Mesembrina decipiens Loew 1873

Mesembrina decipiens Loew, 1873

Figs. 1 A, 1D, 1G, 2A–D, 3A–B

Mesembrina decipiens Loew, 1873: 239.

Mesembrina putziloi Portschinsky, 1873: 57.

Hyperdermodes solitaria Knab, 1914: 325, syn. nov.

Diagnosis: Large species resembling a bumble bee (Fig. 1 A). Gena dusted brownish. Thorax and abdomen with numerous yellow bristles (Fig. 1 A), no dusted white lines on prescutum. Wing base and calypters intensely yellow, M1 vein ending past wing apex (Fig. 1 D). T2 of males curved and elongated with row of fine pv setae increasing in lenght towards apex (Fig. 1 G).

Type material examined: Mesembrina decipiens – Holotype ɗ labeled “Baical VI / Kultuk 61”; “Coll. / H. Loew”; “ Type ”; “ Mesembrina / decipiens / Lw.”; “ Holotype Ψ / Mesembrina / decipiens / Conf. A. C. Pont 1999”; “Zool. Mus. / Berlin” (ZMHU).

Hyperdermodes solitaria – Holotype Ψ labeled “High Isl / Alberta”; “T. Baird / Hyth River / Alta”; “ Type / No. 18415 / U.S. N.M.”; “Hyperdermodes / solitarius / Knab” (USNM).

The female holotype of M. putziloi, from Irkutsk, Russia is in the Zoological Institute of the Russian Academy of Sciences, St. Petersburg, Russia. This specimen was recently examined by Pont (2004) who confirmed its status as a junior synonym of M. decipiens.

Other material examined: 16 ɗ, 54 Ψ: NEARCTIC: Canada: Alberta: Banff, Bilby, Cypress Hills, Edmonton, Kananaskis Lakes, Lake Louise, Nojack, Slave Lake, Waterton Lakes Nat. Pk.; British Columbia: Aspen Grove, Kamloops, Penticton, Salmon Arm, Trinity Valley; Manitoba: Erikson; Ontario: Lake Nipigon; Yukon: Dawson, Dempster Hwy., La Force Lake, West Dawson; USA: Alaska: Homer, Isabel Pass, Matanuska, Palmer; Colorado: Culebra Mts., Mt. Evans, Pingree Park, Sierra Blanca; Michigan: Isle Royale; Montana: Pipestone Pass; North Carolina: Great Smoky Mts. Nat. Pk.; Washington: Mt. Bonaparte; PALAEARCTIC: China: Jilin: Hani; Mongolia: Tunkun; Russia: Sibirskiy: Kargasok, Trans-Baikal; (JBWM, CNC, BMNH, USNM, UZMH).

Description: Male: body length 11.3–14.3mm

Head: Background color black, parafacial dusted brownish-yellow to silvery, gena brown pruinose; eye sparsely haired; distance between eyes 1.0x–1.3x distance between the outer margins of the posterior ocelli; frons with 8–10 fine black medioclinate fr and with abundant weaker medioclinate, proclinate or reclinate orb, tuft of short black setae posterior to ocellar triangle, 1 i vt and 2 convergent pavt; palpus orange, 5.0x as long as wide; pedicel orange, haired and with 2 setae, more than 2x length of others; first flagellomere 4.0x as long as wide, color orange-reddish at base turning brownish towards apex; basal half of arista thickened and always yellow; prementum haired and glossy, 2.0–2.5x as long as wide.

Thorax: Glossy black; covered in fine hairs, black hairs and setae found throughout, dense yellow hairs usually present on prescutum, postpronotum, scutum and often on the scutellum, these sometimes also extending down onto the anepisternum but very rarely extending onto the katepisternum; anepimeron haired with a tuft of longer hairs on dorsal edge; dorsal thoracic bristles black or yellow and often nearly indistinguishable from surrounding hairs, 0 + 1–2 acr, 1–2 + 2–4 dc, 1 + 1 ial, 1 + 5–7 spal, 3 npl, 2 pal; anepisternum bare anteriorly; 0–1 a kepst, 1 p kepst; postpronotum haired, with 2–3 strong ppnl, at least one usually yellow; scutellum glossy black, scutellar setae black or yellow, 1 pair of apical sctl, 6–8 pairs of lateral sctl.

Legs: Mostly black, fifth tarsomere yellowish and flattened on all legs; pulvilli large, 2.0x as long as wide, claws with a black tip and a bright yellow base; F1 with 1 row of equal pd on basal two-thirds, 1 row of p decreasing in size from base and 1 complete row of sub-equal v; F2 with 3–5 p in a group near apex; F3 with 1 row of sub-equal ad and av, apical third of ad and av rows stronger than basal sections; T1 with very fine and short a giving the surface a shiny brown look, 1 strong ad near apex and 1 row of d increasing in length towards apex; T2 (Fig. 1 G) elongated and noticeably curved towards apex, with 1 row of 7–8 strong p subequally spaced, 1 row of fine brown pv increasing in length apically but of equal length on apical third and 1 row of equal v eventually converging with pv; T3 with 1 long pd near midpoint; fore tarsomeres: 1>2>3>4<5, with distinct ventral yellow line extending from the midpoint of tarsomere 1 to apex of tarsomere 5; mid tarsomeres: 1>2>3>4<5, usually without distinct ventral yellow line extending from the midpoint of tarsomere 1 to apex of tarsomere 5 but if line present then usually dull yellow; hind tarsomeres: 1>2>3>4<5, with very fine brown and short p giving a shiny look, with or without distinct ventral yellow line.

Wing: (Fig. 1 D). Mostly clear with heavy yellow tinge on basal half, apical half occasionally with brown tinge surrounding veins; wing veins yellow on basal half and brown on apical half; basicosta brownish-black; wing veins yellow on basal half, brown on apical half; M1 vein running parallel to wing margin on apical quarter of wing and ending slightly past wing apex; alula yellowish; calypters yellow.

jection longer than inner projection (Fig. 2 B), outer projection with small but sharp tooth-like apical protrusion (Fig. 2 A, 2B); surstylus short, bent medially with apex ending abruptly with a straight edge in posterior view (Fig. 2 B), concave posteriorly in lateral view (Fig. 2 A); pregonite with base wide and apex slender, with 3–4 lateral setae (Fig. 2 C); postgonite with base slightly concave with several small lateral setae and apex rounded, 2.0x as high as width of base (Fig. 2 C); epiphallus as long or slightly shorter than phallapodeme and with apex forked (Fig. 2 C); apex of phallapodeme bulb-shaped (Fig. 2 C); ejaculatory apodeme well sclerotized and beak-like in appearance (Fig. 2 C); lateral sclerites of distiphallus broad and weakly sclerotized, apical section of lateral sclerites with sparse spinules (Fig. 2 C).

Female: body length 11.1–17.0mm. Differs from male as follows:

Head: Distance between eyes 5.0x distance between the outer margins of the posterior ocelli, tuft of short setae posterior to ocellar triangle usually yellow but sometimes black, frontal vitta reddish-brown, sometimes fine frontal setae present on vitta, parafacial brownish-yellow;10–17 medioclinate fr, stronger anteriorly and usually yellow but sometimes black, usually 2 strong proclinate orb located medially and 2 strong reclinate orb located posteriorly on head, surrounded by fine yellow or black proclinate orb 0.5x the length of larger orb and not extending onto the parafacial.

Thorax: Usually with higher density of yellow hairs on thorax than in male, scutellum with yellow hairs always present, lateral sctl yellow or black.

Legs: T2 not curved and of normal length with 1–2 ad on basal half, 2 pd on basal half and 3 pv on basal two-thirds, T3 with 1 long d near apex; fore tarsomeres with or without distinct ventral yellow line extending from the midpoint of tarsomere 1 to apex of tarsomere 5 but if present, then line dull yellow, mid and hind tarsomeres without ventral yellow line.

Wing: As in male.

Abdomen: As in male.

Postabdomen: Anterior portion of tergite 8 split longitudinally into 2 rectangular parallel rods, posterior plate of tergite 8 with 6–7 robust sub-equal setae (Fig 3 A); anterior portion of sternite 8 split longitudinally into 2 club-shaped parallel plates, posterior plate of sternite 8 with 4–6 robust sub-equal setae (Fig 3 B); tergite 10 bare except for 2 pairs of strong setae on the posterior margin (Fig 3 A); cercus bare, cercal pegs small (Fig. 3 A, 3B); spermathecae 2.0x as long as wide. (Fig. 3 C).

Distribution: NEARCTIC: Canada: Alberta, British Columbia, Manitoba, Northwest Territories, Ontario,Yukon; USA: Alaska, Colorado, Idaho, Michigan, Minnesota, Montana, North Carolina, Washington. PALAEARCTIC: China, Korea, Mongolia, Russia east of the Ural Mts.

Remarks: The possibility that the Nearctic M. solitaria could be a synonym of the Palaearctic M. decipiens was hinted at by both Hennig (1963) and Pont (pers. comm.), but these suspicions were never formalized. The features used in the literature (Knab 1914; Hennig 1963) to traditionally separate these two species were: males of M. decipiens with dense yellow hairs on the scutellum, whereas these hairs are dark in M. solitaria; females of M. decipiens with yellow setae extending down onto the katepisternum, whereas in M. solitaria the katepisternal setae are dark. After examination of all available material of M. solitaria and M. decipiens (including holotypes), specimens with intermediate features as well as both extremes of the variability spectrum were found in the Nearctic and the Palaearctic regions and therefore these characters appear to be variable. Consequently, we believe that the two nominal species are the same and M. solitaria is therefore a junior synonym of M. decipiens. This synonymy makes M. decipiens the first Mesembrina species with a confirmed Holarctic distribution.