Culicoides cornatus, Chatterjee & Pal & Hazra, 2022

Chatterjee, Somnath, Pal, Gouri Sankar & Hazra, Niladri, 2022, Descriptions of two new species of Culicoides Latreille from Sundarbans, India with an adult key to the ornatus species group of the Oriental region (Diptera, Ceratopogonidae), Evolutionary Systematics 6 (1), pp. 89-102 : 89

Culicoides cornatus sp. nov.

Figs 2A-H , 3A-E

Type material.

Holotype: male, labelled as 'Holotype Culicoides cornatus Chatterjee, Pal and Hazra, India, West Bengal, South 24 Parganas, Balibazar [22°08'88"N, 88°75'72"E], 16.04.2019, Coll. S. Chatterjee’ (NZCI). Paratypes: 1 male and 3 females, data as holotype (BUENTD).

Diagnosis.

Eyes with interfacetal hair, wing with inconspicuous pale marking, pale spot on cell r3 occupying greater than half of the entire cell, tips of veins pale; horn shaped appearance of anterior portion of parameres.

Description.

Female (n = 3). Head. Brown, eyes with interfacetal hair (Fig. 3C ), separated by distance of 1-2 ommatidia; frontovertex with 29-31 SCh; antenna pale; length ratio of antennal segments (I-XIII): 21-22 (21.5): 10: 10-11 (10.5): 9-10 (9.5): 10: 9-10 (9.5): 9: 10: 20: 24-25 (24.5): 24-25 (24.5): 25: 31-33 (32); AR 1.40-1.39 (1.395); SCo (Fig. 2B ) present on antennal segments I-XII; only absent in segment XIII; maxillary palpus (Figs 2A , 3D ) pale, hairy; length ratio of palpal segments (I-V): 10: 19: 28: 9: 10; PR 2.15. Palpal segment III moderately swollen with subapically round, shallow sensory pit with numerous capitate sensilla restricted in sensory pit; SCh numbers in palpal segments (I-V): 1: 4: 6: 3: 6. Mandible with 17 teeth. P/H 0.58.

Thorax (Fig. 3B ). Brown in colour.

Wing (Fig. 3A ). Wing with inconspicuous pale marking; costa moderately long; cell r2 moderately broad with distinct lumen; macrotrichia sparse; wing length 0.90-0.92 (0.91) mm, width 0.44-0.46 (0.45) mm; CR 0.68-0.69 (0.685); second radial cell entirely in dark region; pale spot over r-m cross vein moderately large, extending from vein M1 to costal margin; post stigmatic pale spot obliquely placed with slight medial constriction; cell r3 with distal large pale spot occupying greater than half of cell r3 and broadly touching wing margin; cell M1 with two pale spots, distal one touching wing margin; anal cell with one medially constricted distal pale spot, proximal one extended to pale spot at arculus, ends of veins pale at wing margin.

Leg (Fig. 2C ). Brown in colour. Fore femora and tibia dark throughout with proximal small pale region, mid tibia and femora dark throughout; hind femora moderately dark all over and hind tibia with distal pale region; hind tibial comb (Figs 2D , 3E ) with 4 spines, one nearest to spur longest, spur tip frayed.

Abdomen. Brown; two large, subequal, roughly rounded functional spermathecae with sclerotised necks, measuring one 55.20-57.50 (55.35) µm by 46.00-48.30 (47.00) µm, another one 52.90-55.20 (54.05) µm by 41.40-43.70 (42.55) µm; both with slender, moderately long neck, rudimentary third one and faintly sclerotised ring present (Fig. 2E ).

Male (n = 1). Same as female with the usual sexual differences.

Head. Brown. Eyes with interfacetal hair, separated by distance of 2 ommatidia; frontovertex with 28 SCh; palpus pale, palpal segment III moderately swollen with apical shallow sensory pit; PR 2.5.

Thorax. Dark brown.

Wing. Similar with female except morphometric characters. Distribution of macrotrichia in cells; wing length 0.89 mm, width 0.34 mm.

Leg. Brown in colour, all legs uniformly dark without any pale region; hind tibial comb with 4 spines and nearest to spur longest, spur tip frayed.

Abdomen. Ninth sternum with shallow caudomedial excavation; ventral membrane not speculated; ninth tergum with lateral margin more or less straight.

Genitalia (Fig. 2H ). Apicolateral process well developed, moderately elongated, broadly separated caudal margin between them rounded with deep mesal notch; gonocoxite (Fig. 2H ) 80.5 µm long, 52.9 µm wide at base, 27.6 µm wide at apex with ventral root poorly developed while dorsal root well developed. Gonostylus (Fig. 2H ) 62.1 µm long; 18.4 µm wide at base, 4.6 µm wide at apex, slightly curved, narrowed distally. Aedeagus (Fig. 2G ) 62.10 µm long with basal arch low; basal arm short and stout, directed posterolaterad; distal stem stout, tapering distally to blunt, truncated tip; parameres (Fig. 2F ) 52.9 µm long, fused very short distance at base anteriorly, basal arm directed anterolaterad with well developed anterior process, anterolateral arm horn shaped, stem tapering near base, simple, filamentous, pointed distally.

Remarks.

New species shows similarities with C. aequalispinus and C. fuscitibialis but differs from the former in wing pattern and spine structure of hind tibial comb (second nearest the spur longer in C. aequalispinus ). Culicoides fuscitibialis differs from the new species in disposition of some pale spots of wing and structure of third palpal segment. New species shows similarities with C. circumbasalis Tokunaga, 1959 and C. cordiger Macfie, 1934 in wing pattern but differs in many attributes such as eyes with interfacetal hair and pale spots on wing inconspicuous in Culicoides cornatus sp. nov. Culicoides cornatus shows similarities with C. cordiger Macfie, 1934 in wing pattern but differs in attributes like eyes (eyes with interfacetal hair in new species but eyes are bare in C. cordiger ), antennal ratio, mandibular teeth number and distribution of SCo on antennal segments. The new species shows similarities with C. corti Causey, 1938 in some characters like eyes with interfacetal hair, disposition of some pale spots on wing but differs in characters like palpal ratio, distribution of SCo, and on antennal segments (SCo are present on I-XII in C. cornatus but SCo on I and XI-XIII in C. corti ), P/H ratio, shape of the aedeagus and paramere. Distribution of SCo on antennal segments of Culicoides cornatus are similar with C. damnosus Delfinado, 1961 and C. flumineus Macfie, 1937 but differs in characters like eyes with interfacetal hair, antennal ratio, mandibular teeth, and number and disposition of pale spots on wing. Culicoides cornatus shows similarities with C. palawanensis Delfinado, 1961 in SCo distribution and hairy eyes but differs in disposition of pale spots on wing, shape of the parameres and aedeagus, P/H ratio (much less in C. cornatus ), mandibular teeth number (17 in C. cornatus but 11-13 in C. palawanensis ), and antennal ratio. Culicoides cornatus also shares similarities with C. papuensis Tokunaga, 1962 in disposition of some pale spots on wing but differs in the presence of interfacetal hair on eyes in Culicoides cornatus (bare in C. papuensis ), distribution of SCo on the antennal segments, mandibular teeth number, antennal ratio and the shape of parameres. Culicoides cornatus differs with C. hollandiensis Tokunaga, 1959 in pale marking of wing (inconspicuous pale marking in C. cornatus whereas prominent pale marking present in C. hollandiensis ) and shape of the aedeagus (terminally rounded in C. hollandiensis ). Culicoides cornatus differs from C. pampangensis Delfinado, 1961 in structure of paramere and pale marking of wing. Culicoides cornatus is different from C. paragarciai Dyce, 1996 in pale marking on wing (pale marking absent in C. paragarciai ) and structure of hind tibial comb (hind tibial comb with 5 spines and 2nd from the spur is longest in C. paragarciai whereas 4 spines and 1st from the spur longest in C. cornatus ). Culicoides quaterifasciatus Tokunaga, 1959 differs in presence of densely spread macrotrichia on wing and also some pale marking is different from C. cornatus .

Etymology.

The name ' Culicoides cornatus ' refers to Latinised version of cow horn shaped appearance of anterior portion of parameres.

Distribution and bionomics.

The species was collected in adjacent to Indian Sundarbans Deltaic region, a world heritage site (West Bengal state). Adult midges were collected from a cowshed using an ultraviolet light trap in the type locality, situated in the vicinity of Datta River. The type locality is at an altitude of 7.50 m above sea level.

Figures

Figures 2. A-H. Adult male and female of Culicoides cornatus sp. nov. A. Female maxillary palp; B. Female antenna; C. Female legs (femur and tibia); D, Female hind tibial comb; E. Female spermatheca; F. Paramere of male genitalia; G. Aedeagus of male genitalia; H. Male genitalia. Scale bar: 0.05 mm.

Figures 3. A-E. Adult male and female of Culicoides cornatus sp. nov. A. Female wing (Photograph); B. Female thorax (Photograph); C. Female Eye (SEM Photograph); D. Female maxillary palp (SEM Photograph); E. Female hind tibial comb. (SEM Photograph).