Search for: All records

Abstract Ants (Hymenoptera: Formicidae) have great potential to exert influence over the morphological evolution of their obligate mutualist partners. Obligately myrmecophilic mealybugs are noted for their unusual morphology, and while this is often attributed to their relationship with ants, a quantitative assessment of this link is lacking. We address this need by evaluating morphological change among mealybugs as a function of ant association. This study considers the associates of 2 independent ant clades—Acropyga Roger, 1862 ants associated with root mealybugs from the families Xenococcidae and Rhizoecidae and herdsmen ants from the Dolichoderus cuspidatus (Smith, F., 1857) species-group associated with mealybugs from the tribe Allomyrmococcini (Pseudococcidae)—and compares them to free-living or potentially myrmecophilic species sampled from among the mealybugs and root mealybugs. We use a combination of geometric morphometric and linear datasets to evaluate characteristics of body shape, body size, leg metrics, and ostiole development. Obligate myrmecophily significantly influences both body shape and size. Myrmecophilous mealybugs are smaller than their free-living counterparts and are either pyriform or rotund in shape rather than oval. Ant-associates from Rhizoecidae also have significantly reduced anterior pairs of ostioles compared to free-living species. Ostioles are involved in defense against natural enemies and mutualist ants typically protect their partners, presumably supplanting the need for structures like ostioles among myrmecophilous species. We discuss the influence ants have on the evolution of their associates in the context of domestication and offer avenues for future exploration. 

Two new species of root mealybugs (Hemiptera: Rhizoecidae) from South America are described and illustrated based on the morphology of the adult females: Coccidella advena Schneider & LaPolla, sp. nov. from Peru and Rhizoecus peripotaro Schneider & LaPolla, sp. nov. from Guyana and Peru. Both species were collected with colonies of Acropyga ants (Hymenoptera: Formicidae) but only R. peripotaro was found to be trophobiotic; C. advena was ignored by the ants and is considered to be free-living. A guide to aid in identification is provided for each species.  

We describe a new pair of trophobiotic partners from the ant genus Acropyga and the root mealybug genus Neochavesia . A recent field study on Acropyga ants and associated root mealybugs, conducted in the Peruvian Amazon, led to the discovery of Acropyga manuense LaPolla & Schneider, sp. nov. and its root mealybug symbiont Neochavesia podexuta Schneider & LaPolla, sp. nov. The new root mealybug belongs to the family Xenococcidae, whose members are all obligate associates of Acropyga ants. Providing joint descriptions of new mutualist partners in the same article is a novel approach for this system, and it offers benefits to the ongoing study of mutualism and patterns of association among these symbiotic ants and scales. Here, we also begin to revise the species-group composition of Acropyga by establishing the smithii species-group, and we provide updated information to aid in identifying the new ant species and root mealybug species. 

We describe five new Neotropical species ofRipersiellaliving in association withAcropygaants:R. campensissp. nov.,R. illicianssp. nov.,R. montanaesp. nov.,R. pediandensissp. nov., andR. telaliasp. nov.We also redescribeR. andensisandR. colombiensisbased on type specimens and other collections. Together, these seven species form a morphologically similar group that we informally refer to as theandensis-complex ofRipersiella. All members of theandensis-complex are confirmed or are speculated to be mutualists ofAcropygaants. We discuss the implications of these associations and provide an identification key to the Neotropical species ofRipersiellathat are lacking bitubular cerores, including the new species. 

Abstract Background Parasitoidism, a specialized life strategy in which a parasite eventually kills its host, is frequently found within the insect order Hymenoptera (wasps, ants and bees). A parasitoid lifestyle is one of two dominant life strategies within the hymenopteran superfamily Cynipoidea, with the other being an unusual plant-feeding behavior known as galling. Less commonly, cynipoid wasps exhibit inquilinism, a strategy where some species have adapted to usurp other species’ galls instead of inducing their own. Using a phylogenomic data set of ultraconserved elements from nearly all lineages of Cynipoidea, we here generate a robust phylogenetic framework and timescale to understand cynipoid systematics and the evolution of these life histories. Results Our reconstructed evolutionary history for Cynipoidea differs considerably from previous hypotheses. Rooting our analyses with non-cynipoid outgroups, the Paraulacini, a group of inquilines, emerged as sister-group to the rest of Cynipoidea, rendering the gall wasp family Cynipidae paraphyletic. The families Ibaliidae and Liopteridae, long considered archaic and early-branching parasitoid lineages, were found nested well within the Cynipoidea as sister-group to the parasitoid Figitidae. Cynipoidea originated in the early Jurassic around 190 Ma. Either inquilinism or parasitoidism is suggested as the ancestral and dominant strategy throughout the early evolution of cynipoids, depending on whether a simple (three states: parasitoidism, inquilinism and galling) or more complex (seven states: parasitoidism, inquilinism and galling split by host use) model is employed. Conclusions Our study has significant impact on understanding cynipoid evolution and highlights the importance of adequate outgroup sampling. We discuss the evolutionary timescale of the superfamily in relation to their insect hosts and host plants, and outline how phytophagous galling behavior may have evolved from entomophagous, parasitoid cynipoids. Our study has established the framework for further physiological and comparative genomic work between gall-making, inquiline and parasitoid lineages, which could also have significant implications for the evolution of diverse life histories in other Hymenoptera. 

A new myrmecophilous species of root mealybug, Williamsrhizoecus udzungwensis sp. n., is described from individuals found living within a nest of Acropyga silvestrii in the Udzungwa Mountains of Tanzania. Acropyga ants are highly specialized, obligate associates of scale insects, typically members of the scale family Xenococcidae. Acropyga are best known for vertically transmitting trophobiotic partners during their nuptial flights and for housing them within brood chambers. This article presents the first record of trophobiosis between a species of Williamsrhizoecus and Acropyga, and only the second record of an association between Acropyga and rhizoecids in the Old World. This discovery contributes important information about the few species of Rhizoecidae confirmed to engage in these unique symbioses, each putatively the result of a past horizontal transmission event from a xenococcid to a rhizoecid lineage. Included is a discussion on the diagnosis of Williamsrhizoecus and an updated key to the species.