Microculex (Microculex) imitator, Theobald

Bangher, Debora Natalia & Stein, Marina, 2017, Morphological redescription of Culex (Microculex) davisi and Cx. (Mcx.) imitator (Diptera: Culicidae) including structures and stages not previously described, Zootaxa 4347 (1), pp. 56-70 : 57-62

Culex (Microculex) imitator Theobald

Culex imitator Theobald, 1903: 175 (M) Type locality: São Paulo, São Paulo State, Brazil; Kumm, 1933: 564 (M*, F*, L*); Senevet & Abonnenc, 1939: 115 (L*); Rozeboom & Komp, 1950: 155 (M*).

Culex ( Microculex ) argenteoumbrosus Theobald, 1907: 461 (M, F; Microculex ). Type locality: Rio de Janeiro, Guanabara, Brazil (BM).

Culex ( Microculex ) daumasturus Dyar & Knab 1906: 220 (L*). Type locality: La Brea, Trinidad ( USNM).

Culex ( Microculex ) vector Dyar & Knab 1906: 220 (L*). Type locality: Trinidad ( USNM).

Female. Small mosquito, general color brownish. Head: Occiput with decumbent silvery-white scales mixed with dark-brownish scales, erect scales brown, fine and long. Proboscis with dark brown scales, as long as forefemur, length 1.5–1.7 mm (mean 1.5 mm). Maxillary palpus 0.20–0.40 mm (mean 0.20 mm) covered with black scales, second palpomere with some central white scales. Antenna light brown, thin and slightly shorter than proboscis. Thorax: Integument brown, scutum with curved short dark brown scales, mixed with short bronze scales. Scutum with silver scales forming a small spot on mid-anterior portion and followed by non-continuous fringes laterally that extend to prescutellar area. Anterior dorsocentral and acrostichal areas with 2 bare bands flanked by brown scales, followed by 2 lateral white scale-spots surrounded by brown-dark scales. Prescutellar area with dark center portion surrounded by silvery scales ( Fig. 1A ). Scutellar scales whitish. Median lobe of scutellum with 6 long dark brown setae; lateral lobes with 2 or 3 (3) setae. Pleura with integument pale brown, with central brown spot and silver upper mesokatepisternal scales. Remainder of pleural setae golden: 3 or 4 (4) proepisternal, 2 or 3 (3) prealar, 7–10 (8) upper and 1 lower mesepimeral, 4 or 5 (4) upper and 4–6 (6) lower mesokatepisternal setae. Pre- and postspiracular setae absent. Mesopostnotum without scales, integument bright dark brown. Wing: Length 2.1–2.5 mm (mean 2.2 mm) narrow light brown scales on all veins, a characteristic shared by members of the Culex subgenus Culex. Halter: Capitellum with white scales and dark brown scales on apical portion. Legs: Coxae with long, thick and brown setae. Anterior surfaces of femora with white scales, brownish posteriorly. Fore- and midtibia with basal white spot; hindtibia covered completely with dark scales. Fore- and midtarsomeres (I–IV) with some basal white scales; tarsomere V, of the same legs, with dark scales. Hindtarsomeres with a wide basal ring of white scales, sometimes on tarsomere V the white ring covers half of the tarsomere. Ungues dark and simple. Abdomen: Terga with dark scales and small semi-circular basal white spots. Sterna with basal white bands in all segments. Tergum VIII covered with white scales. Abdominal length 1.7–2.0 mm (mean 1.8 mm). Abdominal setae well developed and abundant. Genitalia: Cercus thin and long, postgenital lobe long and wide, slightly shorter than cerci, with 2 small central setae on basal part, apically with 3 setae in lines on each side, the apical more developed. Insula normal, upper and lower vaginal lip weakly sclerotized ( Fig. 2A ).

Male. Smaller than female. Head: Integument brown. Vertex with decumbent curved and thin silver scales, erect scales bright yellow. Maxillary palpus longer than proboscis. Palpomere 1 with dark scales and palpomeres 2–5 with black scales and white basal rings. Palpomeres 3–5 with long black setae. Proboscis slightly shorter than maxillary palpus, with dark brown scales. Antenna strongly verticillate, light brown-scaled, slightly shorter than proboscis. Scutum, abdomen, legs and wing like those of female. Genitalia ( Fig. 2B ): Gonocoxite conical, dorsal surface with numerous setae of different sizes in sclerotized tubercles. Subapical lobe divided. Inner division with 19 or 20 (19) long apical setae. Outer division with 2 long strong setae at apex and 6 short thin setae at base. Gonostylus simple, half as long as gonocoxite, with rounded base and widened in proximal half, with smooth surface, with 2 small setae near apex. Gonostylar claw small, bifurcate. Aedeagus: Lateral plate large with 1 strong retrorse tooth characteristic of the subgenus. Tergum IX: Rounded, with 2 lobes separated by central concavity, with 2 or 3 setae on each in rows. Paraproct crown with 9 digitiform-shaped spicules.

Pupa ( Fig. 3 ). Chaetotaxy as figured; range and modal number of branches in Table 1. Cephalothorax: Integument hyaline with conspicuous spicules, width 1.98–2.39 mm (mean 2.18 mm) length 2.02–2.44 mm (mean 2.23 mm). Trumpet conical, light brown, darker at base, index 5–8.41 (mean 6.7). Tracheal area hyaline, length 0.07–0.12 mm (mean 0.10 mm). Meatus length 0.44–0.52 mm (mean 0.49 mm). Abdomen: Length 2.37–2.54 mm (mean 2.45 mm), width 0.68–0.73 mm (mean 0.70 mm), integument hyaline. Seta 1-I, with more than 80 branches. Paddle ovoid and hyaline, buttress darker. Length 0.57–0.63 mm (mean 0.60 mm), width 0.42–0.48 mm (mean 0.45 mm), index 1.23–1.35 (mean 1.29). Seta 1-Pa with 4 branches, 2-Pa usually single (1,2).

Seta no. CT Abdominal segments Paddle

I II III IV V VI VII VIII

CT = cephalothorax.

Larva (fourth-instar) ( Fig. 4 ). Chaetotaxy as figured; range and modal number of branches in Table 2. Head: Wider than long, width 0.89–1.16 mm (mean 1.0 2 mm), length 0.65–0.81 mm (mean 0.73 mm), integument light brown. Collar dark brown. Dorsomentum with 8 dark teeth on each side of median tooth. Setae 0,1,3,4-C single, smooth; 2-C absent; 5-C with 4–6 (5) branches, 6-C with 1 or 2 (1) branches, 7-C with 6–8 (6) branches, 8-C with 2–4 (2) branches, 9-C with 3–6 (6) branches, 10-C with 1 or 2 (2) branches, 11-C with 5–7 (6) branches, 12-C with 4–6 (4) branches, 13-C with 5 or 6 (5) branches, 14-C single; 15-C with 2 or 3 (3) branches, 6-Mx single. Setae 5– 7-C aciculate, others simple. Antenna: Length 0.43–0.50 mm (mean 0.45 mm), covered with small spicules. Seta 1- A with 4–10 (9) aciculate branches, inserted about 0.67 from base. Setae 2–6-A single. Thorax: Integument hyaline, smooth. Setae 1–3-P and 9–12-M inserted on common tubercles. Prothoracic formula: 1- (1-2) - (4-6) - (1- 2) -1-1-1. Abdomen: Integument hyaline, smooth. Setae 6-I,II double, 7-I with 2 or 3 (2) branches, 7-II with 5–7 (5) branches. Segment VIII: Comb with more than 60 small scales of same size, arranged in 4 rows forming a triangular patch, each with a central apical spicule 4 times longer than lateral spicules. Siphon: Integument light brown, smooth, length 1.64–2.21 mm (mean 1.93 mm), width 0.12–0.20 mm (mean 0.16 mm). Index 11.83. Pecten on basal third of siphon, with 8–10 spines of different sizes. Seta 1-S in 5 pairs, all same size, equal to or shorter than width of siphon at point of insertion, with 3–5 (3) branches. Setae 2,6–9-S single. Segment X: Length 0.32– 0.24 mm (mean 0.28 mm), width 0.15–0.23 mm (mean 0.19 mm). Saddle complete, light brown (similar to siphon), covered with conspicuous spicules. Seta 1-X with 4–9 (5) branches, 2-X single, smooth, 3-X with 1 or 2 (1) branches, 4-X with 7 or 8 (7) branches. Anal papillae 2 times length of segment X, integument hyaline.

Culex Microculex imitator

Figures

FIGURE 1. Dorsal views of scutum of: A, Culex (Mcx.) imitator of the present study. B, Culex (Mcx.) davisi Kumm. C, Culex (Mcx.) imitator Theobald (1903). D, Culex (Mcx.) imitator of Kumm (1933).

FIGURE 2. Genitalia. A, female Culex (Mcx.) imitator. B, male Culex (Mcx.) imitator, 1. detail of the subapical lobe; 2. detail of the tergum IX. C, female Culex (Mcx.) davisi. D: male Culex (Mcx.) davisi, 1. detail of the subapical lobe; 2. detail of the tergum IX. Ce = cercus; GC = gonocoxite; Gs = gonostylus; I = insula; PGL = postgenital lobe; SL = subapical lobe; UVL = upper vaginal lip; IX-Te = tergum IX.

FIGURE 3. Pupa of Culex (Mcx.) imitator. A, cephalothorax. B, metanotum and abdomen. GL = genital lobe; Mtn – metanotum; Pa = paddle; T = trumpet; I – VIII = abdominal segments.

FIGURE 4. Larva of Culex (Mcx.) imitator. A, head. B, thorax and abdominal segments I – VI. C, abdominal segments VII – X. a = antenna; APP = anal papilla; CS = comb scale; Dm = dorsomentum; M = mesothorax; P = prothorax; PS = pecten spine; S = siphon; T = metathorax; I – X = abdominal segments.