Basal Dichotomy Research Articles

Taxonomy and evolution of the Canarian Issus Fabricius, 1803 (Hemiptera: Fulgoroidea: Issidae) based on morphological and molecular data

AbstractThe genus Issus Fabricius, 1803 is divided into nine groups of species according to the structure of male genitalia. Phylogenetic position of the Canarian species of the genus is inferred with Bayesian and Maximum Likelihood analyses of four gene markers (COI, H3, CytB, 16S) dataset. Results revealed a well-supported basal dichotomy of the genus into two clades, corresponding to the Mediterranean and the Canarian species. This confirms the monophyly of the Canarian complex of Issus species which is divided into four clades corresponding to I. canariensis, I. rarus, I. bimaculatus, and I. hidipus groups of species. Our results contradict a previously published opinion on the primitiveness of the Canarian species, instead confirming the advanced position of this group. Issus canalaurisi Sergel, 1986 is placed in synonymy under I. cagola Remane, 1985, and I. maderensis Lindberg, 1954 – under I. climacus Fieber, 1876. Issus hidipus Remane 1985 is recorded for the first time from La Gomera and Tenerife Islands, I. padipus Remane 1985 – from El Hierro Island, and I. cagola – from Tenerife Island.

From modern to classic: Classification of the planthopper family Issidae (Hemiptera, Auchenorrhyncha, Fulgoroidea) derived from a total‐evidence phylogeny

AbstractThe Issidae are highly diverse in terms of morphology and species richness. Despite recent efforts, the internal phylogeny and classification of this planthopper family remain controversial. Here, we present a phylogeny of the family inferred with Bayesian and Maximum Likelihood analyses of a nine‐gene molecular dataset (4702 bp) and morphological data (35 characters) across a broad sample of taxa (99 terminals). Based on these results, we verify the taxonomic status of the issid subfamilies, tribes and generic complexes. Results revealed a well‐supported basal dichotomy of the family into two clades, corresponding to the subfamilies Issinae and Hysteropterinae. Within Issinae, the tribes Issini, Thioniini, Sarimini, Hemisphaeriini, Parahiraciini and Kodaianellini were recovered with high support. Four strongly statistically supported clades were revealed within the subfamily Hysteropterinae, but we refrain from taxonomic decisions in the absence of morphological characters to diagnose the clades A–C. Interestingly, the obtained results are in good agreement with L. Melichar's view on Issidae classification suggested more than a century ago. Our results challenge an early Cretaceous origin of the Issidae and the basal split of the family between Neotropical taxa (Thioniini) and the remaining issids.

Molecular phylogeny and systematic of the Schneider's skink Eumeces schneiderii (Daudin, 1802) (Squamata: Scincidae)

Eumeces is a little-known group of skinks with few phylogenies published. Within its distribution range, five subspecies were identified for Schneider's Skink (Eumeces schneiderii) based on color pattern, pholidosis, intra- and inter-subspecific relationships, but the validity of these taxa has yet to be assessed using molecular markers. Here, a robust phylogeny of the E. schneiderii group is presented based on three molecular markers (Cytb, 16S rRNA, and c-mos) from 80 samples collected across Anatolia and the Iranian Plateau. Both Maximum Likelihood and Bayesian Inference approaches were used to infer phylogenetic relationships within this group. The results revealed monophyly of E. schneiderii subspecies and Eumeces persicus. These clades also differ in habitat preferences, with the small-bodied, striped forms generally inhabiting lower elevations and drier environments than the larger, uniform morph E. schneiderii subspecies. Molecular-clock dating based on Cytb implies that most speciation events took place during the Upper Miocene to Lower Pliocene. A strongly supported basal dichotomy of Eumeces schneiderii zarudnyi + E. persicus in the southern and eastern slopes of the Zagros Mountains, with the E. schneiderii subspecies in the western Zagros, was identified in all individual and concatenated trees. Eumeces schneiderii zarudnyi should be elevated to species level and, therefore, we propose the name Eumeces zarudnyi for this taxon, increasing the number of species in the genus to seven described species.

Morphology-based cladistics splinters the century-old dichotomy of the pied harvestmen (Arachnida: Gonyleptoidea: Cosmetidae)

Abstract The cosmetids are conspicuous harvestmen, remarkably diverse in size, shape and colour. However, the effectiveness of all these morphological traits for diagnosing groups is scarcely explored in the literature. Since the early 20th century, the family Cosmetidae has been divided into two subfamilies, Cosmetinae and Discosomaticinae, and there has been no further effort to delimit additional or alternative subfamilial groups. In this analysis, we aim to test the issue of the basal dichotomy of Cosmetinae and Discosomaticinae. Thus, we propose a more comprehensive phylogenetic analysis using both parsimony and Bayesian approach, comprising 103 terminals of Cosmetidae, plus seven outgroup terminals scored for 130 morphological characters. Discosomaticinae is revisited and all its species were included in our matrix. To offer a real challenge to the monophyly of Discosomaticinae, members of 36 genera of Cosmetinae have also been scored. Our results support neither Cosmetinae nor Discosomaticinae sensu Pickard-Cambridge/Roewer as monophyletic groups. We found that Cosmetidae may be organized into a few major clades, which are here diagnosed. Accordingly, taxonomic changes in the arrangement of the family are introduced: description of one new tribe, five new subfamilies and revalidation of a sixth, description of three new genera, and proposition of synonymies, transfers and revalidations at generic level.

Chloroplast genomes of key species shed light on the evolution of the ancient genus Isoetes

AbstractAlthough phylogenetic studies have revealed major clades, the deepest relationships in Isoetes remain unresolved. The use of next‐generation sequencing provides enormous amounts of gene sequences, which allows not only clarification of the basal relationships but also rapid radiations. Plastomes of six key Isoetes species were annotated, revealing a total of 129 or 130 genes, depending on the species. Our phylogenomic analyses comprising representatives of all major clades yielded well‐supported nodes and identical topologies using maximum likelihood and Bayesian inference. The phylogenetic reconstructions detangled the deep relationships in Isoetes and illuminated the more recent radiations in the genus. A basal dichotomy was found that grouped Isoetes spp. from Brazil and South Africa into a clade sister to the remaining Isoetes groups. Interestingly, I. andicola was found to be sister to the North American species complex. Genomic trait mapping analysis showed that the missing introns in the atpF and clpP genes were well conserved in two major clades. The absence of trnK‐UUU was observed in the Brazilian tropical species and in I. velata. Among lycophytes, the gene trnR‐CCG was missing only in I. eludens. In general, genomic traits such as the presence or absence of internal stop codons, a tRNA, and an intron were revealed to be conserved within groups, suggesting that these genomic traits might reveal vital information about the evolution of the genus. This study will contribute to understanding the diversification of Isoetes and the establishment of a better framework to address the evolutionary history of the genus.

Molecular phylogeny of the tribe Philodryadini Cope, 1886 (Dipsadidae: Xenodontinae): Rediscovering the diversity of the South American Racers

South American racers of the tribe Philodryadini are a widespread and diverse group of Neotropical snakes with a complex taxonomic and systematic history. Recent studies failed to present a robust phylogenetic hypothesis for the tribe, mainly due to incomplete taxon sampling. Here we provide the most extensive molecular phylogenetic analysis of Philodryadini available so far, including 20 species (83% of the known diversity) from which six were not sampled previously. Our results reveal that Philodryadini is not monophyletic, but instead includes a central Andean clade formed by Philodryas simonsii, P. tachymenoides, and P. amaru, and a southern and cis-Andean clade including all remaining philodryadines. This discovery requires resurrection of two genera as well as erection of a new tribe of Xenodontinae for the central Andean clade. Within the southern and cis-Andean radiation, our analyses resolve a basal dichotomy separating two main lineages: Clade A, containing the Common Green Racers P. laticeps and P. viridissima and the South American Vine snakes P. georgeboulengeri and P. argentea; and Clade B, including the remaining species of Philodryas sensu stricto. We resurrect the genera Chlorosoma and Xenoxybelis to better represent the monophyly of lineages within the southern and cis-Andean clade.

Old World and New World Phasmatodea: Phylogenomics Resolve the Evolutionary History of Stick and Leaf Insects

Phasmatodea comprises over 3,000 extant species and stands out as one of the last remaining insect orders for which a robust, higher-level phylogenetic hypothesis is lacking. New research suggests that the extant diversity is the result of a surprisingly recent and rapid radiation that has been difficult to resolve with standard Sanger sequence data. In order to resolve the early branching events of stick and leaf insects, we analyzed transcriptomes from 61 species, including 38 Phasmatodea species comprising all major clades and 23 outgroup taxa, including all other Polyneoptera orders. Using a custom-made ortholog set based on reference genomes from four species, we identified on average 2,274 orthologous genes in the sequenced transcriptomes. We generated various sub-alignments and performed maximum-likelihood analyses on several representative datasets to evaluate the effect of missing data and matrix composition on our phylogenetic estimates. Based on our new data, we are able to reliably resolve the deeper nodes between the principal lineages of extant Phasmatodea. Among Euphasmatodea, we provide strong evidence for a basal dichotomy of Aschiphasmatodea and all remaining euphasmatodeans, the Neophasmatodea. Within the latter clade, we recovered a previously unrecognized major New World and Old World lineage, for which we introduce the new names Oriophasmata tax. nov. (“Eastern phasmids”) and Occidophasmata tax. nov. (“Western phasmids”). Occidophasmata comprise Diapheromerinae, Pseudophasmatinae, and Agathemera, whereas all remaining lineages form the Oriophasmata, including Heteropterygidae, Phylliinae, Bacillus, Lonchodidae (Necrosciinae + Lonchodinae), Clitumninae, Cladomorphinae, and Lanceocercata. We furthermore performed a divergence time analysis and reconstructed the historical biogeography for stick and leaf insects. Phasmatodea either originated in Southeast Asia or in the New World. Our results suggest that the extant distribution of Phasmatodea is largely the result of dispersal events in a recently and rapidly diversified insect lineage rather than the result of vicariant processes.

The putative lissamphibian stem-group: phylogeny and evolution of the dissorophoid temnospondyls

AbstractDissorophoid temnospondyls are widely considered to have given rise to some or all modern amphibians (Lissamphibia), but their ingroup relationships still bear major unresolved questions. An inclusive phylogenetic analysis of dissorophoids gives new insights into the large-scale topology of relationships. Based on a TNT 1.5 analysis (33 taxa, 108 characters), the enigmatic taxonPerryellais found to nest just outside Dissorophoidea (phylogenetic defintion), but shares a range of synapomorphies with this clade. The dissorophoids proper are found to encompass a first dichotomy between the largely paedomorphic Micromelerpetidae and all other taxa (Xerodromes). Within the latter, there is a basal dichotomy between the large, heavily ossified Olsoniformes (Dissorophidae + Trematopidae) and the small salamander-like Amphibamiformes (new taxon), which include four clades: (1) Micropholidae (Tersomius,Pasawioops,Micropholis); (2) Amphibamidae sensu stricto (Doleserpeton,Amphibamus); (3) Branchiosauridae (Branchiosaurus,Apateon,Leptorophus,Schoenfelderpeton); and (4) Lissamphibia. The generaPlatyrhinopsandEoscopusare here found to nest at the base of Amphibamiformes. Represented by their basal-most stem-taxa (Triadobatrachus,Karaurus,Eocaecilia), lissamphibians nest withGerobatrachusrather than Amphibamidae, as repeatedly found by former analyses.UUID:http://zoobank.org/dadf36db-e003-4af7-bfa7-44d79bc04450

The phylogeny of lance lacewings (Neuroptera: Osmylidae)

AbstractThe first phylogeny of the lacewing family Osmylidae is presented here based on a total evidence analysis of DNA sequences for multiple gene loci and morphology for representatives of almost all extant genera. Our phylogeny shows a basal dichotomy in the family, with subfamilies Protosmylinae, Spilosmylinae and Gumillinae comprising one lineage, and the other lineage including Osmylinae, Porisminae, Eidoporisminae, Kempyninae and Stenosmylinae. The status of Paryphosmylus Krüger and Lysmus Navás as members of Protosmylinae is affirmed as well as the placement of Gumillinae near Protosmylinae and Spilosmylinae. Our results suggest that Porisminae, Eidoporisminae and Stenosmylinae evolved from a common ancestor, and their relationships, including likely paraphyly of Stenosmylinae, requires further assessment. Divergence time analysis revealed that the family originated during the Late Permian before the break‐up of the supercontinent Pangaea and that present generic distributions are not due to Gondwanan biogeographic events. All major subfamily‐level lineages were present by the end of the Triassic, in agreement with the rich Mesozoic‐aged fossil record for the family.

Rolling into a ball: phylogeny of the Ceratocanthinae (Coleoptera: Hybosoridae) inferred from adult morphology and origin of a unique body enrollment coaptation in terrestrial arthropods

Results of a phylogenetic analysis of all but one of the 43 recognized extant genera of Ceratocanthinae scarab beetles (Coleoptera: Hybosoridae) are reported. The analysis is based on 97 parsimony informative adult morphological characters scored for 61 ingroup and 10 outgroup terminals. This pantropical subfamily of some 366 species is remarkable for the adults’ ability to pack their body into a tight sub-sphere using interlocking exoskeletal structures (= enrollment coaptations). An overview on known biological and fossil data on the subfamily is provided, as well as a list, an overview, a key and illustrations of adults of all Ceratocanthinae genera. The phylogenetic analysis supports a monophyletic Ceratocanthinae (bootstrap 76%) and a basal dichotomy between pantropical Ceratocanthini (97%) and the South American clade (98%) of Scarabatermitini. Ivieolini renders Scarabatermitini paraphyletic. Another well supported internal clade is the Philharmostes group of seven Afrotropical genera (85%). All other inclusive clades detected in the analysis have low bootstrap support (51–65%), likely indicative of limitations of the adult morphological dataset. We also provide a detailed distribution map of Ceratocanthinae and hypothesize about the South American origin of the subfamily, and that of its two subclades: Ceratocanthini and Scarabatermitini + Ivieolini. Overall this paper summarizes all existing information on Ceratocanthinae beetles in an evolutionary context in order to facilitate and stimulate further research on this subfamily.

Patterns of fatty acid composition in seed oils of Cuphea, with new records from Brazil and Mexico

Herbaceous flowering plants of the genus Cuphea (Lythraceae) are noted for synthesizing significant amounts of medium-chain caprylic, capric, lauric, and myristic fatty acids (FAs) in the seed oils, with each species typically emphasizing one of several FAs. The genus is a prospective temperate source of oilseeds for fatty acids used in the manufacture of products as diverse as soaps, food, and biofuels, and it has become a model research system for the study of enzyme-mediated fatty acid synthesis. Seed oil FA composition for 44 species is reported here, including first records for 25 species from South America, primarily from Brazil. Nineteen species are re-analyzed to verify earlier results and expand information on variability in oil composition. An Appendix summarizes seed oil composition of 108 species classified in two subgenera and in 10 of 13 sections. Fifty percent are lauric-acid (C12:0) producers. In South America, the most common FA dominating Cuphea oils is lauric acid. In North America, a secondary center of speciation, seed oils are more diverse; lauric and capric acid (C10:0) are most common, but caprylic (C8:0), myristic (C14:0), linoleic (C18:2), and linolenic acid (18:3) predominate in some species. The dominant FA in the seed oil of each species remains constant throughout its range and in differing habitats, and varies within a species in percentage of total FAs 14–17%. Factors affecting variation are briefly examined. The evolutionary pattern of the major seed oil FAs is explored using data from 61 species mapped to a molecular-based phylogenetic tree. Three significant divergent events indicate that changes in seed oil composition were influential in the adaptive radiation and speciation of Cuphea. The basal dichotomy of the genus separates subg. Cuphea with linoleic acid (C18:2) as dominant FA from subg. Bracteolatae with myristic and lauric acids dominant. Evolution of the dominance of capric acid (C10:0) occurred following introduction of the genus into North America. Greatest diversity of seed oils appears in North America in the most derived clade in the genus, where FAs from caprylic acid (C8:0) to linolenic acid dominate among the species.

DNA sequencing reveals unexpected Recent diversity and an ancient dichotomy in the American marsupial genusMarmosops(Didelphidae: Thylamyini)

To assess species-level diversity in the didelphid marsupial genus Marmosops, we obtained sequence data from the mitochondrial cytochrome b (CYTB) gene from > 200 specimens, including exemplars of every currently recognized species together with multiple specimens of all geographically widespread forms. Analyses of these data using the general mixed Yule coalescent (GMYC) model suggest that the genus could be twice as speciose as currently recognized, but putative species identified by the GMYC criterion require careful evaluation using other data. To assess phylogenetic relationships within Marmosops, we additionally sequenced a large fragment of the breast cancer activating 1 (BRCA1) gene from one specimen each of the putative species identified by the GMYC analyses of CYTB. Maximum likelihood and Bayesian analyses of a concatenated gene (CYTB + BRCA1) matrix revealed a basal dichotomy between two ancient, morphologically diagnosable clades with apparently distinct distributions and adaptive phenotypes. We describe those clades as subgenera and assign 12 nominal taxa to Sciophanes subgen. nov. (with type species Marmosops parvidens) and 27 nominal taxa to the nominotypical subgenus (with type species Marmosops incanus).

Phylogeographic Refinement and Large Scale Genotyping of Human Y Chromosome Haplogroup E Provide New Insights into the Dispersal of Early Pastoralists in the African Continent

Haplogroup E, defined by mutation M40, is the most common human Y chromosome clade within Africa. To increase the level of resolution of haplogroup E, we disclosed the phylogenetic relationships among 729 mutations found in 33 haplogroup DE Y-chromosomes sequenced at high coverage in previous studies. Additionally, we dissected the E-M35 subclade by genotyping 62 informative markers in 5,222 samples from 118 worldwide populations. The phylogeny of haplogroup E showed novel features compared with the previous topology, including a new basal dichotomy. Within haplogroup E-M35, we resolved all the previously known polytomies and assigned all the E-M35* chromosomes to five new different clades, all belonging to a newly identified subhaplogroup (E-V1515), which accounts for almost half of the E-M35 chromosomes from the Horn of Africa. Moreover, using a Bayesian phylogeographic analysis and a single nucleotide polymorphism-based approach we localized and dated the origin of this new lineage in the northern part of the Horn, about 12 ka. Time frames, phylogenetic structuring, and sociogeographic distribution of E-V1515 and its subclades are consistent with a multistep demic spread of pastoralism within north-eastern Africa and its subsequent diffusion to subequatorial areas. In addition, our results increase the discriminative power of the E-M35 haplogroup for use in forensic genetics through the identification of new ancestry-informative markers.

On the systematics and reproductive compatibility in Clariidae based on Osteological and morphometric parameters

Introduction: Member of clariidae are the most cheered foodfish in Africa. This paper presents information on the systematic and the reproductive compatibilities in claridae which appear not to be homologous with the clariid phylogenetic deudogram. Material and Methods: Morphometric and meristic courts were done on the selected species using standard procedures. The species examined were Hetrobranchus longifilis (Valenciennes 1840), Clarias gariepinus (Burchell 1822), Clarias ebriensis (Pellegrin 1920) and Clarias anguillaris (Linnaeus 1758). Results: Results of osteological and morphometric analyses presented two members of Clarias genus ( C.gariepinus and C.anguillaris ) and a member of another genus ( H. longifilis ) to be closer in structural affinity than C. ebriensis despite the fact that C. ebriensis belong to the genus Clarias. These observed morphometric result support the basis for the earlier reported reproductive compatibility between H. longifilis and the large Clarias species ( C.gariepinus and C.anguillaris ). Discussion: The published karyological analysis of these species supports this view. These results therefore show a basal dichotomy between the two outgroups of one genus which is not related to their phyloyenetic origin. Similarity members of the large clarias have successfully been reported to undergo hybridization leading to the production of Heteroclarias and Clariabranchus, a situation probably suggestive of convergent evolution of the clariids at the genus level. Conclusion: It could safely be hypothesized that ecological adaptations of reproductive structures in H. longifilis and the large Clarias which is not related to their phylogenetic origin have given rise to this reproductive compatibility.

Phylogeny of Geophilomorpha (Chilopoda) inferred from new morphological and molecular evidence.

To address the phylogenetic relationships of the centipede order Geophilomorpha (more than 1000 species), we have reinterpreted and expanded the knowledge on their morphological disparity, and have doubled the amount of molecular data available. We performed maximum parsimony and maximum likelihood analyses, using 195 phylogenetically informative morphological characters for 80 species, and DNA sequences of 28S, 18S, 16S rRNA and COI for up to 48 species. We found strong support for the monophyly of Geophilomorpha, the basal dichotomy between Adesmata and Placodesmata=Mecistocephalidae, and the basal dichotomy within Adesmata between two clades that are recognized here as superfamilies Himantarioidea and Geophiloidea. With respect to the families currently in use, Himantarioidea comprises three well supported clades corresponding to (i) Oryidae, (ii) Himantariidae, and (iii) Schendylidae s.l. including Ballophilidae; Geophiloidea comprises another three supported clades corresponding to (iv) a new family Zelanophilidae, (v) Gonibregmatidae s.l. including Eriphantidae and Neogeophilidae, and (vi) Geophilidae s.l. including Aphilodontidae, Dignathodontidae, Linotaeniidae, and Macronicophilidae.

New information on amphibamids (Tetrapoda, Temnospondyli) from Richards Spur (Fort Sill), Oklahoma

ABSTRACT A nearly complete amphibamid skull from the Richards Spur locality in Oklahoma is demonstrated to be a new species of Tersomius. This new species has a mosaic of features seen in other amphibamids, and appears to fall on the Amphibamus side of the amphibamid basal dichotomy of some authors. This specimen also calls into question the validity of the Tersomius assignment of a large specimen from the Texas Red Beds. One feature of note is the presence of a weakly bicuspid fang on one of the vomers. This poorly developed feature is present only on an unattached replacement cusp, and appears to have been rapidly worn away through use. This is the first potential bicuspid palatal fang known from an amphibamid. A second partial skull is assigned to the recently described species Pasawioops mayi. A micro-computed tomographic reconstruction shows a prominent ventral flange of the nasal that meets a counterpart from the prefrontal and palatine to wall the nasal capsule posteriorly. The nasolacrimal canal shows the three openings in the orbit quickly converge to pass rostrally as a single canal except for a mysterious lateral diverticulation that has a superficial exposure on the lacrimal. Both skulls preserve a pars palatina of the premaxilla, in common with batrachians, and the Pasawioops specimen also preserves a prominent palatal process of the premaxilla, a frog synapomorphy. Richards Spur preserves one of the most diverse amphibamid faunas in the world, with three species described so far. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP

New insights into the intricate taxonomy and phylogeny of the Sylvia curruca complex

We use the mitochondrial cytochrome b from 213 individuals and the three nuclear introns BRM 15, myoglobin 2 and ODC 6–7 from a smaller subsample to evaluate the taxonomy of the Lesser Whitethroat Sylvia curruca (Aves, Passeriformes, Sylviidae) complex, which has long been controversial. We sequenced type material of the taxa althaea, blythi, margelanica and minula, and used topotypical material of caucasica, chuancheica, curruca and telengitica. The nuclear introns fail to resolve the complex, but cytochrome b recovers six major clades, revealing genetically identifiable populations corresponding to previously named taxa, and we propose that the names althaea, blythi, curruca, halimodendri, margelanica and minula, respectively, should be used for these. The margelanica clade is suggested to have a more extensive distribution than previously known, including both the taxon telengitica and a population in eastern Mongolia. The taxon minula is found to have a more restricted range than generally believed, only breeding in China. According to the mitochondrial gene tree, there is a basal dichotomy, with the taxa althaea, blythi, halimodendri and margelanica being part of one clade, well separated from a clade containing curruca and minula. Dating analysis suggests that a basal divergence separating curruca and minula from the other four taxa occurred between 4.2 and 7.2mya; these two then diverged between 2.3 and 4.4mya. The splits between the althaea, blythi, halimodendri and margelanica lineages is inferred to have occurred later, approximately between 1.0 and 2.5mya (all 95% HPD). The nucleotide data suggest significant departure from demographic equilibrium in blythi (clade 1a), halimodendri (clade 2a) and minula, whereas tendencies are weaker for other clades. We propose that the names althaea, blythi, curruca, halimodendri, margelanica and minula should be used for the major clades. However, whether these are treated as subspecies or species is largely a matter of species definition and is not resolved by our data.

High diversity of pancryptodiran turtles in the Lower Cretaceous of Europe

Turtles traditionally identified as basal Eucryptodira members were very abundant and diverse in the European Upper Jurassic. However, the European Cretaceous record of these turtles is poorly known. Brodiechelys brodiei, from the Wealden of the UK, is a turtle traditionally assigned to Eucryptodira. This taxon, recognized on the basis of very little material, has been poorly described and figured. More than a dozen shells are here attributed to B. brodiei. This allows a new diagnosis to be proposed for the taxon, and recognizes that their shells are subject to great intraspecific variability. This conclusion affects many characters used in the diagnosis of taxa defined by scarce material. The analysis of Hylaeochelys, a European Lower Cretaceous taxon traditionally identified as another basal Eucryptodira member, also allows high variability to be observed and several synonyms to be recognized. Hylaeochelys belli is identified here as the only valid species of this genus. Brodiechelys brodiei, H. belli and other European and Asian Jurassic and Lower Cretaceous taxa, previously identified as basal members of Eucryptodira, are incorporated into two hypotheses of phylogenetic relationships. A basal dichotomy in Pancryptodira is obtained. In one of the nodes, taxa traditionally assigned to Paracryptodira, Plesiochelyidae and H. belli are included. The other node groups B. brodiei, taxa traditionally assigned to “Xinjiangchelyidae”, and the Cryptodira members. This study shows a high diversity of Pancryptodira members in the Lower Cretaceous of Europe, assigned to several nodes. Representatives of Paracryptodira, other members of the node grouping the traditional members of Plesiochelyidae and Paracryptodira, and several members of the node grouping Xinjiangchelys latimarginalis and Cryptodira are identified.

Systematics of the subgenus of mouse opossums Marmosa (Micoureus) (Didelphimorphia, Didelphidae) with noteworthy records from Paraguay

The subgenus Marmosa (Micoureus) Lesson, 1842 includes six species of long-tailed, black masked mouse-opossums widely distributed in forested areas of the Neotropics from northern Argentina to Belize. Most of the nominal forms of Marmosa (Micoureus) have not been revised since 1933 and some currently accepted synonymies are in need of revision; similarly distributions of these forms remain for the most part unclear. Herein, we report Paraguayan new and noteworthy locality records for Marmosa (Micoureus), including the first records for the western Dry Chaco region. Specimens were identified to the species level on the basis of morphological and molecular data. In addition, we conducted a phylogenetic analysis that includes sequences of five of the six species currently recognized of Micoureus incorporating a total of 70 sequences of the subgenus. This constitute the most taxonomically and geographically dense phylogenetic analysis of Micoureus. Results show that the most basal dichotomy of the Micoureus clade does not delimit cis- and trans-Andean reciprocally monophyletic groups, rending the cis group paraphyletic to the single trans-species included, suggesting that the colonization of the western (trans) side of the Andes was a relatively late event in the biogeographic history of Micoureus. In addition, the phylogenetic analysis shows that additional taxonomic work is much needed to clarify the number of distinct biological units, either species or subspecies, within Micoureus.

Evolutionary history of mole rats (genus Nannospalax) inferred from mitochondrial cytochrome b sequence

Mole rats (genus Nannospalax) display prolific chromosomal variation with more than 50 distinct cytotypes. These cytotypes are largely indistinguishable morphologically, are mainly allopatric and their taxonomic ranking is contradictory. We established a cytochrome b phylogeny for 15 cytotypes belonging to all three species recognized on morphological grounds (morphospecies): N. leucodon, N. xanthodon and N. ehrenbergi. Phylogenetic reconstructions yielded two highly divergent groups which are in agreement with the current division into two subgenera (Nannospalax and Mesospalax). The former comprised samples from south-eastern Turkey, Israel and Egypt (the morphospecies N. ehrenbergi). Basal dichotomy within Mesospalax remained unresolved and the putative sister position of N. leucodon against the two lineages of N. xanthodon was not supported in our analysis. Net divergences between sister cytotypes were low (< 2.0%) and two N. leucodon cytotypes were not even reciprocally monophyletic. Among the three morphospecies, the genetic diversity was lowest in N. leucodon (2.4% ± 0.3%), highest in N. xanthodon (8.8% ± 0.7%) and intermediate in N. ehrenbergi (5.0% ± 0.5%). Our results show that associations between genetic and chromosomal variation are not widespread and common in mole rats, and therefore refute the generalization of a ‘cytotype-equals-species’ approach. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105, 446–455.