Culicoides isoregalis Majumdar & Das Gupta

Sarkar, Ankita, Banerjee, Paramita, Sinha, Shuvra Kanti & Mazumdar, Abhijit, 2023, A taxonomic revision of the Indian species of the ‘ Aterinervis’ group of Culicoides Latreille Subgenus Hoffmania Fox (Diptera: Ceratopogonidae), Zootaxa 5258 (4), pp. 405-428 : 410-412

Culicoides isoregalis Majumdar & Das Gupta

( Fig 3a–i )

Culicoides isoregalis Majumdar & Das Gupta , in Majumdar, Das Gupta & Gangopadhyay 1997: 28; Majumdar 1972: 143–147; Nandi 2014: 88–90

Material examined. Holotype (1 ♀), Darjeeling Govt. College, August, 1968, Coll. P.K. Chaudhuri; Allotype (1 ♁), Darjeeling Govt. College, May, 1968, Coll. P.K. Chaudhuri.

Diagnosis. The only species in the Aterinervis group with the following suite of characters: Poststigmatic pale spot not extending posteriorly to touch but not cross vein M 1; distal pale spot in cell m 1 narrow, elongate; triangular pale spot in cell cua 1; anal cell with elongate distal pale spot; posterior margin of tergum IX ending just before the apex of the gonocoxite.

Female.

Head ( Figs. 3a, 3b and 3c ). Antenna with SCo on flagellomeres 1, 9–13. Third palpal segment slender, medially swollen bearing capitate sensilla without sensory pit; second segment slender, first, fourth, fifth segments short, stout.

Thorax. Scutum pale brown; lateral margin dark brown with two dark lateral, pale median streaks; postscutellum dark brown.

Legs ( Figs. 3d and 3e ). Brownish; fore femora with pale apical and mid femora with basal and apical pale bands, fore and mid tibiae with basal pale bands, hind femora with pale basal bands, hind tibia with pale basal and apical bands; hind tibial comb with 6 spines, second longest; spur tip frayed; claws equal.

Wing ( Fig. 3f ). Pale spot over r-m crossvein crossing vein M; distal portion of 2 nd radial cell included in pale triangular poststigmatic pale spot that does not extend to vein M 1; apical pale spot in cell r 3 not reaching wing margin; cell m 1 with two pale spots, distal one elongate, not reaching wing margin; distal pale spot in cell m 2 broadly reaching wing margin; triangular pale spot in cell cua 1 expanded at wing margin; dark spot parallel with vein CuA 2; dark marking in anal angle; distal pale spot broadly tapering to posterior wing margin. Macrotrichia numerous on distal part of the wing.

Abdomen ( Fig. 3g ). Dark streaks on terga; spermatheca two, subequal, ovoid, well developed, brown with sclerotized, oblique necks; rudimentary spermatheca present; small ring present.

Male. Similar to female with usual sexual differences.

Genitalia ( Figs. 3h and 3i ). Caudomedian excavation shallow, U shaped. Tergum IX without apicolateral processes, posterior margin of tergum IX ending before the apex of the gonocoxite; gonocoxite with well developed dorsal root; gonostylus elongate, medially curved with blunt tip. Aedeagus V shaped with small, bent basal arms, stem broad at basal half, narrow end. Parameres with stout basal arms, stem broad basally.

Immatures. Unknown

Larval habitat. Unknown

Distribution. India (Darjeeling, West Bengal)

Remarks. C. isoregalis is similar to C. subregalis in possessing dark area at anal angle, pale spot over r-m crossvein narrow. It differs as it possesses an elongate distal pale spot in cell m 1, triangular pale spot in cell cua 1 and a pale brown scutum. These two species share many similarities and have overlapping morphometric data so may in fact be a single, variable species but this requires further validation to confirm. C. regalis is also similar to C. isoregalis but differs in antennal ratio, palpal ratio and in the number of mandibular teeth ( Table 1 ), presence of pale spot over r-m crossvein broad, pale area of wing base extending to posterior wing margin of anal cell and distal pale spot of anal cell bilobed.

Figures

FIGURE 3. Culicoides isoregalis. a) head; b) mandibular teeth; c) maxillary palp; d) hind tibial spines; e) mid tarsis; f) wing; g) spermathecae with ring; h) male genitalia and i) paramere