Evolution of mitogenomic gene order in Orthoptera.

Mitochondrial gene order has contributed to the elucidation of evolutionary relationships in several animal groups. It generally has found its application as a phylogenetic marker for deep nodes. Yet, in Orthoptera limited research has been performed on the gene order, although the group represents one of the oldest insect orders. We performed a comprehensive study on mitochondrial genome rearrangements (MTRs) within Orthoptera in the context of mitogenomic sequence-based phylogeny. We used 280 published mitogenome sequences from 256 species, including three outgroup species, to reconstruct a molecular phylogeny. Using a heuristic approach, we assigned MTR scenarios to the edges of the phylogenetic tree and reconstructed ancestral gene orders to identify possible synapomorphies in Orthoptera. We found all types of MTRs in our dataset: inversions, transpositions, inverse transpositions, and tandem-duplication/random loss events (TDRL). Most of the suggested MTRs were in single and unrelated species. Out of five MTRs which were unique in subgroups of Orthoptera, we suggest four of them to be synapomorphies; those were in the infraorder Acrididea, in the tribe Holochlorini, in the subfamily Pseudophyllinae, and in the two families Phalangopsidae and Gryllidae or their common ancestor (leading to the relationship ((Phalangopsidae + Gryllidae) + Trigonidiidae)). However, similar MTRs have been found in distant insect lineages. Our findings suggest convergent evolution of specific mitochondrial gene orders in several species, deviant from the evolution of the mitogenome DNA sequence. As most MTRs were detected at terminal nodes, a phylogenetic inference of deeper nodes based on MTRs is not supported. Hence, the marker does not seem to aid resolving the phylogeny of Orthoptera, but adds further evidence for the complex evolution of the whole group, especially at the genetic and genomic levels. The results indicate a high demand for more research on patterns and underlying mechanisms of MTR events in Orthoptera.

Barcoding Fails to Delimit Species in Mongolian Oedipodinae (Orthoptera, Acrididae).

Mongolia, a country in central Asia, with its vast grassland areas represents a hotspot for Orthoptera diversity, especially for the Acrididae. For Mongolia, 128 Acrididae species have been documented so far, of which 41 belong to the subfamily Oedipodinae (band-winged grasshoppers). Yet, few studies concerning the distribution and diversity of Oedipodinae have been conducted in this country. Molecular genetic data is almost completely absent, despite its value for species identification and discovery. Even, the simplest and most used data, DNA barcodes, so far have not been generated for the local fauna. Therefore, we generated the first DNA barcode data for Mongolian band-winged grasshoppers and investigated the resolution of this marker for species delimitation. We were able to assemble 105 DNA barcode (COI) sequences of 35 Oedipodinae species from Mongolia and adjacent countries. Based on this data, we reconstructed maximum likelihood and Bayesian inference phylogenies. We, furthermore, conducted automatic barcode gap discovery and used the Poisson tree process (PTP) for species delimitation. Some resolution was achieved at the tribe and genus level, but all delimitation methods failed to differentiate species by using the COI region. This lack of resolution may have multiple possible reasons, which likely differ between taxa: the lack of resolution in the Bryodemini may be partially explained by their massive genomes, implying the potential presence of large numbers of pseudogenes, while within the Sphingonotini incomplete lineage sorting and incorrect taxonomy are more likely explanations for the lack of signal. Further studies based on a larger number of gene fragments, including nuclear DNA, are needed to distinguish the species also at the molecular level.

Type catalogue of Oedipodinae (Orthoptera: Acrididae) present in Naturalis Biodiversity Center Leiden (Netherlands).

A type catalogue of Oedipodinae in the collection of Naturalis Biodiversity Center is presented altogether 82 type specimens including 13 primary types and 5 junior synonyms: holotypes (4 species), neotype (1 species), lectotypes (2 species, 1 subspecies), and syntypes (5 species). Furthermore 50 additional secondary type specimens were recorded. Here, we present the full type material catalogue including a locality map of all species and pictures of the 15 primary type species.

New estimates of genome size in Orthoptera and their evolutionary implications.

Animal genomes vary widely in size, and much of their architecture and content remains poorly understood. Even among related groups, such as orders of insects, genomes may vary in size by orders of magnitude-for reasons unknown. The largest known insect genomes were repeatedly found in Orthoptera, e.g., Podisma pedestris (1C = 16.93 pg), Stethophyma grossum (1C = 18.48 pg) and Bryodemella holdereri (1C = 18.64 pg). While all these species belong to the suborder of Caelifera, the ensiferan Deracantha onos (1C = 19.60 pg) was recently found to have the largest genome. Here, we present new genome size estimates of 50 further species of Ensifera (superfamilies Gryllidea, Tettigoniidea) and Caelifera (Acrididae, Tetrigidae) based on flow cytometric measurements. We found that Bryodemella tuberculata (Caelifera: Acrididae) has the so far largest measured genome of all insects with 1C = 21.96 pg (21.48 gBp). Species of Orthoptera with 2n = 16 and 2n = 22 chromosomes have significantly larger genomes than species with other chromosome counts. Gryllidea genomes vary between 1C = 0.95 and 2.88 pg, and Tetrigidae between 1C = 2.18 and 2.41, while the genomes of all other studied Orthoptera range in size from 1C = 1.37 to 21.96 pg. Reconstructing ancestral genome sizes based on a phylogenetic tree of mitochondrial genomic data, we found genome size values of >15.84 pg only for the nodes of Bryodemella holdereri / B. tuberculata and Chrysochraon dispar / Euthystira brachyptera. The predicted values of ancestral genome sizes are 6.19 pg for Orthoptera, 5.37 pg for Ensifera, and 7.28 pg for Caelifera. The reasons for the large genomes in Orthoptera remain largely unknown, but a duplication or polyploidization seems unlikely as chromosome numbers do not differ much. Sequence-based genomic studies may shed light on the underlying evolutionary mechanisms.

The Genomics of Isolated Populations of Gampsocleis glabra (Orthoptera: Tettigoniidae) in Central and Western Europe.

Habitat destruction and fragmentation are among the major current threats to global biodiversity. Fragmentation may also affect species with good dispersal abilities. We study the heath bushcricket Gampsocleis glabra, a specialist of steppe-like habitats across Europe that are highly fragmented, investigating if these isolated populations can be distinguished using population genomics and if there are any traces of admixture or dispersal among them. We try to answer these questions using genome-wide SNP data generated with ddRAD sequencing. We calculated F-statistics and visualized differentiation using STRUCTURE plots. While limited by the difficulty of sampling this threatened species, our results show that all populations except one that was represented by a singleton were clearly distinct, with pairwise FST values between 0.010 and 0.181. STRUCTURE indicated limited but visible admixture across most populations and probably also an exchange of individuals between populations of Germany and The Netherlands. We conclude that in G. glabra, a certain amount of gene flow has persisted, at least in the past, also among populations that are isolated today. We also detect a possibly more recent dispersal event between a population in The Netherlands and one in Germany, which may be human aided. We suggest that the conservation of larger populations should be maintained, that efforts should be taken to restore abandoned habitat, that the preservation even of small habitat fragments may be beneficial for the conservation of this species, and that these habitats should be regularly monitored for possible (re-)colonization.

Taxonomic review of the genus Thalpomena Saussure, 1884 with new synonyms.

The genus Thalpomena Saussure, 1884 is distributed in North Africa, Somalia and Ethiopia. It currently contains nine species, including one species with four subspecies; Seven of them (including one with four subspecies) are distributed in the Atlas Mountains, one in Libya and one (originally described in the genus Vosseleria) in the Somali Highlands. In this study, we propose taxonomic changes based on morphological, genetic, ecological and morphometric data from a previous study. The following species remain valid: Thalpomena algeriana (Lucas, 1849); Thalpomena azureipennis Uvarov, 1927; Thalpomena coerulescens Uvarov, 1923; Thalpomena dernensis (Werner, 1908); and Thalpomena viridipennis Uvarov, 1927. The following names are proposed here as junior synonyms of T. algeriana: Thalpomena algeriana intermedia Dirsh, 1949 (new synonym), Thalpomena algeriana montana Dirsh, 1949 (new synonym), Thalpomena coeruleipennis Finot, 1895 (new synonym), Thalpomena deserta Dirsh, 1949 (new synonym). Thalpomena rungsi Dirsh, 1949 is a new synonym of T. azureipennis; Thalpomena algeriana maroccana Dirsh, 1949 is a new synonym of T. viridipennis. The only East African representative of the genus, Thalpomena schulthessi (Uvarov, 1923), is transferred to the genus Vosseleriana (new combination).

A faunistic review of the Iranian species of Sphingonotus (Orthoptera, Oedipodinae) with an online key to species.

Sphingonotus is a species-rich genus of band-winged grasshoppers (Oedipodinae), comprising more than 170 species, with its diversity hotspots in the Mediterranean, and in Central and Eastern Asia. Iran represents one of the countries with the highest species diversity for the genus with a total of 31 recorded species. However, no study so far has provided a faunistic overview and no identification keys are available. Here, we present an annotated list of all Sphingonotus species found in Iran derived from records from field observations, museum collections and literature data. Based on morphological and distribution data we synonymize Sphingonotus intutus Saussure, 1888 syn. nov. under Sphingonotus nebulosus persa Saussure, 1884 and Sphingonotus obscuratus transcaspicus Uvarov, 1925 syn. nov. under Sphingonotus obscuratus brunneri Saussure, 1884. We present images of representative specimens (mostly types) of all species, as well as distribution maps and ecological data. Finally, we provide an online key to all known species of Sphingonotus from Iran, which will continuously be updated.