Origin of symbiotic gut spirochetes as key players in the nutrition of termites

Termites harbour symbiotic spirochetes in their hindguts, which have long been considered treponemes, although they represent separate lines of descent from known species of Treponema. ‘Termite gut treponemes’ have a mutualistic relationship with the host termites with their physiological properties including CO₂-reductive acetogenesis, from which the resulting acetate fulfils most of the respiratory requirement of the host. Song and co-workers showed that a spirochetal isolate (strain RmG30) from a Madeira cockroach represents the earliest branching lineage of extremely diverse termite (Treponema) cluster I and was a simple homolactic fermenter, suggesting that CO₂-reductive acetogenesis exhibited by some members of termite cluster I originated via horizontal gene transfer. Phylogenomic and 16S rRNA sequence-based phylogenetic analyses indicated a deeply-branched sister clade containing termite cluster I was distinguishable as a family-level lineage. In this context, a new family, ‘Termitinemataceae’ has been proposed for this clade. Strain RmG30 has been designated as the type strain of Breznakiella homolactica gen. nov. sp. nov. named after John A. Breznak, an American microbiologist distinguished in termite gut microbiology. The study has posed important questions for the future, including the actual roles of the termite spirochetes in each termite lineage and the evolutionary process of their physiological properties.     

Characterization and phylogenomic analysis of Breznakiella homolactica gen. nov. sp. nov. indicate that termite gut treponemes evolved from non-acetogenic spirochetes in cockroaches

Spirochetes of the genus Treponema are surprisingly abundant in termite guts, where they play an important role in reductive acetogenesis. Although they occur in all termites investigated, their evolutionary origin is obscure. Here, we isolated the first representative of ‘termite gut treponemes’ from cockroaches, the closest relatives of termites. Phylogenomic analysis revealed that Breznakiella homolactica gen. nov. sp. nov. represents the most basal lineage of the highly diverse ‘termite cluster I', a deep-branching sister group of Treponemataceae (fam. ‘Termitinemataceae’) that was present already in the cockroach ancestor of termites and subsequently coevolved with its host. Breznakiella homolactica is obligately anaerobic and catalyses the homolactic fermentation of both hexoses and pentoses. Resting cells produced acetate in the presence of oxygen. Genome analysis revealed the presence of pyruvate oxidase and catalase, and a cryptic potential for the formation of acetate, ethanol, formate, CO₂ and H₂ - the fermentation products of termite gut isolates. Genes encoding key enzymes of reductive acetogenesis, however, are absent, confirming the hypothesis that the ancestral metabolism of the cluster was fermentative, and that the capacity for acetogenesis from H₂ plus CO₂ - the most intriguing property among termite gut treponemes - was acquired by lateral gene transfer.     

MOLECULAR PHYLOGENY AND TAXONOMY OF THE AEGAGROPILA CLADE (CLADOPHORALES,ULVOPHYCEAE), INCLUDING THE DESCRIPTION OF AEGAGROPILOPSIS GEN. NOV. AND PSEUDOCLADOPHORA GEN. NOV.1

The Aegagropila clade represents a unique group of cladophoralean green algae occurring mainly in brackish and freshwater environments. The clade is sister to the species‐rich and primarily marine Cladophora and Siphonocladus lineages. Phylogenetic analyses of partial LSU and SSU nrDNA sequences reveal four main lineages within the Aegagropila clade, and allow a taxonomic reassessment. One lineage consists of two marine ‘Cladophora’ species, for which the new genus Pseudocladophora and the new family Pseudocladophoraceae are proposed. For the other lineages, the family name Pithophoraceae is reinstated. Within the Pithophoraceae, the earliest diverging lineage includes Wittrockiella and Cladophorella calcicola, occurring mainly in brackish and subaerial habitats. The two other lineages are restricted to freshwater. One of them shows a strong tendency for epizoism, and consists of Basicladia species and Arnoldiella conchophila. The other lineage includes Aegagropila, Pithophora and a small number of tropical ‘Cladophora’ species. The latter are transferred to the new genus Aegagropilopsis. Previously, polypyramidal pyrenoids had been suggested to be apomorphous for this clade, but we report the finding of both polypyramidal and bilenticular pyrenoids in members of the Pithophoraceae, and thus show that this character has no diagnostic value.     

UPDATING THE GENUS DICTYOSPHAERIUM AND DESCRIPTION OF MUCIDOSPHAERIUM GEN. NOV. (TREBOUXIOPHYCEAE) BASED ON MORPHOLOGICAL AND MOLECULAR DATA1

Recent molecular analyses of Dictyosphaerium strains revealed a polyphyletic origin of this morphotype within the Chlorellaceae. The type species Dictyosphaerium ehrenbergianum Nägeli formed an independent lineage within the Parachlorella clade, assigning the genus to this clade. Our study focused on three different Dictyosphaerium species to resolve the phylogenetic position of remaining species. We used combined analyses of morphology; molecular data based on SSU and internally transcribed spacer region (ITS) rRNA sequences; and the comparison of the secondary structure of the SSU, ITS‐1, and ITS‐2 for species and generic delineation. The phylogenetic analyses revealed two lineages without generic assignment and two distinct clades of Dictyosphaerium‐like strains within the Parachlorella clade. One clade comprises the lineages with the epitype strain of D. ehrenbergianum Nägeli and two additional lineages that are described as new species (Dictyosphaerium libertatis sp. nov. and Dictyosphaerium lacustre sp. nov.). An emendation of the genus Dictyosphaerium is proposed. The second clade comprises the species Dictyosphaerium sphagnale Hindák and Dictyosphaerium pulchellum H. C. Wood. On the basis of phylogenetic analyses, complementary base changes, and morphology, we describe Mucidosphaerium gen. nov with the four species Mucidosphaerium sphagnale comb. nov., Mucidosphaerium pulchellum comb. nov., Mucidosphaerium palustre sp. nov., and Mucidosphaerium planctonicum sp. nov.     

An extraordinary new genus of spiders from Western Australia with an expanded hypothesis on the phylogeny of Tetragnathidae (Araneae)

We describe Pinkfloydia Hormiga & Dimitrov gen. nov. , a new genus of tetragnathid spiders from Western Australia and study its phylogenetic placement. The taxon sampling from our previous cladistic studies was expanded, with the inclusion of representatives of additional tetragnathid genera and outgroup taxa. Sequences from six genetic markers, 12S, 16S, 18S, 28S, cytochrome c oxidase subunit 1, and histone 3, along with morphological and behavioural data were used to infer tetragnathid relationships. These data were analysed using parsimony (under both static homology and dynamic optimization) and Bayesian methods. Our results indicate that Pinkfloydia belongs to the ‘Nanometa’ clade. We also propose a revised set of synapomorphies to define this lineage. Based on the new evidence presented here we propose a revised hypothesis for the intrafamilial relationships of Tetragnathidae and show that Mimetidae is most likely the sister group of Tetragnathidae. The single species in this genus so far, Pinkfloydia harveii Dimitrov& Hormiga sp. nov. , is described in detail and its web architecture documented and illustrated. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 161 , 735–768.     

Characterization of a new cosmopolitan genus of trypanosomatid parasites,Obscuromonas gen. nov. (Blastocrithidiinae subfam. nov.)

The expanding phylogenetic tree of trypanosomatid flagellates (Kinetoplastea: Trypanosomatidae) contains a long-known and phylogenetically well-supported species-rich lineage that was provisionally named as the ‘jaculum’ clade. Its members were found in representatives of several unrelated families of heteropteran bugs captured in South and Central America, Europe, Africa, and Asia. However, this group resisted introduction into the culture, a needed prerequisite for its proper characterization. Here we describe four new cultivable species, which parasitize various parts of their hosts’ intestine, including the thoracic and abdominal part of the midgut, hindgut, and Malpighian tubules. Morphologically, the cultured flagellates vary from relatively short stumpy promastigotes to long slender leptomonad cells. Some species form straphangers (cyst-like amastigotes) both in vivo and in vitro, initially attached to the basal part of the flagellum of the mother cell, from which they subsequently detach. To formally classify this enigmatic monophyletic cosmopolitan clade, we erected Obscuromonas gen. nov., including five species: O. modryi sp. nov. (isolated from the true bug host species Riptortus linearis captured in the Philippines), O. volfi sp. nov. (from Catorhintha selector, Curaçao), O. eliasi sp. nov. (from Graptostethus servus, Papua New Guinea), O. oborniki sp. nov. (from Aspilocoryphus unimaculatus, Madagascar), and O. jaculum comb. nov. (from Nepa cinerea, France). Obscuromonas along with the genus Blastocrithidia belongs to the newly established Blastocrithidiinae subfam. nov.     

Physiological characterization of anaerobic ammonium oxidizing bacterium ‘Candidatus Jettenia caeni’

To date, six candidate genera of anaerobic ammonium‐oxidizing (anammox) bacteria have been identified, and numerous studies have been conducted to understand their ecophysiology. In this study, we examined the physiological characteristics of an anammox bacterium in the genus ‘Candidatus Jettenia’. Planctomycete KSU‐1 was found to be a mesophilic (20–42.5°C) and neutrophilic (pH 6.5–8.5) bacterium with a maximum growth rate of 0.0020 h^?1. Planctomycete KSU‐1 cells showed typical physiological and structural features of anammox bacteria; i.e. ²⁹N₂ gas production by coupling of ¹⁵NH₄⁺ and ¹⁴NO₂^?, accumulation of hydrazine with the consumption of hydroxylamine and the presence of anammoxosome. In addition, the cells were capable of respiratory ammonification with oxidation of acetate. Notably, the cells contained menaquinone‐7 as a dominant respiratory quinone. Proteomic analysis was performed to examine underlying core metabolisms, and high expressions of hydrazine synthase, hydrazine dehydrogenase, hydroxylamine dehydrogenase, nitrite/nitrate oxidoreductase and carbon monoxide dehydrogenase/acetyl‐CoA synthase were detected. These proteins require iron or copper as a metal cofactor, and both were dominant in planctomycete KSU‐1 cells. On the basis of these experimental results, we proposed the name ‘Ca. Jettenia caeni’ sp. nov. for the bacterial clade of the planctomycete KSU‐1.     

Systematics and phylogeny of Vasseuromys (Mammalia,Rodentia, Gliridae) with a description of a new species from the late Miocene of eastern Europe

Vasseuromys is a species‐rich genus of small‐ to medium‐sized glirids spanning the latest Oligocene to late Miocene of Europe and western Asia. Despite extensive discoveries over the past 50 years, little phylogenetic work has been done on Vasseuromys. This study presents the first phylogenetic analysis of the genus that includes all the described species and a new taxon Vasseuromys tectus sp. nov. from the late Miocene of eastern Europe, providing the first insights into the evolutionary relationships within the clade. Results suggest that the genus is clearly paraphyletic. Two strongly supported genus‐level clades are recognized within ‘Vasseuromys’: a restricted Vasseuromys clade (containing the three species, V. pannonicus, V. rugosus and V. tectus) and the Glirulus clade that includes ‘Vasseuromys’ duplex. The remaining ‘Vasseuromys’ species are found to constitute a set of paraphyletic taxa, with the polyphyletic ‘Ramys’ nested within it. The genus Gliruloides is synonymized with Glirulus. Vasseuromys tectus sp. nov. is the most derived member of the genus in having a greater number of cheek teeth ridges including constantly present anterotrope, centrotrope, second prototrope on M1–2, third metatrope on M2, two to three posterotropids on p4 and strong ectolophids on lower molars. The results of the study confirm a European origin for Vasseuromys while suggesting that the late Miocene species of the genus dispersed from the east in the early Turolian.     

Non‐monophyly of Bostrychia simpliciuscula (Ceramiales,Rhodophyta): Multiple species with very similar morphologies,a revised taxonomy of cryptic species

The discovery of a plethora of cryptic species in many algal groups has led to speculation as to the causes of this observation and has affected taxonomy, with reluctance to give names to species that look identical. While this is defensible for monophyletic cryptic species complexes, both our understanding of similar morphologies (crypsis) and nomenclature is challenged when we encounter non‐monophyletic ‘cryptic’ species. Bostrychia simpliciuscula is a wide‐ranging species in which multiple cryptic species are known. Our increased sampling shows that this species consists of four lineages that do not form a clade, but lineages are sister to species with different morphologies. Careful morphological examination shows that characters, especially branched monosiphonous laterals and rhizoid morphology in haptera, are able to distinguish these four lineages into two groups, that are still not monophyletic. The similar morphologies in these lineages could be due to convergence, but not developmental constraints or lack of time to diverge morphologically; or possibly maintenance of a generalized body plan. These lineages appear to have specific biogeographic patterns and these will be used to propose a new taxonomy. B. simpliciuscula is now confined to the tropics. Another of these lineages matches a previously described species, B. tenuissima, that was synonymized with B. simpliciuscula and is from cold temperate Australasia, and is resurrected. Another lineage is found in Japan in which a previous name is also available, B. hamana‐tokidae; the last lineage is found in central New South Wales, morphologically it resembles B. tenuissima, with which it overlaps in distribution around Sydney, and is named as a new species, B. kingii sp. nov.     

A polyphasic approach to the study of the genus Nitzschia (Bacillariophyta): three new planktonic species from the Adriatic Sea

The paraphyletic diatom genus Nitzschia comprises over 1000 morphologically distinct pennate taxa, known from the benthos and plankton of freshwater, brackish, and marine environments. The principal diagnostic characters for delimitation of Nitzschia species include valve shape, the position and structure of the raphe, presence/absence and shape of the proximal raphe endings and terminal raphe fissures, areola structure, and specific morphometric features such as cell size, and stria and fibula density. In this study, we isolated 12 diatom strains into culture from samples collected at the surface or greater depths of the southeastern Adriatic Sea. Morphological analyses included LM, SEM, and TEM observations, which, along with specific morphometric features, allowed us to distinguish three new Nitzschia species. These findings were congruent with the results of phylogenetic analyses performed on nuclear‐encoded SSU (18S) rDNA and chloroplast‐encoded rbcL and psbC genes. One of the new species (Nitzschia dalmatica sp. nov.) formed a lineage within a clade of Bacillariaceae containing members of the Nitzschia sect. Dubiae, which was sister to Psammodictyon. A second lineage was part of a novel clade that is significantly distinct from other Nitzschia species sequenced so far and includes Nitzschia adhaerens sp. nov. and N. cf. adhaerens. A further new species was found, Nitzschia inordinata sp. nov., which appeared as the sister group to the N. adhaerens clade and the conopeoid Nitzschia species in our phylogenetic trees. Our findings contribute to the overall diversity of genus Nitzschia, especially in identifying some deep branches within the Bacillariaceae, and highlight under‐scoring of this genus in marine plankton.     

<Emphasis Type="Italic">Kazachstania intestinalis</Emphasis> sp. nov., an ascosporogenous yeast from the gut of passalid beetle <Emphasis Type="Italic">Odontotaenius disjunctus</Emphasis>

Three ascosporogenous yeast strains were isolated from the gut of the passalid beetle, Odontotaenius disjunctus, inhabiting on rotten oak trees. DNA sequence comparison and other taxonomic characteristics identified the strains as a novel species in the genus Kazachstania. The name Kazachstania intestinalis sp. nov. (type strain EH085^T = ATCC MYA-4658^T = CBS 11839^T) is proposed for the strains. The yeast is homothallic, producing persistent asci with 1–4 spheroidal ascospores. Molecular phylogeny from ribosomal RNA gene sequences placed this novel species on the basal lineage of a clade including Kazachstania lodderae, Kazachstania exigua, Kazachstania martiniae, and other related Kazachstania spp., but none of those species was a close sister to K. intestinalis.     

Chondrichthyan‐like scales from the Middle Ordovician of Australia

Abstract: Microvertebrate sampling of the Stairway Sandstone (Darriwilian, Middle Ordovician, central Australia) has yielded scales that are chondrichthyan‐like in their overall construction, and Tantalepis gatehousei gen. et sp. nov. is erected here to describe these specimens. Tantalepis gatehousei gen. et sp. nov. is the stratigraphically oldest microsquamous taxon described thus far, and the ‘shark‐like’ appearance of the scales may extend the chondrichthyan lineage back into the Middle Ordovician. The presence of ‘shark‐like’ scales in the fossil record some 50 myr prior to the first articulated chondrichthyan body fossils and 44 myr before the first clearly identifiable chondrichthyan teeth suggests there is a considerable scope for the recovery of articulated specimens with which to document the early history of crown gnathostomes. Traditional hypotheses of phylogenetic relationships among early jawed vertebrates were recently challenged by the proposal of a radically different tree topology. However, the development of a new data set specifically addressing scale‐based characters is required before taxa such as Tantalepis, that are based upon disarticulated remains alone, can be firmly placed within the emerging, revised, evolutionary narrative.     

Natronobacillus azotifigens gen. nov., sp. nov., an anaerobic diazotrophic haloalkaliphile from soda-rich habitats

Gram-positive bacteria capable of nitrogen fixation were obtained in microoxic enrichments from soda soils in south-western Siberia, north-eastern Mongolia, and the Lybian desert (Egypt). The same organisms were obtained in anoxic enrichments with glucose from soda lake sediments in the Kulunda Steppe (Altai, Russia) using nitrogen-free alkaline medium of pH 10. The isolates were represented by thin motile rods forming terminal round endospores. They are strictly fermentative saccharolytic anaerobes but tolerate high oxygen concentrations, probably due to a high catalase activity. All of the strains are obligately alkaliphilic and highly salt-tolerant natronophiles (chloride-independent sodaphiles). Growth was possible within a pH range from 7.5 to 10.6, with an optimum at 9.5–10, and within a salt range from 0.2 to 4 M Na⁺, with an optimum at 0.5–1.5 M for the different strains. The nitrogenase activity in the whole cells also had an alkaline pH optimum but was much more sensitive to high salt concentrations compared to the growing cells. The isolates formed a compact genetic group with a high level of DNA similarity. Phylogenetic analysis based on 16S-rRNA gene sequences placed the isolates into Bacillus rRNA group 1 as a separate lineage with Amphibacillus tropicus as the nearest relative. In all isolates the key functional nitrogenase gene nifH was detected. A new genus and species, Natronobacillus azotifigens gen. nov., sp. nov., is proposed to accommodate the novel diazotrophic haloalkaliphiles. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. The GenBank accession numbers for the 16S rRNA gene of the novel strains are EU143681-EU143690 and EU850814-EU850816; for the nifH gene the accession numbers are EU542601, EU563380-EU563386 and EU850817-EU850819.     

An osteology‐based appraisal of the phylogeny and evolution of kangaroos and wallabies (Macropodidae: Marsupialia)

Macropodids are the most diverse group of marsupial herbivores ever to have evolved. They have been the subject of more phylogenetic studies than any other marsupial family, yet relationships of several key clades remain uncertain. Two important problem areas have been the position of the merrnine (Lagostrophus fasciatus) and the phylogenetic proximity of tree‐kangaroos and rock‐wallabies. Our osteological analysis revealed strong support for a plesiomorphic clade ( Lagostrophinae subfam. nov. ) containing Lagostrophus and Troposodon, which is likely to have originated in the early Miocene. The extinct short‐faced kangaroos (Sthenurinae) emerged in the middle Miocene as the sister lineage to a clade containing all other living kangaroos and wallabies (Macropodinae). New Guinea forest wallabies ( Dorcopsini trib. nov. ) are the most plesiomorphic macropodines; the other two main lineages include tree‐kangaroos and rock‐wallabies (Dendrolagini), and ‘true’ kangaroos and wallabies (Macropodini). These phylogenetic outcomes are broadly consistent with the results of recent molecular studies, although conflicts remain over the relative positions of some macropodins (e.g. Setonix, Onychogalea, and Wallabia). Given the presence of derived dendrolagins and macropodins in early Pliocene localities, it is probable that most macropodine genera originated in the late Miocene. Key functional–adaptive trajectories within the craniodental and locomotory systems of the dominant macropodid lineages represent varying responses to the spread of drier, open habitats following the Miocene Climatic Optimum. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 159 , 954–987.     

Osteology and relationships of Thaiichthys nov. gen.: a Ginglymodi from the Late Jurassic – Early Cretaceous of Thailand

Abstract: The osteology of Thaiichthys buddhabutrensis, nov. gen., from the Late Jurassic – Early Cretaceous of Thailand is described on the basis of a collection of well‐preserved specimens. The mode of preservation of the material allows describing the external anatomy, as well as some elements of the internal anatomy (braincase, elements of the vertebral column). Most of the cranial and postcranial skeleton shows a rather conservative anatomy for ‘semionotiformes’, but the jaw apparatus displays specializations. Variations observed in the ossification pattern of the skull roof and of the cheek, in the morphology of the median dorsal scales and in fin rays’ count indicate that caution should be applied when these characters are used in diagnoses and in phylogenetic analyses. A phylogenetic analysis including a set of gars, of ‘semionotiformes’, of Macrosemiiformes and of Halecomorphi shows the following features: (1) the monophyly of Holostei; (2) sister‐pair relationships between Tlayuamichin/Semiolepis, Isanichthys/’Lepidotes’ latifrons and Araripelepidotes/Pliodetes; (3) the latter pair, together with Thaiichthys and possibly ‘Lepidotes’ mantelli, are resolved as stem Lepisosteiformes; and (4) the ‘semionotiformes’ (a group gathering species of Semionotus and Lepidotes) do not form a clade.     

Recognition of a new generic‐level swallow taxon from central Africa

The forest swallow Petrochelidon fuliginosa is a little‐known species endemic to lowland forests in central Africa; for lack of access to high‐quality genetic material, the species has been omitted from all previous molecular phylogenetic studies of the swallows. The species is currently placed in the genus Petrochelidon, within the ‘mud‐nester’ clade of swallows, yet its plumage, morphology, and nesting behavior do not align well with those of other major swallow lineages. As a consequence, upon securing recent specimens and high‐quality tissue samples, we sequenced DNA from two mitochondrial genes and one nuclear marker to place this species in the swallow phylogenetic tree. Our results placed the forest swallow firmly within the ‘mud nester’ clade, but outside of the clade corresponding to Petrochelidon. This outcome led us to document and describe formally a distinct, generic‐level lineage of swallow endemic to the Lower Guinean forest region of central Africa.     

Tales of dracula ants: the evolutionary history of the ant subfamily Amblyoponinae (Hymenoptera: Formicidae)

The ants in the subfamily Amblyoponinae are an old, relictual group with an unusual suite of morphological and behavioural features. Adult workers pierce the integument of their larvae to imbibe haemolymph, earning them the vernacular name ‘dracula ants’. We investigate the phylogeny of this group with a data set based on 54 ingroup taxa, 23 outgroups and 11 nuclear gene fragments (7.4 kb). We find that the genus Opamyrma has been misplaced in this subfamily: it is a member of the leptanilline clade and sister to all other extant Leptanillinae. Transfer of Opamyrma to Leptanillinae renders the Amblyoponinae monophyletic. The enigmatic Afrotropical genus Apomyrma is sister to all other amblyoponines, and the latter cleave into two distinct and well‐supported clades, here termed POA and XMMAS. The POA clade, containing Prionopelta, Onychomyrmex and Amblyopone, is well resolved internally, and its structure supports synonymy of the genus Concoctio under Prionopelta ( syn.n. ). The XMMAS clade comprises two well‐supported groups: (i) a predominantly Neotropical clade, for which we resurrect the genus name Fulakora ( stat.r., stat.n. ), with junior synonyms Paraprionopelta ( syn.n. ) and Ericapelta ( syn.n. ); and (ii) the remaining taxa, or ‘core XMMAS’, which are manifested in our study as a poorly resolved bush of about a dozen lineages, suggesting rapid radiation at the time of their origin. Most of these XMMAS lineages have been assigned to the catch‐all genus Stigmatomma, but the more distinctive elements have been treated as separate genera (Xymmer, Mystrium, Myopopone and Adetomyrma). Resolution of basal relationships in the core XMMAS clade and reconfiguration of ‘Stigmatomma’ to restore monophyly of all named genera will require more extensive genetic data and additional morphological analysis. However, the genus Bannapone can be synonymized under Stigmatomma ( syn.n. ) because it is embedded within a clade that contains S. denticulatum, the type species of Stigmatomma. Divergence dating analysis indicates that crown Amblyoponinae arose in the mid‐Cretaceous, about 107 Ma (95% highest probability density: 93–121 Ma). The POA and XMMAS clades have estimated crown ages of 47 and 73 Ma, respectively. The initial burst of diversification in the core XMMAS clade occurred in the Late Paleocene/Early Eocene (50–60 Ma). Ancestral range reconstruction suggests that amblyoponines originated in the Afrotropics, and dispersed to the Indo‐Malayan region and to the New World. During none of these dispersal events did the ants break out of their cryptobiotic lifestyle.     

The turtles of the Purbeck Limestone Group of Dorset, southern England

The turtles from the Purbeck Limestone are revised and it is concluded that there are four shell‐based cryptodire species present, namely Pleurosternon bullockii, ‘Glyptops’typocardium comb. nov., Helochelydra anglica comb. nov.,Hylaeochelys latiscutata. There is also one skull‐based species, Dorsetochelys delairi, which may prove to be the skull of ‘Glyptops’, Hylaeochelys or an unknown shell‐type. All other taxa are junior synonyms except ‘Chelone’obovata Owen, 1842 and Tretosternon punctatum Owen, 1842 which are nomina dubia, the material being unfigured and either lost or incorrectly associated. Other taxonomic conclusions are that (1) because Tretosternon is a nomen dubium, the next senior name for this Purbeck–Wealden genus is Helochelydra Nopcsa, 1928; (2) ‘Pleurosternon’typocardium and ‘Glyptops’ruetimeyeri are synonymous, the senior combination being ‘Glyptops’typocardium; (3) the Purbeck ‘Tretosternon’ material is combined with the holotype and only specimen of Platychelys? anglica as Helochelydra anglica comb. nov.; (4) Hylaeochelys emarginata and H. sollasi are junior synonyms of Hylaeochelys latiscutata; (5) one of Owen's ‘lost’ syntypes of ‘Tretosternon punctatum’ has been recognised and is a plastron of Hylaeochelys latiscutata.