Specialized ovipositor sensilla of Cretaceous wasps (Insecta: Hymenoptera) possibly reveal a unique way of host detection.

Insects have evolved complex sensory systems that are important for feeding, defence and reproduction. Parasitoid wasps often spend much time and effort in searching for concealed hosts with the help of specialized sensilla. However, the early evolution of such behaviour and sensilla is poorly known. We describe two fossil female wasps, †Tichostephanus kachinensis sp. nov. and †Tichostephanus longus sp. nov., from mid-Cretaceous Kachin amber. Phylogenetic analyses based on morphological data retrieved †Tichostephanus as deeply nested within Evanioidea and closely related to extant Gasteruptiidae and Evaniidae. Both of these Cretaceous wasps possess features, e.g. coronal tubercles and flexible ovipositor sheaths, that indicate that they might have laid eggs in wood where their larvae possibly parasitized insect larvae. They have a peculiar and unique 'bottle brush' of sensilla close to the apex of their ovipositor sheaths, which has not been observed in any extant parasitoid wasps. These sensilla comprise many regularly arranged plate-shaped setae, attached in relatively large sockets and with rows of longitudinal ridges. Such specialized sensilla perhaps served to enhance the ability to detect hosts inside wood.

Eocene amber provides the first fossil record and bridges distributional gap in the rare genus Robsonomyia (Diptera: Keroplatidae).

Until now, the genus Robsonomyia was represented by two extant species: R. reducta Matile & Vockeroth, 1980 from North America and R. sciaraeformis (Okada, 1939) from Asia. This paper presents the first fossil members of the genus Robsonomyia, which is also the first record from Europe. Two new fossil species from Baltic amber are described: R. baltica Pelczynska, Krzeminski & Blagoderov, sp. nov. and R. henningseni Pelczynska, Krzeminski & Blagoderov, sp. nov.. The presence of fossil Robsonomyia spp. on the European continent suggests Holarctic distribution of the genus in the past. We also discuss possible pathways of its intercontinental dispersion.

A revised terminology for male genitalia in Hymenoptera (Insecta), with a special emphasis on Ichneumonoidea.

Applying consistent terminology for morphological traits across different taxa is a highly pertinent task in the study of morphology and evolution. Different terminologies for the same traits can generate bias in phylogeny and prevent correct homology assessments. This situation is exacerbated in the male genitalia of Hymenoptera, and specifically in Ichneumonoidea, in which the terminology is not standardized and has not been fully aligned with the rest of Hymenoptera. In the current contribution, we review the terms used to describe the skeletal features of the male genitalia in Hymenoptera, and provide a list of authors associated with previously used terminology. We propose a unified terminology for the male genitalia that can be utilized across the order and a list of recommended terms. Further, we review and discuss the genital musculature for the superfamily Ichneumonoidea based on previous literature and novel observations and align the terms used for muscles across the literature.

Morphology of sting apparatus of Chrysidoidea (Hymenoptera, Aculeata).

The main synapomorphy for Aculeata is the sting apparatus, which allows the female to envenom potential prey or hosts. The sting is the modified ovipositor which is not used for laying eggs anymore. Here, we explore the morphology of the sting apparatus within the families of Chrysidoidea. 27 skeletal structures were recognized, including three (dp1vf, dorsal projection of first valvifer; ppa, projection of posterior area of the second valvifer; vl9, ventral lap of tergite 9) that have not been observed previously, and 13 pairs of muscles, including four (superior dorsal T9-2vf (M5); inferior dorsal T9-2vf (M6); postero-lateral T9-2vf/mbr (M9); anterolateral 2vf/bl-2vv/fu (M11)) that have not been observed previously. Very conserved morphological patterns were observed; character support in the sting apparatus was found at the subfamily level, and within three families at the genus level. In addition, we describe the variation within the sting apparatus structures and musculature, propose evolutionary hypotheses about the function and evolution of the structures, and summarize phylogenetic conclusions for Chrysidoidea.

Two new species of Ophrynopus Konow, 1897 (Hymenoptera: Orussidae), with a new definition of the genus.

Two species of Orussidae are described: Ophrynopus rufocephalus new species and Ophrynopus savinai new species. The new taxa are analyzed with an existing data set for the Orussidae of the world. The results of the analyses indicate that the generic classification within the ophrynopine clade needs to be adjusted. Argentophrynopus Vilhelmsen D.R. Smith, 2002 new synonym and Ophrella Middlekauff, 1985 new synonym are treated as junior synonyms of Ophrynopus Konow, 1897. This results in the following additional taxonomic changes: Ophrynopus amazonicus (Westwood, 1874) combination reestablished, Ophrynopus eldorado (Vilhelmsen, 2013) new combination, Ophrynopus enigmus (Vilhelmsen D.R. Smith, 2002) new combination, Ophrynopus gauldi (Vilhelmsen D.R. Smith, 2002) new combination, Ophrynopus seagi (Vilhelmsen, 2016) new combination. Furthermore, Ophrynopus andrei Konow, 1897 new synonym is regarded as a junior synonym of Ophrynopus fulvostigma (Westwood, 1874). A revised key to Ophrynopus spp. is presented.

The sawflies and woodwasps (Hymenoptera: 'Symphyta') of Colombia.

A survey of the 'Symphyta' of Colombia is conducted, based on information from literature as well as on examination of over 2,000 specimens from the major Colombian entomological collections. A total of 127 species are recorded from Colombia, representing six families: Argidae (48 species), Tenthredinidae (37) Pergidae (37), Xiphydriidae (3 species), Siricidae (1 species) and Orussidae (1 species). 11 genera and 68 species are new records for Colombia, doubling the number of previously reported species. Heteroperreyia (Pergidae) is recorded for the first time in northern South America. Most records and species are concentrated in the Andean region. Four new species are described: Acrogymnidia catalina Malagón-Aldana, sp. nov., Ptenos amazonicus Malagón-Aldana, sp. nov. (Argidae), Heteroperreyia andina Malagón-Aldana, sp. nov. (Pergidae) and Derecyrta risaraldensis Malagón-Aldana, sp. nov. (Xiphydriidae). The following taxonomic changes are proposed, and lectotypes designated for all these nominal taxa: Dochmioglene suppar (Konow, 1903), comb. n., Plaumanniana parmata (Konow, 1903), comb. n., and Proselandria analis (Fabricius, 1804), comb. n.; Plaumanniana biclinia (Konow, 1899) = Stromboceros marcidus Konow, 1899, syn. n.; Proselandria analis (Fabricius, 1804) = Stromboceros brevispinis Konow, 1908, syn. n., Monophadnus trichiotomus Cameron, 1911, syn. n. and Romaniola amazonica Forsius, 1925, syn. n.

A Nonstationary Markov Model Detects Directional Evolution in Hymenopteran Morphology.

Directional evolution has played an important role in shaping the morphological, ecological, and molecular diversity of life. However, standard substitution models assume stationarity of the evolutionary process over the time scale examined, thus impeding the study of directionality. Here we explore a simple, nonstationary model of evolution for discrete data, which assumes that the state frequencies at the root differ from the equilibrium frequencies of the homogeneous evolutionary process along the rest of the tree (i.e., the process is nonstationary, nonreversible, but homogeneous). Within this framework, we develop a Bayesian approach for testing directional versus stationary evolution using a reversible-jump algorithm. Simulations show that when only data from extant taxa are available, the success in inferring directionality is strongly dependent on the evolutionary rate, the shape of the tree, the relative branch lengths, and the number of taxa. Given suitable evolutionary rates (0.1-0.5 expected substitutions between root and tips), accounting for directionality improves tree inference and often allows correct rooting of the tree without the use of an outgroup. As an empirical test, we apply our method to study directional evolution in hymenopteran morphology. We focus on three character systems: wing veins, muscles, and sclerites. We find strong support for a trend toward loss of wing veins and muscles, while stationarity cannot be ruled out for sclerites. Adding fossil and time information in a total-evidence dating approach, we show that accounting for directionality results in more precise estimates not only of the ancestral state at the root of the tree, but also of the divergence times. Our model relaxes the assumption of stationarity and reversibility by adding a minimum of additional parameters, and is thus well suited to studying the nature of the evolutionary process in data sets of limited size, such as morphology and ecology.

A new Orussus species from South Korea, and a key to the East Asian Orussidae (Hymenoptera).

Orussus melanosoma Lee & Wei, sp. nov. from South Korea is described and illustrated. Phylogenetic analyses place the new species basally in Orussus, together with other species from the Far East. A key to species of Orussidae from the eastern Palaearctic is provided. 

Baltorussus total makeover: rejuvenation and sex change in an ancient parasitoid wasp lineage.

The Orussidae is a small and rare but phylogenetically important family of parasitoid wasps. The fossil record of the family is also very poor. Baltorussus velteni was described from Baltic amber from an allegedly female specimen. This and another recently discovered specimen are examined with microCT scanning and standard microscopy. We reveal that both the holotype and the new specimen are actually males. Furthermore, the results of the microCT scanning allow us to integrate the fossils in a morphological data set assembled for extant Orussidae. Phylogenetic analyses consistently retrieve Baltorussus as a separate basal lineage within the crown group, whereas two Cretaceous fossils are placed as stem group orussids and a Dominican amber fossil in an extant genus. Based on the positions of the fossils, we estimate that the extant Orussidae radiated in the mid-Cretaceous (approx. 100 Ma ago). This is considerably younger than a previously suggested Early Jurassic date (180 Ma ago), which was primarily based on biogeographic evidence.

The hymenopteran tree of life: evidence from protein-coding genes and objectively aligned ribosomal data.

Previous molecular analyses of higher hymenopteran relationships have largely been based on subjectively aligned ribosomal sequences (18S and 28S). Here, we reanalyze the 18S and 28S data (unaligned about 4.4 kb) using an objective and a semi-objective alignment approach, based on MAFFT and BAli-Phy, respectively. Furthermore, we present the first analyses of a substantial protein-coding data set (4.6 kb from one mitochondrial and four nuclear genes). Our results indicate that previous studies may have suffered from inflated support values due to subjective alignment of the ribosomal sequences, but apparently not from significant biases. The protein data provide independent confirmation of several earlier results, including the monophyly of non-xyelid hymenopterans, Pamphilioidea + Unicalcarida, Unicalcarida, Vespina, Apocrita, Proctotrupomorpha and core Proctotrupomorpha. The protein data confirm that Aculeata are nested within a paraphyletic Evaniomorpha, but cast doubt on the monophyly of Evanioidea. Combining the available morphological, ribosomal and protein-coding data, we examine the total-evidence signal as well as congruence and conflict among the three data sources. Despite an emerging consensus on many higher-level hymenopteran relationships, several problems remain unresolved or contentious, including rooting of the hymenopteran tree, relationships of the woodwasps, placement of Stephanoidea and Ceraphronoidea, and the sister group of Aculeata.

A total-evidence approach to dating with fossils, applied to the early radiation of the hymenoptera.

Phylogenies are usually dated by calibrating interior nodes against the fossil record. This relies on indirect methods that, in the worst case, misrepresent the fossil information. Here, we contrast such node dating with an approach that includes fossils along with the extant taxa in a Bayesian total-evidence analysis. As a test case, we focus on the early radiation of the Hymenoptera, mostly documented by poorly preserved impression fossils that are difficult to place phylogenetically. Specifically, we compare node dating using nine calibration points derived from the fossil record with total-evidence dating based on 343 morphological characters scored for 45 fossil (4--20 complete) and 68 extant taxa. In both cases we use molecular data from seven markers (∼5 kb) for the extant taxa. Because it is difficult to model speciation, extinction, sampling, and fossil preservation realistically, we develop a simple uniform prior for clock trees with fossils, and we use relaxed clock models to accommodate rate variation across the tree. Despite considerable uncertainty in the placement of most fossils, we find that they contribute significantly to the estimation of divergence times in the total-evidence analysis. In particular, the posterior distributions on divergence times are less sensitive to prior assumptions and tend to be more precise than in node dating. The total-evidence analysis also shows that four of the seven Hymenoptera calibration points used in node dating are likely to be based on erroneous or doubtful assumptions about the fossil placement. With respect to the early radiation of Hymenoptera, our results suggest that the crown group dates back to the Carboniferous, ∼309 Ma (95% interval: 291--347 Ma), and diversified into major extant lineages much earlier than previously thought, well before the Triassic. [Bayesian inference; fossil dating; morphological evolution; relaxed clock; statistical phylogenetics.].

Phylogenetic relationships among superfamilies of Hymenoptera.

The first comprehensive analysis of higher-level phylogeny of the order Hymenoptera is presented. The analysis includes representatives of all extant superfamilies, scored for 392 morphological characters, and sequence data for four loci (18S, 28S, COI and EF-1α). Including three outgroup taxa, 111 terminals were analyzed. Relationships within symphytans (sawflies) and Apocrita are mostly resolved. Well supported relationships include: Xyeloidea is monophyletic, Cephoidea is the sister group of Siricoidea + [Xiphydrioidea + (Orussoidea + Apocrita)]; Anaxyelidae is included in the Siricoidea, and together they are the sister group of Xiphydrioidea + (Orussoidea + Apocrita); Orussoidea is the sister group of Apocrita, Apocrita is monophyletic; Evanioidea is monophyletic; Aculeata is the sister group of Evanioidea; Proctotrupomorpha is monophyletic; Ichneumonoidea is the sister group of Proctotrupomorpha; Platygastroidea is sister group to Cynipoidea, and together they are sister group to the remaining Proctotrupomorpha; Proctotrupoidea s. str. is monophyletic; Mymarommatoidea is the sister group of Chalcidoidea; Mymarommatoidea + Chalcidoidea + Diaprioidea is monophyletic. Weakly supported relationships include: Stephanoidea is the sister group of the remaining Apocrita; Diaprioidea is monophyletic; Ceraphronoidea is the sister group of Megalyroidea, which together form the sister group of [Trigonaloidea (Aculeata + Evanioidea)]. Aside from paraphyly of Vespoidea within Aculeata, all currently recognized superfamilies are supported as monophyletic. The diapriid subfamily Ismarinae is raised to family status, Ismaridae stat. nov. © The Will Henning Society 2011.

Per arborem ad astra: morphological adaptations to exploiting the woody habitat in the early evolution of Hymenoptera.

We survey morphological features of larval and adult wasps that undergo their entire larval development inside wood and interpret them in view of the lifestyle. The evolution of some of the characters is explored by mapping them on a recently published phylogeny of Hymenoptera. Based on this phylogeny, it is reasonable to assume that wood-living wasps evolved from a xylophagous/mycetophagous stage as displayed by woodwasps to a carnivorous/parasitoid lifestyle, preying on woodboring insect larvae. The latter mode of life is probably ancestral to the Apocrita which comprise the majority of the order; they share this lifestyle with their sister group, the Orussidae. However, most apocritan wasps have radiated into other habitats, the Orussidae and Stephanidae apparently being the only taxa that have retained the ancestral lifestyle of carnivorous wasps. Other apocritan lineages associated with wood (e.g., Aulacidae, Megalyridae, basal Cynipoidea and some Ichneumonoidea and Chalcidoidea) possibly entered this habitat secondarily and independently acquired morphological traits associated with it. The woody habitat was occupied by Hymenoptera during a crucial stage in their evolution where the transition from the phytophagous to carnivorous lifestyle took place. The anatomy of both larva and adults was extensively transformed in the process.

Morphological and molecular evidence converge upon a robust phylogeny of the megadiverse Holometabola.

We present the largest morphological character set ever compiled for Holometabola. This was made possible through an optimized acquisition of data. Based on our analyses and recently published hypotheses based on molecular data, we discuss higher-level phylogeny and evolutionary changes. We comment on the information content of different character systems and discuss the role of morphology in the age of phylogenomics. Microcomputer tomography in combination with other techniques proved highly efficient for acquiring and documenting morphological data. Detailed anatomical information (356 characters) is now available for 30 representatives of all holometabolan orders. A combination of traditional and novel techniques complemented each other and rapidly provided reliable data. In addition, our approach facilitates documenting the anatomy of model organisms. Our results show little congruence with studies based on rRNA, but confirm most clades retrieved in a recent study based on nuclear genes: Holometabola excluding Hymenoptera, Coleopterida (= Strepsiptera + Coleoptera), Neuropterida excl. Neuroptera, and Mecoptera. Mecopterida (= Antliophora + Amphiesmenoptera) was retrieved only in Bayesian analyses. All orders except Megaloptera are monophyletic. Problems in the analyses are caused by taxa with numerous autapomorphies and/or inapplicable character states due to the loss of major structures (such as wings). Different factors have contributed to the evolutionary success of various holometabolan lineages. It is likely that good flying performance, the ability to occupy different habitats as larvae and adults, parasitism, liquid feeding, and co-evolution with flowering plants have played important roles. We argue that even in the "age of phylogenomics", comparative morphology will still play a vital role. In addition, morphology is essential for reconstructing major evolutionary transformations at the phenotypic level, for testing evolutionary scenarios, and for placing fossil taxa. © The Willi Hennig Society 2010.

Head capsule characters in the Hymenoptera and their phylogenetic implications.

The head capsule of a taxon sample of three outgroup and 86 ingroup taxa is examined for characters of possible phylogenetic significance within Hymenoptera. 21 morphological characters are illustrated and scored, and their character evolution explored by mapping them onto a phylogeny recently produced from a large morphological data set. Many of the characters are informative and display unambiguous changes. Most of the character support demonstrated is supportive at the superfamily or family level. In contrast, only few characters corroborate deeper nodes in the phylogeny of Hymenoptera.

A molecular phylogeny of Dorylus army ants provides evidence for multiple evolutionary transitions in foraging niche.

BACKGROUND: Army ants are the prime arthropod predators in tropical forests, with huge colonies and an evolutionary derived nomadic life style. Five of the six recognized subgenera of Old World Dorylus army ants forage in the soil, whereas some species of the sixth subgenus (Anomma) forage in the leaf-litter and some as conspicuous swarm raiders on the forest floor and in the lower vegetation (the infamous driver ants). Here we use a combination of nuclear and mitochondrial DNA sequences to reconstruct the phylogeny of the Dorylus s.l. army ants and to infer the evolutionary transitions in foraging niche and associated morphological adaptations. RESULTS: Underground foraging is basal and gave rise to leaf-litter foraging. Leaf-litter foraging in turn gave rise to two derived conditions: true surface foraging (the driver ants) and a reversal to subterranean foraging (a clade with most of the extant Dorylus s.s. species). This means that neither the subgenus Anomma nor Dorylus s.s. is monophyletic, and that one of the Dorylus s.s. lineages adopted subterranean foraging secondarily. We show that this latter group evolved a series of morphological adaptations to underground foraging that are remarkably convergent to the basal state. CONCLUSION: The evolutionary transitions in foraging niche were more complex than previously thought, but our comparative analysis of worker morphology lends strong support to the contention that particular foraging niches have selected for very specific worker morphologies. The surprising reversal to underground foraging is therefore a striking example of convergent morphological evolution.

Flexible ovipositor sheaths in parasitoid Hymenoptera (Insecta).

The structure of the ovipositor sheaths is examined in a number of parasitic wasps as well as a few non-parasitic taxa. Parasitic wasps in the families Aulacidae, Braconidae, Ichneumonidae, Megalyridae, and Stephanidae with a very elongate, external ovipositor have the lateral wall of the sheath finely transversely subdivided by narrow furrows. This makes the sheath highly flexible, allowing it to support the ovipositor proper during ovipositing. The taxa having such a flexible sheath all drill into wood to lay their eggs. Support at the tip of the ovipositor is crucial in the initial stages of oviposition. The flexible ovipositor sheath is possibly a very ancient trait, arising prior to the radiation of extant Apocrita. This is corroborated by their presence in fossil Hymenoptera from the Upper Jurassic. The occurrence of short and/or concealed ovipositors with rigid sheaths in many extant apocritan taxa must therefore be assumed to be the result of multiple reversals.