Monopelopia (Monopelopia) obscurata, Mondal & Mukherjee & Hazra, 2022

Mondal, Debarshi, Mukherjee, Tuhar & Hazra, Niladri, 2022, TWO NEW SPECIES OF MONOPELOPIA FITTKAU, 1962 FROM FORESTS IN INDIA ALONG WITH A KEY TO ADULT MALES OF ORIENTAL AND PALEARCTIC SPECIES (DIPTERA: CHIRONOMIDAE) Abstract, CHIRONOMUS Journal of Chironomidae Research 35 (35), pp. 32-42 : 35-41

Monopelopia (Monopelopia) obscurata sp. n.

https://zoobank.org/ 0A5C24CA-B5A8-489A-AC6A-B5C3F69C385D

Type Material. Holotype male with larval and pupal exuviae (reared), labelled as ‘ Monopelopia obscurata sp. n. Mondal, Mukherjee and Hazra , India, West Bengal, Suntaley khola (27.01, 88.78), 03.VII.2019, Coll. D. Mondal’.

Diagnosis. The new species can be separated from other members of the subgenus Monopelopia by having the following combination of characters: Male. AR 1.46; wing uniformly covered with dense macrotrichia; darkened r-m cross vein; hind tibial comb with 6 setae; T IX with 2 dorsolateral setae on each side. Pupa. Thoracic horn without acute apical projection, plastron plate occupying distal fifth of thoracic horn, L/ W 6.1. Larva. Pecten hypopharyngis with 4 teeth, posterior parapod with one darkened strongly curved claw with 5 inner teeth.

Etymology. The name ‘ obscurata ’ is of Latin origin meaning ‘darkened’ referring to darkened cross-vein, to be treated as adjective.

Description

Male imago (n = 1). Total length 1.62 mm. Wing length from arculus 1.16 mm, width 0.33 mm, L/ W 3.5. Total length / WL 1.39. WL / Length of forefemur 2.44.

Colouration. Head brown. Antenna pale brown, maxillary palp light brown. Thorax brown, vittae dark, antepronotum dark, wings uniform pale except, dark brown cross vein, legs pale brown, abdomen entirely pale brown. Hypopygium brown.

Head. Eyes bare, dorsomedian extension 73.6 µm. Apical seta of antenna ( Fig. 3B ) 34.5 µm, AR 1.46. Temporal setae 9, uniserial. Clypeus with 28 setae. Length of palpomeres I-V (µm): 27.6: 34.5: 110.4: 115: 128.8. CA 0.66. CP 0.97.

Thorax. Scutal tubercle and pit absent. Antepronotum with 2 lateral setae; acrostichals 32, irregularly biserial; dorsocentrals 19 each side, biserial anteriorly and uniserial posteriorly; prealars 5; scutellars 9.

Wing ( Fig. 3A ). Wing membrane with dense macrotrichia; squama with 14 setae; brachiolum with 2 setae; vein lengths (µm): C 980, Sc 475, R 1 375, R 4+5 550, M 1+2 700, R 4+5 ending long before M 1+2, anal lobe round, poorly developed; CR 0.84; VR 0.86.

Legs. Tibial spurs as in Fig. 3C . Ti I spur 39.1 µm long; Ti II spur 41.4 µm long; Ti III spur 52.9 µm long; hind tibial comb with 6 setae. Length (µm) and proportions of leg segments as in Table 3 .

Abdomen. T IX with 2 dorsolateral setae on each side.

Hypopygium ( Fig. 3D ). Anal point conical in shape with broad base. Gonocoxite 135 µm long, 51 µm wide, L/ W 2.64. Gonostylus simple, curved inwardly, 64.4 µm long, basal width 18.4 µm, Gs/ Gc 0.75. Megaseta 13.8 µm long. Phallapodeme 48.3 µm long; HR 2; HV 2.53.

Pupa (n = 1)

Colouration. Exuviae pale yellow without apparent pattern.

Total length. 2.58 mm.

Cephalothorax. Frontal apotome triangular. Wing sheath 968 µm long. Thoracic horn ( Fig. 4A ) tubular, 285 µm long, 46.7 µm broad without apical spine, surface with scattered broad–based spinules, ThR 6.1, plastron plate egg-shaped, 142 µm long, 84 µm wide occupying 0.38 length of horn; respiratory atrium tubular, about a third of the width of Th, walls thick with narrow duct-like lumen, basal lobe reduced. Dc 1 112 µm long, Dc 2 111 µm long and Sa 86 µm long.

Abdomen ( Figs. 4b–c ). Scar on tergite I 128 µm long, elongate and without pigmentation. Tergites I –VIII without shagreen, 4 LS setae on tergite VII located at 0.27, 0.47, 0.62 and 0.91 respectively from anterior margin; tergite VIII with 5 LS setae located 0.36, 0.50, 0.73, 0.87 and 0.98 respectively from anterior margin. Anal lobe 320 µm long, 265 µm wide; L/ W 1.2, outer margin with 6 spinules, male genital sacs 351 µm long, 187 µm wide, not extending beyond apices of anal lobes, G/F 1.09, L/ W 2.70.

Fourth instar larva (n = 1)

Total length 3.2 mm.

Colouration. Pale yellow.

Head. Cephalic index 0.49. Antenna ( Fig. 5A ). AR 3.54; length of antennal segments I–IV (µm): 253, 59.8, 4.6, 6.9; ring organ situated 0.54 from base; blade 55 µm long, accessory blade 51 µm long. Mandible ( Fig 5B .). 69 µm long; apical tooth 23 µm long, basal tooth 16.1 µm long; A1/MD 3.67. Maxilla ( Fig 5C .). Basal segment 32.2 µm long; ring organ situated 0.46 from base. Mentum and M appendage ( Fig. 5D ). Two small dorsomental teeth reduced, 4 µm long, on each side of base. Pseudoradula 69 µm long with distally coarser granulation. Ligula ( Fig. 5E ). 54 µm long, with 5 subequal teeth forming slightly concave margin; paraligula 34.5 µm long, bifid. Pecten hypopharyngis with 4 teeth.

Cephalic chaetotaxy ( Fig. 5F ). Dorsal seta. S7 and S8 closely placed each other and along with S5 formed acute angle. Ventral seta. VP and SSm directly medial; S 10 further anterolateral; S 9 even further anteromedial.

Body. Anal tubules cylindrical, 94.3 µm long, 25.3 µm wide; supra-anal setae 264.5 µm long. Procercus 88 µm long and 33 µm wide with 7 apical setae. Length of sub basal setae of posterior parapod 128 µm. total number of setae 4; 2 long claws each with 4 and 2 inner teeth, short claw one with 2 inner teeth and another strongly curved claw with 4 inner teeth ( Fig. 5G ).

Remarks

A comparison among M. mongpuense , M. recta , M. adeliae , M. macunaima , M. edentata and M. obscurata sp. n, is given in Table 2 and Table 4 .

Distribution and bionomics. M. obscurata is so far known only from India.

Suntaleykhola is a dense forested area with temperate climate, occupying the eastern fringes of the Himalayan foothills. The larva was collected from a marshy area at the bank of a small stream.

Figures

Figure 3. Male of Monopelopia (Monopelopia) obscurata sp. n. A, wing, scale: 1 mm; B, ultimate flagellomere, scale: 30 µm; C, tibial spurs, scale: 10 µm; D, hypopygium, scale: 100 µm.

Figure 4. Pupal exuvia of Monopelopia (Monopelopia) obscurata sp. n. A, thoracic horn, scale: 100 µm; B, abdominal TI-TVII, scale: 1 mm; C, tergite VIII and anal lobe, scale: 100 µm.

Figure 5. Larva of Monopelopia obscurata sp. n. A, antenna, distal end, scale: 100 µm; B, mandible, scale: 10 µm; C, maxillary palp, scale: 10 µm; D, mentum and m appendage, scale: 10 µm; E, ligula and paraligula, scale: 10 µm; F, cephalic chaetotaxy; G, claws of posterior parapod, scale: 10 µm.