Life, the universe, and Ophion: systematics and diversity of a little-known ichneumonid genus
Citation
Schwarzfeld, M.D. Sperling, F.A.H. 2016. Life, the universe, and Ophion: systematics and diversity of a little-known ichneumonid genus. Symposium: Evolution of a megadiverse group: the ichneumonoid wasps (Hymenoptera: Braconidae, Ichneumonidae). International Congress of Entomology, Sep. 25-30, Orlando, FL.
Résumé en langage clair
The genus Ophion is a widespread and common genus of parasitic wasps. However the group was almost entirely unknown taxonomically. This research used molecular data to construct the first phylogeny of the genus, and to assess its species diversity. The genus can now be divided into thirteen species-groups, and the diversity was unexpectedly high, even within regions (e.g. the western Palearctic) where Ophion have been better studied.
Résumé
Introduction
Ophion is a commonly collected nocturnal genus of Ichneumonidae that is most diverse in temperate regions. Within the genus, a few species-groups had been proposed; however, the vast majority of species (and virtually all of the Nearctic species) were lumped into a single, presumably paraphyletic species-group, the Ophion luteus species-group. The Nearctic diversity within this group was estimated at around 50 species, mostly undescribed. All previous hypotheses regarding phylogeny or diversity within the genus were based on morphology; prior to this work, Ophion had not been examined with molecular data.
Methods
Nearctic and western Palearctic species were sequenced for three genetic markers (COI, ITS2, and 28S). A phylogeny was constructed using parsimony and likelihood methods. The species diversity was assessed using several automated species delimitation methods under a range of parameters, based on COI and ITS2 data.
Results/Discussion
Based on the molecular phylogeny, Ophion from this study can be divided into thirteen species groups, with a few individuals remaining unassociated. Most of these species-groups are monophyletic lineages within the former O. luteus s.l. species-group. A single clade included all species except for three, which were more strongly associated with other genera within the Ophion genus-group. There were wide discrepancies between the various species delimitation methods in terms of total number of species; however they all agreed that species diversity in Ophion is very high. The Nearctic diversity is likely twice the estimated morphology-based diversity, and even among the relatively well-known British fauna, there are several undescribed species.