Coloration of stinging insects is often based on contrasted patterns of light and black pigmentations as a warning signal to predators. However, in many social wasp species, geographic variation drastically modifies this signal through melanic polymorphism potentially driven by different selective pressures. To date, surprisingly little is known about the geographic variation of coloration of social wasps in relation to aposematism and melanism and to genetic and developmental constraints. The main objectives of this study are to improve the description of the colour variation within a social wasp species and to determine which factors are driving this variation. Therefore, we explored the evolutionary history of a polymorphic hornet, Vespa velutina Lepeletier, 1836, using mitochondrial and microsatellite markers, and we analysed its melanic variation using a colour space based on a description of body parts coloration. We found two main lineages within the species and confirmed the previous synonymy of V. auraria Smith, 1852, under V. velutina, differing only by the coloration. We also found that the melanic variation of most body parts was positively correlated, with some segments forming potential colour modules. Finally, we showed that the variation of coloration between populations was not related to their molecular, geographic or climatic differences. Our observations suggest that the coloration patterns of hornets and their geographic variations are determined by genes with an influence of developmental constraints. Our results also highlight that Vespa velutina populations have experienced several convergent evolutions of the coloration, more likely influenced by constraints on aposematism and Müllerian mimicry than by abiotic pressures on melanism.

The taxonomy and biogeography of potter wasps with a petiolate metasoma occurring in the Indonesian Archipelago are reviewed. Literature review and specimens examination were carried out for the present study. Within the Eumeninae, the wasps with a petiolate metasoma distributed in the region have been more or less well studied compared with those with a non-petiolate metasoma, but their generic affinities and the concepts of some species yet remain unestablished. A total of 80 species belonging to 16 genera of the “petiolate metasoma” are known to occur from the region. Sumatra, Java, Bali and Borneo have mainly Oriental eumenine fauna, including several area- specific species of the Oriental genera. New Guinean fauna is comprised of Papua-Australian species of the widely distributed genera, together with widely distributed species and species endemic to New Guinea. The Wallacean fauna is constituted mainly with the area-specific species in the rather widely distributed genera; in the western part of Wallacea, they are represented mainly by widely distributed genera, together with Oriental genera; in the eastern part of Wallacea, they are constituted mainly by area endemic species of widely distributed Oriental genera. Widely distributed species generally show a wide range of variation in the marking patterns, and occurs sympatrically in some areas, even the peripheral populations usually characterized by the island(s)-specific marking patterns. Sympatric occurrences of forms with quite different color patterns in widely distributed species need further study to establish their taxonomic status, namely whether they are variations within a given area or different species.

Twenty species and six subspecies of nine genera of eumenine wasps with a petiolate metasoma occurring in the Lesser Sunda Islands are listed. New synonymies are proposed for Delta campaniforme campaniforme (Fabricius 1775) (=D. campaniforme gracilior Giordani Soika 1986, syn. nov.) and D. nigriculum Giordani Soika 1986, stat. nov. (=D. campaniforme rendalloide Giordani Soika 1993, syn. nov.). Eumenes piriformis de Saussure and E. inconspicuus Smith are newly recorded from the Lesser Sunda Islands; E. pius Giordani Soika, D. nigriculum Giordani Soika, D. pyriforme (Fabricius), D. sciarum (van der Vecht), Pareumenes nigerrimus van der Vecht, and Labus vandervechti Giordani Soika, are newly recorded from some islands of the Lesser Sunda. Hitherto unknown male of P. nigerrimus is described.

The taxonomic history and current taxonomic status of the presocial potter wasp genus Calligaster de Saussure, 1852, at generic and species levels are reviewed. The hitherto-unknown female of Calligaster viridipennis Giordani Soika, 1960, is described based on specimens newly collected in Central and Southeast Sulawesi. A key to species is also provided.

Wasps of the genus Eustenogaster van der Vecht, 1969, with 17 species currently recognized, are distributed from the Indian subcontinent in the west to the Philippines, Sulawesi Island and Java Island in the east. Two new species of hover wasp genus Eustenogaster (E. multifolia sp. nov., E. sumatraensis sp. nov.) are described from specimens collected in Sumatra Island. The female of E. vietnamensis occurring in Vietnam are described for the first time. The lectotypes of Paravespa eva Bell, 1936 and Ischnogaster ornatifrons Cameron, 1902 are designated. The new taxonomic status is proposed for Stenogaster eximioides Dover and Rao, 1922 as a good (=valid) species of Eustenogaster. The synonymy of Ischnogaster ornatifrons Cameron, 1902 with Eustenogaster micans (de Saussure, 1852) has been confirmed. A revised key to species and a taxonomic and distributional checklist of all the species of Eustenogaster are provided.