Winnertzia xylostei Mamaev, 1963

Jaschhof, Mathias & Jaschhof, Catrin, 2020, Reevaluation of species richness in Winnertzia (Diptera, Cecidomyiidae, Winnertziinae), with descriptions of 37 new species from Sweden, Peru and Australia, Zootaxa 4829 (1), pp. 1-72 : 20

Winnertzia xylostei Mamaev agg.

In our earlier study of Winnertzia ( Jaschhof & Jaschhof 2013) we came to the conclusion that W. xylostei is a species distinct from W. globifera and comprising two junior synonyms, W. iridis Mamaev and Lobowinnertzia aperta Fedotova & Sidorenko. At that time we had studied the holotype males of both W. xylostei and W. iridis (but not L. aperta ) and 25 males collected in Sweden; here we reexamined the morphology of 44 Swedish males, including those referred to in our 2013 publication. As a result, we found evidence indicating that W. xylostei sensu Jaschhof & Jaschhof (2013) comprises two species (named here A and B), possibly even a third species (C).

The species complex around W. xylostei differs from W. globifera agg. in that the gonostylus has a markedly swollen apex; the gonostylar claw is longitudinally aligned and situated dorsomedially; and the aedeagal apodeme is conspicuously long. Our Winnertzia “ xylostei A ” differs from W. “ xylostei B ” in several characters, as follows (character states of B in parentheses). The antenna, which is slightly longer than half the body, has 11 flagellomeres and fully developed translucent sensilla on flagellomeres 1–8 (antenna three fourths as long as the body, with 12 flagellomeres and fully developed translucent sensilla on flagellomeres 1–10); of the fourth flagellomere ( Figs 24–25 ), the neck is 0.5–0.7 times as long as the node, and the node is 1.6 times as long as broad (neck 0.8–0.9 times as long as the node, node 1.9 times as long as broad; Figs 28–29 ); the palpal length exceeds slightly the head height (palpus shorter than the head height); the number of pronotal setae is 11–22 (3–13); the parascutellar area is vaguely contoured (sharply contoured); the wing ( Fig. 23 ) is shorter than the body, 2.1–2.3 times as long as broad (as long as the body, 2.4–2.8 times as long as broad; Fig. 27 ); of the gonocoxal synsclerite ( Fig. 22 ), the ventral emargination is not as deep as in B, and the dorsoposterior extensions are parallel-sided with a broad, evenly rounded apex (extensions markedly convex medially and with a narrow, somewhat pointed apex; Fig. 26 ); and the gonostylus ( Fig. 22 ) has a sharp corner medially where the swollen portion transitions into the narrow base (gonostylus with smooth transition from the swollen to the narrow portion; Fig. 26 ). Winnertzia “ xylostei C ” is distinguished by 11 flagellomeres with conspicuously short necks (the neck of the fourth flagellomere is 0.4 times as long as the node), and the aedeagal apodeme whose apical portion is a long, narrow, parallel-sided tube. As regards the distributions within Sweden, species A occurs from Östergötland to Lule Lappmark, i.e. north of species B whose range comprises Småland and Öland; the single specimen we have of species C is from a forest fire site in Dalarna, central Sweden.

The xylostei complex serves to illustrate that morphological distinctions between closely related Winnertzia can be exceedingly small. Descriptions of Winnertzia in previous literature usually ignore such minute details. Similar to the situation in W. globifera agg., resolving the taxonomy of W. xylostei agg. will require a broader geographical scope and a careful review of the synonyms proposed in the past.

Material studied. Specimens listed by Jaschhof & Jaschhof (2013) and those numbered here CEC 1860– CEC 1862 (species A), CEC 3192– CEC 3212 (species B), and CEC 2939 (species C) (all in NHRS).

Figures

FIGURES 22–29. Male morphology of Winnertzia “xylostei A” (22–25) and Winnertzia “xylostei B” (26–29). 22: Genitalia, ventral, specimen from Uppland. 23: Wing, dorsal, specimen from Lule Lappmark. 24: Fourth flagellomere, lateral, specimen from Uppland. 25: Ditto, medial. 26: Genitalia, ventral, specimen from Öland. 27: Wing, dorsal, specimen from Öland. 28: Fourth flagellomere, lateral, specimen from Öland. 29: Ditto, medial. Scales for 22, 24–26 and 28–29, 0.05 mm; for 23 and 27, 0.5 mm. Arrows refer to characters described in the text.