Checklist of the family Chironomidae (Diptera) of Finland

Abstract A checklist of the family Chironomidae (Diptera) recorded from Finland is presented.


Introduction
There are supposedly at least 15 000 species of chironomid midges in the world (Armitage et al. 1995, but see Pape et al. 2011) making it the largest family among the aquatic insects. The European chironomid fauna consists of 1262 species (Saether and Spies 2013). In Finland, 780 species can be found, of which 37 are still undescribed (Paasivirta 2012).
The species checklist written by B. Lindeberg on 23.10.1979 (Hackman 1980) included 409 chironomid species. Twenty of those species have been removed from the checklist due to various reasons. The total number of species increased in the 1980s to 570, mainly due to the identification work by me and J. Tuiskunen (Bergman andJansson 1983, Tuiskunen andLindeberg 1986). There has been a new rapid increase in the total number of species since 1998. I have reported 187 additional species, of which 8 have been new to science, and other researchers have reported 24 additional species. The chironomid fauna of all biogeographical provinces has been relatively well surveyed (Paasivirta 2012, including the trapping efficiency and the collectors).
Holotypes and paratypes exist for 87 species described from Finland. 23 species have been found only in Finland, thus making them putatively endemic species. Six of these species have only been found from the original type locality. 42 species have been found only from one collecting site in Finland.
Larvae of chironomid midges are found in all types of aquatic habitats. In addition, some species (130 species, 17%) specialize in semi-aquatic environments like wet moss on wetlands and shores of lotic waters. A total of 367 species have been identified from springs and the surrounding habitats in Finland. Sixteen percent of these species are associated with or specialized in springs and 25% are semi-aquatic species (Paasivirta 2007). One hundred and seventy aquatic species have been found from marine habitats, excluding river estuaries (Paasivirta 2000 and later additions). Sixty five additional species live in the mildly brackish water in the northern part of Bothnian Bay. There are only four strictly marine species.
The conservation statuses have been estimated for 667 Finnish chironomid species. Eleven species are classified as vulnerable (VU), 21 as near threatened (NT) and 6 species as lacking sufficient information (DD) (Penttinen et al. 2010). Since the chironomid midges have not been extensively studied and no long-term studies have been performed in Finland, the only useful criteria for the assessment of the conservation statuses have been either extent of occurrence or area of occupancy.
The nomenclature of the species list is consistent with Fauna Europaea (Saether and Spies 2013). Undescribed species are specified with appellations derived from the first collecting locality. For example Procladius sp. 2 "Palsa" was first found at a site called Palsa.
The list of Finnish chironomids (with bioprovincial distribution data) was last updated by Paasivirta (2012).

Excluded species
The numerous species that were reported by Hackman (1980), but are excluded from the current check-list, are not listed here. Reasons for deletions of those species are various, mainly due to misidentifications and nomenclatural changes.