Empis (Enoplempis) aerobatica Melander

Sinclair, Bradley J., Brooks, Scott E. & Cumming, Jeffrey M., 2025, Revision of the western Nearctic species of Empis subgenus Enoplempis (Diptera: Empididae), Zootaxa 5615 (1), pp. 1-200 : 21-23

Empis (Enoplempis) aerobatica Melander

( Figs 7, 8 , 41–45 , 52 , 54 )

Empis aerobatica Melander, 1902: 323 . Type locality: Idaho, USA.

E. (Enoplempis) aerobatica : Melander, 1928: 142 (assigned to subgenus Enoplempis ).

Empis aerobatica : Melander, 1965: 458 (catalogue); Yang et al., 2007: 130 (catalogue).

Type material examined. LECTOTYPE (here designated in order to fix identity of the species) ♂, labelled: “ Moscow [46°48ʹN 116°52ʹW]/ Idaho ”; “ JM Aldrich/ Coll”; “Cotype/ No. 41825/ U.S.N.M. [red label]”; “ June 17/ 1899 ”; “ Empis / aerobatica/ Mel.”; “ LECTOTYPE / Empis aerobatica Melander / des. Sinclair, Brooks &/ Cumming 2025 [red label]” [♂ lectotype, ♀ paralectotype, mounted as pair with chloropid prey on balloon] ( USNM) . PARALECTOTYPES: USA. California: Kern County: (1♀, USNM) [= E. bigoti ]. S. California (1♂, CUIC) [= E. bigoti ] . Idaho: Same data as lectotype (5♂, 2♀, USNM) .

Notes on type specimens. Melander (1902) stated that this species was based on seven males and four females from California and Idaho. The Idaho specimens are exemplars from the balloon-making flies reported in Aldrich & Turley (1899). The single male and female from California were misidentified and represent E. bigoti .

Additional material examined. USA. Idaho: Latah County: Bovill [46°51′N 116°23′W], 17.vi.1911 (1♂, USNM) ; same data except, 18.vi.1911 (1♂, USNM) ; 3 mi. S Helmer [46°48ʹN 116°28ʹW], 22.v.1971, WJT (2♂, 1♀, WSU) ; same data except, nr L. Boulder Cpgd, Potlatch R, 25.v.1986, 2600 ft (3♂, WSU) ; same data except, 6.vi.1987 (1♀, WSU) ; same data except, 24.v.1985, Amelanchier (4♂, 1♀, WSU) ; same data except, swarm (5♂, 5♀ mounted as pairs with Chloropidae , Psyllidae, Chalcidoidea and Ceratopogonidae prey on balloons, WSU; 2♂, 1♀, WSU) ; Potlatch R, 3 mi. S Helmer, nr Lk. Boulder Cpgd [46°48ʹN 116°28ʹW], 2600–2800 ft, 29.v.1991, S.D. Gaimari (1♂, 3♀, CNC; 2♂, 3♀, CSCA) ; same data except, 15.vi.1991, P. McLelland (1♂, CSUC) ; Lost Ck , 12 mi. ENE Potlatch [46°57′N 116°41′W], 2700 ft, 13.v.1980, Amelanchier fls (3♂, 3♀, WSU) ; same data except, 1.vii.1980, MT (1♀, WSU) ; same data except, 1–3.vii.1980 (1♀, WSU) ; Moscow [46.73°N 117.00°W] (2♂, USNM) ; 6 mi. NE Moscow , 29.vi.1975, JAP (1♀, EMEC) ; 7 mi. NNE Moscow , 2700 ft, 29.vi.1975, WJT (1♂, WSU) ; Moscow Mtn [46°48ʹN 116°52ʹW], 23.vi.1952, E.I. Schlinger [1♂, UCDC] ; same data except, 3.vii.1968, WFB (1♂, WFBM) ; same data except, 27.vi.1962, 3000 ft, A.P. Gupta (1♀, WFBM) ; Moscow Mtn, Moscow Mtn Rd, 46°47.721ʹN 116°54.093ʹW, 1000 m, 22.vi.2014, cascading str., BJS (3♂, CNC) ; Strychnine Ck nr Laird Pk [46°56′N 116°38′W], 15 mi. ENE Potlatch, 2900 ft, 22.vi.1979, WJT (8♂, 7♀, WFBM) ; same data except, 1.vii.1980, Physocarpus (11♂, 5♀, WSU) ; Troy, Hwy 8 at mm 15 W Fk Ck, 747 m, 46.733°N 116.757°W, 9.vi.2009, E09-62a, I.S. Winkler (1♂, CNC) . Nez Perce County: Lenore [46°30′N, 116°3′W], 10.v.1959, WFB (1♂, WFBM) ; Spalding [46°26′N 116°49′W], 19.v.1961, WFB (1♂, WFBM) ; Waha [46°12′N 116°51′W], 18.vi.1909 (1♀, 2 pinned balloons with Cecidomyiidae prey, USNM) . Shoshone County: Rd 50 E Calder , 690 m, St. Joe NF, Huckleberry Cpgd , 47°15.953′N 116°5.449′W, 20.vi.2014, ex roadside str., BJS (1♀, CNC) . Oregon: Baker County: U. Goose Ck , 34 mi. SE Union [44°56′N 117°25′W], 4160 ft, 24–25.vi.1977, sweeping Anaphalis flowers, WJT (3♀, WSU) ; Velvet Ck [45°1′N 117°31′W], 28 mi. SE Union, 4720 ft, Wallowa-Whitman NF, 17.vi.1977, sweeping, WJT (1♂, WSU) . Wallowa County: Minam SP [45°47′N 117°43′W], 9.vi.1971, WJT (3♂, 1♀, WSU) . Washington: Asotin County: Fields Spring SP [46°4′N 117°10′W], 27.vi.1972, W.B. Garnett (1♂, WSU) ; same data except, 4 mi. S Anatone , 7.vi.1973, 3500–4000 ft, MT, D. Corredor (1♂, WSU) ; same data except, 12–13.vi.1974, MT with dry ice, WJT (1♀, WSU) ; same data except, 26.vi.1974 (1♂, WSU) . Columbia County: Tucannon Fish Hatch. , 20 mi. E Dayton [46°19′N 117°39′W], 2650 ft, 12.v.1979, sweeping, WJT (2♂, 1♀, WSU) . Spokane County: Valleyford [47°31′N 117°14′W], 19.vi.1919, ALM (1♂, USNM) . Whitman County: 8 mi. SW Pullman, Lyle Grove Biol. Area [46°43ʹN 117°11ʹW], 2100 ft, 26.v.1979, MT, WJT (1♂, WSU) ; same data except, 30.v.1979, S. Woods (1♂, WSU) ; same data except, 4.vi.1979 (2♀, WSU) ; same data except, 4–6.vi.1979 (1♂, WSU) ; same data except, 6.vi.1979 (2♂, WSU) ; same data except, 6–8.vi.1979 (1♂, WSU) ; same data except, 20–22.vi.1979 (1♀, WSU) ; Union Flat [46°34′N 117°8′W], 16.vi.1916 (2♂, USNM) ; same data except, 3.vi.1918 (1♂, USNM) . Yakima County: 4 km NW Cliffdell, Sawmill Flat Cpgd, between Naches R and Hwy 410, 46°58′25″N 121°05′46″W, 785 m, 19.vi.2005, sweep, C.J. Borkent, CJB05-21 (1♂, LEM) .

Diagnosis. This species is distinguished from other species of the E. (En.) bigoti species group by narrow, shiny anterior and posterior bands on the abdominal tergites in both sexes ( Figs 41, 45 ), male hind femur with median inflated ventral lobe oval and distinct ( Fig. 44 ), upper section of phallus strongly bent and tapered, and basal section of phallus not projecting beyond base of upper section.

Redescription. Wing length 4.7–5.6 mm. Male. Head dark in ground-colour, with greyish pruinescence. Dichoptic, upper ommatidia not enlarged. Frons parallel-sided, subequal to width of ocellar triangle; with short setulae along inner margin of eye. Face without setae; parallel-sided, with oral margin dark and shiny. Ocellar triangle slightly elevated, with thin greyish pruinescence, with pair of very short ocellar setae, shorter than length of triangle, with several shorter posterior setulae. Occiput bearing several irregular rows of strong setae, slightly longer than ocellar setae, longer and finer ventrally; postocular setae not differentiated; postocellar region without setae. Antenna dark; scape 1.5× longer than pedicel, with short, black setae; pedicel with ring of apical setae; postpedicel long, gradually tapered, 3× longer than basal width; stylus slightly longer than basal width of postpedicel. Palpus pale, orange brown, with dark setulae. Proboscis reddish brown, slightly longer than head height; labellum with short, dark setae.

Thorax dark brown in ground-colour, densely grey pruinescent. Scutum with 2 pairs of broad, brownish vittae, medial pair ending at prescutellar depression ( Fig. 42 ). Proepisternum with several short, black setae, similar to occipital setae; upper proepisternum in front of spiracle without setae. Prosternum bare. Antepronotum with row of short, black setae, longer laterally. Postpronotum with 1 short seta and several short, dark setae. Scutum with very short uniserial acr on anterior half; dc slightly longer, extending to scutellum; 1 strong posterior npl, with several shorter anterior setae; several presut spal setulae; 0 psut spal; 2 pal setulae. Scutellum with 2–3 pairs of very short sctl setulae, widely separated medially; disc bare. Laterotergite with row of several strong, black setae. Anterior and posterior spiracles pale.

Legs slender, short, femora orange to brown, darker apically, especially on hind femur; tibiae darker, tarsi brown; coxae orange in ground colour, clothed in dense greyish pruinescence, concolourous with pleura ( Fig. 41 ). Coxae with stiff, black setae. Hind trochanter with short setulae. Fore femur clothed in short, black setae. Fore tibia without distinct erect setae, except several preapical setae. Fore tarsomere 1 slender, not swollen; all tarsomeres with biserial row of spine-like ventral setae; tarsomeres 1–4 with apicolateral pair of spine-like setae, longer than width of segment. Mid femur clothed in short, black setae. Mid tibia often with 3–4 anterodorsal and posterodorsal setae; several preapical setae. Mid tarsus similar to fore tarsus. Hind femur with setal tufted anteroventral process arising from inflated, oval ventral lobe; apex with preapical row of 5–6 strong, black posterior setae, longer than width of femur; preapical anterior seta sometimes weakly developed ( Figs 43, 44 ). Hind tibia with proximal half shallowly twisted; anteroventral digitiform process on basal quarter, slightly proximal to process of femur (when legs folded), with black setae on inner margin, shorter than length of process; posteroventrally with broad, triangular process opposite inflated process of femur, with long, black lateral and apical setae, longer than process, with anterior base with dense pruinescence; with seta in posteroapical comb; 3–4 strong, black anterodorsal and posterodorsal setae, shorter than width of tibia ( Figs 43, 44 ). Hind tarsus broader than fore tarsus, otherwise similar in chaetotaxy.

Wing infuscate with dark veins; veins complete, except Sc and CuA+CuP. Basal costal seta absent. R 5 and M 1 parallel near wing margin; R 5 ending at wing tip; radial fork broad. Halter pale, yellowish brown.

Abdomen dark, with dense greyish pruinescence, similar to scutum with very short setae sparse on distal tergites; anterior and posterior margins of tergites distinctly glossy (often anterior margin retracted within preceding segment). Pregenital segments unmodified, except sclerites of segment 8 fused, forming ring. Terminalia ( Fig. 52 ): dark brown with hypandrium and phallus shiny orange brown. Cercus shorter than epandrium, subrectangular; base of cercus fused with epandrium; dorsal margin slightly attenuated distal to mid-length; apex truncate; setae shorter than half width of cercus. Subepandrial process extending to either side of phallus. Epandrial lamella linear, longer than height; posterior margin truncate with short, up-turned dorsal margin; setae similar in length to cercal setae. Hypandrium long, with rounded apical margin; without setae. Phallus with basal half expanded beyond basal curve, not projecting beyond base of apical section; apical half sharply bent at nearly 90°, slightly sinuous; apex not emerging beyond cercus; ejaculatory apodeme less than half-length of epandrium, T-shaped, with lateral apodemes on lower third.

Female. Similar to male, except as follows: frons slightly broader; hindleg without modified setae and processes. Abdominal pleural membrane pale, without expanded region; tergites 7 and 8 pruinescent.

Geographical distribution and seasonal occurrence ( Fig. 54 ). Empis (En.) aerobatica is known from eastern Oregon, Washington and Idaho. Adults have been collected from May to July.

Nuptial gift presentation. Aldrich & Turley (1899) reported that males of this species present to females relatively large balloons containing a small prey item, which may be fed on by the female ( Kessel 1955). The material examined above includes balloons with prey items attached ranging from flies (ceratopogonids, cecidomyiids, chloropids) to Psyllidae and Chalcidoidea. The balloons are fragile in nature and tend to collapse a few hours after collection ( Aldrich & Turley 1899; Kessel & Kessel 1951). The balloons are tubular, with a circular opening at one end and appear to be formed by small bubbles ( Figs 7, 8 ). The prey is found attached to the outer margin of the balloon.

Remarks. One male from the type locality differs in the shape of the phallus from the common form ( Fig. 52 ) of E. (En.) aerobatica accepted here. In this specimen the phallus gradually tapers before the sharp bend and the apical section is strongly sinuous. Since the hindleg appears identical with E. aerobatica , this specimen is considered as conspecific.

Figures

FIGURE 54. Known geographical distribution of E. (Enoplempis) aerobatica Melander.

FIGURES 6–14. Balloons of E. (Enoplempis) species. 6, E. (En.) bigoti Melander (New York Creek, California), mating pair collected with balloon, prey: Psocoptera; 7, E. (En.) aerobatica Melander (3 mi. S Helmer, Idaho), prey: Chloropidae; 8, same, prey: Psyllidae; 9, E. (En.) bigoti Melander (New York Creek, California), prey: Psocoptera; 10, same, paratype of E. bullifera Kessel & Kessel (Novato, California), prey: Chironomidae; 11, same, opposite end of balloon; 12, E. (En.) geneatis (Melander) (Briones Reg. Pk, California), prey: Sciaridae; 13, same (Mill Valley, California), prey: Chalcidoidea; 14, E. (En.) vockerothi Cumming, empty prey-less balloon (Hocking Co., Ohio). Balloons all at same scale, except E. (En.) vockerothi.

FIGURES 41–45. Male habitus, thorax, hindleg and female habitus of E. (Enoplempis) aerobatica Melander. 41, male habitus, lateral view; 42, thorax, dorsal view; 43, hind femur tibia joint, anterior view; 44, hind femur tibia joint, posterior view; 45, female habitus, lateral view.

FIGURES 52–53. Male terminalia of the E. (Enoplempis) bigoti species group, lateral view. 52, E. (En.) aerobatica Melander; 53, E. (En.) bigoti Melander.