Apoid wasps (Hymenoptera: Apoidea) from mid-Cretaceous amber of northern Myanmar

In the present study we describe two new families, two new subfamilies, three new tribes, two new subtribes, 14 new genera and 16 new species. The following new taxa are proposed: †Allommationidae fam. nov., having †Allommation gen. nov. as type genus and containing three new species, †A. procerum sp. nov., †A. elongatum sp. nov. and †A. grande sp. nov.; †Cretastatini trib. nov., in Astatinae, containing †Cretastatus longevus gen. nov. et sp. nov.; †Ammosphecium diabolicum gen. nov. et sp. nov., placed in Eremiaspheciini; †Megaroliini trib. nov., in Bembicinae, containing †Megarolium paradoxum gen. nov. et sp. nov.; †Pristinopterini trib. nov., also in Bembicinae, for †Pristinopterus spectabilis gen. nov. et sp. nov.; †Odontosericina subtrib. nov., in Psenini, to accommodate †Odontosericus burmensis gen. nov. et sp. nov.; †Helosericina subtrib. nov., also in Psenini, for †Helosericus verrucosus gen. nov. et sp. nov.; †Pristopsen obscurus gen. nov. et sp. nov., placed in Psenina, Psenini; and †Spheciellidae fam. nov., containing †Spheciellus aenigmaticus gen. nov. et sp. nov. In addition, we recognize the family †Cirrosphecidae Antropov, new status, as an intermediate group between the apoid wasps and the bees; we redescribe the male of †Cirrosphex mirabilis Antropov and describe its female for the first time; two subfamilies are recognized in †Cirrosphecidae: †Cirrosphecinae for †Cirrosphex and †Haptodioctes apiformis gen. nov. et sp. nov., and †Glenocephalinae subfam. nov. for †Glenocephalus mandibularis gen. nov. et sp. nov. We transfer †Apodolichurus Antropov to Heterogynaidae as a subfamily, †Apodolichurinae Antropov, new status; we also propose †Ptilocosminae subfam. nov. in Heterogynaidae, with the following new taxa: †Ptilocosmus corniculatus gen. nov. et sp. nov., †Thigmocosmus longicornis gen. nov. et sp. nov. and †Aulacicosmus setosus gen. nov. et sp. nov. Additionally, we transfer †Discoscapa Poinar to Crabroninae, as a tribe †Discoscapini Poinar, new status; and †Melittosphex Poinar and Danforth, a group possibly related to the sapygid-mutillid clade, is removed from Apoidea and left as incertae sedis in Aculeata. The heterogeneous composition of the Apoidea fauna found in Burmese amber, with groups associated with tropical wet forests as well as taxa belonging to groups having association with dry temperate regions, is discussed. We invoke a complex landscape, with a mosaic of vegetation types and more dynamic environmental conditions, with fr