Review of the genus Megascolia Betrem, 1928 (Hymenoptera, Scoliidae)

A taxonomic review of the genus Megascolia Betrem, 1928 is given. To date, the genus is composed of two subgenera, Megascolia Betrem, 1928 and Regiscolia Betrem & Bradley, 1964, gathering 15 described species. However, the large size of the species and the number of submarginal cells are not sufficient to support the grouping of all the species into a single genus and there are profound morphological differences between the species of the two sub-genera. The subgenus Regiscolia Betrem & Bradley, 1964, stat. nov. is therefore elevated to the generic level. Furthermore, the discovery of a new species sharing unique characteristics with Megascolia speciosa (Smith, 1858) has made it possible to highlight several criteria specific to these two species which clearly separate them from all other known Scoliini genera. A new genus, Gigascolia Castagnet & Cabon, gen. nov., is therefore described to take Megascolia speciosa (Smith, 1858) and a new species from Sulawesi (Indonesia), Gigascolia speciosissima Castagnet & Cabon, sp. nov. This generic restructuring leads to the creation of the following new combinations and status: Gigascolia speciosa (Smith, 1858), comb. nov., Regiscolia alecto (Smith, 1858), comb. nov., R. almoraensis (Gupta & Jonathan, 2003), comb. nov., R. azurea (Christ, 1791), comb. nov., R. bidens (Linnaeus, 1767), comb. nov., R. capitata (Fabricius, 1804), comb. nov., R. fulvifrons (Saussure, 1855), comb. nov., R. maculata (Drury, 1773), comb. nov., R. rubida (Gribodo, 1893), comb. nov. and R. splendida (Saussure, 1858), comb. nov. The following synonymies are established: Megascolia procer (Illiger, 1802) = Triscolia procer var. sumatrensis Gribodo, 1893, syn. nov. = Scolia (Triscolia sectio Megascolia) procer var. sarawakensis Betrem, 1928, syn. nov. = Megascolia (Megascolia) procer javanensis Betrem & Bradley, 1964, syn. nov., Megascolia velutina (Saussure, 1859) = Scolia ducalis Smith, 1861, syn. nov. = Scolia intrudens Smith, 1862, syn. nov. = Triscolia velutina keyensis Micha, 1927, syn. nov., Regiscolia alecto (Smith, 1858) = Scolia (Triscolia) philippinensis Rohwer, 1921, syn. nov., Regiscolia azurea (Christ, 1791) = Scolia rubiginosa Fabricius, 1793, syn. nov. = Scolia (Scolia) magnifica Saussure, 1859, syn. nov. = Triscolia vespillo Gribodo, 1893, syn. nov. = Triscolia democratica Micha, 1927, syn. nov. = Scolia (Triscolia sectio Triscolia) hageni Betrem, 1928, syn. nov. = Scolia (Triscolia sectio Triscolia) azurea cochinensis Betrem, 1928, syn. nov. = Scolia (Triscolia) azurea christiana Guiglia & Betrem, 1958, syn. nov., Regiscolia bidens (Linnaeus, 1767) = Scolia (Triscolia) bidens var. rufohirta Dusmet, 1930, syn. nov., Regiscolia capitata (Fabricius, 1804) = Triscolia patricialis brunneipennis Micha, 1927, syn. nov. = Scolia (Triscolia sectio Megascolia) patricialis var. leefmansi Betrem 1928, syn. nov. = Megascolia (Regiscolia) capitata pendleburyi Betrem & Bradley 1964, syn. nov., Regiscolia maculata (Drury, 1773) = Triscolia maculata barbara Micha, 1927, syn. nov. = Triscolia maculata form verticalis Micha, 1927, syn. nov. = Triscolia maculata sicula Micha, 1927, syn. nov. = Scolia (Triscolia) maculata flavifrons var. funerea Guiglia, 1928, syn. nov. = Scolia (Triscolia) flavifrons var. nigra Dusmet, 1930, syn. nov. = Megascolia (Regiscolia) flavifrons form vespertina Nagy, 1967, syn. nov. = Megascolia (Regiscolia) flavifrons form vernalis Nagy, 1967, syn. nov. All valid species are redescribed, the female of R. almoraensis is described for the first time and the female of R. splendida is diagnosed for the first time. The genus Megascolia now consists of three species, Regiscolia stat. nov. of nine species and Gigascolia gen. nov. of two species. The status and validity of some taxa is discussed. Illustrated keys to genera, species and valid subspecies are provided, as well as illustrations and distribution maps for all species.