Dasyhelea megatheca, Grogan, Willliam L., Díaz, Florentina, Spinelli, Gustavo R. & Ronderos, Maria M., 2016

Grogan, Willliam L., Díaz, Florentina, Spinelli, Gustavo R. & Ronderos, Maria M., 2016, The biting and predaceous midges of Guadeloupe (Diptera: Ceratopogonidae). II. Species of the subfamily Dasyheleinae, Zootaxa 4184 (2), pp. 201-254 : 238-241

Dasyhelea megatheca new species

( Figs. 21–22 )

Diagnosis. The only Neotropical species of the mutabilis group with males distinguished by the posteromedial surface of sternite 9 with medial wrinkles, a greatly curved gonostylus with pointed apex, symmetrical fused paramere and gonocoxal apodemes, and aedeagus with slender, heavily sclerotized, posterolateral arms with pointed tips and posteromedian projection with bifurcate distal portion. Females with a very large (length 118µm) elongate ovoid spermatheca with a very slender neck.

Male. Head ( Fig. 21 A). Dark brown. Eyes contiguous for a distance equal to the width of 2 ommatidia. Frontal sclerite elliptical, moderately short with a slender posterior extension extending to base of clypeus. Antennal flagellum with flagellomeres 2–9 rhomboid, 10–13 elongate, 13 broader than 10–12; flagellomeres 2–10 with single whorl of long sensilla chaetica comprising the dense plume that extends to near apex of flagellomere 12; antennal ratio 0.94–1.07 (0.98, n=10). Clypeus with 6 pairs of setae. Palpus ( Fig. 21 B) light brown; segment 3 slender, as long as 4+5 combined with scattered capitate sensilla; palpal ratio 3.14–4.83 (3.89, n=10). Thorax. Dark brown. Scutellum with 6 large, 3 smaller setae. Wing ( Fig. 21 C) moderately slender; membrane hyaline with moderately dense macrotrichia; veins brown; 2nd radial cell moderately developed, slender with gap between apices of costa, radius; fork of CuA1 at level of base of 2nd radial cell; anal lobe well developed; wing length 0.76–0.86 (0.82, n=10) mm, width 0.28–0.32 (0.29, n=10) mm; costal ratio 0.46–0.51 (0.48, n=10). Abdomen. Dark brown. Genitalia ( Figs. 21 D, 22A). Tergite 9 broad on proximal half, distal half tapering progressively distally to rounded apex that extends to apices of gonocoxites; apicolateral process very short, conical with stout apical seta; cercus very small with 3–4 setae. Sternite 9 ( Figs. 21 D, 22B) moderately long, 0.46 length of greatest width; posteromedian portion broad proximally, distal half tapering slightly with broad, slightly notched apex, medial surface with 4 elongate wrinkles. Gonocoxite stout, twice as long as broad, broadest distally, apicomesal surface with group of dense, moderately long setae; gonostylus 0.86 length of gonocoxite, proximal 1/3 broad at base, gradually tapered, distal 2/3 slender, greatly curved, apex slightly broader with pointed tip. Paramere and gonocoxal apodemes ( Fig. 22 C) forming a symmetrical structure; gonocoxal apodemes sinuate, stout proximally, tapering distally; paramere very slender, extending to apex of aedeagus. Aedeagus ( Fig. 22 D) 0.60 length of greatest width; basal arch low, lightly sclerotized, anterior margin slightly convex, distal margin with rounded excavation; posterolateral arms heavily sclerotized, convergent, broad proximally, tapering abruptly distally to slender apex with sharply pointed tips that almost touch; posteromedian projection with semi-triangular proximal portion, overlapping to basal arch, distal portion deeply bifurcate, with slender distal processes that extend just beyond apex of sternite 9.

Female. Head ( Fig. 21 E). Dark brown. Eyes contiguous for a distance equal to the width of 2.5 ommatidia. Frontal sclerite ( Fig. 21 F) similar to male. Antennal flagellum with flagellomeres 2–8 vasiform, slightly longer than broad, 11–14 slightly longer than 2–8, 13 longest; antennal ratio 0.85–0.96 (0.90, n=3). Clypeus ( Fig. 21 F) with 11 pairs of setae. Palpus ( Fig. 21 G) brown; segment 3 about as long as 4+5 combined with 2–3 capitate sensilla on basomesal surface; palpal ratio 3.12–3.71 (3.36, n=3). Thorax. Scutum dark brown; scutellum paler with 6 large, 4 smaller setae. Femora, tibiae brown, tarsi slightly paler; hind tibial comb with 6 spines, 2nd longest; prothoracic tarsal ratio 1.62–1.94 (1.80, n=3), mesothoracic tarsal ratio 1.92–2.11 (2.01, n=3), metathoracic tarsal ratio 1.95–2.10 (2.03, n=3). Wing ( Fig. 21 H) moderately broad; membrane hyaline with dense macrotrichia; 2nd radial cell reduced to a suture; apices of costa, radius at slight acute angle; fork of CuA1 at level of base of 2nd radial cell; wing length 0.72–0.74 (0.73, n=3) mm, width 0.32–0.34 (0.33, n=3) mm; costal ratio 0.50–0.53 (0.51, n=3) mm. Halter pale. Abdomen (Fig. ( Fig. 21 I). Dark brown. Subgenital plate ( Fig. 21 J) sub-circular, posteromedian margin rounded; posterolateral arms slender, nearly straight. Spermatheca ( Fig. 21 I) large, elongate ovoid, very heavily sclerotized with moderately thick walls, length/width 118 x 64 µm, neck moderately long, very slender, slightly curved, length 10 µm.

Distribution. Guadeloupe.

Type material. Holotype male, labeled “ Guadeloupe, Basse Terre Pigeon , 9-IX-2011, MC Thomas & RH Turnbow, Blacklight trap ” ; allotype female with same data except “ NE Pigeon (16.14404º N, 61.74977º W), 17-V- 2012, RH Turnbow, BL trap ” (deposited in FSCA) . Paratypes 27 males, 3 females, as follows: same data as holotype 3 males, 1 female ; same data as allotype 12 males ; same data except Pointe a Lezard, 20-V-2012, 3 males ; same data except, La Trace du Petit-Malendure , 21-V-2012, 9 males, 2 females .

Derivation of specific epithet. The specific epithet is a combination of two Greek terms, mega (large) and theca (a case), in reference to the large, elongate spermatheca of females of this new species.

Discussion. Dasyhelea megatheca n. sp. is readily distinguished from all other Neotropical congeners by the characters provided in the diagnosis and the key. Dasyhelea bermudae differs from this new species by the short and stouter gonostyli and by the recurved apices of the posterolateral arms of the aedeagus; D. guadeloupensis differs by the gonocoxal apodemes and paramere forming an asymmetrical structure and by the aedeagus with crescent-shaped basal arch and moderately long, curved, widely separated posterolateral arms with medially directed apices; and D. sp. nr. thomsenae differs by the J-shaped paramere.

Figures

FIGURE 21. Dasyhelea megatheca n. sp. Holotype male, A – D, Allotype female, E – J. A, E. head. B, G. palpus. C, H. Wing. D. genitalia. F. frontal sclerite and clypeus. I. abdomen and spermatheca. J. subgenital plate.

FIGURE 22. Dasyhelea megatheca n. sp. Holotype male. A. genitalia. B. sternite 9. C. gonocoxal apodemes and paramere. D. aedeagus. Scale bar: 0.05 mm.