Culex (Maillotia) salisburiensis 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 : 100-101

Culex (Maillotia) salisburiensis Theobald

subspecies capensis de Meillon, 1935 —original combination: Culex (Neoculex) salisburiensis var. capensis (subspecific status by White 1975). Distribution: South Africa (de Meillon 1935).

subspecies coursi Doucet, 1949 —original combination: Culex coursi (subspecific status by White 1975). Distribution: Madagascar ( Doucet 1949).

subspecies salisburiensis Theobald, 1901b 1901c —original combination: Culex salisburiensis . Distribution: Democratic Republic of the Congo, Kenya, Lesotho, Madagascar, Nigeria, Saudi Arabia, South Africa, South Sudan [but not Sudan ( Simsaa et al. 2021)], Uganda, Yemen, Zambia, Zimbabwe ( Wilkerson et al. 2021).

This is another of the many Afrotropical species of Culex that have been poorly collected, little studied and are imperfectly known taxonomically. Many nominal species placed in the genus have been reduced to subspecies or synonyms when they were not studied as part of revisionary works. This applies to White (1975), who recognized variety capensis de Meillon, 1935 and the species coursi Doucet, 1949 as subspecies of salisburiensis . The concept of capensis is clouded by the loss of the type material, the original description based only on the adult female and its synonymy with salisburiensis by Edwards (1941). The issue is further complicated by the description of Cx. salisburiensis naudeanus Muspratt, 1961 from Cape Province of South Africa, which includes the type locality of capensis . As surmized by White (1975), Muspratt “dismissed the availability of the name capensis because of the lack of type-material. He might also have wanted to allow for it being a species distinct from salisburiensis , since its identity cannot be completely resolved until further topotypic material is obtained. However, the published description of capensis quite supports its inclusion as a form [subspecies] of salisburiensis .” But how the description supports Mattingly’s conclusion is questionable as it only states that capensis is similar to salisburiensis but is darker and the proboscis is slightly longer than the forefemur. It is interesting to note that de Meillon (1935) questioned the recognition of capensis as a mere variety of salisburiensis : “Unfortunately, we did not collect any males, so for the present we have given this insect varietal rank only.” Unlike capensis, Muspratt described naudeanus from a series of males and females with associated larval and pupal exuviae and fourth-instar larvae, and found that “This form appears to differ chiefly from C. salisburiensis *) in the larval comb and pecten spines… which are quite distinct.”—the asterisk and parenthesis refer to a footnote that says “The variety capensis De Meill. could not be compared owing to lack of type specimens.” As for the male genitalia, Muspratt stated that “no differences [were] found from [the] salisburiensis typical form.”

Knight (1953) identified a male and two females with associated larval and pupal exuviae collected in Yemen as specimens of Cx. salisburiensis , but questioned the identification because of many differences noted between the Yemen adults and the description of salisburiensis provided by Edwards (1941). To confirm the identification, Knight sent a full description of the specimens and a drawing of the male genitalia (fig. 2 in Knight 1953) to Peter Mattingly for comparison with specimens of salisburiensis deposited in the museum in London known at the time as the British Museum (Natural History). Comparisons were made with specimens from [South] Sudan, Kenya, Zambia (as N. Rhodesia), Zimbabwe (as S. Rhodesia) and many locations in South Africa, including Cape Province. Mattingly responded with the following assessment.

I am afraid almost all of the differences you noted are due to errors in Edwards’ description. The only difference of any significance is that, while the Nairobi males have terminalia [genitalia] identical with the Yemen form, those from further south lack the longest of three accessory bristles [seta f] on the subapical lobe and one of the two small setae on the dististyle [gonostylus]. It is clear therefore that we have a northern and a southern form but it is impossible to say which is the type form since I have no males from Salisbury [Harare, Zimbabwe]…. It may be possible eventually to distinguish two subspecies. The southern forms are certainly much darker than yours, especially with respect to the scutal scaling but the Nairobi specimens are intermediate and, I should think, would probably intergrade in Eritrea. Also the two specimens from Chilanga [ Zambia] suggest that there is considerable seasonal variation since one, collected in January, is very dark, while the other collected in November, is as pale as the Nairobi form. Edwards’ figure for the length of the female palps [maxillary palpi] seems to have been based on a single aberrant or shrunken specimen; and the tergal bands are variable, even in the same locality. The other differences are just errors in description.

As confirmation of the errors in Edwards’s description, we note that seta g of the subapical lobe of the gonocoxite illustrated by Knight as having “a distinctive angular and serrate margin and with a distinctive median pigmented area” bears no resemblance to the simple leaf illustrated by Edwards (fig. 83a).

Although White (1975) synonymized naudeanus with capensis , this was apparently unknown to or ignored by Jupp (1996), who treated naudeanus as a subspecies of salisburiensis . He distinguished the larva of naudeanus from the larva of the typical form in a key and an illustration of the terminal abdominal segments, and illustrated the gonocoxite and phallosome of the male genitalia. His study was based on specimens collected in southern Africa that were housed in the former National Institute for Virology and the South African Institute for Medical Research, which were united in the year 2000 to form the South Africa National Institute for Communicable Diseases. The two forms in southern Africa are clearly easily distinguished by the form of the comb scales and pecten spines, as originally noted by Muspratt (1961). Subspecies naudeanus differs from the typical form in having mostly spine-like comb scales with saw tooth-like lateral margins and simple curved darkly pigmented pecten spines. In the typical form, the comb scales are evenly fringed and the pecten spines have a row of proximal denticles. It should also be noted that head seta 5-C is about as long and thick as seta 6-C in larvae of naudeanus, as opposed to being about half as long and thinner in the type form (Muspratt 1961). A comparison of the drawings of the gonocoxite provided by Knight (1953) and Jupp (1996) indicates that setal group d–f of naudeanus (= capensis ) consists of fewer setae and seta g has a more globose head and a narrower stem. One can only imagine how many other differences would be found to distinguish capensis from the typical form if the adults, larvae and pupae were subjected to a comprehensive comparative anatomical study. Based on the distinctive differences in structures of the larvae and male genitalia, and also because capensis and the type form occur in the same geographical areas, we believe that further study will reveal that the former is a genetically separate species; thus, we believe that capensis should be formally afforded species status: Culex (Maillotia) capensis de Meillon, 1935 . Culex capensis needs to be added to the list of Culex species recognized in the Encyclopedia of Life.

Subspecies coursi was described as a full species based on larvae collected at the edge of a rice field on the road between Bejofo and Amparafaravola in the Alaotra-Mangoro Region of Madagascar ( Doucet 1949). The adults are unknown. White (1975) dismissed the specific status of coursi based on his perception that “the published description differs insufficiently from that of [the] salisburiensis type-form to warrant maintaining coursi above subspecific rank.” We have carefully examined the description (in French, translated into English by Hopkins 1952) and illustrations of coursi provided by Doucet and it seems obvious that White completely misjudged the degree of morphological distinction from salisburiensis . The larva of coursi bears the following exceptional differences from the larva of salisburiensis: Dorsomentum differently shaped, resembling an equilateral triangle with six acute lateral teeth (more convex with four or five larger blunter lateral teeth in salisburiensis ); comb comprised of about 35 rather broad scales with a fringe of rather coarse spicules (about 40–50 narrower scales with an even fringe of slender spicules in salisburiensis ); siphon relatively short, broad at the base and tapered to the apex, index about 5 (siphon longer, more or less cylindrical, index about 7 in salisburiensis ); three pairs of seta 1-S, each seta with 2–4 branches and distinctly shorter than the diameter of the siphon (four to six pairs of seta 1-S, each seta with 5–8 branches and distinctly longer that the diameter of the siphon in salisburiensis ); siphon with two anterolateral setae, each with 2 or 3 branches (siphon with three anterolateral setae, each with 1 or 2 branches in salisburiensis ); anal papillae about as long as the saddle, dorsal pair about the same length as the ventral pair (anal papillae shorter than the saddle, dorsal pair distinctly shorter than the ventral pair in salisburiensis ). Based on these striking differences, we agree with Doucet (1949) and Hopkins (1952) that coursi is unlikely to be conspecific with salisburiensis , which it does not resemble as closely as was perceived by White (1975). Additionally, coursi is apparently sympatric with salisburiensis in the Lake Alaotra region on the eastern slopes of the central highlands of Madagascar ( Doucet 1949; Tantely et al. 2016). Obviously, it is necessary for coursi to be reinstated to its original status as a distinct species: Culex (Maillotia) coursi Doucet (1949) . Culex coursi is currently listed as a species in the Encyclopedia of Life.

Two nominal species are recognized as junior synonyms of Cx. salisburiensis : Cx. bostocki Theobald, 1905c (type locality: Transvaal Province, South Africa) and Cx. salisburiensis var. amboannulatus Theobald, 1913a (type locality: Hout Bay, Pinelands and Palmiet River, Cape Province, South Africa). These nominal forms are based on descriptions of adult specimens—the type specimen of bostocki is a female and the type of amboannulatus is a male (genitalia not described or illustrated). In the absence of information about the larvae and male genitalia, it is not possible to know whether the two nominal forms might be conspecific with Cx. capensis rather than Cx. salisburiensis ; consequently, for the time being they should remain as synonyms of the latter species.