Culicoides immaculatus

Bel Li, G. A., Dyce, A. L., Gopurenko, D. & Mitchell, A., 2013, Revision of the Immaculatus Group of Culicoides Latreille (Diptera: Ceratopogonidae) from the Australasian Region with description of two new species, Zootaxa 3680 (1), pp. 15-37 : 22-23

Immaculatus group

Nominate species: Culicoides immaculatus Lee and Reye 1953: 375 .

Diagnosis. Male: the only subgeneric group of Culicoides with unpatterned wings, no SCo on distal three flagellomeres and with parameres possessing abruptly recurved, long, blade-like distal portions that cross ventrally beneath the aedeagus. Female: the only subgeneric group with unpatterned wings, SCo distributed on at least flagellomeres 1,4–8, with two SCo on 5–8 and with sclerotised spermathecal ring more than twice as long as wide.

Description. Female —eyes widely separated, bare or with dense interfacetal hairs. Antenna with flagellomeres evenly clothed in short macrotrichea, 2–8 barrel-shaped, 9–13 cylindrical, elongate, narrowing towards apices; SCo always present on at least 1,4–8, occassionally absent from 4 in C. agas ; usually with two SCo per segment; SCh strong and abundant, basal whorls of 6 and 7 on flagellomeres 2–8, usually present in lesser numbers on some or all of 9–13; at least two STl plus one or two STc on 2–8. Palpus with five segments bearing conspicuous chaetica, 3rd segment usually clavate, base narrow, mid section with pronounced mesal swelling, narrowed beyond a rounded or shelf-like, shallow sensory pit; mouthparts moderately short, cibarium bare. Scutum brown, unpatterned; legs brown, lacking pale bands, hind tibial comb with four spines (five in C. agas ), first from spur longest. Wing unpatterned with costa of medium length; cells r1 and r2 subequal in length, with narrow lumens, with or without a distinct stigmatum over r2; veins fuscous, macrotrichia hair-like. Two ovoid developed spermathecae with distinct sclerotized necks and spermathecal ducts two to four times the length of a single spermatheca. Vestigial spermatheca with a short duct that attaches to one of the other ducts well before the sclerotized tubular neck. Sclerotized neck at least twice as long as wide.

Male —Antenna with flagellomeres 2–10 partially fused and bearing a plume of SCh (reduced in number on 9 and 10 of C. collessi ); SCo present on at least 1,5–8; a pair of STl usually present on at least 1–4; STc present on 1– 6; flagellomeres 11–13 elongate cylindrical with basal whorls of about seven SCh on 11–12 or entire antenna feminized, with plume absent. Palpus similar to female but smaller,with fewer capitate sensilla. Genitalia with ninth tergite variable, apicolateral processes short, absent in most specimens of C. immaculatus , caudal margin convex, with at most a median depression or shallow notch; gonocoxite of moderate size, dorsal and ventral roots long, ventral root with foot-shaped apex; short sector of gonostylus swollen, otherwise narrow, smoothly curved with obtusely pointed tip. Ninth sternite broad, caudomedian excavation broad, very shallow to deep, membrane spiculate. Aedeagus A-shaped, about as long as wide or longer with laterally splayed basal arms, medium to high arch, body smoothly arched; distal process longer than broad, often bifid, sometimes adorned with fine spiculae. Parameres separate, each with strong basal knob extended anteriorly to a blunt tip, stem elongate gradually tapering, lacking ventral lobe, abruptly recurved to long, blade-like distal portions crossing ventrally beneath aedeagus.

Immatures. Unknown.

Larval habitats. Immatures of this group have not been collected but the distribution and habits of adults suggests these species breed in an estuarine habitat.

World distribution. Most species are confined to tropical and subtropical areas of the Australasian Region with C. agas ranging west to the Indonesian archipelago.