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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.

Social parasitic ants exploit the colonies of other ant species, either permanently or temporarily. The permanent parasites are amongst the rarest species of ants, although their hosts may be very common. Due to their rarity and often restricted distribution range, most of them are listed as vulnerable. Filling in the gaps in geographical and host ranges will advance our understanding of the social parasitic lifestyle's origin and evolution.This study reports the first records of the slave-makers Myrmoxenus algerianus (Cagniant, 1968) for Europe (Italy, Sicily) and M. ravouxi (André 1896) for Albania and the inquiline Anergates atratulus (Schenck, 1852) for Malta (Gozo). We also report new localities of Camponotus universitatis Forel, 1890 for Albania and Myrmoxenus gordiagini Ruzsky, 1902, M. kraussei (Emery, 1915) and Anergates atratulus for Bulgaria. Diversity, type of parasite-host relationships, host range, distribution and conservation of social parasitic ant species in Bulgaria are discussed. Although social parasitic ants are still understudied in Bulgaria, they represent 21% of the regional ant fauna.

This paper presents numeric morphology-based evidence on the broadly overlapping distribution of two thief ant species Solenopsis fugax (Latreille, 1798) and S. juliae (Arakelian, 1991) in the East European Pontic-Caspian region. The paper integrates two autonomous data collections and independent analyses performed by different researchers, using different equipment, considering different character combinations, and evaluating partially different samples. Five type series, the neotype series of Solenopsis fugax (Latreille 1798) and the type series of S. flavidula (Nylander, 1849), S. (Diplorhoptrum) fugax var. furtiva Santschi, 1934, S. (Diplorhoptrum) fugax var. pontica Santschi, 1934, S. (Diplorhoptrum) fugax var. scytica Santschi, 1934 were nested in one cluster and we propose the junior synonymy of the latter four taxa names with S. fugax. The other cluster contained only one type specimen of Solenopsis nitida (Dlussky & Radchenko, 1994) measured from AntWeb images. The naming of this cluster was based on both verbal statements and measurements of gynes given in the original description of Solenopsis juliae (Arakelian, 1991), which represents the oldest available name for this cluster. Hence, S. nitida is proposed as junior synonym of S. juliae. Solenopsis cypridis Santschi, 1934 is raised to species rank based on investigation of worker and gyne type specimens.

Citizen science is a valuable tool for monitoring different species, especially in cases concerning truly rare and difficult-to-detect species where time-consuming field studies are limited and long-term research projects are uncertain. To better understand the distribution of the rarely collected Cryptopone ochracea (Mayr, 1855) (Hymenoptera, Formicidae) in Hungary, we obtained the occurrence data with photos uploaded by non-professionals to the page of the largest Hungarian Facebook group dealing with ants and a citizen-science website dealing with biological data collection. In this article, we expand the known distribution of C. ochracea to include 46 new records from Hungary and one from Serbia. With two historical records, this previously undersampled species has now been found 48 times in Hungary. Our results prove that social media platforms and other websites for citizen science projects offer new and useful opportunities for researchers to involve non-professionals in scientific work and, thus, obtain large amounts of valuable data, even for understudied arthropod species.

In this paper, we provide numeric morphology-based evidence that the dark-colored Ponera coarctata var. lucida Emery, 1898, formerly considered a synonym of P. coarctata (Latreille, 1802), is conspecific with the lighter-colored Ponera testacea 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 Ponera coarctata var. 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 Ponera coarctata var. lucida Emery, 1898 with Ponera testacea 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.

Abstract Unprecedented technological advances in digitization and the steadily expanding open‐access digital repositories are yielding new opportunities to quickly and efficiently measure morphological traits without transportation and advanced/expensive microscope machinery. A prime example is the AntWeb.org database, which allows researchers from all over the world to study taxonomic, ecological, or evolutionary questions on the same ant specimens with ease. However, the reproducibility and reliability of morphometric data deduced from AntWeb compared to traditional microscope measurements has not yet been tested. Here, we compared 12 morphological traits of 46 Temnothorax ant specimens measured either directly by stereomicroscope on physical specimens or via the widely used open‐access software tpsDig utilizing AntWeb digital images. We employed a complex statistical framework to test several aspects of reproducibility and reliability between the methods. We estimated (i) the agreement between the measurement methods and (ii) the trait value dependence of the agreement, then (iii) compared the coefficients of variation produced by the different methods, and finally, (iv) tested for systematic bias between the methods in a mixed modeling‐based statistical framework. The stereomicroscope measurements were extremely precise. Our comparisons showed that agreement between the two methods was exceptionally high, without trait value dependence. Furthermore, the coefficients of variation did not differ between the methods. However, we found systematic bias in eight traits: apart from one trait where software measurements overestimated the microscopic measurements, the former underestimated the latter. Our results shed light on the fact that relying solely on the level of agreement between methods can be highly misleading. In our case, even though the software measurements predicted microscope measurements very well, replacing traditional microscope measurements with software measurements, and especially mixing data collected by the different methods, might result in erroneous conclusions. We provide guidance on the best way to utilize virtual specimens (2D z‐stacked images) as a source of morphometric data, emphasizing the method's limitations in certain fields and applications.

Abstract 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.

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 fauna of Sicily, the largest island in the Mediterranean basin, has been significantly overlooked over the time. Drafting a reliable Sicilian ant checklist requires extensive field surveys, a careful review of the literature and of museum specimens, as well as the taxonomic investigation of some problematic issues. As a part of these ongoing efforts, we present our results on the presence or absence of 25 species. By analyzing specimens collected during the last 35 years across the island and reviewing old records in the light of present-day taxonomy, we provide evidence of the presence of 9 species (Camponotus ruber, Lasius myops, L. platythorax, Plagiolepis schmitzii, Ponera testacea, Solenopsis orbula, Temnothorax clypeatus, T. nylanderi, and T. ravouxi), while suggesting the absence of 19 others (Camponotus ligniperda, C. sicheli, C. spissinodis, Formica lugubris, Lasius alienus, L. flavus, L. niger, L. paralienus, Messor minor, M. wasmanni, Monomorium monomorium, Myrmica scabrinodis, M. spinosior, Nylanderia sp. 2 sensu Schifani & Alicata 2018, Solenopsis fugax, Temnothorax luteus, T. tuberum, Tetramorium caespitum, and T. indocile). Similar studies are necessary across Italy, as a significant portion of the existing ant records is outdated due to the evolved taxonomic framework.

Background Madagascar is famous for its extremely rich biodiversity; the island harbors predominantly endemic and threatened communities meriting special attention from biodiversity scientists. Continuing ongoing efforts to inventory the Malagasy ant fauna, we revise the species currently placed in the myrmicine genus Aphaenogaster Mayr. One species described from Madagascar, Aphaenogaster friederichsi Forel, is synonymized with the Palearctic A. subterranea Latreille syn. nov. This species is considered neither native to Madagascar nor established in the region. This revision focuses on the balance of species in the A. swammerdami group which are all endemic to Madagascar. Methods The diversity of the Malagasy Aphaenogaster fauna was assessed via application of multiple lines of evidence involving quantitative morphometric, qualitative morphological, and DNA sequence data. (1) Morphometric investigation was based on hypothesis-free Nest Centroid clustering (NC-clustering) combined with PArtitioning based on Recursive Thresholding (PART) to estimate the number of morphological clusters and determine the most probable boundaries between them. This protocol provides a repeatable and testable approach to find patterns in continuous morphometric data. Species boundaries and the reliability of morphological clusters recognized by these exploratory analyses were tested via confirmatory Linear Discriminant Analysis (LDA). (2) Qualitative, external morphological characteristics (e.g., shape, coloration patterns, setae number) were subjectively evaluated in order to create a priori grouping hypotheses, and confirm and improve species delimitation. (3) Species delimitation analyses based on mitochondrial DNA sequences from cytochrome oxidase I (COI) gene fragments were carried out to test the putative species previously delimited by morphological and morphometric analyses. Results Five species can be inferred based on the integrated evaluation of multiple lines of evidence; of these, three are new to science: Aphaenogaster bressleri sp. n., A. gonacantha (Emery, 1899), A. makay sp. n., A. sahafina sp. n., and A. swammerdami Forel, 1886. In addition, three new synonymies were found for A. swammerdami Forel, 1886 (A. swammerdami clara Santschi, 1915 syn. n., A. swammerdami curta Forel, 1891 syn. n. and A. swammerdami spinipes Santschi, 1911 syn. n.). Descriptions and redefinitions for each taxon and an identification key for their worker castes using qualitative traits and morphometric data are given. Geographic maps depicting species distributions and biological information regarding nesting habits for the species are also provided.

Background: Parasites cause predictable alternative phenotypes of host individuals. Investigating these parasitogenic phenotypes may be essential in cases where parasitism is common or taxa is described based on a parasitized individual. Ignoring them could lead to erroneous conclusions in biodiversity-focused research, taxonomy, evolution, and ecology. However, to date, integrating alternative phenotypes into a set of wild-type individuals in morphometric analysis poses extraordinary challenges to experts. This paper presents an approach for reconstructing the putative healthy morphology of parasitized ants using algorithmic processing. Our concept enables the integration of alternative parasitogenic phenotypes in morphometric analyses. Methods: We tested the applicability of our strategy in a large pool of Cestoda-infected and healthy individuals of three Temnothorax ant species (T. nylanderi, T. sordidulus, and T. unifasciatus). We assessed the stability and convergence of morphological changes caused by parasitism across species. We used an artificial neural network-based multiclass classifier model to predict species based on morphological trait values and the presence of parasite infection. Results: Infection causes predictable morphological changes in each species, although these changes proved to be species-specific. Therefore, integrating alternative parasitogenic phenotypes in morphometric analyses can be achieved at the species level, and a prior species hypothesis is required. Conclusion: Despite the above limitation, the concept is appropriate. Beyond parasitogenic phenotypes, our approach can also integrate morphometric data of an array of alternative phenotypes (subcastes in social insects, alternative morphs in polyphenic species, and alternative sexes in sexually dimorphic species) whose integrability had not been resolved before.

The ant genus Camponotus (Mayr, 1861) is one of the most abundant and species rich ant genera in the Malagasy zoogeographical region. Although this group is commonly encountered, its taxonomy is far from complete. Here, we clarify the taxonomy of the Malagasy-endemic Camponotus subgenus Myrmopytia (Emery, 1920). Species delimitation was based on traditional morphological characters and multivariate morphometric analyses, including exploratory Nest Centroid clustering and confirmatory cross-validated Linear Discriminant Analysis. Four species are recognized: Camponotus imitator (Forel, 1891), Camponotus jodina sp. n., Camponotus karaha sp. n., and Camponotus longicollis sp. n. All four species appear to mimic co-occurring Aphaenogaster species. A diagnosis of the subgenus Myrmopytia, species descriptions, an identification key based on minor and major subcastes of workers, and the known geographical distribution of each species are provided.

Here we describe the diversity of the Malagasy Nesomyrmex brevicornis-group as the final installment of series describing the complete Malagasy Nesomyrmex fauna. In the current paper introduce the N. brevicornis-group, a newly outlined species group. We split this group from one of the four former groups, N. madecassus-group (sensu Csősz and Fisher 2015). The relatively small number of individuals available within the N. brevicornis-group relative to the large number of OTUs hampers the use of sophisticated statistical techniques to evaluate the morphological data. Instead, we assess the diversity of the N. brevicornis-group via a conventional morphology-based approach relying upon non-numeric characters (shape, sculpture, color etc.) recorded by simple eye inspection. Morphometric data are used as secondary data to confirm the most probable boundaries between species, but without employing statistical analyses. We rejected prior species hypotheses imposed by the primary approach if a non-overlapping range of a single index calculated from continuous numeric traits was found between two hypothesized species. Our methods render every species in this revisionary work separable via both salient features and morphometric traits. Our approach reveals the existence of nine morphologically distinct species, Nesomyrmex brevicornis sp. n., N. brunneus sp. n., N. cingulatus sp. n., N. edentates sp. n., N. flavigaster sp. n., N. longiceps sp. n., N. minutus sp. n., N. punctaticeps sp. n., and N. sellaris sp. n.. Geographic maps showing the distribution of each species are provided, along with an updated key to workers of Malagasy Nesomyrmex species groups that includes the newly outlined N. brevicornis-group.

Ants (Hymenoptera: Forimicidae) are exceedingly common in nature. They constitute a conspicuous part of the terrestrial animal biomass and are also considered common ecosystem engineers. Due to their key role in natural habitats, they are at the basis of any nature conservation policy. Thus, the first step in developing adequate conservation and management policies is to build a precise faunistic inventory. More than 16,000 valid ant species are registered worldwide, of which 126 are known to occur in Hungary. Thanks to the last decade’s efforts in the Hungarian myrmecological research, and because of the constantly changing taxonomy of several problematic ant genera, a new checklist of the Hungarian ants is presented here. The state of the Hungarian myrmecofauna is also discussed in the context of other European countries’ ant fauna. Six species (Formica lemani, Lasius nitidigaster, Tetramorium immigrans, T. staerckei, T. indocile and Temnothorax turcicus) have been reported for the first time in the Hungarian literature, nine taxon names were changed after systematic replacements, nomenclatorial act, or as a result of splitting formerly considered continuous populations into more taxa. Two species formerly believed to occur in Hungary are now excluded from the updated list. All names are nomenclaturally assessed, and complete synonymies applied in the Hungarian literature for a certain taxon are provided. Wherever it is not self-evident, comments are added, especially to explain replacements of taxon names. Finally, we present a brief descriptive comparison of the Hungarian myrmecofauna with the ant fauna of the surrounding countries. The current dataset is a result of ongoing work on inventorying the Hungarian ant fauna, therefore it is expected to change over time and will be updated once the ongoing taxonomic projects are completed.

The paper integrates two independent studies of numeric morphology-based alpha-taxonomy of the cryptic ant species Temnothorax crassispinus (Karavajev, 1926) and T. crasecundus sp. n. conducted by different investigators, using different equipment, considering different character combinations and evaluating different samples. Samples investigated included 603 individual workers from 203 nests – thereof 104 nest samples measured by Seifert and 99 by Csösz. The material originated from Europe, Asia Minor and Caucasia. There was a very strong interspecific overlap in any of the 29 shape characters recorded and subjective expert determination failed in many cases. Primary classification hypotheses were formed by the exploratory data analysis Nest Centroid (NC) clustering and corrected to final species hypotheses by an iterative linear discriminant analysis algorithm. The evaluation of Seifert’s and Csösz’s data sets arrived at fully congruent conclusions. NC-Ward and NC-K-means clustering disagreed from the final species hypothesis in only 1.9 and 1.9% of the samples in Seifert’s data set and by 1.1 and 2.1% in Csösz’s data set which is a strong argument for heterospecificity. The type series of T. crassispinus and T. crasecundus sp. n. were allocated to different clusters with p = 0.9851 and p = 0.9912 respectively. The type series of the junior synonym T. slavonicus (Seifert, 1995) was allocated to the T. crassispinus cluster with p = 0.9927. T. crasecundus sp. n. and T. crassispinus are parapatric species with a long contact zone stretching from the Peloponnisos peninsula across Bulgaria northeast to the southern Ukraine. There is no indication for occurrence of interspecifically mixed nests or intraspecific polymorphism. However, a significant reduction of interspecific morphological distance at sites with syntopic occurrence of both species indicates local hybridization. The results are discussed within the context of the Pragmatic Species Concept of Seifert (2014). The taxonomic description and a differential diagnosis of T. crasecundus sp. n. are given.

Background. Applying quantitative morphological approaches in systematics research is a promising way to discover cryptic biological diversity. Information obtained through twenty-first century science poses new challenges to taxonomy by offering the possibility of increased objectivity in independent and automated hypothesis formation. In recent years a number of promising new algorithmic approaches have been developed to recognize morphological diversity among insects based on multivariate morphometric analyses. These algorithms objectively delimit components in the data by automatically assigning objects into clusters. Method. In this paper, hypotheses on the diversity of the Malagasy Nesomyrmex angulatus group are formulated via a highly automated protocol involving a fusion of two algorithms, (1) Nest Centroid clustering (NC clustering) and (2) Partitioning Algorithm based on Recursive Thresholding (PART). Both algorithms assign samples into clusters, making the class assignment results of different algorithms readily inferable. The results were tested by confirmatory cross-validated Linear Discriminant Analysis (LOOCV-LDA). Results. Here we reveal the diversity of a unique and largely unexplored fragment of the Malagasy ant fauna using NC-PART-clustering on continuous morphological data, an approach that brings increased objectivity to taxonomy. We describe eight morphologically distinct species, including seven new species: Nesomyrmex angulatus (Mayr, 1862), N. bidentatus sp. n., N. clypeatus sp. n., N. devius sp. n., N. exiguus sp. n., N. fragilis sp. n., N. gracilis sp. n., and N. hirtellus sp. n.. An identification key for their worker castes using morphometric data is provided. Conclusions. Combining the dimensionality reduction feature of NC clustering with the assignment of samples into clusters by PART advances the automatization of morphometry-based alpha taxonomy.

Madagascar is one of the world's greatest biodiversity hotspots, meriting special attention from biodiversity scientists. It is an excellent testing ground for novel techniques in taxonomy that aim to increase classification objectivity and yield greater taxonomic resolving power. Here we reveal the diversity of a unique and largely unexplored fragment of the Malagasy ant fauna using an advanced combination of exploratory analyses on quantitative morphological data allowing for increased objectivity in taxonomic workflow. The diversity of the Nesomyrmex sikorai species-group was assessed via hypothesis-free nest-centroid-clustering combined with recursive partitioning to estimate the number of morphological clusters and determine the most probable boundaries between them. This combination of methods provides a highly automated and objective species delineation protocol based on continuous morphometric data. Delimitations of clusters recognized by these exploratory analyses were tested via confirmatory Linear Discriminant Analysis (LDA) and Multivariate Ratio Analysis (MRA). The final species hypotheses are corroborated by many qualitative characters, and the recognized species exhibit different spatial distributions and occupy different ecological regions. We describe and redescribe eight morphologically distinct species including six new species: Nesomyrmex excelsior sp. n., N. modestus sp. n., N. reticulatus sp. n., N. retusispinosus (Forel, 1892), N. rugosus sp. n., N. sikorai (Emery, 1896), N. striatus sp. n., and N. tamatavensis sp. n. An identification key for their worker castes using morphometric data is provided.

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.

Abstract 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.

It is commonly held that Central Europe harbours but a single harvester ant species, namely Messor structor. Recently discovered bionomic differences between two Central European populations, which may reflect interspecific variation, cast doubt on this assumption. In the present study we test alternative hypotheses - one versus two harvester ant species in Central Europe and adjacent regions - by investigating the genetic diversity of ants determined as M. structor or close to it ("M. cf. structor"). Sequences of the mitochondrial COI gene revealed two major lineages of different but partially overlapping geographic distributions, both occurring in Central Europe. The existence of a cryptic species within M. cf. structor is the most plausible interpretation, since the sequence divergence between the two major lineages equals those between M. capitatus, M. concolor and M. bouvieri. The phylogenetic analyses revealed a distinct substructuring for both of the detected major lineages and the possible existence of additional cryptic species.

Despite a large and multifaceted effort to understand the vast landscape of phenotypic data, their current form inhibits productive data analysis. The lack of a community-wide, consensus-based, human- and machine-interpretable language for describing phenotypes and their genomic and environmental contexts is perhaps the most pressing scientific bottleneck to integration across many key fields in biology, including genomics, systems biology, development, medicine, evolution, ecology, and systematics. Here we survey the current phenomics landscape, including data resources and handling, and the progress that has been made to accurately capture relevant data descriptions for phenotypes. We present an example of the kind of integration across domains that computable phenotypes would enable, and we call upon the broader biology community, publishers, and relevant funding agencies to support efforts to surmount today's data barriers and facilitate analytical reproducibility.