Stictochironomus Kieffer, 1919

Konar, Sanghamitra, 2021, A new member of the Stictochironomus caffrarius group from West Bengal, India with emendation of generic diagnosis (Diptera, Chironomidae), Zootaxa 5072 (2), pp. 173-181 : 174

Genus Stictochironomus Kieffer

Stictochironomus Kieffer in Kieffer & Thienemann, 1919: 44; Townes 1945: 77 (as subgenus of Tanytarsus ); Pinder & Reiss 1983: 343, 1986: 354; Cranston et al. 1989: 415; Epler et al. 2013: 436.

Chironomini genus “ B ” Pinder & Reiss, 1983: 350.

Chironomini genus “ F ” Pinder & Reiss, 1986: 364.

Type species: Chironomus pictulus Meigen , by subsequent designation of Townes (1945: 77).

Emended diagnosis. Pupa. Anal comb consisting of robust teeth, or of slender, very long basal teeth and broad, short apical teeth.

Larva. Mentum with 3–4 median teeth.

Remarks. Generic diagnoses of Stictochironomus have been given by Cranston et al. (1989) for the adult, Pinder & Reiss (1986) for the pupa, and Pinder & Reiss (1983) and Epler et al. (2013) for the larva. However, the diagnoses for the pupa and larva should be emended to safely accommodate the Indian species described here.

Although some immatures of Stictochironomus , not associated with the adult, have caused confusion, the Chironomini genus “ B ” of Pinder & Reiss (1983) and the Chironomini genus “ F ” of Pinder & Reiss (1986) are now regarded as concepts for the larva and the pupa, respectively, of the Stictochironomus caffrarius group ( Cranston et al. 1989: 416, Epler 2001: 8.152, Epler et al. 2013: 436, Cranston & Tang 2018: 64). The species group is distinct from the other members of this genus in the larval mentum with 3–4 large median teeth convexly arranged and the pupal anal comb with slender, very long basal teeth and broad, short apical teeth, although it is not separable by the adult morphology. Hitherto, five species of the group have been known in the world: S. polystictus ( Kieffer, 1911) from the Oriental region, S. caffrarius ( Kieffer, 1921) from the Palaearctic and the Afrotropical regions, S. affinis ( Johannsen, 1932) from the Oriental and the Austrasia regions, S. obscurus ( Guha & Chaudhuri, 1983) from the Oriental region, and S. caffrarius group sp. Epler, 2001 from the Nearctic region.

In the Chironomini genus “ B ” of Pinder & Reiss (1983) it has been shown that the larva of the species group has four convexly arranged median teeth, but the larvae of three Oriental species, S. polystictus , S. affinis and S. obscurus , as well as the species described here, possess three median teeth. Epler et al. (2013: 436) wrote, “Larvae with only 3 median teeth (cf. Chernovskii (1949), sub. Stictochironomus “connectens” No. 2) may be aberrant specimens, in which 1 of the 2 small median teeth is reduced.” In the larva of the S. caffrarius group, there is little possibility that the median teeth are reduced or aberrant, since the three or four median teeth are large and arranged in convex row.