Demicryptochironomus (Demicryptochironomus) praeacutus Mukherjee et Hazra, 2022

Mukherjee, Bindarika & Hazra, Niladri, 2022, Two new species of Demicryptochironomus Lenz, 1941 from India with tentative phylogenetic relationship and a revised world key to known males (Diptera: Chironomidae), Zootaxa 5175 (1), pp. 88-100 : 90-92

Demicryptochironomus (Demicryptochironomus) praeacutus Mukherjee et Hazra , sp. n.

urn:lsid:zoobank.org:act:F48E2EBE-70ED-4E3F-B96B-231DD922E9F3

GenBank Accession No. ON898600

Material examined. Holotype male, labelled ‘ Holotype Demicryptochironomus (Demicryptochironomus) praeacutus sp. n., India, Assam, Kohora [26.15° N, 91.79° E], 16.iv.2022, Coll. B. Khan’ . Paratypes 2 males, same data as holotype, labelled ‘ Paratype Demicryptochironomus (Demicryptochironomus) praeacutus sp. n. Paratype 1 male, labelled ‘ Demicryptochironomus (Demicryptochironomus) praeacutus sp. n., India, West Bengal, Burdwan [23.2441319° N, 87.8368799° E], 17.ix.2019, Coll.B. Mukherjee’ . Paratype 1 male, labelled ‘ Demicryptochironomus (Demicryptochironomus) praeacutus sp. n., India, West Bengal, Burdwan [23.2393° N, 87.8512° E], 14.x.2019, Coll. B. Mukherjee’ . Paratypes 4 males, labelled ‘ Demicryptochironomus (Demicryptochironomus) praeacutus sp. n., India, West Bengal, Burdwan [23.2393° N, 87.8512° E], 16.vii.2020 & 10.i.2021, Coll. N. Hazra’ .

Diagnostic characters. The adult male is distinguished from other species of the genus Demicryptochironomus by the presence of tapered gonostylus with pointed apex and bilobed or trilobed superior volsella having clubbed apical end.

Etymology. The name “ praeacutus ’’, a Latin word, refers to the sharply pointed gonostylus at apex.

Male (n=9)

Total length 2.8–3.2, 3 mm. Wing length 1.65–1.7, 1.675 mm. Costal length 1.57–1.62, 1.59 mm. Antennal length 0.88–0.91, 0.895 mm.

Colouration. Thorax yellowish brown, leg colour light brown, abdomen yellow to light brown.

Head. Head width 570–580, 575 µm. Temporal setae 7–11 (IV 2, OV 5–6, Po 0–2). Clypeal setae 12–15. Frontal tubercles present, 6.9 µm long. Eyes bare with dorsomedial extension of 119–130, 124.5 µm. Ultimate flagellomere 570–590, 580 µm long; AR 1.7–1.93, 1.82. Length of palpomeres (I–V) (µm): 25–27.6: 30: 94–97.5: 134.6–138: 165.6. CA 0.64–0.66, 0.65.

Thorax. Acrostichals 10–12, dorsocentrals 24, prealars 3, supraalars 2 and scutellars 9–10.

Wing ( Fig. 1A ). VR 1.10–1.11. R with 36 setae, R 4+5 with 26 setae. Brachiolum with 2 setae. Squama with 6 fringed setae. FCu distinctly distal to RM. Anal lobe moderately developed.

Legs. Fore tibia with 2–3 setae. Mid legs with 2 tibial spurs; 18.4–20.7 µm and 23 µm long, comb with 28–36 teeth. Hind leg with 2 tibial spurs; 25.3 µm and 27.6–29.9 µm long, comb with 50–52 teeth. Lengths (µm) and proportions of legs shown in table 1.

Hypopygium ( Figs. 1B–D ). Anal tergite band V shaped. Anal point slender, parallel sided; 46–48, 47 µm long, 6.9 µm wide.Anal point bearing 2–3 lateral setae on each side. Tergite IX with 16–18 setae. Transverse sternapodeme 64.5–69, 66.75 µm long. Superior volsella ( Fig. 1D ) nearly bilobed or trilobed, apically pommel in shape, bearing 3 long setae and microtrichia; 46 µm long and 11.5 µm wide at apex. Inferior volsella absent. Gonocoxite 115–119, 117 µm long. Gonostylus 126.5–131, 128.75 µm long, tapered apically with pointed apex. HR 0.91–0.94, 0.925; HV 2.4–2.7, 2.55.

Distribution ( Fig. 2 ). West Bengal and Assam, India (present record).

Remarks. Characters such as V shaped anal tergite band, absence of inferior volsella, bilobed or trilobed superior volsella and presence of frontal tubercles assert the positioning of this new species in Demicryptochironomus (Demicryptochironomus) . Parallel sided anal point without ridge present in both the new species and D. (D). zairensis Lehman, 1979 but they differ in the shape of superior volsella and gonostylus.

Figures

FIGURES 1. Adult male Demicryptochironomus (s. str.) praeacutus sp. n. A. wing, B. hypopygium, C. hypopygium scale 0.01 mm, D. superior volsella scale 0.01 mm.

FIGURE 2. Distribution map of Demicryptochironomus (s. str.) praeacutus sp. n.