Anopheles coustani Laveran, 1900

Coetzee, Maureen, 2022, Literature review of the systematics, biology and role in malaria transmission of species in the Afrotropical Anopheles subgenus Anopheles (Diptera: Culicidae), Zootaxa 5133 (2), pp. 182-200 : 185-186

Anopheles coustani Laveran, 1900

1901. Anopheles mauritianus de Grandpre & de Charmoy , synonym

1901. Anopheles paludis var. similis Theobald , synonym

1983. Anopheles coustani sp. A, Coetzee

TYPE LOCALITY: Ankarafantsika , Ampijoroa forest station, Madagascar .

The original description of this species by Laveran (1900) states that the specimens came from an unknown marsh locality on Madagascar. It is not known why Evans (1938) gave the type locality as the island of Reunion, but this error was perpetuated in later works by de Meillon (1947) and Gillies & de Meillon (1968). “ A Synoptic Catalog of the Mosquitoes of the World” ( Stone et al. 1959) gives the correct type locality but later catalogues ( Knight & Stone 1977; White 1980) list it as Reunion. Coetzee (1995) discussed the confusion of the type locality and designated a neotype for An. coustani with the above type locality. The most recent catalogue of Wilkerson et al. (2021) gives the type locality as Madagascar.

DESCRIPTION:

Wing length: Normally 5.0– 5.8 mm, but may be much shorter.

Wing ( Fig. 3a ): Mainly dark, costa with preapical, subcostal and sector pale spots; apical pale fringe spot small, opposite R 2; wing field with variable amount of pale scaling.

Maxillary palpus ( Fig. 3b ): Shaggy, with four pale bands, apex pale.

Legs ( Fig. 3c ): Hindtarsomeres 4 and 5 all pale, apical 0.66 of 3 pale; hindtarsomere 1 with base and apex broadly pale; hindtibia with apical pale spot greatly enlarged ventrally to form a longitudinal white stripe.

Variation: The black band at the base of hindtarsomere 3 may be absent, very narrow or 0.5 as long as the tarsomere. The apical white stripe on the hindtibia may be interrupted distally.

LARVAL HABITAT: The preferred habitats of this species are natural collections of clear water with aquatic and semi-aquatic vegetation, such as swamps, ponds, backwaters of streams, springs, ditches and rice fields.

ADULT BIOLOGY: Adult females can be anthropophilic or zoophilic, mostly feeding outdoors and rarely found resting indoors. Gillies & de Meillon (1968) reported positive salivary gland infections of malarial parasites in An. coustani from Tanzania (0.18%) and the DRC (0.09%) and concluded that it played an insignificant role in malaria transmission. However, more recent research has shown females to be infected with Plasmodium falciparum in the Taveta District of Kenya (0.85–1.78%) ( Mwangangi et al. 2013) and Lake Victoria islands (18.75%) ( Ogola et al. 2017), also Bangui in the Central African Republic (2.3%) ( Ndiath et al. 2016). Both P. falciparum and P. vivax were found in females from Ankazobe (0.01–0.05%) ( Nepomichene et al. 2015) and the Maevatanana District (0.14–0.84%) of Madagascar ( Goupeyou-Youmsi et al. 2020), but only P. vivax was found in southeastern Madagascar (3.2%) ( Finney et al. 2021). Abduselam et al. (2016), however, were unable to experimentally infect Ethiopian An. coustani with P. vivax . DNA of P. falciparum was found by qPCR in six females from northern Zambia ( Ciubotariu et al. 2020). Antonio-Nkondjio et al. (2006) found females infected with P. malariae (3.2%) in Cameroon. Rift Valley Fever virus was isolated from An. coustani in the Haute Matsiatra region of Madagascar ( Ratovonjato et al. 2011), Wesselsbron virus in Kenya ( Villinger et al. 2017) and Zika virus in Kedougou, Senegal ( Diallo et al. 2014). Makanga et al. (2017) in Gabon collected mosquitoes in two wild-life reserves and inferred their host preference through identification of haemosporidian infections in the mosquitoes. Out of 29 An. coustani examined, two were found positive for ungulate parasites.

DISTRIBUTION: Common throughout the Afrotropical Region, from Oman, southwestern Saudi Arabia and Yemen in the north southward to Cape Province in South Africa ( de Meillon 1947; Glick 1992; Irish et al. 2020), and on the associated islands of Madagascar, Mauritius and Reunion ( Grjebine 1966); extending up to altitudes of 2,700 m in Ethiopia and 2,300 m in Tanzania ( Gillies & de Meillon 1968).

Figures

FIGURE 3. Anopheles coustani: a, wing; b, palpomere; c, hindleg (from Gillies & de Meillon 1968).