Premaxillary Teeth Research Articles

Cranial anatomy of the basal neoceratopsian Auroraceratops rugosus (Ornithischia: Ceratopsia) from the Yujingzi Basin, Gansu Province, China

ABSTRACTThe basal neoceratopsian dinosaur Auroraceratops rugosus was described based on a single skull from the Gongpoquan Basin in northwestern Gansu Province, China. The genus is now known from over 80 specimens, including many from the neighboring Yujingzi Basin. Auroraceratops is one of the best-known basal neoceratopsians. Auroraceratops can be diagnosed by the following autapomorphies: inflated premaxillary teeth; a fungiform expansion of the lacrimal; large tuber caudodorsally on the dentary near the contact with the surangular; and tubercle on the lateral face of the dentary at about the middle of the mandible. Auroraceratops also has a combination of plesiomorphic and derived characters. It possesses characters plesiomorphic to Neoceratopsia, such as broad nasals (seen in basal ceratopsians, such as Yinlong), the absence of a lateral ridge on the surangular, a relatively high number of premaxillary teeth (three), and rugosity on the dentary, jugal, surangular, and sometimes the postorbital, which is in detail similar to that seen in chaoyangsaurids. At the same time, Auroraceratops possesses derived characters not seen in Liaoceratops, the earliest diverging member of Neoceratopsia. These features include an epijugal and a surangular wall lateral to the mandibular glenoid fossa. The cranial anatomy of the early horned dinosaur Auroraceratops rugosus is described.Citation for this article: Morschhauser, E. M., D. Li, H. You, and P. Dodson. 2019. Cranial anatomy of the basal neoceratopsian Auroraceratops rugosus (Ornithischia: Ceratopsia) from the Yujingzi Basin, Gansu Province, China; pp. 36–68 in Hailu You, Peter Dodson, and Eric Morschhauser (eds.), Auroraceratops rugosus (Ornithischia, Ceratopsia) from the Early Cretaceous of northwestern Gansu Province, China. Society of Vertebrate Paleontology Memoir 18. Journal of Vertebrate Paleontology 38(Supplement). DOI: 10.1080/02724634.2017.1399136.

A New Species ofCurculionichthys(Siluriformes: Hypoptopomatinae) from the Western Border of the Brazilian Shield, Madeira River Basin, Brazil

Curculionichthys scaius, new species, is distinguished from other congeners by having two usually conspicuous, somewhat triangular dark brown speckles lateral to the anal-fin origin, a pointed snout with paired rostral plates, numerous lateral abdominal plates, a single series of large median abdominal plates, numerous dentary and premaxillary teeth, and several morphometric proportions of the body and head, mostly involving prepelvic, prepectoral, and preanal distances, head and cleithral width, caudal peduncle length, and dorsal-fin spine. The new species represents the first record of the genus Curculionichthys in the Madeira River basin and is the most westerly distribution in the Amazon.

A New Species ofSpatuloricariaSchultz, 1944 (Siluriformes: Loricariidae), from the Orinoco River Basin, Colombia

A new species of Spatuloricaria is described from the Orinoco River basin, Colombia. The new species can be distinguished from its congeners by the following characters: a broad, dark brown stripe on the first pre-dorsal plate, which occupies the entire plate, reaching the preopercle, and sometimes reaching the second pre-dorsal plate; the possession of a small group of plates posterior to the urogenital pore; the abdominal surface with scattered, very small plates leaving naked areas; the possession of five transverse dark brown bands on the dorsal region; and four to five premaxillary teeth. The new species is the first valid species of Spatuloricaria distributed in the Orinoco River basin. Ecological notes of the species and comments regarding the taxonomy and phylogenetic relationships of the genus are offered.

A new microvertebrate assemblage from the Mussentuchit Member, Cedar Mountain Formation: insights into the paleobiodiversity and paleobiogeography of early Late Cretaceous ecosystems in western North America.

The vertebrate fauna of the Late Cretaceous Mussentuchit Member of the Cedar Mountain Formation has been studied for nearly three decades, yet the fossil-rich unit continues to produce new information about life in western North America approximately 97 million years ago. Here we report on the composition of the Cliffs of Insanity (COI) microvertebrate locality, a newly sampled site containing perhaps one of the densest concentrations of microvertebrate fossils yet discovered in the Mussentuchit Member. The COI locality preserves osteichthyan, lissamphibian, testudinatan, mesoeucrocodylian, dinosaurian, metatherian, and trace fossil remains and is among the most taxonomically rich microvertebrate localities in the Mussentuchit Member. To better refine taxonomic identifications of isolated theropod dinosaur teeth, we used quantitative analyses of taxonomically comprehensive databases of theropod tooth measurements, adding new data on theropod tooth morphodiversity in this poorly understood interval. We further provide the first descriptions of tyrannosauroid premaxillary teeth and document the earliest North American record of adocid remains, extending the appearance of this ancestrally Asian clade by 5 million years in western North America and supporting studies of pre-Cenomaninan Laurasian faunal exchange across Beringia. The overabundance of mesoeucrocodylian remains at the COI locality produces a comparatively low measure of relative biodiversity when compared to other microvertebrate sites in the Mussentuchit Member using both raw and subsampling methods. Much more microvertebrate research is necessary to understand the roles of changing ecology and taphonomy that may be linked to transgression of the Western Interior Seaway or microhabitat variation.

A new species of Coloborhynchus (Pterosauria, Ornithocheiridae) from the mid-Cretaceous of North Africa

Pterosaur faunas experienced dramatic turnover between the Early and Late Cretaceous, but fossils documenting this transition are rare. The mid-Cretaceous Kem Kem beds of Morocco are one of a handful of localities preserving pterosaurs from this important interval. Previously reported taxa from the Kem Kem beds include the ornithocheirid Siroccopteryx moroccensis, the azhdarchoids Alanqa saharica and Xericeps curvirostris, an unnamed tapejarid, and a putative pteranodontid. Here, a new species of ornithocheirid, Coloborhynchus fluviferox sp. nov., is described on the basis of a well-preserved anterior rostrum fragment. It is assigned to Coloborhynchus based on the presence of an anteriorly directed first tooth pair protruding from a palatal surface, which is deflected dorsally by 90°. The new specimen differs from Siroccopteryx moroccensis and is distinguished from other species of Coloborhynchus by numerous characters, including an anterior palatal surface that defines a high isosceles triangle with two shallow, subcircular depressions located dorsal to premaxillary tooth pair one. The central region of alveoli for the first tooth pair is level with the dorsal borders of the second tooth pair and the mediodorsal crest rises steeply forming a blunt termination of the rostrum. The new species brings the number of pterosaur species from the Kem Kem beds to at least 5. The Kem Kem pterosaur assemblage resembles other Early Cretaceous faunas in having a high diversity of toothed forms, but also resembles latest Cretaceous faunas in having several edentulous azhdarchoids.

Reassessment of the Styxosaurus snowii (Williston, 1890) holotype specimen and its implications for elasmosaurid plesiosaurian interrelationships

The holotype (KUVP 1301) of Styxosaurus snowii—one of the earliest described elasmosaurid plesiosaurians—consists of a well-preserved cranium, mandible and articulated sequence of anterior–mid-series cervical vertebrae found in the lowermost Campanian strata of the Smoky Hill Chalk Member in the Niobrara Formation of Kansas, USA. This particular specimen has proven important for recent phylogenies of Elasmosauridae, and is integral to resulting definitions of the subfamily-level clade, Styxosaurinae. Despite this, KUVP 1301 has not been redescribed or figured in detail since its original taxonomic establishment. We, therefore, re-evaluated KUVP 1301 and assessed its phylogenetic implications. Several notable character states are pertinent for diagnosing S. snowii at genus and species level: (1) an anisodont functional dentition comprising enlarged premaxillary and dentary teeth with a pair of maxillary ‘fangs’, and elongate posterior-most dentary teeth that overlap the upper tooth row; (2) a prominent dorsomedian crest extending from the tip of the premaxillary rostrum, and expanding into a low ‘mound-like’ boss between the external bony nasal openings and orbits; (3) a pronounced convex projection on the posterolateral edge of the squamosals; and (4) platycoelous post-axial cervical vertebral centra that are substantially longer than high, and bear both lateral longitudinal ridges and ventral notches. Character state comparisons with the congeneric subfamily specifier Styxosaurus browni suggest that taxonomic distinction is possible, but equivocal. We, therefore, restrict our definition of Styxosaurus to morphologies observable in KUVP 1301. Furthermore, phylogenetic analysis of our first-hand data returns inconsistent elasmosaurid intra-clade relationships, especially with regard to Styxosaurinae. Consequently, we posit that a more targeted reassessment of Elasmosauridae is necessary to resolve both species-level topologies and higher taxonomy within the group.Sven Sachs* [sachs.pal@gmail.com] Naturkunde-Museum Bielefeld, Abteilung Geowissenschaften, Adenauerplatz 2, 33602 Bielefeld, Germany; Johan Lindgren [johan.lindgren@geol.lu.se], Department of Geology, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden; Benjamin P. Kear [benjamin.kear@em.uu.se] Museum of Evolution, Uppsala University, Norbyvägen 16, Uppsala SE-752 36, Sweden. *Also affiliated with: Im Hof 9, 51766 Engelskirchen, Germany. Received 26.5.2016; revised 13.7.2018; accepted 24.7.2018.

The smallest-known neonate individual of Tylosaurus (Mosasauridae, Tylosaurinae) sheds new light on the tylosaurine rostrum and heterochrony

ABSTRACTWe here report on the smallest-known, neonate-sized Tylosaurus specimen, FHSM VP-14845, recovered from the lower Santonian portion of the Niobrara Chalk exposed in Kansas, U.S.A. Lacking any associated adult-sized material, FHSM VP-14845 comprises fragmentary and associated cranial bones, here considered to represent a single neonatal individual with an estimated skull length of 30 cm. Despite its small size, a suite of cranial characters diagnoses FHSM VP-14845 as a species of Tylosaurus, including the elongate basisphenoid morphology. At the same time, FHSM VP-14845 unexpectedly lacks a conical predental rostrum on the premaxilla, generally regarded as diagnostic of this genus. Further, the first and the second premaxillary teeth are closely spaced, with the second set positioned posterolateral to the first, contributing to the overall shortness of the dentigerous premaxilla. Because a conical predental rostrum is already present in ontogenetically young specimens of T. nepaeolicus and T. proriger with respective skull lengths of approximately 40 and 60 cm, formation of such a rostrum must have taken place very early in postnatal ontogeny. Our recognition of a neonate-sized Tylosaurus specimen without an elongate predental rostrum of the premaxilla suggests hypermorphosis as a likely heterochronic process behind the evolution of this iconic tylosaurine feature.

Osteology of the first skull of Aetosauroides scagliai Casamiquela 1960 (Archosauria: Aetosauria) from the Upper Triassic of southern Brazil (Hyperodapedon Assemblage Zone) and its phylogenetic importance.

Aetosauria, which includes 30 species, is a diverse group of armored pseudosuchian archosaurs restricted to Upper Triassic beds. Three species occur in Brazil, and one of these, Aetosauroides scagliai Casamiquela, 1960, also occurs in Argentina. The specimen UFSM 11505, found at Faixa Nova–Cerrito I Outcrop, Santa Maria Formation (Hyperodapedon Assemblage Zone), Santa Maria, Rio Grande do Sul State, Brazil, is here referred to as Aetosauroides scagliai. This specimen preserves most of the skull with both hemimandibles in association with most of the postcranium, thus representing one of the most complete aetosaur skeletons found in Brazil. The premaxilla, one of the key elements of the cranial morphology of aetosaurs, along with the posterior portion of the mandible, was not described until now for A. scagliai. In contrast to the typothoracinae aetosaurs, the premaxilla of UFSM 11505 presents a shovel-shaped tip, but it is not as prominent as the lateral expansion of desmatosuchian aetosaurs, including both species of Stagonolepis, S. robertsoni Agassiz, 1844 and S. olenkae Sulej, 2010. The retroarticular process of the mandible is elongate and not tall, as in Stenomity huangae Small & Martz, 2013 and other typothoracinae aetosaurs. Unlike previous descriptions of A. scagliai, the maxillary teeth are recurved ziphodont-like with serrations on the entire length of both margins. Premaxillary teeth are also present, being less recurved than the maxillary teeth and cylindrical. We recovered Aetosauroides scagliai as the most basal taxon within Aetosauria, like previous phylogenetic analyses. Furthermore, our analyses reinforce that recurved and unconstricted maxillary teeth, the shovel-shaped premaxilla and the presence of a tuber on the surangular are plesiomorphic features of Aetosauria.

A new species of Eigenmannia Jordan Evermann (Teleostei: Gymnotiformes: Sternopygidae) from Río Ventuari, Venezuela.

A new species of Eigenmannia is described from the Río Ventuari, Río Orinoco basin, Venezuela. It is distinguished from congeners by the presence of a bony dorsolateral flange on the dentary, the presence of teeth attached along a bony dorsolateral flange, and by the first premaxillary teeth attached to the anteroventral margin of the premaxilla. It is further distinguished from all remain congeners by a combination of characters, including a subterminal mouth, 99-107 scales along the lateral line until the end of the anal fin, and ii, 16-17 pectoral-fin rays.

A new pachyrhizodontid fish (Actinopterygii, Teleostei) from the Muhi Quarry (Albian-Cenomanian), Hidalgo, Mexico

Abstract. A new genus and species – Motlayoichthys sergioi (ZooBank registration: urn:lsid:zoobank.org:pub:2C503741-2362-4234-8CE0-BB7D8BE5A236, urn:lsid:zoobank.org:act:EF5040FD-F306-4C0F-B9DA-2CC696CA349D) – from the Cretaceous (Albian-Cenomanian) of the Muhi Quarry, Hidalgo, central Mexico is assigned to the family Pachyrhizodontidae based on the presence of the inner premaxillary tooth and a few other cranial characters. Its unique suite of characters, that includes several autapomorphies supports its assignment as a new genus and species, such as the presence of a triangular head with three sides of similar lengths and with its deepest part at the level of the supraoccipital region; the lower jaw projecting anterior to the premaxilla; the ornamentation of cranial bones – especially those of the cheek region – consisting of fine longitudinal crests densely covering the bony surfaces; one or a few deep grooves on the mandibular teeth, which in addition bear acrodin tips ornamented with fine parallel striae; and the position of the dorsal fin, near the posterior margin of the cranium. Motlayoichthys n. gen., together with Michin, Pachyrhizodus, Rhacolepis, and Notelops, is part of the early radiation of pachyrhizodontoids during Albian times.

Two new species of Odontostilbe historically hidden under O. microcephala (Characiformes: Cheirodontinae)

ABSTRACT Specimens historically identified as Odontostilbe microcephala from the upper rio Paraná and Andean piedmont tributaries of the río Paraguay are reviewed and split in three species. We found that the distribution of O. microcephala is restricted to the Andean slope of the río Paraguay basin. The species is distinguished from congeners with subterminal mouth by the elongate body, usually 10-12 gill rakers on upper branch and smaller horizontal orbital diameter (24.6-32.8 % HL, mean 28.7%). Specimens from upper rio Paraná constitute two new species, diagnosed from other Cheirodontinae by the presence of mesopterygoid teeth, grouped on median portion and forming a continuous row. The new species are distinguished from each other by having premaxillary teeth with five cusps vs. nine cusps and by the number of lamellae in left and right sides of central median raphe of olfactory rosette with 20-21 vs. 11-12.

A New Miniature Species ofSerrapinnus(Characiformes: Characidae) from the Upper Rio Araguaia, Brazil

During an expedition to the headwaters of the Rio das Mortes, Mato Grosso, in the Brazilian Shield, a new species of Serrapinnus was found. The new species is distinguished from all congeners by having eight branched dorsal-fin rays, three premaxillary teeth, and a conspicuous dark stripe extending from the eye to the caudal-fin median rays. Among congeners, a similar coloration pattern is present only in S. sterbai, but in that species the stripe usually originates posterior to the eye, on the opercle, and extends to the caudal-fin median rays. In the single locality where the new species was captured, it occurs syntopically with Hyphessobrycon cf. vilmae, another small characid in which a dark midlateral stripe is quite remarkable. Both species were captured together and were observed in situ swimming in mixed shoals. Thus, it is suggested that both species increase their individual chances of survival through the strategy of “protective association” via numeric mimicry.

A functional evaluation of feeding in the surgeonfish Ctenochaetus striatus: the role of soft tissues.

Ctenochaetus striatus is one of the most abundant surgeonfishes on Indo-Pacific coral reefs, yet the functional role and feeding ecology of this species remain unclear. This species is reported to possess a rigid structure in its palate that is used for scraping, but some authors have reported that this element is comprised of soft tissue. To resolve the nature and role of this structure in the feeding ecology of C. striatus we examined evidence from anatomical observations, scanning electron microscopy, histology, X-ray micro-computed tomography scanning, high-speed video and field observations. We found that C. striatus from the Great Barrier Reef possess a retention plate (RP) on their palates immediately posterior to the premaxillary teeth which is soft, covered in a thin veneer of keratin with a papillate surface. This RP appears to be used during feeding, but does not appear to be responsible for the removal of material, which is achieved primarily by a fast closure of the lower jaw. We infer that the RP acts primarily as a ‘dustpan’, in a ‘dustpan and brush’ feeding mechanism, to facilitate the collection of particulate material from algal turfs.

Do multiple karyomorphs and population genetics of freshwater darter characines (Apareiodon affinis) indicate chromosomal speciation?

The role of chromosomal rearrangements in the evolution of species is controversial, and the term chromosomal speciation results from the observation that heterokaryotypes are often infertile. Parodontidae species (a Neotropical fish family) are distinguished only by a few subtle diagnostic morphological characteristics, leading to uncertainty over the inter-relationships and monophyly of the genera. Apareiodon affinis was originally described in the scientific literature as a species isolated from the la Plata river (Buenos Aires, Argentina) and subsequently found in all tributaries of the Rio Paraná basin. In this study, we compared the karyotypic organization, the number of cusps in premaxillary teeth and, nucleotide divergence using DNA barcode for six different demes identified morphologically as A. affinis from different hydrographic subsystems in the Paraná basin (upper Paraná − three demes, Paraguay, Cuiabá, and Uruguay rivers). Cytogenetic data revealed chromosomal differences among the A. affinis demes studied. Chromosomal rearrangements (e.g., translocations, pericentric inversion, and/or, centromere repositioning), differentiation of the ZZ/ZW1W2 multiple sex chromosome system, and accumulation of DNA repeats were proposed to explain the cytogenetic divergence among A. affinis demes. In addition, despite the absence of morphological variation, the molecular analysis demonstrates gene flow restriction among Paraguay, Cuiabá, and Uruguay A. affinis demes and, genetic isolation between upper Rio Paraná basin population from those of the lower Rio Paraná basin demes. Our results demonstrated that different A. affinis karyomorphs have differentiated in subsystems in the Paraná basin and, parapatric populations accumulate chromosomal divergences, supporting the hypothesis of an emerging younger species and/or chromosomal speciation in progress.

Mandaphon nadra, gen. et sp. nov., a new procolophonid from the Manda Beds of Tanzania

ABSTRACTA collaborative field work program in the Triassic of Tanzania and Zambia has produced a plethora of new fossil material. Parareptiles, however, are rare, with only one procolophonoid specimen found to date. In 2012, a new procolophonid parareptile, Mandaphon nadra, gen. et sp. nov., was discovered. The single specimen, consisting of a skull and partial postcranium, displays the autapomorphy of two raised, lozenge-shaped bosses on the quadratojugal. Whereas the posterior maxillary teeth are small, labiolingually expanded, and vaguely bicuspid, the premaxillary teeth are much larger and conical, a trait more commonly found in leptopleuronine procolophonids. The large, lozenge-shaped bosses on the quadratojugal do not correspond to additional ossification in other areas in the skull. In a phylogenetic analysis of procolophonoid relationships consisting of 59 characters and 28 procolophonoid taxa, Mandaphon appears within a poorly supported but monophyletic Leptopleuroninae, the first of this clade found in Africa. The presence of Mandaphon along with the procolophonoid Ruhuhuaria in the Manda Beds is only the third known co-occurrence of members of these two groups, with most non-procolophonid procolophonoids restricted to the Permian and Early Triassic.http://zoobank.org/urn:lsid:zoobank.org:pub:002EE9DA-1D38-41C5-9B0F-2A4BA7A90686SUPPLEMENTAL DATA–Supplemental materials are available for this article for free at www.tandfonline.com/UJVP.Citation for this article: Tsuji, L. A. 2018. Mandaphon nadra, gen. et sp. nov., a new procolophonid from the Manda Beds of Tanzania; pp. 80–87 in C. A. Sidor and S. J. Nesbitt (eds.), Vertebrate and Climatic Evolution in the Triassic Rift Basins of Tanzania and Zambia. Society of Vertebrate Paleontology Memoir 17. Journal of Vertebrate Paleontology 37(6, Supplement).

New species ofHyphessobryconfrom the Rio Teles Pires, Rio Tapajós basin, Brazil (Ostariophysi, Characiformes)

A new species of Hyphessobrycon from the upper Rio Tapajós basin, in the Tapajós-Juruena ecoregion, is described. Hyphessobrycon pinnistriatus n. sp. is distinguished from its congeners by having a black, oblique stripe extending from the origin of the second branched ray to the distal end of the third branched anal-fin ray, lacking a conspicuous black midlateral stripe on the body, inner premaxillary teeth with up to seven cusps, and fins normally hyaline or with scattered chromatophores. The description of a new species that is restricted to the Tapajós-Juruena ecoregion is consistent with this region being an area of high endemism of freshwater fishes.

Skull and postcranium of the bystrowianid Bystrowiella schumanni from the Middle Triassic of Germany, and the position of chroniosuchians within Tetrapoda

Chroniosuchians form a mainly terrestrial or semi-terrestrial clade of Permian and Triassic crocodile- or varanid-like tetrapods, usually considered stem amniotes, but with disputed affinities within that grade. Two groups can be distinguished, the chroniosuchids and bystrowianids. Whereas the chroniosuchid skull and postcranium are well known, our knowledge of bystrowianids is restricted mainly to isolated vertebrae and osteoderms. The Middle Triassic bystrowianid Bystrowiella schumanni from south-western Germany was identified as the first taxon of this clade outside Russia and China, based on the morphology of its vertebrae and osteoderms. Here we expand on a full description of cranial and postcranial remains from this taxon, based on a partially articulated specimen and further isolated material. The material comprises large parts of the dermal skull roof, the pectoral girdle, ribs and limbs, and sheds light on many anatomical regions formerly unknown in bystrowianids. Among the autapomorphic features of Bystrowiella are the premaxilla with an edentulous crest lateral to the choana, the premaxillary teeth with conspicuous size differences, the jugal with an extremely long, narrow anterior process, and the enlarged postparietals and tabulars forming facets for articulation with the anteriormost osteoderm. As in chroniosuchids, the pre- and postfrontal are not in contact, but unlike in chroniosuchids, the internarial fontanelle and the antorbital fenestra are absent. In the amniote-like postcranium, the interclavicle is slender and has a conspicuous parasternal process, the humerus is waisted and bears a short supinator process, and the long, curved trunk ribs have widely separated rib heads and a slender shaft without blades or processes. Phylogenetic analysis, particularly based on numerous new postcranial features, supports the monophyly of chroniosuchians, even when the constituent synapomorphies (osteoderm and vertebral characters) are excluded from the matrix. Chroniosuchians nest at the base of the amniote stem, forming an unresolved polytomy with Silvanerpeton, embolomeres and more advanced stem amniotes.

A new species of Tometes Valenciennes 1850 (Characiformes: Serrasalmidae) from Tocantins-Araguaia River Basin based on integrative analysis of molecular and morphological data.

A new large serrasalmid species of Tometes is described from the Tocantins-Araguaia River Basin. Tometes siderocarajensis sp. nov. is currently found in the rapids of the Itacaiúnas River Basin, and formerly inhabited the lower Tocantins River. The new species can be distinguished from all congeners, except from T. ancylorhynchus, by the presence of lateral space between 1st and 2nd premaxillary teeth, and by the absence of lateral cusps in these two teeth. However, T. siderocarajensis sp. nov. can be differentiated from syntopic congener T. ancylorhynchus by an entirely black with mottled red body in live specimens, densely pigmented pelvic fins with a high concentration of dark chromatophores, and the presence of 39 to 41 rows of circumpeduncular scales (vs. silvery body coloration with slightly reddish overtones on middle flank during breeding period in live specimens, hyaline to slightly pale coloration on distalmost region of pelvic fins, and 30 to 36 rows of circumpeduncular scales). Additionally, molecular sequence shows that T. siderocarajensis sp. nov. is reciprocally monophyletic, and diagnosable from all congeners by having two autapomorphic molecular characters in the mitochondrial gene COI. The phylogenetic reconstruction still show that T. siderocarajensis sp. nov. is closely related to T. trilobatus. This is the first molecular study using an integrative taxonomic approach based on morphological and molecular sequence data for all described species of Tometes. These findings increase the number of formally described species of Tometes to seven. A key to the Tometes species is provided.

Phycocharax rasbora, a new genus and species of Brazilian tetra (Characiformes: Characidae) from Serra do Cachimbo, rio Tapajós basin.

A new genus and species of characid fish is described from rio Braço Norte, a tributary of rio Teles Pires, Tapajós basin, Mato Groso, Brazil. The new taxa can be diagnosed from the remaining characids by a unique combination of characters that includes the presence of a single row of relatively compressed premaxillary teeth, large teeth with four to nine cusps on premaxillary and dentary, absence of pseudotympanum, incomplete lateral line with 7–13 pored scales, sexually-dimorphic males with distal margin of anal fin approximately straight, and presence of a nearly triangular and horizontally elongated blotch from the posterior half of the body to caudal peduncle. The most parsimonious phylogenetic hypothesis, using morphological data, recovered the new genus and species in a clade including Paracheirodon axelrodi and Hyphessobrycon elachys.

A new species of Eigenmannia Jordan and Evermann (Gymnotiformes:Sternopygidae) from the upper rio Paraguai basin.

Eigenmannia correntes, a new species belonging to the Eigenmannia trilineata species-group, is described from tributaries of rio Correntes, a major affluent of the rio Piquiri system, upper rio Paraguai basin (Mato Grosso and Mato Grosso do Sul states, Brazil). Eigenmannia correntes is included in the currently poorly defined sternopygid genus Eigenmannia (Ostariophysi: Gymnotiformes) by presenting characters that are either primitive or of uncertain polarity, such as eyes covered by skin, scales present over entire postcranial portion of body, teeth absent from oral valve, infraorbital bones 1+2 with enlarged posterodorsal expansion, and gill rakers short and unossified. The new species is distinguished from all congeners, except those species included in the Eigenmannia trilineata species-group, by the presence of a conspicuous superior midlateral stripe (synapomorphy of this clade). Eigenmannia correntes can be differentiated from all members of the Eigenmannia trilineata species-group, except E. vicentespelaea, E. waiwai and E. besouro, by its subterminal mouth (vs. terminal in remaining species of that group). Further, it differs from these aforementioned species by a number of meristic and morphometric characters, including number of premaxillary and dentary teeth, number of longitudinal series of scales above lateral line, number of pectoral-fin and anal-fin rays, eye diameter, postorbital distance, and snout length. Finally, notes on reproduction and parasitism for E. correntes are presented.