Combination Of Character States Research Articles

An updated infrageneric classification based on phylogenomics and character evolution in Hydrangea (Hydrangeaceae)

AbstractThe genus Hydrangea s.l. (Hydrangeaceae), a favorite among gardeners, comprises more than 80 species that are important understory plants in natural temperate and subtropical forests of the Northern Hemisphere. These species are hypervariable in morphology, especially in indumentum and floral characters, warranting a thorough exploration of the complex evolutionary history of morphological characters of the genus. Ideally, this is done within a robust phylogenetic framework with extensive taxon sampling. In this study, we propose a comprehensive taxonomic reassessment of Hydrangea based on a reconstruction of its molecular phylogeny based mainly on the chloroplast genome (plastome) and the most representative taxon sampling reported to date. Phylogenomic reconstruction yielded five well‐resolved major clades and three newly recognized subclades. Inspection of the 28 characters employed in traditional taxonomic revisions revealed homoplasy in many of these traits. Our results show that characters such as growth habit, woody stem type, number of enlarged marginal sepals, style and stamen number, fruit shape, and ovary position are useful for circumscribing infrageneric divisions. Unique synapomorphies are limited. For example, herb and subshrub growth habits are associated with all the species in H. sect. Deinanthe and sect. Cardiandra, respectively. Character state combinations are proposed for distinguishing infrageneric taxa. Based on a robust phylogenetic framework, our findings suggest a complex evolutionary history of Hydrangea morphological characters. Following the criterion of monophyly and considering the morphological consistency and synapomorphy of single and combined characters to diagnose relevant lineages, we update the classification of Hydrangea into 5 subgenera and 19 sections. Our proposed taxonomic scheme, based on a robust phylogenetic framework and in‐depth character study, provides an updated perspective on the infrageneric subdivision of Hydrangea s.l.

Revision of the Schistura cincticauda species group (Teleostei, Nemacheilidae) using molecular and morphological markers

To approach the taxonomy of large and complex animal groups it is of advantage to focus on species groups with shared derived character state. We investigate the composition, morphological characteristics and relationships of and within the Schistura cincticauda species group, whose members are small freshwater fishes that inhabit streams and rivers in eastern Myanmar and western and southern Thailand. A phylogenetic analysis using molecular genetic markers demonstrated the monophyly of this group; a combined genetic and morphological analysis revealed the inclusion of at least twelve species. They share the presence of a pair of black marks on the lower lip, one on each side of the median interruption (these marks may be reduced to few melanophores or even missing in some individuals). Additionally, all species share a small body size (max. 60 mm SL), an incomplete lateral line reaching at most to vertical through anal-fin base, and the absence of sexual dimorphism. Each of the 12 species is diagnosed by a unique combination of character states in fin ray numbers, anus position, presence/absence of an axillary pelvic lobe, and colour pattern. The distribution areas of several species overlap and five cases of syntopic occurrence are known. Five unnamed species are described herein.

Pollen morphology characterization of Dryades Groppo, Kallunki & Pirani, a new genus of Rutaceae, and its phylogenetically related species

Rutaceae (Sapindales) is represented by approximately 2040 species and 150–170 genera. Conchocarpus is the genus with the highest number of species and is circumscribed by a combination of character states, making it a polymorphic group. A recent study proposed a new genus, Dryades, formed by species formerly positioned in Conchocarpus. This study aims to describe the pollen morphology of Dryades species, comparing it with the palynology of phylogenetically related species, to present data that can characterize the species of Dryades. We analyzed the pollen grains of Dryades species and eight species of the genera Andreadoxa, Angostura, Erythrochiton, Galipea, Rauia and Conchocarpus. The pollen grains were acetolyzed, measured, described qualitatively, and analyzed quantitatively. Illustrations using light microscopy (LM) and scanning electron microscopy (SEM) are presented. Multivariate analysis was performed. The pollen grains are monads, isopolar, medium to very large in size, with subcircular to subtriangular amb, and oblate-spheroidal to prolate shape. The apertures are 3- or 5-colporate, varying in size (very small to very large colpi). The endoapertures are usually lalongate, rarely circular. The pollen grains analyzed are microreticulate, reticulate, macroreticulate, reticulate-baculate, baculate or verrucate-baculate. Both qualitative and quantitative characteristics of pollen grains proved to be important in distinguishing genera and grouping species within genera (in particular, the number of apertures, the length of the ectoaperture, the exine ornamentation and the size of the pollen grains). Dryades species show similarities in pollen morphology to species of related genera such as Andreodoxa, Galipea and especially Rauia. The shape of pollen grains and the number of apertures in Dryades are distinct from those found in Conchocarpus macrophyllus. The pollen data observed in this study confirm the pollen diversity of Rutaceae.

The femora of Drepanosauromorpha (Reptilia: Diapsida): Implications for the functional evolution of the thigh of Sauropsida.

The femora of diapsids have undergone morphological changes related to shifts in postural and locomotor modes, such as the transition from plesiomorphic amniote and diapsid taxa to the apomorphic conditions related to a more erect posture within Archosauriformes. One remarkable clade of Triassic diapsids is the chameleon-like Drepanosauromorpha. This group is known from numerous articulated but heavily compressed skeletons that have the potential to further inform early reptile femoral evolution. For the first time, we describe the three-dimensional osteology of the femora of Drepanosauromorpha, based on undistorted fossils from the Upper Triassic Chinle Formation and Dockum Group of North America. We identify apomorphies and a combination of character states that link these femora to those in crushed specimens of drepanosauromorphs and compare our sample with a range of amniote taxa. Several characteristics of drepanosauromorph femora, including a hemispherical proximal articular surface, prominent asymmetry in the proximodistal length of the tibial condyles, and a deep intercondylar sulcus, are plesiomorphies shared with early diapsids. The femora contrast with those of most diapsids in lacking a crest-like, distally tapering internal trochanter. They bear a ventrolaterally positioned tuberosity on the femoral shaft, resembling the fourth trochanter in Archosauriformes. The reduction of an internal trochanter parallels independent reductions in therapsids and archosauriforms. The presence of a ventrolaterally positioned trochanter is also similar to that of chameleonid squamates. Collectively, these features demonstrate a unique femoral morphology for drepanosauromorphs, and suggest an increased capacity for femoral adduction and protraction relative to most other Permo-Triassic diapsids.

New species of Tanaidacea from Cretaceous Kachin amber, with a brief review of the fossil record of tanaidacean crustaceans

Tanaidaceans are benthic, mostly marine, crustaceans that live burrowed in the substrate or in self-built tubes. The fossil record of Tanaidacea reaches back to the Carboniferous, 350 million years ago, but it is especially species-rich in Cretaceous amber sites from Spain and France. We report and formally describe a new species of Tanaidacea from 100-million-year-old Kachin amber, from the Hukawng Valley, Northern Myanmar, the first record of Cretaceous tanaidaceans outside Europe. The combination of character states of Tanaidaurum kachinensisgen. nov. et sp. nov. suggests that the new species is a representative of the early diversification of an unnamed group (Paratanaoidea+Tanaidoidea), an ingroup of the monophyletic group Tanaidomorpha. We briefly review the biased fossil record of Tanaidacea and present its abundance in European amber sites.

A NEW GENUS AND SPECIES MYCETINOPUS STRIATIPEDIS GEN. AND SP. N. (ACARI: ACARIDAE) ASSOCIATED WITH THE HANDSOME FUNGUS BEETLE MYCETINA MARGINALIS IN THE EASTERN PALEARCTIC

We describe unusual heteromorphic deutonymph of Mycetinopus striatipedis gen. and sp. n. (Acari: Acaridae) phoretic on the handsome fungus beetle Mycetina marginalis (Coleoptera, Endomychidae) in the Eastern Palearctic. These deutonymphs have a unique combination of character states that make them very distinct in the family Acaridae: an unpaired pigmented spot on the anterior propodosoma is present; supracoxal setae scx filiform and bifurcate; genu I with two solenidia; tibia-tarsi I–II are distinctly elongated and striated; vertical setae ve are present, and tarsal setae aa are lacking. Our work emphasizes the importance of continued exploration and documentation of the biodiversity of astigmatid mites associated with invertebrate hosts.

Three new species of Homatula (Teleostei: Nemacheilidae) from Yunnan, China, with comments on habitat conservation.

Based on the morphological comparisons and molecular results, three new species of Homatula, i.e., H. geminusclathratus sp. nov., H. microcephala sp. nov., and H. longibarbatus sp. nov., have been described and named from the Lancang-jiang (the upper Mekong River) and the Chuan-he (the upper Black River, a tributary of the Red River) basins. The loaches of Homatula from the Lancang-jiang and the Chuan-he can be distinguished via morphology, genetics, and geographic distribution. All of the 10 recorded species distributed in the Nu-jiang (the upper Salween River), the Lancang-jiang, and the upper Black River share the following combination of character states: whole body, except head, densely scaled; lateral line complete; and a short adipose crest along the dorsal midline of the caudal peduncle, anteriorly not reaching vertically through the anal-fin origin. Species with these characters are called the densely-scaled group of Homatula. The three newly described species belong to the densely-scaled group of Homatula. Based on molecular phylogenetics, these Homatula species form a monophyletic group that can be divided into two clades, the densely-scaled group and the non-densely-scaled group. The densely-scaled group of Homatula includes 13 species occurring between the Nu-jiang and the upper Black River. The non-densely-scaled group is non-monophyletic and includes 14 species that are distributed in the Red, Pearl, Yangtze, and Yellow River basins. Species of the non-densely-scaled group are clustered into four sub-clades that are constrained to the four river basins. Homatula exclusively inhabits mountain streams with rapid or gentle currents, vauclusian springs, underground rivers connected to streams, and ditches near villages and farmland. No specimens of Homatula were collected from the main streams of Lixian-jiang, Lancang-jiang, and Nu-jiang as well as their large tributaries. Small environmental changes in the habitat of Homatula, such as water pollution or extensive human use, can lead to species/population extinction. Effective conservation of rare and endemic fishes, like loaches of Homatula, entails systematic observations and more targeted protection.

A new ‘duck-billed’ dinosaur (Ornithischia: Hadrosauridae) from the upper Campanian of Texas points to a greater diversity of early hadrosaurid offshoots

We describe a previously unrecognized genus and species of basally-branching hadrosaurid dinosaur, Malefica deckerti, from the middle- to upper Campanian upper shale member of the Aguja Formation in Big Bend National Park, southwestern Texas, USA. This taxon is represented by a partial left maxilla. The hadrosaurid maxilla is particularly useful in differentiating species, and, despite the incomplete nature of the material, this new taxon is diagnosable by several autapomorphies and a unique combination of character states. Phylogenetic analysis places M. deckerti within Hadrosauridae but outside Saurolophidae, the major hadrosaurid clade consisting of the solid-crested or unadorned Saurolophinae and the hollow-crested Lambeosaurinae. When considered with the other known non-saurolophid hadrosaurids, this species adds to the growing evidence a hitherto unrecognized diversity of early hadrosaurid offshoots spanning the upper Santonian through the Maastrichtian and widespread throughout Eurasia and North America.

Taxonomy and distribution of the genus Santolina (Asteraceae) in Italy

The Santolina chamaecyparissus complex includes 13 species of dwarf aromatic evergreen shrubs from the western Mediterranean Basin. Five native species occurring in Italy are currently accepted. Four of them are endemic to relatively restricted areas in the peninsula, whereas S. corsica Jord. & Fourr. is endemic to Corsica and Sardinia. The taxonomic treatments of Italian Santolina have been changing significantly in the past, probably due to the misinterpretation of naturalised populations of S. chamaecyparissus, a widely cultivated pentaploid species, which occasionally escapes from cultivation through agamospermy or vegetative propagation. In this study, we carried out the first quantitative morphometric and comparative niche analyses concerning the four species endemic to continental Italy (S. etrusca, S. ligustica, S. neapolitana, and S. pinnata). Morphometric analyses (PCoA, Random Forest, and univariate analyses) show that these species can be easily distinguished by combinations of character states, whereas niche analyses (Schoener’s D and similarity test) suggest that they occur in distinct climatic conditions. Based on our results, we fully confirm the taxonomic distinctiveness of these species. An updated identification key, including all Santolina species occurring in Italy, is presented.&nbsp

A new early branching armored dinosaur from the Lower Jurassic of southwestern China.

The early evolutionary history of the armored dinosaurs (Thyreophora) is obscured by their patchily distributed fossil record and by conflicting views on the relationships of Early Jurassic taxa. Here, we describe an early diverging thyreophoran from the Lower Jurassic Fengjiahe Formation of Yunnan Province, China, on the basis of an associated partial skeleton that includes skull, axial, limb, and armor elements. It can be diagnosed as a new taxon based on numerous cranial and postcranial autapomorphies and is further distinguished from all other thyreophorans by a unique combination of character states. Although the robust postcranium is similar to that of more deeply nested ankylosaurs and stegosaurs, phylogenetic analysis recovers it as either the sister taxon of Emausaurus or of the clade Scelidosaurus+ Eurypoda. This new taxon, Yuxisaurus kopchicki, represents the first valid thyreophoran dinosaur to be described from the Early Jurassic of Asia and confirms the rapid geographic spread and diversification of the clade after its first appearance in the Hettangian. Its heavy build and distinctive armor also hint at previously unrealized morphological diversity early in the clade's history.

An enigmatic interstitial trichomycterine catfish from south-eastern Brazil found at about 1000 km away from its sister group (Siluriformes: Trichomycteridae)

During recent field studies in the upper Rio Paraná basin, south-eastern Brazil, a small undescribed trichomycterine catfish with interstitial habits was found. The combination of morphological character states exhibited by this species did not allow placement to any genus from eastern South America. A multigene phylogeny here performed strongly supported the new taxon as sister to Scleronema. Due to the confusing generic classification of the Trichomycterinae, the new taxon is formally placed in a new subgenus of Scleronema (Plesioscleronema subgen. nov.), instead of in a new monotypic genus. The inclusion of the new taxon in Scleronema implicated in a review of generic diagnostic morphological characters. Two apomorphic character states were found to be useful to diagnose Scleronema in this broader sense: presence of a skin flap on the posterior margin of the opercle and a unique frontal bone morphology. Scleronema auromaculatum spec. nov. differs from other trichomycterines by a unique morphology of the area involving the postero-dorsal portion of the quadrate and the adjacent region of the hyomandibula, the uroneural separated by the dorsal hypural plate by an interspace, and a widened hemal spine of the preural centre 2. The about 1000 km gap between the area where the new species was collected and the nearest collecting site of its sister group is probably a consequence of both anthropic environmental degradation and the specialised interstitial habits in this fish group, making it difficult to be found in ichthyological inventories.

A new species of Knodus (Characiformes: Characidae), with deep genetic divergence, from the Mearim and Munim river basins, Northeastern Brazil, and evidence for hidden diversity in adjacent river basins

Abstract A new species of Knodus from the Mearim and Munim River basins, Northeastern Brazil, is herein described based on integrative taxonomy, by using different molecular based species delimitation methods and independent approaches. The new species possesses the combination of character states that usually diagnoses the genus. The new species possesses a similar colour pattern to K. victoriae, which is also morphologically similar to it. The species described herein differs from K. victoriae by possessing more total vertebrae, more branched anal-fin rays, and fewer circumpeduncular scales. We also provide a detailed discussion of the morphological diagnostic features exhibited by Knodus species from adjacent river basins.

A sauropod from the Lower Jurassic La Quinta Formation (Dept. Cesar, Colombia) and the initial diversification of eusauropods at low latitudes

ABSTRACT The northern-most occurrence of Sauropoda in South America was collected in the 1940s from Early–Middle Jurassic-aged continental sediments on the western flank of the Serranía del Perijá in Colombia. Relocation of the site and re-preparation of the specimen, a well-preserved dorsal vertebra, provide important information about the initial diversification of sauropods at low latitudes. The specimen possesses autapomorphies and a unique combination of character states (e.g., divided centropostzygapophyseal lamina, strongly dorsally arched postzygapophyseal facets) that diagnose it as the new genus and species Perijasaurus lapaz. A medium-sized early eusauropod, Perijasaurus inhabited tropical lowland forested areas around the Toarcian–Aalenian boundary. Our phylogenetic analysis recovers Perijasaurus near the base of Eusauropoda, in an unresolved position near Cetiosaurus, Patagosaurus and kin (Bagualia, Spinophorosaurus, Nebulasaurus), and more deeply nested eusauropods. The phylogenetic position of Perijasaurus bolsters the idea that eusauropods achieved a broad geographic distribution during the Early–Middle Jurassic, before the deeper fragmentation of Pangea and after the Toarcian faunal turnover documented at high southern latitudes. Perijasaurus and other basally diverging sauropods display an intermediate level of bone weight reduction in the axial column that represents an antecedent to the more highly developed pneumatic system characterizing Neosauropoda.

Morphological and molecular evidence for the recognition of Caloglossa fonticola sp. nov. (Delesseriaceae, Rhodophyta) from an underground spring in Guangxi, China

Caloglossa (Ceramiales, Rhodophyta) is a globally distributed euryhaline red macroalgal genus. However, only a few Caloglossa species have been documented in permanent freshwater habitats. Here, a new Caloglossa species, Caloglossa fonticola sp. nov., is described and illustrated from an underground spring in Bama County, Guangxi, China, based on morphological observations and molecular phylogenetic analysis. The new species is morphologically distinguishable from other species in the genus by a unique combination of character states, including thallus internodal blades linear, hardly or slightly constricted at nodes, adventitious branches and endogenous branches both absent, and unicellular rhizoids forming from clusters of wing cells arising from the first three axial cells of the main axis and lateral axis. Phylogenetic analysis based on rbcL and LSU rRNA DNA sequences indicated that Caloglossa fonticola was nested in a well-supported clade with Caloglossa bengalensis (Bootstrap supports for ML/posterior probabilities for BI: rbcL-98/1.00, LSU-100/1.00), with high sequence divergence between these two species (8.2–8.4% for rbcL and 3.2% for LSU), supporting its specific status. This is the first species of the genus Caloglossa reported in spring water habitats. The description of C. fonticola expands the known diversity of Caloglossa.

A new candiru of the genus Paracanthopoma (Siluriformes: Trichomycteridae) from the Araguaia River basin, central Brazil.

A new species of the candiru genus Paracanthopoma is described from the floodplains of the Bananal Island, a transition area between the Cerrado and Amazon, in the Araguaia River basin, central Brazil. Paracanthopoma cangussu sp. nov. is distinguished from its congeners, Paracanthopoma parva and Paracanthopoma saci, by the presence of seven opercular odontodes, five dentary teeth, five median premaxillary teeth, and first dorsal-fin pterygiophore in a vertical through the centrum of the 23th or 24th vertebra. It is further distinguished from each congener by an exclusive combination of character states, comprising the number of vertebrae, number of precaudal vertebrae, number of dorsal procurrent caudal-fin rays, number of ventral procurrent caudal-fin rays, number of dorsal-fin rays, disposition of pores on the cephalic portion of the latero-sensory system, absence of an anterior process on the anterior margin of parieto-supraoccipital, number of dorsal-fin pteryigiophores and number of interopercular odontodes. Although vandelliines are known for being exclusively hematophagous, with guts gorged with blood, two cleared and stained specimens of P. cangussu sp. nov. had Chironomidae larvae (Insecta) on their guts. Because most specimens of P. cangussu sp. nov. were collected with stomachs filled with blood, it was hypothesized that the species feeds accidentally or occasionally on insects.

A comprehensive phylogeny of dwarf geckos of the genus Lygodactylus, with insights into their systematics and morphological variation

The 71 currently known species of dwarf geckos of the genus Lygodactylus are a clade of biogeographic interest due to their occurrence in continental Africa, Madagascar, and South America. Furthermore, because many species are morphologically cryptic, our knowledge of species-level diversity within this genus is incomplete, as indicated by numerous unnamed genetic lineages revealed in previous molecular studies. Here we provide an extensive multigene phylogeny covering 56 of the named Lygodactylus species, four named subspecies, and 34 candidate species of which 19 are newly identified in this study. Phylogenetic analyses, based on ∼10.1 kbp concatenated sequences of eight nuclear-encoded and five mitochondrial gene fragments, confirm the monophyly of 14 Lygodactylus species groups, arranged in four major clades. We recover two clades splitting from basal nodes, one comprising exclusively Malagasy species groups, and the other containing three clades. In the latter, there is a clade with only Madagascar species, which is followed by a clade containing three African and one South American species groups, and its sister clade containing six African and two Malagasy species groups. Relationships among species groups within these latter clades remain weakly supported. We reconstruct a Lygodactylus timetree based on a novel fossil-dated phylotranscriptomic tree of squamates, in which we included data from two newly sequenced Lygodactylus transcriptomes. We estimate the crown diversification of Lygodactylus started at 46 mya, and the dispersal of Lygodactylus among the main landmasses in the Oligocene and Miocene, 35–22 mya, but emphasize the wide confidence intervals of these estimates. The phylogeny suggests an initial out-of-Madagascar dispersal as most parsimonious, but accounting for poorly resolved nodes, an out-of-Africa scenario may only require one extra dispersal step. More accurate inferences into the biogeographic history of these geckos will likely require broader sampling of related genera and phylogenomic approaches to provide better topological support. A survey of morphological characters revealed that most of the major clades and species groups within Lygodactylus cannot be unambiguously characterized by external morphology alone, neither by unique character states nor by a diagnostic combination of character states. Thus, any future taxonomic work will likely benefit from integrative, phylogenomic approaches.

New specimens provide insights into the anatomy of the dinosauriform Lewisuchus admixtus Romer, 1972 from the upper Triassic levels of the Chañares Formation, NW Argentina.

Lewisuchus admixtus is an early dinosauriform described by Alfred Romer in 1972 on the basis of a single, incomplete skeleton, collected in lower Upper Triassic rocks of the renowned Chañares Formation, at the Los Chañares type-locality, La Rioja Province, north-western Argentina. Recent field explorations to the type-locality resulted in the discovery of two partial articulated skeletons, which provide significant novel information. The cranial bones, presacral series, femur, tibia, and proximal tarsals of the new specimens match the preserved overlapping anatomy of the holotype and previously referred specimens of L. admixtus, including the presence of unique combination of character states among dinosauriforms (anterior presacral column with additional ossification on the top of neural spines, dorsal neural spines fan-shaped, anterior surface of the astragalus with a dorsally curved groove, and an inflated area on the anterior portion of the medial surface of this bone). This new information improves our understanding of the anatomy and taxonomy of early dinosauriforms and reinforces the role of Argentinean beds on the study of the origin of dinosaurs.

A new short-faced archosauriform from the Upper Triassic Placerias/Downs\u2019 quarry complex, Arizona, USA, expands the morphological diversity of the Triassic archosauriform radiation

The Placerias/Downs’ Quarry complex in eastern Arizona, USA, is the most diverse Upper Triassic vertebrate locality known. We report a new short-faced archosauriform, Syntomiprosopus sucherorum gen. et sp. nov., represented by four incomplete mandibles, that expands that diversity with a morphology unique among Late Triassic archosauriforms. The most distinctive feature of Syntomiprosopus gen. nov. is its anteroposteriorly short, robust mandible with 3–4 anterior, a larger caniniform, and 1–3 “postcanine” alveoli. The size and shape of the alveoli and the preserved tips of replacement teeth preclude assignment to any taxon known only from teeth. Additional autapomorphies of S. sucherorum gen. et sp. nov. include a large fossa associated with the mandibular fenestra, an interdigitating suture of the surangular with the dentary, fine texture ornamenting the medial surface of the splenial, and a surangular ridge that completes a 90° arc. The external surfaces of the mandibles bear shallow, densely packed, irregular, fine pits and narrow, arcuate grooves. This combination of character states allows an archosauriform assignment; however, an associated and similarly sized braincase indicates that Syntomiprosopus n. gen. may represent previously unsampled disparity in early-diverging crocodylomorphs. The Placerias Quarry is Adamanian (Norian, maximum depositional age ~219 Ma), and this specimen appears to be an early example of shortening of the skull, which occurs later in diverse archosaur lineages, including the Late Cretaceous crocodyliform Simosuchus. This is another case where Triassic archosauriforms occupied morphospace converged upon by other archosaurs later in the Mesozoic and further demonstrates that even well-sampled localities can yield new taxa.

A new species of Brachychthoniidae (Acari: Oribatida) from the Eastern Central Alps (Austria, Tyrol), with the proposal of a new genus

A new species of the family Brachychthoniidae (Acari: Oribatida), Arcochthonius roynortoni n. sp., found on the summit of the Festkogel mountain (3030 m a.s.l.) in the Central Alps (Obergurgl, Tyrol, Austria), is described and illustrated, based on adults. Arcochthonius n. gen. is proposed for this species. The relationships to the closely related genus Synchthonius Hammen, 1952 and other genera of Brachychthoniidae are discussed. The new species is unique among Brachychthoniidae in having arched ridge-like sculpturing on thickened anterior edges of medial and posterior notogastral sclerites, and differs by a combination of morphological character states. Some notes on ecology and biology are given.

Evolution in the Genus Rhinella: A Total Evidence Phylogenetic Analysis of Neotropical True Toads (Anura: Bufonidae)

True toads of the genus Rhinella are among the most common and diverse group of Neotropical anurans. These toads are widely distributed throughout South America, inhabiting a great diversity of environments and ecoregions. Currently, however, the genus is defined solely on the basis of molecular characters, and it lacks a proper diagnosis. Although some phenetic species groups have traditionally been recognized within Rhinella, the monophyly of some of them have been rejected in previous phylogenetic analyses, and many species remain unassigned to these poorly defined groups. Additionally, the identity and taxonomy of several species are problematic and hinder the specific recognition and description of undescribed taxa. In this work, we first perform phylogenetic analyses of separate mitochondrial and nuclear datasets to test the possible occurrence of hybridization and/or genetic introgression in the genus. The comparative analysis of both datasets revealed unidirectional mitochondrial introgressions of an unknown parental species into R. horribilis (“ghost introgression”) and of R. dorbignyi into R. bernardoi; therefore, the mitochondrial and nuclear datasets of these species were considered separately in subsequent analyses. We performed total-evidence phylogenetic analyses that included revised molecular (four mitochondrial and five nuclear genes) and phenotypic (90 characters) datasets for 83 nominal species of Rhinella, plus several undescribed and problematic species and multiple outgroups. Results demonstrate that Rhinella was nonmonophyletic due to the position of R. ceratophrys, which was recovered as the sister taxon of Rhaebo nasicus with strong support. Among our outgroups, the strongly supported Anaxyrus + Incilius is the sister clade of all other species of Rhinella. Once R. ceratophrys is excluded, the genus Rhinella is monophyletic, well supported, and composed of two major clades. One of these is moderately supported and includes species of the former R. spinulosa Group (including R. gallardoi); the monophyletic R. granulosa, R. crucifer, and R. marina Groups; and a clade composed of the mitochondrial sequences of R. horribilis. The other major clade is strongly supported and composed of all the species from the non-monophyletic R. veraguensis and R. margaritifera Groups, the former R. acrolopha Group, and R. sternosignata. Consistent with these results, we define eight species groups of Rhinella that are mostly diagnosed by phenotypic synapomorphies in addition to a combination of morphological character states. Rhinella sternosignata is the only species that remains unassigned to any group. We also synonymize nine species, treat three former subspecies as full species, and suggest that 15 lineages represent putative undescribed species. Lastly, we discuss the apparently frequent occurrence of hybridization, deep mitochondrial divergence, and “ghost introgression”; the incomplete phenotypic evidence (including putative character systems that could be used for future phylogenetic analyses); and the validity of the known fossil record of Rhinella as a source of calibration points for divergence dating analyses.