Systematics and biogeography of Australian rhopalosomatid wasps (Hymenoptera: Rhopalosomatidae) with a global synopsis of the enigmatic genusOlixonCameron

Abstract

The wasp family Rhopalosomatidae is represented in Australia only by the genus Olixon Cameron. Species of this genus have previously been considered rare based on material in collections and have rarely been observed in the field. All known species of Olixon are brachypterous, solitary ectoparasitoids of crickets (Orthoptera: Gryllidae). Prior to our study the world fauna comprised 11 species of which two were endemic to north‐eastern Australia. Based on specimens collected during recent intensive surveys in Australia we record 17 species for the continent. Fifteen of these species are described as new, which more than doubles the world fauna of Olixon: Olixon abrahami, O. danggari, O. ferrugineum, O. guyim, O. harveyi, O. helgae, O. jandakotae, O. jawoyn, O. jenningsi, O. kakadui, O. pilbara, O. wajuk, O. waldockae, O. wuthathi and O. zonalespp.n. Females of Olixon australiae Perkins and Olixon flavibase Townes are redescribed, and the male of O. flavibase is described for the first time. A key is provided for all 17 Australian species and their distribution is discussed. Results of a cladistic analysis of the world species of Olixon based on 41 morphological characters for 24 ingroup species are presented. The results obtained from equal and implied weighting parsimony analyses indicate that: (i) the Australian species of Olixon are not monophyletic, (ii) about three‐quarters of the Australian species form a monophyletic group, and (iii) a Central/South American Olixon is sister to all other species. The implications of these results for the biogeography of world Olixon species are briefly discussed.

DNA barcoding of rhopalosomatid larvae reveals a new host record and genetic evidence of a second species of Rhopalosoma Cresson (Hymenoptera, Rhopalosomatidae) in America north of Mexico

“…Although a species-level identification key for Rhopalosoma exists (Townes 1977), accurate identification remains a challenge. Other genera within Rhopalosomatidae (i.e., Liosphex, Olixon and Paniscomima) have received major taxonomic updates since Townes' family revision in 1977 and many new species have been discovered (e.g., Guidotti 2007;Krogmann et al 2009;Lohrmann and Ohl 2010;Lohrmann 2011;Lohrmann et al 2012). Rhopalosoma, however, has remained almost untouched apart from minor, mostly faunistic notes (e.g., Freytag 1984;Coronado Blanco and Cancino 2002;Smith 2008) with the exception of the description of the first fossil species in the genus (Lohrmann et al 2019).…”

“…Morphological phylogenies have been reconstructed for the closely related Paniscomima Enderlein (Guidotti 2007), the brachypterous Olixon Cameron (Krogmann et al 2009), and the family as a whole (Guidotti 1999). However, no comprehensive molecular study has focused on the Rhopalosomatidae itself, nor thoroughly examined any individual genus within it.…”

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

“…Rhopalosomatidae Ashmead: Brues, 1922: 102 (and most subsequent authors). Krogmann et al, 2009) Among aculeate Hymenoptera, Rhopalosomatidae can be easily identified by the following combination of characters: basal flagellomeres with distinct apical bristle(s) (Figs. 3a, d, 4d, 5b, 6c-e; very small or completely reduced in many Olixon), mesosternum with posterad paired lobes covering the bases of the mesocoxae (Figs.…”

Review of the hymenopteran fauna of New Caledonia with a checklist of species

“…In Australia, this small family is known from 17 described species that belong to the antlike, wing-reduced genus Olixon (Krogmann et al 2009). These species are distributed throughout the Australian continent, including arid and semi-arid and wet tropical habitats (Krogmann et al 2009). This genus may also occur in New Guinea but the family is absent from New Zealand and New Caledonia.…”

“…This genus may also occur in New Guinea but the family is absent from New Zealand and New Caledonia. Although no host records are known from Australia, members of this family are all thought to be ectoparasitoids of crickets (Orthoptera: Gryllidae) (Townes 1977a;Krogmann et al 2009).…”