Aedes (Aedimorphus) cumminsii (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 : 10-12

Aedes (Aedimorphus) cumminsii (Theobald)

subspecies cumminsii ( Theobald, 1903a) —original combination: Culex cumminsii . Distribution: Angola, Benin, Burkina Faso, Cameroon, Central African Republic, Côte d’Ivoire, Democratic Republic of the Congo, Ethiopia, Ghana, Kenya, Liberia, Mali, Mozambique, Nigeria, Senegal, Sierra Leone, South Africa, South Sudan, Sudan, Uganda, Zambia ( Wilkerson et al. 2021).

subspecies mesostictus Harbach, 2018 —original combination: Aedes (Aedimorphus) mesostictus [nomen novum for mediopunctata Theobald, 1909 ; formerly Aedes cumminsii mediopunctatus ( Theobald, 1909) ; subspecific status by Harbach & Howard, 2007]. Distribution: Ghana, Nigeria ( Wilkerson et al. 2021) .

The taxa under review here are placed in the Aedes (Aedimorphus) dentatus group of Edwards (1941) and McIntosh (1975), which also includes bevisi ( Edwards, 1915), dentatus ( Theobald, 1904) , holocinctus Edwards, 1941, pachyurus Edwards, 1936 and subdentatus Edwards, 1936. According to McIntosh (1975) the dentatus group is “Similar to leesoni group except: scutellar scales always narrow; hind posttarsal claws armed; basal mesal lobe well developed; gonostylus expanding gradually towards apex and therefore without a contrastingly narrow arm; a single strong gonostylar claw present; comb with spines.” We think the similarities in the male genitalia of these species, especially the form of the gonostylus, are evidence of a monophyletic (“natural”) grouping.

The nominotypical form was described from a single female, “perfect except for the ends of the hindlegs”, collected in Bahr-el-Ghazal, Central Africa [north-central South Sudan]. Theobald (1903a) wrote that “It is a large and handsome species, unlike anything I have seen from Africa.” He illustrated the head, a prothoracic lobe and anterior-most part of the scutum. Selected portions of the description follow: “Head deep brown, with narrow-curved, pale golden scales and numerous long, black, upright forked scales, and small, flat, paler scales at the sides; palpi and proboscis deep brown, covered with blackish-brown scales… clypeus deep brown; antennae deep brown, with pale pubescence and deep brown verticillate hairs, basal joint testaceous, with a few pale scales, second joint also testaceous at the base, with a few pale scales on the inside…. Thorax deep rich brown, covered with narrow, hair-like, curved golden scales, with two small patches just in front of the scutellum; scutellum pale brown, with narrow-curved, creamy scales… pleurae brown… with numerous flat creamy-white scales…. Abdomen deep brown, unbanded, with large basal, white, lateral spots… venter paler than the dorsum, with ochraceous hue, with pale creamy scales and the apical borders of the segments dark. Legs deep brown, coxae brown, base and venter of femora pale…. Halteres pallid.”

The synonym of cumminsii , Culicada fuscopalpalis Theobald, 1909 , along with subspecies mesostictus Harbach (as Culicada mediopunctata Theobald, 1909 ) were described from Obuasi [Ashanti Region, Ghana]; fuscopalpalis from a single male and mediopunctata from a single female. In general, both seem similar to cumminsii , but there is no mention by Theobald of resemblance to either. Synonym fuscopalpalis has the “Abdomen deep brown with black scales and basal bands of creamy scales, long golden brown lateral hairs [setae]; venter pale ochreous with narrow black apical bands… a yellow spot at the apex of the hind tibiae…. This well-marked Culicada [sic] can at once be told by the male claspers…. No ♀ was found in the collection.” If it becomes a valid name, since this describes a male, characters of a corresponding female could differ. Subspecies mesostictus (= mediopunctata ) has “a dense bright golden border of scales around the eyes…. Abdomen deep blackish-brown, almost black, the segments, except the basal one, with median basal dull-white patches; border bristles [setae] golden; laterally are pale creamy basal lateral patches; venter yellow scaled, except at the apex, where they are creamy, each segment with a narrow dark scaled apical border… apex of hind tibiae with a prominent white band…. Halteres with pale stem and fuscous knob… easily told by the basal central pale abdominal spots.” Therefore, the abdomen of both cumminsii and mediopunctatus (= mesostictus ) has basolateral pale patches and mediopunctatus (= mesostictus ) also has mesal pale spots.

Also associated with cumminsii sensu lato is a currently recognized synonym of mesostictus , Aedes (Aedimorphus) cumminsi (sic) var. daruensis Evans, 1925 from Moa River, Daru, Sierra Leone. Evans described daruensis by briefly comparing it with cumminsii . She noted: “ Abdomen with small, but well-defined median, basal, pale spots on the third to seventh segments.” Evans provided an illustration of the male genitalia, which are characteristic of other species related to cumminsii .

Edwards (1941) reviewed what was known about this group and included cumminsii and mediopunctatus (= mesostictus ), as a subspecies of cumminsii , in a key. Confusingly, he stated that cumminsii had the “Abdomen all dark above.” and mediopunctatus (= mesostictus ) “Differs from the typical form chiefly if not solely in possessing small median basal whitish spots on the abdominal tergites [terga] in both sexes.”

Adding to the overall confusion concerning the concept of cumminsii sensu stricto, except for the illustration of the head by Theobald (1903a) and various depictions of the male genitalia, none of which show obvious differences, there are no illustrations of any adult characters except for recent color photographs of cumminsii sensu lato from South Africa ( Guarido et al. 2021). Thoracic and abdominal characters in these photographs are sufficient to see resemblances and differences with known descriptions of cumminsii sensu lato.

Hopkins (1952) described and illustrated, in detail, the larva of cumminsii from Uganda but did not associate it with adult characters nor make mention of mediopunctatus (= mesostictus ) or other names associated with cumminsii . The larva he described would be easily recognized since it has the integument of the thorax and abdomen with numerous small, chitinous plates. We have found no characterizations of the pupal stage.

In an ecological study of Aedes species in northeastern South Africa, Guarido et al. (2021), using the COI “barcode” gene ( Hebert et al. 2003), added to the questions surrounding the identity of cumminsii sensu lato. “Species belonging to Aedimorphus subgenera [sic] were recovered in different clusters [in their phylogenetic trees], suggesting that this subgenus is not monophyletic in this study. Sequences produced here from mosquitoes which were identified morphologically as Ae. cumminsii … clustered with Ae. pachyurus (of the same group) and Ae. quasiunivittatus (of another group within the same subgenus) and did not cluster together with sequences from Ae. cumminsii from Kenya …. This species was originally described in Ghana and is widely distributed in Africa. Subspecies based on subtle differences in abdomen scaling have been described, such as ssp. mediopunctatus (Theobald) … and it is not surprising that specimens from South Africa are different. Aedes cumminsii likely represents a complex of species which will require further studies to elucidate their taxonomy”.

The nominal taxa discussed here clearly represent a species complex that will require much more effort to resolve, but there is no indication that mesostictus (= mediopunctatus ) is other than a valid species related to cumminsii . We therefore elevate it to species status: Aedes (Aedimorphus) mesostictus Harbach, 2018 . Aedes mesostictus is currently listed as a species (as Ae. mediopunctatus , incorrectly attributed to Theobald 1905d), in the Encyclopedia of Life.

We do not think there is enough known about this group to place the two junior subjective synonyms ( fuscopalpalis and daruensis) with either Ae. cumminsii or Ae. mesostictus . We therefore choose to list them, for now, as synonyms of cumminsii .