Polypedilum (Tripodura) prolixus, Mukherjee & Ray & Mukherjee & Naskar & Banerjee, 2024

Mukherjee, Bindarika, Ray, Namrata, Mukherjee, Arka, Naskar, Atanu & Banerjee, Dhriti, 2024, First report of acifer group of the subgenus Tripodura Townes (Diptera: Chironomidae: Polypedilum) from India, with a new species and updated world checklist, Zootaxa 5512 (4), pp. 531-552 : 533-536

Polypedilum (Tripodura) prolixus sp. n.

GenBank accession number. PQ074114

Material examined. Holotype male, labelled ‘ Polypedilum (Tripodura) prolixus sp. n., India, West Bengal, Kalimpong , [27.0601° N, 88.4666° E], 24.iii.2024, Coll. T. Roy’ . Paratype 7 males, same data as holotype .

Diagnostic characters. The adult males of this species can be diagnosed by following combination of characters: wing with markings, squama with less setae, presence of elongated and sickle shaped superior volsella with a submedial seta, parallel shaped and cylindrical inferior volsella and distally spatulated anal point.

Etymology. The name ‘ prolixus ’, a Latin word, refers to the apically expanded anal point.

Male (n=8)

Total length 2.00–2.35, 2.18 mm. Wing length 1.28–1.38, 1.33 mm. Costal length 1.20–1.33, 1.23 mm. Antennal length 0.63–0.74, 0.68 mm.

Colouration. Whole body is brown in colour.

Head. Head width 400–475, 438 µm. Temporal Setae 5–8 (IV 2, OV 2–4, Po 1–2). Clypeal setae 13–14. Frontal tubercles absent. Eyes bare, with dorsomedial extension of 110–115, 113µm. Ultimate flagellomere 225–310, 267 µm long;AR 0.55–0.77, 0.66. Length of palpomeres (I–V) (µm): 25–30, 27.5: 25–30, 27.5: 70–85, 77.5: 85–98, 91.5: 100–138, 119. CA 0.61–0.67, 0.64.

Thorax. Acs 5, Dcs 7–8, Pa 4, and Scts 2, others not countable.

Wing ( Fig. 1A ). VR 1.30–1.47, 1.39. R 1 with 10–17 setae, R 4+5 with 8–10 setae. Brachiolum with 1 seta. Squama fringed with 2–4 setae. FCu distinctly distal to RM. Anal lobe moderately developed. Wing markings present, one near Cu 2 and another one down to anal lobe.

Legs. Fore tibial scale triangular cone-like ( Fig. 1B ), well developed, 30–35, 32.5 µm long. Mid and hind tibiae with unspurred anterior comb narrowly separated from posterior comb with spur. Mid leg with 1 tibial spur, 35–40, 38 µm long, and each comb with 11 and 22 teeth. Hind leg with 1 tibial spur, 35–40, 38 µm long and each comb with 13 and 24 teeth. Lengths (µm) and proportions of legs are shown in table 2.

Hypopygium ( Figs. 1C–D , 2A–B ). Anal tergite band ‘V’ shaped, not meeting medially. Tergite IX with 2–3 median setae. Anal point moderately long, 60–63, 61 µm, spatulated distally and a ‘V’ shaped basal ridge present. Posterior tergite IX with projections lateral to anal point, having 2–3 setae. Superior volsella 40–45, 43 µm long, elongated, sickle shaped, bearing submedial seta (15–20, 18 µm long) and microtrichia at apex, and having a distinct base. The width of superior volsella reduced to tapering off after setal base in some specimens ( Fig. 2B ). Inferior volsella 70–75, 72.5 µm long and 13–18, 15 µm wide, cylindrical shaped with strong setae apically and subapically. Transverse sternapodeme 25–28, 26 µm long; longitudinal sternapodeme 65–72, 69 µm long. Gonocoxite 90–100, 95 µm long. Gonostylus 105–112.5, 108.75 µm long, five setae along inner margin and bearing one seta at apex. HR 0.80–0.88, 0.84; HV 1.90–2.1, 2.

Remarks. The combination of characters of the new species: i. tergite IX with strong projection on each side of the anal point, ii. squama with less than five setae, iii. anal point distally broad, iv. apical projection of superior volsella present, v. base of R 4+5 cell without spot, confirm the emplacing within the acifer species group.

The new species is closely similar with P. (T.) falcatum in the presence of almost similar wing marking, nearly equal range of LR; but it differs in the number of thoracic setae (Dcs 9–13, 11; Acs 12–17, 14; Scts 5–9, 6 setae in P. (T.) falcatum, while Acs 5; Dcs 7–8; and Scts 2 in the new species), shape of anal point (broad anal point with a V shaped ridge in P. (T.) falcatum while spatulated anal point with a longitudinal ridge present in the new one), and inferior volsella (narrow and apically bilobed inferior volsella present in P. (T.) falcatum while the inferior volsella is cylindrical shaped in the new species) along with other morphometric variation.

Distribution. India, West Bengal (present record).

Figures

FIGURES 1A–D. Adult male of Polypedilum (Tripodura) prolixus sp. n. A. Wing, B. Fore leg, C. Hypopygium (dorsal view), D. Hypopygium (ventral view).

FIGURES 2A–B. Adult male of Polypedilum (Tripodura) prolixus sp. n. A. Hypopygium, scale 0.01 mm, B. Different shape of superior volsella.