Molecular diversification of salamanders of the tropical American genus Bolitoglossa (Caudata: Plethodontidae) and its evolutionary and biogeographical implications

The largest genus of salamanders, Bolitoglossa (Plethodontidae), is widespread in tropical America, where it occurs in diverse habitats and elevations, from high elevation grasslands to lowland rain forest . It has the most extensive geographical range of any salamander genus. While most species occur in Middle America, it ranges throughout most of tropical South America as well. Phylogenetic analysis of 1196 bp of two mitochondrial genes (cytochrome b , 16S RNA) from 55 species offers strong support for the monophyly of the genus and sorts the species into a number of clades. Taking into account morphology, distribution, general ecology, and prior systematic and taxonomic studies, we recognize seven subgenera, four of them new: Bolitoglossa Duméril, Bibron et Duméril, 1854, Eladinea Miranda Ribeiro, 1937, Magnadigita Taylor, 1944, Mayamandra , Nanotriton , Oaxakia and Pachymandra . All South American and some lower Middle American species are included in a single well -supported clade, Eladinea . At the species level our analyses uncover the existence of large genetic diversity within morphologically homogeneous taxa. We propose the new combination: B. (Eladinea) paraensis (Unterstein, 1930) stat. nov. , for Brazilian salamanders previously included under B. altamazonica . We evaluate evidence for the multiple colonization of the tropical lowlands by morphologically derived species groups. South America was invaded by members of one clade, Eladinea , which we infer to have dispersed to South America prior to closure of the Panamanian Portal. Despite the relatively long history of salamanders in South America, that continent now accounts for a relatively small proportion of the lineages and species of neotropical salamanders.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society, 2004, 81 , 325–346.     

Miniaturization and its effects on cranial morphology in plethodontid salamanders, genus Thorius (Amphibia: Plethodontidae). I. Osteological variation

Cranial skeletal morphology, ontogeny and variation are examined in five species of Thorius , a genus of diminutive plethodontid salamanders that are among the smallest, extant, tailed tetrapods. The skull of adull Thorius is characterized by: (1) limited development or absence of several ossified elements and dentition; (2) increased inter-and intraspecific variability; (3) novel morphological configurations of the braincase and jaw suspensorium. Posthatching cranial mineralization in all species of Thorius is truncated precociously with respect to that typical of larger and more generalized plethodontid genera, such as Pseudoeurycea. These features implicate paedomorphosis as a predominant mechanism responsible for the evolution of decreased size in Thorius from larger plethodontid ancestors. Interspecific differences in cranial morphology are evident; species may be characterized by greater or lesser degrees of truncated development. However, there is no consistent relationship between degree of paedomorphosis and mean adult body size in interspecific comparisons. Adult morphology of several individual elements represent potentially useful taxonomic characters for distinguishing species.
Reduction, increased variability, and morphological novelty are common to many lineages of dwarfed taxa. They represent a null hypothesis for examination of the developmental mechanisms and morphological consequences of miniaturization in other groups.     

Sperm aggregations in the spermatheca of female desmognathine salamanders (Amphibia: Urodela: Plethodontidae)

The alignment of sperm in a cloacal sperm storage gland, the spermatheca, was studied in female desmognathine salamanders by scanning and transmission electron microscopy. Females representing nine species and collected in spring, late summer, and fall in the southern Appalachian Mountains contained abundant sperm in their spermathecae. The spermatheca is a compound tubuloalveolar gland connected by a single common tube to the middorsal wall of the cloaca. Sperm enter the common tube in small groups aligned in parallel along their axes, and continue in a straight course until encountering divisions of the common tube (neck tubules) or luminal borders of distal bulbs, which can act as barriers. Sperm may form tangles, in which small clusters retain their mutual alignment, at the branches of the neck tubules from the common tube, or in the lumen of the distal bulbs, where subsequent waves of sperm collide with sperm already present. The nuclei of some sperm from the initial group to encounter the walls of the distal bulbs appear to become embedded in secretory material on the luminal border or in the apical cytoplasm of the spermathecal epithelial cells. We propose that these sperm become trapped in the spermatheca and are ultimately degraded. J. Morphol. 238:143–155, 1998. © 1998 Wiley-Liss, Inc.     

Appendicular skeletal morphology in minute salamanders,genus Thorius (amphibia: Plethodontidae): Growth regulation,adult size determination,and natural variation

Patterns of growth and variation of the appendicular skeleton were examined in Thorius, a speciose genus of minute terrestrial plethodontid salamanders from southern Mexico. Observations were based primarily on ontogenetic series of each of five species that collectively span the range of adult body size in the genus; samples of adults of each of seven additional species provided supplemental estimates of the full range of variation of limb skeletal morphology. Limbs are generally reduced, i.e., pedomorphic, in both overall size and development, and they are characterized by a pattern of extreme variation in the composition of the limb skeleton, especially mesopodial elements, both within and between species. Fifteen different combinations of fused carpal or tarsal elements are variably present in the genus, producing at least 18 different overall carpal or tarsal arrangements, many of which occur in no other plethodontid genus. As many as four carpal or tarsal arrangements were observed in single population samples of each of several; five tarsal arrangements were observed in one population of T. minutissimus. Left-right asymmetry of mesopodial arrangement in a given specimen is also common. In contrast, several unique, nonpedomorphic features of the limb skeleton, including ossification of the typically cartilaginous adult mesopodial elements and ontogenetic increase in the degree of ossification of long bones, are characteristic of all species and distinguish Thorius from most related genera. They form part of a mechanism of determinate skeletal growth that restricts skeletal growth after sexual maturity. Interspecific differences in the timing of the processes of appendicular skeletal maturation relative to body size are well correlated with interspecific differences in mean adult size and size at sexual maturity, suggesting that shifts in the timing of skeletal maturation provide a mechanism of achieving adult size differentiation among species. Processes of skeletal maturation that confer determinate skeletal growth in Thorius are analogous to those typical of most amniotes – both groups exhibit ontogenetic reduction and eventual disappearance of the complex of stratified layers of proliferating and maturing cartilage in long bone epiphyses – but, unlike most amniotes, Thorius lacks secondary ossification centers. Thus, the presence of secondary ossification centers cannot be used as a criterion for establishing determinate skeletal growth in all vertebrates.     

The colubrid radiation in Africa (Serpentes: Golubridae): phylogenetic relationships and evolutionary patterns based on immunological data

Phylogenetic relationships among genera of African colubrids were evaluated using estimates of divergence among serum albumins compared by microcomplement fixation. Representatives of about half of the extant genera of African colubrids, as well as the Elapidae, Atractaspis and the Madagascan colubrid Leioheterodon, were analysed. The tree of best fit to the data has an unresolved basal polychotomy comprising at least five lineages of colubrids, as well as Elapidae and Atractaspis; thus, colubrids were not demonstrably monophyletic with these data. Two cosmopolitan clades, colubrines and natricines, are represented in Africa by series of closely related genera, but divergence among other genera is relatively great. Rate tests show that this is apparently not due to higher rates of albumin evolution in these, relative to other colubrids. Among the other associations supported by the immunological data are: (1) Psammophis-(Rhamphiophis-Dipsina)-Malpolon-Psammophylax; (2) Amblyodipsas-Macrelaps; (3) (Lycodonomorphus-Lamprophis)-Mehelya; and (4) Colubrinae-Natricinae. Grayia is questionably associated with the colubrine-natricine lineage. Prosymna and Lycodon are clearly members of the colubrine clade, and Amplorhinus possibly associates with Leioheterodon. Gonionotophis, Duherria, Lycophidion and Pseudaspis show no strong association with any other genera, and represent other basal or near-basal clades within the colubrid/elapid radiation. The immunological data do not support a clade comprising the Elapidae, Atractaspis and some ‘aparallactines’ relative to Viperidae and other colubrids. The basal colubrid-elapid-Atractaspis divergence occurred more than 30 Myr ago, and the fossil record of colubrids in Africa greatly underestimates both the age and clade diversity of this group. In contrast to the pattern of radiation in the neotropics, where most colubrids belong to one of three major clades, in Africa only the colubrine lineage comprises a substantial portion of the extant generic diversity; most other genera stem from relatively ancient cladogenetic events and have few living representatives.     

Falling apart and merging: diversification of slender salamanders (Plethodontidae: Batrachoseps) in the American West

The plethodontid genus Batrachoseps , the slender salamanders, is the most diverse clade of salamanders in western North America, but it has posed taxonomic difficulties because it contains many morphologically cryptic species. A segment of the mitochondrial DNA gene cytochrome b was studied for 278 individuals densely sampled from throughout the range of all 18 described species and several undescribed species. Phylogenetic analyses of the mtDNA data identify six major clades, one corresponding to the subgenus Plethopsis and five within a monophyletic subgenus Batrachoseps. All major clades and most species within these clades display strong phylogeographic structuring. Comparisons of mtDNA and allozyme data show that several allozymically cohesive groups are not monophyletic with respect to mtDNA. We suggest that this phenomenon results from fragmentation of populations, divergence in allopatry, and then recontact and gradual merging of units caused predominantly by male-mediated gene flow. The mtDNA offers evidence that populations were once more isolated than they are now, while the patterns of allozyme variation reflect recent and current interactions among populations. The complex patterns of morphological, allozymic and mtDNA variation associated with the constantly changing geological landscape give insight into the nature of processes responsible for species formation in Batrachoseps .  © 2002 The Linnean Society of London. Biological Journal of the Linnean Society , 2002, 76 , 361–391.     

A new genus and species of lungless salamander (family Plethodontidae) from the Appalachian highlands of the south-eastern United States

We describe a striking new species of the lungless salamander family Plethodontidae from the Appalachian foothills of northern Georgia, USA. This miniature species, c . 25–26 mm (adult standard length), is so distinctive genetically and morphologically that we erect a new genus, the first new genus of amphibian described from the US in nearly 50 years. It is unique among plethodontids from eastern North America in displaying sexual colour dimorphism. Although certain miniaturized plethodontids exhibit a reduced number (four) of digits on the pes, this species possesses a full complement of five toes. A plethodontid phylogeny derived from mitochondrial and nuclear DNA sequences places it in the tribe Spelerpini as the sister taxon to Eurycea . Genetic divergence between the new species and Eurycea for the nuclear gene Rag -1 (4.7%) is among the higher levels observed between long-established spelerpine genera (2.6–5.3%). This new form appears to be rare and is of immediate conservation concern.     

Phylogenetic analysis of the Mexican freshwater crabs of the tribe Pseudothelphusini (Decapoda: Brachyura: Pseudothelphusidae)

The Mexican pseudothelphusid crabs are classified in one subfamily, three tribes, and 13 genera. Up to now, 56 species have been recognized, distributed in a strictly Neotropical pattern, with some of them reaching the state of Sonora on the western slope of Mexico. The tribe Pseudothelphusini is the most diverse, with five genera and 35 species, all of them endemic to Mexico: the two most species‐rich genera are Pseudothelphusa, with 23 species, and Tehuana, with eight species; Epithelphusa includes two species, whereas Disparithelphusa and Smalleyus are monotypic. The Pseudothelphusini lack an updated systematic revision, which could serve as a framework to analyse the monophyletic origin of the group, to clarify the relationships among genera and species, as well as to resolve the taxonomic status of various species complexes. In the present study, an exhaustive morphological revision was conducted using somatic and sexual characters. A phylogenetic analysis was performed using 77 characters and 183 character states, taken from 41 species. Ten trees of the same length were obtained using PAUP 4.0 through a heuristic search. The results show that the tribe as it is actually known constitutes a paraphyletic group, in which the species of Epithelphusa and Pseudothelphusa puntarenas are excluded from the internal group. According to the obtained results, the tribe Pseudothelphusini s.s. includes five genera: Smalleyus, Pseudothelphusa, Tehuana, and two new ones to accommodate Pseudothelphusa galloi and Pseudothelphusa sulcifrons, respectively. This new arrangement considers the provisional suppression of the genus Disparithelphusa, which remained as another species of Pseudothelphusa throughout the cladistic analysis. The phylogenetic results show a strong congruence with the distribution of the species, in several cases grouping species that form morphological clines along a geographical gradient. The previously proposed southern origin of the tribe Pseudothelphusini gains support with the results obtained. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 160 , 457–481     

Adaptive radiations in butterflies: evolutionary history of the genus Erebia (Nymphalidae: Satyrinae)

We studied the speciose butterfly genus Erebia by reconstructing its phylogenetic relationships using parsimony and Bayesian approaches. We estimated times and rates of diversification for its lineages and employed a biogeographical analysis in order to reconstruct its evolutionary history. DNA sequence data from one mitochondrial gene and three nuclear genes were analyzed for a total of 74 species in Erebia. The estimated dates of origin and diversification for clades, in combination with a biogeographical analysis, suggest that the genus originated in Asian Russia and started its diversification process around 23 Myr. An important event was the dispersal of a lineage from Asia to Western Europe between 23 and 17 Myr, which allowed the radiation of most of species in the genus. The diversification pattern is consistent with a model of diversity limited by clade richness, which implies an early rapid diversification followed by deceleration due to a decrease in speciation. We argue that these characteristics of the evolutionary history of Erebia are consistent with a density‐dependent scenario, with species radiation limited by filling of niche space and reduced resources. We found that the Boeberia parmenio appears strongly supported in the genus Erebia and therefore we place Boeberia Prout, 1901 as a junior synonym of Erebia Dalman, 1816 ( syn. nov. ).     

Histology of mental and caudal courtship glands in three genera of plethodontid salamanders (Amphibia: Plethodontidae)

Salamanders in the family Plethodontidae exhibit a unique tail‐straddle walk during courtship that can include the use of sexually dimorphic mental and caudal courtship glands. This study presents novel histological and fine structure data on mental glands and caudal courtship glands in Plethodon mississippi, Desmognathus conanti and Eurycea quadridigitata using both light microscopy and scanning electron microscopy. This study represents the first use of scanning electron microscopy to observe these glands. Both mental and caudal courtship glands were observed to vary seasonally in gland diameter and histology according to the breeding season of each species. Morphological variation was observed across the three species studied in both clustering and relative size of the glands compared to neighbouring mucous and granular glands. Hypertrophied mental glands are larger than mucous or granular glands in all species, but relationships among caudal courtship glands and other skin glands vary among species. In E. quadridigitata, active caudal courtship glands are larger than mucous and granular glands, but in D. conanti, caudal courtship glands are similar in size to granular glands and larger than mucous glands. In P. mississippi, caudal courtship glands are scattered among significantly larger granular glands and are similar in size to mucous glands.     

Ecnomus of Madagascar,species without modified spur (Trichoptera: Ecnomidae)

The 11 Malagasy species of the genus Ecnomus McLachlan, 1864 that do not belong to the psychomyiellodes species group are studied. One of them (Ecnomus salgiel Malicky, 2015) was recently described from Nosy Be Island. Ten are new and described: Ecnomus felix n. sp., E. dobignyi n. sp., E. matsaboryi n. sp., E. granjoni n. sp., E. commersoni n. sp., E. menavavae n. sp., E. ikopaensis n. sp., E. rubermortis n. sp., E. evidens n. sp., and E. tendroensis n. sp. All are endemic to Madagascar. Their distributions on the island are briefly described according to ecological data.     

Comparative skull osteology of Karsenia koreana (Amphibia,Caudata, Plethodontidae)

The recent discovery of a plethodontid salamander, Karsenia koreana, in Korea challenged our understanding of the biogeographic history of the family Plethodontidae, by far the largest family of salamanders, which otherwise is distributed in the New World with a few European species. Molecular studies suggest that Karsenia forms a clade with Hydromantes (sensu lato), which includes among its species the only other Old World plethodontids. We studied the skull of K. koreana and compared it with that of other plethodontid genera, especially members of the subfamily Plethodontinae, which it resembles most closely in general anatomy. The anatomy of its skull corresponds to the most generalized and apparently ancestral condition for plethodontids. No clearly autapomorphic states were detected, and no synapomorphies can be found that would link it to other genera. The Karsenia skull is cylindrical and well ossified, giving an impression of strength. In contrast, the skull of Hydromantes is highly derived; the skull is flattened and the bones are weakly ossified and articulated. Hydromantes and Karsenia share no unique anatomical features; differences between them are especially evident in the hyobranchial skeleton, which is generalized in Karsenia but highly modified in Hydromantes, which is well known for its highly projectile tongue. Plethodon and Plethodon‐like species, including Karsenia and to a lesser degree Ensatina, represent the more generalized and apparently ancestral plethodontid morphology. Specialized morphologies have evolved along only a few morphological axes within the Plethodontidae, resulting in a pattern of rampant homoplasy. Our analysis of the anatomy of the new Asiatic lineage illuminates some potential mechanisms underlying adaptive morphological evolution within the Plethodontidae. J. Morphol. 2010. © 2009 Wiley‐Liss, Inc.     

Biogeography and evolution of Central American cloud forest salamanders (Caudata: Plethodontidae: Cryptotriton), with the description of a new species

The cloud forests of Mesoamerica are notable for their high endemism, and plethodontid salamanders provide a striking example of divergence and microendemism across cloud forest blocks at a regional level. Salamanders that make use of arboreal bromeliad microhabitats in the cloud forest appear to be especially prone to divergence driven by natural habitat fragmentation, and are expected to show high endemism at small spatial scales. We use a multilocus dataset to investigate the biogeographic history and relationships among species of a small genus of salamander, Cryptotriton, restricted to the cloud forests of Nuclear Central America. We use a morphological data set along with a coalescent species delimitation method to reveal the presence of at least one undescribed species from an isolated cloud forest in eastern Guatemala. Biogeographic analyses show that Cryptotriton has a different biogeographic history than another clade of cloud forest‐restricted salamanders in the same region, perhaps indicating that each genus restricted the spatial expansion and diversification of the other through preemptive occupancy. Our results suggest that isolation across relatively short geographic distances has led to range fragmentation and deep divergence between species. Exploration of remaining patches of cloud forest likely will continue to reveal undetected diversity. © 2015 The Linnean Society of London     

Monograph of Carex section Schiedeanae (Cyperaceae): Unexpected taxonomic and ecological diversity in a Mexican sedge clade

Carex section Schiedeanae (subg. Euthyceras) has long been thought to comprise at most five species of Mexican sedges. Our morphological studies in the field and herbarium, however, supported by more recent DNA sequencing work, demonstrate that the section is, in fact, three times as species-rich, making it one of the largest sections in Mexico. Its 15 species range from Chihuahua to Tamaulipas south to Veracruz and Oaxaca; a single species, Carex muriculata, extends into the United States. The section has unusual inflorescences with simple (except in Carex complexa), uniformly androgynous, sessile spikes, utriculiform cladoprophylls, and perigynia with a unique combination of pubescence types composed of papillae; unicellular, simple hairs; and (in many species) multicellular tubercles. We recognize five previously described species (C. muriculata,Carex perstricta,Carex schiedeana, Carex stellata, and Carex vizarronensis) and describe 10 additional species (Carex angustilepis, Carex cabralii, Carex complexa, Carex dentata, Carex gypsophila, Carex mesophila, Carex paneroi, Carex planilamina, Carex revoluta, and Carex tehuacana). We have expanded the morphological features used in the section to include particularly anther, staminate scale, and style features, and more detailed micromorphology of the perigynia, especially indumentum. In total, 13 of the 15 species recognized herein, with a total of 32 individuals, were examined for ETS and ITS for phylogenetic reconstruction. Phylogenetically, the xeric species (plus C. paneroi) form a grade leading to a clade of the more mesophytic species adapted to forest understories, plus the unique cliff dwelling C. complexa.     

The cranial morphology of Greererpeton burkemorani Romer (Amphibia: Temnospondyli)

The skull of Greererpeton burkemorani Romer, a temnospondyl amphibian from the Upper Mississippian at Greer, West Virginia is described. A detailed account of the stapes of a Mississippian amphibian is given for the first time and its function is discussed. It is suggested that the stapes formed the principal element of support for the back of the braincase and resisted potential dislocation of the otico-occipital region from the skull roof during contraction of the hypaxial musculature.
Greererpeton is included in the Colosteidae and an amended diagnosis of the family is given. Erpetosaurus differs from Colosteus, Greererpeton and Pholidogaster in the pattern of bones in the skull roof and palate, the dentition and the otic region and, consequently, it is removed from the Colosteidae. The Temnospondyli are considered to be a monophyletic group characterized by the development of a connection between the dorsal portion of the occipital arch, the exoccipital bones, and the skull roof. The loxommatids are removed from the Temnospondyli as they retain the plesiomorphic condition of braincase attachment which relies exclusively on derivatives of the auditory capsules.
On the basis of similarities in the structure of the braincase, palate and manus it is suggested that microsaurs are the collateral descendants (sister group) of temnospondyls. This relationship may account for the large number of similarities in the three living groups of Amphibia: Anura are generally believed to have descended from temnospondyls, while the Urodela and Apoda are often considered to have descended from microsaurs. These systematic conclusions endorse the recent suggestions that neither the Lepospondyli nor the Labyrinthodontia are natural groups, and both terms should be abandoned.     

Molecular data illuminate cryptic nudibranch species: the evolution of the Scyllaeidae (Nudibranchia: Dendronotina) with a revision of Notobryon

Scyllaeidae represents a small clade of dendronotoid nudibranchs. Notobryon wardi Odhner, 1936, has been reported to occur in tropical oceans from the Indo‐Pacific and eastern Pacific to temperate South Africa. The systematics of Notobryon has not been reviewed using modern systematic tools. Here, specimens of Notobryon were examined from the eastern Pacific, the Indo‐Pacific, and from temperate South Africa. Additionally, representatives of Scyllaea and Crosslandia were studied. Scyllaeidae was found to be monophyletic. Notobryon was also found to be monophyletic and is the sister group to Crosslandia plus Scyllaea. The molecular data also clearly indicate that within Notobryon, at least three distinct species are present, two of which are here described. Genetic distance data indicate that eastern Pacific and South African exemplars are 10–23% divergent from Indo‐Pacific exemplars of Notobryon wardi. Scyllaea pelagica has been regarded as a single, circumtropical species. Our molecular studies clearly indicate that the Atlantic and Indo‐Pacific populations are distinct and we resurrect Scyllaea fulva Quoy & Gaimard, 1824 for the Indo‐Pacific species. Our morphological studies clearly corroborate our molecular findings and differences in morphology distinguish closely related species. Different species clearly have distinct penial morphology. These studies clearly reinforce the view that eastern Pacific, Indo‐Pacific, and temperate biotas consist largely of distinct faunas, with only a minor degree of faunal overlap. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 165 , 311–336.