Phylogeny of the platygastroid wasps (Hymenoptera) based on sequences from the 18S rRNA, 28S rRNA and cytochrome oxidase I genes: implications for the evolution of the ovipositor system and host relationships

Abstract

The Platygastroidea are a diverse group of mostly small to tiny wasps, the common biology for which is endoparasitism of insect and spider eggs. No analytically-based phylogeny exists for the superfamily, and the current suprageneric classification is flawed in part because of its reliance on homoplasious and pleisiomorphic morphological characters. To determine platygastroid relationships as a basis for investigating host and ovipositor evolution, phylogenies of > 70 in-group species (representing 55 genera) were reconstructed by parsimony and Bayesian methods using three molecular markers; the mitochondrial cytochrome oxidase I and the nuclear genes 28S and 18S rRNA . The results strongly support the monophyly of the superfamily and one of the two families, Platygastridae, but the Scelionidae are most likely polyphyletic. However, within the Scelionidae, there is a well supported 'main scelionid clade' that contains the majority of genera assigned to the family. At the subfamilial level, both putative subfamilies of Platygastridae, the Platygastrinae, and Sceliotrachelinae, are likely to be polyphyletic. Within the Scelionidae, both the Teleasinae and Telenominae are monophyletic, but the Scelioninae is clearly not so. The current tribal classification for the Scelionidae is in need of major reassessment because no tribes, with the exception of the Scelionini s.s ., were found to be monophyletic. Further illustrating the problems associated with the current classification is the nonmonophyly of a number of genera, namely Opisthacantha Caloteleia , Telenomus , Trimorus , Teleas and Idris. Analysis of ovipositor evolution in the superfamily revealed that the Ceratobaeus -type ovipositor system is ancestral; however, this trait was lost prior to the evolution of the main scelionid clade, for which the Scelio -type ovipositor system is ancestral and defines a mostly paraphyletic assemblage. Ancestral state analysis indicates that the Ceratobaeus -type ovipositor was subsequently re-evolved in the main scelionid clade, representing a possible contradiction of Dollo's law. Previously, the tribal placement has been used to predict the host associations of genera for which host data were unavailable. However, the fact that most tribes are not monophyletic throws into doubt any such speculation based on the current classification.

Systematics and biology of the aberrant intertidal parasitoid wasp Echthrodesis lamorali Masner (Hymenoptera : Platygastridae s.l.): a parasitoid of spider eggs

“…In analysis 1, sequence data for the CO1 and 28S rDNA genes were employed for a comprehensive sampling of 22 species (representing seven genera and including E. lamorali) of platygastroids known to parasitise spider eggs, plus an additional 10 playgastroid species representing 10 genera associated with a range of insect hosts (Table 1). Of the 22 species that parasitise spider eggs, nine were newly sequenced while the remaining came from either Carey et al (2006) or Murphy et al (2007) (Table 1). Two platygastrids, Piestopleura sp.…”

“…Two platygastrids, Piestopleura sp. and Synopeas sp., were used as outgroups based on the results of Murphy et al (2007).…”

“…To further test the relationships of Echthrodesis, the Bayesian analysis presented in Murphy et al (2007) was repeated with sequences of Echthrodesis added to the dataset (Analysis 2). This analysis employed sequence data for three genes (CO1, 28S rDNA, 18S rDNA; see below for details) and had the advantage of placing Echthrodesis among a far greater sampling of taxa across the whole superfamily (86 species representing 59 genera).…”

“…Somewhat surprisingly, recent molecular phylogenetic appraisals of platygastroid genera using multiple genes (Carey et al 2006;Murphy et al 2007) have revealed the spider egg parasitoids (i.e. Baeini) to be polyphyletic, with Baeus, Ceratobaeus Ashmead, Hickmanella Austin, Idris Foerster and Odontacolus Kieffer forming a monophyletic group, and Mirobaeoides and Neobaeus together forming an independent clade that is sister to Embidobia.…”

The maxillo-labial complex of Sparasion (Hymenoptera, Platygastroidea)

“…These wasps are widespread in Eurasia, Africa, and temperate North America (Johnson et al 2008), and, as far as is known, these species are egg-parasitoids of Tettigoniinae (Orthoptera: Tettigoniidae) (Johnson et al 2008). Based on the latest phylogenetic analyses, Sparasion is part of a small lineage that is sister to either the vast majority of Scelionidae sensu Haliday 1839 (Murphy et al 2007) or Platygastridae sensu stricto (Austin and Field 1997). Species in this lineage typically exhibit ancestral morphological states (Murphy et al 2007, Austin andField 1997), which should facilitate homologization of mouthparts with other hymenopterans.…”