Stempellinella coronata Inoue, Kawai, and Imabayashi

Ekrem, Torbjørn, 2007, A taxonomic revision of the genus Stempellinella (Diptera: Chironomidae), Journal of Natural History 41 (21 - 24), pp. 1367-1465 : 1401-1403

Stempellinella coronata Inoue, Kawai, and Imabayashi

Stempellina coronata Inoue, Kawai and Imabayashi 2004, p 143 . Holotype: „ Japan, Hiroshima, Yasuno, Senba, Ohta River , 21 November 2004, E. Inoue. Paratypes: 18 „„ in LAEH [not examined].

Material examined

Japan (VM): 1 „, 3♀♀, Hiroshima, Yasuno, Senba, Ohta River , 21 October 2003, E. Inoue [locus typicus] .

Diagnostic characters

Stempellinella coronata can be separated from other Stempellinella species by the following combination of characters: male imago with AR ca 0.5–0.6; anal point long, thin, with comparatively very weak crests; small median anal tergite setae sometimes present close to anal point base; anal point base with numerous groups of three or four strong microtrichia; lateral anal tergite seta absent; median volsella posteriorly curved, without microtrichia, with fan of simple, anally directed lamellae ( Inoue et al. 2004, Figure 5B ). Female imago with AR 0.25–0.37; VR 1.58–1.70; well-developed vaginal floor, covering ca one-half of vaginal opening ventrally, with setae; seminal capsules small (diameter ca half of notum length); spermathecal ducts longer than notum excluding rami.

Redescription

Adult male is thoroughly described by Inoue et al. (2004), and only a few additional observations are added here: hypopygium ( Figure 11A ) without lateral seta on anal tergite, with two median setae and ca 16 apical setae including lateral setae on anal point.

Adult female (n 5 3, unless otherwise stated). Total length 1.0–1.2, 1.1 mm; wing length 0.85– 0.86, 0.86 mm.

Colour: as male.

Head: as male, except antenna ( Figure 11B ) with five flagellomeres, ultimate flagellomere 45–51, 48 Mm long, AR 0.25–0.37, 0.30; lengths of palpomeres (in Mm): 18–21, 19; 18–21, 19; 45; 60–66, 63; 66–93, 80. Clypeus with 12–19, 15 setae.

Thorax: scutal tubercle absent; acrostichals 10–13, 11; dorsocentrals 5–6; humerals 1–2; prealars 1; scutellars 4–6; halterals 5.

Wing: as male. VR 1.58–1.70, 1.62.

Legs: as male. Fore tarsi were missing on all examined specimens.

Genitalia ( Figure 11C ): tergite IX slightly triangular, about 36 Mm long; sternite VIII with 12–16, 14 setae, of which three or four are placed on vaginal floor; vaginal floor large, covering ca one-half of vagina ventrally; gonapophysis VIII single lobe with long posteromedially directed microtrichia; gonocoxapodeme slightly curved, reaching lobe of gonapophysis VIII; coxosternapodeme well developed with large lateral lobe. Notum including rami 114–120, 116 Mm long, notum alone ca 60 Mm long. Seminal capsules ovoid, diameter 30–36, 34 Mm with 75–105, 80 Mm long spermathecal ducts. Postgenital plate subtriangular. Cercus 36–39 Mm long.

Pupa and larva. Unknown.

Remarks

Females were associated with males by 98.7–100% similarity in 666 base pairs of the mitochondrial COI gene.

Stempellinella coronata is most similar to the Afrotropical S. chambiensis and the Palaearctic S. edwardsi (see Remarks under S. chambiensis ). The species has been recorded so far only from Japan where it inhabits clear, unpolluted pools in the upper to mid reaches of the Ohta River system ( Inoue et al. 2004). Although immature stages are unknown, the larvae are likely to build small transportable cases of sand grains and organic particles like the remainder of the species in the genus.

Figures

Figure 5. Stempellinella brevis (Edwards), imagines. (A–F) Male: (A) head; (B) antennal flagellum; (C) wing; (D) fore, mid, and hind tibiae; (E) hypopygium; (F) superior, median, and inferior volsellae. (G, H) Female: (G) antenna; (H) genitalia.

Figure 11. Stempellinella coronata Inoue, Kawai and Imabayashi, imagines. (A) Male: hypopygium. (B, C) Female: (B) antennal flagellum; (C) genitalia.