Taxonomy
Paragus constrictus
Distribution
Species Biology
Preferred environment
Open ground; has been found on thinly vegetated limestone karst and bouldery, calcareous alluvial deposits/river margins; also in unimproved, alpine pasture and inland and coastal dune systems. In Ireland, P. constrictus has only been found on thinly vegetated limestone pavement at low altitude and in a calcareous coastal dune system. Low-lying limestone pavement is evidently a most suitable habitat for this insect, since it occurs in the Burren in many different localities and may be frequent where found. A predominantly bare-rock ground surface seems to be significant to this species, since it is largely replaced by the much more generally-distributed P. haemorrhous where a complete cover of ground vegetation occurs.
Adult habitat & habits
Flies within 1m of the ground, over bare rock and through ground vegetation, settling on foliage; as easily detected by sweeping as by direct observation.
Flight period
May and July/August. Larva: undescribed, but has been found on Hypochoeris radicata (Bartsch et al, 2009).
Flowers visited
White umbellifers; Crithmum maritimum, Dasiphora fruticosa, Potentilla erecta, P.fruticosa, Ranunculus.
Irish reference specimens
In the collections of NMI and UM
Determination
Simic (1986), Speight and Chandler (1995), Vujic et al (1998). As yet, this species may only be distinguished from P. tibialis in the male sex. In both sexes it shares with P. tibialis the feature of having entirely pale-haired abdominal tergites, so it is immediately distinguishable from P. haemorrhous (Mg). However, it is only distinguishable from P. tibialis in the shape of the parameres. These are illustrated by Simic (1986), Speight and Chandler (1995), Doczkal (1996a) and Vujic et al (1998). The latter authors provide the most complete set of figures. The relationship between this species and the enigmatic P. albipes Gimmerthal remains to be established. The type material of P. albipes (assuming it exists) does not seem to have been examined by any recent author, including Simic (1986). The general appearance of the male of P. constrictus is shown in colour by Bartsch et al (2009a). The same illustration is also used by those authors to illustrate the male of P. haemorrhous and P. tibialis.
Distribution
World distribution(GBIF)
As yet uncertain, due to confusion with other species, particularly P. tibialis (Fall.). So far, known from southern Sweden and Denmark (where it is almost entirely coastal in distribution: Bygebjerg, 2004), Ireland, Spain, Germany, the French Alps, Switzerland, Austria, Italy, the former Yugoslavia and Turkey; asiatic Russia. Neither of these two species, it should be noted, are known from the Pyrenees, or northern Spain or Portugal, though P. constrictus does occur in central Spain. Similarly, P. constrictus is unknown from Scandinavia. It is not yet known from Britain (though it would seem very likely to occur there). Localised as it is, its continued presence in Ireland is heavily dependent upon protection of the Burren limestone pavements from significant change.
Irish distribution
Attention was first drawn to the presence of this insect in Ireland by Speight (1978a), who at that time considered it to be a variant of P. tibialis. Speight & Chandler (1995) pointed out that all known Irish material of P. tibialis belonged in fact to P. constrictus. It seems that in Ireland P. constrictus is virtually confined to low altitude, limestone pavement areas. Although this means that it is known from only two 50km UTM grid squares it is frequent where it occurs and does not at present seem to be under significant threat. Like Cheilosia ahenea, with which it occurs in Ireland, P. constrictus gives every indication of being an early post-glacial relict species in Ireland, and, like C. ahenea, its closest-known continental stations to Ireland are in the vicinity of the Rhine.
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.