genera, including a new genus, Zootaxa 4728 (2), pp. 151-182 : 178-180

Isocolpodia unidentata (Marikovskij) , new combination

Figs 50–52

This poorly known species was described by Marikovskij (1958) as a Holoneurus on the basis of a single male from Kazakhstan. His illustrations of the genitalia (figs 2a–b), although sketchy, suggest that a male porricondyline in our material from southeast Sweden is conspecific. We have not yet seen the holotype of H. unidentatus for corroborating our identification, though. The last to study that specimen (which should be deposited in Marikovskij’s collection in Alma-Ata, Kazakhstan) were apparently Mamaev & Zaitzev (1998), who concluded that H. unidentatus is a species of Stomatocolpodia Mamaev ; arguments explaining this decision were not provided. In our opinion H. unidentatus is misplaced in both Holoneurus and Stomatocolpodia ( Jaschhof & Jaschhof 2013: 295) . Holoneurus must be ruled out as an appropriate placement because males in that genus have fewer than 14 flagellomeres and no basitarsal spines, whereas Stomatocolpodia is distinguished by twisted, somewhat corkscrew-shaped parameres ( Jaschhof & Jaschhof 2013). For the time being, we think the best possible solution is to place Marikovskij’s species in the genus Isocolpodia Parnell. Males of Isocolpodia have 14 flagellomeres, basitarsal spines, a single gonostylar tooth, and no gonocoxal processes, which all are character states found in H. unidentatus ( Figs 50–52 ). The type species of Isocolpodia , Porricondyla graminis Felt , is peculiar for the medial gonocoxal bridges being strongly sclerotized ( Jaschhof & Jaschhof 2013: 294), which is another feature found similarly in H. unidentatus . As a shred of doubt whether H. unidentatus is appropriately classified with Isocolpodia , the parameres and / or the aedeagal apodeme are usually bifid in that genus ( Jaschhof & Jaschhof 2013: 294), while both these structures are undivided in the species in question ( Fig. 52 ). We interpret this as a result of secondary simplification. Fedotova & Sidorenko (2007b) classified H. unidentatus in Avicolpodia Fedotova & Sidorenko , in their view a subgenus of Stomatocolpodia but in our opinion a synonym of Isocolpodia ( Jaschhof & Jaschhof 2013: 292) . Since we had not seen specimens of H. unidentatus prior to the present study, we retained this species in Stomatocolpodia in our 2013 paper.

Diagnosis. Most of the character states found in male I. unidentata correspond with what we regard as typical of the genus Isocolpodia ( Jaschhof & Jaschhof 2013: 293 f.), with the exception of the parameres that in I. unidentata are tusk-shaped, not bifid ( Fig. 52 , ↓ 1). The parameral apices are bent dorsad, a detail hard to see in specimens mounted with the ventral side up (note that both Marikovskij (1958) and Fedotova & Sidorenko (2007b) described the parameres as straight). The gonostylus, which in ventral view looks slender and moderately convex ( Fig. 52 ), is in fact dorsoventrally flattened, with the gonostylar apex bearing a long, nose-shaped tooth (↓ 2). The U-shaped gonocoxal emargination is reinforced by sclerotization, and the aedeagal apodeme is a thin, moderately sclerotized rod almost as long as the gonocoxae ( Fig. 52 ). Other relevant characters are the short eye bridge, which is only 1–2 ommatidia long dorsally; the 4-segmented palpus, which is slightly shorter than the head height; the setose antepronotum; the short, slightly bent basitarsal spines ( Fig. 50 ); and the long, narrow wing (length / width ratio 3.8). Vein M 1+2 is absent; M 4 is short, weak, and declining both apically and basally; and the basal half portion of the membrane is largely devoid of setae.

Material studied. Sweden: 1 male, Öland , Mörbylånga, St. Dalby lund NR, mixed broadleaf forest with abundant dead ash trees, 9 August–3 October 2015, MT, MCJ (spn. CEC 2553 in NHRS) .

Figures

FIGURES 50–55. Male morphology of Isocolpodia unidentata (50–52) and Zaitzeviola dubitabila (53–55), specimens from Sweden. 50: Basitarsus of foreleg, lateral. 51: Fourth flagellomere, lateral. 52: Genitalia, ventral. 53: Genitalia, ventral. 54: Parameres and aedeagal apodeme, ventral. 55: Fourth flagellomere, lateral. Scales 0.05 mm. Arrows refer to characters described in the diagnoses.