Culex ( Eumelanomyia ) macrostylus Sirivanakarn & Ramalingam, 1976

2. Culex ( Eumelanomyia) macrostylus Sirivanakarn & Ramalingam, 1976 View in CoL

A total of 58 specimens (9 F, 7 M, 5 MG, 6 Le, 25 L) of Cx. macrostylus were examined. Among these, two females and one male were associated with larval and pupal exuviae. Seven females and four males were collected resting inside man-made sandy caves, while others were reared from immature stages collected between July 2022 and January 2024 from diverse habitats, including turbid pools inside man-made caves, stream pools, a cement tank, rock pools and a swamp. Collections were made near Jarain in the Jaintia Hills ( 25.389822 N; 92.142540 E, 1,314 m a.s.l.; 25.389945 N; 92.147489 E, 1,295 m a.s.l.; 25.246460 N; 91.731046 E, 1,149 m a.s.l.) and Mawsmai in the Khasi Hills ( 25.505226 N; 91.812965 E, 1,644 m a.s.l.), Meghalaya State, India. Specimens were compared with original descriptions of Sirivanakarn & Ramalingam (1976) and Harbach & Rattanarithikul (1988). Culex macrostylus was previously known only from Malaysia.

Diagnosis. The adult female of Cx. macrostylus is illustrated in Fig. 2d. Males are distinguishable from other members of the Tenuipalpis Subgroup ( Mochthogenes Group, subgenus Eumelanomyia ) by the following morphological features: A conspicuously large, broad gonocoxite; a subapical lobe with one prominent flattened blade-like seta and about 10 lanceolate setae; and a large, goose-head-shaped gonostylus ( Fig. 2e). Based on male, female and larval characteristics, Cx. macrostylus is placed within a complex of six closely related species: Culex tenuipalpis Barraud, 1924a , Cx. richei Klein, 1970 , Cx. hayashii Yamada, 1917 , Cx. hackeri Edwards, 1923 , Cx. kiriensis Klein & Sirivanakarn, 1970 and Cx. oresbius Harbach & Rattanarithikul, 1988 . Among these species, Cx. macrostylus resembles Cx. hackeri , Cx. kiriensis and Cx. oresbius by its short male maxillary palpus, approximately 0.2 times the length of the proboscis, and the broad oval shape of the lateral plate of the male phallosome. However, Cx. kiriensis has a lateral plate that is distinctly tapered into a pointed or blunt apex. Culex macrostylus differs by having a distinct subapical lobe and a broader lateral plate.

Larvae are identified by a strongly tapered siphon that curves upward distally and bears 7 pairs of setae ( Fig. 2f). The setae are 4–5 times wider than the diameter of the siphon at the point of attachment, resembling Cx. tenuipalpis and Cx. hackeri , but differing from Cx. hayashii and Cx. richei , which have slender siphons. Culex macrostylus larvae differ from Cx. tenuipalpis and Cx. hackeri by a stronger, subequal seta 8-P, triple-branched seta 6-III–VI seta and more siphonal setae.

Harbach & Rattanarithikul (1988) noted that Cx. macrostylus and Cx. oresbius differ in features of the male genitalia but not in characteristics of the larval and pupal stages. They proposed that the two species may represent geographical variants of a single species, as Cx. macrostylus is known from Malaysia and Cx. oresbius from Thailand, approximately 1,800 km apart.