Staphylinidae Research Articles

Seasonal dynamics of dominant species of soil predators (Coleoptera: Carabidae, Staphylinidae) in agrolandscapes and their potential gluttony

We studied the seasonal change in the number of dominant species of predatory beetles on vegetable crops and determined their potential gluttony. A total of 1,472 beetles were collected, belonging to 22 species of ground beetles (Carabidae) and 27 species of rove beetles (Staphylinidae). The dominant species are: Harpalus rufipes (De Geer, 1774) (17.6% dominance), Amara fulva (De Geer) (13.28%), Bembidion properans (Stephens, 1828) (10.39%), Trechus quadristriatus (Schrank, 1781) (6.20%), Calathus melanocephalus (Linnaeus, 1758) (5.39%), Poecilus cupreus Linnaeus, 1758 (5.3%), Bembidion femoratum Sturm, 1825 (5.10%), Aleochara bilineata, (Gyllenhaal, 1810) (17.6%), Aloconota gregagia (Erichson, 1839) (10.21%), Amischa analis (Gravenhorst, 1802) (6.01%), Amischa bifoveotata (Mannerheim, 1830) (5.41%). During the season, there is a change in dominant species. At the beginning of the season, smaller species dominate, while larger species dominate in the second half of the plant vegetation. The maximum number of predators are observed in June and August. The periods of the maximum abundance of ground beetles and rove beetles do not coincide in time, which is the evolutionary adaptation of two groups of predators that coexist. In laboratory experiments, when pest eggs were offered as food, Aleochara bilineata and Bembidion femoratum were the most voracious. Larger predator species showed high voracity when larvae of flies were offered as food.

Total-evidence analysis resolves the phylogenetic position of an enigmatic group of Paederinae rove beetles (Coleoptera: Staphylinidae)

Paederinae is one of the most diverse subfamilies among rove beetles, yet their evolutionary history remains poorly understood. This is attributed to the limited number of phylogenetic studies, which either sought answers at a shallower taxonomic level or included limited taxon sampling. Especially problematic is the position of the rare Neotropical tribe Cylindroxystini, morphologically one of the most puzzling groups of Paederinae. The phylogenetic position of this group within Paederinae was never understood, though its rank in the classification has already been shifted twice. We assembled molecular and morphological data matrices sampled from all currently recognized Paederinae subtribes, including both genera of Cylindroxystini, and used these data to estimate phylogenetic relationships using Bayesian inference. A total of 123 morphological characters and 4,631 bp of nuclear (28S, TP, Wg, CADA, CADC, ArgK) and mitochondrial (COI) sequences were analyzed for 76 taxa. The current tribe Cylindroxystini was resolved as a monophylum within the tribe Lathrobiini as sister to the genus Pseudolathra, and together they are sister to the so-called ‘Medonina and allied taxa’ clade. Based on these results, we downgraded Cylindroxystini back to the subtribal level, Cylindroxystina status reinstated, now with a known sister group. The resulting phylogeny is the largest of the subfamily Paederinae to date and lays the foundation for establishing a natural classification of the group.

An Integrative Taxonomic Review of the Quedius erythrogaster Mannerheim Species Group in North America (Coleoptera: Staphylinidae: Quediini)

Like many other members of the Microsaurus Dejean lineage of Quedius Stephens (Staphylinidae: Staphylininae: Quediini), rove beetles of the erythrogaster species group are facultatively or obligately associated with microhabitats within the nests of insects, mammals and, possibly, tree cavity-nesting birds. Generally, these cryptic and difficult to access microhabitats have been poorly surveyed in North America compared to Central Europe. This has resulted in limited material for taxonomists and several species likely remain to be discovered. Here we review species concepts in the erythrogaster group using newly available Nearctic material, including some extensive samples from mammal burrows. Using evidence from both morphological and CO1 barcode data, we propose the treatment of eight species, including four new species: Quedius alesi Brunke, new species, Quedius miltoni Brunke, new species, Quedius pinetis Brunke, new species, and Quedius praticola Brunke, new species. A phylogenetic analysis of the molecular data resolved two major clades within the erythrogaster group, the erythrogaster and compransor complexes. It also corroborated morphological evidence that Palearctic myrmecophile Quedius brevis Erichson belongs to the erythrogaster group and suggests that other Palearctic species could belong here upon further examination.

Horn scaling relationships in three species of Bledius Leach 1819 (Insecta: Coleoptera: Staphylinidae) show no indication of fitting non-linear allometric models

ABSTRACT The males of some species of the rove beetle genus Bledius Leach (1819) have a pronounced horn protruding from the anterior margin of the pronotum. The horn function is not known, however in many other horn-bearing beetles, these structures are implicated in male-male combat over females. In this study, scaling relationships are investigated for three species; B. spectabilis Kraatz, 1857, B. frisius Lohse, 1978 and B. tricornis (Herbst, 1784). Based on data collected from museum specimens, we fitted and compared different allometric models on pronotal width versus horn length in each species. A simple linear allometric model best describes the scaling relationship of horns in all three species. The horn allometry in the three Bledius species do not accordingly follow a ‘switch point’ model or a curved allometric relationship, models that are commonly reported to explain the scaling relationship of horns in many other beetle species. We therefore found no evidence of male dimorphism (minor/major phenotypes) in the species examined. The potential function of the horn in Bledius is discussed in light of similar studies.

Forest cover and heterogeneous pastures shape the diversity of predatory rove beetles in tropical riparian habitats

In tropical landscapes, forest remnants have been reduced to narrow strips of vegetation along rivers and streams surrounded by agricultural land that affects biodiversity, depending on the habitat and landscape characteristics. To assess the effect of riparian forest loss on the diversity of Staphylininae predatory rove beetles, we considered two habitat conditions (river sites with riparian vegetation and sites with heterogeneous pastures) within two micro-basin types (with >70% and <40% forest cover) in a tropical montane cloud forest landscape, Mexico. Beetles were collected using baited pitfall traps during the rainy season of 2014. No differences were found between micro-basin types and, although species richness (0D) was similar between habitat conditions, when the diversity of common (1D) and dominant (2D) species was considered, sites with heterogeneous pastures were almost twice as diverse as those with riparian vegetation. All diversity measurements were greater in sites with heterogeneous pastures of either micro-basin type. Air temperature and canopy cover were the environmental variables that best explained the variation in beetle species composition. The greatest environmental differences related to species composition were detected between habitat conditions and were more evident in sites with heterogeneous pastures and low forest cover in the surroundings. The results suggest that replacing riparian vegetation with heterogeneous pastures, within micro-basins that lost between 30% and 60% of their forest cover, does not significantly reduce the diversity of predatory rove beetle but rather modifies the beetle composition. Effective formulation of management strategies to mitigate the impact of land use modification therefore requires an understanding of the interaction between vegetation remnants and landscape characteristics.

Rove beetles (Coleoptera, Staphylinidae) from the Carpathian Biosphere Reserve in collections of State Museum of Natural History (Lviv, Ukraine)

The collection of the rove beetles (Coleoptera, Staphylinidae) in State Museum of Natural History (Lviv), National Academy of Sciences of Ukraine is one of the richest and most famous collections of Ukraine. A great part of this collection consists of dry mounted specimens (about 5000) including about 700 species. This material is partly mounted, reordered, and catalogued. In this paper, we present a checklist of these specimens collected by several generations of entomologists in the 20-21th centuries from the territory and surrounding areas of the Carpathian Biosphere Reserve (according to the labels). In general, there are 287 Staphylinidae specimens of 24 species of 16 genera and 6 subfamily (Aleocharinae – 8 species, Omaliinae – 2 species, Oxytelinae – 1 species, Staphylininae – 11 species, Tachyporinae – 2 species). Leptusa flavicornis Brancsik, 1874 is recorded in Ukraine for the first time.

Soil invertebrates occurrences in European North-East of Russia.

BackgroundThe European North-East of Russia is the territory which includes the Nenets Autonomous District, represented by the East European tundra (from Kanin Peninsula to Vaigach Island), Komi Republic with its taiga ecosystems and the Urals (Northern, SubPolar and Polar). Over 20 years of systematic studies of soil fauna in the studied region has resulted in a huge amount of data being accumulated that can be analysed from different positions. Considering that the representation of Russian soil biota data, especially from European North-East of Russia in the GBIF database is not large, our data are of great interest to the scientific world community. The accumulation of such data will solve questions on national and global scales using large arrays.This study produced a dataset containing information on occurrences on soil invertebrates (Lumbricidae, Chilopoda, Diplopda, Collembola, Elateridae and Staphylinidae) in the European North-East of Russia. The dataset summarises occurrences noted in natural and disturbed forests, tundra and mountain ecosystems.New informationData from 196 geo-referenced localities of European North-East of Russia (tundra, taiga and mountains ecosystems) have been collated. A total of 5412 occurrences are included in the resource. The current project surveys 13 species of earthworms, 20 species of millipedes, 246 species of springtails, 446 species of rove beetles and 60 species of click beetles. The diversity of soil invertebrates in the European North-East of Russia has not been fully explored and further exploration will lead to more taxa.

Local and Landscape Effects on Carrion-Associated Rove Beetle (Coleoptera: Staphylinidae) Communities in German Forests.

Simple SummaryIncreasing forest management practices by humans are threatening inherent insect biodiversity and thus important ecosystem services provided by them. One insect group which reacts sensitively to habitat changes are the rove beetles contributing to the maintenance of an undisturbed insect succession during decomposition by mainly hunting fly maggots. However, little is known about carrion-associated rove beetles due to poor taxonomic knowledge. In our study, we unveiled the human-induced and environmental drivers that modify rove beetle communities on vertebrate cadavers. At German forest sites selected by a gradient of management intensity, we contributed to the understanding of the rove beetle-mediated decomposition process. One main result is that an increasing human impact in forests changes rove beetle communities by promoting generalist and more open-habitat species coping with low structural heterogeneity, whereas species like Philonthus decorus get lost. Our results are not solely important for carrion ecological, but also for forensic entomological assessments on crime scenes, e.g., postmortem body relocation, because little information is available until now about rove beetles as one of the most important insect groups on bodies.Intensification of anthropogenic land use is a major threat to biodiversity and thus to essential ecosystem services provided by insects. Rove beetles (Coleoptera: Staphylinidae), which react sensitively to habitat changes, are species-rich colonizers of vertebrate cadavers and contribute to the important ecosystem service of carrion decomposition. The unveiling of anthropogenic and environmental drivers that modify carrion-associated rove beetle communities should improve our understanding of the plasticity of cadaver decay. We report the presence of 80 rove beetle species on 65 decomposing piglet cadavers at forest sites characterized by a gradient of management intensity across three geographic regions in Germany. Local and landscape drivers were revealed that shape beetle abundance, diversity, and community composition. Forest management and regions affect rove beetle abundance, whereas diversity is influenced by local habitat parameters (soil pH, litter cover) and regions. The community composition of rove beetles changes with management intensification by promoting generalist species. Regarding single species, Philonthus decorus and Anotylus mutator are linked to unmanaged forests and Ontholestes tessellatus to highly used forest stands. The spatial information provided about carrion-associated rove beetle communities in German forests is not only of carrion-ecological but also of forensic entomological interest.

Rove Beetles (Coleoptera, Staphylinidae) under the Conditions of Anthropogenic Agrolandscape Transformation in Northwestern Russia

As many as 147 species of rove beetles (Coleoptera, Staphylinidae) were found in the model agricultural landscape in Northwestern Russia. Cluster analysis showed that Staphylinidae complexes in cultivated lands were different from those in adjacent habitats: field margins, forest edges, and natural meadows. Rove beetles had higher species diversity in the agrocenoses of perennial grasses (clover, timothy grass), as compared with those subject to severe anthropogenic transformation (potatoes, grain crops, annual herbs).

Flight activity of rove beetles (Coleoptera: Staphylinidae) in the agricultural landscape in the Leningrad Region

Flight activity of rove beetles (Coleoptera: Staphylinidae) in the agricultural landscape in the Leningrad Region

Ground-Dwelling Invertebrate Abundance Positively Related to Volume of Logging Residues in the Southern Appalachians, USA

Invertebrates, especially those dependent on woody debris for a portion of their life cycle, may be greatly impacted by the amount of downed wood retained following timber harvests. To document relationships between invertebrates and logging residues, we sampled invertebrates with pitfall traps placed near or far from woody debris in 10 recently (2013–2015) harvested sites in western North Carolina with varying levels of woody debris retention. We measured the groundcover and microclimate at each trap and estimated site-level woody debris volume. We modeled predictors (e.g., site-level woody debris volume, percent woody debris cover at the trap site, site type) of captures of spiders (Araneae), harvestmen (Opiliones), centipedes/millipedes (Chilopoda/Diplopoda), ground beetles (Carabidae), rove beetles (Staphylinidae), other beetles, ants (Formicidae), grasshoppers (Acrididae/Tetrigidae), crickets (Gryllidae), and cave crickets (Rhaphidophoridae). In addition, we modeled ant occurrence at a finer taxonomic resolution, including red imported fire ants (Solenopsis invicta Buren) and 13 other genera/species. Forest type, whether hardwood or white pine (Pinus strobus L.) overstory preharvest, was a predictor of invertebrate response for 21 of 24 taxonomic analyses. Invertebrate captures or the occurrence probability of ants increased with increasing site-level woody debris volume for 13 of the 24 taxa examined and increased with increasing coarse woody debris (CWD; diameter ≥ 10 cm) cover at the trap level for seven of 24 taxa examined. Our results indicate that woody debris in harvested sites is important for the conservation of a majority of the taxa we studied, which is likely because of the unique microclimate offered near/under woody debris. Stand-scale factors typically were more important predictors of invertebrate response than trap-level cover of woody debris. We recommend implementing sustainability strategies (e.g., Biomass Harvesting Guidelines) to retain woody debris scattered across harvested sites to aid in the conservation of invertebrates.

Fifteen new species of Sathytes Westwood from China (Coleoptera, Staphylinidae, Pselaphinae), with an updated checklist of world species

The Chinese fauna of the pselaphine genus Sathytes Westwood (Batrisitae: Batrisini) currently includes 20 species. In this paper, 15 new species from various provinces of the country are described: S. alpicola sp. nov. (Xizang), S. australis sp. nov. (Guangdong, Guangxi), S. chayuensis sp. nov. (Xizang), S. chengzhifeii sp. nov. (Yunnan), S. huapingensis sp. nov. (Guangxi), S. linzhiensis sp. nov. (Xizang), S. maoershanus sp. nov. (Guangxi), S. nujiangensis sp. nov. (Yunnan), S. panzhaohuii sp. nov. (Xizang), S. shennong sp. nov. (Hubei), S. tianquanus sp. nov. (Sichuan), S. transversus sp. nov. (Xizang), S. valentulus sp. nov. (Guangxi), S. xingdoumontis sp. nov. (Hubei) and S. xizangensis sp. nov. (Xizang). New collection records are provided for S. longitrabis Yin &amp; Li, 2012, S. tangliangi Yin &amp; Li, 2012 and S. yunnanicus Yin &amp; Li, 2012. Maps showing the distribution of the genus in China, and an updated checklist of the world species are provided.

Rove beetles of the subfamily Aleocharinae (Coleoptera: Staphylinidae) from the Hutsulshchyna National Nature Park

This work is the first attempt to make up an inventory of the fauna of rove beetles in the Hutsulshchyna National Natural Park (Ukraine, Ivano-Frankivsk Oblast), which was created in 2002 and has an area of 32,271 hectares. The modern territory of the park has never been the object of special scientific research on the fauna of rove beetles of the Aleocharinae subfamily. As a result, information about the finds of representatives of the Aleocharinae subfamily has been obtained from the study of the largest collection of rove beetles in Ukraine, which contains both modern collections and collections of the late 19th and early 20th centuries. The collection was formed by Marian-Aloiz Lomnitski and was further developed and replenished with collections from different parts of Ukraine and the world by several generations of Ukrainian and European entomologists. For the moment, the collection is kept in the funds of the State Museum of Natural History of the National Academy of Sciences of Ukraine and contains more than 1,500 specimens, which belong to more than 300 species and are of great historical and scientific value. As a result of the conducted studies, 30 species belonging to 18 genera are reported for the first time for the fauna of the Hutsulshchyna National Nature Park, of which 4 species (Atheta corvina (Thomson, 1856), Schistoglossa viduata (Erichson, 1837), Leptusa puellaris puellaris (C. Hampe, 1863), Silusa rubra (Erichson, 1839)) are reported for the first time for the territory of Ukraine. The species and specimens (with references, data of their distribution in Europe, as well as substrate and biotope preferences of adults) are listed. The obtained data will later on provide an opportunity to expand the understanding of the distribution of species – specifically for faunal research, as well as for biogeographic modelling.

A remarkable new species of the rove beetle genus Anthobium Leach, 1819 from Eocene Baltic amber (Coleoptera, Staphylinidae, Omaliinae).

An unusual new omaliine species, Anthobium alekseevisp. nov., is described and illustrated from Eocene Baltic amber, tentatively placed in the megadiverse genus Anthobium Leach, 1819. A new monotypic species-group is established. The new species can easily be distinguished from other species of the genus by the larger body, shape of the subrectangular pronotum, and the presence of a median carina on the prosternum and large, subtriangular tooth on the inner side of each mesotibia, likely exhibiting a peculiar sexual dimorphism in the male. Based on the study of the specimen with support of microtomographic images, a brief comparative analysis of a new species with described extant species of Anthobium is provided.

Miniaturization re-establishes symmetry in the wing folding patterns of featherwing beetles

Most microinsects have feather-like bristled wings, a state known as ptiloptery, but featherwing beetles (family Ptiliidae) are unique among winged microinsects in their ability to fold such wings. An asymmetrical wing folding pattern, found also in the phylogenetically related rove beetles (Staphylinidae), was ancestral for Ptiliidae. Using scanning electron, confocal laser scanning, and optical microscopy, high-speed video recording, and 3D reconstruction, we analyze in detail the symmetrical wing folding pattern and the mechanism of the folding and unfolding of the wings in Acrotrichis sericans (Coleoptera: Ptiliidae) and show how some of the smaller featherwing beetles have reverted to strict symmetry in their wing folding. The wings are folded in three phases by bending along four lines (with the help of wing folding patches on the abdominal tergites) and locked under the closed elytra; they unfold passively in two phases, apparently with the help of the elasticity provided by resilin unevenly distributed in the wing and of convexities forming in the cross-sections of the unfolding wing, making it stiffer. The minimum duration of folding is 3.5 s; unfolding is much more rapid (minimum duration lowest recorded in beetles, 0.038 s). The folding ratio of A. sericans is 3.31 (without setae), which is greater than in any beetle in which it has been measured. The symmetrical wing folding pattern found in A. sericans and in all of the smallest ptiliids, in which ptiloptery is especially pronounced, is the only known example of symmetry re-established during miniaturization. This direction of evolution is remarkable because miniaturization is known to result in various asymmetries, while in this case miniaturization was accompanied by reversal to symmetry, probably associated with the evolution of ptiloptery. Our results on the pattern and mechanisms of wing folding and unfolding can be used in robotics for developing miniature biomimetic robots: the mechanisms of wing folding and unfolding in Ptiliidae present a challenge to engineers who currently work at designing ever smaller flying robots and may eventually produce miniature robots with foldable wings.

Ground-dwelling invertebrate diversity in domestic gardens along a rural-urban gradient: Landscape characteristics are more important than garden characteristics.

Urbanisation is increasing worldwide and is regarded a major driver of environmental change altering local species assemblages. Private domestic gardens contribute a significant share of total green area in cities, but their biodiversity has received relatively little attention. Previous studies mainly considered plants, flying invertebrates such as bees and butterflies, and birds. By using a multi-taxa approach focused on less mobile, ground-dwelling invertebrates, we examined the influence of local garden characteristics and landscape characteristics on species richness and abundance of gastropods, spiders, millipedes, woodlice, ants, ground beetles and rove beetles. We assume that most of the species of these groups are able to complete their entire life cycle within a single garden. We conducted field surveys in thirty-five domestic gardens along a rural-urban gradient in Basel, Switzerland. Considered together, the gardens examined harboured an impressive species richness, with a mean share of species of the corresponding groups known for Switzerland of 13.9%, ranging from 4.7% in ground beetles to 23.3% in woodlice. The overall high biodiversity is a result of complementary contributions of gardens harbouring distinct species assemblages. Indeed, at the garden level, species richness of different taxonomical groups were typically not inter-correlated. The exception was ant species richness, which was correlated with those of gastropods and spiders. Generalised linear models revealed that distance to the city centre is an important driver of species richness, abundance and composition of several groups, resulting in an altered species composition in gardens in the centre of the city. Local garden characteristics were important drivers of gastropod and ant species richness, and the abundance of spiders, millipedes and rove beetles. Our study shows that domestic gardens make a valuable contribution to regional biodiversity. Thus, domestic urban gardens constitute an important part of green infrastructure, which should be considered by urban planners.

Temperature Affects Chemical Defense in a Mite-Beetle Predator-Prey System

Temperature influences all biochemical and biophysiological processes within an organism. By extension, it also affects those ecological interactions that are mediated by gland-produced chemical compounds, such as reservoir-based chemical defense. Herein, we investigate how environmental temperature affects the regeneration of defensive secretions and influences the efficacy of chemical defense in a model predator-prey system: the oribatid mite Archegozetes longisetosus and the predaceous rove beetle Stenus juno. Through a combination of chemical analyses, non-linear regression modeling and theoretical simulations we show that the amount of defensive secretion responded to temperature in a unimodal optimum curve: the regeneration rate followed a positive, linear relationship up to 35°C, but rapidly broke down beyond this temperature ("tipping point" effect). Using functional response simulations, there is an initially positive dampening effect on the predation rate when regeneration is optimal, but at higher temperatures chemical defense does not counteract the previously described effects of elevated predatory pressure. In a larger context, our results demonstrate the need to integrate relevant environmental factors in predator-prey modeling approaches.

Predation Efficacy of Rove Beetle (Coleoptera: Staphylinidae) Adults in Response to Western Flower Thrips (Thysanoptera: Thripidae) Pupal Stage, Predator–Prey Ratio, and Searchable Area

AbstractThe rove beetle, Dalotia coriaria (Kraatz) (Coleoptera: Staphylinidae), is a soil-dwelling predator that preys upon insect pests residing in growing media. Minimal information exists addressing its predation on western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), below-ground life stages. Two laboratory experiments were conducted to assess the effects of western flower thrips pupal stage, predator–prey ratio, and searchable area on predation efficacy of rove beetle adults. In Experiment 1, predation was recorded in response to two thrips pupal stages (prepupae and pupae); three predator–prey ratios (1:5, 1:10, 1:15) and predator–prey ratios that were 2, 3, and 4 times greater. Experiment 2 was designed to assess predation in response to those predator–prey ratios along with searchable areas in 15.2- and 11.5-cm-diameter containers. Response was measured by capturing thrips adults on yellow sticky cards (YSC) as they emerged from pupation. The estimated mean probability of thrips adults captured on the cards was significantly higher for the 1:5 (61.1%) than for the 1:10 (39%) and 1:15 (34.7%) predator–prey ratios. The estimated mean probability of thrips adults captured on the cards for 2 times the predator–prey ratio (57%) was significantly higher than 3 times (37.2%) and 4 times (40.6%) the ratios. A significantly higher estimated mean probability of thrips adults was captured on the cards in the 15.2-cm-diameter containers than in the 11.5-cm-diameter containers. We conclude that a predator–prey ratio of 1:15 would result in fewer rove beetle adults needed to reduce western flower thrips prepupae/pupae stages and subsequent adult populations.

A case study on the outbreak of paederus dermatitis caused by rove beetles (coleoptera: Staphylinidae) in women´s hostels of eastern university, Sri Lanka

Disreputable outbreaks of Paederus dermatitis (PD) has been predominant in women´s hostels of Eastern University and its surroundings. This study was undertaken with the objectives of recommending precautions and treatment for students and local residents around the university from 2015-2019. Sampling was done by light traps and hand collection. Photographs of beetles and skin lesions were taken. Hostel surrounding was inspected to find out the breeding sites of beetles. Case review among affected students and staffs was carried out through face to face interview. Approximately, 145 students were principally affected on the exposed body parts of which 95% of students developed specific symptoms including erythema, edematous plaques with vesicles, micropustules and about 5 % of students reported no specific symptoms. PD was more prevalent during rainy seasons than drought months. The students in women´s hostels were more frequently affected than in men’s hostels. Population dynamics, seasonal variations, life history and behavior pattern of rove beetles should be thoroughly investigated prior to their control.

A new species of Edrabius Fauvel (Coleoptera, Staphylinidae, Staphylininae) from Uruguay.

A new rove beetle species, Edrabius uruguayensis Martínez-Villar, González-Vainer Tomasco, sp. nov., associated with the subterranean rodent Ctenomys rionegrensis in Uruguay, is described and illustrated. Photographs, scanning electron micrographs and drawings of the diagnostic character states are provided. The new species is compared with other species of the genus. Nucleotide sequence of the cytochrome oxidase subunit I was reported for the first time for the genus and phylogenetic reconstruction confirms their close relationship with the other genus used from the tribe Amblyopinini (Heterothops).