Biogeographia – The Journal of Integrative Biogeography

Data on the distribution of 238 European black fly taxa recorded in 97 operational geographical units (OGUs), of which 54 are European, were taken from published primary and secondary sources, summarised, numerically analysed and evaluated for chorotype identification. In continental Europe, 225 species have been recorded, of which 91 were registered only on the mainland. On the European islands, 70 species have been recorded, 13 of which are exclusively there; among them, 10 are European endemics (5 on the Mediterranean islands and 5 in Macaronesia). The individual species were recorded in 1–64 OGUs, the observed frequency distribution of species, according to the occupied OGUs, is strongly asymmetric and skewed to the right. This distribution does not fit the Fisher’s log-series distribution, the zero-truncated negative binomial, or the zero truncated Poisson distributions. The prevailing number of European black flies has a clear tendency to occupy small ranges. More than half of all species (128) are known from six or fewer OGUs (median = 6) and more than one-third of the species (35.5%) are from only 1–3 OGUs. One-quarter of all species, including 11 species complexes, are known from 14 or more OGUs (Q3 = 14). Only 12 species (~ 5%) are known from 39 or more OGUs; half of them being recognised species complexes. A wide range can be considered a property of a species complex, and by abduction, a taxon with such a range can be considered a species complex. Splitting a species complex into separate species can result in a range-splitting effect, i.e. the disintegration of the original large range into a number of overlapping or non-overlapping smaller species ranges can result in existing chorotypes disappearing or new ones arising. Cluster analysis C1 (CLC = complete linkage clustering, Baroni-Urbani & Buser index of similarity) provided 30 significant clusters, 26 of them isolated, with 1 to 24 species each (median = 5.5). Cluster analysis C2 (CLC, Jaccard’s index of similarity) provided 53 significant clusters, 26 of them isolated, with 1 to 20 species each (median = 3). The cophenetic correlation coefficient r_coph between C1 and C2 was 0.8015, indicating a high agreement between the two classifications. In an expert assessment based on cluster analysis, 29 global chorotypes were distinguished. According to the overall range extent and its location on the continents, the chorotypes were arranged into seven groups as follows: Holarctic (26 spp., American–European, Pan-Holarctic, Holarctic boreal, Palaearctic–East Beringian chorotypes), Palaearctic (40 spp., Pan-Palaearctic, Euro–Asian, Sibero–European), West–Central Palaearctic group (10 spp., Central Asian–Euro–Mediterranean, Central Asian–Turano–Euxinian, Turano–Caucasian), Western Palaearctic (18 spp., Euro–Mediterranean, Mediterranean–Macaronesian, Macaronesian–West Mediterranean), European (86 spp., Pan-European, Western European, Northern European, Central European, Apenninian, Balkan, Eastern European), Mediterranean group (53 spp., Pan-Mediterranean, West Mediterranean, East Mediterranean, Euxinian, Crimean, Caucasian), and the Macaronesian group (5 spp., Azorean, Madeiran, Canarian). The main result of the analysis of ranges of European black flies is the description of 29 global chorotypes. The analysis shows that the chorological structure of the European black fly fauna is complex and it varies significantly in different parts of the continent and adjacent islands. This can be the start for further zoogeographical, phylogeographical and other analyses in this area of research.