Hedychrum Latreille, 1802

Rosa, Paolo, Heim, René & Bernasconi, Marco Valerio, 2022, The Palaearctic types of Chrysididae (Insecta, Hymenoptera) deposited in the Linsenmaier collection. Part 3. Elampini: genus Hedychrum Latreille, Zootaxa 5195 (1), pp. 1-23 : 3

Genus Hedychrum Latreille, 1802

Hedychrum Latreille, 1802: 317 .

Type species: Chrysis lucidula Fabricius, 1775 (= Sphex nobilis Scopoli, 1763 ), by monotypy.

Hedychrum Latreille, 1802 is the second largest genus in the tribe Elampini , after Hedychridium Abeille de Perrin, 1878 . It includes about 150 species known worldwide, the majority of which occur in the Palaearctic region and Afrotropical region ( Kimsey & Bohart 1991). The European fauna consists of 17 species only and several subspecies, some of which probably would deserve species rank ( Rosa & Soon 2012; Mitroiu et al. 2015); overall, about 60 species are known from the Palaearctic region.

The genus Hedychrum includes robust species with a body length ranging from 4 to 10 mm. Diagnostic morphological features for the identification of the genus are the following: the apically bifid tarsal claws; the enlarged hindfemur sexually dimorphic, with anterior surface reticulate, non-metallic brown with dense pubescence in males, glabrous and shiny metallic in females; the third tergum subapically swollen and with a lateral tooth; fore wing medial vein straight or slightly curved medially; the presence of an apicomedial tubercle on the third sternum in some females; the presence of a meso- and a metatibial groove. Some Palaearctic species show chromatic sexual dimorphism, with thorax bicoloured in the female and uniformly green or blue in the male.

The genus was never subdivided into species groups by Linsenmaier (1959; 1968, 1987, 1999), even though he considered Wollmannia Mocsáry, 1909 as a subgenus with Hedychrum (Wollmannia) concinna Mocsáry, 1909 as the only species included, characterised by the bidentate apical margin of the third metasomal tergum ( Linsenmaier 1968). Recently, Rosa (2019) established the H. cirtanum species group, characterised by species with metascutellum posteriorly slightly projecting over the propodeum, including a species from Pakistan named Hedychrum linsenmaieri Rosa, 2019 . The mucronate metascutellum is considered a rare derived feature in the tribe Elampini ( Kimsey & Bohart 1991) and only a few Hedychrum species worldwide have the metascutellum slightly projecting posteriorly over the propodeum, e.g. the Malagasy H. mucronatum Zimmermann, 1956 .