Dragan P. Chobanov

A comparative study of genome organization and inferences for the systematics of two large bushcricket genera of the tribe Barbitistini (Orthoptera: Tettigoniidae: Phaneropterinae)

BackgroundPoecilimon and Isophya are the largest genera of the tribe Barbitistini and among the most systematically complicated and evolutionarily intriguing groups of Palearctic tettigoniids. We examined the genomic organization of 79 taxa with a stable chromosome number using classical (C–banding, silver and fluorochrome staining) and molecular (fluorescence in situ hybridization with 18S rDNA and (TTAGG)n telomeric probes) cytogenetic techniques. These tools were employed to establish genetic organization and differences or similarities between genera or species within the same genus and determine if cytogenetic markers can be used for identifying some taxonomic groups of species.ResultsDifferences between the karyotypes of the studied genera include some general changes in the morphology of the X chromosome in Isophya (in contrast to Poecilimon). The number of major rDNA clusters per haploid genome divided Poecilimon into two main almost equal groups (with either one or two clusters), while two rDNA clusters predominated in Isophya. In both genera, rDNA loci were preferentially located in the paracentromeric region of the autosomes and rarely in the sex chromosomes. Our results demonstrate a coincidence between the location of rDNA loci and active NORs and GC-rich heterochromatin regions. The C/DAPI/CMA3 bands observed in most Poecilimon chromosomes suggest the presence of more families of repetitive DNA sequences as compared to the heterochromatin patterns in Isophya.ConclusionsThe results show both differences and similarities in genome organization among species of the same genus and between genera. Previous views on the systematics and phylogenetic grouping of certain lineages are discussed in light of the present cytogenetic results. In some cases, variation of chromosome markers was observed to correspond with variation in other evolutionary traits, which is related to the processes of ongoing speciation and hybridization in zones of secondary contact. It was concluded that the physical mapping of rDNA sequences and heterochromatin may be used as an additional marker for understanding interspecific relationships in these groups and their routes of speciation.

Interglacial refugia and range shifts of the alpine grasshopper Stenobothrus cotticus (Orthoptera: Acrididae: Gomphocerinae)

A warming climate leads to shifts in distribution ranges to higher latitudes and altitudes. Consequently, cold-adapted alpine species can be trapped in interglacial Holocene refugia on high mountain summits if they fail to expand their ranges to the north. One example is the alpine grasshopper Stenobothrus cotticus. This species was assumed to be endemic to the southwestern Alps (France, Italy). However, we have found a second refugium in the Rila Mountains in southwestern Bulgaria. Analyses of the mitochondrial gene co1 and of phenotypic characters from morphology and behaviour did not reveal differences between the two geographically separated populations of S. cotticus studied. We suppose that S. cotticus had a wider distribution during colder periods, when its range was expanded to lower altitudes. This hypothesis is supported by the current distribution of the closely related montane S. rubicundulus.

Physical mapping of rDNA and satDNA in A and B chromosomes of the grasshopper Eyprepocnemis plorans from a Greek population

Adult males and females of the grasshopper Eyprepocnemis plorans from a Greek population were analysed by C-banding, silver impregnation and double FISH for two DNA probes, i.e. ribosomal DNA (rDNA) and a 180-bp tandem repeat DNA (satDNA). This population shows characteristics of rDNA location in A chromosomes that are intermediate between those previously reported for eastern (Caucasus) and western (Spain and Morocco) populations. The four rDNA clusters revealed by FISH in chromosomes X, 9, 10 and 11 in Greek specimens imply two more than the two observed in chromosomes 9 and 11 in the Caucasus, but less than the 12 observed in all chromosomes in Morocco. Remarkably, the X chromosome bears one of the new rDNA locations in Greece with respect to the Caucasus, but it appears to be inactive, in contrast to X chromosomes in western populations, which are usually active. B chromosomes were very frequent in the Greek population, and three variants differing in size were observed, all of these being largely composed of rDNA, with the exception of a small pericentromeric satDNA cluster. The high B frequency suggests that B chromosomes in this population might behave parasitically, in resemblance to Bs in western populations.

Description of the song of the bush-cricket Saga rammei Kaltenbach, 1965 (Orthoptera: Tettigoniidae)

A detailed description of the spectrographic and oscillographic features of the male calling song of Saga rammei is presented for the first time. The study is based on Macedonian specimens. The song of S. rammei is a mainly amplitude-modulated signal having wide-band frequency spectrum containing well detectable frequency components between 15 kHz and 80 kHz (intensity maximum between 20–30 kHz). The male song is a sequence of echemes, which are composed of evenly and quickly repeated diplo-hemisyllabic syllables. Echemes begin with a gradually crescending initial part that leads to the main part of the echeme, where the peak amplitude of the syllables is nearly constant. This structure is similar to those described in other European Saga species (S. hellenica, S. campbelli, S. natoliae). However, the results suggest that amongst the European Saga species S. rammei produces the shortest echemes composed of the lowest number of syllables repeated with the highest syllable repetition rate and that the species sings with the shortest echeme repetition period. Those quantitative features make the song of S. rammei distinct and easily recognisable, and therefore could be used by females or males for species recognition.

The Anatolio‐Balkan phylogeographic fault: a snapshot from the genus Isophya (Orthoptera, Tettigoniidae)

Due to active tectonic evolution of the Aegean Area during Miocene and Pleistocene, the Balkans and Anatolia have repeatedly connected and disconnected causing isolation and secondary contact of populations along the present Dardanelles – Sea of Marmara – Bosphorus waterway. This has led to an outstandingly rich fauna and a reticulate biogeography in the area. A typical example is Orthoptera having here possibly highest diversity within the Western Palaearctic. With the present study, we concentrate on the bush‐cricket genus Isophya, which is characteristic with a large share of endemics in the Balkans and Anatolia. We aim to understand when and how the isolation of marine or other barriers in the region of the Turkish Straits System influenced the evolution of the morpho‐acoustic groups of species found on both sides of the strait. For this purpose, sequences of two mitochondrial (COI and ND2) and two nuclear (ITS1 and ITS2) markers were obtained and used for phylogenetic reconstructions, time estimations for lineage divergence and automatic species delineation (statistical parsimony, GMYC, ABGD) tests. The phylogenetic analyses did not support all the existing morphogroups and was in favour of a geographical subdivision for the young lineages. Automatic species delineation tests confirmed most of the present morpho‐acoustic species and suggested further cryptic species, at the same time unifying some phenetic species. Time estimation analyses suggested time to most recent common ancestor of the genus as 8.28 Ma corresponding to the Late Tortonian. As a result of the study, we reached to the following conclusions: (i) most of the studied phenetic species are monophyletic, but some earlier suggested morpho‐species groups are not, (ii) three main episodes dominate the evolutionary history of Isophya (7.32–5.84 Myr in the Messinian, 2.2–2.5 Myr in the beginning of the Pleistocene and at around 0.75 Ma corresponding to the end of the Mid‐Pleistocene transition), all of which well correlate with episodes of existing terrestrial connections between Anatolia and the Balkans, and (iii) there are several faunal exchanges in both directions between Anatolia and the Balkans.

Re-visiting phylogenetic and taxonomic relationships in the genus Saga (Insecta: Orthoptera).

Twelve of the 13 bushcricket species of the Saga genus are bisexuals and diploids, except the parthenogenetic and tetraploid bush cricket, Saga pedo. Despite a continuous research effort stretching through the 1900s, the taxonomic relationships of the Saga species are still disputed. In this study, our primary aim was to reveal natural relationships of the European Saga species and three of their Asian relatives, with special attention to the problematic taxonomy of two subspecies: S. campbelli campbelli and S. c. gracilis. Following a phylogenetic analysis of eight species, a comprehensive study was carried out on the above three taxa by using acoustic and morphometric approaches in parallel. Our phylogenetic data showed that European Saga species evolved from a monophyletic lineage. The geographical transitional species S. cappadocica was positioned between European and Asian lineages supporting the idea that the European Saga lineage originated phylogeographically from the Asian clade. The above results showed better agreement with the morphological data than with earlier ones based either on karyology or acoustic information only. After reviewing our data, we concluded that Saga pedo has most likely evolved from S. c. gracilis and not from S. rammei or S. ephippigera, as proposed by earlier studies. S. c. gracilis shares the same ITS2 haplotype with S. pedo, indicating that the latter could have evolved from populations of the former, probably through whole genome duplication. Based on acoustic and morphometric differences, we propose to elevate the two subspecies, S. campbelli campbelli and S. c. gracilis, to species level status, as Saga gracilis Kis 1962, and Saga campbelli Uvarov 1921. The present work sets the stage for future genetic and experimental investigations of Saginae and highlights the need for additional comprehensive analysis involving more Asian Saga species.

Geographic distribution of Gryllotalpa stepposa in south-eastern Europe, with first records for Romania, Hungary and Serbia (Insecta, Orthoptera, Gryllotalpidae)

Abstract Described from the steppe zones north of the Black Sea, Caucasus, and central Asia, Gryllotalpa stepposa Zhantiev was recently recorded from a few localities in Greece, R. Macedonia, and Bulgaria. In May 2015, several specimens were collected from Ivrinezu Mare in Romania, which suggested a continuous distribution area of the species, stretching from the central Balkans to central Asia. Thus, to reveal its actual range of occurrence, a survey of several Orthoptera collections became mandatory and, as expected, a large number of misidentified specimens of Gryllotalpa stepposa were discovered, providing new data on the species distribution in south-eastern Europe, including also the first records of this mole cricket in Serbia and Hungary. Here a full locality list is presented of this species west of Ukraine and Moldova and the current geographic distribution of the genus Gryllotalpa in the Balkans is revised. A key for distinguishing the mole crickets in south-eastern Europe and a distribution map for this region are presented.

Review of Poecilimon species with inflated pronotum: description of four new taxa within an acoustically diverse group

Poecilimon Fischer (Orthoptera, Tettigoniidae) consists of about 130 species and a functional taxonomy of the genus requires arranging species into phylogenetic groups. However, this is a task that requires detailed empirical testing. This paper documents data on Poecilimon species with an inflated pronotum. The Poecilimon (Poecilimon) inflatus group is a lineage ranging along a narrow zone in the south-west corner of Anatolia and in Crete plus some other Aegean islands. By producing data of morphology and calling songs of males and responding songs of females the composition and intra-group diversity of P. inflatus group are studied. Both morphology and male calling and female responding songs, exhibited a considerable intra-group diversity. In the light of data obtained the following nomenclatural changes were made. The genus Parapoecilimon Karabağ, 1975 syn. n. is synonymised with Poecilimon Fischer and Parapoecilimon antalyaensis Karabağ, 1975 is given a new combination, Poecilimon antalyaensis (Karabağ, 1975) comb. n. Four new taxa are described in the group: (i) Poecilimon isopterus sp.n.; (ii) Poecilimon inflatus lyciae subsp. n.; (iii) Poecilimon antalyaensis myrae subsp. n., and (iv) Poecilimon antalyaensis anemurium subsp. n. The Poecilimon (P.) inflatus species group consists of the following species: (i) Poecilimon inflatus Brunner von Wattenwyl, 1891; (ii) Poecilimon martinae Heller, 2004; (iii) Poecilimon cretensis Werner, 1903; (iv) Poecilimon antalyaensis (Karabağ, 1975) comb. n.; (v) Poecilimon bilgeri Karabağ, 1953 and (vi) Poecilimon isopterus sp.n. The species group is defined by a combination of characters including the pronotum inflated in metazona and a male cerci mostly black in their apical 1/2-1/3. The male calling song has typically two types of short syllables and the females respond acoustically with very short latency times. By using combination of morphology and song data we suggest three main lineages in the group: (i) P. bilgeri, (ii) P. antalyaensis and (iii) the other four species.

Correction to: Multiple origin of flightlessness in Phaneropterinae bushcrickets and redefinition of the tribus Odonturini (Orthoptera: Tettigonioidea: Phaneropteridae)

The possession of wings and ability to fly are a unifying character of higher insects, but secondary loss of wings is widespread. Within the bushcrickets, the subfamily Phaneropterinae (Orthoptera: Tettigonioidea) comprises more than 2000 predominantly long-winged species in the tropics. However, the roughly 300 European representatives are mainly short-winged. The systematics of these radiations have been unclear, leading to their unreliable formal treatment, which has hindered analysis of the evolutionary patterns of flight loss. A molecular phylogeny is presented for 42 short-winged species and members of all European long-winged genera based on the combined data from three nuclear gene sequences (18S, H3, ITS2). We found four phylogenetic lineages: (i) the first included the short-wing species of the genus Odontura; (ii) a further branch is represented by the South-American short-winged Cohnia andeana; (iii) an assemblage of long-wing taxa with a deep branching pattern includes the members of the tribes Acrometopini, Ducetiini, Phaneropterini, and Tylopsidini; (iv) a large group contained all short-winged taxa of the tribe Barbitistini. Phaneropterinae flightlessness originated twice in the Western Palaearctic, with a number of mainly allo- and parapatrically distributed species of the Barbistini in Southeastern Europe, and the Middle East and a limited number of Odontura species in Northern Africa and Southwestern Europe. Both short-winged lineages are well separated, which makes it necessary to restrict the tribe Odonturini to the West-Palaearctic genus Odontura. Other flightless genera previously included in the Odonturini are placed as incertae sedis until their phylogenetic position can be established.

New data on the bush-cricket Montana medvedevi (Orthoptera: Tettigoniidae), critically endangered in Europe (EU 28), and a comparison of its song with all known song patterns within the genus

Montana medvedevi is reported for the first time from Serbia. New information about the distribution, morphology and song of this species is discussed. The song of M. medvedevi is different from that of all other members of the genus, all figured for comparison. Montana is quite diverse regarding the amplitude pattern of the calling song of its members (known in 15 species). Surprisingly, some Montana species seem to have two song patterns, one produced during the day and one at night.