Dasyhelea atlantis Wirth and Williams

Dasyhelea atlantis Wirth and Williams View in CoL

( Figs. 1–8 View FIGURES 1–8 )

Dasyhelea atlantis Wirth & Williams, 1957: 11 View in CoL ( Bermuda); Waugh & Wirth 1976: 245 (records from Florida and New York (Long Island); redescription; figs. female, male, pupa); Davies & Giglioli, 1979: 592 (records from Grand Cayman); Wilkening et al. 1985: 519 (record from Indian River Co., Florida); Borkent, 1991: 108 (records from the Galápagos Islands and Maine, USA; description, figs.); Borkent & Spinelli, 2000: 24 (in Catalog of New World species south of the USA; distribution); Borkent & Spinelli, 2007: 59 (in Neotropical Catalog; distribution); Borkent & Grogan, 2009: 11 (in Catalog of New World Biting Midges North of Mexico; distribution); Grogan et a l. 2010: 21 (records from Florida Keys, Monroe Co.); Borkent & Dominiak 2020: 42 (in World Catalog).

Diagnosis. A medium to large species in the D. atlantis-bermudae complex distinguished from all other species in this complex by the following combination of characters. Male aedeagus elongate, tubular, the apex extending to or near apices of gonocoxites, basal portion with moderately long recurved apicolateral extensions; aedeagus length/width ratio 0.93–1.75 (1.27, n=18); wing length 0.70–0.91 (0.80, n=20) mm, width 0.25–0.29 (0.28, n=20) mm; costa moderately long, costal ratio 0.44–0.48 (0.46, n=20); gonocoxal apodemes and paramere asymmetrical, divided; tergite 9 elongate, extending beyond gonocoxites with rounded apex and moderately long, stout apicolateral processes; sternite 9 moderately long with convex apical margin. Female wing length 0.59–0.91 (0.68, n=21) mm, width 0.28–0.44 (0.32, n=19) mm; antenna with moderately elongate flagellomeres 9–13; sub-genital plate subcircular with basolateral ear-like extensions, lumen cordiform usually with basal pointed extension, posterior excavation very deep; spermatheca large, length 0.04–0.09 (0.05, n=18) mm, subspherical with narrow slender neck.

Redescription of Male. Head ( Fig. 1 View FIGURES 1–8 ): Dark brown. Eyes contiguous for a distance equal to the length of 2–4 ommatidia, with moderately dense, fine pubescence. Frontal sclerite elliptical with slender ventral projection. Antennal flagellum medium brown, all flagellomeres with surface reticulations; flagellomeres 3–11 partially or completely fused in some specimens, 10–13 elongate; antennal ratio 0.96 (0.90–1.03, n=17); total flagellum length 0.53 (0.49–0.56, n=17) mm. Palpus light brown; segment 3 moderately long, slender with capitate sensillae; palpal ratio 3.60–6.00 (5.91, n=19). Thorax ( Fig. 2 View FIGURES 1–8 ): Scutum brown; scutellum yellow with 6–7 large, 0–2 smaller anterocentral setae. Femora, tibiae medium brown, femora slightly darker than tibiae; hind tibial comb with 6 spines, 4 th or 5 th longest; tarsomeres 1–4 light brown, tarsomeres 5 darker; claws small, equal-sized, straight with basal inner seta, apices bent, tips bifid; hind tarsal ratio 2.21 (2.05–2.31, n=20). Wing ( Fig. 3 View FIGURES 1–8 ) moderately slender, membrane slightly infuscated, covered with dense microtrichia, macrotrichia moderately dense on all veins except basal portion of medius and in all cells except proximal portion of cua 1 and anal cell; radius and proximal portion of medius brown; one narrow to moderately broad radial cell in some specimens, reduced to a suture in others; basal 1/3 of proximal portion of medius poorly developed, reduced to 9–10 small, circular beadlike sclerites; extreme basal section of vein M 1 poorly developed, weakly joined to basal portion of medius, not connected to M 2; anal lobe moderately developed; wing length 0.70–0.91 (0.80, n=20) mm, width 0.25–0.29 (0.28, n=20) mm; costa moderately short, costal ratio 0.44–0.48 (0.46, n=20). Halter stem brown; knob white. Abdomen. Genitalia ( Figs. 4–5 View FIGURES 1–8 ). Tergites ( Fig. 2 View FIGURES 1–8 ) dark brown, sternites lighter brown. Tergite 9 broadest at base, anterior margin slightly extended on mid-portion, apex with numerous very long setae, tapering distally at level of basal point of paramere apodemes, apex broadly rounded, extending considerably beyond gonocoxites; apicolateral process stout with single apical seta Aedeagus elongate, tubular, the apex extending to or near apices of gonocoxites, basal portion with moderately long recurved apicolateral extensions. Aedeagus length/width ratio 0.93–1.75 (1.27, n=18).

Redescription of Female. Similar to male but more massive with the following notable sexual differences. Head. ( Fig. 6 View FIGURES 1–8 ). Antennal flagellomeres separate with poorly developed surface reticulations; 9–13 considerably longer than 2–8, 13 longest; flagellomeres with basal whorl of long sensillae chaeticae; antennal ratio 0.82–0.96 (0.89, n=24) mm; total flagellum length 0.33–0.50 (0.38, n=24) mm. Palpal segment 3 with 1–3 capitate sensillae; palpal ratio 3.45–5.00 (4.15, n=18). Thorax. Hind tarsal ratio 2.00–2.26 (2.19, n=22); claws gradually curved on distal 1/4, apices slightly recurved, tips entire. Wing ( Fig. 7 View FIGURES 1–8 ) broader than males, anal lobe more developed; length 0.59–0.91 (0.68 n =21) mm, width 0.28–0.44 (0.32, n=19) mm; costa moderately long, costal ratio 0.47–0.52 (0.50, n=21). Abdomen ( Fig. 8 View FIGURES 1–8 ). Genital sclerotization very distinctive, distal portion ovoid with a broad ovoidal lumen; basal portion broad basally, lateral arms elongate with blunt apices and a deep central excavation. Spermatheca globular, tapered distally with a short to moderately long slender neck; length 0.04–0.09 (0.05, n=18) mm, width 0.03–0.05 (0.04, n=12) mm.

Discussion. This species was subsequently recorded in the USA from Florida and New York by Waugh and Wirth (1976), from the Cayman Islands by Davies and Giglioli (1979), and the Galápagos Islands and Maine ( USA) by Borkent (1991). We provide the first records from Mexico and an additional USA record from Maryland. Wirth and Williams (1957) gave female wing lengths of 0.75–0.80 mm from Bermuda, and Borkent (1991) listed female wing lengths of 0.65–0.82 mm from the Galápagos Islands. We recorded female wing lengths of 0.59–0.79 (0.72, n=20) mm.

Bionomics. Davies and Giglioli (1979) noted on Grand Cayman that D. atlantis was “exceedingly common, being found everywhere in light traps. Adults were found resting in tall grass and herbs in flooded pastures and on pneumatophores in mangrove areas. During 3 days when flooding was actually taking place the emergence rate went up to 373.0 per day. …Thus D. atlantis is probably the most common ceratopogonid in Grand Cayman, breeding in habitat from fresh to brackish and flooded to almost dry. Flooding seems to stimulate emergence.”

Material Examined. BERMUDA, 17–23 June 1955, R. W. Williams, recovery cage Spittal Pond , 1 female (allotype, Type No. 62198; USNM) , 2 males (paratypes; USNM) ; same data except 7–12 June 1955, recovery cage Wilkenson Pond , 1 female (paratype; FSCA) , 1 male (paratype; USNM) ; same data except 4 July 1955, recovery cage Warrick Pond , 1 female (paratype; USNM) ; Camden , 23-VII-(19)68, Dr. I. Hughes, 1 male ( USNM) . CAYMAN ISLANDS, Grand Cayman , Dec. 1973, J. E. Davies, 3 males, 3 females ( USNM) . USA: FLORIDA, Indian River Co., “Vero Beach”, Ent. Res. Cntr., April 1960, light trap, 1 female. Miami-Dade Co. , Pinecrest Chapman Field , 5–11-1-2016, H. Escobar, Suction Trap, 1 male, 1 female ( FSCA) . Monroe Co., Lower Sugarloaf Key , 8 August 2012, Run 3, 20:14–20:28, L. Hribar & C. Pruszynski, Truck Trap, 1 female ; same data except 4 Sept. 2012, C. Pruszynski, Truck trap, 1 male; No Name Key, 2 Feb. 2009, D. DeMay, 1 female, 1 male; Vaca Key, 10 Sept. 2010, L. Hribar, BG Sentinel trap, 1 female; Upper Key Largo , 9/ 14 June 2014, K. E. Schnepp, Funnel Trap, 1 female; (all FSCA) . MARYLAND, St. Marys Co., St. George , 14-VI-1970, 1 female ( USNM) . NEW YORK, Suffolk Co., Long Island, Orient , 25-V-1963, W. Wirth, salt marsh, 1 male ( FSCA) . MEXICO, Cancun , Quintana Roo, 1-III-(19)75, D. Pletsch, LT, 1 male ( USNM) .