Mosasaurus beaugei Arambourg, 1952 (Squamata, Mosasauridae) from the Late Cretaceous phosphates of Morocco

Mosasaurus beaugei Arambourg, 1952 was based on isolated teeth from the Maastrichtian phosphatic deposits of Morocco. The recent discovery of new material, including skull and mandibular remains, improves our knowledge of this species. M. beaugei shares the following synapomorphies with the genus Mosasaurus: large teeth bearing two prominent carinae and with asymmetrical labial and lingual surfaces, the labial one being flattened and strongly facetted and the lingual one being convex; premaxillae with a small pointed rostrum and dentary without rostrum; palatal elements closely united; coronoid with very large ventromedial process overlying the prearticular. M. beaugei is characterised by the following autapomorphies: 12-13 maxillary teeth; marginal teeth bearing 3-5 prisms on the labial surface and 8-9 on the lingual one; palatine with posterior border concave and perpendicular to the long axis of the skull; splenial visible laterally on half of the dentary ventral surface; coronoid with anterior wing well developed and bearing two notches. M. beaugei is only known to date in the Maastrichtian phosphates of Morocco.     

Osteological analysis of the killifish genus Cynolebias (Cyprinodontiformes: Rivulidae)

Relationships among the species of the annual fish Cynolebias are unclear. An analysis of the variation and utility of osteological characters for phylogenetic analysis was done using cleared and double-stained specimens representing 21 species of Cynolebias. This analysis showed that some of the characters previously used to diagnose this genus and some of the species are polymorphic. Osteologically, Cynolebias can be diagnosed by the following synapomorphies: (1) triangular-shaped parietal, (2) vomer positioned ventral to the parasphenoid, (3) long ventral process of the dentary, (4) teeth on fourth ceratobranchial, and (5) teeth on first epibranchial. In addition, characters that help define some of the currently recognized species complexes were identified. Species in the “antenori complex” share at least five synapomorphies, such as ossified medial radials of dorsal and anal fins, four pectoral radials, ventral process of the maxillae enlarged, mesopterygoid long relative to the autopalatine, and proportion of cartilage in the basihyal. The “bellottii complex” is characterized by having a reduced basihyal and a deep urohyal, whereas species in the “elongatus complex” possess a caudal fin supported by four vertebrae and have unique modifications of jaw bones. The following osteological features are useful as diagnostic characters at the specific level: (1) Two vertebrae supporting the caudal fin (C. nigripinnis); (2) cartilaginous pelvic bones (C. notatus); (3) short third postcleithrum and broad lateral process of the sphenotic (C. wolterstorffi); (4) thick third postcleithrum (C. gymnoventris); (5) crest on the parietal and reduced in the upper portion of the lacrimal (C. whitei); (6) anteriorly curved lacrimal (C. cheradophilus); (7) second dermosphenotic (C. bellottii); and (8) expansion of the ventral tip of the maxillae and long basyhial (C. constanciae). J. Morphol. 238:245–262, 1998. © 1998 Wiley-Liss, Inc.     

Two new species of Leporinus (Characiformes: Anostomidae) from the Brazilian Amazon,and redescription of Leporinus striatus Kner 1858

Two new species of Leporinus are described from tributaries of the Rio Amazonas in Brazil. One species is known from the Jari and Tapajós River basins, and is identified on the basis of a gas bladder reduced in size, a dark midlateral stripe on the body, dark transverse bars on the dorsum, a subinferior mouth, three teeth on the premaxilla, four teeth on the dentary and 16 scale rows around the caudal peduncle. The second new species is known from the Tocantins, Xingu and Tapajós River basins, and is identified on the basis of three dark longitudinal stripes on the body, a subinferior mouth, three teeth on the premaxilla, four teeth on the dentary and 12 scale rows around the caudal peduncle. In addition, Leporinus striatus is redescribed based on type and additional specimens from the Río de La Plata, Amazonas, Orinoco, Atrato, Magdalena and Sinu River basins. Leporinus striatus is identified on the basis of four dark longitudinal stripes on the body, a subterminal mouth, three teeth on the premaxilla, four teeth on the dentary and 16 scale rows around the caudal peduncle.     

Parotocinclus jacksoni,a new hypoptopomatine catfish (Siluriformes: Loricariidae) from the Rio Mamanguape basin,north-eastern Brazil

A new species of Parotocinclus is described from the Rio Mamanguape basin, in the State of Paraíba, north-eastern Brazil. The new species can be distinguished from all of its congeners, except for P. bahiensis, P. cesarpintoi, P. jumbo, P. nandae and P. spilosoma, by the presence of an abdomen covered by a few small and dispersed platelets (vs. an abdomen entirely covered by large plates in adult individuals or the absence of plates in that region). The new species differs from those mentioned above with respect to several features, such as an exposed pectoral girdle and supporting odontodes medially and laterally, the number of premaxillary and dentary teeth, odontodes covering only the lateral portion of the cleithrum and the absence of irregular golden lines on the head and body (colour in vivo). The new species was collected only in the upper and middle portions of the Rio Mamanguape basin, suggesting a geographic distribution restricted to the Caatinga biome.     

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 new species of Chrysobrycon (Characiformes,Characidae, Stevardiinae) from the Amazon River basin in Colombia,with a new diagnostic characteristic for the genus

Chrysobrycon mojicai sp. nov. is described from forest streams that are part of the Amazon River basin in Colombia. It is distinguished from all congeners by having most of the maxillary teeth with distal tips lateroventrally curved (v. teeth straight along their lengths) and a greater number of dentary teeth (20–27 v. 11–19, except in Chrysobrycon yoliae). The posterior margin of the ventral process of the quadrate does not reach the vertical through the posterior margin of the symplectic and these features differentiate C. mojicai from Chrysobrycon myersi and C. yoliae (v. posterior margin of ventral process of quadrate reaching vertical through posterior margin of symplectic). In species of Chrysobrycon, the frontals are extensively contacting each other along the midline, resulting in an absent frontal fontanel and a reduced parietal fontanel. This extensive contact between the frontals modifying the fontanels is a condition rarely found within the Stevardiinae and hence is proposed as an additional diagnostic characteristic for the genus. An updated identification key for all Chrysobrycon species is provided.     

Hemiodus bimaculatus,a new species of Hemiodontidae from the Rio Tapajós drainage,Brazil (Ostariophysi: Characiformes)

Hemiodus bimaculatus sp. nov., is described from tributaries of the Rio Juruena and Rio Teles Pires in the upper Rio Tapajós basin. The new species is diagnosed from most congeners, except Hemiodus jatuarana, by having a conspicuous circular or horizontally elongate dark blotch on the caudal peduncle (v. inconspicuous in H. iratapuru and absent in the other species). The new species differs from H. jatuarana by having a round midlateral spot on the flank (v. absent in H. jatuarana), 98–121 perforated scales in the lateral line (v. 66–72 in H. jatuarana), 23–28 scale series above and 14–19 below lateral line (v. 12–13 above and 6–7 below in H. jatuarana). Hemiodus bimaculatus is hypothesised to be related to species of the H. microlepis group, from which it also differs by having 11–25 epibranchial (v. 26–34 in H. argenteus, 29–39 in H. microlepis, 21–42 in H. orthonops and 27–35 in H. parnaguae) and 18–31 ceratobranchial (v. 38–50 in H. argenteus, 43–58 in H. microlepis, 32–52 in H. orthonops and 34–48 in H. parnaguae) gill rakers in the first arch.     

A new species of Astyanax (Characiformes: Characidae) from Costa Rica and Panama,with a key to the lower Central American species of the genus

Astyanax anai, a new species of characid fish, is described from the Sixaola River basin, eastern Costa Rica–western Panama, Central America. The new species can be distinguished from all other congeners by the following combination of characters: premaxillary teeth 4–5 at the inner series and 4–6 at the outer series; maxillary teeth tricuspid, 2–4; predorsal scale series irregular and incomplete, with an unscaled space behind tip of supraoccipital process and 12–14 scales; lateral line scales 34–39; humeral region with a conspicuous black and rounded to horizontally ovate spot and two diffuse brown and vertically elongate bars (the first through the rounded to horizontally ovate spot, the second 2–4 scales behind the first); body depth 36·6–42·3% of standard length (L_S); midlateral stripe formed by a series of 10–14 anteriorly‐directed dermal herringbone, or chevron‐shaped, marks, most apparent in juveniles and in preserved specimens, extending above the lateral line from the black humeral spot or just behind it (from the second vertical bar) to the caudal peduncle; scale rows from lateral line to base of first dorsal‐fin ray 8–9; scale rows from lateral line to base of pelvic fin 7–8; pre‐anal distance 53·9–61·9% of L_S; total anal‐fin elements 29–33; caudal spot elongated, rhomboid or rectangular, with its anterior margin surpassing the middle of the caudal peduncle, usually reaching the anal‐fin insertion, posteriorly covering 4–7 principal caudal‐fin rays and not extending onto the ventral and dorsal margins of the caudal peduncle, covering 3–5 horizontal scale rows. In order to test the phylogenetic relationships of the new taxon in relation to the other North and Central American species of the genus, a new phylogenetic hypothesis based on a reanalysis of the morphological matrix by Schmitter‐Soto (2016) is proposed. A key to the lower Central American (southern Nicaragua to eastern Panama) species of Astyanax is also provided.     

Shape variation in the mole dentary (Talpidae: Mammalia)

The clade Talpidae consists of specialized fossorial forms, shrew‐like moles and semi‐aquatic desmans. As with all higher jawed vertebrates, different functional, phylogenetic and developmental constraints act on different parts of dentary influencing its shape. In order to determine whether morphological variation in the dentary was unified or dispersed into an integrated complex of structural–functional components, a morphometric analysis of the mole dentary was undertaken. The dentary was subdivided into component parts – horizonal ramus; coronoid, condylar, angular processes of the ascending ramus – and outline‐based geometric morphometric methods used to quantify, compare and contrast modes of shape variation within the clade. These were successful in revealing subtle differences and aspects of shape important in distinguishing between mole genera. Closer examination of shape variation within the two fully fossorial mole clades (Talpini and Scalopini) revealed several similarities in ascending ramus shapes between genera from each clade. For example, the broad, truncated appearance of the coronoid process in the talpine genera Talpa and Parascalops was shared with the scalopine genus Scapanus. Also, the more slender, hook‐shaped coronoid process of Euroscaptor and Parascaptor (Talpini) closely resembles that of Scalopus (Scalopini). Interestingly, subspecies (one from each clade) more closely resembled genera other than their own in coronoid process shape. Important distinctions in horizontal ramus shape were found to exist between the two clades, such as the extent of curvature of the ventral margin and relative depth of the horizontal ramus. Results show shape variation in this region is correlated with dental formulae and the relative sizes of the teeth. The taxonomically important dentition differences characteristic of mammals are also reflected in the horizontal ramus results. Moreover, these results suggest size may be affecting shape and the extent of variation in, for example, the coronoid and condylar processes between the semi‐aquatic moles Desmana and Galemys. It is likely that the effects of morphological integration seen at this level of analysis – covariation between shapes of dentary components – may exist because interacting traits are evolving together. Horizontal ramus and coronoid process shape, for example, are similar across Scapanus and Parascalops, but both these shapes have diverged in Scalopus. © 2008 Trustees of the Natural History Museum (London). Journal compilation © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 153 , 187–211.     

Molecular and morphological diversity in species of Kronichthys (Teleostei,Loricariidae) from Atlantic coastal rivers of Brazil

The Neotropical catfish genus Kronichthys contains three species distributed along coastal rivers of southern and southeastern Brazil. Although phylogenetic hypotheses are available, the molecular and morphological diversity and species boundaries within the genus remain unexplored. In this study, the authors generated mitochondrial data for 90 specimens combined with morphometric and meristic data to investigate species diversity, species boundaries and putative morphological signatures in Kronichthys. Phylogenetic and species delimitation results clearly show the presence of four genetic lineages, three within Kronichthys heylandi along the coast from Rio de Janeiro to southern São Paulo and a single lineage encompassing both the nominal species Kronichthys lacerta and Kronichthys subteres from the Ribeira de Iguape basin to Santa Catarina in southern Brazil. Nonetheless, morphological data show overlapped ranges in morphometrics and a definition of only two morphotypes, with clear phenotypic differences in the teeth number: K. heylandi differs from K. subteres + K. lacerta by the higher number of premaxillary teeth (30–52 vs. 19–28) and higher number of dentary teeth (28–54 vs. 17–28). Headwater captures and connections of paleodrainages because of sea-level fluctuations represent the two major biogeographic processes promoting species diversification and lineage dispersal of Kronichthys in the Atlantic coastal range of Brazil.     

The rostral micro-tooth morphology of blue marlin,Makaira nigricans

Billfish rostra potentially have several functions; however, their role in feeding is unequivocal in some species. Recent work linked morphological variation in rostral micro-teeth to differences in feeding behavior in two billfish species, the striped marlin (Kajikia audax) and the sailfish (Istiophorus platypterus). Here, we present the rostral micro-tooth morphology for a third billfish species, the blue marlin (Makaira nigricans), for which the use of the rostrum in feeding behavior is still undocumented from systematic observations in the wild. We measured the micro-teeth on rostrum tips of blue marlin, striped marlin, and sailfish using a micro–computed tomography approach and compared the tooth morphology among the three species. This was done after an analysis of video-recorded hunting behavior of striped marlin and sailfish revealed that both species strike prey predominantly with the first third of the rostrum, which provided the justification to focus our analysis on the rostrum tips. In blue marlin, intact micro-teeth were longer compared to striped marlin but not to sailfish. Blue marlin had a higher fraction of broken teeth than both striped marlin and sailfish, and broken teeth were distributed more evenly on the rostrum. Micro-tooth regrowth was equally low in both marlin species but higher in sailfish. Based on the differences and similarities in the micro-tooth morphology between the billfish species, we discuss potential feeding-related rostrum use in blue marlin. We put forward the hypothesis that blue marlin might use their rostra in high-speed dashes as observed in striped marlin, rather than in the high-precision rostral strikes described for sailfish, possibly focusing on larger prey organisms.     

The cranial anatomy and taxonomy of Peloneustes philarchus (Sauropterygia,Pliosauridae) from the Peterborough Member (Callovian,Middle Jurassic) of the United Kingdom

Abstract: Peloneustes philarchus is the most abundant pliosaurid from the Peterborough Member of the Oxford Clay Formation (Callovian) of the UK. It is a valid taxon possessing a unique character combination, including a single autapomorphy: the interdentary symphysis is raised dorsally on a narrow platform. Twenty‐one specimens can be positively referred to P. philarchus. However, other specimens previously referred to Peloneustes, from the Peterborough Member near Peterborough, and the lower Oxfordian strata of Marquise, northern France, represent distinct, unnamed taxa. The skull of P. philarchus is described in detail, including new information from an uncrushed, three‐dimensionally preserved specimen and a specimen with a well‐preserved palate. Well‐preserved material clearly indicates that P. philarchus lacked nasals, but possessed a lacrimal. A previously unrecognised ‘palpebral’ forms part of the dorsal orbit margin adjacent to the prefrontal. The number of maxillary (30–31) and dentary (36–44) alveoli, the number of dentary alveoli adjacent to the mandibular symphysis (13–15), the number of foramina on the frontal and jugal, the breadth of the parasphenoid, breadth of the anterior (narial) process of the palatine and the presence of a lappet of the angular that extends onto the posterodorsal surface of the retroarticular process vary among individuals but are not considered sufficient to justify the recognition of new taxa. The presence of an open palpebral–prefrontal suture, the size of the ventral midline tubercle of the basioccipital and the presence of an anterior interpterygoid vacuity seem to vary with body size.     

Ichthyosauria from the Upper Lias of Strawberry Bank,England

Abstract: Eight remarkably preserved specimens of ichthyosaurs from the lower Toarcian (Lower Jurassic) of Strawberry Bank (Ilminster, Somerset, England) are described fully for the first time. Whereas previously these ichthyosaurs were assigned to one species, Stenopterygius hauffianus, our study shows there are two, Stenopterygius triscissus and Hauffiopteryx typicus. S. triscissus is a small‐ to medium‐sized ichthyosaur up to 3.5 m long, characterised by three apomorphies: long and slender rostrum, large elliptical supratemporal fenestra and bipartite pelvis. H. typicus is a small ichthyosaur up to 2.95 m long, with five apomorphies: short and extremely slender rostrum, very large orbit, small rounded supratemporal fenestra and tripartite pelvis, which is fused distally. Cladistic analysis is equivocal about their relationships, suggesting either that Hauffiopteryx and perhaps also Stenopterygius are members of a clade Eurhinosauria or that this clade does not exist, and both genera are members of a wider clade Thunnosauria. Further, the clade Stenopterygiidae, in which Hauffiopteryx had been located, is not identified. Most striking is that the specimens are all juveniles (five specimens) or infants (three specimens), ranging from one‐tenth to one‐half the normal adult length of the species.     

Hypostomus sertanejo (Siluriformes: Loricariidae), new armoured catfish species from north‐eastern Brazil

A re‐evaluation of the armoured catfish species of Hypostomus in the Rio Jaguaribe, north‐eastern Brazil, was prompted by the discovery of specimens with pale spots on a dark background collected from that basin c. 1936 and deposited at the Academy of Natural Sciences of Philadelphia. Recent field collections in the Rio Jarguaribe basin confirmed the presence of the pale‐spotted specimens and its distinctiveness as a new species. Hypostomus sertanejo n. sp. is diagnosed from other species of Hypostomus by having fins and dermal‐plated regions of head and body with pale spots or vermiculations on darker background, teeth slender, asymmetrically bicuspid and numerous (34–75) on dentary and premaxilla, depressed dorsal‐fin spine not reaching adipose spine, unbranched pectoral‐fin spine longer than unbranched pelvic‐fin ray, seven branched dorsal‐fin rays and one (rarely two) predorsal plate(s) bordering supraoccipital. Ancistrus salgadae Fowler 1941 is hypothesized to be a junior synonym of Hypostomus carvalhoi (Miranda‐Ribeiro, 1937), a dark‐spotted Hypostomus described from the Rio Granjeiro, a tributary to the upper Rio Salgado.     

Jenynsia lineata species complex,revision and new species description (Cyprinodontiformes: Anablepidae)

The Jenynsia lineata species complex comprises J. lineata from Montevideo, Uruguay and Jenynsia multidentata, from coastal basins of Brazil, Uruguay and Argentina up to 1200 m a.s.l. Taxonomic divisions within this group were tested using three different species delimitation methods, which found the two existing names to be synonyms and revealed a new cryptic species. Jenynsia darwini sp. nov. is distinguished from all congeners by having a unique combination of character states, including the shape of the dorsal postcleithrum (three times higher than wide v. less than two times higher than wide) and female colour pattern in the half of the caudal peduncle with rows of chromatophores segmented in unaligned spots (v. aligned spots forming lines). The new species also differs from J. lineata by having 26 nucleotide substitutions in the mitochondrial gene cytochrome c oxidase I (coI). Phylogenetic analysis of the genus based on morphological characters proposed by previous studies corroborates monophyly of the subgenera Plesiojenynsia and Jenynsia, with the new species being allocated to the subgenus Jenynsia as the sister group of J. lineata.     

A new species of Acynodon (Crocodylia) from the upper cretaceous (Santonian–Campanian) of Villaggio del Pescatore,Italy

Abstract: The new species Acynodon  adriaticus is described on the basis of remains from the Santonian–Campanian of Villaggio del Pescatore (Trieste, NE Italy). This species differs in several cranial features from Acynodon  iberoccitanus, the only other Acynodon species whose cranial osteology is known in detail. The absence of maxillary and dentary caniniform teeth coupled with the presence of enlarged molariform teeth suggests that Acynodon probably fed on slowly moving hard‐shelled prey. Moreover, the new materials reveal for the first time the morphology of some postcranial elements of Acynodon: in particular, medial‐most paravertebral osteoderms that are characterized by two keels. A new cladistic phylogenetic analysis resolves the previously reported polytomy among the basal Globidonta: Acynodon is recognized as the most primitive globidontan. This genus may represent the geologically oldest known globidontan. The fact that Acynodon has been found only in Europe and that the outgroup of Globidonta, the Diplocynodontinae, is mainly known from Europe, suggests that globidontans may have originated in Europe and not in North America as previously supposed.     

Redescription of Chlorophthalmus corniger,a senior synonym of Chlorophthalmus bicornis (Family: Chlorophthalmidae)

Chlorophthalmus corniger is redescribed on the basis of recently collected specimens. The species is redefined as a species of Chlorophthalmus with the lower jaw terminating in a distinctly projecting horizontal plate with strong, spine‐like processes directed forward from the plate's corners; body silvery grey, with numerous minute black spots and traces of broad darker crossbars; base of anterior dorsal fin spines and distal parts of dorsal fins black; adipose fin tiny with numerous black spots; caudal fin black; 3·5 scales above lateral line; three rows of cheek scales; head very large, 34·3–40·1% standard length (L_S); eye large, 29·8–40·8% head length (L_H); pectoral fin long, extending to beyond dorsal fin base, 21·7–26·2% L_S. Chlorophthalmus bicornis is a junior synonym of C. corniger based on the examination of the type series of both species. It is confined to the northern half of the Indian Ocean, reliably recorded from Somalia and the Gulf of Aden to southern Java, Indonesia, at depths between 200 and 500 m. A lectotype and three paralectotypes were designated for C. corniger. DNA barcodes for Indian species of Chlorophthalmus were generated.