The earth-boring beetles, or Geotrupidae, are a distinct group within the order Coleoptera, with approximately 350 species described worldwide. In Georgia, only the subfamily Geotrupinae is represented, a fact that simplifies the taxonomic scope of this particular study. The entomofauna of Georgia has been studied for centuries, with one of the first lists of beetles in the Caucasus published by Radde in 1899. However, the most significant foundational work on Georgian earth-boring dung beetles was conducted by Yason Dzambazishvili, whose comprehensive data on their distribution in 1979 and 2000 remains a cornerstone for current research. Since those seminal works, new distributional data have emerged from public databases such as the Global Biodiversity Information Facility (GBIF) and the Georgian Biodiversity Database, as well as from social media platforms that have proven to be valuable tools for gathering citizen science data.

The methodology for this catalog involved a rigorous compilation of occurrence data from multiple sources, including the papers of Dzambazishvili and Japoshvili et al., various web-databases, and dry collections deposited in institutions such as the Agricultural University of Georgia and the Zoological Institute of Ilia State University. Additionally, previously unpublished original material collected under the Caucasus Barcode of Life (CaBOL) project was included to ensure the most up-to-date representation of species presence. For occurrence data lacking exact geographic coordinates, researchers geo-referenced sampling locations using Google Earth Pro with an estimated precision of 100 meters. Conservation statuses were evaluated using IUCN guidelines, with the area of occupancy (AOO) calculated based on a 10 km² grid cell count overlaid on the country’s territory, and the extent of occurrence (EOO) estimated specifically for Georgia.

Among the species cataloged, Geotrupes molestus stands out as a candidate for further investigation, currently listed as Data Deficient (DD) for the national red list. This species is generally distributed in the Caucasus and is known from Armenia and Turkey, but in Georgia, it has only been recorded from a single locality in the Samtskhe-Javakheti region at the Zekari pass. The limited data available suggests that while the species may occupy a larger area, current information is insufficient to assess its conservation status confidently. Field data from the Goderdzi Pass through the Javakheti Highland to the Armenian border is needed to better understand the distribution range of G. molestus in Georgia, highlighting the gaps in current knowledge regarding this particular taxon.

In contrast, Geotrupes mutator is evaluated as Least Concern (LC) for the national red list, reflecting its widespread distribution across Georgia. With an area of occupancy of 180 km² and an extent of occurrence of 31,370 km², this species is found in numerous localities, including Khevsha, Lisi Lake, and the highlands around Kazbegi. The population trend is not known, and no direct threats have been indicated, supporting its classification as a species of low conservation concern. Similarly, Geotrupes (stercorarius) olgae is also classified as Least Concern, with an even larger area of occupancy of 620 km² and an extent of occurrence of 56,893 km². This species is widespread and common throughout the country, with records from diverse habitats ranging from the surroundings of Paravani Lake to the high altitudes of the Svaneti region.

Geotrupes spiniger presents a more complex conservation picture, being classified as Data Deficient (DD) despite its broad global distribution in Europe and Western Asia. In Georgia, the species has been recorded in several locations, including Tbilisi, Pasanauri, and Mestia, but the area of occupancy is relatively small at 21.175 km², with an extent of occurrence of 180 km². The lack of comprehensive data prevents a confident evaluation of its status, and while no threats or population changes have been reported globally, local assessments remain uncertain. This highlights the importance of continued monitoring and data collection to accurately assess the conservation needs of species with fragmented or poorly documented distributions within the country.

Trypocopris caspius, formerly known as Geotrupes caucasicus, is evaluated as Least Concern (LC) for the national red list. This species is distributed across the Central Caucasus and is recorded in various parts of Georgia, including Guria, Imereti, and Adjara. With a large area of occupancy of 190 km² and an extent of occurrence of 47,299 km², and no known population declines or threatening factors, it is considered secure in its current range. The study also clarifies taxonomic issues, noting that G. caucasicus Weise, 1879, listed by Dzambazishvili, is now known as Trypocopris caspius, while other homonyms have never been reported from Georgia, ensuring clarity in the nomenclature used in the catalog.

The most concerning finding in the catalog is the status of Trypocopris inermis, which is evaluated as Vulnerable (VU) for the national red list. This species is endemic to the western part of the Greater Caucasus, and Georgian populations represent the southern margin of its distribution. With a relatively small area of occupancy of 70 km² and an extent of occurrence of 3,121 km², the species faces potential risks due to its limited range. The study suggests that additional studies are needed to delineate the southern border of its distribution, particularly in the Svaneti region, where its presence cannot be excluded. The endemic status of the species, combined with its marginal populations in Georgia, underscores the need for targeted conservation efforts to protect this unique component of the region’s biodiversity.

The catalog also notes the recent report of Odonteus armiger from Lagodekhi Protected Areas and south-western Georgia, based on citizen science data. However, these records require further confirmation, and no conservation status can be evaluated at any level of uncertainty. The study emphasizes that many places within Georgian territory remain unobserved for earth-boring beetles, indicating that the current catalog is a starting point rather than a complete picture. By providing updated distribution maps and conservation evaluations, this work serves as a vital resource for future research and conservation planning, ensuring that the intricate web of life in the Caucasus is better understood and protected for generations to come.

Subject of Research: Conservation status and distribution of Geotrupidae beetles in Georgia

Article Title: Catalog of Georgian Earth-boring dung beetles ( Coleoptera : Geotrupidae )

Article References: Japarashvili, S. (2023). Catalog of Georgian Earth-boring dung beetles (Coleoptera: Geotrupidae). Caucasiana, 2, 83-90. https://doi.org/10.3897/caucasiana.2.e96388

Image Credits: AI Generated

DOI: 10.3897/caucasiana.2.e96388

Keywords: Geotrupidae, dung beetles, Georgia, Caucasus, conservation status, IUCN Red List, entomology, biodiversity, distribution mapping, Coleoptera, Catalog, Georgian

One of the central technical challenges in building such a catalog is distinguishing genuine symbionts from organisms that merely co-occur with a host in a sampled environment. Metagenomic sequencing of a sponge, a coral, or a gut contents sample inevitably picks up transient organisms passing through, along with free-living cells attached to host surfaces only loosely. The curation process therefore relies on converging lines of evidence: consistent recovery of the same metagenome-assembled genome across multiple host samples, enrichment relative to surrounding environmental controls, presence of host-interaction genes such as adhesins, secretion systems, or ankyrin-repeat proteins, and in some cases single-cell or fluorescence-based confirmation of intracellular residence. When several of these signals align, confidence that a genome represents a true associate rises substantially, and the catalog can encode that confidence rather than presenting all entries as equivalent.

Metagenome-assembled genomes, or MAGs, form the backbone of most contemporary catalogs, and they come with well-understood caveats. Because assembly reconstructs genomes from mixed communities, strain variation within a species can cause contigs to be dropped or misjoined, and highly repetitive regions such as rRNA operons are frequently collapsed. Completeness and contamination estimates, typically derived from the presence of single-copy marker genes, provide a quality filter, but they are imperfect proxies. A genome flagged as ninety percent complete may still lack the very genes a researcher cares about, particularly if those genes sit on a plasmid or a mobile element with unusual composition. For symbionts, an additional complication arises from genome reduction: many obligate associates have shed repair pathways and regulatory machinery, producing small, AT-rich, fast-evolving genomes that assemble poorly and can be misbinned. The catalog’s inclusion criteria and quality tiers therefore carry real interpretive weight for downstream users.

The evolutionary significance of a dedicated symbiont catalog becomes clearest when considering genome reduction as a continuum. Facultative associates, which can survive outside the host, tend to retain large genomes with extensive metabolic flexibility. Obligate mutualists and parasites, by contrast, often show dramatic gene loss, sometimes retaining fewer than five hundred genes. Classic examples include aphid endosymbionts of the genus Buchnera, which supply essential amino acids to their insect hosts while having lost nearly all genes for independent life, and the hydrogenosome-bearing protist associates found in anaerobic environments. By placing newly recovered genomes along this continuum, the catalog allows comparative analyses that ask which functions are consistently retained when a lineage commits to symbiosis. Amino acid and vitamin biosynthesis pathways, ATP synthesis machinery, and cell envelope maintenance recur as the retained core across many independent lineages, a pattern that speaks to the shared metabolic logic of intimate association.

Horizontal gene transfer deserves particular attention in symbiotic systems. Symbionts frequently acquire genes directly relevant to their lifestyle, including carbohydrate-active enzymes for degrading host-derived glycans, iron-scavenging systems for competing within host tissues, and defense islands encoding restriction-modification systems or toxin-antitoxin pairs that protect against phages and competing microbes. Conversely, hosts sometimes acquire genes from their associates, a process documented in insects where bacterial genes have been incorporated into host genomes and repurposed. A structured catalog makes it possible to survey these transfers systematically, comparing gene content across symbionts from different hosts and environments to identify which acquisitions are widespread and which are lineage-specific innovations. Such surveys have repeatedly shown that symbiont genomes are hotspots for exchange relative to their free-living relatives, likely because the dense, structured populations within host tissues facilitate cell-to-cell contact.

The archaeal component of the catalog is especially valuable given how unevenly archaeal symbionts have been sampled. Archaea are often perceived as environmental organisms dominating oceans, sediments, and extreme habitats, yet several lineages are established associates of animals and protists. Methanogenic archaea in the human and ruminant gut, principally Methanobrevibacter species, are among the best characterized, contributing to hydrogen balance in fermentative communities and potentially influencing host caloric extraction from fiber. Anaerobic ciliates in the rumen and in termite guts harbor ecto- and endosymbiotic methanogens that consume hydrogen produced by the protist’s hydrogenosomes, a tripartite metabolic arrangement that has become a textbook example of syntrophy. Expanding the representation of these and other archaeal associates corrects a long-standing bacterial bias in symbiosis research and enables searches for archaeal-specific interaction mechanisms, such as archaeal surface layer proteins or methanogen-specific metabolite exchanges.

Cross-kingdom metabolic complementarity is one of the most striking themes to emerge from symbiont genomics generally. In many associations, the combined metabolic network of host and symbiont accomplishes transformations that neither partner can achieve alone. Deep-sea tube worms and their sulfur-oxidizing endosymbionts, corals and their dinoflagellate partners, legumes and nitrogen-fixing rhizobia, and ruminants and their fermentative microbiota all illustrate the principle, but bacterial-bacterial and archaeal-bacterial symbioses follow the same logic at finer scales. Syntrophic consortia in which one partner ferments organic matter and another consumes the resulting hydrogen or formate keep reactions thermodynamically favorable that would otherwise stall. Genomic evidence for these arrangements includes complementary pathway halves, shared electron shuttling mechanisms, and reciprocal gene loss that locks partners into obligate dependence. A catalog that indexes such associations provides the raw material for identifying new instances of these metabolic handshakes in underexplored hosts.

From a biotechnological standpoint, symbiont genomes are a rich but underexploited source of biosynthetic gene clusters. Insects, marine invertebrates, and plants all host associates that produce small molecules with documented or suspected roles in host defense, signaling, or competition. The association between certain beetles and actinobacterial symbionts that synthesize antimicrobial compounds protecting fungal gardens is a well-studied case, and marine invertebrates such as sponges and tunicates harbor bacterial phyla, including candidate phyla with no cultured representatives, whose biosynthetic potential is only now being inventoried. Polyketide synthase and nonribosomal peptide synthetase loci recovered from MAGs can be prioritized for heterologous expression, and the catalog’s host-association metadata helps researchers target environments where chemical mediation of the symbiosis is likely. Similar reasoning applies to enzymes: carbohydrate-active enzymes from gut symbionts inform industrial biomass conversion, and stress-protective proteins from extremophile associates have applications in stabilization of biomolecules.

Clinically and agriculturally, the catalog’s value lies in providing reference genomes against which disease-associated or performance-associated dysbioses can be interpreted. Human microbiome studies have shown that health effects often depend on specific strains rather than species-level presence, and having high-quality symbiont genomes with annotated interaction genes makes strain-level resolution more achievable. In livestock, methanogen abundance correlates with enteric methane emissions, and genomic characterization of rumen archaea supports mitigation strategies ranging from dietary intervention to vaccine design against methanogen surface antigens. In crop systems, beneficial root associates that fix nitrogen, solubilize phosphorus, or induce systemic resistance in the plant are of intense interest, and reference genomes accelerate the identification of traits that can be bred or engineered into synthetic communities.

Ecologically, the catalog enables a shift from case studies to global patterns. Symbiosis is increasingly recognized as a major driver of microbial evolution, with host-associated lineages diversifying in allopatry across host populations in a manner analogous to geographic isolation in free-living species. Comparing symbiont genomes across host species, geography, and environment allows tests of cospeciation, host switching, and symbiont replacement, questions that previously required decades of targeted sampling. The phylogenetic breadth captured in a large catalog also reveals how many times symbiosis has arisen independently within major bacterial and archaeal lineages, and whether transitions into host association are accompanied by predictable genomic changes. Early comparative work suggests that while genome reduction is common, the specific genes lost and retained vary with host type and transmission mode, with vertically transmitted symbionts showing the most extreme degradation and horizontally transmitted ones retaining larger genomes and more interaction machinery.

Methodologically, the catalog also serves as a benchmark for the field’s evolving standards. The transition from single isolate genomes to MAGs, single-amplified genomes, and now population-level pangenomes has raised questions about how to represent microbial diversity fairly. Symbionts add a further layer because the same organism may appear in a host-associated form and a free-living form with different gene content, and because intrahost population structure can be substantial. How the catalog handles these issues, through quality tiers, host metadata, and explicit provenance for each genome, will influence how future resources are designed. The emphasis on linking genomes to their ecological context rather than treating them as abstract sequences reflects a broader maturation of microbiome science, in which the unit of interest is not the genome alone but the genome in its functional setting.

Looking forward, the most productive uses of the catalog will likely combine its genomic content with independent data streams. Transcriptomic and proteomic measurements from host-associated communities can confirm which symbiont genes are actually expressed during interaction, metabolomics can validate predicted cross-feeding, and long-read sequencing can close the gaps that short-read assembly leaves in reduced symbiont genomes. Cultivation efforts guided by genomic predictions, using media designed around a symbiont’s inferred metabolic needs, remain essential for converting catalog entries into experimentally tractable organisms. As these layers accumulate, the catalog functions less as a static inventory and more as an index into a growing body of knowledge about how bacteria and archaea live in intimate association with other life, a mode of existence that, by all available evidence, is among the most common and most consequential on Earth.

Subject of Research: A genomic catalog of Earth’s bacterial and archaeal symbionts

Article Title: A genomic catalog of Earth’s bacterial and archaeal symbionts

Article References: Villada, J. C., Vasquez, Y. M., Szabó, G., Whittaker-Walker, E., Romero, M. F., Qin, S., Varghese, N., Eloe-Fadrosh, E. A., Kyrpides, N. C., SymGs data consortium, Stepanauskas, R., Francis, C. A., Cavicchioli, R., McMahon, K. T., Hallam, S., Liu, W.-T., Mock, T., Tiedje, J., Guo, J., … Schulz, F. (2026). A genomic catalog of Earth’s bacterial and archaeal symbionts. Nature Biotechnology. https://doi.org/10.1038/s41587-026-03213-1

Image Credits: AI Generated

DOI: 10.1038/s41587-026-03213-1

Keywords: genomic, catalog, Earth, bacterial, archaeal, symbionts, scientific research