Stilbum princeps (Gray, 1832)

Rosa, Paolo, 2023, New records for the Indian cuckoo wasp fauna (Hymenoptera: Chrysididae) with description of two new species and remarks on types of Smith and Cameron, Journal of Natural History 57 (29 - 32), pp. 1396-1433 : 1429

Stilbum princeps (Gray in Griffith and Pidgeon, 1832)

( Figure 20A–20F )

Chrysis (Stilbium) princeps Gray in Griffith and Pidgeon 1832, p. 434. Holotype ♀; Australia: Melville Island (OUMUK).

Material examined

1♀: M J [= Melville Island?]/ Stilbum princeps Gray in Griff <red label handwritten by Cameron> [ OUMUK] .

Remarks

After the description, the name Stilbum princeps fell into oblivion. The species was correctly illustrated ( Figure 20B ) and described: ′In the sub-genus of chrysis Stilbium , we have established a species under the name princeps . It is of a bright rich green colour, entirely punctured, with a purplish tint in the middle of the thorax; the wings pale brown, with the nervures rather darker. This insect is from Melville Island̍ (Gray in Griffith and Pidgeon 1832, p. 434).

I assign the authorship of this species to Gray, as indicated in the title of the volume and as given in the captions of Figure 1 on Plate 77. The original combination is unclear, since the genus Stilbum is correctly spelled in the generic introduction at page 369 and in the Plate 77, where it is considered to be a valid genus; yet, it is spelled Stilbium in the description (as a subgenus of Chrysis ) and in the index on page 794 (where it is considered to be a valid genus). Because of this uncertainty, I consider the original combination of this species described in the genus Chrysis subgenus Stilbium (incorrect subsequent spelling), as given in the description at page 434. Problems in the correct recognition of authorships and original spellings in this volume were already noticed by other authors (eg Michener 1994).

This species is possibly a synonym of Stilbum splendidum (Fabricius, 1775) , the largest Australian species. However, a revision of the Oriental Stilbum is currently ongoing, and the synonymic list of Stilbum cyanurum (Forster, 1771) as proposed by Kimsey and Bohart ([1990] 1991) clearly includes several valid species, as already recognised by subsequent authors based on morphological characters (eg Mingo 1994; Linsenmaier1997) and DNA barcoding ( Rosa et al. 2023). In Australia, at least two valid species are known, Stilbum splendidum (Fabricius, 1775) and S. amethystinum (Fabricius, 1775) ; two additional Stilbum species are known for Australia: S. chrysocephalum concolor Linsenmaier, 1951 , and S. cyanurum pacificum Linsenmaier, 1951 . The occurrence of true S. cyanurum , considered by Kimsey and Bohart ([1990] 1991) to be the most common species in the genus and the only one present in Australia, should be confirmed.

Figures

Figure 1. Chrysis parviocula sp. n., holotype, ♀. A. Habitus, lateral view. B. Head, frontal view. C. Head and pronotum, dorsal view. D. Mesosoma, dorsal view. E. Metasoma, dorsal view. F. Habitus, posterior view. Scale bar: 1 mm.

Figure 20. Stilbum princeps (Gray, 1832), holotype ♀. A. Habitus, postero-lateral view. B. Illustration of the type from Griffith and Pidgeon (1832). C. Habitus, lateral view. D. Head, frontal view. E. Head and mesosoma, dorsal view. F. Metasoma, dorsal view. Scale bar: 5 mm.