Taxonomy
Cheilosia vernalis
Distribution
Species Biology
Preferred environment
Open ground/forest; dune systems, humid, oligotrophic and eutrophic unimproved pasture; Molinia grassland of acidic fen subject to seasonal flooding; grassy clearings in deciduous forest and upwards through montane grassland into alpine grassland. This species occurs in a number of different ecosystem types in Ireland, as elsewhere in Europe. It also exhibits a wider range of phenotypic variation than is characteristic for related species, giving rise to speculation that it may be a mixture of two or more species. However, repeated attempts at subdividing C. vernalis have so far been unsuccessful, and on the basis of available information it would seem that, in Ireland at least, only one species is involved. Here, it occurs in coastal dune systems, unimproved grassland and in grassy open areas in deciduous woodland. It occurs on both well-drained sites and under conditions of poor site drainage, though it is not usually found in the karst limestone grassland of the Burren, for instance. It is one species characteristic of winter-flooded Molinia grassland, at sheltered locations. There it may be met with very early in the year and these early specimens are usually rather large, pale-haired and with pale antennae - seemingly very different from the standard summer brood individuals.
Adult habitat & habits
Low-flying, over ground vegetation; males hover at 1-3m, in small clearings and at sheltered spots.
Flight period
April/October, with peaks in May/June and August. Larva: undescribed, but known to be an internal feeder in the stems of Achillea, Matricaria and Sonchus oleraceus and in the involucre of Tragopogon (Bankowska, 1980; Torp, 1984). The morphology of the chorion of the egg is figured by Kuznetzov (1988).
Flowers visited
White umbellifers; Caltha, Cirsium arvense, Leontodon, Leucanthemum, Menyanthes, Prunus spinosa, Ranunculus, Salix, Senecio, Taraxacum.
Irish reference specimens
In the collections of NMI and UM
Determination
Bartsch et al (2009a); van der Goot (1981). In recent texts it has more than once been suggested that, as at present recognised, C. vernalis comprises more than one species. However, no satisfactory basis for subdividing the species has yet been demonstrated and the male terminalia of the various different variants appear identical. Van Veen (2004) attempts to segregate some elements of the C. vernalis complex, such as C. rotundiventris (Becker) and C. ruficollis (Becker). But Stahls et al (2008) subsequently identified these two taxa as synonyms of C. vernalis, from a comparative genetic study. Milankov et al (2002) studied genetically a number of Balkan populations of C. vernalis collected in various habitats, but concluded that the variation exhibited was intra-specific, though significant. Spring brood specimens are typically entirely, or predominantly, brown haired and frequently have the third antennal segment orange, while summer specimens tend to be predominantly black-haired, with the third antennal segment dark brown. The specimens with orange antennae are not possible to determine correctly using existing keys. One species which is extremely similar to C. vernalis although differing distinctly in characters of the male terminalia, is C. sootryeni Nielsen (1970). This latter species may well have been confused with C. vernalis by some authors, since its description seems to have been largely overlooked. C. sootryeni is included in the keys provided by Bartsch et al (2009b), Haarto and Kerppola (2007) and van Veen (2004). Another species extremely similar to C. vernalis, but nonetheless distinct, according to genetics data presented by Stahls et al (2008), is C. reniformis (Hellen). For distinctions between C. vernalis and C. reniformis see the C. reniformis species account. Other species that can be extremely difficult to separate from C. vernalis are C. cynocephala and C. melanura: it can be impossible to decide to which of these three taxa individual specimens belong, using the morphological features currently employed to separate them. An extended discussion of intraspecific variability in adults of C. vernalis is provided by Stahls et al (2008), but their study does not encompass C. cynocephala and C. melanura. The adult of C. vernalis is illustrated in colour in Bartsch et al (2009b), Stubbs and Falk (1983) and Torp (1994).
Distribution
World distribution(GBIF)
Fennoscandia south to Iberia; from Ireland eastwards through central and southern Europe (Italy, former Yugoslavia) to Turkey and European parts of Russia and on through Siberia to the Pacific coast. This is another Cheilosia species that is very generally distributed both in Europe and in Asiatic parts of the Palaearctic region.
Irish distribution
Given as occurring in Ireland in Coe (1953). As at present defined, C. vernalis is widely distributed and not uncommon in Ireland. But if it is demonstrated that the variability of this species masks the existence of more than one valid taxon, the status of C. vernalis in Ireland would require re-assessment.
Temporal change
Records submitted to Data Centre in 2024
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References
Publications
Speight, M. C. D. (2008) Database of Irish Syrphidae
(Diptera). Irish Wildlife Manuals, No. 36. National Parks and Wildlife Service.
Department of Environment, Heritage and Local Government, Dublin, Ireland.
Speight, M.C.D. (2014) Species accounts of European
Syrphidae (Diptera), 2014. Syrph the Net, the database of European Syrphidae,
vol. 78, 321 pp., Syrph the Net publications, Dublin.