Culex ( Eumelanomyia ) hayashii Yamada, 1917

3. Culex ( Eumelanomyia) hayashii Yamada, 1917 View in CoL

A total of 39 specimens (1 F with LePe, 1 M, 35 L) of Cx. hayashii were collected from a cement tank and stream pools in Mawsmai, East Khasi Hills, Meghalaya State ( 25.246460 N; 91.731046 E, 1149 m a.s.l) on 01.I.2024. Culex hayashii was originally described from Japan and has also been reported from Korea, the Ryukyu Islands, Taiwan and the former U.S. S.R. The specimens collected in the present study were examined and compared with the illustrations and descriptions provided by Sirivanakarn (1972) and Tanaka et al. (1979).

Diagnosis. Within the Tenuipalpis Subgroup , Cx. hayashii closely resembles Cx. tenuipalpis and Cx. richei in possessing a long male maxillary palpus, approximately 0.5 times the length of the proboscis. However, it can be distinctly separated from Cx. tenuipalpis based on characters of the male genitalia, pupa and larva. In Cx. hayashii , the gonostylus lacks the 2–4 very small setae typically found in the basal half; the lateral plate of the phallosome is somewhat pointed apically and bears fewer denticles, all confined to the inner tergal surface ( Fig. 2h). Nevertheless, variation in the number and arrangement of denticles has been reported by Tanaka et al. (1979). In contrast, Cx. tenuipalpis exhibits 2–4 very small setae in the basal half of the gonostylus, and the lateral plate of the phallosome bears approximately 20 strong denticles. The male of Cx. hayashii can be distinguished from Cx. richei by the presence or absence of a submarginal seta on the gonocoxite ( Fig. 2g), whereas Cx. richei possesses 3–5 submarginal setae in this region.

In the pupa of Cx. hayashii , seta 5-IV is 3-branched and seta 6-III–VI has four branches, whereas in Cx. tenuipalpis seta 5-IV and seta 6-III–VI are bifid. Larval characteristics of Cx. hayashii are illustrated in Fig. 2i–l: Seta 6-III–VI has 3 or 4 branches ( Fig. 2j) and the siphon is slender, not curved upwards, with siphonal setae that are weaker and shorter, particularly the first five setae, which measure about 2‒3 times longer than the diameter of the siphon at the point of attachment ( Fig. 2k). In comparison, Cx. tenuipalpis larvae have seta 6-III–VI double and the siphon is strongly tapered and curves upwards distally, with the first 3 or 4 setae 4 or 5 times longer than the diameter of the siphon at the point of attachment.