Pleistocene phylogeography and cryptic diversity of a tiger beetle, Calomera littoralis, in North-Eastern Mediterranean and Pontic regions inferred from mitochondrial COI gene sequences

Integrative species delimitation reveals fine-scale allopatric speciation in a good-flying insect: a case study on

Alpha taxonomy is fundamental for many biological fields. Delineation of the species boundary, however, can be challenging in a species complex, where different species share a similar morphology and diagnostic characters may not be available. In this context, integrative approaches that incorporate molecular and morphological data sets, and account for speciation history can be helpful to alpha taxonomy. Different approaches to species delimitation based on different assumptions are complementary and by integrating the results from multiple approaches we can generate a more reliable and objective taxonomic decision. In this study, we applied three molecular approaches to species delimitation and inferred the demographic history based on an isolation with migration model to test a morphologically based taxonomic hypothesis for the Cylindera pseudocylindriformis complex. We discuss the association between genetic divergence and microhabitat specialisation, and further corroborate that C. subtilis sp. nov. is a valid new species by integrating the results from model-based species delimitation and the genealogical divergence index. We argue that genetic endemism can occur at a small geographic scale, even in a winged insect like tiger beetles. Our results also indicated that there may still be undocumented species diversity of Taiwanese Cylindera remaining to be discovered. ZooBank LSID: urn:lsid:zoobank.org:pub:9DEC1432-365C-4872-8D06-73B95F30624F

Hide-and-seek with hoverflies: Merodon aureus – a species, a complex or a subgroup?

In order to disentangle the currently confused interpretations and nomenclature of Merodon aureus and M. aeneus, we have reviewed all existing type material and species names known to us as assigned synonyms of these taxa. We resolve M. aeneus as being a junior synonym of M. aureus. We designate a lectotype for M. aureus and a neotype for M. aeneus. Additionally, we provide evidence that M. aureus, together with two newly discovered taxa (M. calidus sp. nov. and M. ortus sp. nov.), represent a complex of cryptic species named the M. aureus species complex. This complex, together with the M. unicolor species complex and the species M. pumilus, is part of the M. aureus subgroup. The M. unicolor species complex comprises two cryptic species: M. unicolor and M. albidus sp. nov. The new species are described by applying an integrative taxonomic approach using several data types (COI and 28S rRNA genes, geometric morphometry of the wings, ecological and distributional data). Based on the COI gene sequence analysis and distributional data, the pupa previously described as an immature stage of the species M. aureus is redefined as an immature stage of the new species M. calidus. Speciation within the M. aureus subgroup is discussed in the context of the phylogeographic history in the studied region.

Delineation of two new, highly similar species of Taiwanese Cylindera tiger beetles (Coleoptera, Carabidae, Cicindelinae) based on morphological and molecular evidence

Tiger beetles have been recognized primarily based on morphological characters. However, the variations of elytral maculation and coloration sometimes lead to misjudgment in species classification and the overlooking of the existence of cryptic species. Recently, specimens of two endemic species of Taiwanese Cylindera, C.sauteri and C.pseudocylindriformis, exhibit morphologically recognizable forms, indicating that some undescribed species may exist. To clarify their taxonomic status, morphological characteristics including male genitalia were examined and two mitochondrial genes, COI and 16S rDNA, and one nuclear 28S rDNA were analyzed. Molecular phylogenetic inferences indicated that both forms in both species are reciprocally monophyletic. Moreover, molecular dating showed the forms diverged approximately 1.3 million years ago. Two new species, Cylinderaooasp. nov. and Cylinderaautumnalissp. nov., are thereby described. The main recognizable characteristics separating C.ooasp. nov. from C.sauteri are the lack of a triangular spot at the middle edge of elytron and the elongated but not rounded subapical spot. For C.autumnalissp. nov., the apical lunula near the elytral suture is thickened but not linear and slender, and its elytra are more metallic brownish than those of C.pseudocylindriformis. Although their aedeagi characteristics are not distinctive, the body size of the proposed two new species is different. Field observation revealed that niche utilization would be relevant for differentiating these closely related species.

From climate zone to microhabitat-environmental factors affecting the coastal distribution of tiger beetles (Coleoptera: Cicindelidae) in the south-eastern European biodiversity hotspot

Background

Tiger beetles (Coleoptera: Cicindelidae) are predatory insects usually occurring in various sandy habitats. In south-eastern Europe, especially in lowland areas located close to the sea coast, the diversity of Cicindelidae is one of the highest in the Palaearctic realm. Although previous studies conducted in different areas of the world show that many species are habitat specialists, unfortunately little is known about environmental factors affecting the diversity and distribution of tiger beetles in this region.

Material and Methods

Habitat preferences for 12 tiger beetles taxa were analysed. Over 100 samples collected in eight countries located in coastal areas of the Black and Mediterranean Seas were studied, for which climate data, macrohabitat types, and soil parameters (soil humidity, salinity, pH, and structure) were investigated.

Results

Most studied Cicindelidae were characterised by narrow or very narrow habitat specialisation and did not co-occur with other ones, including 11 taxa found as habitat specialists occurring only in one or two types of macrohabitat. The most eurythopic species was Calomera littoralis nemoralis which occupied four macrohabitat types. The climatic zone, altitude, and humidity were found as the most important factors in the distribution of the studied tiger beetle species. Salt marshes and sandy sea beaches were noted as the most diverse macrohabitat types.

Discussion

Tiger beetle fauna of south-eastern Europe consists mainly of habitat specialists sensitive to environmental changes, which makes these beetles perfect bioindicators. Moreover, as a great number of studied Cicindelidae taxa occur in habitats which are under a significant human impact, we suggest that in the studied area the group can be successfully used as a flagship taxon for insect and nature conservation.

Catch fast and kill quickly: do tiger beetles use the same strategies when hunting different types of prey?

Background

Tiger beetles (Coleoptera: Cicindelidae) are fast running predatory insects preying on different small insects and other terrestrial arthropods. Prey is located by sight and captured after short and fast pursuit interspersed with pause-and-look behaviour. At least some tiger beetle species can recognise the size and location of prey using memory, which probably allows them to achieve greater hunting success.

Material and Methods

Two eurytopic tiger beetle species known to occur in different types of habitat were used in the study: Cicindela hybrida hybrida, a very common central European beetle found even in artificial habitats such as sandy roads or gravel pits, and Calomera littoralis nemoralis, a species widely distributed in southern European countries and occurring on sandy sea beaches, in salt marshes, as well as on sandy banks of rivers and lakes. Both species are very similar in body size. Specimens used in the study were collected in the field and later tested in the laboratory. We checked whether tiger beetles use different hunting strategies when attacking prey of different sizes and abilities to escape as well as whether the sex of the studied species makes a difference in its hunting behaviour.

Results

The hunting strategies of both tiger beetle species consist of the following main phases: identification, pursuit (often with stops), attack, and optional release of the prey, and then the secondary attack, abandonment of the prey, or consumption of the prey. Considerable differences were noticed in hunting behaviour depending on the type of prey, its movement ability and escape potential. Caterpillars were attacked without pursuit, in the head or directly behind the head where a concentration of nerves and main muscles responsible for walking are located. Effective attacks on beetles were executed at the connection between the thorax and the abdomen. Calomera littoralis strongly preferred slow moving prey, while Cicindela hybrida preferred in equal measure slow moving prey and medium-sized fast moving prey. The experiment on the preferred size of prey indicated small beetles and small caterpillars as favoured by Calomera littoralis, while Cicindela hybrida preferred medium-sized fast moving prey and large caterpillars.

Discussion

The hunting behaviour of Calomera littoralis and Cicindela hybrida is complicated and includes a number of phases allowing to locate, capture and kill the prey. Beetles are able to discriminate between different types of prey and apply different behavioural tactics to hunt it. As the particular strategies are used to increase hunting success, and as a result allow to accumulate energy for future activity of the predator, it can be expected that such a type of hunting behaviour is characteristic also of other tiger beetle species.

The tiger beetles (Coleoptera, Cicindelidae) of the southern Levant and adjacent territories: from cybertaxonomy to conservation biology

The tiger beetles of the southern Levant (Egypt: Sinai, Israel, Jordan) and adjacent regions of the neighboring countries Lebanon, Syria, Iraq, Saudi Arabia and Egypt are reviewed in terms of species taxonomy, ecological and distributional traits and conservation biology. An illustrated dichotomous identification key from the species of this region is provided. Based on the classical identification key, we developed a digital identification application for smartphones and tablets. The species status of Calomeraaulicoides (J.R. Sahlberg, 1913) is (re-) established (stat. rest.) as this taxon can be found sympatrically and parapatrically together with Calomeralittoraliswinkleri (Mandl, 1934). Morphological character states are discussed to identify Cicindelajavetii Chaudoir, 1861 and C.herbacea Klug, 1832. Calomeraaphrodisia (Baudi di Selve, 1864) is recorded for the first time from Israel. The presence of Calomeraaulica (Dejean, 1831) and Grammognathaeuphratica (Dejean, 1822) is confirmed by new records. At least five taxa are threatened or extinct in Israel. For one of these species, Israel has a national responsibility for the conservation as the main part of the distribution range is within this country.

Availability: The application TIGER BEETLE ID for Android devices can be freely downloaded at https://doi.org/10.3897/zookeys.734.21989.suppl1. See also disclaimer of warranties.