Scott R. Shaw

Euphorine phylogeny: the evolution of diversity in host-utilization by parasitoid wasps (Hymenoptera: Braconidae)

ABSTRACT. 1 New data on the phylogeny of the braconid subfamily Euphorinae supports the hypothesis that parasitism of adult insects by Euphorinae originated during parasitism of Chrysomelidae, a group whose larvae are ecologically coincident with adults. 2 Evolution of the habit of attacking the adult stage opened a new adaptive zone; subsequently the Euphorinae have diversified on to a phylogenetically greater variety of hosts than any other braconid subfamily. 3 Parasitism of eumastacid grasshoppers evolved from beetle parasitism in the tribe Perilitini. 4 The tribe Euphorini shows the greatest diversity of hosts utilized. Most attack Heteroptera; however, Chrysopopthorus diversified on to adult Chrysopidae, Euphoriella on to Psocoptera, and Cryptoxilos on to Scolytidae. 5 Parasitism of bark beetles (Scolytidae) has evolved independently in three genera: Cosmophorus, Cryptoxilos and Ropalophorus. This is the most specialized form of beetle parasitism by euphorines, since it involves direct parasitism of concealed hosts. 6 Parasitism of adult hymenopterans by the tribe Syntretini may be related to attacking hosts while they are foraging at flowers. 7 The pattern of diversification in the Euphorinae indicates several adaptive radiations within host orders, as well as a history of major host‐shifts between phylogenetically distantly‐related host groups: Coleoptera to Orthoptera; Coleoptera to Hymenoptera; Coleoptera to Heteroptera; Heteroptera to Neuroptera, Psocoptera, and back to Coleoptera. Both the‘host taxonomy’and‘host habitat’hypotheses of host‐shifting are supported. Host‐shifts have involved hosts occurring in the same micro‐habitat and usually having similar feeding habits. This is consistent with current theory of host‐location by means of host‐produced kairomones and visual cues.

DIFFERENTIAL PARASITISM OF MACROLEPIDOPTERAN HERBIVORES ON TWO DECIDUOUS TREE SPECIES

Patterns of larval parasitism among species in the macrolepidopteran assem- blages on two riparian tree species, Acer negundo L. (box elder) and Salix nigra (Marsh) (black willow) were examined. Larvae were collected throughout the growing season for five years and reared for parasitoid emergence. Total parasitism of larvae on box elder was significantly higher than that of larvae on black willow. Comparisons of parasitism levels among lepidopteran families showed that in five of seven families larval parasitism on box elder was significantly higher than on black willow. For species whose larvae were found on both tree species, total parasitism was significantly higher when the larvae were on box elder than when larvae of the same species were on black willow. In comparisons of species found on both tree species, larvae in three of seven families suffered significantly higher levels of parasitism when on box elder than when on black willow. The roles of the functional/numerical responses of parasitoids, common and numerically dominant parasitoid species, and plant volatiles are considered as causal mechanisms underlying differential parasitism but are not supported by the data.

PHYLOGENY OF THE SUBFAMILIES OF THE FAMILY BRACONIDAE (HYMENOPTERA: ICHNEUMONOIDEA): A REASSESSMENT

Abstract— The recently published phylogeny of Braconidae by Quicke and van Achterberg is reassessed. Character‐state definitions and character polarities are evaluated, and more rigorous methods are suggested. Our results indicate that there are many more parsimonious solutions to their data set, the consensus of which differs substantially from their results. Based on our reassessment, little can be said about the relationships among braconid subfamilies. Consensus trees show the cyclostomes as a largely unresolved basal grade. The two other major lineages which have been proposed, the helconoids and microgastroids, are somewhat better resolved, but not consistently so. Relationships among the helconoids vary considerably depending on the parameters used for parsimony analysis.

Utility of the DNA barcoding gene fragment for parasitic wasp phylogeny (Hymenoptera: Ichneumonoidea): data release and new measure of taxonomic congruence

The enormous cytochrome oxidase subunit I (COI) sequence database being assembled from the various DNA barcoding projects as well as from independent phylogenetic studies constitutes an almost unprecedented amount of data for molecular systematics, in addition to its role in species identification and discovery. As part of a study of the potential of this gene fragment to improve the accuracy of phylogenetic reconstructions, and in particular, exploring the effects of dense taxon sampling, we have assembled a data set for the hyperdiverse, cosmopolitan parasitic wasp superfamily Ichneumonoidea, including the release of 1793 unpublished sequences. Of approximately 84 currently recognized Ichneumonoidea subfamilies, 2500 genera and 41 000 described species, barcoding 5′‐COI data were assembled for 4168 putative species‐level terminals (many undescribed), representing 671 genera and all but ten of the currently recognized subfamilies. After the removal of identical and near‐identical sequences, the 4174 initial sequences were reduced to 3278. We show that when subjected to phylogenetic analysis using both maximum likelihood and parsimony, there is a broad correlation between taxonomic congruence and number of included sequences. We additionally present a new measure of taxonomic congruence based upon the Simpson diversity index, the Simpson dominance index, which gives greater weight to morphologically recognized taxonomic groups (subfamilies) recovered with most representatives in one or a few contiguous groups or subclusters.

Phylogeny and biogeography of the parasitoid wasp family Megalyridae (Hymenoptera)

A phylogenetic analysis of the eight extant and three extinct fossil genera of Megalyridae was conducted based on twenty external morphological characters. A minimum length cladogram for the eight extant genera is resolved: Rigel+(Megalyridea+{ [Megalyra+( Cryptalyra + Carminator)] + [Neodinapsis + (Dinapsis +Ettchellsia)] 1). One equally parsimonious alternative, differing only by the possibly more basal position of Megalyra, is outlined; however, the biogeographical interpretation is similar, in either case. The biogeography of megalyrid genera is discussed in terms of these putative relationships; the relationships and distributions of the six most apical clades are explained in terms of the distribution of continental land masses during the upper Cretaceous, 90 mya. South America, South Africa, and the Malay Archipelago are evaluated as possible composite areas. Current megalyrid distributions in the Malay Archipelago are reviewed relative to geological and climatological events since the Miocene. Addition of fossil genera resulted in six equally parsimonious cladograms because of missing data. These are summarized as a strict consensus tree: Rigel + (Megalyridea + [Megalyra + ( Prodinapsis + Cretodinapsis + (Cryptalyra + Carminator) + (Neodinapsis + [Maimetsha + (Dinapsis + Ettchellsial])}]). Although less resolved, this tree corresponds closely to the cladogram based on extant general alone; furthermore, the addition of fossils establishes the Cretaceous age of the dinapsine lineage. The family Megalyridae is postulated to have originated on Pangaea, possibly as early as the late Triassic. A revised tribal classification for the megalyrids is proposed.

Carminator, a new genus of Megalyridae (Hymenoptera) from the Oriental and Australian regions, with a commentary on the definition of the family

The taxonomic history of the family Megalyridae is reviewed. Carminator gen.n. from the Oriental and Australian regions is described and illustrated. Four new species are included in the genus: C.affinis, Cater, C.cavus and C.nooni. A key to the species is provided.

Past and present diversity and distribution in the parasitic wasp family Megalyridae (Hymenoptera)

The phylogenetic relationships of extant and extinct Megalyridae are analysed at the genus level. The dataset comprises seven outgroup taxa, all eight extant genera and a number of extinct taxa that have been associated with Megalyridae, including two genera from Maimetshidae, whose affinity with Megalyridae is uncertain. Analytical results are unstable because some of the fossil taxa have many missing entries. The most stable results are produced when the maimetshid taxa and Cretodinapsis are excluded. When included, these taxa fall outside crown‐group Megalyridae, the maimetshid taxa being the sister of Orthogonalys (Trigonalidae). Based on the results of our analyses, we synonymize the fossil genera Rubes Perrichot n.syn. and Ukrainosa Perrichot & Perkovsky n.syn. with Prodinapsis, creating the new combinations Prodinapsis bruesin.comb. and Prodinapsis prolatan.comb. When comparing past and present distributions of Megalyridae with the results of the phylogenetic analyses, it is evident that the genera radiated in the Mesozoic, and that the family as a whole was much more widespread then. The present‐day distribution is essentially relictual, with range contraction since the early Tertiary probably being the result of climate deterioration, which caused the disappearance of tropical forests throughout the Palaearctic.

A phytophagous braconid, Allorhogas conostegia sp. nov. (Hymenoptera: Braconidae), in the fruits of Conostegia xalapensis (Bonpl.) D. Don (Melastomataceae)

Before 1989 all braconid wasps were thought to be parasitoids, but in that year the first phytophagous species was reported. Subsequently, a few other examples of phytophagy have been discovered, most of which are species of Allorhogas in the subfamily Doryctinae. Until now, all demonstrated examples of phytophagy in this genus have been as gall inducers in the fruits of Fabaceae. Here we describe a new species from Costa Rica, Allorhogas conostegia Marsh and Shaw, and provide evidence that it forms galls in the fruits of Conostegia xalapensis (Melastomataceae). We also provide information on the phenology of the plant and of the galls and the effects of the galls on the host plant, and we discuss the potential species richness of Allorhogas in the Neotropics.

Systematics and evolution of gall formation in the plant‐associated genera of the wasp subfamily Doryctinae (Hymenoptera: Braconidae)

Gall formation is a specialised form of phytophagy that consists of abnormal growth of host plant tissue induced by other organisms, principally insects and mites. In the mainly parasitoid wasp subfamily Doryctinae, gall association, represented by gall inducers, inquilines and their parasitoids, is known for species of seven genera. Previous molecular studies recovered few species of six of these genera as monophyletic despite their disparate morphologies. Here, we reconstructed the evolutionary relationships among 47 species belonging to six gall‐associated doryctine genera based on two mitochondrial and two nuclear gene markers. Most of the Bayesian analyses, performed with different levels of incomplete taxa and characters, supported the monophyly of gall‐associated doryctines, with Heterospilus (Heterospilini) as sister group. Percnobracon Kieffer and Jörgensen and Monitoriella Hedqvist were consistently recovered as monophyletic, and the validity of the monotypic Mononeuron was confirmed with respect to Allorhogas Gahan. A nonmonophyletic Allorhogas was recovered, although without significant support. The relationships obtained and the gathered morphological and biological information led us to erect three new genera originally assigned to Psenobolus: Ficobolus gen.n. (F. paniaguai sp.n. and F. jaliscoi sp.n.), Plesiopsenobolus gen.n. (Pl. mesoamericanus sp.n., Pl. plesiomorphus van Achterberg and Marsh comb.n., and Pl. tico sp.n.), and Sabinita gen.n. (S. mexicana sp.n.). The origin of the gall‐associated doryctine clade was estimated to have occurred during the middle Miocene to early Oligocene, 16.33–30.55 Ma. Our results support the origin of true gall induction in the Doryctinae from parasitoidism of other gall‐forming insects. Moreover, adaptations to attack different gall‐forming taxa on various unrelated plant families probably triggered species diversification in the main Allorhogas clade and may also have promoted the independent origin of gall formation on at least three plant groups. Species diversification in the remaining doryctine taxa was probably a result of host shifts within a particular plant taxon and shifts to different plant organs.

Ononis, a new genus from Central America, with an analysis of its phylogenetic placement in the tribe Euphorini (Hymenoptera: Braconidae)

ABSTRACT. A phylogenetic analysis of the genera of the euphorine braconid tribes Perilitini, Dinocampini and Euphorini was conducted to determine the correct placement of the eximius Muesebeck species‐group, which has formerly been placed in Perilitus Nees. Results indicate that the eximius‐gxoxvp cannot be validly assigned to Perilitus, rather, it should be assigned to a new genus in the tribe Euphorini. Ononis gen.n. is described to include O.eximius (Muesebeck) comb.n. and O.masoni sp.n.