Hedychrum rutilans Dahlbom, 1854

Rosa, Paolo & Xu, Zai-fu, 2015, Annotated type catalogue of the Chrysididae (Insecta, Hymenoptera) deposited in the collection of Maximilian Spinola (1780 - 1857), Turin, ZooKeys 471, pp. 1-96 : 44-46

Taxon classification Animalia Hymenoptera Chrysididae

Hedychrum rutilans Dahlbom, 1854

Hedychrum rutilans : Dahlbom 1854: 76.

Type locality.

"Habitat in Anglia, Germania, Gallia, Hispania, passim".

Material.

Syntypes 2 ♂♂, ♀. Hedychrum rutilans , Meg. var. c, Dhlbm. - Hedychrum regium , Lep. Liguria.

Catalogue Casolari & Casolari Moreno. Hedychrum rutilans , 186, 145, 0, 3 (box 50).

Remarks.

Dahlbom (1854) described Hedychrum rutilans based on a syntype series subdivided into three varieties (var. a, var. b, var. c). The syntypes listed by Dahlbom are housed in the following museums: Hedychrum rutilans var. a: NHMW (teste Kollar), MNHU (teste Klug), ZMUC (teste Drewsen); Hedychrum rutilans var. b: MNHU (teste Klug); Hedychrum rutilans var. c: MRSN (Spinola coll., " Hedychrum regium Pellet. secund. Spin. in litt." e " Hedychrum intermedium Mus. Spinolae"). These syntypes are still housed in the listed museums. Morgan (1984: 10) designated the lectotype on a specimen collected by Zeller and housed in the Dahlbom Collection at LZM. This specimen is labelled: " Hedychrum rutilans Megerl. Dahl. var. a". According to the Art. 74.2 of the Code this specimen is not a syntype, therefore it loses its status of lectotype.

The name Hedychrum rutilans is a matter of conflict between entomologists. The history of the names Hedychrum rutilans and Hedychrum intermedium is long and complicated. Linsenmaier (1959, 1968, 1997a, 1997b, 1999) used the name Hedychrum intermedium Dahlbom, 1845, instead of Hedychrum rutilans Dahlbom, 1854, as many other authors did in the past. In various European collections, specimens belonging to this species are still found under the name Hedychrum intermedium . Many entomologists, in fact, still follow Linsenmaier’s interpretation. Linsemaier never accepted the synonymy proposed by Morgan (1984: 8) and that was accepted by Kimsey and Bohart (1991). Morgan (1984), in fact, discovered that the holotype of Hedychrum intermedium belongs to the genus Holopyga . Unfortunately, Morgan did not provide any further information on the species nor in which museum he examined this type. After an extensive tour in the European museums, we found out that the type of Hedychrum intermedium is housed in LZM. Kimsey and Bohart (1991: 232) wrote that they examined this holotype at MNHN, and later Linsenmaier (1997a) argued that Dufour’s specimens are housed at MNHN. After studying all relevant type material at MNHN and after having conducted an extensive literature survey, we are confident in writing that not one specimen labelled " Holopyga intermedia Gall. Dufour"," Holopyga intermedia " or " Hedychrum intermedium " is housed at MNHN. In the "General collection" in MNHN there are two specimens labelled " Hedychrum rutilans " and "Coll. Dufour 1834". These two specimens had not been studied by Morgan, yet they were listed by du Buysson (1898: 521) and mentioned as possible "types" by Linsenmaier (1997a), since their labels match the original data cited by Dahlbom (1845). Based on the erroneous information given by Kimsey and Bohart (1991) on the type depository, Linsenmaier (1997a) did not accept Morgan’s interpretation and stated that labeles must have been exchanged. Moreover, Linsenmaier argued that it was not possible that Dahlbom, who described the genus Holopyga in the same paper, would have confused it with Hedychrum .

At the beginning of our studies, we agreed with Linsenmaier and we also noticed that no other European Hedychrum has the described colour "♂ thorax antice viridis postice cyaneus"; only the male of Holopyga ignicollis sensu Linsenmaier (= Holopyga aureomaculata Abeille) shows a similar colouration. We concluded that Morgan probably confused the type of Hedychrum intermedium with the type of another mysterious species described in the same work by Dahlbom on Dufour material collected in France: Holopyga nitidula . In this sense, the examination of the Dahlbom collection in LZM was fundamental. The specimen cited by Morgan is indeed the type of Hedychrum intermedium . This confirmation is not only based on the precise labels, already cited by Morgan, but also on the morphological and chromatic characteristics given by Dahlbom. This specimen is a male of Holopyga fervida (Fabricius, 1781) with colouration similar to Holopyga fervida var. taorminensis Trautmann: pronotum and mesonotum light bluish-greenish, in contrast with the rest of the mesosoma. But the most important characteristic is the punctuation on the mesosoma: 'pronotum et dorsulum nitida sparse punctata’. No Hedychrum species has this peculiar punctuation, but Holopyga fervida has it.

It is not strange that Dahlbom in 1845 identified the male of Holopyga fervida as Hedychrum . In fact, Dahlbom in 1854 described again the males of Holopyga fervida as Hedychrum chloroideum , based on specimens entirely green or bluish-green, without any contrasts in the colouration of the mesosoma.

It seems that Linsenmaier was influenced by Richards (1935: 158). This important author received the type of Hedychrum intermedium and Hedychrum rutilans by Kemner (Lund): "Through the kindness of Dr. N. A. Kemner, we have examined the type of Hedychrum rutilans Dahlbom, 1854. It is a female bearing two labels (1)" Z. Mer."or"L. Mer."and (2)" Hedychrum rutilans . Megerl. Secund. M.B. Dhbm. var. a."The specimen agrees with Dahlbom’s description of his var. a. (i.e. the typical form of the species) and also with the modern interpretation of his name (e.g. Trautmann, 1928). Dr. Kemner also sent what is almost certainly the type of Hedychrum intermedium Dahlbom, 1845. This species was described in 1845 from France but in 1854 Dahlbom dropped the name intermedium ; his var. c. of Hedychrum rutilans agrees with the earlier described intermedium. The probable type of intermedium is a male bearing two labels: (1)" Hedychrum rutilans Dhlbm. var. c."and (2) " Hab.? Fontainebleau Collect. Barbut."This specimen agrees with the original description of intermedium . It is a male of one of the greenish forms of Hedychrum rutilans . It may be described as follows: - Green; slight trace of copper on central lobe of mesonotum. Postscutellum and propodeum blue. Abdomen green, disc of second tergite and whole of third, copper-tinged. Legs blue. Venter of abdomen black. In my opinion, therefore, the species should be known as Hedychrum intermedium Dahlbom, 1845".

Nevertheless, Richards did not realize that none of the examined specimens was truly a type. In particular, Hedychrum intermedium did not match the original type, since it was collected at Fontainebleau by Barbut and not by Dufour. This should be the reason different authors, including Linsenmaier, considered Hedychrum intermedium had priority over the name Hedychrum rutilans .

In conclusion, we formally propose here the new synonymy: Hedychrum intermedium Dahlbom, 1845 = Holopyga fervida (Fabricius, 1781). The valid name for one of the most common European species is therefore Hedychrum rutilans Dahlbom, 1854, as already stated by Morgan (1984).

Current status.

Hedychrum rutilans Dahlbom, 1854.