Seri dymka (Kessel)

Cumming, Jeffrey M. & Cumming, Heather J., 2011, The flat-footed fly genus Seri Kessel & Kessel (Diptera: Platypezidae), Zootaxa 3136, pp. 61-68 : 63-66

Seri dymka (Kessel)

(Figs. 1–5)

Clythia dymka Kessel, 1961: 191 (female).

Platypeza dymka ( Kessel): Kessel, 1965 : 549. Seri dymka ( Kessel): Kessel & Kessel, 1966 : 99.

FIGURES 1–3. Habitus photographs and wing of Seri dymka Kessel. 1. female, lateral view. 2. male, lateral view. 3. wing of female (after Kessel 1987). Abbreviations: CuA+CuP—anterior + posterior branch of cubital vein, dm-m—discal medial crossvein, M1 —1st medial vein, M2 —2nd medial vein, M4 —4th medial vein, R1 —1st radial vein, R2+3 —2nd + 3rd radial vein, R4+5—4th + 5th radial vein, Sc—subcostal vein. Scale in mm.

Diagnosis. Body color (Figs. 1, 2) grey in female with slight bluish hue in some specimens (without bluish hue in female S. obscuripennis ), legs yellowish brown with tarsi more yellow (legs slightly darker in S. obscuripennis ), male black with darker legs than female; wing of female (Fig. 3) with M2 longer than apical section of M1+2 (length of M2 slightly shorter in female S. obscuripennis ); hind tarsomere 2 of female with one long anterior seta at apex; male genitalia with phallus projected only slightly beyond hypandrium ( Fig. 4 ).

Description (male). Body length 3.0 mm. Body (Fig. 2) black except reddish brown eyes; antenna dark brown to black; scutum and scutellum with bluish reflections; legs dark brown with paler tibial bases and tarsi; wing tinted brown with cell sc darker. Head with setae of occiput extended on to and covering gena; frons with 7 pairs of frontal setae; ocellar tubercle with 5 pairs of ocellar setae; antenna with postpedicel bearing long apical and ventral microtrichia, lacking seta on dorsal margin. Thorax with 3 postpronotal setae, patch of posthumeral and presutural intra-alar setae, pluriserial row of postsutural intra-alar setae, row of uniserial dorsocentral setae becoming longer posteriorly, 1 supra-alar seta, 2 strong postalar setae, 2 scutellar setae on each side. Wing venation similar to female but with M2 shorter than apical section of M1+2. Hind tarsus expanded and laterally compressed, tarsomeres 1–3 broadest, tarsomeres 1 and 2 subequal in length, tarsomere 3 narrower and longer. Abdominal segments narrowed gradually towards apex with scattered setae on tergites (longest laterally); tergite 6 with row of erect setae on apical margin. Hypopygium ( Fig. 4 ) dark brown to black with long setae on epandrium and hypandrium, surstylus with short stout setae on inner surface, hypandrium incised medioapically, phallus slender and projected slightly beyond hypandrium, sclerotized sperm pump large and multichambered with small ejaculatory apodeme, cercus and hypoproct fleshy and thinly sclerotized.

Known material. This species has been rarely, but widely, collected in North America ( Fig. 5 ). Specimens deposited in CAS were not examined. Label information for CAS specimens was taken from Kessel and Kessel (1966) and all CAS specimens were collected by them. Specimens have been collected from the following localities: CANADA: British Columbia: Stamp Falls, Vancouver Island, 13.X.1961, E.L. Kessel (2♀, CAS, CNC); Liard Hot Springs, Mile Post 496, Alaskan Highway, 2.IX.1957 (paratype ♀, CAS) and 8.VIII.1959 (1♀, CAS). Ontario: Ottawa, swept over bare path in Acer wood, 18.IX.1989, J.R. Vockeroth (1♀, CNC) and 1.X.1989, J.R. Vockeroth (1♀, CNC); Ottawa, lower Beachwood Cemetery Acer wood, aerial sweep, 23.IX.1993, J.R. Vockeroth (1♀, CNC); Renfrew, Shaw Forest, ex. old maple forest, 27.VIII.1994, P.J. Chandler (1♀, PJC); Lanark Co., Murphy’s Point Provincial Park, 44°46.05'N 76°16.31'W, ex. hardwood forest, 9.X.2010, J.M. Cumming (1♂, CNC); Bruce Co., Dunks Bay, 45° 14.98N 81° 38.45W, malaise, 10–22.IX.1996, debu 0 0 0 75053, S.A. Marshall (1♀, DEBU); Hamilton-Wentworth Co., Dundas Valley, Sherman Falls, ex. deciduous woodland, 12.IX.1994, P.J. Chandler (1♀, PJC). Yukon Territory: Alaska Highway and Morley River, 24.VII.1962 (1♀, CAS). USA: Alaska: 9 miles E of Valdez, 11–12.VII.1962, (4♀, CAS); Mosquito Lake, 27 mi N of Haines, 12.VIII.1959 (1♀, CAS) and 16.VII.1962 (1♀, CAS). California: Prairie Creek State Park, Humbolt Co., 4.XI.1960 (holotype ♀, paratype ♀, CAS); Yosemite Valley, Mariposa Co., 22.X.1960 (paratype ♀, CAS); Grizzly Creek Redwoods State Park, Humboldt Co., 21.X.1961 (1♀, CAS). Idaho: Reeder Bay, Bonner Co., 3.IX.1962 (1♀, CAS); Indian Creek State Park, 11 mi N of Coolin, Bonner Co., 3.IX.1962 (1♀, CAS); 3 mi W of Lowell, Idaho Co., 30.VIII.1962 (1♀, CAS). Maine: Mount Katahdin, Chimney Pd. trail, 25–3000’, 2.VII.1958, H.C. Huckett (1♀, CUIC). Oregon: Van Duzer Corridor, Tillamook Co., 13.IV.1963 (1♀, CAS); Loeb State Park, Curry Co., 23.IV.1962 (1♀, CAS).

Distribution. This species appears to be widely distributed in temperate forests of western North America and in northern hardwood forests of eastern North America ( Fig. 5 ). Although it is possible that the eastern and western records represent disjunct populations of S. dymka , it seems more probable that this species has a transcontinental distribution and because of its rarity has yet to be collected in intervening forested areas.

Remarks. Chandler (1974) indicated that M2 is longer in the wing of S. dymka than in S. obscuripennis when compared with the length of the preceeding section of M1+2, but this feature is apparently only diagnostic for females of each species.

A comparison of male specimens from western and eastern North America is not currently possible, because males have not yet been collected in the west and only a single male is currently known from the east. Although future comparison with western males may reveal that the eastern Nearctic specimens of Seri represent a new species, no appreciable differences have been found between female specimens from eastern and western North America.

Figures

FIGURE 4. Male genitalia of Seri dymka (Kessel), left lateral view. Abbreviations: cerc—cercus, epand—epandrium, ej apod—ejaculatory apodeme, hypd—hypandrium, hypd lb—hypandrial lobe, hyprct—hypoproct, phapod—phallapodeme, ph—phallus, spm sac—sperm sac, sur—surstylus. Scale in mm.

FIGURE 5. Known distribution of Seri dymka (Kessel). New records indicated with stars.