A remarkable diversity of parasitoid beetles (Ripiphoridae) in Cretaceous amber, with a summary of the Mesozoic record of Tenebrionoidea

A diversity of new wedge-shaped beetles (Coleoptera: Ripiphoridae) are described and figured from Burmese amber, representing three new genera and five new species in two subfamilies - Ripidiinae and Pelecotominae. Amberocula gen. nov., is the third genus of Ripidiini documented from the Upper Cretaceous (lowermost Cenomanian) amber of northern Myanmar. Three species are included in the genus: Amberocula muelleri sp. nov. (type species), A. costata sp. nov., and A. fallax sp. nov. Amberocula is represented by six single male inclusions and one quadruple male syninclusion (for A. muelleri). The genus is distinguishable by the combination of number and shape of antennomeres and tarsomeres, reduced mouthparts, and shape of the head, compound eyes, and thorax relative to all extant and fossil members of the tribe Ripidiini. In addition, three single male inclusions and one syninclusion of six males indistinguishable from Paleoripiphorus deploegi Perrichot, Nel, and Neraudeau (Ripidiini) are reported. Described syninclusions of both genera support the previous assumption of aggregative-like behavior of male Ripidiini may be a groundplan feature of the tribe and responsible for the presence of such syninclusions. Two monotypic genera, Plesiotoma alissae gen. et sp. nov. and Burmitoma nalae gen. et sp. nov., are representative of the subfamily Pelecotominae and are also described and figured. The inclusions represent the second and third definitive records for the subfamily in Cretaceous amber, and also the discovery of fossil pelecotomine females. They differ from the contemporaneous Flabellotoma Batelka, Prokop and Engel in the presence of more complete tibial spur formulas and the absence of a ventral abdominal microsclerite. The presence of three species of Amberocula, additional material of P. deploegi, and two new genera of Pelecotominae demonstrates a surprising abundance of ripiphorids in Cretaceous amber, and we provide comments on the past diversity of this parasitoid family during the period, as well as observations on the nature of their preservation and paleoethology. The known diversity of Mesozoic Tenebrionoidea is cataloged and a key to the Cretaceous diversity of Ripiphoridae is presented. (C) 2018 Elsevier Ltd. All rights reserved.