DOI: 10.15468/qq62ks
title: Notes on rhopalosomatid wasps of Dominican and Mexican amber (Hymenoptera: Rhopalosomatidae) with a description of the first fossil species of Rhopalosoma Cresson, 1865

description: This dataset contains the digitized treatments in Plazi based on the original journal article Lohrmann, Volker, Ohl, Michael, Michalik, Peter, Pitts, James P., Jeanneau, Laurent, Perrichot, Vincent (2019): Notes on rhopalosomatid wasps of Dominican and Mexican amber (Hymenoptera: Rhopalosomatidae) with a description of the first fossil species of Rhopalosoma Cresson, 1865. Fossil Record 22 (1): 31-44, DOI: 10.5194/fr-22-31-2019, URL: http://dx.doi.org/10.5194/fr-22-31-2019Abstract. Rhopalosomatidae are a family of aculeate wasps that are ectoparasitoids of crickets as larvae and are predominantly distributed pantropically. The published fossil record of the family is scarce. Here, we report three new fossil rhopalosomatid wasp specimens from Dominican and Mexican amber. Rhopalosoma hispaniola Lohrmann sp. nov. is described and documented from Dominican amber by two separate inclusions – one of each sex. An additional fossil female Rhopalosoma is described and documented from Mexican amber but is not named due to the insufficient preservation of the fossil. The new fossils, which are morphologically intermediate between Townes’ isopus and poeyi species groups, do not only represent the first fossil records of an extant genus of this peculiar family but also the first records of the family in Dominican and Mexican amber.1 IntroductionThe Recent New World fauna of Rhopalosomatidae is currently comprised of 35 formally described species assigned to three genera: Liosphex Townes, 1977, with 13 species, Olixon Cameron, 1887, with 5 species, and Rhopalosoma Cresson, 1865, with 17 species (Townes, 1977; Lohrmann and Ohl, 2010; Lohrmann et al., 2012). Their distribution ranges from southeastern Canada and the northeastern USA to northern Argentina and southern Brazil, with the vast majority occurring in the tropic zone. As far as it is known, female rhopalosomatids hunt for crickets (Orthoptera) that ultimately serve as hosts for their ectoparasitoid larvae (Perkins, 1908; Hood, 1913; Gurney, 1953; Lohrmann et al., 2014; Blaschke et al., unpublished results; see also Fig. 1a–b).The recent discovery of an ectoparasitoid rhopalosomatid wasp larva attached to its cricket host in mid-Cretaceous Burmese amber revealed a remarkable constancy of the biology of Rhopalosomatidae over the last 100 million years (Lohrmann and Engel, 2017). In some way, this extraordinary fossil hides the fact that we still know little about the origin and evolution of this peculiar family of aculeate wasps. Two of the four fossil taxa previously assigned to the family, Mesorhopalosoma Darling (in Darling and Sharkey, 1990) and Paleorhopalosoma Nel et al., 2010, have been transferred to the sphecoid wasps (Osten, 2007; Archibald et al., 2018). Additionally, Propalosoma Dlussky and Rasnitsyn, 1999, has been transferred to the myrmeciine ants (Archibald et al., 2018). This leaves Eorhopalosoma Engel, 2008, which is another Cretaceous Burmese amber fossil, as the sole fossil species in the family so far.No Rhopalosomatidae have been recorded from Dominican and/or Mexican amber, even though many of the extant aculeate families currently distributed in the neotropics are already reported from either of these contemporary outcrops. For Dominican amber, these include Andrenidae, Apidae, Bethylidae, Chrysididae, Crabronidae, Colletidae, Dryinidae, Formicidae, Halictidae, Megachilidae, Mutillidae, Pompilidae, Sclerogibbidae, Scolebythidae, and Vespidae (Penney, 2010; Rodriguez et al., 2016). For Mexican amber, these include Apidae, Bethylidae, Dryinidae, and Formicidae (Solórzano Kraemer, 2010).Figure 1. Rhopalosomatidae spp. (a–b) Recent rhopalosomatid larva (last instar, shortly before leaving the host, putatively Rhopalosoma nearcticum Brues) parasitizing a hapithine cricket (Grylloidea). Photographed at Jones Nature Preserve, Rappahannock County, Virginia, USA, on 15 September 2017. Photos: Judy Gallagher, CC-BY-2.0, originally posted to Flickr. (c–d) Rhopalosoma nearcticum Brues, male. (c) Photographed in Mobile (Dog River), Mobile County, Alabama, USA, on 4 July 2011. Photo: Robert Lord Zimlich, originally posted to BugGuide. (d) Penis valve in lateral view. Abbreviations: ant – anterior, hpv – head of penis valve, pap1 – first preapical process, pap2 – second preapical process, pap3 – third preapical process, and pos – posterior.Due to their general appearance, members of the rhopalosomatid wasp genus Rhopalosoma (see Fig. 1c), as well as the Old World Paniscomima Townes, 1977, are often mistaken for nocturnal ichneumonids, e.g., Ophion spp. or Netelia spp. (McGown, 1998), and one is strongly encouraged to go through collections of unidentified subtropical or tropical nocturnal ichneumonids when searching for material of the genus. This is also true for the fossil record. During our surveys of fossil inclusions, three adult rhopalosomatid wasps have been discovered in Dominican and Mexican amber, and one of the fossils described herein was indeed initially identified and advertised as a “Large Ichneumonid Wasp”.All three of the new fossils belong to the Recent genus Rhopalosoma. The aim of the present study is to describe and illustrate these fossils, which are not only the first fossil records of the genus but are also the first of the family from Dominican and Mexican amber and from the Miocene as a whole.