Anopheles (Cellia) wellcomei 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 : 80-82

Anopheles (Cellia) wellcomei Theobald

subspecies ugandae Evans, 1934 —original combination: Anopheles distinctus var. ugandae (subspecific status by Gillies & de Meillon 1968). Distribution: Angola, Botswana, Burundi, Democratic Republic of the Congo, Gabon, Gambia, Kenya, Senegal, Tanzania, Uganda ( Ribeiro & Ramos 1975; Gillies & Coetzee 1987; Wilkerson et al. 2021).

subspecies ungujae White, 1975 —original combination: Anopheles (Cellia) wellcomei ungujae . Distribution: Island of Zanzibar, Tanzania ( White 1975).

subspecies wellcomei Theobald, 1904 —original combination: Anopheles wellcomei . Distribution: Angola, Benin, Botswana, Burkina Faso, Cameroon, Central African Republic, Chad, Côte d’Ivoire, Democratic Republic of the Congo, Eritrea, Ethiopia, Gabon, Gambia, Ghana, Guinea, Kenya, Mali, Mauritania, Mozambique, Niger, Nigeria, Senegal, Seychelles, South Sudan, Sudan, Tanzania, Togo, Uganda, Zambia, Zimbabwe ( Wilkerson et al. 2021).

The nominal taxa treated here are members of the Wellcomei Group ( Gillies & de Meillon 1968) of the Myzomyia Series ( Christophers 1924), which also includes An. distinctus ( Newstead & Carter, 1911) , An. erepens Gillies, 1958 and An. theileri Edwards, 1912c . Species in the Wellcomei Group lack aedeagal leaflets (except theileri ) and have adaptations in the immature stages for climbing out of the water ( Evans 1934). The larvae have large dense hair-like spicules on the thorax and abdomen, and pupae have a row of ventrally directed hooks on the cephalothorax and the paddle is fringed externally with coarse spines. Verification of these characters for subspecies ungujae is still needed, because it is known only from a single female.

The original description of An. wellcomei (adult female) includes an informative color illustration. Theobald’s (1904) diagnosis follows: “Head black with dense white, yellow and brown upright forked scales, the white ones in front and two long hair-like projecting white tufts; palpi yellow, black at the base with two white bands on the yellow area. Thorax ashy, chestnut-brown at the sides and with hair-like golden scales; abdomen brown, unbanded with brownish golden hairs. Wings mostly yellow scaled, costa jet black with two yellow spots and three or four black spots on the wing field.” Also of note are other characters from the original description and subsequent observations. The maxillary palpus is black basally and ochreous (yellow orange to orange) on approximately the distal two-thirds, with two broad white bands and a third narrow band apically. The proboscis is dark on the proximal half, and the distal half is ochreous like the palpus. The wing is distinctive and was later described by Evans (1927): “To the naked eye the wings seem yellow with a narrow, black anterior border.” Also from the original description: Costal wing spots, on costa and vein R 1, include subcostal, preapical and apical pale spots. There is also a small sector pale spot on R 1, which is almost entirely pale proximally. Wing mostly pale yellowish with small dark spots (noted by Theobald to vary) on veins R 2, R 3, R 4+5, M 1, M 2 and 1A. Fringe scales pale at ends of all veins, wing apex and entire border of the anal cell. “Legs brown with very narrow apical yellow bands.” Legs subsequently described by Gillies & de Meillon (1968) as: “Tarsus 1–3 of fore legs [foretarsomeres 1–3] with distinct but narrow apical pale bands; mid legs similar but pale bands less distinct; hind legs with tarsus 1–4 [hindtarsomeres 1–4] distinctly banded apically.”

Anopheles wellcomei was described from three females from Baro and Pibor, Sudan (now in South Sudan). “Dr. Balfour states that ‘it boarded the steamer in the evening at Baro and bit freely.’” Also, “It is abundant on the Baro [River].” Townsend (1990) recorded the label data for the three syntypes as “ wellcomei Theobald, 1904 c: 64–66 (Anopheles) . Syntypes (3) ‒ Sudan: 1 female, [Eastern Equatoria], Baro [5 o 45′N 31°42′E]; 2 females, [Sobat], Pibor.” David Pecor (pers. comm.) interprets the Baro and Pibor collection localities to be place names with coordinates of 5.75, 31.7 and 6.79853, 33.13045, respectively (see: https://arcg.is/0D4nD).

Two other nominal species were included with the above species by Evans (1934) in the “ distinctus series” ( Anopheles walravensi Edwards, 1930 and Anopheles schwetzi Evans, 1934 ). They “share a peculiarity in wing markings, namely, the reduction or loss of some of the pale costal spots, especially of the sector and subcostal, at least the basal 2/3 of the costa being entirely dark...”. The relative vagueness of the lack of pale spots on the costa and few dark spots on the rest of the wing (along with similarity in leg coloration) presumably led taxonomists to include similar-looking species in the concept of the “ distinctus series”. Also vague to us is the ill-defined designation of varieties and subspecies throughout the taxonomic history of this group of species. To illustrate, it is perhaps informative to look at name combinations over time.

Pyretophorus distinctus Newstead & Carter, 1911 : To genus Anopheles by Evans (1927).

Pyretophorus distinctus var. melanocosta Newstead & Carter, 1911 : To synonym of An. distinctus by Evans (1934).

Anopheles theileri Edwards, 1912c : New name for Pyretophorus albipes Theobald, 1911a .

Anopheles theileri var. brohieri Edwards, 1929b : To species rank, An. brohieri , by Gillies & de Meillon (1968).

Anopheles distinctus var. ugandae Evans, 1934 : To An. wellcomei subspecies ugandae by Gillies & de Meillon (1968) (elevated to species herein).

Anopheles walravensi Edwards, 1930 : No change.

Anopheles schwetzi Evans, 1934 : No change.

Anopheles theileri var. septentrionalis Evans, 1934 : To synonym of An. brohieri Edwards, 1929b by Gillies & de Meillon (1968).

Anopheles walravensi var. milesi de Meillon & Evans, 1935 : To synonym of An. wellcomei subspecies ugandae by Gillies & de Meillon (1968).

Anopheles michaeli de Meillon & Leeson, 1940 : To synonym of An. schwetzi by Gillies & de Meillon (1968).

Anopheles wellcomei subspecies erepens Gillies, 1958 : To species rank, An. erepens , by Gillies & Coetzee (1987).

Anopheles wellcomei subspecies ungujae White, 1975 (elevated to species herein).

Subspecies ugandae was described from Kampala, Uganda. The two type localities of wellcomei, Baro and Pibor , are 606 km and 716 km, respectively, north of Kampala. Larvae, pupae and adult females were available to Evans (1934), and were illustrated in part. A holotype female with associated larval and pupal exuviae is in the Natural History Museum, London. Evans (1934) did not clearly distinguish ugandae from other taxa in the “ distinctus series” but instead alluded to differences between it and “pale forms of distinctus ”, “the type of the former var. melanocosta ”, pupal paddle “Shape more nearly ovoid than usual, but apparently less so than in theileri and the type form of distinctus ”, “Larvae and pelts [exuviae] resembled those of the type form and of A. theileri ”, “Outer clypeals, as in type form and some specimens of theileri , very short and bluntly pointed distally” and, in addition, there were vague comparisons to the antennae and abdominal setae of theileri . The distinguishing character, however, provided in a key to adult females, is “Outer half of proboscis with creamy or whitish scales; palpi with dark brown scales confined to the basal one-third” in wellcomei , and “Outer half of proboscis dark-scaled; palpi with dark-scaled areas on outer two-thirds” in walravensi , distinctus var. ugandae , distinctus “type form” and schwetzi . These same characters were used by Gillies & Coetzee (1987) to distinguish wellcomei wellcomei from wellcomei ugandae . Gillies & Coetzee were not able to separate the larvae or pupae of species in the Wellcomei Group (as the wellcomei section).

Gillies & de Meillon (1968) mapped the distributions of subspecies wellcomei and ugandae (their fig. 47). Subspecies wellcomei is shown across central sub-Saharan Africa and subspecies ugandae is distributed more in southeastern Africa, but with a large overlap of the two in Uganda, Republic of Congo, Tanzania, Kenya and southern South Sudan. Gillies & Coetzee (1987) stated that “ Gillies and De Meillon (1968) recognised the 3 subspecies, w. wellcomei , w. ugandae and w. erepens . The last named was a very dark form from an isolated area in Tanzania and Kenya. The pale form with flavescent palps and proboscis ( wellcomei ) is typical of the northern savanna while, from Uganda southwards, forms lacking this overlay of pale scales predominate ( ugandae ). However, material collected more recently from the western limits of the northern savanna in Senegal (Dr M Cornet) and from adjacent parts of The Gambia lacks the flavescent scales and has a rather darker wing, both characters diagnostic of subsp. ugandae . This pattern of variation, in which there is a tendency for certain peripheral as well as southern populations to become darker, means that ugandae is a rather less satisfactory taxon than appeared when Gillies and De Meillon redefined it. However, the name ugandae must be applied to Sene-gambian specimens even though this invalidates to a certain extent the picture of distribution previously presented.” This uncertainty suggests to us that the variability could indicate a species complex.

Given the diagnostic character of the pale coloration of the apical half of the maxillary palpus and proboscis in subspecies wellcomei , which are dark in subspecies ugandae , the relative closeness of type localities and the extensive overlapping distributions, we believe these are genetically distinct taxa. Therefore, we hereby elevate subspecies ugandae to specific status: Anopheles (Cellia) ugandae Evans, 1934 . Anopheles ugandae is currently listed as a species in the Encyclopedia of Life. As indicated above, we agree with Gillies & de Meillon (1968) that An. walravensi var. milesi de Meillon & Evans, 1935 (type locality: Victorian Falls, Zimbabwe) is probably a synonym of An. ungandae (type locality: King’s Lake Area, Kampala, Uganda). However, the possibility that further study could reveal that milesi is a separate species cannot be ruled out.

White (1975) named and designated a holotype for An. wellcomei subspecies ungujae based on a brief description by Gillies (1958) of a single female from Zanzibar, which Gillies called both Anopheles wellcomei subsp. indet . and A. wellcomei , Zanzibar form. Gillies noted that “The finding of A. wellcomei on the island of Zanzibar extends the known range of the species right across Africa. It is interesting to note that moderately intensive collecting on the adjacent East African coast has failed to reveal this species, although erepens is abundant in the arid regions 100 or so miles inland.” White (1975) stated that “Apart from its discreet distribution, this subspecies is readily separable from other forms of wellcomei by extension of the pale sector wing-spot onto the costa and by the almost completely pale first wing vein (vide Figure 4 in Gillies, 1948:10; Plate 82b in Gillies & De Meillon, 1968:177).” However, a complete description of the holotype is needed. Based on the stated discrete characters and distribution we believe, pending further morphological and molecular study, that subspecies ungujae should be afforded species status: Anopheles (Cellia) ungujae White, 1975 . Anopheles ungujae is currently listed as a species in the Encyclopedia of Life. Without a complete description of the holotype and collection and study of the adult male and immature stages, its placement in the Wellcomei Group remains uncertain.