Simulium (Eusimulium) velutinum (Santos Abreu)

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 : 2100-2101

Simulium (Eusimulium) velutinum (Santos Abreu)

Material from breeding sites

Gomera: Site G 5— 2 pupae, 11 larvae (6 June 1990) ( RWC). La Palma: Site LP 1— 1 pupa (17 April 1981) ( RWC) .

Remarks

This is the most generally distributed member of the Simulium aureum group (~ Eusimulium ) in the western Palaearctic, occurring widely in southern Europe, the Mediterranean islands and North Africa. La Palma is the type locality and Gomera the only other island of the Canaries from which the species has been identified (new record here). However, Simulium tenerificum , endemic to Tenerife and Gomera, is very closely related and it is not entirely certain that the two nominal species are distinct (see under tenerificum ). The first record for velutinum from Gomera here given is based on two pupae from aqueduct site G5, which satisfactorily fit the diagnostic key characters given above.

Simulium velutinum has been recognized as equating with aureum ‘I’ of cytotaxonomic literature, a sibling first characterized by Leonhardt (1985) but

foreshadowed and tagged as ‘I’ in an aureum group phylogram published by Dunbar (1965). Leonhardt identified the sibling in material from Britain and Italy (Leonhardt, 1985). Chromosomal data are still lacking for the Canary Islands and are much needed to clarify the identity cytologically of true S. velutinum from its type locality, the island of La Palma; however, the likelihood of finding larvae here is very remote because of the almost total absence of running water in this island

today. Two aureum group larvae collected ( RWC) in the natural ravine stream below La Cumbrecita, La Palma, on 17 April 1981, were identified by Leonhardt (1985) as sibling ‘L’ ( tenerificum ), not sibling ‘I’. This was surprising inasmuch as the one pupa in the La Cumbrecita sample seems unambiguously to be S. velutinum . Unlike S. tenerificum , the head plate and thoracic dorsum bear abundant microtubercles and the cocoon has the shape typical of S. aureum group cocoon, i.e. the anterior margin is regularly concave seen from above and almost straight seen

in profile (figures 29, 30); the gill of this pupa is also typical (figure 25).

The old adult flies from La Palma on which Simulium velutinum , and its nominal specific synonyms (pseudolatipes Santos Abreu and nigripes Santos Abreu), were originally described by Santos Abreu (1922)—data provided in Crosskey (1988b: 337)—conform completely to the characters of velutinum as it has now been widely recognized in European taxonomy, leaving no doubt (at least at morphological level) which western Palaearctic aureum group species should correctly be called velutinum .

It appears likely that there is occasional hybridization between species of the aureum group ( Eusimulium ) in the Canaries because some specimens have been found which share typical S. velutinum characters with characters of the two endemic species, S. tenerificum and S. guimari . More detail is given below under the remarks for these species.