Explore the vast range of titles available.

Mimicry, where an organism (the mimic) convergently evolves traits resembling another (the model), is one of the most compelling phenomena in evolutionary biology. Despite ants frequently serving as models for Batesian mimics in other arthropod taxa, mimicry among ants is still underexplored. Rapid mimetic adaptations may superficially suggest a pathway to speciation; therefore, a thorough exploration of the phenomenon requires multivariate analyses. Consequently, we collected morphometric data from Colobopsis samples across the Mediterranean Basin and the Caucasus, documented color patterns of mimics and local models, and performed unsupervised multivariate analyses to examine evolutionary dynamics in the Mediterranean Colobopsis mimicry system. Our central questions were whether adaptive color changes in regional mimic populations reflect distinct evolutionary lineages leading to speciation or represent intraspecific responses to local environmental pressures, that is, adjustment to locally available models. We sought morphometric discontinuities in morphospace that might indicate the existence of distinct lineages among mimic populations with different color schemes. Biogeographic analyses show that Colobopsis imitans Schifani et al., 2022 replaces Colobopsis truncata (Spinola, 1808) throughout southern Europe and displays remarkably versatile region‐specific mimetic visual adaptations to local model species—hence the title analogy; this species is a true chameleon, in a biogeographical sense. Our research presents a scenario where mimicry‐driven microevolutionary adaptations can produce significant phenotypic diversity without leading to speciation. We collected morphometric data from Colobopsis samples across the Mediterranean Basin and the Caucasus, documented color patterns of these mimics and their local models, and performed unsupervised multivariate analyses. Morphometric data suggest a scenario where mimicry‐driven microevolutionary adaptations can produce significant phenotypic diversity without leading to speciation. Biogeographic analyses show that Colobopsis imitans displays remarkably versatile region‐specific mimetic visual adaptations to local model species.

The Mediterranean, a global hotspot for rare ant species, hosts a significant representation of the global diversity of the mainly Holarctic ant genus Temnothorax . However, several groups still require significant taxonomic efforts. The taxonomy of the T. luteus complex species was revised in 2014 when morphometrics allowed distinguishing two valid species and two synonyms out of four taxa that had been originally described from France. The two species recognized since then are T. luteus , distributed from Iberia to the Alps, and the largely sympatric but much more xerothermophilic T. racovitzai . In Italy, only a few records of the complex were ever published, and the identity of the Italian population was never thoroughly assessed. We combined morphometrics with phylogenomic data to assess the identity of the T. luteus populations that spanned from Sicily to the Italian Alps and discovered that all Italian samples belong to a new cryptic species, which we describe as T. apenninicus sp. nov. whose glacial refugium was probably in the southern Apennines.

[This corrects the article DOI: 10.1371/journal.pone.0308712.].

Morphometric research is being applied to a growing number and variety of organisms. Discoveries achieved via morphometric approaches are often considered highly transferable, in contrast to the tacit and idiosyncratic interpretation of discrete character states. The reliability of morphometric workflows in insect systematics has never been a subject of focused research, but such studies are sorely needed. In this paper, we assess the reproducibility of morphometric studies of ants where the mode of data collection is a shared routine. We compared datasets generated by eleven independent gaugers, that is, collaborators, who measured 21 continuous morphometric traits on the same pool of individuals according to the same protocol. The gaugers possessed a wide range of morphometric skills, had varying expertise among insect groups, and differed in their facility with measuring equipment. We used intraclass correlation coefficients (ICC) to calculate repeatability and reproducibility values (i.e., intra‐ and intergauger agreements), and we performed a multivariate permutational multivariate analysis of variance (PERMANOVA) using the Morosita index of dissimilarity with 9,999 iterations. The calculated average measure of intraclass correlation coefficients of different gaugers ranged from R = 0.784 to R = 0.9897 and a significant correlation was found between the repeatability and the morphometric skills of gaugers (p = 0.016). There was no significant association with the magnification of the equipment in the case of these rather small ants. The intergauger agreement, that is the reproducibility, varied between R = 0.872 and R = 0.471 (mean R = 0.690), but all gaugers arrived at the same two‐species conclusion. A PERMANOVA test revealed no significant gauger effect on species identity (R2 = 0.69, p = 0.58). Our findings show that morphometric studies are reproducible when observers follow the standard protocol; hence, morphometric findings are widely transferable and will remain a valuable data source for alpha taxonomy. This paper reveals that morphometric findings are reliable and widely transferable in insect research and can represent a valuable data source in the field of ecological and evolutionary studies. The manuscript can also help to educate readers on important issues regarding measurements and measurement error. This is especially important in the field of ecology and systematics today because there is a general lack of formal training in these important concepts in the 21st century biological science curriculum.

The high level of morphological crypsis of the hyper-diverse Palearctic Tetramorium caespitum group have challenged taxonomists for decades. Within this group, Wagner et al. (2017) offered a multidisciplinary solution for the delimitation of ten European species of the Tetramorium caespitum complex. Anatolia, harboring a high level of endemism in ants, has never been subject of focus research within this genus. In this study, the Tetramorium caespitum complex diversity in Anatolia and the Caucasus region was investigated by examining 191 nest-samples using an in-depth integrative-taxonomic approach. Quantitative morphometric and microsatellite data of 505 and 133 workers, respectively, and genital-morphology data of 33 nests were collected. Unsupervised analyses provided independent species-hypotheses based on the morphological and molecular disciplines. Based on the final species-hypotheses, we confirm T. caespitum (Linnaeus, 1758), T. hungaricum Röszler, 1935, T. indocile Santschi, 1927, T. caucasicum Wagner et al., 2017, T. impurum (Foerster, 1850), T. immigrans Santschi, 1927, and T. flavidulum Santschi, 1910 as valid species of the T. caespitum complex occurring in Anatolia. A lectotype of T. flavidulum was designated. The host of the temporary social-parasitic species Tetramorium aspina Wagner et al., 2018 is T. caucasicum instead of T. immigrans – as it was suggested before. An identification key to species complexes of the T. caespitum group and to workers of the species of the T. caespitum complex in Anatolia is provided. Every cluster we identified could be linked to described species and the region’s species-composition is similar to those of the Balkans and Central Europe.

Ant nests’ relatively stable and long-lasting microhabitats present ideal living conditions for many uni- and multicellular organisms, whose relationships range from mutualistic to parasitic. Messor harvester ants inhabit arid and semi-arid open areas where their colonies consist of large numbers of individuals. Due to the high number of other organisms associated with harvester ants, their nests can be defined as islands for unique biota. Despite significant progress in research on ant-associated fungi in Europe, little is still known about the recently described ectoparasitic fungus Rickia lenoirii Santamaria, 2015 (Laboulbeniales), found on two species of ants of the genus Messor. Here we report for the first time the occurrence of the ectoparasitic ant-associated fungus R. lenoirii from three countries (Albania, Bulgaria, and continental Greece) and multiple localities in the Balkans. The fungus was detected on four ant host species—Messor structor (Latreille, 1798), M. wasmanni Krausse, 1910, M. hellenius Agosti & Collingwood, 1987, and M. mcarthuri Steiner et al., 2018 with the latter two representing new host records. Furthermore, spores of the widespread endoparasitic fungus of ants, Myrmicinosporidium durum Hölldobler, 1933 (Blastocladiomycota), were reported for the first time in Messor structor (Bulgaria). Images of the ant-associated Rickia lenoirii taken with a scanning electron microscope, a comparison with R. wasmannii, and a distribution map are also presented.

The ant genus Temnothorax is one of the most diverse in the Palearctic region, comprising several species with different life histories and uncertain taxonomic backgrounds. Socially parasitic Temnothorax ant species were typically described decades ago, primarily based on traditional morphological traits. In some aspects, these species have come back into the spotlight in recent years, necessitating a comprehensive taxonomic revision of the species of the genus. In this paper, we present a quantitative morphology-based taxonomic revision of the Temnothorax corsicus species group (formerly called Myrmoxenus genus) based on the analysis of 20 continuous morphometric traits collected from 394 worker and 19 traits from 473 gyne individuals belonging to 240 samples. Based on morphometric analyses, we propose junior synonymy for Temnothorax tamarae (Arnol’di, 1968) under T . ravouxi (André, 1896), and T . microcellatus (Soudek, 1925) is revived and is considered a senior synonym of T . menozzii (Finzi, 1924). Detailed descriptions, measurements, distribution, and host usage of all ten species are given. Dichotomous keys to workers, known gynes, and photographs of all species are presented.

In the current revisionary work, the Temnothorax nylanderi species-group of myrmicine ants is characterized. Eighteen species belonging to this group in the Ponto-Mediterranean region are described or redefined based on an integrative approach that combines exploratory analyses of morphometric data and of a 658bp fragment of the mitochondrial gene for the cytochrome c oxidase subunit I (CO I). The species group is subdivided into five species complexes: T. angustifrons complex, T. lichtensteini complex, T. nylanderi complex, T. parvulus complex, T. sordidulus complex, and two species, T. angulinodis sp. n. and T. flavicornis (Emery, 1870) form their own lineages. We describe seven new species (T. angulinodis sp. n., T. angustifrons sp. n., T. ariadnae sp. n., T. helenae sp. n., T. lucidus sp. n., T. similis sp. n., T. subtilis sp. n.), raise T. tergestinus (FINZI, 1928) stat.n. to species level, and propose a new junior synonymy for T. saxonicus (SEIFERT, 1995) syn.n. (junior synonym of T. tergestinus). We describe the worker caste and provide high quality images and distributional maps for all eighteen species. Furthermore, we provide a decision tree as an alternative identification key that visually gives an overview of this species-group. We make the first application to Formicidae of the Semantic Phenotype approach that has been used in previous taxonomic revisions.

The mostly Holarctic genus Temnothorax (Hymenoptera, Formicidae) is the most diverse ant genus in temperate regions. The Mediterranean, a biodiversity hotspot of rare ant species, hosts over 150 Temnothorax taxa, including several short-range endemics. Over the last few years, phylogenomic reconstructions and integrative taxonomy have significantly improved the understanding of global Temnothorax diversity, but much taxonomic work is still needed in the Mediterranean region. Here, we present the integrative description of a new species of the genus, discovered in the central Mediterranean island of Sicily: Temnothorax siculus sp. n. is defined and compared to congeneric species integrating morphometrics and phylogenomics. It is a ground-nesting, lowland species, of which workers were regularly observed foraging on bushes and small trees. In the global phylogeny, covering all the main lineages of the region, it belongs to the Palearctic clade and is related to the tuberum and unifasciatus complexes. Morphological separation from other Sicilian Temnothorax species can generally be achieved on qualitative characters, but we also provide morphometric discriminant functions to separate it from T. apenninicus and especially T. unifasciatus. Temnothorax siculus has been rarely collected but appears to be widespread in Sicily, and may occur in neighboring regions.

Parasitism-generated negative effects on ant societies are multifaceted, implying individual and colony-level responses. Though laboratory based evidence shows that the sublethal fungus Rickia wasmannii is responsible for physiological and behavioral responses that may negatively affect individual workers’ resilience and life expectancy in Myrmica ant workers, colony-level stress response to this parasite is largely unknown. Here, we focus on understanding of a long-term, colony-level effect of Rickia infection on Myrmica scabrinodis ant populations by tracking trait size-based changes. We collected worker specimens from infected and uninfected colonies from the same population in order to: (1) compare body size in response to parasitism, (2) assess the extent to which possible changes in size are associated with the severity of infection, and (3) investigate shifts in body size in response to infection over time by testing correlation of workers’ ages and sizes. We found that workers from infected colonies were significantly smaller than their healthy congeners, but neither infection level nor the age of the workers showed significant correlation with the size in infected colonies. Decreasing body sizes in infected colonies can be ascribed to workers’ mediated effect toward developing larvae, which are unable to attain the average body size before they pupate.