Simulium (Eusimulium) petricolum (Rivosecchi)

Crosskey, Roger W. & Crosskey, Margaret E., 2000, An investigation of the black ¯ y fauna of Andalusia, southern Spain (Diptera: Simuliidae), Journal of Natural History 34 (6), pp. 895-951 : 915-916

7. Simulium (Eusimulium) petricolum (Rivosecchi)

Spain references: Grenier and Bertrand (1954, as aureum , in part), Beaucournu-Saguez (1975b,

as latizonum), GonzaÂlez PenÄa (1985, as latizonum), GonzaÂlez PenÄa (1990), VincËon and

Clergue-Gazeau (1993), GonzaÂlez (1997).

Andalusia records

Authors’ material. Site 19: 46 larvae. Site 25: 1m (1), 4 pupae (pharate adults). Site 50: 1 (l1), 3 pupae. Site 56: 1 (l 1), 7 pupae, 2 larvae. Site 119: 2 pupae, 18 larvae (18.v.1986).

Previous reports. AlmerõÂa: Sierra de Filabres, Calar Alto [WG42], JaeÂn: Sierra de Almaden, RõÂo Fuenmayor, S of Torres [VG57] (ref. VincËon and Clergue-Gazeau, 1993).

The following records of `S. aureum ’ or `S. aureum s.l. ’ probably relate to petricolum , namely Granada: channel 3 km before Gujar Sierra [VG51] and Sierra Nevada, Picacho de Veleta [VG60] (ref. Beaucournu-Saguez, 1975a);`rio du village de Laroles’, [VF99] (ref. Grenier and Bertrand, 1954). [We have ourselves found petricolum at Cherin (Site 56) in RõÂo Laroles downstream from the Grenier and Bertrand site.]

Remarks

The early stages are very localized. They occur in stony mountain watercourses and are much less widely distributed than those of S. velutinum , from which they cannot be reliably distinguished morphologicallyÐalthough larvae of petricolum are typically darker than those of velutinum and often appear rather black to the naked eye. Our identi®cations are based on reared and/or pharate adults, except for the larvae from Site 19 which (from the habitat) we are con®dent belong to this species even though we did not have pharate adult characters available for con®rmation. Distinguishing characters from S. velutinum lie in the spermatheca, the male genitalia and the male hind basitarsus. The spermatheca has the sclerotized nipple-like extension of the capsule at the base of the spermathecal duct that is typical for the aureum species-group (®gure 6, arrowed); in the female of S. velutinum the nipple-like capsule extension is absent (®gure 9, arrowed) and the junction of spermatheca and spermathecal duct appears as a clear disc (®gure 12). In males of S. petricolum the blade of the ventral plate is very narrow (®gure 4) and the apico-external margin of the gonostyles is produced to a point (®gure 5, arrowed), whereas in males of S. velutinum the blade of the ventral plate is distinctly triangular (®gure 10) and the apico-external margin of the gonostyles is rounded (®gure 11, arrowed); the male hind basitarsus is broadly fusiform in petricolum (®gure 7) but only narrowly fusiform in velutinum (®gure 13). Simulium (E.) petricolum is the `aureum J’ sibling species of cytologists (Leonhardt, 1985).