Philetus schizophorus Melander

Cumming, Jeffrey M., Brooks, Scott E. & Sinclair, Bradley J., 2016, Review of the little-known western Nearctic fly genus Philetus Melander (Diptera: Empididae), with a discussion of its phylogenetic assignment, Zootaxa 4093 (2), pp. 261-274 : 269-271

Philetus schizophorus Melander

( Figs 5, 6, 8 , 12, 17–20, 23)

Philetus schizophorus Melander, 1928: 110 . Melander, 1965: 455; Poole, 1996: 158, 563; Yang et al., 2007: 350.

Type material examined. LECTOTYPE (here designated in order to fix identity of the species), ♂ labelled: “Mt.RainierWn/ VanTrump Crk [above Christine Falls]/ Sept. 1, 1917 / A.L.Melander”; “ TYPE / Philetus / schizophorus / Mel. [mostly hand-written red label]”; “ALMelander/ Collection/ 1961”; “ LECTOTYPE / Philetus / schizophorus Melander / des. Cumming, Brooks &/ Sinclair 2016 [red label]” [left hind leg glued to minuten mount] (USNM). PARALECTOTYPE. Same locality and date as lectotype [but indicated as paratype on mostly hand-written red label] (1♂, USNM). Our paralectotype label has additionally been attached to this specimen.

Additional material examined. CANADA. British Columbia: Glacier National Park, Illecillewaet trail from Cmpgrd, 20.vii.2012, 1320 m, 51°16.018'N 117°29.799'W, B.J. Sinclair (1♀, CNC); same data except, JSS #43836 (1♀ barcode-associated, CNC). USA. Alaska: Matanuska-Susitna Borough: Fern Mine [61°49'31"N 149°14'25"W], 27.vii.1956, WCF (1♂, WSU). Arizona: Apache County: White Mts., Coulter Ranch, 28.vi.1947, 9200 ft., John L. Sperry (1♂, USNM). Colorado: Lake County: Fremont Pass, Climax [ca. 39°18'5.26"N 106°15'44.46"W], 11318 ft., 19.viii.1983, P. Arnaud, Jr., at flr. Achillea , JSS #43837 (1♀, CAS); Larimer County: Pinewood Springs, MT in woods along sm. crk, 40.269476°N 105.360503°S, 7.ix.–12.x.2014, MT039, S. & B. Fitzgerald, JSS #43839 (1♂ barcoded, CNC). Montana: Flathead County: Glacier National Park: 1 mi. NW Logan Pass [ca. 51°16'N 117°29'W], 6500 ft., stream, 18.viii.1969, E.M. Fisher (1♀, CAS). Nevada: Elko County: 12 mi. S Wells, Angel Lake [ca. 41°1'35"N 115°5'7.42"W], 11.vii.1961, J.G. Chillcott (1♂, CNC). Oregon: Hood River County: Starvation Creek State Park, at falls [ca. 45°41'14"N 121°41'18"W], 26.vi.1978, D.D. Wilder (1♀, CAS). Washington: Pierce County: Mt. Rainier NP, West End Rd., 3 mi. N jct. Hwy 706 on Tahoma R., 2500 ft., 12.viii.1977, sweeping, W.J. Turner (1♂, WJTC); Yakima County: White Pass [46°38'19"N 121°23'22"W], Leech Lake, 4500 ft., 15.vii.1983, 1578/1/30 -, J.A. Downes, CNC DIPTERA # 103881 (1♂, CNC). Wyoming: Yellowstone Park, Canyon Camp, 12.viii.1918 (1♀, USNM, see “ Type material examined” under P. memorandus ).

Diagnosis. Philetus schizophorus is characterized by male terminalia (Figs 12, 17–20) with elongate apically bifid male cercus connected to narrow rounded medial subepandrial lobe and long apically expanded ventral subepandrial lobe, small truncate epandrial lobe, hypandrium without apical rods, with thin short median apical hypandrial process, postgonite projected dorsally as broad U-shaped lobe, and dorsally directed phallus with unexpanded partially desclerotized apex. The shorter, more broadly produced apex of the antennal postpedicel ( Fig. 8 ) in both sexes separates most specimens from those of P. memorandus .

Redescription. Male. Body length 3.0–4.0 mm, dark brownish grey, covered with silvery grey tomentum. Antenna dark brown to black; postpedicel pyriform with apex broadly produced towards stylus ( Fig. 8 ). Legs brown to greyish brown. Wing hyaline with brownish veins. Halter brownish white. Terminalia (Figs 12, 17–20): hypandrium without apical rods arising above base of thin short median apical process; postgonite projected dorsally as broad U-shaped lobe, basal portion with minute setulae; phallus tubular, directed dorsally near midpoint adjacent pair of ventral medial teeth, apex partially desclerotized and not expanded; epandrial lobe small, truncate, with some minute setulae; ventral subepandrial lobe long, expanded apically along dorsal margin; medial subepandrial lobe narrow, apically rounded, connected basally to cercus, without short spine-like setulae along apical margin; cercus elongate, bifid apically with long pointed dorsal lobe and club-shaped ventral lobe.

Female. Body length 3.5–4.0 mm. Similar to male except for female terminalia. Nearly indistinguishable from female of P. memorandus except for the shorter, more broadly produced apex of the antennal postpedicel in most specimens ( Fig. 8 ).

Geographical distribution and seasonal occurrence ( Fig. 23 ). Known from the montane and coastal forests of western North America from Alaska south to Arizona, including records from British Columbia, Washington, Oregon, Montana, Wyoming, Nevada and Colorado. Adults have been collected from late June until the middle of October.

Remarks. Two COI mitochondrial DNA barcode sequences (with length = 658 bp) were obtained from a single male and female of P. schizophorus ( Table 1 ), which clustered together with <2% genetic divergence ( Fig. 24 ). This confirms the species identity of the female specimen, as well as a second associated female taken during the same collecting event (listed above under “Additional material examined”). Philetus schizophorus has rarely been collected and until now the female has remained unknown. Subsequent examination of these two identified females in conjunction with males, also revealed a very subtle difference in the shape of the apex of the antennal postpedicel in most specimens of both species (compare Figs 7 and 8 ), allowing for the recognition of additional specimens of P. schizophorus .

The distribution of P. schizophorus while overlapping with P. memorandus in Washington and Oregon, seems more widespread, extending northward to Alaska, and eastward into Nevada, Arizona, and along the Rocky Mountains of British Columbia, Montana, Wyoming, and Colorado. The seasonal records also appear to stretch into the fall compared with those of P. memorandus (i.e., until the middle of October rather than the middle of August).

Figures

FIGURE 24. Neighbour-joining tree of seven Philetus specimens and three outgroup specimens with COI sequences of> 450 base pairs (bp).

FIGURES 4 − 8. Philetus morphology. 4. P. memorandus, pinned male. 5. P. schizophorus, male head, lateral view. 6. P. schizophorus, male head, anterior view. 7. P. memorandus, female antenna. 8. P. schizophorus, female antenna. Abbreviation: pped—postpedicel.

FIGURES 21 − 23. Distribution of Philetus. 21. Overall distribution of the genus Philetus, including undetermined female specimens. 22. Known distribution of P. memorandus. 23. Known distribution of P. schizophorus.