A new Late Cretaceous family of Hymenoptera, and phylogeny of the Plumariidae and Chrysidoidea (Aculeata)

Denis Brothers

doi:10.3897/zookeys.130.1591

Abstract

The taxonomic placement of an enigmatic species of wasp known from two specimens in Late Cretaceous New Jersey amber is investigated through cladistic analyses of 90 morphological characters for 33 terminals ranging across non-Aculeata, non-Chrysidoidea, most subfamilies of Chrysidoidea and all genera of Plumariidae (the family to which the fossils were initially assigned), based on use of exemplars. The fossil taxon is apparently basal in Chrysidoidea, most likely sister to Plumariidae, but perhaps sister to the remaining chrysidoids, or even sister to Chrysidoidea as a whole. It is described as representing a new family, Plumalexiidae fam. n., containing a single species, Plumalexius rasnitsyni gen. et sp. n. Previous estimates of relationships for the genera of Plumariidae and for the higher taxa of Chrysidoidea are mostly confirmed. The importance of outgroup choice, and additivity and weighting of characters are demonstrated.

Highlights

The phylogeny of the Hymenoptera, and the Aculeata, has recently been investigated critically by several authors
The two amber pieces (Figures 3–4), each embedded in epoxy as described by Nascimbene and Silverstein (2000), were studied using standard methods and illustrated using stacked photographs taken with a Canon Powershot G10 digital camera adapted to Wild M7 and Wild M11 microscopes using a Clearshot 600 adapter kit (Alexis Scientific) and combined with CombineZP software (Hadley 2010)
Some character states were not absolutely clear, but the most-probable states inferred are those used in the analyses; if such states could not be inferred they are coded as unknown

Summary

Introduction

The phylogeny of the Hymenoptera, and the Aculeata, has recently been investigated critically by several authors The consensus tree from the “ weighted additive” analysis (Figure 14) shows Chrysidoidea as monophyletic, all chrysidoid families as monophyletic ( with their relationships often not convincingly resolved, as shown by several apparent clades having no or very low relative resampling support), Plumalexius sister to Plumariidae (this clade sister to the remaining chrysidoids), and the plumariid genera with similar relationships to those found earlier (see Figure 2).

Results

Conclusion