Mattesia cf. geminata, an ant-pathogenic neogregarine (Apicomplexa: Lipotrophidae) in two Temnothorax species (Hymenoptera: Formicidae).

An ant-pathogenic neogregarine in Temnothorax affinis and T. parvulus (Hymenoptera: Formicidae) is described based on morphological and ultrastructural characteristics. The pathogen infects the hypodermis of the ants. The infection was mainly synchronous so that only gametocysts and oocysts could be observed simultaneously in the host body. Gametogamy resulted in the formation of two oocysts within a gametocyst. The lemon-shaped oocysts measured 11-13 µm in length and 8-10 µm in width. The surface of the oocysts is not smooth but contains many buds. A ring-shaped line containing rosary-arrayed buds line up in the equatorial plane of the oocyst. These specific characteristics were observed for the first time in neogregarine oocysts from ants. Polar plugs were recognizable clearly by light and electron microscopy. The oocyst wall was quite thick, measuring 775 to 1000 nm. Each oocyst contained eight sporozoites. The neogregarines in the two Temnothorax species show many similarities such as the size and shape of the oocysts, a relatively fragile gametocyst membrane, host affinity, and tissue preference. We identified these neogregarines as Mattesia cf. geminata, which is here recorded from natural ant populations in the Old World for the first time. All neogregarine pathogens infecting ants in nature so far have been recorded from the New World. We present the two ant species, Temnothorax affinis and T. parvulus, as new natural hosts for M. cf. geminata. Furthermore, the morphological and ultrastructural characteristics of the oocyst of M. cf. geminata are documented by scanning and transmission electron microscopy for the first time.

Evolutionary history of inquiline social parasitism in Plagiolepis ants.

Social parasitism, i.e. the parasitic dependence of a social species on another free-living social species, is one of the most intriguing phenomena in social insects. It has evolved to various levels, the most extreme form being inquiline social parasites which have lost the worker caste, and produce only male and female sexual offspring that are reared by the host worker force. The inquiline syndrome has been reported in 4 species within the ant genus Plagiolepis, in Europe. Whether inquiline social parasitism evolved once or multiple times within the genus remains however unknown. To address this question, we generated data for 5 inquiline social parasites - 3 species previously described and 2 unidentified species - and their free-living hosts from Europe, and we inferred their phylogenetic relationships. We tested Emery's rule, which predicts that inquiline social parasites and their hosts are close relatives. Our results show that inquiline parasitism evolved independently at least 5 times in the genus. Furthermore, we found that all inquilines were associated with one of the descendants of their most related free-living species, suggesting sympatric speciation is the main process leading to the emergence of the parasitic species, consistent with the stricter version of Emery's rule.

Ecological diversification preceded geographical expansion during the evolutionary radiation of Cataglyphis desert ants.

Biological diversity often arises as organisms adapt to new ecological conditions (i.e., ecological opportunities) or colonize suitable areas (i.e., spatial opportunities). Cases of geographical expansion followed by local ecological divergence are well described; they result in clades comprising ecologically heterogeneous subclades. Here, we show that the desert ant genus Cataglyphis likely originated in open grassland habitats in the Middle East ∼18 million years ago and became a taxon of diverse species specializing in prey of different masses. The genus then colonized the Mediterranean Basin around 9 million years ago. The result was the rapid accumulation of species, and the appearance of local assemblages containing species from different lineages that still displayed ancestral foraging specialties. These findings highlight that, in Cataglyphis, ecological diversification preceded geographical expansion, resulting in a clade composed of ecologically homogeneous subclades.

A striking color variation is detected in Poneratestacea Emery, 1895 (Hymenoptera, Formicidae) across its Western Palaearctic geographic range.

In this paper, we provide numeric morphology-based evidence that the dark-colored Poneracoarctatavar.lucida Emery, 1898, formerly considered a synonym of P.coarctata (Latreille, 1802), is conspecific with the lighter-colored Poneratestacea Emery, 1895. Species hypotheses are developed via NC-PART clustering, combined with Partitioning Algorithm based on Recursive Thresholding (PART), and via PCA combined with gap statistics. We obtained our results from an extensive dataset from the 10 continuous morphometric traits measured on 165 workers belonging to 73 nest samples. Linear discriminant analysis (LDA) confirmed the grouping of hypotheses generated by exploratory analyses with 100% classification success when all ten morphometric traits were involved. The Anatolian Turkish black and the predominantly European yellow samples, did not separate based on their morphometric characteristics. These two color variations broadly overlap in their geographic range in Anatolian Turkey. The investigated type series of Poneracoarctatavar.lucida Emery, 1898 (collected from Kazakhstan) fell within the P.testacea cluster instead of P.coarctata and is also classified with high certainty as P.testacea by confirmatory LDA. Therefore, we propose the synonymy of Poneracoarctatavar.lucida Emery, 1898 with Poneratestacea Emery, 1895. As no other morphological differences than color patterns were detected between the "black" and "pale" P.testacea samples, we hold that these populations constitute geographically occurring color variations of the same species. Finally, our quantitative morphology-based results show that relying on color patterns is not a robust approach in identifying European Ponera samples, particularly in the east, but using multivariate analyses of morphometric traits is advised instead.

Review of the Camponotus kiesenwetteri group (Hymenoptera, Formicidae) in the Aegean with the description of a new species.

Based on recently collected material, the Camponotus kiesenwetteri group is redefined, and its members known from the Aegean region are diagnosed. Camponotus schulzi sp. nov. is described from Izmir Province, Turkey. Camponotus nadimi Tohmé, 1969 syn. nov. is proposed as a junior synonym of Camponotus libanicus André, 1881 and Camponotus kiesenwetteri cyprius Emery, 1920 syn. nov. as a junior synonym of Camponotus kiesenwetteri (Roger, 1859). A key to workers of species of the C. kiesenwetteri group is provided. Niche modeling analyses are used to account for species habitat suitability across the Aegean region.

The evolution of invasiveness in garden ants.

It is unclear why some species become successful invaders whilst others fail, and whether invasive success depends on pre-adaptations already present in the native range or on characters evolving de-novo after introduction. Ants are among the worst invasive pests, with Lasius neglectus and its rapid spread through Europe and Asia as the most recent example of a pest ant that may become a global problem. Here, we present the first integrated study on behavior, morphology, population genetics, chemical recognition and parasite load of L. neglectus and its non-invasive sister species L. turcicus. We find that L. neglectus expresses the same supercolonial syndrome as other invasive ants, a social system that is characterized by mating without dispersal and large networks of cooperating nests rather than smaller mutually hostile colonies. We conclude that the invasive success of L. neglectus relies on a combination of parasite-release following introduction and pre-adaptations in mating system, body-size, queen number and recognition efficiency that evolved long before introduction. Our results challenge the notion that supercolonial organization is an inevitable consequence of low genetic variation for chemical recognition cues in small invasive founder populations. We infer that low variation and limited volatility in cuticular hydrocarbon profiles already existed in the native range in combination with low dispersal and a highly viscous population structure. Human transport to relatively disturbed urban areas thus became the decisive factor to induce parasite release, a well established general promoter of invasiveness in non-social animals and plants, but understudied in invasive social insects.