Cheilosia ( Cheilosia ) urbana ( Meigen, 1822 )

Bot, Sander, Mengual, Ximo, Meutter, Frank Van de & Skevington, Jeffrey H., 2025, Review of the genus Cheilosia Meigen, 1822 (Diptera: Syrphidae) from the Caucasus, with the description of 14 new species, European Journal of Taxonomy 1023, pp. 1-181 : 138-140

Cheilosia ( Cheilosia) urbana ( Meigen, 1822)

Fig. 71

Syrphus urbana Meigen, 1822: 287 .

Eristalis praecox Zetterstedt, 1843: 801 . Syn. by Claussen & Speight (1999).

Cheilosia praecox – Tóth 1986: 94. — Peck 1988: 114.

Cheilosia urbana – Mengual et al. 2020: 21. — Żóralski & Bystrowski 2021: 26.

Differential diagnosis

Cheilosia urbana is a relatively small (body length: 6–8 mm) and narrow species. Cheilosia urbana is very similar to Cheilosia psilophthalma . The male of C. urbana is distinguishable from that of C. psilophthalma by the shape of the dorsal lobe of the postgonite (short and triangular in C. psilophthalma and narrow and long in C. urbana ) and by the frons (slightly swollen in C. psilophthalma but not swollen in C. urbana ). More differences with C. psilophthalma , which are true for both sexes, include the bicoloured claws, base orange, apex black (claws black in C. psilophthalma ), shiny sterna (slightly pruinose in Caucasian specimens of C. psilophthalma , in Europe shiny in both species), narrower parafacia and postpedicel dark orange to dark brown and wider than high (postpedicel orange and rounder C. psilophthalma ). In the female, the frons is narrower than in that of C. psilophthalma . Also similar to that of C. mutabilis , best distinguished by the metaleg: metatibia with distinct orange base and apex, in C. mutabilis metaleg black, with only base of metatibia yellow. Moreover, arista short pilose, with pile shorter than the width of arista at base, in C. mutabilis , arista with long pilosity, longer than or almost equal to the width of arista at base.

Material examined

Collected in 2018, 2019, 2021, 2022 and 2023; see Mengual et al. (2020) for detailed records from 2018.

Genetics

DNA barcodes of C. urbana cluster together in our NJ tree without a high support (BS <90%) and they form two groups with two different Barcode Index Numbers or BINs ( Ratnasingham & Hebert 2013): one with all European specimens (BIN BOLD:AAK0967; BS = 99.18.8%), except for a German specimen (CNCDB383-11) that is placed among the Caucasian specimens in a second group (BIN BOLD:AGA7172; BS = 94.7%).

Remarks

Except for one European specimen, all barcoded Georgian specimens of C. urbana group together in a separate cluster from the European specimens. We also found small morphological differences, mostly in the different pilosity colouration on the scutum and scutellum. The Caucasian male differs from the European male in having the scutum with mixed black and yellow pile as follows: the black pile dominates on the lateral parts, and the black and yellow pile have a roughly equal presence in the medial part of the scutum (in the European C. urbana the portion of black and yellow pile usually is roughly equal on the lateral parts or the yellow pile is predominant, while in the medial part of the scutum the yellow pile is more abundant with only scattered black pile). Moreover, the scutellum of the Caucasian specimens have short yellow pile and long black pile on the disc; whilst in European individuals the scutellum has short yellow pile and the long pile on the disc is either only yellow or black and yellow. We could not detect any differences in the male genitalia. In female Caucasian specimens, the pile on scutum is longer compared to European C. urbana , and usually some black pile is present in the anterolateral corner, usually absent in European C. urbana . Meier et al. (2022) critically argued the unsuitability to use the DNA barcodes for delimiting and describing species, and others explained the problems associated with the stand-alone-COI barcode taxonomy (see Ahrens et al. 2021). Moreover, Meier et al. (2022) clearly exposed that BINs do not always deserve a name. We like to emphasize the different clustering of the European and Caucasian specimens of C. urbana and their minor morphological differences; however, we are not confident in describing them as a separate species. Future research should focus on more (genetic) sampling in intermediate regions to better understand the current pattern.

Biology

During our expeditions, collected between 4 May and 12 July at an altitude between 1090 and 2800 m a.s.l. This is often one of the commonest species of Cheilosia in the alpine zone. Feeds on a large variety of flowers including trees ( Acer velutinum , Salix sp. ) and many low flowers (yellow and white crucifers, yellow composites, Caltha palustris , Ranunculus sp. , etc.).

Distribution

Western Palaearctic. Within the Caucasus known from Armenia, Georgia and Russia.