Sister Group Research Articles

Systems Biology of Streptophyte Cell Evolution

More than 500 million years ago, a streptophyte algal population established a foothold on land and started terraforming Earth through an unprecedented radiation. This event is called plant terrestrialization and yielded the Embryophyta. Recent advancements in the field of plant evolutionary developmental biology (evo-devo) have propelled our knowledge of the closest algal relatives of land plants, the zygnematophytes, highlighting that several aspects of plant cell biology are shared between embryophytes and their sister lineage. High-throughput exploration determined that routes of signaling cascades, biosynthetic pathways, and molecular physiology predate plant terrestrialization. But how do they assemble into biological programs, and what do these programs tell us about the principal functions of the streptophyte cell? Here, we make the case that streptophyte algae are unique organisms for understanding the systems biology of the streptophyte cell, informing on not only the origin of embryophytes but also their fundamental biology.

A new fanged frog of the genus Limnonectes Fitzinger, 1843 (Anura: Dicroglossidae) from Langbian Plateau, southern Vietnam

We describe a new frog of the genus Limnonectes from the Langbian Plateau in southern Vietnam based on morphological and molecular analyses. Limnonectes splendissimus sp. nov. shares morphological characteristics similar to L. poilani from central Vietnam yet is distinguishable from its congeners based on the following combination of diagnostic characters: large body-size (SVL 104.1–107.0 mm in three adult males, 87.2–97.7 mm in two adult females); head length longer than wide (HW/HL = 0.91±0.01 in adult males, 0.87±0.08 in adult females); adult males having an enlarged head height and a nuptial pad on finger I; eye diameter about three-fifths of tympanum-eye distance in adult males (ED/TED = 0.62±0.13) and longer than tympanum-eye distance in adult females (ED/TED = 1.40±0.02); distinct tympanum; presence of vomerine teeth; a tendency for a more prominent odontoid height (OH 8.0 ± 0.6 mm in adult males, 4.5±0.9 mm in adult females); throat surface in juveniles very distinct with black and white pattern that covers both the throat and anterior half of venter, and latter half of venter yellow. Phylogenetic analyses place the new species as the sister species of L. poilani. The new species differs from its congeners by an uncorrected p-distances in 16S sequences ranging from 8.2% (vs. L. poilani) to 14.6% (vs. L. dabanus).

The first report from Poland and larvae description of Eukiefferiella dittmari Lehmann, 1972 (Diptera: Chironomidae) based on morphological and molecular characteristics

Eukiefferiella is a large genus in the family Chironomidae with over 50 species worldwide. Their immature stages have so far been described in many species in the western Palearctic. Nevertheless, some species are still known only from adult males. Presented below is a description of Eukiefferiella dittmari Lehmann, 1972 larvae first recorded in Poland in the pristine river Rawka. The larvae were collected from water moss and identified to the species level using a DNA barcode from BOLD database. E. dittmari larvae belong to E. ilkleyensis group having bifid SIII seta, and mentum with wide central tooth and four pairs of lateral teeth. At the genetic and morphological level, E. dittmari is a sister species to Nearctic E. endobryonia, also an aquatic moss dweller. The phylogenetic relation of these two species should be further investigated.

A draft genome sequence of the common, or spectacled caiman Caiman crocodilus

The common, or spectacled, caiman Caiman crocodilus is an abundant, widely distributed Neotropical crocodilian exhibiting notable morphological and molecular diversification. As the type species for the Caimaninae subfamily - the sister taxa for the subfamily to which members of the genus Alligator belong - C. crocodilus occupies a key position in our understanding of crocodilian and archosaur genetics and evolution. The species also accounts by far for the largest share of crocodilian hides on the global market, with the C. crocodilus hide trade alone valued at about US$86.5 million per year. Thus, the genome sequence of C. crocodilus can potentially be of considerable use for both basic and applied research. We obtained 239,911,946 paired-end reads comprising approximately 72 G bases using Illumina TM sequencing of tissue sampled from a single Caiman crocodilus individual. These reads were de-novo assembled and progressively aligned against the genomes of increasingly related crocodilians; liftoff was used to annotate the draft C. crocodilus genome assembly based on an Alligator mississipiensis (a confamilial species) annotation. The draft C. crocodilus genome assembly and sequences reads have been deposited with the National Center for Biotechnology Information with accession numbers JAGPOW000000000.1 for the assembly, and SRR22317059 for the sequence read archives under Bioproject PRJNA716363.

A new species of lowland karst-dwelling Slender Gecko Hemiphyllodactylus Bleeker, 1860 (Squamata: Gekkonidae) from a karstic archipelago in western Cambodia

A new species of gekkonid lizard is described from Phnom Khpoh, an isolated karstic hill within an extensive karstic archipelago in Battambang Province, western Cambodia. Phylogenetic analysis using a 1041 base pair fragment of the mitochondrial gene ND2 recovered Hemiphyllodactylus khpoh sp. nov. as the sister species of H. pardalis, found 335 km to the west in southern Thailand. Analyses of meristic, morphometric, and categorical characters of morphology and color pattern differentiated H. khpoh sp. nov. from both the morphologically distinct H. pardalis and the very similar Hemiphyllodactylus sp. from Phnom Kulen, approximately 130 km to the northeast in Siem Reap Province. The statistical morphological analyses and comparisons also showed that H. khpoh sp. nov. is well-differentiated from the recently described H. bokor and H. samkos from the nearby Cardamom Mountains as well from species in clade 6—a recently designated lineage from China, Laos, and Vietnam to which H. khpoh sp. nov. + H. pardalis compose the sister lineage. The discovery of H. khpoh sp. nov. highlights the rich but understudied biodiversity of karstic landscapes, emphasizing the need for continued research in the extensive unexplored karstic archipelago of western Cambodia. This region is poised to reveal unparalleled gekkonid diversity, comparable to that observed in the similarly sized karstic archipelago of the Salween Basin in southern Myanmar. Although karstic landscapes are proving to be some of the most biodiverse habitats on the planet, less than 1% of them are afforded any formal protection.

Morphological and Molecular Identification of Sarcocystis arctica in Captive Cheetahs (Acinonyx jubatus) in China Helps Clarify Phylogenetic Relationships with Sarcocystis caninum and Sarcocystis felis

To date, only one case is known where protozoan parasites of the genus Sarcocystis were found to infect cheetahs (Acinonyx jubatus); the cysts in the musculature were morphologically identified as S. felis. Here, we characterized sarcocysts by morphological and molecular methods that were observed in cheetahs who died in zoos in China. Only one type of sarcocyst was present in two of six cheetahs. By light microscopy, the sarcocyst wall was striated, 1.4–2.1 μm thick. Ultrastructurally, the wall had irregular-shaped, small villar protrusions, resembling wall type 9c, similar to those of S. arctica, S. caninum, and S. felis. The samples shared their highest molecular identity values with those of S. arctica and S. caninum: 99.9–100% and 99.8–100% (18S rRNA), 99.5% and 99.3–99.5% (28S rRNA), 95.9–97.5% and 96.3–97.3% (ITS-1), and 99.6% and 99.2–99.7% (cox1), respectively. Compared with ITS-1 of S. felis, identities ranged between 87.5% and 88.9%. Phylogenetic reconstruction revealed that the newly sequenced Sarcocystis clustered with S. arctica and S. caninum, whereas S. felis (ITS-1) and S. canis (ITS-1, 18S rRNA, cox1) were sister species. Thus, we addressed the Sarcocystis species from the cheetahs as S. arctica, which is the first record of a Sarcocystis species believed to be specific for canids as intermediate hosts to infect a feline host.

Multiple plastid losses within photosynthetic stramenopiles revealed by comprehensive phylogenomics.

Ochrophyta is a vast and morphologically diverse group of algae with complex plastids, including familiar taxa with fundamental ecological importance (diatoms or kelp) and a wealth of lesser-known and obscure organisms. The sheer diversity of ochrophytes poses a challenge for reconstructing their phylogeny, with major gaps in sampling and an unsettled placement of particular taxa yet to be tackled. We sequenced transcriptomes from 25 strategically selected representatives and used these data to build the most taxonomically comprehensive ochrophyte-centered phylogenomic supermatrix to date. We employed a combination of approaches to reconstruct and critically evaluate the relationships among ochrophytes. While generally congruent with previous analyses, the updated ochrophyte phylogenomic tree resolved the position of several taxa with previously uncertain placement and supported a redefinition of the classes Picophagea and Synchromophyceae. Our results indicated that the heterotrophic, plastid-lacking heliozoan Actinophrys sol is not a sister lineage of ochrophytes, as proposed recently, but rather phylogenetically nested among them, implying that it lacks a plastid due to loss. In addition, we found the heterotrophic ochrophyte Picophagus flagellatus to lack all hallmark plastid genes yet to exhibit mitochondrial proteins that seem to be genetic footprints of a lost plastid organelle. We thus document, for the first time, plastid loss in two separate ochrophyte lineages. Furthermore, by exploring eDNA data, we enrich the ochrophyte phylogenetic tree by identifying five novel uncultured class-level lineages. Altogether, our study provides a new framework for reconstructing trait evolution in ochrophytes and demonstrates that plastid loss is more common than previously thought.

New Silurian aculiferan fossils reveal complex early history of Mollusca

Mollusca is the second most species-rich animal phylum, but the pathways of early molluscan evolution have long been controversial1, 2, 3, 4–5. Modern faunas retain only a fraction of the past forms in this hyperdiverse and long-lived group. Recent analyses6, 7–8 have consistently recovered a fundamental split into two sister clades, Conchifera (including gastropods, bivalves and cephalopods) and Aculifera9, comprising Polyplacophora (‘chitons’) and Aplacophora. Molluscan evolution in toto is characterized by plasticity in body-plan characters10, but historically aculiferans have been interpreted as more conservative10,11. The few completely preserved aculiferan or aculiferan-like fossils from the early Palaeozoic12, 13, 14, 15, 16, 17, 18–19 have been largely regarded as transitional forms that inform questions of character polarity between the extant polyplacophoran and aplacophoran body forms20,21. The history of early aculiferans, and the morphological and ecological range that they occupied, remain inadequately sampled. Here we describe two new three-dimensionally preserved aculiferan species from the Silurian Herefordshire Lagerstätte22,23, which substantially extend the morphological and ecological range of the clade. Phylogenetic analyses indicate positions within a complex nexus of taxa and suggest reversals in the states of fundamental characters such as the presence of valves and the nature of the foot. In contrast to previous hypotheses of morphological conservatism, evolution in early aculiferans generated a profusion of unusual forms comparable to the diversification of other crown-group molluscs.

Morphology and phylogeny of Itaspiella helgolandica, an interstitial marine flatworm with circumpolar distribution

Flatworms in the family Otoplanidae Hallez, 1892, are ubiquitous inhabitants of the swash zone of marine sandy beaches worldwide. We present new insights into the morphology and phylogenetic position of the otoplanid Itaspiella helgolandica (Meixner, 1938) based on specimens sampled in northern Norway. While the species was originally described from the German coast, it has since been reported in the High Arctic as well as in Greenland, Canada and Alaska, indicating that it has a circumpolar distribution. Apart from these reports, I. helgolandica has received marginal scientific attention beyond the original species description, and apart from drawings, there is not much detailed data available of its morphology. We employ antibody staining and confocal laser microscopy to provide detailed morphological information on the ciliation, myoanatomy and genital organs of specimens of I. helgolandica and compare their morphology with other accounts of the species from across the Arctic. We investigate the phylogenetic relationships of Itaspiella Ax, 1955 through a Bayesian/RAxML analysis of 28S sequences and confirm the morphologically underpinned notion that this genus sits within the subfamily Otoplaninae Hallez, 1910, as the sister taxon to Xenotoplana Ax, Weidemann & Ehlers, 1978. In light of our findings, we explore the question of the apparent circumpolar distribution of Itaspiella in the context of the larger “meiofauna paradox” and touch upon various evolutionary phenomena that may have contributed to phenotypic stability despite its limited dispersal capabilities and the vicariance imposed by the complex recent geological history of the Arctic.

The genus Hermatomyces in Benin, with the description of H. griseomarginatus, sp. nov.

ABSTRACT Intensive mycological surveys in southern Benin focused on species of Hermatomyces (Pleosporales) resulted in the collection and sequencing of numerous specimens on dead plant debris of different hosts. Majority of the collections belonged to the monomorphic species H. sphaericus, except for two specimens of a hitherto unknown species, which is introduced as Hermatomyces griseomarginatus. The fungus was collected on dead twig of Hymenocardia acida still attached to the tree and dead peduncle of Tectona grandis. It is distinct in having sporodochia with a dense and dark gray margin enclosing their lenticular conidia. Phylogenetically, it formed a well-supported lineage sister to two other monomorphic species, H. verrucosus and H. sphaericoides. Two dimorphic species were also found, H. krabiensis and H. nabanheensis, which are reported for the first time outside of Asia. Detailed morphological descriptions are provided, and the diversity of Hermatomyces in Benin is summarized based on published data and results from the GlobalFungi database.

Characterization of Complete Mitochondrial Genome and Phylogeny of Three Echeneidae Species.

Species of the family Echeneidae are renowned for their capacity to adhere to various hosts using a sucking disc. This study aimed to examine the mitochondrial genome characteristics of three fish species (Echeneis naucrates, Remora albescens, and Remora remora) within the family Echeneidae and determine their phylogenetic relationships. The findings revealed that the mitochondrial genome lengths of the three species were 16,611 bp, 16,648 bp, and 16,623 bp, respectively, containing 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs), and a D-loop region. Most PCGs utilized ATG as the initiation codon, while only cox I used the GTG as the initiation codon. Additionally, seven genes employed incomplete termination codons (T and TA). The majority of PCGs in the three species displayed negative AT-skew and GC-skew values, with the GC-skew amplitude being greater than the AT-skew. The Ka/Ks ratios of the 13 PCGs did not exceed 1, demonstrating these species had been subjected to purification selection. Furthermore, only tRNA-Ser (GCT) lacked the D arm, while other tRNAs exhibited a typical cloverleaf secondary structure. Bayesian inference (BI) and maximum likelihood (ML) methods were utilized to construct a phylogenetic tree of the three species based on the 13 PCGs. Remora remora was identified as a distinct group, while R. osteochir and R. brachyptera were classified as sister taxa. This study contributes to the mitochondrial genome database of the family Echeneidae and provides a solid foundation for further systematic classification research in this fish group.

The complete mitochondrial genome of Neobythites sivicola (Jordan & Snyder, 1901) (Ophidiiformes: Ophidiidae)

The genus Neobythites is the most diverse group in the family Ophidiidae. In this study, we assembled and reported the complete mitochondrial genome of N. sivicola for the first time. The mitochondrial genome is 17,316 bp in length and contains 13 PCGs, 2 rRNAs, and 22 tRNAs. Phylogenetic analysis revealed that N. sivicola was the sister species to N. unimaculatus, and Neobythites was closer to Sirembo. This study significantly contributes to the genomic resources available for the family Ophidiidae and the genus Neobythites, providing a valuable molecular resource for further research on the taxonomy and phylogenetics of this family.

Environmental changes and uplift of the Qinghai-Tibet Plateau drive genetic diversification and speciation of the birds.

Being the most magnificent plateau in elevation and size on Earth, the Qinghai-Tibet Plateau has a profound impact on biodiversity due to the unique geographic and climatic conditions. Here we review the speciation patterns and genetic diversity of the birds from the Qinghai-Tibet Plateau in relation to the geological history and climatic changes. First, the uplift of the Qinghai-Tibet Plateau forms a geographic barrier and promotes interspecific and intraspecific genetic differentiation. Second, the uplift of the Qinghai-Tibet Plateau has provided new ecological niches for many endemic birds and facilitated their speciation. Third, the emigration and immigration of bird species between the Qinghai-Tibet Plateau and adjacent zoological regions have promoted species divergence, colonization and dispersal. Furthermore, Pleistocene glaciations and associated climate change drive postglacial colonization and lead to secondary contact, which influenced the genetic divergence of the conspecific populations and sister species. The multi-omics approach has increasingly been used in the studies on the ecological adaptive evolution of birds in Qinghai-Tibet Plateau. Future studies should focus on the role of geological and climatic factors in species differentiation, develop integrative approach with multi-omics methods, and explore the ecological mechanisms of high-elevation adaptation of plateau species. As an important region for biodiversity conservation, more efforts should be implemented to maintain the stability and sustainability of the Qinghai-Tibet Plateau and its ecosystem in light of global change.

Phylogenomic insights into the taxonomy, ecology, and mating systems of the lorchel family Discinaceae (Pezizales, Ascomycota).

Lorchels, also known as false morels (Gyromitra sensu lato), are iconic due to their brain-shaped mushrooms and production of gyromitrin, a deadly mycotoxin. Molecular phylogenetic studies have hitherto failed to resolve deep-branching relationships in the lorchel family, Discinaceae, hampering our ability to settle longstanding taxonomic debates and to reconstruct the evolution of toxin production. We generated 75 draft genomes from cultures and ascomata (some collected as early as 1960), conducted phylogenomic analyses using 1542 single-copy orthologs to infer the early evolutionary history of lorchels, and identified genomic signatures of trophic mode and mating-type loci to better understand lorchel ecology and reproductive biology. Our phylogenomic tree was supported by high gene tree concordance, facilitating taxonomic revisions in Discinaceae. We recognized 10 genera across two tribes: tribe Discineae (Discina, Maublancomyces, Neogyromitra, Piscidiscina, and Pseudodiscina) and tribe Gyromitreae (Gyromitra, Hydnotrya, Paragyromitra, Pseudorhizina, and Pseudoverpa); Piscidiscina was newly erected and 26 new combinations were formalized. Paradiscina melaleuca and Marcelleina donadinii formed their own family-level clade sister to Morchellaceae, which merits further taxonomic study. Genome size and CAZyme content were consistent with a mycorrhizal lifestyle for the truffle species (Hydnotrya spp.), whereas the other Discinaceae genera possessed genomic properties of a saprotrophic habit. Lorchels were found to be predominantly heterothallic-either MAT1-1 or MAT1-2-but a single occurrence of colocalized mating-type idiomorphs indicative of homothallism was observed in Gyromitra esculenta strain CBS101906 and requires additional confirmation and follow-up study. Lastly, we confirmed that gyromitrin has a phylogenetically discontinuous distribution, having been detected exclusively in two distantly related genera (Gyromitra and Piscidiscina) belonging to separate tribes. Our genomic dataset will facilitate further investigations into the gyromitrin biosynthesis genes and their evolutionary history. With additional sampling of Geomoriaceae and Helvellaceae-two closely related families with no publicly available genomes-these data will enable comprehensive studies on the independent evolution of truffles and ecological diversification in an economically important group of pezizalean fungi.

Complete chloroplast genome of Syzygium glomeratum (Myrtaceae) and phylogenetic analysis

Syzygium glomeratum (Lam.) DC., known as “Tram Tron” in Vietnam, is an evergreen tree known for its medicinal properties. To understand the genomic and evolutionary basis of this plant, we sequenced and assembled the complete chloroplast genome of S. glomeratum for the first time, using the Illumina platform. The complete chloroplast of S. glomeratum was 158,469 bp in length and contained a large single-copy region (87,962 bp) and a small single-copy region (18,391 bp) separated by inverted repeat regions (26,058 bp). The genome encoded 85 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. A phylogenetic analysis of 42 Syzygium species revealed significant insight into their evolutionary relationships, indicating a closer relationship between S. glomeratum and its sister group (S. cinereum and S. claviflorum). In conclusion, our results provide genomic information pertaining to the chloroplast genome in S. glomeratum, which is also genetic information useful for further study of biodiversity, conservation, and evolutionary biology.

The phylogeny of Macraucheniidae (Mammalia, Panperissodactyla, Litopterna) at the genus level

Macraucheniidae is one of the most diverse families of South American native ungulates. In the last decade, Macraucheniidae systematics has been the focus of several studies with the aim of enhancing understanding of the diversity and phylogenetic relationships of the group. This study proposes a new phylogenetic hypothesis for the Macraucheniidae based on new characters and new outgroups. We included eight non-macraucheniid taxa as outgroups (three Didolodontidae, one Protolipternidae, two Proterotheriidae, and two Adianthidae); additionally, we included the 16 genera that are currently accepted as belonging to Macraucheniidae based on other cladistic studies. The matrix used in the cladistic analysis comprised 24 taxa and 71 characters. The genus Polymorphis was recovered as the sister taxon of a clade composed of Proterotheriidae + Adianthidae + Macraucheniidae, not as a macraucheniid. Disregarding Polymorphis, all other genera attributed to the Macraucheniidae were recovered in a monophyletic group. We found support for two macraucheniid clades, one formed by Cramaucheniinae (including Theosodon) and the other by all Macraucheniinae with the inclusion of Llullataruca. The late Pliocene Windhausenia was recovered as the sister group of ‘Quaternary macraucheniids’, with Xenorhinotherium as the sister group of Macraucheniopsis + Macrauchenia. Based on this topology, Polymorphis must be considered as family incertae sedis. Our findings have significant implications for understanding the origin and diversification of Macraucheniidae, altering the temporal range of the family to the late Oligocene–Late Pleistocene/Holocene. Additionally, Llullataruca becomes the oldest recorded member of the Macraucheniinae. The evolution of the nasal retraction in the iconic species Macrauchenia patachonica has consistently been interpreted through the lens of the phyletic gradualism model, with Theosodon as the intermediate form between species with totally reduced or absent nasals, and those basal forms with well-developed nasals and terminal nostrils. However, the monophyly of Cramaucheniinae suggests a rapid morphological shift among Macraucheniinae, which fits with a punctuated equilibrium evolutionary model.

A new species of Araripesuchus with durophagous dentition increases the ecological disparity among uruguaysuchid crocodyliforms

Notosuchia is a group of crocodyliforms with mostly terrestrial habits that lived during the Mesozoic and up to the Miocene. Within this group Uruguaysuchidae is so far represented by eight species, six of them clustered in the genus Araripesuchus. Two species of this genus, A. patagonicus and A. buitreraensis, come from different localities in Patagonia (Argentina) from the Candeleros Formation (Cenomanian age). Here we present a third species of Araripesuchus from this formation. The new species comes from the same locality as Araripesuchus buitreraensis, but differs in numerous features including the presence of different molariform teeth. The new species was included in a phylogenetic analysis and, in agreement with previous analyses, Uruguaysuchidae is recovered as monophyletic and placed within Notosuchia as the sister clade of Peirosauridae. Uruguaysuchidae includes all species of Araripesuchus as well as Anatosuchus minor and Uruguaysuchus aznarezi. The new species adds new information to the ecological diversity of the group its bulbous molariforms with a quadrangular occlusal surface bounded by mamelons is interpreted as indicative of a durophagous diet, suggesting the presence of niche partitioning between the two sympatric species A. manzanensis and A. buitreraensis. https://zoobank.org/urn:lsid:zoobank.org:pub:20DA1A36-A12D-40F7-BA69-42ED4FA02CE1

Deep origin of articulation strategies in panarthropods: evidence from a new luolishaniid lobopodian (Panarthropoda) from the Tulip Beds, Burgess Shale

The evolution of articulated sclerites via soft membranes, termed arthrodization, is arguably one of the most critical innovations in animals. Defining the megaphylum Arthropoda, the arthrodization of appendages, or arthropodization, likely predated that of the body, the combination of both being diagnostic of true arthropods (Euarthropoda) – all of these innovations occurring during the Cambrian explosion. Here, thanks to dozens of exceptionally preserved fossils from the Cambrian Wuliuan Stage Burgess Shale (Tulip Beds locality on Mount Stephen, British Columbia, Canada), we show that a distinct but comparable system of imbricated sclerotic elements evolved in the paraphyletic sister group of arthropods, the lobopodians. Entothyreos synnaustrus gen. et sp. nov. has characteristic body plan features of the Collinsovermidae (order Luolishaniida), including anterior limbs for suspension-feeding and stout anchoring posterior limbs. Uniquely, however, E. synnaustrus also displays segmental sclerotic sheets along the trunk, covered in a thin layer of integument, as well as overlapping sclerotized annuli on posterior-most limbs. While the latter elements likely served a protective function, the dorsolateral trunk sheets, which also carry spines, may have facilitated body erection and suspension-feeding. Other luolishaniids possess separate ring-like structures connecting the base of metameric spines which are covered by the apical layer of the lobopodian integument. E. synnaustrus and related taxa illustrate, therefore, an arguably parallel evolution of arthropod-like morphoanatomical features early during the rise of panarthropods. This finding broadens our perspectives on the uniqueness of major synapomorphies and the importance of including canalization in macroevolutionary narratives. http://zoobank.org/urn:lsid:zoobank.org.pub:D4A01784-E587-481A-AB04-A812B4AAE422

Caucasian/Pontic–Mediterranean disjunction and recolonization of Europe by Pomatias (Hyrcania) species (Caenogastropoda, Pomatiidae)

AbstractLehmann, H., Neiber, M. T., & Hausdorf, B. (2024) Caucasian/Pontic–Mediterranean disjunction and recolonization of Europe by Pomatias (Hyrcania) species (Caenogastropoda, Pomatiidae)—Zoologica Scripta, 00, 000‐000. We studied the phylogeny and phylogeography of Pomatias (Hyrcania) species (Caenogastropoda: Pomatiidae) to investigate refugia and the causes of disjunctions in Asia anterior and in southeastern Europe. There is a Caucasian/Pontic–Mediterranean disjunction between the ranges of the sister species P. rivularis from the Caucasus region, the Pontic Mountains and southeastern Europe and P. hyrcanus from the coastal region of the southern Caspian Sea in the north and that of P. glaucus along the Mediterranean coast in the south. The disjunct ranges of the Pomatias (Hyrcania) species are probably relics of a previously more continuous distribution across Anatolia. They became disjunct as a result of the successive aridification of the Anatolian Plateau, which intensified in the late Pliocene following the uplift of the Anatolian Plateau, as has also been shown for several other taxa. The mitochondrial and nuclear genetic diversity of P. rivularis, the most widespread Pomatias (Hyrcania) species, is highest in the populations from the southern Greater Caucasus and the adjacent eastern Pontic Mountains. The southern Greater Caucasus and the coastal regions along the Caspian Sea and the Eastern Mediterranean acted as refugia for the Pomatias (Hyrcania) species after the aridification of the Anatolian Plateau. The low genetic diversity of P. rivularis in Eastern Europe and Ciscaucasia suggests that Miocene and Pliocene fossils identified as P. rivularis from these areas cannot be attributed to this species, that the Pomatias (Hyrcania) populations became extinct there by the Pleistocene, and that P. rivularis recolonized these areas later, probably only in the Holocene.

The last eryopids: Clamorosaurus and Syndyodosuchus from the late Kungurian (Cisuralian, Permian) of Russia revisited

The three Permian (Cisuralian) temnospondyls Syndyodosuchus tetricus, Clamorosaurus nocturnus and C. borealis from the Pechora Coal Basin in Russia, are redescribed. The assignment of Clamorosaurus to the Eryopidae is confirmed, and several new characters are presented in detail. Syndyodosuchus tetricus is identified as an eryopid for the first time, as this taxon was previously regarded as a basal stereospondylomorph. In our phylogenetic analysis, S. tetricus forms a polytomy at the base of the Eryopidae together with Actinodon frossardi and Osteophorus roemeri. More crownward, Glaukerpeton avinoffi and Onchiodon labyrinthicus build a polytomy, followed by O. thuringiensis and Stenokranio boldi as successive sister taxa of a monophyletic Clamorosaurus plus Eryops megacephalus. A reweighted analysis finds A. frossardi at the base of Stereospondylomorpha; the Eryopidae is completely resolved and consists of S. tetricus, O. roemeri, G. avinoffi, O. labyrinthicus, O. thuringiensis, S. boldi and E. megacephalus as successive outgroups to Clamorosaurus. The phylogenetic position of Clamorosaurus among the most derived eryopids is congruent with its young stratigraphic age, whereas for S. tetricus as a basal eryopid a long ghost lineage has to be assumed. Although being coeval, the two genera occurred in different environments, with Clamorosaurus being preserved in lacustrine limestones wheras S. tetricus was found in a coal bed. The lifestyle of these eryopids can best be designated as semi-aquatic.