Saetheria circinata, Mukherjee & Hazra, 2023

Mukherjee, Bindarika & Hazra, Niladri, 2023, Taxonomic studies on Harnischia complex from India (Diptera: Chironomidae), Zootaxa 5278 (2), pp. 239-263 : 251-253

Saetheria circinata sp. n.

GenBank Accession No. OP683428

urn:lsid:zoobank.org:act:60F40CC2-CCA8-44E2-B256-7CB9E40BC76F

Material examined. Holotype male, labelled ‘ Holotype Saetheria circinata sp. n., India, West Bengal, Purba Barddhaman [23.2393° N, 87.8512° E], 04.ii.2020, Coll. N. Hazra’ . Paratype 1 male, same data as holotype, 25.vi.2020, Coll. N. Hazra. Paratypes 2 males, same data as holotype, 15.ii.2021, Coll. N. Hazra. Paratype 1 male, same data as holotype, 14.vi.2021, Coll N. Hazra . Paratype 1 male, same data as holotype, 19.xi.2021, Coll. N. Hazra.

Diagnostic characters. The distinguished features of new species are as follows: apically slightly broadened anal point with a median ridge, Y shaped anal tergite band, anal tergite band and nearly triangular shaped ventral lobe of superior volsella.

Etymology. The name ‘ circinata ’, originated from a Latin word ‘ circinatus ’, refers to circular dorsal lobe of superior volsella.

Male (n=6)

Total length 2.75–2.8, 2.775 mm. Wing length 1.7–1.85, 1.77 mm. Costal length 1.65–1.7, 1.67 mm. Antennal length 0.82–0.85, 0.835 mm. Colouration. Thorax with dark brown marking; leg and abdomen yellowish brown.

Head. Head width 450–460, 455 µm. Temporal setae 8–9 (IV 4–5, OV 3–4, Po 0–1). Clypeal setae 12. Frontal tubercles present. Eyes bare with dorsomedial extension of 130–140, 135 µm. AR 1.2–1.41, 1.30; ultimate flagellomere 460–480, 470 µm long. Palpomere lengths (I–V) (µm): 23–25, 24: 30: 80.5–82, 81.25: 103.5: 149.5– 152, 150. CA 0.54–0.55, 0.545.

Thorax. Scutal tubercle absent. Ac 8, Dc 7, Pa 3, Scts 2–3.

Wing ( Fig. 4A ). VR 1.14–1.16, 1.15. R 1 and R 4+5 bare. Brachiolum with 1 seta. Squama with 7 fringed setae. FCu distinctly distal to RM. Anal lobe moderately developed.

Legs. Fore tibia with 2 setae. Mid legs with 2 tibial spurs; 16 µm and 18.4 µm long with 22–26 lateral teeth. Hind leg with 2 tibial spurs; 18.4 µm and 20.7 µm long with 29–32 teeth. Lengths and proportions of leg segments shown in table IV.

Hypopygium ( Figs. 4B–D ). Anal tergite band Y shaped. Anal point slightly expanded apically, 37–40, 38.5 µm long with a median ridge like appearance. Laterosternite IX with 3 setae on each side of anal point. Longitudinal and transverse sternapodeme 75–78, 76.5 µm and 73.5 µm long respectively. Superior volsella 55–58, 56.5 µm long and 25.3 µm wide, nearly triangular in shape, consisting of dorsal and ventral lobe, dorsal lobe having roughly circular base (23 µm long) with digitiform projection (27–28 µm long) while ventral lobe nearly triangular shaped bearing 2 setae (1 seta on heel and another one placed subapically). Inferior volsella with a rounded apical part covered with microtrichia. Gonocoxite 122–126, 124 µm long. Gonostylus 126.5–131, 128.75 µm long. HR 0.96–0.97, 0.965. HV 2.18– 2.29, 2.235.

Distribution. India, West Bengal.

Remarks. Presence of roughly bilobed superior volsella having digitiform projection on dorsal lobe, Y shaped anal tergite band and spatulated anal point confirm the positioning of new species into genus Saetheria Jackson. The new species closely related with S. digitata Yan et al., 2011 in having more or less similar gonostylus and dorsal lobe of superior volsella but presence of triangular like ventral lobe of superior volsella with 1 seta at apical end and somewhat apically spatulated anal point can segregate the new species from S. digitata .

Figures

FIGURE 4. Adult male Saetheria circinata sp. n. A. Wing, B. Hypopygium (dorsal), C. Hypopygium, scale 0.01 mm, D. Superior volsella, scale 0.01 mm.