&amp;lt;i&amp;gt;†&amp;lt;/i&amp;gt;&amp;lt;i&amp;gt;Cretolixon&amp;lt;/i&amp;gt; – a remarkable new genus of rhopalosomatid wasps (Hymenoptera: Vespoidea: Rhopalosomatidae) from chemically tested, mid-Cretaceous Burmese (Kachin) amber supports the monophyly of Rhopalosomatinae

Qi Zhang,Peter Michalik,Vincent Perrichot,Patrick Müller,Laurent Jeanneau,Jeremy Blaschke,Volker Lohrmann

doi:10.5194/fr-23-215-2020

Abstract

Abstract. Rhopalosomatidae, currently considered the sister group of the Vespidae, are an enigmatic family of aculeate wasps that originated in the Late Jurassic or Early Cretaceous. Despite their considerable age, very few fossils of the family have been reported – all of them in amber (Miocene Dominican, Miocene Mexican, and mid-Cretaceous Burmese ambers). Here we report a new mid-Cretaceous rhopalosomatid wasp, Cretolixon alatum Lohrmann, gen. et sp. nov., from Burmese (Kachin) amber. This new genus has a unique mixture of characters, some of which are only known from the recent brachypterous genus Olixon and others of which are known only from the recent macropterous genera. Thus, Cretolixon Lohrmann, gen. nov. not only provides further evidence for the monophyly of the family but also contributes evidence for the monophyly of the Rhopalosomatinae. Key characters of the family are discussed, and an updated checklist of the world genera and fossil species and occurrences of Rhopalosomatidae is provided. Additionally, a chemical analysis was performed for three of the newly reported fossils as well as for the amber piece containing the rhopalosomatid larva described by Lohrmann and Engel (2017) to ascertain their amber vs. copal nature and their affinities with each other and previously described Burmese amber.

Highlights

Rhopalosomatidae, currently considered the sister group of the well-known Vespidae (Pilgrim et al, 2008; Branstetter et al, 2017), are an enigmatic family of aculeate wasps that originated in the Late Jurassic (Brady et al, 2009) or Early Cretaceous (Wilson et al, 2013; Branstetter et al, 2017)
The total ion chromatograms of the thermochemolysis–gas chromatography–mass spectrometry (THM–GC–MS) analysis of the Burmese resins are illustrated in Figs. 1 and B2
The retention times of the methyl esters of C15 labdanoids were similar in Burmese ambers and in the reference Baltic amber, which indicated that these acids were derived from polymerized communic acid and a regular configuration of labdanoid diterpenes, typical of class Ia and Ib ambers (Fig. 2)

Summary

Introduction

Rhopalosomatidae, currently considered the sister group of the well-known Vespidae (Pilgrim et al, 2008; Branstetter et al, 2017), are an enigmatic family of aculeate wasps that originated in the Late Jurassic (Brady et al, 2009) or Early Cretaceous (Wilson et al, 2013; Branstetter et al, 2017). Notwithstanding their geological age or the species diversity of their putative sister, Rhopalosomatidae are a speciespoor family, currently comprising less than a hundred recent species assigned to four genera (Aguiar et al, 2013). Lohrmann et al.: †Cretolixon – a remarkable new genus of rhopalosomatid wasps of crickets (e.g., Perkins, 1908; Hood, 1913; Gurney, 1953; Lohrmann et al, 2014; Miller et al, 2019) – a habit that has seemingly remained unchanged since the mid-Cretaceous (Lohrmann and Engel, 2017)

Methods

Results

Discussion

Conclusion