Taxonomy in horses involves the classification and naming of horse species within the broader context of biological classification. This system organizes horses into hierarchical categories based on shared characteristics and evolutionary history. The domestic horse, Equus caballus, is classified within the family Equidae, which also includes zebras and donkeys. Taxonomic classification helps in understanding the evolutionary relationships and genetic diversity among different equine species. This page compiles peer-reviewed research studies and scholarly articles that explore the taxonomy of horses, including phylogenetic analyses, genetic studies, and the implications of taxonomic classification for conservation and breeding programs.
Kalmykov NP.Morphological features of the teeth were studied in the three-toed horse Hipparion tchicoicum from the Pliocene of Western Transbaikalia (Russia). Several diagnostic signs of the Chicoi hipparion were described for the first time to provide criteria for distinguishing the taxon among other fossils of three-toed horses and estimating their real diversity at the final stage of their distribution in Inner Asia.
Landry Z, Roloson MJ, Fraser D.The metapodials of extinct horses have long been regarded as one of the most useful skeletal elements to determine taxonomic identity. However, recent research on both extant and extinct horses has revealed the possibility for plasticity in metapodial morphology, leading to notable variability within taxa. This calls into question the reliability of metapodials in species identification, particularly for species identified from fragmentary remains. Here, we use ten measurements of metapodials from 203 specimens of four Pleistocene horse species from eastern Beringia to test whether there are s...
Sangal V, Goodfellow M, Jones AL, Sutcliffe IC.Opinion 106 of the Judicial Commission has clarified the nomenclature of the taxon variously named , ' and . As a consequence, we present here the genus name and that of its nomenclatural type species, comb. nov., for valid publication and propose the reclassification of four rhodococcal species as novel combinations in the genus, namely Guo et al. 2015 comb. nov., Kämpfer . 2014 comb. nov., Li . 2015 comb. nov. and Lee . 2019 comb. nov. In addition, we note that a clinical isolate, strain 86-07 (=W8901), likely represents an additional species within the genus . Nearly a century after ...
Aldayarov N, Tulobaev A, Salykov R, Jumabekova J, Kydyralieva B, Omurzakova N, Kurmanbekova G, Imanberdieva N, Usubaliev B, Borkoev B, Salieva K....In their centuries-old nomadic life, since their livestock was the backbone of their lives, the Kyrgyz people used a variety of wild medicinal plants for ethnoveterinary practices. However, the plants used for the treatment of livestock ailments never have been recorded, except rarely in local publications. In this study, we present the HSHR (homemade single species herbal remedy reports), their methods of preparation and application, and the livestock ailments for which these remedies were used. Objective: The collect data from the five different high-altitude valleys of the Kyrgyz Republic o...
Cirilli O, Pandolfi L, Rook L, Bernor RL.Evolution of the genus Equus has been a matter of long debate with a multitude of hypotheses. Currently, there is no consensus on either the taxonomic content nor phylogeny of Equus. Some hypotheses segregate Equus species into three genera, Plesippus, Allohippus and Equus. Also, the evolutionary role of European Pleistocene Equus stenonis in the origin of the zebra-ass clade has been debated. Studies based on skull, mandible and dental morphology suggest an evolutionary relationship between North American Pliocene E. simplicidens and European and African Pleistocene Equus. In this contributio...
Martin de Bustamante M, Gomez D, MacNicol J, Hamor R, Plummer C.The objective of this study was to describe and compare the fecal bacterial microbiota of horses with equine recurrent uveitis (ERU) and healthy horses using next-generation sequencing techniques. Fecal samples were collected from 15 client-owned horses previously diagnosed with ERU on complete ophthalmic examination. For each fecal sample obtained from a horse with ERU, a sample was collected from an environmentally matched healthy control with no evidence of ocular disease. The Illumina MiSeq sequencer was used for high-throughput sequencing of the V4 region of the 16S rRNA gene. The relativ...
Vershinina AO, Kapp JD, Baryshnikov GF, Shapiro B.Museum collections are essential for reconstructing and understanding past biodiversity. Many museum specimens are, however, challenging to identify. Museum samples may be incomplete, have an unusual morphology, or represent juvenile individuals, all of which complicate accurate identification. In some cases, inaccurate identification can lead to false biogeographic reconstructions with cascading impacts on paleontological and paleoecological research. Here, we analyzed an unusual Equid mandible found in the Far North of the Taymyr peninsula that was identified morphologically as Equus hemionu...
Vázquez-Boland JA, Meijer WG.Rhodococcus equi is the only recognized animal pathogenic species within an extended genus of metabolically versatile Actinobacteria of considerable biotechnological interest. Best known as a horse pathogen, R. equi is commonly isolated from other animal species, particularly pigs and ruminants, and causes severe opportunistic infections in people. As typical in the rhodococci, R. equi niche specialization is extrachromosomally determined, via a conjugative virulence plasmid that promotes intramacrophage survival. Progress in the molecular understanding of R. equi and its recent rise as a nove...
Cucchi T, Mohaseb A, Peigné S, Debue K, Orlando L, Mashkour M.The Plio-Pleistocene evolution of and the subsequent domestication of horses and donkeys remains poorly understood, due to the lack of phenotypic markers capable of tracing this evolutionary process in the palaeontological/archaeological record. Using images from 345 specimens, encompassing 15 extant taxa of equids, we quantified the occlusal enamel folding pattern in four mandibular cheek teeth with a single geometric morphometric protocol. We initially investigated the protocol accuracy by assigning each tooth to its correct anatomical position and taxonomic group. We then contrasted the ph...
Simmons DR, Letcher PM, Powell MJ, Longcore JE.The order Lobulomycetales contains chytrids from soil, freshwater and marine habitats; environmental DNA sampling has indicated that representatives of this order might be found in deep ocean localities. We describe Alogomyces tanneri as the first lobulomycetalean chytrid isolated from horse manure; A. tanneri is also the first species in the order to possess a rumposome in its zoospore. This species widens the range of habitats, ultrastructural variation and thallus morphology for Lobulomycetales.
Novick LR, Shade CK, Catley KM.This article reports the results of an experiment involving 108 college students with varying backgrounds in biology. Subjects answered questions about the evolutionary history of sets of hominid and equine taxa. Each set of taxa was presented in one of three diagrammatic formats: a noncladogenic diagram found in a contemporary biology textbook or a cladogram in either the ladder or tree format. As predicted, the textbook diagrams, which contained linear components, were more likely than the cladogram formats to yield explanations of speciation as an anagenic process, a common misconception am...
Asher RJ, Bennett N, Lehmann T.An unprecedented level of confidence has recently crystallized around a new hypothesis of how living placental mammals share a pattern of common descent. The major groups are afrotheres (e.g., aardvarks, elephants), xenarthrans (e.g., anteaters, sloths), laurasiatheres (e.g., horses, shrews), and euarchontoglires (e.g., humans, rodents). Compared with previous hypotheses this tree is remarkably stable; however, some uncertainty persists about the location of the placental root, and (for example) the position of bats within laurasiatheres, of sea cows and aardvarks within afrotheres, and of der...
Zhang L, Hu M, Chilton NB, Huby-Chilton F, Beveridge I, Gasser RB.The expansion segments or divergent (D) domains in the large subunit (LSU) of the ribosomal DNA have been suggested as genetic markers for taxonomic and/or phylogenetic studies of parasites. In the present study, we assessed the degree of sequence variation in the D3 domain and flanking core regions of the LSU for 21 species of equine strongyles (Strongylida: Strongylidae) and determined which positions in the secondary structure of the LSU were associated with the nucleotide alterations. No intraspecific sequence variation was detected in 17 species, for which multiple individual worms were a...
Hung GC, Chilton NB, Beveridge I, Gasser RB.In this study, molecular data sets were used to address the controversies relating to the systematics of strongyloid nematodes of equids utilising morphological data sets. DNA sequences of the first and second internal transcribed spacers (ITS-1 and ITS-2) of ribosomal DNA were determined for 30 species of equine strongyles and the systematic relationships reconstructed using phenetic and phylogenetic tree-building methods. The molecular data provided support for the hypothesis that the genera with large subglobular buccal capsules are ancestral to those with small cylindrical buccal capsules,...
Barton MD, Hughes KL.A total of 189 isolates of Rhodococcus equi and related organisms and 16 marker strains representing the genera Rhodococcus and Corynebacterium were screened for 160 unit characters in a numerical taxonomic study. Analysis of the data indicated that R. equi forms a relatively homogeneous cluster distinctly separated from the recognized species of Rhodococcus and Corynebacterium (sensu stricto). Other members of the genus Rhodococcus are soil organisms and R. equi appears to fit into the genus on ecological as well as taxonomic grounds. It seems unlikely that R. equi could be a gastrointestinal...
Asher RJ, Bennett N, Lehmann T.An unprecedented level of confidence has recently crystallized around a new hypothesis of how living placental mammals share a pattern of common descent. The major groups are afrotheres (e.g., aardvarks, elephants), xenarthrans (e.g., anteaters, sloths), laurasiatheres (e.g., horses, shrews), and euarchontoglires (e.g., humans, rodents). Compared with previous hypotheses this tree is remarkably stable; however, some uncertainty persists about the location of the placental root, and (for example) the position of bats within laurasiatheres, of sea cows and aardvarks within afrotheres, and of der...
Hung GC, Chilton NB, Beveridge I, Gasser RB.In this study, molecular data sets were used to address the controversies relating to the systematics of strongyloid nematodes of equids utilising morphological data sets. DNA sequences of the first and second internal transcribed spacers (ITS-1 and ITS-2) of ribosomal DNA were determined for 30 species of equine strongyles and the systematic relationships reconstructed using phenetic and phylogenetic tree-building methods. The molecular data provided support for the hypothesis that the genera with large subglobular buccal capsules are ancestral to those with small cylindrical buccal capsules,...
Vázquez-Boland JA, Meijer WG.Rhodococcus equi is the only recognized animal pathogenic species within an extended genus of metabolically versatile Actinobacteria of considerable biotechnological interest. Best known as a horse pathogen, R. equi is commonly isolated from other animal species, particularly pigs and ruminants, and causes severe opportunistic infections in people. As typical in the rhodococci, R. equi niche specialization is extrachromosomally determined, via a conjugative virulence plasmid that promotes intramacrophage survival. Progress in the molecular understanding of R. equi and its recent rise as a nove...
Cucchi T, Mohaseb A, Peigné S, Debue K, Orlando L, Mashkour M.The Plio-Pleistocene evolution of and the subsequent domestication of horses and donkeys remains poorly understood, due to the lack of phenotypic markers capable of tracing this evolutionary process in the palaeontological/archaeological record. Using images from 345 specimens, encompassing 15 extant taxa of equids, we quantified the occlusal enamel folding pattern in four mandibular cheek teeth with a single geometric morphometric protocol. We initially investigated the protocol accuracy by assigning each tooth to its correct anatomical position and taxonomic group. We then contrasted the ph...
Cirilli O, Pandolfi L, Rook L, Bernor RL.Evolution of the genus Equus has been a matter of long debate with a multitude of hypotheses. Currently, there is no consensus on either the taxonomic content nor phylogeny of Equus. Some hypotheses segregate Equus species into three genera, Plesippus, Allohippus and Equus. Also, the evolutionary role of European Pleistocene Equus stenonis in the origin of the zebra-ass clade has been debated. Studies based on skull, mandible and dental morphology suggest an evolutionary relationship between North American Pliocene E. simplicidens and European and African Pleistocene Equus. In this contributio...
Barton MD, Hughes KL.A total of 189 isolates of Rhodococcus equi and related organisms and 16 marker strains representing the genera Rhodococcus and Corynebacterium were screened for 160 unit characters in a numerical taxonomic study. Analysis of the data indicated that R. equi forms a relatively homogeneous cluster distinctly separated from the recognized species of Rhodococcus and Corynebacterium (sensu stricto). Other members of the genus Rhodococcus are soil organisms and R. equi appears to fit into the genus on ecological as well as taxonomic grounds. It seems unlikely that R. equi could be a gastrointestinal...
Zhang L, Hu M, Chilton NB, Huby-Chilton F, Beveridge I, Gasser RB.The expansion segments or divergent (D) domains in the large subunit (LSU) of the ribosomal DNA have been suggested as genetic markers for taxonomic and/or phylogenetic studies of parasites. In the present study, we assessed the degree of sequence variation in the D3 domain and flanking core regions of the LSU for 21 species of equine strongyles (Strongylida: Strongylidae) and determined which positions in the secondary structure of the LSU were associated with the nucleotide alterations. No intraspecific sequence variation was detected in 17 species, for which multiple individual worms were a...
Novick LR, Shade CK, Catley KM.This article reports the results of an experiment involving 108 college students with varying backgrounds in biology. Subjects answered questions about the evolutionary history of sets of hominid and equine taxa. Each set of taxa was presented in one of three diagrammatic formats: a noncladogenic diagram found in a contemporary biology textbook or a cladogram in either the ladder or tree format. As predicted, the textbook diagrams, which contained linear components, were more likely than the cladogram formats to yield explanations of speciation as an anagenic process, a common misconception am...
Simmons DR, Letcher PM, Powell MJ, Longcore JE.The order Lobulomycetales contains chytrids from soil, freshwater and marine habitats; environmental DNA sampling has indicated that representatives of this order might be found in deep ocean localities. We describe Alogomyces tanneri as the first lobulomycetalean chytrid isolated from horse manure; A. tanneri is also the first species in the order to possess a rumposome in its zoospore. This species widens the range of habitats, ultrastructural variation and thallus morphology for Lobulomycetales.
Vershinina AO, Kapp JD, Baryshnikov GF, Shapiro B.Museum collections are essential for reconstructing and understanding past biodiversity. Many museum specimens are, however, challenging to identify. Museum samples may be incomplete, have an unusual morphology, or represent juvenile individuals, all of which complicate accurate identification. In some cases, inaccurate identification can lead to false biogeographic reconstructions with cascading impacts on paleontological and paleoecological research. Here, we analyzed an unusual Equid mandible found in the Far North of the Taymyr peninsula that was identified morphologically as Equus hemionu...
Sangal V, Goodfellow M, Jones AL, Sutcliffe IC.Opinion 106 of the Judicial Commission has clarified the nomenclature of the taxon variously named , ' and . As a consequence, we present here the genus name and that of its nomenclatural type species, comb. nov., for valid publication and propose the reclassification of four rhodococcal species as novel combinations in the genus, namely Guo et al. 2015 comb. nov., Kämpfer . 2014 comb. nov., Li . 2015 comb. nov. and Lee . 2019 comb. nov. In addition, we note that a clinical isolate, strain 86-07 (=W8901), likely represents an additional species within the genus . Nearly a century after ...
Kalmykov NP.Morphological features of the teeth were studied in the three-toed horse Hipparion tchicoicum from the Pliocene of Western Transbaikalia (Russia). Several diagnostic signs of the Chicoi hipparion were described for the first time to provide criteria for distinguishing the taxon among other fossils of three-toed horses and estimating their real diversity at the final stage of their distribution in Inner Asia.
Landry Z, Roloson MJ, Fraser D.The metapodials of extinct horses have long been regarded as one of the most useful skeletal elements to determine taxonomic identity. However, recent research on both extant and extinct horses has revealed the possibility for plasticity in metapodial morphology, leading to notable variability within taxa. This calls into question the reliability of metapodials in species identification, particularly for species identified from fragmentary remains. Here, we use ten measurements of metapodials from 203 specimens of four Pleistocene horse species from eastern Beringia to test whether there are s...
Aldayarov N, Tulobaev A, Salykov R, Jumabekova J, Kydyralieva B, Omurzakova N, Kurmanbekova G, Imanberdieva N, Usubaliev B, Borkoev B, Salieva K....In their centuries-old nomadic life, since their livestock was the backbone of their lives, the Kyrgyz people used a variety of wild medicinal plants for ethnoveterinary practices. However, the plants used for the treatment of livestock ailments never have been recorded, except rarely in local publications. In this study, we present the HSHR (homemade single species herbal remedy reports), their methods of preparation and application, and the livestock ailments for which these remedies were used. Objective: The collect data from the five different high-altitude valleys of the Kyrgyz Republic o...
Martin de Bustamante M, Gomez D, MacNicol J, Hamor R, Plummer C.The objective of this study was to describe and compare the fecal bacterial microbiota of horses with equine recurrent uveitis (ERU) and healthy horses using next-generation sequencing techniques. Fecal samples were collected from 15 client-owned horses previously diagnosed with ERU on complete ophthalmic examination. For each fecal sample obtained from a horse with ERU, a sample was collected from an environmentally matched healthy control with no evidence of ocular disease. The Illumina MiSeq sequencer was used for high-throughput sequencing of the V4 region of the 16S rRNA gene. The relativ...
