Simulium (Simulium) intermedium Roubaud, 1906

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 : 2106

Simulium (Simulium) intermedium Roubaud

Material from breeding sites

Gomera: Site G2—1„(z) (12 April 1974) ( MB) and 3„(z), 1”(z), 32 pupae, 115 larvae (6 June 1990) ( RWC) . Site G4—1„(z) (6–7 June 1990) ( RWC) . Site G5—1„(z), 1”(z), 23 pupae, 37 larvae (6 June 1990) ( RWC) . Site G6— 2 pupae, 12 larvae (5 June 1990) ( RWC) . Site G7— 2 pupae, 3 larvae (5 June 1990) ( RWC) . Site G8—2„(1z) (29 March 1978) ( MB) . Gran Canaria: Site GC3—larvae present (29 March 1994) ( BM / ANN) . Site GC4— 95 immatures in sample (29 March 1994) ( BM / ANN) . Site GC5— 1 larva (24 April 1996) ( RWC) . Site GC6— 1 immature in sample (28 March 1994) ( BM / ANN) , 3„(z), 3”(z), 47 pupae, 67 larvae (24 April 1996) ( RWC) . Site GC7—larvae present (29 March 1994) ( BM / ANN) . Site GC8— larvae present (28 March 1994) ( BM / ANN) . Site GC9— 4 pupae, 21 larvae (30 March 1995) ( RWC) , 3 pupae, 14 larvae (1 April 1995) ( RWC) , 128 immatures in sample (19 November 1995) ( BM / ANN) , 5 pupae, 22 larvae (21 April 1996) ( RWC) and 2„(z), 3 pupae, 6 larvae (20 March 1997) ( RWC). Site GC10— 172 immatures in sample (29 March 1994) ( BM / ANN). Site GC12—larvae present (28 March 1994) ( BM / ANN). Site GC13—1„(z) (31 December 1987) ( MB) and 3 immatures in sample (28 March 1994) ( BM / ANN) . Site GC17— 810 immatures in sample (30 March 1994) ( BM / ANN) . Site GC18—larvae present (30 March 1994) ( BM / ANN) . Site GC19—larvae present (31 March 1994) ( BM / ANN) . Site GC20— 62 immatures in sample (31 March 1994) ( BM / ANN) . Site GC21— 153 immatures in sample (1 April 1994) ( BM / ANN) . La Palma: Site LP1— 3 larvae (17 April 1981) ( RWC) . Site LP2—3„(z), 1”(z), 37 pupae, 126 larvae (16 April 1981) ( RWC) .

Tenerife: Site T1— 1 pupa, 1 larva (12 April 1991) ( BM / ANN / MB) . Site T12— 11 pupae, 79 larvae (10 June 1990) ( RWC) and 2 larvae (10 November 1991) ( BM / ANN / MB) . Site T14—2„(1z) (24 March 1983) ( MB), 11 larvae (9 April 1983) ( RWC) . Site T15— 17 larvae (22 December 1970) ( HD) .

Remarks

This species is widespread in much of Europe and North Africa, occurring also in the Balearic Islands and Madeira. The previous report (Crosskey, 1988b) recorded breeding sites in Gomera, La Palma and Tenerife, but not Gran Canaria, from which only wild-caught adult flies were at that time known; since then, S. intermedium immatures have been collected at 15 of the 21 simuliid breeding sites located in Gran Canaria—where it can be regarded as the commonest species present. The female holotype of S. intermedium , from Güimar in Tenerife, has been discussed by Crosskey (1965); it possesses the shining black (instead of dull grey pollinose) frons that is the diagnostic character separating the female of S. intermedium from that of other members of the Simulium ornatum group.

Several fixed larvae collected (RWC) on 18 April 1981 from the Los Tilos aqueduct in La Palma were sent to the late K. H. Rothfels at that time for cytological analysis but failed to make usable preparations. However, the chromosomes of larvae from two samples collected (RWC) in 1995 in the Barranco de la Mina (Gran Canaria) have now been briefly reported upon in a comparison between the chromosomes of S. intermedium larvae in northern Sweden and the Canary Islands (Adler et al., 1998: 374). Chromosomes in the Swedish population differed from the Gran Canaria population by lacking two fixed inversions on chromosome IIL. The significance of this is uncertain because of the paucity of data from elsewhere, only Post (1979, as nitidifrons) in Britain having researched the chromosomes in detail. Ideally any future investigation should include material from Tenerife, as this island is the type locality, and could show differences in the polytene chromosomes from populations in Gomera and Gran Canaria.