Simulium (Wilhelmia) pseudequinum Séguy, 1921

Crosskey, R. W. & BÁez, M., 2004, A synopsis of present knowledge of the Simuliidae (Diptera) of the Canary Islands, including keys to the larval and pupal stages, Journal of Natural History 38 (16), pp. 2085-2117 : 2105

Simulium (Wilhelmia) pseudequinum Séguy

Material from breeding sites

Gomera: Site G6— 2 pupae, 8 larvae (5 June 1990) ( RWC) . Gran Canaria: Site GC 21— 167 immatures in sample (1 April 1994) ( BM / ANN) . Tenerife: Site T 1— 4 larvae (12 April 1991) ( BM / ANN / MB) . Site T4—3„(z), 3”(z), 32 pupae, 70 larvae (14 June 1990) ( RWC) . Site T6—1„(z), 8 pupae, 46 larvae (24 March 1983) and 1„(z), 7 pupae, 14 larvae (14 June 1990) ( RWC) . Site T7— 35 larvae (9 November 1991) ( BM / ANN / MB) . Site T8—4„(z), 1”(z), 11 pupae, 3 larvae (8 April 1983) ( RWC) . Site T14— 2 larvae (9 April 1983) ( RWC) . Site T18—1”(z) (20 May 1973) ( MB) . Site T19— 30 larvae (5 November 1991) ( BM / ANN / MB) . Site T24— 2 pupae, 12 larvae (15 April 1991) ( BM / ANN / MB) .

Remarks

The enormous range of S. pseudequinum throughout the southern Palaearctic region area has been mapped in Crosskey (1981). The Canary Islands are the westernmost outpost of this distribution, and include the type locality—Tafira in Gran Canaria—not only of this species but also of its synonym, the nominal species S. canariense Séguy. In former times S. pseudequinum was evidently much more abundant in the Canary Islands, especially Gran Canaria, than it is today. At the time of the Crosskey (1988b) paper the occurrence of this species in the Canaries was vouched for almost entirely by the many old pinned adult flies in various collections, especially a long series collected by P. Lesne in 1903 in Gran Canaria which form the type basis for both Séguy’s (1921) nominal species canariense and pseudequinum (see Crosskey, 1981). The first breeding site to be located was found (by MB) near Fasnia in Tenerife (Site T 18), a female being reared from a pupa found in May 1973 in a now long-dry aqueduct; since then eight other breeding places have been found in this island. Elsewhere in the archipelago, breeding places are surprisingly rare, only one having been found in Gomera (G6) and one in Gran Canaria ( GC 21) despite extensive prospections in both these islands.

No chromosomal data are yet available for S. pseudequinum in the Canary Islands. Study of material from Gran Canaria is desirable since this island is the type locality, but should ideally be combined with a study of populations from North Africa (the presumed colonizing source of Canarian populations). Simulium pseudequinum has so far been chromosomally studied only in a population occurring near Tbilisi in Georgia, from where Grinchuk and Chubareva (1972, under the synonym Wilhelmia mediterranea ) have described, and illustrated by photograph and idiogram, the larval polytene chromosomes.