Aedes (Aedimorphus) durbanensis (Theobald)

Harbach, Ralph E. & Wilkerson, Richard C., 2023, The insupportable validity of mosquito subspecies (Diptera: Culicidae) and their exclusion from culicid classification, Zootaxa 5303 (1), pp. 1-184 : 12-13

Aedes (Aedimorphus) durbanensis (Theobald)

subspecies angolae Ribeiro & Ramos, 1974 —original combination: Aedes durbanensis angolae . Distribution: Angola ( Ribeiro & Ramos 1974).

subspecies durbanensis ( Theobald, 1903a) —original combination: Grabhamia durbanensis . Distribution: Angola, Congo, Democratic Republic of the Congo, Ethiopia, Madagascar, Mozambique, South Africa, Tanzania ( Wilkerson et al. 2021).

The nominotypical subspecies was described from a single female from Durban, South Africa [KwaZulu-Natal Province]. It was characterized as follows (after Theobald 1903a): Head with silvery gray narrow curved scales; clypeus black, with a tubercle on each side near base; proboscis pale brownish yellow overall, apex and base black; maxillary palpus densely scaled, brown basally, white at apex; antenna deep brownish yellow with first 3 flagellomeres dull brick red, first flagellomere with white scales, second and third with dark scales; thorax with rich brown ornamentation, to some extent forming ornamentation at the sides, scutellum with pale narrow curved scales, pleura brown with gray scales; femora and tibiae mottled with pale scales, tarsomeres with narrow pale basal bands; wing mottled with pale and dark scales; abdomen black, with basal white bands and apicolateral yellow spots. Theobald emphasized that “It can be at once told by the thoracic ornamentation, peculiar mottled wings, and basal abdominal banding, and apical yellow lateral spots.”

The male genitalia of the type form were described and illustrated by Edwards (1941), who noted: “Style [gonostylus] with a row of long curved hairs [setae] on distal margin and many more hairs on the surface, spine [gonostylar claw] inserted well before tip at broadest part of style; no apical hair-tuft on coxite [gonocoxite], basal lobe [basal mesal lobe] peculiar in having a regular row of hairs on its margin.” These features were also reported by Ribeiro & Ramos (1974) and Jupp (1996). The pupal stage of durbanensis was very briefly described and the trumpet and paddle illustrated by de Meillon et al. (1945). The egg was described in detail by Linley & Service (1994).

Subspecies angolae was described and illustrated in direct comparison with durbanensis by Ribeiro & Ramos (1974) using female, male and larval specimens of angolae from Moçâmedes, Namibe Province, coastal Angola, 15º 12′ S, 12º 09′ E [verbatim coordinates not verified]. Specimens of durbanensis used in the description were from Natal, South Africa and Lourenço Marques, Mozambique. The authors stated: “In the female sex, Ae. durbanensis angolae subsp. nov. cannot be distinguished from the nominate subspecies.” However, they pointed out diagnostic characters in the male genitalia and larva (see below). Note that Ribeiro & Ramos were motivated to sort out the identity of these taxa, along with a similar species found on the Angolan coast, Ae. natronius Edwards, 1932b: “it became clear not only that the description of the larva, given by Rebelo and Pereira (1) [1943, not seen by us] and taken by Hopkins (2) [1952], was not a satisfactory one but also that a subspecific treatment might be given to the angolan [sic] population of Ae. durbanensis .” For us, the larva of putative durbanensis described and illustrated by Hopkins (1952) is another, yet to be determined, species. It exhibits an incomplete saddle, short anal papillae (as in angolae ), a straight row of comb scales and very short pecten spines.

Males of the two forms differ, according to Ribeiro & Ramos (1974), as follow [figure numbers refer to the original publication]: “Males of both subspecies, however, can be readily separated on the basis of genitalic characters. While Ae. durbanensis angolae subsp. nov. (Fig. 4) has a row of l0–12 setae along the distal margin of basal lobe of coxite [gonocoxite] and has only subequal, small setae on the lateral surface of style [gonostylus], the nominate subspecies (Fig. 1) has only 5 or 6 setae along distal margin of basal lobe of coxite and the 2 or 3 most basal setae of its style are unusually long, about 1/3 or more the length of the style itself.” Other differences are illustrated but we did not undertake further study.

Distinguishing differences of larvae are summarized as follow. In durbanensis: Comb scales asymmetrical, 7 or 8 (6–19) in a single row; siphon longer, index 2.2–2.5 (2.4); pecten spines moderately long and pointed, longest spine 5 or 6 times longer than width at base, mostly asymmetrical with a few basal denticles, distal 2 or 3 spines unequally spaced; anal papillae slightly longer than saddle, with round lanceolate apices. In angolae: Comb scales symmetrical, about 10 (8–20) arranged in 1 or 2 irregular rows; siphon shorter, index 1.7–2.0 (1.9); pecten spines very long, finely drawn out, longest spine about 7 to 10 time longer than width at base, also with a few basal denticles, spines equally spaced on siphon; anal papillae not or only slightly longer than saddle, ovoid or round lanceolate.

Based on the above diagnostic characters, and the great distance between the type localities, without evidence of intermediate forms, we think the two nominal taxa are separate species and here elevate angolae to species status: Aedes (Aedimorphus) angolae Ribeiro & Ramos, 1974 . Aedes angolae is currently listed as a species in the Encyclopedia of Life; however, the authorship is incorrectly attributed to only the first author.

Synonym Grabhamia ocellata Theobald, 1910 was described from four females and three males from Maputo Bay (‘Delagoa Bay’) [ Townsend 1990]. Theobald (1910) listed the collection site as “ Habitat.―Lourenco Marques.” Maputo is the capital of Mozambique, which has the official name of Lourenço Marques. Geographically, the type localities of durbanensis and ocellata are very close. We think the description of the female of ocellata does not differ significantly from that of durbanensis , except for two prominent black spots on the thorax in ocellata , presumably on the scutal fossae. We have not examined the syntype series to verify this. However, for some reason, Theobald did not compare ocellata with durbanensis . Edwards (1911b) stated “The type of G. durbanensis is a small specimen, but evidently the same as G. ocellata .” This implied synonymy has been followed since. However, the lack of comment from Theobald, the distinctive dark eye-like thoracic spots and Theobald’s statement that “The genitalia [of ocellata ] are very marked.”, referring to the large paddle-shaped gonostylus, also seen in later treatments of durbanensis , indicate that a closer look is needed to verify its status. For now, we retain it as a synonym of Ae. (Aed.) durbanensis (Theobald) .