Philetus memorandus 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 : 264-269

Philetus memorandus Melander

( Figs 4, 7 , 9–11, 13–16, 22)

Philetus memorandus Melander, 1928: 110 . Melander, 1965: 455; Poole, 1996: 158, 508; Sinclair & Cumming, 2006: 74, 98, 102–105, 107, 111, 117, 126, 139, 150, 166; Yang et al., 2007: 350; Cumming et al., 2014: 172, 210.

Type material examined. HOLOTYPE, ♂ labelled: “MtConstitution/ 22 Jul Wash”; “ TYPE / Philetus / memorandus / Mel. [mostly hand-written red label]”; “ALMelander/ Collection/ 1961” [specimen off minuten mount, glued to mostly hand-written red type label; missing mid legs (except coxae), right hind leg (except coxa) and left hind tarsus] (USNM). PARATYPES. USA. Washington: Mt. Rainier, Longmire, 18.vii.1922, A.L. Melander (1♂, USNM); Mt. Rainier, Narada Falls, 16.viii.1917, A.L. Melander (1♀, USNM); Mt. Rainier, Van Trump [Creek], 21.vii.1922, A.L. Melander (1♂, 1♀, USNM). Wyoming: Yellowst[one] Park, Canyon Camp, 12.viii.1918 [misidentified, conspecific with P. schizophorus ] (1♀, USNM).

Additional material examined. CANADA. British Columbia: Haida Gwaii, Louise Is., Skedans [ca. 52°57'57"N 131°36'59"W], 3.vii.1981, G.G.E. Scudder (1♂, UBCZ); Haida Gwaii, Laskeek Bay, Haswell Is., 10.vii.2001, 52°51'46"N 131°41'17"W, Allombert, Sylvain, HI-1SWE-1, Royal British Columbia Museum ENT001–006098 (1♂, RBCM); Mount Thornhill [ca. 54°30'42"N 128°27'12"W] nr. Terrace, 26.vii.1960, B. Heming (1♀, CNC); same data except, 3000–4000 ft., C.H. Mann (1♀, CNC); same data except, 14.vii.1960, J.G. Chillcott, second growth hemlock forest (1♀, CNC); Vancouver Is., Sproat Lake [ca. 49°16'23.61"N 125°2'30.89"W], 22.vi.1955, G.E. Shewell (1♂, CNC); Vancouver Is., Upper Carmanah Valley, 48°44'N 124°37'W, 21.vi.–3.vii.1991, T1, 32 m, N. Winchester, MT, UTM 10U, CJ 801991 (5♂, 4♀, CNC); same data except, CNC DIPTERA #103890 (1♀ barcode-associated, CNC); same data except, CNC DIPTERA #103891 (1♀ barcodeassociated, CNC); same data except, T2, 32 m (10♂, 3♀ CNC); same data except, T3, 39 m (15♂, 10♀, 1♀, CNC); same data except, CNC DIPTERA #103889 (1♀, CNC); same data except, CNC DIPTERA #103888 (1♀ barcodeassociated, CNC); same data except, T4, 33m (3♂, 1♀, CNC); same data except, 4–15.vii.1991, T1, 32 m (1♀, CNC); same data except, 16–30.vii.1991 (1♂, CNC); same data except, T2, 32 m (1♂, CNC); same data except, T2, 32 m, CNC DIPTERA #103886 (1♂ barcoded, CNC); same data except, 31.vii.–11.viii.1991, T4, 33 m (1♂, CNC). USA. California: Del Norte County: ca. 6.5 mi. NE Gasquet, nr. Cold Spring Mountain, 41°52'15"N 123°53'21"W, 31.V.2009, S.E. Brooks (1♂, CNC); Jedediah Smith Redwoods SP, Walker Rd., ca. 41°48'44"N 124°6'36"W, 25.V.2009, creek, S.E. Brooks, CNC DIPTERA #103883 (1♂ barcoded, CNC); same data except, J.M. Cumming, CNC DIPTERA #103884 (1♀ barcode-associated, CNC); same data except, 22.v.–3.vi.2009, Malaise trap, J.M. Cumming & S.E. Brooks, CNC DIPTERA #103882 (1♂ barcoded, CSCA); same data except, CNC DIPTERA #’s 103892, 103893, 103895, 103896 (4♀ barcode-associated, CNC, CSCA); West Fork of Patrick Crk, 41°55'03"N 123°51'28"W, 31.V.2009, J.M. Cumming (1♂, CNC); same data except, 24–31.v.2009, Malaise trap, J.M. Cumming & S.E. Brooks (2♂, 3♀, CNC); Humboldt County: ca. 7 miles SE Orick, Lost Man Creek trail, 41°15'53"N 123°59'16"W, 2.vi.2009, J.M. Cumming (1♂, CNC); same data except, J.M. Cumming, CNC DIPTERA #103887 (1♀ barcode-associated, CNC); same data except, S.E Brooks, CNC DIPTERA #103885 (1♀ barcode-associated, CNC). Oregon: Benton County: 5 mi. up Woods Crk Rd from jct. Hwy 20, riparian woods on creek edge, 30.v.–24.vi.2014, ca. 44.544022, -123.503047, MT014, S. Fitzgerald, JSS #43838 (1♀, barcodeassociated, CNC); same data except, 6.4 mi. up Woods Crk Rd, across old road fir/alder/maple, 24.vi.–14vii.2014, MT018 (1♀, CNC); Mary’s Peak, upper Parker Creek, nr. cmpgrd, 44.5087°N 123.5583°W, 6.vi.–4.vii.2014, along creek, S. Fitzgerald (2♂, 1♀, CNC); Curry County: Siskiyou National Forest, nr. Elko Cmpgrd, 2500 ft., 42°23'07"N 124°13'44"W, 2.vi.2009, G. Courtney (2♂, 1♀, CNC; 2♂, ISIC); Lane County: Siuslaw Nat. For., 3 mi. S Yachats [ca. 44°16'N 124°6'W], 15.vii.1989, streams along Gwynn Crk Trail, B.J. Sinclair (1♂, CNC). Washington: Pacific County: Ft. Canby SP [ca. 46°16'N 124°04'W], nr. Ilwaco, 13–15.vi.1973, W.J. Turner (1♂, WJTC); Ilwaco [ca. 46°16'N 124°04'W], 12.vii.1922, A.L. Melander (1♀, USNM); Pierce County: Mt. Rainier NP, Comet Falls trail, 46°46.724'N 121°47.029'W, 16.vii.2012, 1090– 1360 m, B.J. Sinclair (1♂, CNC); same data except, 46°47.499'N 121°46.930'W, 3.vii.2013, 1200–1450 m (4♂, 2♀, CNC); Longmire [ca. 46°44'59"N 121°48'45"W], 27.vi.1935, A.L. Melander (1♂, USNM); same data except, 20.vii.1922 (1♀, USNM); Narada Falls to Cougar Rock, 46°46.313'N 121°44.949'W, 6.vii.2013, B.J. Sinclair (1♂, CNC); Narada Falls to Reflection Lk. trail, 46°46'N 121°44'W, 1400 m, 17.vii.2012, B.J. Sinclair (1♀, CNC); Reflection Lk. to Narada Falls, 46°46.162'N 121°44.320'W, 17.vii.2012, snow patches, B.J. Sinclair (4♂, 1♀, CNC); Van Trump Crk, above Christine Falls [ca. 46°46'51"N 121°46'47"W], 3900 ft., 11.viii.1977, W.J. Turner (1♀, WJTC).

Diagnosis. Philetus memorandus is characterized by male terminalia (Figs 11, 13–16) with elongate cercus connected to wide medial subepandrial lobe and lengthened ventral subepandrial lobe with broad deflexed apex, large epandrial lobe with dorsal process and rounded apex, hypandrium with long hook-shaped apical rods above dorsally prolonged median apical process, postgonite projected dorsally as wide rounded lobe, and tubular phallus with partially desclerotized broadly expanded apex. The longer, more narrowly produced apex of the antennal postpedicel ( Fig. 7 ) in both sexes separates most specimens from those of P. schizophorus .

Redescription. Male. Body length 3.0– 4.5 mm, dark brownish grey, covered with silvery grey tomentum. Antenna dark brown to black; postpedicel pyriform with apex narrowly produced towards stylus ( Fig. 7 ). Legs brown to greyish brown. Wing hyaline with brownish veins. Halter brownish white. Terminalia (Figs 11, 13–16): hypandrium with long hook-shaped apical rods arising above base of long dorsally directed median apical process; postgonite projected dorsally as wide rounded lobe; phallus tubular, apex partially desclerotized and broadly expanded; epandrial lobe large with bifid dorsal process and rounded apex, apical surface covered with minute setulae; ventral subepandrial lobe lengthened with broad deflexed apex; medial subepandrial lobe wide, connected basally to both ventral subepandrial lobe and cercus, with short spine-like setulae along apical margin; cercus elongate, rounded apically with pronounced ventral hook.

Female. Body length 3.5–5.0 mm. Similar to male. Female terminalia (Fig. 10) partially telescopic; tergite 10 short; cercus approximately 3X as long as wide. Nearly indistinguishable from female of P. schizophorus except for the longer, more narrowly produced apex of the antennal postpedicel in most specimens ( Fig. 7 ).

Geographical distribution and seasonal occurrence ( Fig. 22 ). Known from the montane and coastal forests of western North America from British Columbia, Washington and Oregon, south to northern California. Adults have been collected from the end of May until the middle of August.

FIGURES 9−12. Philetus morphology. 9. P. memorandus , wing. 10. P. memorandus , female terminalia, dorsal view; from Sinclair & Cumming (2006, fig. 208). 11. P. memorandus , male terminalia, lateral view. 12. P. schizophorus , male terminalia, lateral view. Abbreviations: an lb—anal lobe; bm-m—basal medial crossvein; cerc—cercus; CuA—anterior branch of cubital vein; cua—anterior cubital cell; CuP—posterior branch of cubital vein; dm—discal medial cell; dm-m—discal medial crossvein; gen fk—genital fork; M1, M2, M4—medial veins; R1, R2+3, R4, R5—radial veins; Sc—subcostal vein; spmthspermatheca; tg—tergite.

Remarks. Female specimens collected from the same localities as males of P. memorandus , at or around the same seasonal date, were generally assumed to be conspecific with associated males. In addition, the identity of a number of female specimens of P. memorandus was confirmed by comparing COI mitochondrial DNA barcode sequences (with length = 657–658 bp) from males and females that clustered together with <2% genetic divergence ( Fig. 24 ). Male and female specimens with shorter sequence lengths (264–342 bp) also clustered with P. memorandus ( Table 1 ); two specimens (326 and 342 bp) clustered with <2% genetic divergence and seven specimens (264–307 bp) clustered with P. memorandus at approximately 4% genetic divergence. Female specimens with these shorter sequence lengths ( Table 1 ) were additionally considered to be conspecific with P.

memorandus based on this barcode sequence data. Subsequent examination of these identified females in conjunction with males also revealed a subtle difference in the shape of the apex of the antennal postpedicel in most specimens of P. memorandus ( Fig. 7 ), when compared with the postpedicel of most specimens of P. schizophorus ( Fig. 8 ).

Philetus memorandus has been collected more often than P. schizophorus , but is still only taken infrequently. However, one large series of male and female specimens was collected in the canopy of a coastal wet temperate rainforest ( Fig. 3 ) on Vancouver Island, British Columbia (see Marshall & Winchester 1999). The specimens were all collected in Malaise traps placed more than 30 metres above the forest floor ( Fig. 2 ), but were not taken in traps placed at ground level. This may indicate that the rarity associated with Philetus could actually be due to adults being active high in the canopy of coastal and montane forests, rather than to low abundance levels.

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.

FIGURES 1 − 3. Philetus habitus photograph and habitat. 1. Philetus sp., live female; photograph by S. A. Marshall. 2. Sitka spruce canopy, Upper Carmanah Valley, Vancouver Island, British Columbia. 3. Coastal wet temperate rainforest, Upper Carmanah Valley.