Curtonotum nigrum Klymko & Marshall, 2011

Klymko, John & Marshall, Stephen A., 2011, Systematics of New World Curtonotum Macquart (Diptera: Curtonotidae) 3079, Zootaxa 3079 (1), pp. 1-110 : 37-39

Curtonotum nigrum Klymko & Marshall , sp. n.

Figures 40–42 , and 205

Etymology. From Latin, niger, meaning black, referring to the very dark overall colouration of this species.

Diagnosis. The combination of an entirely grey-brown infuscate wing and an abdomen devoid of maculae and vittae distinguish C. nigrum from all New World congeners. It is also the only species that has an essentially bivalved right distiphallic lobe (created by a deep invagination on the left margin of the lobe).

Description. Based on holotype.

Length: 5.8 mm.

Head: Frons dark brown with pale medial vitta and pink-purple iridescence (especially in lateroventral corner, iridescence visible only from oblique angle), moderate bulge ventrally and scattered dark setulae, width 1.3 times height, parallel sided, lateral margin narrowly silver microtomentose. Ocellar triangle and narrow lateral strip brown-grey microtomentose, microtomentum of ocellar triangle not extending anterior of anterior ocellus, lateral microtomentose strip extending nearly to midpoint between proclinate seta and ventral margin of frons. Proclinate seta at ca. midpoint of sagittal distance between anterior ocellus and ventral margin of frons, directly anterior to major reclinate seta; minor reclinate seta anterior to and medial of major reclinate seta. Face silver microtomentose with dark brown ground colour; vibrissa ca. twice as long as adjacent subvibrissals. Parafacial and gena narrow, former densely silver microtomentose, latter moderately so, ground colours yellow-brown and dark brown, respectively, eye height 14.7 times gena height. Clypeus, palpus, and prementum with dark brown ground colour, former two silver microtomentose and microtrichose, respectively, latter bare and shiny. Scape and pedicel with orangebrown ground colour and silver microtomentum, first flagellomere densely silver microtrichose, with orangebrown ground colour on proximal ca. quarter, otherwise dark brown.

Thorax: Silver microtomentose with dark brown ground colour throughout (except scutellum, where microtomentum is brown), ground colour paler around postpronotal lobe, anterior spiracle, base of wings and margin of scutellum. Scutum moderately arched, each scutal, postpronotal, and anepisternal seta and setula with dark spot around socket. Scutum with 2 faint pairs of narrow dark vittae, medial pair running entire scutal length, lateral pair evident only posterior of transverse suture. Postpronotal lobe with 3 setae, center seta ca. 0.6 times length of posterior seta, anterior seta smaller still; notopleuron without setulae; scutellum with 2 pairs of marginal setae. Left anepisternum with 3 subequal large setae on posterior half, right anepisternum with 2 large and 2 moderate setae on posterior half (this asymmetrical condition is almost certainly an individual aberration and the condition of the right anepisternum is most likely typical); katepisternum with single prominent lateral seta (2 setulae in the native position of the second lateral seta suggest that 2 lateral setae may be typical in this species, katepisternal chaetotaxy is only visible on the left side as the right katepisternum is damaged by pin); linear tuft of setulae under fore coxa dark brown. Area below and behind posterior spiracle bare (without fringe of setulae); meron bare.

Legs: Ground colour of coxae, tibiae, femora and tarsomeres 4 and 5 medium brown, that of tarsomeres 1–3 ivory, but for medium brown apices. Coxae densely silver microtomentose, legs otherwise lightly so. Chaetotaxy black, except for very dense, regularly spaced transverse rows of setulae anteroventrally on apical half of fore tibia and similar setulae on fore tarsomere 1, these dark brown. Fore femur with 4 posterodorsal setae; ctenidial setae 5, relatively long and thick; mid femur with 5–6 anterior setae (5 on right femur, 6 on left); hind femur with single subapical dorsal seta. Mid tibia with 2 strong, 1–2 moderate (1 on right tibia, 2 on left), and several weak apical ventral setae, 1 moderate seta between the large setae, second moderate seta (when present) posterior to the large setae. Row of cuneiform setae present on entire anteroventral margin of mid and hind tarsomere 5.

Wing: Alula relatively narrow. Costal cell, r 1, and anterior half of r 2+3 dark brown infuscate, wing otherwise grey-brown infuscate.

Abdomen: Moderately grey microtomentose with purple-black ground colour. Tergites devoid of maculae and vittae.

Male terminalia: Sternite 5 truncate posteriorly, well sclerotized; tergite 6 moderately sclerotized, small area of desclerotization dorsally on posterior margin; tergite 7 well sclerotized, relatively long, dorsal length ca. 0.5 times dorsal epandrial length; sternite 6 folded over, but not separated by protandrial ridge, broad, more heavily sclerotized proximally on left; sternite 7 separated into right and left portions, right portion length ca. one-quarter length of adjacent portion of sternite 6. Epandrium relatively large, with scattered setulae (in no areas these particularly long), moderately large posterolateral lobe; surstylus laterally articulating and medially fused with epandrium, anterolaterally elongate with flat ventral margin, bending posteriorly around postgonite, with ventrally produced rounded lobe, minutely setulose medially, area adjacent to postgonite slightly concave. Cercus elongate, ventral and dorsal margin flat, angled posteroventrally, longest cercal setulae shorter than long, subequal to longest epandrial setulae. Hypandrium with narrow based, elongate, antrorse dorsobasal lobe, posterior bridge produced ventrally and posteriorly, hypandrial arm with slight dorsal bend at posterior margin of epandrium, with 2 venteromedially oriented setulae proximal to postgonite, broadly fused to opposite hypandrial arm distally; postgonite minutely setulose, with upturned acute apex. Phallapodeme with relatively large, somewhat posteriorly bulging “fan”, margin opposite fan flat basally and convex distally; basiphallus well sclerotized basally, expanded over entire length, relatively stout; distiphallus relatively large, base elongate, bowed ventrally, expanded distally in posterior profile, distiphallus bilobed, lobes subequal in length, left lobe perpendicular to axis of phallus, heavily sclerotized along lateral margin to apex, ventral margin moderately sclerotized, lobe otherwise membranous, apex truncate, lateral corner with well-sclerotized, apically bulbous finger-like projection, medial lobe with 3 membranous apically acute finger-like projections, right lobe in same plane as phallus, with short fine spinules dorsomedially on proximal half, lobe deeply invaginate along left margin, thus composed of 2 valves, these with broadly rounded margins, ventral lobe moderately sclerotized, dorsal lobe weakly sclerotized. Ejaculatory apodeme within basiphallus, elongate, broadening and with small pores basally.

Female terminalia: Unknown.

Type material. Holotype ♂: BRAZIL. Parana: Curitiba , 30 km SE BR277, 6.ii.1990, S.A. Marshall ( MZSP).

Figures

FIGURES 40–42. Curtonotum nigrum Klymko & Marshall, sp. n. 40. Male terminalia, left lateral. 41. Distiphallus, dorsal. 42. Male terminalia, posterior.