This taxon is distributed mainly in Caucasia, Transcaucasia and the Balkan countries including the island of Rhodes, and its occurrence in Turkey has been known previously (Crosskey and Zwick 2007). The first record from Anatolia was by Kazancı and Clergue-Gazeau (1990), as P. pronevitschae, from three different lotic systems. Crosskey and Howard (2004) synonymized pronevitschae with rachiliense. Crosskey and Zwick (2007) reported this species from seven sites in northwestern and southeastern Anatolia. We identified our material as P. rachiliense, using the illustrations and descriptions by Terteryan (1968) and Crosskey and Malicky (2001). Adler and Şirin (2014) chromosomally showed that populations in western Turkey are a cytoform of P. rachiliense, probably different from true P. rachiliense. We compared our larvae and pupae with the material in the study of Adler and Şirin (2014)​, and did not find structural differences.

We report this species for the first time from Turkey. The taxonomy of the genus Metacnephia requires revision. In Turkey, only two species, M. lyra and M. subalpina, of this genus have been known until now (Kazancı and Ertunç 2008). The pupal features of our specimens are similar to those of M. subalpina, reported from four localities in Anatolia, one in the northwestern and three in the eastern and southeastern parts of the country, by Crosskey and Zwick (2007). Metacnephia subalpina was described by Rubtsov (1956) as a variety of M. nigra, but Terteryan (1968) elevated it to species. According to Crosskey and Zwick (2007), the relationship of M. subalpina and M. nigra remains unsettled because of the problem of the true identity of M. nigra; the authors could not resolve the ambiguities. They noted that Yankovsky (1995) (pp. 4, 50) treated subalpina and nigra as synonyms before reverting [Yankovsky (2003)] to treating them as separate species. Crosskey and Zwick (2007) used the name subalpina for their material because it conformed in the shape of the ventral plate and pupal gill with Djafarov’s illustrations of M. subalpina. Another species, Metacnephia uzunovi, described by Kovachev (1985) from Bulgaria, confuses the taxonomic situation by having similar structural characters to M. nigra. We have doubts about its validity. We recognize M. nigra as a species complex, following the recommendation of P.H. Adler (pers. comm.) who noted the similarity with Rubtsov’s (1956, fig. 113) variety, saxicola, of M. nigra. Adler suggested that we use the name M. nigra for our material, with reference to Rubtsov’s (1956) variety saxicola, as a conservative approach that will provide future workers with an idea of the morphology of our material until the correct name of the species can be determined. M. nigra is known from Azerbaijan (Nakhichevan), Romania, Russia (Caucasus) and Turkmenistan (Adler and Crosskey 2015).

Simulium erythrocephalum is the most abundant species of the subgenus Boophthora in the western Palearctic and is reported from the Far East of Asia (Adler and Crosskey 2015). Breeding sites of S. erythrocephalum are generally weedy, lowland streams and rivers, such as the Danube (Germany, Serbia), the Spree (Germany), the Warta (Poland), and the Morava (Czech Republich). In Central Europe, it occurs in various flowing-water systems such as lowland streams, outflows from ponds, irrigation constructions and large rivers (Werner and Kampen 2012). It can develop large populations and become a serious pest and nuisance to humans and farm animals (Ignjatović-Ćupına et al. 2006) In Anatolia, it has been recorded by several authors. Sirin and Sahin (2005) found it at two sites in the Sakarya river basin for the first time in Turkey. Kazancı and Ertunç (2008) stated that S. erythrocephalum lives in the Büyük Menderes river basin in southwestern Anatolia. It is recorded by Gazyağcı and Aydenizöz (2011) from the Kızılırmak River in Kırıkkale Province. The latest record for S. erythrocephalum from Turkey was given by Şirin et al. (2014) from Sakarya and Kocaeli Provinces. According to the keys of Knoz (1965) and Bass (1998), the species can be identified by a pair of inconspicuous dorsolateral papillae on each segment of the larva, the pattern of the larval head capsule, the branching pattern of the six pupal gill filaments, and the shape of the pupal cocoon. The male genitalia of our specimens conform to the description by Rubtsov (1956)​.

Simulium petricolum is one of three species in the S. aureum species group of the subgenus Eusimulium in Anatolia. The others are S. angustipes and S. velutinum. The first record of S. petricolum from Turkey was published by Kalafat and Şirin (2011). Gazyağcı and Aydenizöz (2011) recorded it from the Kızılırmak River in Kırıkkale Province. It was also reported from eastern Marmara Region by Şirin et al. (2014). Simulium petricolum occurs in southern Europe and especially in the Mediterranean countries (Crosskey and Malicky 2001). According to Crosskey and Malicky (2001), the species is not reliably distinguished from S. velutinum in the aquatic stages, adults being required for positive identification. Our specimens conform in genitalia to the descriptions by Crosskey and Malicky (2001) and Day et al. (2010)

Simulium velutinum occurs in most of Europe but is especially common in the Mediterranean subregion from the Canary Islands (type locality) to Israel and Jordan (Crosskey and Malicky 2001). According to Kazancı and Ertunç (2008)​, S. velutinum also inhabits southwestern Anatolia. Its existence in Turkish Thrace is, therefore, expected. Identification of this species is most reliably based on genitalia: the ventral plate of the male is smaller and more triangular and the spermatheca of the female is without the usual sclerotized nipple-like extension that is found in the other members of the S. aureum group.

Simulium cryophilum is a member of the S. vernum species-group, which includes more than one-fourth of the nominal species in the western Palearctic. According to Crosskey and Malicky (2001), there are difficulties in identification of the species of the S. vernum group. Another taxonomic difficulty is that S. cryophilum is a composite of at least two chromosomally distinct sibling species (Hunter 1987; Adler et al. 1999). We, therefore, refer to it in Turkey as the S. cryophilum complex. We found it in two streams in the southern part of our study region. The main structural features of our material were in the pupal stage: (1) gill with all four filaments held closely together and about equal in thickness (Bass 1998; Crosskey and Malicky 2001); (2) upper pair of gill filaments branched horizontally (Jedlićka et al. 2004); (3) upper and lower pairs of filaments on short common stalks equal in length (Bass 1998; Jedlićka et al. 2004); (4) thoracic microtubercles dense and rounded and thoracic trichomes simple (Bass 1998); and (5) cocoon fully covering pupa and with a short anteromedian horn. In our larvae, the postgenal cleft was clearly defined and pentagonal, conforming to the description by Bass (1998)​.

This species occurs in the southwestern Palearctic from Iberia through central and southern Europe to the Transcaucasus and northern Middle East, and is present in northwestern Africa and most of the larger Mediterranean islands. It is common and widespread in Anatolia (Crosskey and Zwick 2007). Simulium bezzii, like Simulium kerisorum, also known from Turkey, has six pupal gill filaments, in contrast to most other species of the S. bezzii-group, which generally have eight filaments. It can be distinguished by large fenestrations posterior to the cocoon rim. Crosskey and Zwick (2007) stated that S. kerisorum is not a valid species and thought that the Turkish record of Kazancı and Clergue-Gazeau (1990) is questionable. The chromosomes of Simulium bezzii have been studied (mainly by Kachvoryan (1988), as Tetisimulium condici) but not those of S. kerisorum, and cytological comparison of the two nominal taxa is desirable (Crosskey and Zwick 2007​).

The type locality of Simulium bukovskii is in Crimea (Ukraine) and its distribution ranges from the Balkans to Armenia. It was recorded from Turkey by different authors (Crosskey and Zwick 2007). Furthermore, it is similar to S. degrangei Dorier and Grenier (1960), which is also common in most countries of southern Europe. Crosskey and Zwick (2007)​ emphasized the similarity of the two species and that synonymy should be considered.

Simulium (Simulium) noelleri is a well-known simuliid, with a general preference for outlets. It is distinguished by the branching arrangement of the pupal gills (3+3+2 or 3+2+2+1). We encountered it at one locality, an outlet from a small pond. Our pupae have eight gill filaments arranged as 3+3+2, and the apotome pattern of the larval head capsule is like an ill-defined “H”, as described by Bass (1998). Although, S. noelleri is widespread in the Palaearctic, there are rwo records of it in Turkey, from the Sakarya River basin (Sirin and Sahin 2005) and East Marmara Region (Şirin et al. 2014​).