Culex (Melanoconion) dureti Casal & García, 1968

Bangher, Débora N., Almirón, Walter R. & Stein, Marina, 2024, Description of the larva and pupa of Culex (Melanoconion) dureti Casal & Garcia and redescription of the adult male (Diptera: Culicidae), Zootaxa 5443 (2), pp. 253-262 : 254-257

Culex (Melanoconion) dureti Casal & García

Culex (Melanoconion) dureti Casal & García, 1968: 123 (Holotype MG with associates Pe and Le). San Ignacio , Misiones, Argentina (INM).

Culex (Melanoconion) dureti of Heinemann & Belkin 1979: 69, 80 (bionomics); Pecor et al. 1992: 22, 87, 90, 96‒97, 138, 226 (MG, catalog, distribution, holotype info.); Sirivanakarn 1983: 280 (taxonomy); Sugimoto 2009: 30 (collection record); D’Avila 2011: 22 (collection record); Laporta 2012: 107 (collection record); Del Ventura et al. 2013: 170, 172, 181 (collection record); Ribeiro 2014: 65 (collection record); Rossi 2015: (distribution); Torres-Gutierrez & Sallum 2015: 32 (catalog, distribution, holotype info.); Harbach 2024 (taxonomy).

Diagnosis. The male genitalia of Cx. dureti are recognized by the presence of a highly developed foliform seta (seta g) in the distal division of the subapical lobe of the gonocoxite. Furthermore, the lobes of the ninth tergum are underdeveloped, oval-shaped, separated and covered with few setae. The arms of the proximal division of the subapical lobe are proximal. The gonostylus is broad in the apical region, and the aedeagus has a median apical process that ends in four teeth. Fourth-instar larvae of Cx. dureti can be identified by having a siphon index of 6.31‒6.50 (6.40); four pairs of ventral setae 1-S of different sizes, as long to twice as long as the width of the siphon at the point of insertion, and two pairs of smaller dorsolateral setae; and the absence of lateral spicules on the comb scales.

Female. Unknown.

Male ( Fig. 1A, B ). Small, length 2.7 mm. General color light brown. Head: Occiput with broad and white decumbent scales laterally, light golden scales centrally, forked scales dark brown behind. Antenna: Antennal whorls with numerous long light brown setae, length 1.10 mm; pedicel entirely covered with black scales. Proboscis: Length 1.5 mm, covered with dark brown scales. Maxillary palpus: Length 2.00 mm, covered with dark brown scales, last 2 palpomeres with few long setae. Thorax: Antepronotum dark brown. Postpronotum with some minute white scales. Scutal integument light brown, covered with evenly distributed brighter light golden scales, denser on anterior region. All setae of scutum long, thick, dark brown and shiny. Acrostichal setae absent. Dorsocentral setae present, more densely distributed in anterior and middle areas of scutum. Prescutellar area bare. Scutellum covered with silvery white scales, 6 setae on central lobe, 3 on each lateral lobe, all setae long, thick and copper-colored. Pleura with light brown integument, with darker stripes across mesokatepisternum and mesanepimeron; a patch of silver scales on lower margin of mesokatepisternum; golden setae as follows: 2 postpronotal, 2 lower mesokatepisternal, 3 prespiracular; postspiracular setae absent. Wing: Length 2.5 mm. Most veins with narrow elongate uniform light brown scales; broader scales on costa and veins R, R 1, R s, R 2+3, R 2 and R 3. Halter : Scabellum and ventral portion of pedicel covered with light yellow scales; capitellum and dorsal portion of pedicel dark brown. Legs: Entirely covered with dark brown scales, including dorsal side of femora; forefemur length 1.0 mm; hindtibia length 1.5 mm; hindtarsus length 1.5 mm. Ungues of all legs simple and black. Abdomen: Length 1.5 mm; terga covered with black scales except for some white basolateral scales on terga III‒VI; sternum I covered with black scales; sterna II‒VII black-scaled with basal bands of white scales. Genitalia ( Fig. 2A‒D ): Tergum IX bilobed, each lobe mound-like, with high outer angles and covered entirely with short setae, 5 or 6 longer setae on dorsal side. Gonocoxite conical, slender, 2.5 times longer than basal width, covered with numerous setae; subapical lobe divided into proximal and distal divisions, proximal division with 2 slightly divergent straight arms of equal length (setae a and b), distal division not divided, columnar, a long hooked rod inserted on internal angle, a short broad filament projects from basal part; external angle with 2 tubercles, upper tubercle with a long thin filament inserted on a wider base, lower tubercle with a broad foliform seta with a flat apical end and 3 long thin filaments. Gonostylus cylindrical, curved, slightly expanded in middle, with 2 long setae on middle and distal area of expanded middle; apical crest short, wrinkled, extending on ventral surface from fold to apical snout. Lateral plate of the aedeagus slender, T-shaped in the apical region, with an apical tergal process (atp) divided into a posteriorly directed sclerotized tip. The sternal process (asp) features a sclerotized hook at the apex; median process (amp) developed with an irregular tergal-apical edge, ending in 4 distinct apical teeth; basal hook thin, curved, poorly sclerotized. Proctiger crown of paraproct with 11‒13 blade-like teeth; cercus with 2 well-developed setae.

Pupa ( Fig. 2E, F ). Placement and character of setae as figured; range and modal number of setal branches in Table 1 . Cephalothorax: Integument hyaline, smooth, length 2.00‒ 2.25 mm (2.12 mm), width 2.36‒2.38 mm (2.37 mm). Trumpet conical, strongly flared, light brown, darker in tracheoid area, length 5.04‒5.25 mm (5.14 mm), width 0.94‒1.05 mm (0.99 mm), index 5.00‒5.33 (5.16), pinna V-shaped, 0.11‒0.13 mm (0.12 mm) length of trumpet, meatus elongate. Abdomen: Integument hyaline, length 2.31‒2.73 mm (2.52 mm), width 0.65‒0.66 mm (0.65 mm); seta 1-I with 10 main branches, seta 5-IV‒VII shorter than length of following tergum, seta 9-VIII inserted ventrally. Genital lobe: Brown, slightly darker than abdomen; length 0.28-0.30 mm (0.29). Paddle: Ovoid, hyaline, with thickened midrib; length 0.70‒0.73 mm (0.71 mm), width 0.52‒0.60 mm (0.56 mm), paddle index 1.27 (1.21‒1.34); setae 1,2-Pa simple. Genital lobe/paddle index 0.22.

Larva (fourth-instar) ( Fig. 3A–C ). Placement and character of setae as figured; range and modal number of setal branches in Table 2 . Head: Wider than long, length 6.30‒7.30 mm (6.80 mm), width 11.10‒11.70 mm (11.40 mm); integument light brown, without spicules, collar dark brown; dorsomentum triangular with 4 or 5 teeth of different sizes on each side of central tooth; all setae simple, except 7-C aciculate; setae 1,4-C small; setae 2-C absent; seta 5-C short, branched; seta 6-C long, thick. Antenna: Length 5.70‒5.9 mm (5.8 mm), covered with fine spicules; seta 1-A with 17,21 aciculate branches, inserted on distal third of antenna; setae 2‒4-A long, single; setae 5,6-A short, single. Thorax: Integument hyaline with very conspicuous spicules; setae 1‒3-P and 9‒12-P inserted on common tubercles. Abdomen: Integument hyaline, segments I‒III with indistinct spicules; segments IV‒VIII with spicules more evident; setae 6-I,II double; seta 7-I long, single; seta 7-II short with 6 branches. Segment VIII: Comb with 37‒47 long scales of same size, with long apical fringe, in 3 rows forming a triangular patch. Segment X: Length 3.40‒3.50 mm (3.45 mm), width 2.20‒2.30 mm (2.25 mm); saddle complete, with minute apical spicules; seta 1-X with 4 branches; seta 2-X with 3 small secondary branches; seta 3-X long, single; seta 4-X (ventral brush) with 4,6 pairs of aciculate setae, each with 4‒6 branches. Anal papillae hyaline, 1.5‒2.0 times as long as segment X. Siphon: Light brown, surface smooth, length 11.70‒12.00 mm (11.85 mm), width 1.80‒1.90 mm (1.85 mm), siphon index 6.31‒6.50 (6.40); pecten on basal third with 17‒22 spines of different sizes; 4 pairs of ventral setae 1-S of different sizes, length 1‒2 times width of siphon at point of insertion, with 4‒6 branches, also with 2 small dorsal double setae; setae 2,6‒9-S single; seta 2-S with small secondary tooth on basal portion; siphon/saddle index 3.43.

Material examined. 3M, 3 MG, 3 Pe, 2 Le as follows. Holotype : M, MG, Pe, Le. Argentina, Misiones , San Ignacio. 26-IV-1967 (Bejarano, Duret, Mauri, Casal and García coll.), with larval and pupal exuviae mounted in balsam (Ga 353-10) ( Fig. 1 ). Paratypes : 2M, 2 MG, 2Pe, 1Le (Ga 353-15) (Ga 353-104).All specimens are deposited in the Administración Nacional de Laboratorios e Institutos de Salud ( ANLIS, collection number: Ent 10027) .

Bionomics. The immature stages (their exuviae) used for describing the species were collected from the edges of a small lake with clear permanent water and abundant herbaceous vegetation exposed to direct sunlight ( Casal & Garcia 1968; Heinemann & Belkin 1979).

Distribution. Culex dureti is currently recorded from Argentina, Brazil, Paraguay and Venezuela ( Torres-Gutierrez & Sallum 2015). In Argentina, it has been found in Misiones Province ( Casal & Garcia 1968; Rossi 2015).

Figures

FIGURE 1. A) General view of the male of Culex (Melanoconion) dureti. B) Details of the scales of the occiput.

FIGURE 2. A‒D, Genitalia of Culex (Melanoconion) dureti: A) gonocoxite and gonostylus; B) tergum IX; C) aedeagus; D) paraproct. E,F, Pupa of Culex (Melanoconion) dureti: E) cephalothorax; F) metanotum and abdomen. a, seta a; AeS, aedeagal sclerite; amp, apical median process; asp, apical sternal process; atp, apical tergal process; b, seta b; bh, basal hook; CSe, cercal setae; CT, cephalothorax; dSL, distal division of subapical lobe; f, seta f; g, foliform seta g; Gc, gonocoxite; GL, genital lobe; Gs, gonostylus; h, hooked seta h; l, seta l; LP, lateral plate; Mtn, metanotum; Pa, paddle; Ppr, paraproct; Pr, proctiger; pSL, proximal division of subapical lobe; s, seta s of dSL; SL, subapical lobe; T, trumpet; I–VIII, abdominal segments; IX-Te, tergum IX; 1–14, setal numbers. Scales in mm.

FIGURE 3. Fourth-instar larva of Culex (Melanoconion) dureti: A) head; B) thorax and abdominal segments I–VI; C) abdominal segments VII, VIII, X and siphon. A, antenna; APP, anal papillae; C, cranium; CS, comb scale; Dm, dorsomentum; M, mesothorax; P, prothorax; PS, pecten spine; S, siphon; T, metathorax; I–X, abdominal segments; 1–14, setal numbers. Scales in mm.