Implications For Phylogeny Research Articles

Recent Advances in Genetics and Genomics of Snub-Nosed Monkeys (Rhinopithecus) and Their Implications for Phylogeny, Conservation, and Adaptation.

The snub-nosed monkey genus Rhinopithecus (Colobinae) comprises five species (Rhinopithecus roxellana, Rhinopithecus brelichi, Rhinopithecus bieti, Rhinopithecus strykeri, and Rhinopithecus avunculus). They are range-restricted species occurring only in small areas in China, Vietnam, and Myanmar. All extant species are listed as endangered or critically endangered by the International Union for Conservation of Nature (IUCN) Red List, all with decreasing populations. With the development of molecular genetics and the improvement and cost reduction in whole-genome sequencing, knowledge about evolutionary processes has improved largely in recent years. Here, we review recent major advances in snub-nosed monkey genetics and genomics and their impact on our understanding of the phylogeny, phylogeography, population genetic structure, landscape genetics, demographic history, and molecular mechanisms of adaptation to folivory and high altitudes in this primate genus. We further discuss future directions in this research field, in particular how genomic information can contribute to the conservation of snub-nosed monkeys.

Mitochondrial genome of Diploderma micangshanense and its implications for phylogeny of the genus Diploderma

The lizard Diploderma micangshanense, which belongs to the family Agamidae is endemic to China. Here, we determined the complete mitogenome of D. micangshanense using an Illumina Hiseq X Ten sequencer. This mitogenome’s structure is a typical circular molecule of 16,467 bp in length, consisting of 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and a control region. The overall base composition of D. micangshanensis is 34.1% A, 23.64% T, 13.62% C, and 28.64% G with a slight AT bias of 57.74%. Most mitochondrial genes except ND6 and seven tRNAs were encoded on the heavy strand. Notably, the trnP gene was encoded on the heavy strand instead of its typical light strand position, providing an example of gene inversion in vertebrate mitogenomes. Phylogenetic analysis indicated that D. micangshanensis had a close relationship with D. zhaoermii.

Comparative mitochondrial genomics of five Dermestid beetles (Coleoptera: Dermestidae) and its implications for phylogeny

Dermestid beetles (Coleoptera: Dermestidae) are important pests of various stored products, posing potential threats to international trade. Their detailed characterization on molecular basis is a pre-requisite for proper identification and for understanding of their phylogenetic relationships. In this work, the whole mitochondrial genomes (mitogenomes) of Trogoderma granarium, Dermestes lardarius, D. ater, Attagenus augustatus augustatus and Attagenus unicolor japonicus were firstly sequenced to update the database using the next-generation sequencing technique. Based on the selected model species, a comparative analysis of four Dermestidae genera was performed. The mitochondrial genomes of these five species above showed high similarity in nucleotide composition, base composition and gene order, including 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs), 2 ribosomal RNAs (rRNAs) and a non-coding control region, which was similar to most of Coleoptera species. The phylogenetic analysis based on the PCGs and two rRNAs indicated that the relationships within Dermestidae were reconstructed as (((Trogoderma + Anthrenus) + Attagenus) + Dermestes) using both Maximum Likelihood (ML) and Bayesian Inference (BI) analysis. However, more mitogenomes should be sequenced to obtain a more holistic view of the whole family. This study not only showed the mitogenomes of five Dermestidae species and their high conservativeness, but also discussed its implications for reconstructing a more comprehensive phylogeny of dermestids.

A new Eocene cylindrodontid rodent from the Erlian Basin (Nei Mongol, China) and its implications for phylogeny and biochronology

ABSTRACTWe report a new early–middle Eocene cylindrodontid rodent, Gobiocylindrodon ulausuensis, gen. et sp. nov., from the Ula Usu West locality, Erlian Basin, Nei Mongol, China. Gobiocylindrodon ulausuensis is morphologically more primitive than known later cylindrodontids in having lower-crowned molars, less-rounded upper molars in occlusal view, a more oblique hypolophid on p4, a slightly anterolabially extended hypoconid on m1–3, and a narrow posterosinusid posteriorly and a broad mesosinusid anteriorly on the lower cheek teeth. The lower incisor enamel of G. ulausuensis is pauciserial. Our phylogenetic analysis of a data matrix including 14 taxa and 40 morphological characters reveals that G. ulausuensis is a basal cylindrodontid. Gobiocylindrodon ulausuensis casts new light on early cylindrodontid evolution in Asia and provides new evidence for mammalian dispersals between Asia and North America during the early–middle Eocene. Gobiocylindrodon-bearing strata are probably Arshantan in age.

Comparative analysis of sound production between the bighead goby Ponticola kessleri and the round goby Neogobius melanostomus: Implications for phylogeny and systematics

Divergence in acoustic traits between closely related species can be explained by phylogenetic history. In gobies, phylogenies reconstructed with acoustic signals primarily overlap with studies based on morphological or molecular data. Here, sound production of the two Ponto-Caspian gobies, Neogobius melanostomus and Ponticola kessleri, was recorded in controlled conditions and compared to determine the degree of interspecific acoustic variation across benthophilin gobies. Both species produced tonal-like sounds characterized by unique temporal and spectral properties during agonistic and reproductive intraspecific interactions, while the acoustic comparison revealed that the vocalizations of these two species differ in almost every acoustic property. N. melanostomus vocal structure was characterised by short (c. 100 ms), low-frequency (< 100 Hz) tonal sounds repeated at a relatively faster rate, while P. kessleri sounds appeared as a broadband, downward frequency modulated longer calls (c. 450 ms). Some acoustic features (sound rate and duration) proved to be stereotyped and could be considered a species-specific trait that could potentially be utilized to discriminate males or used by females for mate assessment. The tonal sounds appear to have a deeper origin within the Benthophilinae subfamily, as all acoustically investigated species to date have been able to produce this sound type. The recorded vocal repertoire represents a baseline for future comparative acoustic studies among the benthophilin gobies, aiming to gain additional information on the evolution of acoustic communication within Ponto-Caspian gobies and highlighting their importance in reconstructing phylogenetic relationships.

In the footsteps of Darwin: dwarf male attachment sites in scalpellid barnacles (Crustacea: Cirripedia: Thoracica) – implications for phylogeny and the evolution of sexual systems

In the footsteps of Darwin: dwarf male attachment sites in scalpellid barnacles (Crustacea: Cirripedia: Thoracica) – implications for phylogeny and the evolution of sexual systems

A new species of mycophagous Rentonium (Coleoptera: Cleroidea: Trogossitidae) based on larvae and adults, and a catalogue of Rentoniinae

Adults and associated larvae of Rentonium bicolor sp. nov. are described from New Zealand (North Island) and represent the first associated larvae of the Rentoniinae. Larvae and adults were found among the fruiting bodies of Hypocrea rufa (Pers.) Fr. (Ascomycota: Hypocreaceae). The larvae are morphologically similar to a previously described and undetermined larva but differ from it by the unpaired, hook-like urogomphus, four stemmata, and the apical antennal seta subequal in length to the antenna. Potential implications for phylogeny of Cleroidea are discussed. A catalogue of the genera and species of Rentoniinae is provided, along with comments about the status of Rentonellum loebli Kolibáč.http://www.zoobank.org/urn:lsid:zoobank.org:pub:936541AB-1802-4C09-9032-7EF1FAAC912E

The evolution and utility of ribosomal ITS sequences in Bambusinae and related species: divergence, pseudogenes, and implications for phylogeny

Ribosomal internal transcribed spacer (ITS) sequences are commonly used for phylogenetic reconstruction because they are highly reiterated as components of rDNA repeats, and hence are often subject to rapid homogenization through concerted evolution. Concerted evolution leads to intragenomic uniformity of repeats even between loci on nonhomologous chromosomes. However, a number of studies have shown that the ITS polymorphism within individuals is quite common. The molecular systematics of Bambusinae and related species were recently assessed by different teams using independently generated ITS sequences, and the results disagreed in some remarkable features. Here we compared the ITS sequences of the members of Bambusa s. l., the genera Dendrocalamus, Dinochloa, Gigantochloa, Guadua, Melocalamus, Monocladus, Oxytenanthera, Thyrsostachys, Pleioblastus, Pseudosasa and Schizostachyum.We have reanalysed the ITS sequences used by different research teams to reveal the underlying patterns of their different results. After excluding the sequences suspected to represent paralogous loci, a phylogenetic analysis of the subtribe Bambusinae species were performed using maximum parsimony and maximum-likelihood methods. The implications of the findings are discussed. The risk of incorporating ITS paralogues in plant evolutionary studies that can distort the phylogenetic signal should caution molecular systematists.

New pelomedusoid turtles from the late Palaeocene Cerrejón Formation of Colombia and their implications for phylogeny and body size evolution

Pelomedusoides comprises five moderate-sized extant genera with an entirely Southern Hemisphere distribution, but the fossil record of these turtles reveals a great diversity of extinct taxa, documents several instances of gigantism, and indicates a complex palaeobiogeographical history for the clade. Here, we report new pelomedusoid turtle fossils from the late Palaeocene Cerrejón Formation of Colombia. The most complete of these is represented by a large skull (condylobasal length = 16 cm) and is described as Carbonemys cofrinii gen. et sp. nov. (Podocnemidae). Carbonemys is incorporated into a parsimony analysis utilizing a modified morphological character matrix designed to test relationships within Panpelomedusoides, with the addition of molecular data from seven genes (12S RNA, cytochrome b, ND4, NT3, R35, RAG-1 and RAG-2) drawn from previous studies of extant Podocnemidae. C. cofrinii is recovered within Podocnemidae in the results of both morphology-only and combined morphological and molecular (total evidence) analyses. However, molecular data strongly impact the inferred relationships of C. cofrinii and several other fossil taxa by altering the relative positions of the extant taxa Peltocephalus and Erymnochelys. This resulted in C. cofrinii being recovered within the crown clade Podocnemidae in the morphology-only analysis, but outside of Podocnemidae in the combined analysis. Two Panpodocnemid turtle taxa of uncertain affinities are represented by new diagnostic shell material from the Cerrejón Formation, though we refrain from naming them pending discovery of associated cranial material. One of these shells potentially belongs to C. cofrinii and represents the second largest pleurodiran turtle yet discovered. Analysis of pelomedusoid body size evolution suggests that climatic variation is not the primary driver of major body size changes. Cerrejón turtles also demonstrate that at least two major subclades of Podocnemidae were already in place in the neotropics by the Early Cenozoic.

Early ontogeny of Middle Jurassic hiatellids from a wood-fall association: implications for phylogeny and palaeoecology of Hiatellidae

We provide a detailed description of exceptionally well-preserved specimens of Hiatella (Pseudosaxicava) phaseolus (Eudes-Deslongchamps) from Middle Bathonian (Middle Jurassic) clays of the CzA™stochowa Ore-bearing Clay Formation at Gnaszyn (southern Poland). The juvenile shell is illustrated for the first time, allowing detailed interpretation of the ontogenetic history of these bivalves. The specimens settled on sunken driftwood that served as an attachment surface and thus acted as a ‘benthic island’ on the otherwise muddy seafloor. A review of the Mesozoic record of the bivalve family Hiatellidae shows that the group appeared in the earliest Jurassic, shortly after the end-Triassic extinction event. The Jurassic species of Hiatella (Pseudosaxicava) do not significantly differ from the Recent species of Hiatella (Hiatella) with regard to major shell characters. However, the absence of hinge teeth and the presence of multiple rows of tiny tubercles on the juvenile dissoconch of Pseudosaxicava clearly distinguish the two subgenera. Although highly variable with regard to morphology and behaviour (boring, nestling or byssal attachment), the Hiatellidae are a conservative group that have not changed significantly since the Mesozoic.

DNA Barcodes of Arabian Partridge and Philby's Rock Partridge: Implications for Phylogeny and Species Identification

Recently, DNA barcoding based on mitochondrial cytochrome c oxidase subunit I (COI) has gained wide attention because of simplicity and robustness of these barcodes for species identification including birds. The current GenBank records show the COI barcodes of only one species, chukar partridge (Alectoris chukar), of the Alectoris genus. In this study, we sequenced the 694 bp segment of COI gene of the two species including, Arabian partridge (Alectoris melanocephala) and Philby’s rock partridge (Alectoris philbyi) of the same genus. We also compared these sequences with earlier published barcodes of chukar partridge. The pair-wise sequence comparison showed a total of 53 variable sites across all the 9 sequences from 3 species. Within-species variable sites were found to be 4 (Alectoris chukar), 0 (Alectoris philbyi) and 3 (Alectoris melanocephala). The genetic distances among the 9 individuals varied from 0.000 to 0.056. Phylogenetic analysis using COI barcodes clearly discriminated the 3 species, while Alectoris chukar was found to be more closely related to Alectoris philbyi. Similar differentiation was also observed using 1155 bp mitochondrial control region (CR) sequences suggesting the efficiency of COI gene for phylogenetic reconstruction and interspecific identification. This is the first study reporting the barcodes of Arabian partridge and Philby’s rock partridge.

Respiratory proteins in Sipunculus nudus — Implications for phylogeny and evolution of the hemerythrin family

Three major classes of respiratory proteins are known, hemoglobin, molluscan and arthropod hemocyanin, and hemerythrin (Hr). Similar to hemoglobin, respiratory Hr is packed into erythrocytes floating in the coelomic fluid and is only known from sipunculids, brachiopods, and priapulids. Owing to this scattered distribution, the presence of Hr is generally assumed to be the plesiomorphic condition without phylogenetic importance. By sequencing 2000 Expressed Sequence Tags (ESTs) from Sipunculus nudus, we found 75 Hr-coding ESTs assembled to 20 cDNA contigs classified as four distinct Hr isoforms: three polymeric Hrs (subunit A, A', and B) and the monomeric myo-hemerythrin (myoHr). Phylogenetic analyses revealed a clade of annelid and sipunculan monomeric Hrs, distinct from polymeric Hrs. Monomeric Hrs from annelids and sipunculids can be clustered together using Maximum Likelihood tree-building and network analyses, as well as applying Bayesian methods. Three distinct Hr clusters were found for S. nudus, suggesting a new monomeric Hr isoform.

Dyrosaurid (Crocodyliformes: Mesoeucrocodylia) Fossils from the Upper Cretaceous and Paleogene of Mali: Implications for Phylogeny and Survivorship across the K/T Boundary

We describe new dyrosaurid fossils from three localities in Mali, representing strata of Maastrichtian, Paleocene, and Eocene ages. The fossils significantly extend the temporal and geographic ranges of several known dyrosaurid taxa. Rhabdognathus keiniensis and Chenanisuchus lateroculi are identified for the first time from Maastrichtian sediments. Additional material is referred to Phosphatosaurus gavialoides and, tentatively, the genus Sokotosuchus. These discoveries represent the first occurrence of Chenanisuchus and possibly of Sokotosuchus from Mali. Previously unknown morphological character states are incorporated into existing data matrices, reducing the amount of missing data. Phylogenetic analyses largely corroborate prior hypotheses of dyrosaurid relationships, but indicate a need for new characters to resolve the relationships of certain genera and species. The occurrence of both basal (e.g., Chenanisuchus lateroculi) and highly nested (e.g., Rhabdognathus keiniensis) members of Dyrosauridae on both sides of the K/T boundary indicates that dyrosaurid diversification was well underway by the latest Cretaceous, and that most, if not all dyrosaurid species survived the extinction event. The geology of the Mali’s Tilemsi Valley is clarified; some rocks previously assigned to the Iullemmeden Basin actually represent extensions of other basins: the Taoudeni Basin and Gao Trench.

An independent heterotachy model and its implications for phylogeny and divergence time estimation

Heterotachy or variation of rates-across-sites and lineages is widespread (e.g., Fitch and Markowitz, 1970; Uzzel and Corbin, 1971; Lopez et al., 2002) and can cause biased tree estimation (Lockhart et al., 1998; Susko et al., 2004; Inagaki et al., 2004). Kolaczkowski and Thornton (2004) described an intriguing heterotachy model that lead to topological bias for likelihood-based methods. That work generated a significant amount of discussion (e.g., Spencer et al., 2005; Lockhart and Steel, 2005; Gadagkar and Kumar, 2005) and raises questions about what forms of heterotachy might create these effects. Here we consider a model that we will refer to as the random effects rate variation model (RERV) which differs from common evolutionary models only in that the rate at a site is assigned independently to each edge in the tree according to a gamma distribution. In contrast, in the commonly used gamma rates-across-sites model of Yang (1993, 1994), each site has a different rate drawn from a gamma distribution but this rate is fixed for all edge lengths. The main heterotachy model that has been implemented in practice is the covarion or covariotide model described in Huelsenbeck (2002) and Galtier (2001). The model considered here similarly allows rates to vary across sites and lineages but has computational advantages. By comparison with covarion implementations, the model does not require a two-dimensional Markov chain implementation and compared with gamma rates-across-sites models, which

Comparative pollen morphology and ultrastructure of Platanus: Implications for phylogeny and evaluation of the fossil record

Pollen of Platanus was studied using light (LM) and electron microscopy (SEM and TEM). Overall, pollen is uniform in modern Platanus (small, tricolpate, prolate to spheroidal, reticulate, semitectate). A number of characters, however, display remarkable variability within a taxon and even a single anther (size; foveo‐reticulate, fine to coarse reticulate ornamentation). Platanus kerrii (subgenus Castaneophyllum) differs from the remaining species by its high and “folded” reticulum and possibly the smooth colpus membrane. Moreover, to our knowledge, pollen of the P. kerrii – type is not known from the fossil record. The exine in modern and fossil Platanaceae shows great structural similarity, but the thickness of the foot layer within the ectexine is less variable and normally smaller in modern taxa. Furthermore, in Early Cretaceous to Early Cainozoic Platanaceae a number of distinct pollen types occurred that are not known within the modern Platanus. Considering pollen of Platanaceae from the Early Cretaceous to today, a dynamic picture of the evolution of the family emerges. In the first phase (Early Cretaceous) pollen of extinct genera such as Aquia differed considerably from modern Platanus and shows strong similarity to basal eudicot taxa such as Ranunculales (e.g. Lardizabalaceae). The Late Cretaceous Platananthus hueberi displays a distinct coarse reticulum that is unknown from modern Platanus but similar to some taxa of Hamamelidaceae (e.g. Exbucklandia). After the first phase of eudicot radiation that appears to have been characterized by strongly reticulate evolution, platanaceous diversity decreased in the course of the Cainozoic. Despite this, the pollen type of the modern subgenus Castaneophyllum (P. kerrii type) seems to be an innovation that originated after the initial radiation of the family.

Spermatogenesis in Serpulorbis (Mollusca: Vermetoidea) and its implications for phylogeny of gastropods

Summary Spermatogenesis in Serpulorbis squamigerus and S. variabilis was studied with light and electron microscopy. In spite of their unusual method of accomplishing internal fertilization by the use of spermatophores, the genesis and structure of vermetid eusperm is in most respects typical of Hypsogastropoda (sensu Ponder and Lindberg, 1997). However, vermetid eusperm have evolved a complex acrosome with a number of unique features not previously described in this taxon. Parasperm of vermetids are easily distinguished by their unique shape, but are more similar in their development to parasperm of some Hypsogastropoda than they are to those of Cerithioidea and Campaniloidea. One feature that was thought previously to provide a link with Cerithioidea and related groups, is the presence of the tail brush in mature parasperm. However, in Serpulorbis variabilis the tailbrush is reduced or lost in some parasperm at maturity and in S. squamigerus it is completely replaced by the terminal bulb, which is synapomorphic with Hypsogastropoda. Also, unlike Cerithioidea, paraspermiogenesis in Vermetoidea always involves the complete elimination of the nucleus and no acrosome is formed. For the first time, nuclear degradation in parasperm of Vermetoidea is shown to progress by an apoptotic mechanism. The many nuclear vesicles that pinch off during this process are broken down by lysosomes secreted by the Golgi body, such that nuclear material is not detected in the mature parasperm. This mechanism of “nuclear apoptosis” is different from that observed in Cerithioidea and Littorinoidea, but is similar to that in some Hypsogastropoda. The Golgi body is involved in producing numerous large glycoprotein granules that fill the body of the parasperm and form a sheath around the axonemal core. This core of axonemes extends anteriorly into a long compound flagellum that produces little motility. Eusperm and parasperm are sealed together inside a spermatophore that dissolves and releases its contents once inside the female reproductive tract. At this point eusperm and parasperm are separate, but in Vermetus alii there is evidence that, prior to this, they form spermatozeugmata in the vas deferens, which is a derived feature characteristic of some Hypsogastropoda. This and other evidence supports the conclusion of Healy (1988b) that Vermetoidea are not closely related to “lower” caenogastropods, such as Cerithioidea. Rather, they are closer in sperm charactersitics to “lower” Hypsogastropoda, which include superfamilies such as Littorinoidea, Stromboidea, Janthinoidea and Triphoroidea.

Ultrastructure of opisthosomal chaetae in Vestimentifera (Pogonophora, Obturata) and implications for phylogeny

AbstractSchulze, A. 2000. Ultrastructure of opisthosomal chaetae in Vestimentifera (Pogonophora, Obturata) and implications for phylogeny. —Acta Zoologica(Stockholm)82: 127–135The posterior segmented body region of Vestimentifera bears rows of uncini that function to anchor the animal within its tube. SEM studies of five vestimentiferan species reveal intraspecific and interspecific variation in the number of chaetigerous segments and the arrangement of uncini within a given segment. The portion of an uncinus that extends beyond the epidermis comprises two opposing groups of teeth that probably correspond to the capitium and subrostral process of polychaete uncini, and a distinct protuberance between them, interpreted as a rostrum. InRidgeia piscesae, the uncini are formed by chaetal follicles, consisting of a chaetoblast, a follicle cell and an epidermis cell. The chaetal shaft is elongate and composed of up to 40 hollow cylinders that are invaded at their base by microvilli from the apical part of the chaetoblast. Opisthosomal chaetae in perviate Pogonophora are usually restricted to four per segment and are of a rod‐shaped type. It is hypothesized that the rod‐shaped chaetae represent reduced hooked chaetae probably derived from a condition such as found in Monilifera. Uncini of Pogonophora, Sabellida, Terebellida and Oweniida are considered homologous but details of chaetal design may be due to functional adaptations and thus do not represent reliable characters for phylogenetic studies on higher taxonomic levels than genera or potentially families.

Cytoplasmic and shell fine structure of Tetrapetalon elegans (Polycystinea) and comparisons to Hexacontium spp. with implications for phylogeny and taxonomy of the Spumellarida

The cytoplasmic fine structure of Tetrapetalon elegans (synonym?: Hexalonche amphisiphon) is characterized by loosely arranged radial lobes extending from a centrally located, lobate nucleus. The capsular wall is thin (ca. 250 nm) composed of a membranous envelope, and there is no evidence of fissures as occur in thicker central capsular walls, e.g., Thalassicolla sp. The fusules project through a thin, slightly flared collar that appears to make cytoplasmic bridges to the fusule strand at places, but is sometimes unconnected, leaving small openings. These openings may permit exchange of fluid and gases between the central capsule and the surrounding space containing the extracapsulum. The fusule strands are connected to the intracapsular lobes by a short cytoplasmic segment ca. 300 to 500 nm in length, and each extends through the fusule collar that projects above the surface of the capsular wall forming a tube-like extension. The fine structural characteristics of the cytoplasm and of the porous, laminar skeleton are very different from other genera with porous skeletons (e.g., Hexacontium) and supports current revisions in taxonomy placing Tetrapetalon and Hexacontium in separate families in contrast to Haeckel's original designation. These findings are discussed in relation to toxonomy of the Spumellarida.

New ceratomorph perissodactyls (Mammalia) from the Middle and Late Eocene of Mongolia: their implications for phylogeny and dating

Eight species rank taxa are described from Eocene sites in the Gobi Desert, Mongolia.Irdinolophusgen. nov. is erected forDesmatotherium mongolienseOsborn and forIrdinolophus? tuiensissp. nov. The genus is placed at the stem of the family Deperetellidae. Intraspecific variation inTeleolophus magnusis documented for the first time;Pachylophusis synonymized withTeleolophus; andDeperetellacf.birmanicais recorded far north of its previously known range in Burma. The first known lower teeth ofColodon inceptussupport referral ofDesmatotherium fissumtoColodon. The stratigraphic range of the hyracodontidArdyniais extended back from the late Eocene to the early middle Eocene. A range of primitive tapiroids and rhinocerotoids are analysed cladistically to resolve the problematic affinities of the extinct families Deperetellidae and Rhodopagidae. The Deperetellidae are shown to belong to a monophyletic superfamily Tapiroidea, whilst the Rhodopagidae belongs to the Rhinocerotoidea, but is distinct from the Hyracodontidae.Veragromovia, previously synonymized with the tapiroidHelaletes,is resurrected as a valid genus within the Rhodopagidae. Tsagan Khutel and other sites in the Kholbolchi Formation may be older than Irdinmanhan faunas in Asia, equating with those from the Arshanto Formation of China of probable early Lutetian or latest Ypresian age. The Irdinmanhan Mergen fauna may be slightly older than that from Irdin Manha, because of the primitive aspect of itsLophialetes

New ceratomorph perissodactyls (Mammalia) from the Middle and Late Eocene of Mongolia: their implications for phylogeny and dating

Eight species rank taxa are described from Eocene sites in the Gobi Desert, Mongolia.Irdinolophusgen. nov. is erected forDesmatotherium mongolienseOsborn and forIrdinolophus? tuiensissp. nov. The genus is placed at the stem of the family Deperetellidae. Intraspecific variation inTeleolophus magnusis documented for the first time;Pachylophusis synonymized withTeleolophus; andDeperetellacf.birmanicais recorded far north of its previously known range in Burma. The first known lower teeth ofColodon inceptussupport referral ofDesmatotherium fissumtoColodon. The stratigraphic range of the hyracodontidArdyniais extended back from the late Eocene to the early middle Eocene. A range of primitive tapiroids and rhinocerotoids are analysed cladistically to resolve the problematic affinities of the extinct families Deperetellidae and Rhodopagidae. The Deperetellidae are shown to belong to a monophyletic superfamily Tapiroidea, whilst the Rhodopagidae belongs to the Rhinocerotoidea, but is distinct from the Hyracodontidae.Veragromovia, previously synonymized with the tapiroidHelaletes,is resurrected as a valid genus within the Rhodopagidae. Tsagan Khutel and other sites in the Kholbolchi Formation may be older than Irdinmanhan faunas in Asia, equating with those from the Arshanto Formation of China of probable early Lutetian or latest Ypresian age. The Irdinmanhan Mergen fauna may be slightly older than that from Irdin Manha, because of the primitive aspect of itsLophialetes