Culex (Culiciomyia) macfiei Edwards, 1923

Cornel, Anthony John, Mayi, Marie Paul Audrey, Kowo, Cyril, Foncha, David, Andongma, Esack, Anong, Damian Nota, Elad, Mirabel, Djomo, Charlene, Tchuinkam, Timoleon, Brisco, Katherine K. & Sehgal, Ravinder, 2020, New species of Culex (Culiciomyia) (Diptera: Culicidae) from Talangaye Forest in Cameroon and descriptions and identification keys for males of the Afrotropical species of the subgenus, Zootaxa 4858 (4), pp. 451-506 : 479-481

Culex (Culiciomyia) macfiei Edwards, 1923

Male: This is a small brown to greyish mosquito. The scutal integument is generally brown. Most males collected in the Talangaye Forest have no basal pale markings on the abdominal terga and were identified as Cx. macfiei only once the genitalia were dissected and carefully examined. However, as Edwards (1941) mentioned, all Cx. macfiei males collected in the Talangaye Forest have the pale decumbent scales along the eye margin much reduced relative to those found in other Afrotropical Culiciomyia . Wing 2.30–2.60 mm. Proboscis 1.55–1.77 mm. Forefemur 1.35–1.54 mm.

Head: Row of broad white decumbent scales along eye margin not visible in most specimens, and in those specimens with these scales, the ocular line of scales did not meet in the frontal region of head ( Fig. 20A,C ), small patch of broad decumbent pale scales on sides of head ( Fig. 20A ), narrow decumbent pale scales numerous on vertex ( Fig. 20A,C ), erect scales numerous and uniformly light to dark brown. Maxillary palpus slightly longer than proboscis with palpomeres 4 and 5 bearing setae, palpomere 4 approximately 0.50 (ratio = 0.48–0.54) length of palpomere 5, palpal comb on palpomere 3 as described by Edwards (1941), consisting of 10 or 11 long semi-transparent scales, each ending in a long straight point (acicular or needle-like), similar in shape to those in Cx. cinerellus and Cx. subaequalis ( Fig. 20B ). Antenna and proboscis similar to those of other Culiciomyia .

Thorax: S cutal integument light brown with setae generally appearing light brown to translucent depending on angle of light, setae on anterior promontory and prescutellar area paler, acrostichal setae absent. Thoracic pleura generally not uniform in colour, with prealar area darker brown than upper and lower mesokatepisternum, upper 0.33 of mesanepimeron darker than paler beige to light brown of lower 0.66 of mesokatepisternum ( Fig. 21A ), in some specimens middle 0.25 of mesokatepisternum darker brown than rest of area ( Fig. 21B,C ); pleura devoid of scales except for small patch among setae on upper mesokatepisternum, setae present on following areas: antepronotum, a row of 6 on posterior margin of postpronotum, 3 on proepisternum, prealar knob, a few in middle and posterior margin of mesokatepisternum, and a single lower mesepimeral seta. Capitellum of halter darker than pedicel.

Wing: Scales all dark.

Legs: Coloured similar to those of other Culiciomyia , except for Cx. cambournaci .

Abdomen: Terga light brown with, in some specimens, paler small basolateral spots; sterna light brown to beige.

Genitalia: Each tergum IX lobe with row of 4–6 (mostly 5) setae along upper margin ( Fig. 23C ), typically fewer than in other Culiciomyia species. Genital structures of Cx. macfiei males collected in the Talangaye Forest closely match those described for this species by Edwards (1941). Gonocoxite moderately broad, without distinct ventral lateral setal patch, setae numerous, nearly evenly spaced rows of setae each about 0.67 length of gonocoxite dispersed on ventral and lateral surfaces of gonocoxite ( Fig. 22A ); single prominent subapical lobe with following setae ( Fig. 22A,B ): 3 rod-like setae as in other Culiciomyia , except proximal seta a considerably more dorsally displaced from setae b and c, seta a much darker, striated, broader than b and c, 6 or 7 flattened setae more ventrally positioned and in line with b and c, 1 narrow foliform seta (g) and what is usually a second narrower foliform seta in other Culiciomyia species is replaced by a stout blunt seta (f), seta e absent. Gonostylus bent in middle with single dorsal subapical hook or recurved horn ( Fig. 22A,B ), single subapical seta, a seta below recurved horn (below the crest in other species) and 1 to 3 (mostly 2) setae pre-dorsally positioned in proximity to bend of gonostylus. Aedeagus triangularly broadened basally with distinct tooth at base of each lateral plate ( Fig. 22A , 23A,B ), lateral plate with sharp apex, resembling that of Cx. nebulosus with rounded or sharp apex depending on angle of view, lateral plate with few small rounded denticles on outer edge in dorsal view ( Fig. 23B ), denticles sharper and more numerous than in Cx. nebulosus . Paraproct with typical dense crown of spicules and 3 or 4 small subapical setae, no obvious basal arm.

Additional notes: The male is similar in size to the male of Cx. nebulosus and smaller than the male of Cx. cinereus . The integument of the thoracic pleura of Cx. macfiei is quite variable in colour and we caution using colouration of the scutal and pleural integument to distinguish Culiciomyia , except perhaps Cx. cinerellus , which has two obviously darker stripes on the pleura. Culex macfiei has fewer less obvious pale flat scales along the eye margins than other Culiciomyia . The aedeagus and paraprocts appear very similar to those of Cx. nebulosus . The single hook or recurved horn in place of a crest on the gonostylus is the most distinguishable feature that separates Cx. macfiei from all other Culiciomyia . The most proximal well-displaced broad rod-like seta (a) on the subapical lobe is also an obvious feature that distinguishes the genitalia from the genitalia of other Culiciomyia . The patch of broader stouter setae on the subapical lobe is also quite unique among the Afrotropical Culiciomyia . None of the males collected in the Talangaye Forest have pale basal lateral spots. Some female Culiciomyia collected in the forest have small basal pale spots on the abdominal terga that are often quite subtle to see ( Fig. 24 ). These females could be Cx. macfiei . Edwards (1941) suggested that the basal pale spots can be diagnostic for males and the basal spots may be useful to identify females of this species. However, we caution this as the pale spots in some specimens are very difficult to see and may be absent in some.

Specimens examined: Multiple males were collected in the Talangaye Forest in Cameroon. Specimens CAM 133 c1b 24/I/2017 and CAM 133 c1c 24/I/2017 were reared from an egg raft laid in a bamboo pot. The following specimens were collected in bird-baited net traps or by sweep netting through vegetation on the forest floor: field accession numbers CAM 86 q 13/X/2016, CAM 86 a 1 26/X/2016, CAM 86g 1/XI/2016, CAM 86 f2 2/XI/2016, CAM 86 u2b 7/XI/2016, CAM 86 o 8/XI/2016, CAM 86 x2 8/XI/2016, CAM 86 ya 8/XI/2016, CAM 86 yb 8/XI/2016, CAM 86 yc 8/XI/2016, CAM 86 a 19/XI/2016, CAM 132 i 25/I/2017, CAM 132 r 28/I/2017, CAM 132 b1f 31/I/2017, CAM 132 b 1g 31/I/2017, CAM 132 b1h 31/I/2017, CAM 132 b1i 31/I/2017, CAM 132 b1j 31/I/2017, CAM 132 l 1a 31/I/2017, CAM 132 l1b 31/I/2017, CAM 132 yc 31/I/2017, CAM 132yg 31/I/2017, CAM 132 yj 31/I/2017, CAM 132 a 1a 1/II/2017, CAM 132 l1c 2/II/2017, CAM 132 nb 4/II/2017, CAM 132 kc 5/II/2017, CAM 132 ob 6/II/2017, CAM 132 gd 7/II/2017, CAM 132 ge 7/II/2017, CAM 132 gj 7/II/2017, CAM 163 c 1a 1/V/2017, CAM 163 f 2/ V/2017, CAM 163 sa 2/V/2017, CAM 163 ea 5/V/2017, CAM 163 eb 5/V/2017, CAM 163 fa 5/V/2017, CAM 163 fc

5/V /2017 , CAM 163 lc 10/V /2017 , CAM 202 mb 9/VII/2017, CAM 202 nd 9/VII/2017, CAM 202 nh 9/VII/2017, CAM 202 sa 10/VII/2017, CAM 202 sc 10/VII/2017, CAM 202 u 11/VII/2017, CAM 202 qa 13/VII/2017, CAM 202 qc 13/VII/2017, CAM 202 rb 13/VII/2017, CAM 202 ha 16/VII/2017, CAM 202 hd 16/VII/2017, CAM 202 ta 19/VII/2017 and CAM 202 tb 19/VII/2017.

Figures

FIGURE 20. External features of Culex macfiei. (A,C) dorsal views of the head (vertex); (B) lateral view of the palpal comb scales (100x).

FIGURE 21. Lateral views of the thorax of Culex macfiei.

FIGURE 22. Male genitalia of Culex macfiei. (A) Image (100x); (B) drawn depiction of the subapical region of the gonocoxite and the gonostylus.

FIGURE 23. Male genitalia of Culex macfiei. (A) Image of the phallosome (400x); (B) drawn depiction of the fused lateral plate-aedeagal sclerite of the left and right sides; (C) drawn depiction of tergum IX.

FIGURE 24. Dorsal view of abdominal terga III–V of Culex macfiei.