Chrysis mediata Linsenmaier 1951

56. Chrysis mediata Linsenmaier, 1951

Chrysis ignita var. mediata Linsenmaier 1951: 76. Lectotype ♀ (designated by Linsenmaier 1959: 154); Switzerland: Wallis (NMLS) (examined).

Chrysis mediata: Smissen 2010b: 191, Orlovskytė et al. 2010: 151, Dyntaxa 2013, Soon et al. 2014: 312.

Chrysis mediata mediata: Rosa & Soon 2012.

Material examined: * Latvia: Rūjiena, 17.VII.1973, 2 ♀♀ (V. Tumšs); Zaļenieki, 27.VI.1972, 1 ♀ (V. Tumšs).

Distribution. Estonia, * Latvia, Lithuania, Sweden.—Transpalearctic: palearctic region without Japan (Linsenmaier 1997).

Remarks. This taxon is closely related to C. solida, from which it is often difficult to distinguish morphologically, and many authors have considered them as conspecific (C. mediata sensu lato). According to identification keys, e.g. Smissen (2010a), C. mediata is larger and has a broader body. However, the main difference between the species is in their biology: C. mediata parasitizes ground nesting Odynerus species (mainly O. spinipes), while C. solida uses above ground nesting eumenines, probably mainly Ancistrocerus trifasciatus, as its host. DNA-barcoding studies have revealed no clear differences between the two species (Soon et al. 2014). It is thus possible that they in fact represent only intraspecific variation in size and host selection within a single species. In the studied area, C. mediata has a more southern distribution and is significantly scarcer than C. solida.

Rosa & Soon (2012) reported the species from Sweden based on six Swedish specimens preserved in Linsenmaier’s collection in NMLS and determined by Linsenmaier. The specimens have been collected from the provinces Scania, Uppland and Värmland. The determinations of the northern specimens should be checked, but the specimens from Scania are most likely correctly identified. Several records of the species have been made in recent years in southern Sweden. In the Baltic states the species is relatively rare, but widespread.

The occurrence of C. mediata in Denmark, Norway, Finland and Russian Fennoscandia is uncertain. It was reported from Denmark by Allearter.dk (2010), but the species was treated in the broad sense (including C. solida) (K. Runge Poulsen, in litt.). Also published records from Norway (Artsdatabanken 2010, Ødegaard et al. 2011: 64) present the species in the broad sense. Paukkunen et al. (2009: 6) reported the species from Finland based on two old Finnish specimens (collected from Ab: Karjalohja and N: Kirkkonummi), which are large enough to qualify as C. mediata. Two other specimens collected from Russian Fennoscandia (Ik: Valkjärvi) were also found in the collections of MZH. However, nothing is known of the habitats (or host species) from which they were collected. It cannot be ruled out that they actually represent abnormally large individuals of C. solida.