Fauna of simuliids (Diptera: Simuliidae) of the Tormes River hydrographic basin in central-western Spain and their responses to abiotic factors in their habitats

Delving into knowing the blackfly (Diptera: Simuliidae) species composition of Spain and their ecological requirements is crucial, due to their instrumental role in natural food webs as intermediaries in the flow of energy in aquatic ecosystems, and because of the haematophagic behaviour displayed by females of several species. The present study has analysed the abundance and distribution of the larvae and pupae of blackfly species in 105 sampling stations located in lotic water bodies of the provinces of Ávila, Salamanca, and Zamora of the Tormes River basin. The study has allowed to identify 24 species: 17 from Ávila, 13 from Salamanca, and seven from Zamora, classified in three genera (Metacnephia, Prosimulium, and Simulium), and five subgenera (Boophthora, Eusimulium, Nevermannia, Simulium, Wilhelmia). The results include four first records for Ávila province: Simulium (Nevermannia) armoricanumDoby & David, 1961, Simulium (Nevermannia) cryophilum (Rubtsov, 1959), Simulium (Nevermannia) naturale Davies, 1966, and Simulium (Simulium) variegatumMeigen, 1818. Among them, S. armoricanum shows the widest elevational range (900-1650 m a.s.l.), S. naturale shows the widest water temperature range (6-15 °C), and S. cryophilum stands out for inhabiting very fast waters. Blackfly communities were best discriminated by elevation and temperature. Our analyses allowed us to estimate the optima and tolerance ranges of the described species, with S. argygreatum, S. reptans, P. latimucro and P. tomosvaryi standing out for their preference for altitudes above 1000 m a.s.l., although with wide tolerance ranges. In terms of temperature, these two Prosimulium species were best represented at the coldest waters.