Dasyhelea bermudae Wirth and Williams
Creators: name: Grogan, William L.
name: Hribar, Lawrence J.
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Ceratopogonidae
Dasyhelea
Dasyhelea bermudae

description: Dasyhelea bermudae Wirth and Williams
(Figs. 9–16)
Dasyhelea bermudae Wirth & Williams, 1957: 11 (Bermuda); Wirth 1965: 126 (in Nearctic catalog north of Mexico); Borkent & Spinelli, 2000: 24 (in New World catalog south of the USA; distribution); Borkent & Spinelli, 2007: 60 (in Neotropical catalog; distribution); Grogan et al. 2016: 34 (Guadeloupe record); Borkent & Dominiak 2020: 43 (in World Catalog).
Diagnosis. A small species of the D. atlantis-bermudae complex distinguished from other species in this complex by the following combination of characters. Males small, wing length 0.67–0.72 (0.69, n=5) mm; disto-median portion of aedeagus tubular, moderately short, apex extending to or near apices of gonocoxites, tip concave with recurved apicolateral extensions; tergite 9 short, apex broadly rounded with very short apicolateral processes which bear a single large subapical seta; gonocoxal apodemes and paramere slightly asymmetrical, barely fused or separated with a lightly sclerotized triangular posterior process. Females small, wing length 0.63–0.69 (0.66, n=3) mm; subgenital plate ovoid with ellipsoid lumen; spermatheca large, globular, dark brown, heavily sclerotized, with thick walls, and a short nipple-like neck.
Redescription of Male. Head (Figs. 9–10): Dark brown. Eyes contiguous for the length of 3–4 ommatidia, with moderately dense, fine pubescence. Frontal sclerite elliptical with very slender ventral projection. Antennal flagellum medium brown, all flagellomeres with well-developed surface reticulations; flagellomeres separate, 5–10 partially or completely fused in some specimens; flagellomere 2 globular, 3–5 rhomboid, 7–9 broadly vasiform, 10–12 elongate vasiform, 13 with slightly tapered apex, flagellomere 11 or 13 longest; flagellomeres 1–12 with subbasal whorl of sensilla chaetica, those on 2–12 elongated and composed the moderately dense plume that extends beyond flagellomere 12; antennal ratio 0.81–0.93 (x̄=0.87, n=5); total flagellum length 0.44–0.48 (0.46 mm, n=5). Palpus 5-segmented, light brown; segment 3 slender with 0–1 long, subbasal capitate sensilla; palpal ratio 3.17–4.00 (3.63, n=5). Thorax (Figs. 9–10): Scutum dark brown; scutellum yellow except lateral margins brownish with 6–7 large setae, 0–2 smaller anterocentral setae; lateral, ventral sclerites medium dark brown. Femora, tibiae medium brown, femora slightly darker than tibiae; tarsi with tarsomeres 1–4 light brown, tarsomeres 5 darker; claws small, equal-sized, straight with basal inner seta, apices bent, tips bifid; hind tibial comb with 6 spines, 4–5 longest; hind tarsal ratio 1.94–2.12 (2.04, n=5). Wing (Fig. 10) moderately broad, membrane slightly infuscated, covered with dense macrotrichia, 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, 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; costa short, costal ratio 0.42–0.47 (0.45, n=5); wing length 0.67–0.72 (0.69, n=5) mm, width 0.26–0.27 (0.27, n=3) mm. Halter stem brown; knob pale (the basal half of the knob is pale in one specimen), distal half whitish (appearing black under compound microscope). Abdomen. Tergites medium dark brown, sternite lighter brown. Genitalia (Figs. 11–12). Tergite 9 broadest at base, anterior margin nearly straight, surface with scattered 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; cercus apparently reduced to very low mound on inner base of apicolateral process with 2–5 short setae; sternite 9 narrower basally than tergite 9, tapering gradually distally on proximal 2/3, tapering more abruptly on distal 1/3, apex curved, extending just below or to base of aedeagus. Gonocoxite short, stout, 1.3–1.4 X longer than broad, ventrolateral surface with scattered sparse long setae, mesoventral setae with more numerous shorter setae; gonostylus 0.90–0.95 length of gonocoxite, broadest at base, proximal 2/3 covered with short fine setae, tapering slightly distally at proximal 1/3, slightly curved, apex moderately broad, rounded with small to well-developed apicoventral “beak.” Gonocoxal apodemes and paramere slightly asymmetrical, separated or barely fused; basal apodemes heavily sclerotized, proximal 1/5 more or less quadrate in shape, set at 60̊ angle with junction of distal 4/5 stem, distal stem recurved at midlength nearly 90̊, apices slightly tapered, tips slightly offset, with broad lightly sclerotized more or less triangular posterior sclerite that is difficult to see in some specimens. Aedeagus complex, composed of two sections; proximal sclerite heavily sclerotized, in shape of transverse bar with short basal arms, lateral arms mostly moderately sclerotized, tilted at 30̊ mesally, tapering very slightly distally with slender, heavily sclerotized apex that is recurved laterally 90̊; distal portion lightly sclerotized, tubular, basal half triangular, apical half straight, parallel-sided, apex more heavily sclerotized, deeply concave medially with small flared, recurved apicolateral processes.
Redescription of Female. Similar to male with the following notable sexual differences. Head (Fig.13): Antennal flagellomeres separate, with poorly developed surface reticulations; flagellomeres 9–13 slightly longer than 2–8, 13 longest; flagellomeres with basal whorl of moderately long sensilla chaetica; antennal ratio 0.85–0.88 (0.86, n=3); total flagellum length 0.365 –0.383 (0.379, n=3) mm. Palpal segment 3 with 2–3 capitate sensillae; palpal ratio 3.00–3.60 (3.29, n=3). Thorax (Fig. 14): Hind tarsal ratio 1.97–2.16 (2.08, n=3); claws more gradually curved, apices very slender, tips entire. Wing (Fig. 15) broader than male; anal lobe slightly better developed; wing length 0.63–0.69 (0.66, n=3) mm, width 0.28–0.32 (x̄=0.30, n=3) mm; costal ratio 0.45–0.46 (0.46, n=3). Abdomen (Fig.16): Genital sclerotization with distal portion ovoid with broad ovoidal lumen; proximal portion broad basally, basal arms tapering gradually distally, bent at midlength. Spermatheca globular to slightly ovoid, very heavily sclerotized with thick walls, 0.97–1.24 X broader than long (two are slightly deformed, one is tilted); length 0.064 – 0.071 (0.067, n=3) mm, width 0.066 –0.082 (0.072, n=3) mm; neck short, stout, straight, nipple-like in shape.
Discussion. Both sexes of D. bermudae are slightly smaller than those of D. atlantis, however, males of both species have slightly longer average wing lengths than their conspecific females, but their wings are narrower than females. Costal ratios of female D. bermudae are slightly lower (0.45–0.46) than females of D. atlantis (0.47–0.51), but no apparent differences in female antennal and hind tarsal ratios were noted in measured specimens. Females of D. atlantis apparently have a wider range of palpal ratios (3.45–5.00, n=10) than D. bermudae (3.00–3.60, n=3), but this may be partially due to the small sample size of the latter species. However, their female genital sclerotizations and spermathecae are very different, and we consider these two characters are best for identifying females of both species.
Bionomics. Wirth & Williams (1957) described D. bermudae from specimens collected in recovery cages during June and July 1955 from seven localities that were plotted on a map of the Bermuda Islands in Williams (1956). He also provided details on 15 microhabitats of several other species of Ceratopogonidae on Bermuda. Seven of these sites yielded 51 males and 75 females (the type series) of D. bermudae from South Shore Marsh on Pampas Farm (type locality), drainage ditches at Devonshire, Paget, South and Warwick Marshes, and from Seymor, Trott’s, and Warwick Ponds (Williams 1957).
Material Examined. BERMUDA, 21–27 June 1955, R. W. Williams, Pampas Farms recovery cage II, 1 female (allotype, USNM), 1 male (paratype); same data except 28 June 1955, recovery cage Paget Marsh, 2 males (paratypes); same data except July 1955, recovery cage Warrick Marsh, 1 female, 1 male (paratypes); Camden, 20- VII-1968, Dr. I. Hughes, 20-VII-(19)68, 1 female, (labeled by W. Wirth as D. atlantis, an obvious lapsis) (USNM). Guadeloupe, Basse Terre, NE Pigeon (16.1440N, 61.74977W) 8-V-2012, R. H. Turnbow, BL trap, 1 male (FSCA).
description: Published as part of Grogan, William L. & Hribar, Lawrence J., 2025, New Species of Biting Midges in the Dasyhelea atlantis-bermudae Complex (Diptera: Ceratopogonidae), pp. 519-536 in Zootaxa 5613 (3) on pages 523-526, DOI: 10.11646/zootaxa.5613.3.5, http://zenodo.org/record/15216840