Sphecomyia aino (Stackelberg, 1955) Stackelberg, 1955

M. Moran, Kevin & H. Skevington, Jeffrey, 2019, Revision of world Sphecomyia Latreille (Diptera, Syrphidae), ZooKeys 836, pp. 15-79 : 22-25

Sphecomyia aino (Stackelberg, 1955) comb. n. Figs 2A, 10B, 12B, 13A, 14B, 24

Penthesilea aino Stackelberg 1955: 347. Type locality: Russia: Far East, Sakhalin Central Experimental Station. [ZISP]

Criorrhina stackelbergi Violovitsh 1973: 112. Type locality: Russia: Siberia, Altai Mts. [ZISP]

Criorhina stackelbergi Violovitsh 1976:341 - 1982: 211, 1983: 137; Peck 1988:207.

Criorrhina aino Mutin and Barkalov 1990: 118.

Criorhina aino Mutin and Barkalov 1997: 217 - Gritskevich 1998: 11; Barsukova 2012: 187 Mutin et al. 2016: 9; Mutin and Barkalov 2016: 21.

Diagnosis.

Species similar to S. pseudosphecomima or S. tsherepanovi but can be distinguished by the following characters: cell c bare on basal two-thirds; ocellar triangle pale pilose; silver-yellow pruinose; basiphallus as in Fig. 2A.

Redescription.

Male. Body length: 10.0 to 13.5 mm. Wing length: 8.2 to 8.4 mm. Head. Face silver-yellow pruinose with shiny, black, medial vitta extending from oral margin to base of antenna; frons broad, about as long as broad at antenna, two-thirds as broad at vertex as at antenna, bare, with silver-yellow pruinosity along posterior rim; vertex triangular, longer than broad, shiny, with ocellar triangle pale pilose; postocular border silver-yellow pruinose; postocular pile black; occipital pile pale; male narrowly dichoptic; antenna black, pale pilose, with length of segments roughly in a 3:3:2 ratio.

Thorax. Sub-shiny black; postpronotum pale pilose, scutum pale pilose, except with black pile posteromedially; scutellum, postalar callus, proepimeron pale pilose, posterior anepisternum pale pilose; posterior katepisternum pale pilose with broadly separated patches; anterior anepimeron, metasternum pale pilose; postpronotum, anterior eighth of scutellum, broad posterior margin of anepisternum and dorso-posterior corner of katepisternum silver-yellow pruinose; area between postpronota weakly silver-yellow pruinose, except shiny medially; anepimeron shiny; scutum without pruinose vittae; ventral calypter with long pale pile.

Legs. Foreleg black, except reddish-yellow at apex of femur; fore tarsi slightly broadened; midleg yellow, except basal four-fifths of femur and last two tarsomeres black; hind leg reddish-yellow, except last two tarsomeres black; legs pale pilose, except black pilose on fore tibia, fore tarsi, extreme apex of fore femur and last two mid and hind tarsomeres; hind coxa silver-yellow pruinose.

Wing. Hyaline; microtrichia absent from following areas: cell bc; basal two-thirds of cell c; basal fourth of cell sc; cell r1 from base almost to crossvein r-m; broad basal portion of cell br (before origin of M) and about basal two-fifths of narrower portion of this cell (caudad of spurious vein only); cell bm, except apex and narrow anterior and posterior margins of about apical fourth; broad anterior margin of cell cua; narrow, elongate, oval area proximal to vein A1.

Abdomen. Tergites and sternites shiny to sub-shiny, black with silver-yellow pruinosity as follows: tergite 1 pruinose posteriorly; tergite 2 with thin, interrupted, medial band which curves posteriorly to reach the posterolateral corners; tergite 3 with thin, medial, interrupted band which does not curve anteriorly; tergite 4 with similar but thinner band; sternite 1 weakly pruinose; sternites 2 and 3 pruinose on anterior third and sub-shiny black on remainder; sternite 4 with anteromedial pruinose spots; pile of abdomen pale.

Male genitalia. Surstylus not elongated, about as long as broad, curving upward ventrally; pilose on anterolateral outer surface of surstylus; minute spines on ventral surface and apical half of interior lateral surface; basal fourth of ventral surface of the surstylus produced into a lobe directed anteriorly, with minute pubescence on ventral and lateral inner surface; cerci rounded, with no invagination on posterior border; aedeagus as in Fig. 2A.

Female.

Similar to male except normal sexual dimorphism.

Distribution.

Far Eastern Russia including Sakhalin Island and westerly into Eastern Siberia (Fig. 24).

Biology.

Collected visiting flowers of Cornus alba (L.) Opiz, Weigela middendorffiana C. Koch, Rhododendron aureum Georgi, and Rhododendron dauricum L. Known to hilltop. Recorded flying in June and July.

Remarks.

Two morphospecies are recognized in the Sphecomyia aino complex, S. aino from continental East Palaearctic and S. tsherepanovi from the Japanese and Kuril Islands. Sphecomyia aino are silver-yellow pruinose with mostly pale pile on their an tennal segments and ocellar triangle. Sphecomyia tsherepanovi are silver-white pruinose with mostly black pile on their antennal segments and ocellar triangle. Additionally, the two populations were found to possess differently shaped dorsal horn on their basiphallus (Fig. 2A, L). We argue that these character differences, along with the 3% difference in the DNA barcode between the two taxa, especially considering that the mainland population has little to no variation in COI even across distances greater than 3000 km, are significant enough to warrant separation into two distinct species.

Of note are a male and female pair of specimens collected together in mainland Russia. Both possess characters associated with S. tsherepanovi . They are silver-white pruinose. The female is fully black pilose on its antennal segments and ocellar triangle, while the male is mixed pale and black pilose on these regions. The basiphallus of the male is identical to that of Fig. 2A. Both were barcoded, with Folmer regions identical to S. aino recovered. We consider this pair aberrant and not representative of S. aino . The male appears teneral as its exoskeleton is light brown in color. The female has a completely black pilose scutum and face along with a mixed pale and black pilose scutellum. These characters are not seen in another specimen of either species and may be indicative of a mutation. It is also is possible the female is teneral. Lending support to this hypothesis is communication with Russian Syrphidae researcher Valery Mutin who indicates all local specimens he collected fit the typical S. aino morphospecies concept. Still it is possible, though unlikely, that these specimens indicate that the mainland species is more variable than we have come to believe.