Curtonotum bivittatum Klymko & Marshall, 2011

Klymko, John & Marshall, Stephen A., 2011, Systematics of New World Curtonotum Macquart (Diptera: Curtonotidae) 3079, Zootaxa 3079 (1), pp. 1-110 : 39-43

Curtonotum bivittatum Klymko & Marshall , sp. n.

Figures 43–50 , 206 , and 207

Etymology. From Latin, bis, meaning two, and vitta, meaning stripe, referring to the two bold vittae of the frons that continue onto the scutum.

Diagnosis. Curtonotum bivittatum can be distinguished from most C. bathmedum specimens by the more extensive infuscation around M 1 proximal to crossvein dm-cu: in C. bivittatum infuscation extends 0.24–0.45 times the distance from dm-cu to r-m, in C. bathmedum infuscation extends between 0.10–0.26 times the distance from dm-cu to r-m, thus the infuscation along M 1, dm-cu, and CuA 1 often forms a zig-zag. The two species can be definitively distinguished by the distiphalli—in C. bivittatum the distiphallus is elongate, with a coarse spinose dorsal ridge on distal two-thirds ( Figures 43 and 45 ), in C. bathmedum the distiphallus shorter, with a broad finely spinose apex ( Figures 51 and 53 ), and by the ventral receptacle—in C. bivittatum the ventral receptacle has a bulbous, subspherical head ( Figure 50 ), in C. bathmedum the ventral receptacle has a hemispherical head ( Figure 57 ).

Description. Length: 5.9–8.8 mm.

Head: Frons dark yellow with 2 prominent brown vittae, brown vittae with white sheen (only visible from oblique angle); frons with stronge bulge ventrally and sparsely scattered minute black setulae, lateral margins shiny silver microtomentose, width 1.0–1.1 times height, parallel sided to slightly wider ventrally. Ocellar triangle and narrow strip on either side of frons gold microtomentose, microtomentum of ocellar triangle not extending anterior of anterior ocellus, narrow microtomentose strip extending just ventral of proclinate seta. Proclinate seta at ca. onethird sagittal distance from anterior ocellus to ventral margin of frons, anterior to and in some specimens slightly medial of major reclinate seta; minor reclinate seta ca. midway between proclinate and major reclinate setae. Face silver microtomentose with pale yellow ground colour; vibrissa no larger than adjacent subvibrissals. Parafacial very broad, silver microtomentose with pale yellow ground colour; gena brown-yellow, only lightly microtomentose, bare and shiny medially, eye height 8.3–10.8 times gena height. Clypeus and palpus with pale yellow ground colour, former gold microtomentose, latter with gold microtrichia; prementum lightly gold microtomentose, with yellow ground colour. Antennae with orange-yellow ground colour, scape and pedicel gold microtomentose, setulae on scape black, on pedicel black dorsally and dark orange or black ventrally, first flagellomere with gold microtrichia, ground colour slightly darker on apical quarter to third.

Thorax: Scutum moderately arched, with orange-yellow ground colour, dull gold microtomentose with 2 pairs of prominent brown vitta; medial vitta appearing as continuation of vitta on frons, broadening distally, extending onto scutellum, lateral vitta anteriorly on medial portion of postpronotal lobe and notopleuron, broken at transverse suture, posteriorly more medial, between medial and transverse vitta an additional short vitta on postsutural area. Setulae and setae on gold microtomentose areas with dark haloes around insertion points. Postpronotal lobe with 2 prominent setae, anterior seta ca. two-thirds length of posterior seta; notopleuron without setulae, scutellum with 2 pairs of marginal setae. Laterally with vitta from lateral portion of postpronotal lobe to base of wing, otherwise subshiny, with yellow ground colour and moderate gold microtomentum. Anepisternum with 3 prominent setae and 2 or 3 lesser setae on posterior half; katepisternum with single prominent lateral seta; linear tuft of setulae under fore coxa yellow. Area below and behind posterior spiracle bare (without fringe of setulae); meron bare (2 or 3 minute orange setulae sometimes present).

Legs: Ground colour yellow, except where noted, coxae densely silver microtomentose, legs otherwise lightly so, subshiny. Chaetotaxy black, except for very dense, regularly spaced transverse rows of setulae anteroventrally on apical third of fore tibia and similar setulae on fore tarsomere 1, the former gold-yellow, the latter slightly darker. Fore femur with 3–5 posterodorsal setae, ctenidial setae hardly differentiated from adjacent setulae (as such count not possible); mid femur with 5–6 anterior setae; hind femur with single anterodorsal seta. Mid tibia brown anterodorsally for entire length, with 2 prominent and 1–2 moderate apical ventral setae, 1 moderate seta posterior to the 2 prominent setae, its size variable (though always present), in some specimens nearly as long as prominent setae, in others ca. half as long, an additional moderate seta often present between the 2 prominent setae; hind tibia occasionally brown anterodorsally for entire length, often brown at apex. Row of short cuneiform setae present on anteroventral margin of mid and hind tarsomere 5.

Wing: Alula very narrow. Non-infuscated areas with yellow tinge. Costal cell, r 1, and anterior half of r 2+3 dark brown infuscated, r 2+3 broadly dark brown infuscated apically; r 4+5 medium to dark brown infuscated apically, and posteriorly along margin from apex to between crossveins dm-cu and r-m, the proximal limit of this infuscation at between 0.24–0.45 times the distance from dm-cu to r-m; m 1 broadly medium brown infuscated along margin, infuscation paler distally, dm broadly medium brown infuscated along distal margin, anterior margin opposite infuscation in r 4+5, and posterior margin to level of r-m; cua 1 broadly medium brown infuscated along anterior margin to level of r-m.

Abdomen: Gold microtomentose, ground colour yellow, markings produced by changes in ground colour and microtomentum. Posterior ca. quarter of tergites 2–4 yellow-brown, darker toward posterior margin (this present on tergite 5 in some specimens), tergites 3–5 with dark brown medial vitta (this much broader posteriorly on each tergite).

Male terminalia: Sternite 5 truncate posteriorly, with small invaginate area of weak sclerotization, this invagination free of setulae. Tergite 6 broad, setulose in some specimens; tergite 7 weakly sclerotized, short, dorsal length slightly more than one-tenth dorsal epandrial length; sternites 6 and 7 weakly sclerotized, folded over, but not interrupted at protandrial fold; sternite 6 broad, more heavily sclerotized ventrally on left; sternite 7 relatively long, length of right portion ca. 0.6 times length of right portion of sternite 6. Epandrium relatively large, setulose (in no one area these particularly long), fused below cerci, area of fusion with distinct bulge in lateral profile; surstylus narrow, posterior margin flat, articulating laterally with and medially fused to epandrium, hind margin straight, mediodistal corner acute, minutely setulose above and below. Cercus stout, ventral margin flat, broadly rounded posteriorly, longest cercal setulae longer than longest epandrial setulae. Hypandrium with low, broad-based, acute posterodorsal lobe, posterior bridge produced ventrally and posteriorly, hypandrial arm straight in lateral profile, broadly fused distally to opposite hypandrial arm, with 4–5 posteroventrally oriented small setulae inserted on small ventral projection just posterior of epandrial posterior margin; postgonite straight, sparsely and minutely setulose distally, occluded by or slightly exceeding surstylus ventrally. Phallapodeme with large “fan”, margin opposite fan concave; basiphallus moderately to broadly expanded and well sclerotized basally, moderately to strongly tapered distally; distiphallus composed of 2 elongate heavily sclerotized processes lateral to one another, these connected by membrane, separated into 2 lobes on distal ca. quarter, basal third of left lobe broad and flaring to left, apical two-thirds narrow and well sclerotized except apical membranous expansion, with stout marginal spines (at apex spines limited to ventral face of membranous expansion), right lobe broader, smooth, distal quarter bulbous and somewhat membranous, otherwise well sclerotized, with fine small spinules at apex. Ejaculatory apodeme within or at proximal edge of basiphallus, elongate, expanded and with small pores basally.

Female terminalia: Sternite 5 length 2.2–2.5 times width, sternite 6 length 0.8–1.0 times width. Ovipositor stout. Tergite 7 well sclerotized medially; tergite 8 well sclerotized proximally; sternite 8 weakly so. Sternite 8 varying somewhat in relative length, contracted distally, distal ca. one-sixth a very heavily sclerotized nub with lateral dimples, its dorsoventral height subequal to its width, extent of microtrichosity and setulation on nub variable. Sternite 10 broad, roughly pentagonal. Cerci relatively squat. Spermatheca elongate, apically rounded and often broad based, surface variable, some with low dense protuberances, others with network of fine raised ridges, some intermediate. Ventral receptacle with well-sclerotized squat neck, its margins somewhat concave, apex bulbous, subspherical, lightly sclerotized, duct finely wrinkled longitudinally.

Comments. The two female specimens from Costa Rica have more heavily marked wings ( Figure 207 ), shorter and less shiny genae (eye height 13.8–14.0 times gena height), fewer and stronger subvibrissals (subvibrissal seta number and relative strength variable in other C. bivittatum , but in no other specimens are they as few or strong), setulae posterior to posterior spiracle, and no moderate seta posterior to the most posterior major apical ventral seta on the mid tibia. Their ventral receptacles are similar to other C. bivittatum . Their spermathecae are coarsely papillose, and in one specimen the apex is acute. These two specimens may represent an additional undescribed species, but until males are examined this is difficult to state with certainty—the differences listed may represent regional variation. Therefore, these two specimens are here treated as C. bivittatum , but are not treated as paratypes .

Type material. Holotype: ♂, ECUADOR. Napo: Jatun Sacha Res. , 6 km E Misahualli, 450 m, SOL trail, 1˚4’S, 77˚37’W, 30.iv–8.v.2002, S.A. Marshall ( QCAZ) . Paratypes: COLOMBIA. Cauca: 3♂, ♀, Gorgona Island, 2.59˚N, 78.20˚W, vii.1924, L.E. Cheeseman, St. George Expedition , British Museum 1925–573 ( BMNH) . ECUA- DOR. Napo: 3♀, Jatun Sacha Res. , 6 km E Misahualli, 450 m, 1˚4’S, 77˚37’W, 30.iv–8.v.2002, S.A. Marshall , ♀, 6.v.2002, M. Buck, same data plus SOL trail , 2♀, 30.iv–8.v.2002, S.A. Marshall, same data minus SOL trail plus dung baits on logs , ♂, 3♀, 5.v.2002, O. Lonsdale (all DEBU) ; ♂, ♀, Misahualli near Tena , 6–19.x.2001 ( UTAH) . Orellana: ♂, Tiputini Biodiversity Station, near Yasuni National Park, 0˚37’55”S, 76˚8’39”W, 220 m – 250 m, Lot 2016, Transect 2, Station 7, fogging in terra firme forest, T.L. Erwin et al. 9.ii.1999 ( USNM) ; ♀, Puerto Orellana, Rio Tiputini , 0˚38.2’S, 76˚8.9’W, 12–26.viii.1999, W.N. Mathis, A. Baptista, M. Kotrba ( USNM) ; 2♀, Coca, Napo River , 250 m, v.1965, L. Pena ( CNCI) . Pastaza: ♀, Tzapino, 32 km NE of Tewaeno, Malaise trap, 20–23.v.1976, J. Cohen, Ecuador-Peace Corps-Smithsonian Institution Aquatic Insect Survey ( USNM) .

Other material examined. COSTA RICA. Cartago: ♀, La Suiza, 14.iv.1924 , ♀, 2.ix.1924, all P. Schild (all USNM) .

Figures

FIGURES 43–45. Curtonotum bivittatum Klymko & Marshall, sp. n. 43. Male terminalia, left lateral. 44. Male terminalia, posterior. 45. Distiphallus, dorsal.

FIGURES 46–50. Curtonotum bivittatum Klymko & Marshall, sp. n. 46. Ovipositor, left lateral. 47. Female sternite 10, ventral. 48. Female sternite 8, ventral. 49. Spermatheca. 50. Ventral receptacle.

FIGURES 203–209. Wing. 203. Curtonotum helvum (Loew). 204. Curtonotum floridense Klymko & Marshall, sp. n. 205. Curtonotum nigrum Klymko & Marshall, sp. n. 206. Curtonotum bivittatum Klymko & Marshall, sp. n. 207. Curtonotum bivittatum Klymko & Marshall, sp. n. (Costa Rica). 208. Curtonotum bathmedum Hendel. 209. Curtonotum apicale Hendel.

FIGURES 51–57. Curtonotum bathmedum Hendel. 51. Male terminalia, left lateral. 52. Male terminalia, posterior. 53. Distiphallus, dorsal. 54. Female sternite 8, ventral. 55. Female sternite 10, ventral. 56. Spermatheca. 57. Ventral receptacle.