Hypertrophied Odontodes Research Articles

A new species of spiny Rineloricaria (Siluriformes: Loricariidae) from the Rio Paraba do Sul basin and costal rivers from Rio de Janeiro State.

Although the genus Rineloricaria is widely distributed in the Neotropical region, its species usually occupy single drainages with high habitat fidelity. Rineloricaria species show evident sexual dimorphism with hypertrophied odontodes in sexually mature males. Here, we describe a new species of Rineloricaria present in the Rio Paraiba do Sul basin and coastal rivers in Rio de Janeiro State. The new species has extreme sexual dimorphism making possible to differentiate it from all congeners. The new species can also be separated from other sympatric species by morphometric characteristics and dermal plates pattern.

New species of the Corumbataia cuestae group (Siluriformes: Loricariidae) from the Rio Tocantins basin, with comments on its phylogenetic relationships

Abstract A new species of Corumbataia is described from Rio Maranhão, Rio Tocantins basin, central Brazil. The new species is distinguished from all congeners by the presence of a small, naked area on snout tip; by having the abdomen covered with small platelets forming a shield which reaches the lateral mid-ventral plates; by the anterior profile of the head rounded in dorsal view; by the lower lip not reaching the transversal line of the pectoral girdle; and by the presence of 28 or 29 vertebrae. High genetic divergence in mitochondrial cytochrome c oxidase subunit I (COI) further supports the validity of this new species. Our phylogenetic analysis shows a derived subclade in Corumbataia, herein named as the Corumbataia cuestae group, composed of the new species plus C. cuestae, C. tocantinensis, C. britskii, C. liliai, and C. lucianoi. This group is defined by having a conspicuous crest of hypertrophied odontodes on head; absence of the adipose fin or a single series of platelets at adipose-fin position; and anastomosis of the infraorbital and otic sensory canals over the pterotic-supracleithrum. Here we also restrict the distribution of C. tocantinensis to the Rio Araguaia basin.

An Enigmatic New Loricariid (Actinopterygii: Siluriformes) from Relictual Upper Reaches of Chapada Diamantina, Bahia, Brazil

Parotocinclus adamanteus, new species, is described from a series of specimens collected in the upper portion of the Rio Paraguaçu basin, a coastal river within the Chapada Diamantina domain, a large plateau on the State of Bahia in northeastern Brazil. The description of this new species represents the first record of a member of the Hypoptopomatinae from this relictual area. The new species is diagnosed from other Parotocinclus by having a distinct rostral border forming a fleshy intumescence on the lateral portion of head ornamented with moderately hypertrophied odontodes in adult males. It is also diagnosed from congeners by a remarkable secondary sexual dimorphism in the shape of the pelvic fin, in which the branched rays of males decrease in size, resulting in a pointed posterior fin margin (branched pelvic-fin rays in females have approximately the same size, producing a round posterior fin margin). In addition, the new species can be further distinguished from other species of Parotocinclus by lacking a rostral plate covering the tip of the mesethmoid anteriorly, by lacking abdominal plates between the pectoral girdle and the anus, by having numerous premaxillary teeth (45–61), and by having a short and mesially expanded ventral portion of the cheek canal plate. Recent phylogenetic analysis indicates that Parotocinclus adamanteus, new species, is closely related to P. jequi, P. prata, and P. robustus.

New loricariid fishes from headwaters on Serra da Mantiqueira and Complexo do Espinhaço, Minas Gerais State, Brazil (Teleostei: Siluriformes: Loricariidae).

Three new species, of three different genera of loricariids, are described from the headwaters of Serra da Mantiqueira and Cadeia do Espinhaço, in Southeastern Minas Gerais State, Brazil. In this region, the Serra da Mantiqueira and the Complexo do Espinhaço are the highest points of the Brazilian Shield and delimits the headwaters of four drainages: São Francisco, Paraná, Doce and Paraíba do Sul basins. Harttia intermontana, n. sp., is described from the headwaters of the Rio Doce basin and is the first record of the genus in this basin. The new species can be distinguished from its congeners by the pattern of abdominal covering, presence of preanal plates, presence and pattern of ornamentation of canal plate, and some characteristics related to sexual dimorphism. Pareiorhaphis togoroi, n. sp., is described from the headwaters of the Rio das Mortes basin, tributary to the Rio Grande, in the upper Rio Paraná drainage, and represents the first record of the genus to this drainage, thus expanding its geographic distribution. It can be distinguished from most congeners by the absence of preadipose azygous plates, and characteristics related to secondary sexual characters of mature males: presence of odontodes on the lateral margin of head plus the absence of long hypertrophied odontodes on pectoral-fin spine. Neoplecostomus pirangaensis, n. sp., is described from the headwaters of the Rio Piranga, Rio Doce basin. The new species differs from all congeners by the much-reduced dermal platelets on the abdomen, devoid of developed odontodes between the insertions of the pectoral and pelvic fins. Neoplecostomus pirangaensis can also be distinguished from all congeners, except N. botucatu and N. paranensis, due to the complete absence of vestiges of the adipose fin (vs. vestiges, or adipose fin moderate to well developed and always present). The new species differs from N. botucatu by the absence of conspicuous dark spots all over the body and the presence of common dorsal bands in juveniles, and almost totally black in adults. It differs from N. paranensis by the bigger and less numerous teeth. Additionally, the new species differs from Neoplecostomus doceensis by the absence of enlarged fleshy folds between dentaries, and absence of a lateronasal plate.

Two new species of Pseudancistrus (Siluriformes, Loricariidae) from the Amazon basin, northern Brazil.

Two new species of Pseudancistrus, a genus diagnosed by non-evertible cheek plates and hypertrophied odontodes along the snout margin, are described from two drainages of the Brazilian Shield: Pseudancistrus kayabi from the rio Teles Pires (rio Tapajós basin) and Pseudancistrus asurini from the rio Xingu. The new species are distinguished from congeners (Pseudancistrus barbatus, Pseudancistrus corantijniensis, Pseudancistrus depressus, Pseudancistrus nigrescens, Pseudancistrus reus, and Pseudancistrus zawadzkii) by the coloration pattern. Pseudancistrus kayabi has dark bars on the dorsal and caudal fins which are similar to that of Pseudancistrus reus from the Caroní River, Venezuela. Pseudancistrus asurini is unique among Pseudancistrus in having whitish tips of the dorsal and caudal fins in juveniles to medium-sized adults.

A Remarkable Sexually Dimorphic New Genus and Species of Neoplecostomine Catfish (Siluriformes, Loricariidae) from a Coastal Drainage of Eastern Brazil

A new neoplecostomine genus and species is described from headwater tributaries of the lower Rio Pardo basin, a coastal drainage in Bahia, eastern Brazil. Hirtella carinata is a small loricariid with a maximum standard length barely reaching 50 mm. The new genus and species are diagnosed among all other loricariids by a unique, remarkable pattern of sexual dimorphism in which adult males have five conspicuous longitudinal rows of bristle-like hypertrophied odontodes on the head and along the lateral dermal plates of the body. Hirtella is further distinguished from most loricariids by the anterior position of the pelvic fin, which originates in a vertical anterior to the nuchal plate, and by the possession of an elongate keel formed by 15–17 azygous plates along the mid-dorsal line between the dorsal and the caudal fins. Hirtella is additionally distinguished from other members of the Neoplecostominae by having a medium sized palatine splint, never reaching the anterior border of the nasal fossa. Phylogene...

A new spiny species of Hypostomus Lacépède (Loricariidae: Hypostominae) from thermal waters, upper rio Paraná basin, central Brazil

A new species of Hypostomus is described from the rio Quente, rio Paranaíba drainage, in the upper rio Paraná basin in central Brazil. The rio Quente is a peculiar small and shallow fast water stream with water temperatures around 34ºC. The new species is distinguished from all congeners by having the five lateral series of plates with hypertrophied odontodes not aligned in rows and more conspicuous on flanks of caudal peduncle of the larger specimens. The new species is only known from the rio Quente.

New species of the Pseudancistrus barbatus group (Siluriformes, Loricariidae) with comments on its biogeography and dispersal routes.

A new species of Pseudancistrus is described from the Tapajós Basin, and assigned to the P. barbatus group by having hypertrophied odontodes along the snout and lacking evertible cheek plates. The new species is distinguished from other species in that group (P. barbatus, P. corantijniensis, P. depressus and P. nigrescens) by its pattern of spots, length and color of snout odontodes, greater head depth, cleithral width, anal-fin spine length, peduncle depth and internares width. Molecular phylogenetic results corroborate placement of the new species in the Pseudancistrus barbatus group which is otherwise distributed in the Xingu Basin and rivers draining the Guyana Shield into the Atlantic Ocean. Topology tests strongly reject alternative hypotheses supporting close relationships with Guyanancistrus, Lithoxancistrus or the species Pseudancistrus pectegenitor, P. sidereus and P. genisetiger. Additionally, we propose two hypotheses on the distribution of the new species in the rio Tapajós, a Brazilian Shield drainage. The first one proposes that ancestral stock of the P. barbatus group was widely distributed throughout rivers draining the Guyana and Brazilian shields, and the species P. zawadzkii and Pseudancistrus sp. L17 are in the limit of the distribution for the group in Tapajós and Xingu rivers. The second hypothesis proposes that ancestral stock of the P. barbatus group was restricted to Guyana Shield rivers, and that headwater capture events permitted several dispersal routs through Guyana and Amazon rivers, permitted that the ancestral lineages of Pseudancistrus sp. L17 and P. zawadzkii reached the rivers of Amazon basin.

A new trans-Andean Stick Catfish of the genus Farlowella Eigenmann & Eigenmann, 1889 (Siluriformes: Loricariidae) with the first record of the genus for the río Magdalena Basin in Colombia.

A new species of Farlowella is described from El Carmen de Chucurí in the Departamento de Santander, western flank of the Cordillera Oriental, río Magdalena Basin, Colombia. Farlowella yarigui n. sp. differs from its congeners in lateral body plate morphology, abdominal cover, cephalic hypertrophied odontodes, and details of coloration. This is the first verifiable record of the genus in the Magdalena drainage. Aspects of natural history and implications of this finding are provided concerning the state of knowledge of the fishes of the río Magdalena Basin. Previous records of Farlowella gracilis in the río Cauca basin are examined and herein considered erroneous, rendering the new species the only representative of the genus in the Magdalena-Cauca system. A key to species of Farlowella from Colombia is provided.

Description of Neblinichthys peniculatus, a new species of loricariid catfish from the río Paragua drainage of Venezuela

Neblinichthys peniculatus is described from specimens collected in the río Carapo (río Paragua - río Caroni drainage), which drains the southern flank of Cerro Guaiquinima in southeastern Venezuela. Neblinichthys peniculatusdiffers from all congeners by having mottling on the caudal peduncle consisting of dark spots and dashes (vs. caudal peduncle all about the same color or light below and dark above) and by having spots on the head (spots less conspicuous in nuptial males as the head is darker; vs. no spots). Uniquely among Neblinichthys for which nuptial males are known, the hypertrophied odontodes on the snout are rather short, none as large as the eye diameter.

A new species of the Neoplecostomine catfish Pareiorhaphis (Siluriformes: Loricariidae) from the Coastal basins of Espírito Santo, eastern Brazil

Pareiorhaphis ruschii, new species, is the first neoplecostomine catfish of the genus Pareiorhaphis described based on material from tributaries to the rio Piraquê-Açu and rio Reis Magos, both small coastal drainages in the State of Espírito Santo, eastern Brazil. The new species is promptly diagnosed from all its congeners by features related to the morphology of the lower lip margin, number of preadipose azygous plates, size and shape of the pectoral-fin spine, and caudal-fin skeleton. Additionally, sexual dimorphism of the new species is marked by hypertrophied odontodes on the lateral margins of head slightly directed forward in adult males.

Chromosomal Characterization of Armored CatfishHarttialongipinna(Siluriformes, Loricariidae): First Report of B Chromosomes in the Genus

The B chromosomes are accessory elements that are widely distributed among eukaryotic genomes and often show non-Mendelian inheritance. They are considered dispensable for the growth, development, and reproduction of organisms. Some studies have suggested that these elements may affect sex determination. Harttia is a small armored catfish genus that shows sexual dimorphism, including hypertrophied odontodes on the pectoral fin spines and along the margins of the snout in mature males. They exhibit considerable karyotypic diversity with diploid number (2n) variation and heteromorphic sex system in H. carvalhoi. To date, no occurrences of B chromosomes in the Harttia genus were detected and no relation to sexual differentiation in Neotropical fish has been determined. To determine the validity of this claim, the present paper characterized specimens of Harttia longipinna by classical and molecular cytogenetic methods. The 2n found was 58 (16m + 12sm + 16st + 14a), but of the 50 specimens analyzed (30 male and 20 female), 23 specimens (16 males and seven females) show an intra-individual from 0 to 2 micro B chromosomes. The B chromosomes were completely heterochromatic. The single NORs were shown in the first acrocentric pair with silver staining and 18S rDNA probing. FISH performed with 5S rDNA probe showed a single cistron in the proximal region of the short arm of a small metacentric pair. Thus, the cytogenetic data obtained in this study of H. longipinna highlight the karyotypic diversity found within the genus Harttia, and represent the first description of B chromosomes for this genus.

A new species of suckermouth armored catfish, Pseudancistrus kwinti (Siluriformes: Loricariidae) from the Coppename River drainage, Central Suriname Nature Reserve, Suriname

A new species of suckermouth armored catfish, Pseudancistrus kwinti, is described from the Coppename River, Suriname. It can be diagnosed from all other described Pseudancistrus by the following combination of characters: dentary papillae absent, mid-dorsal plate row complete, coloration mottled or with bars, hypertrophied odontodes along edge of snout, and weakly evertible cheek plates. It is only known from the Coppename River drainage within the Central Suriname Nature Reserve, a United Nations World Heritage Site, and one of the most pristine environments remaining on the planet. Mining, increased fishing pressure, and tourism threaten to change the region.

Description of Neblinichthys brevibracchium and N. echinasus from the upper Mazaruni River, Guyana (Siluriformes: Loricariidae), and recognition of N. roraima and N. yaravi as distinct species

Neblinichthys brevibracchium and N. echinasus are new sympatric species from upland tributaries of the Mazaruni River (Essequibo River basin) of Guyana. These two new species are the first Neblinichthys reported from Guyana. Adult males of both new species have short pectoral-fin spines and several series of hypertrophied odontodes covering the entire dorsal surface and along the entire edge of the snout. They are distinguished from each other by dorsal-fin base length/standard length (18.1-22.8% in N. brevibracchium vs. 24.3-27.0% in N. echinasus), dorsal-anal distance/SL (13.7-18.3% in N. brevibracchium vs. 11.9-12.5% in N. echinasus), by having the snout decreasing in steep arc just anterior to eyes and then flattening in area anterior of nares in N. brevibracchium vs. the snout tapering shallowly and continuously from eyes to snout tip in N. echinasus); and by having the adpressed dorsal fin reaching the anterior preadipose plate in N. brevibracchium (vs. not reaching anterior preadipose plate in N. echinasus). They are distinguished from all congeners by lacking odontodes on the opercle (vs. odontodes present); and by completely lacking an iris operculum (vs. congeners with small iris operculum present or at least dorsal portion of iris flat instead of rounded). Neblinichthys echinasus and N. brevibracchium differ from all congeners by having a spotted or vermiculated pigment pattern on the abdomen (vs. abdomen plain); in N. echinasus the abdomen is darkly pigmented with bold white spots and in Neblinichthys brevibracchium the abdomen is light-colored with gray spots and vermiculations. Neblinichthys brevibracchium and N. echinasus differ from N. roraima by having one to two preadipose plates (vs. four or more). New observations revealed Neblinichthys roraima and N. yaravi to be distinct, with N. roraima having four or more preadipose plates and N. yaravi having one or two. Both are present in the upper río Caroní, an Orinoco tributary that drains the slopes of Mount Roraima and other mountains of the Pacaraima Range in Venezuela and interdigitates with headwaters of the Mazaruni River.

Parotocinclus arandai, a new species of hypoptopomatine catfish (Siluriformes: Loricariidae) from the upper rios Jucuruçu and Buranhém, States of Bahia and Minas Gerais, Brazil

Parotocinclus arandai, new species of the hypoptopomatine catfish, is described from small creeks in the upper rios Jucuruçu and Buranhém basins, at the border of Brazilian States of Bahia and Minas Gerais. Parotocinclus arandai is distinguished from all congeners from the Atlantic coastal basins of southeastern and eastern Brazil, except Parotocinclus bahiensis, by having the branched rays and interradial membranes of the pectoral and pelvic fins unpigmented in ventral view. The new species is distinguished from most Parotocinclus species, by having a small eye, 14.8-19.3 mm HL (except P. maculicauda and P. planicauda) and by the presence of a tuft of hypertrophied odontodes on the supraoccipital (except P. cristatus and P. cesarpintoi). Parotocinclus arandai is further distinguished by having an abdomen extensively naked, with a mosaic of few rounded platelets of irregular size and distributed over the pre-anal region (except P. bahiensis, P. minutus, P. spilosoma, P. cearensis, P. cesarpintoi and P. prata). A detailed comparison with congeners on eastern Brazil hydrographical region is provided, and information on the species habitat is given.

Pseudancistrus corantijniensis, a new species from the Guyana Shield (Siluriformes: Loricariidae) with a molecular and morphological description of the Pseudancistrus barbatus group

Pseudancistrus corantijniensis is described based on specimens captured in the Corantijn River in Suriname. It is diagnosed by a particular arrangement of whitish spots, very small in the anterior three quarters of the head and large from the posterior part of the head to the caudal peduncle. As indicated by our molecular phylogeny based on mitochondrial D-loop sequences, P. corantijniensis is a member of the Pseudancistrus barbatus group comprising Guyanese derived Pseudancistrus bearing hypertrophied odontodes along the snout and nonevertible cheek plates. Other members of this group are P. barbatus, P. depressus and P. nigrescens. The closest relative to the new species is P. nigrescens, while P. barbatus and P. depressus are sister species. The known distribution range of each of the four members of the P. barbatus group is disjoint. A key is provided for the identification of the four members of the P. barbatus group.

Three new species of the armored catfish genus Loricaria (Siluriformes: Loricariidae) from river channels of the Amazon basin

Three new species of Loricaria are described from large white- and black-water river channels of the Amazon basin of Brazil, the upper rio Negro drainage of southern Venezuela, and clear waters of the lower rio Tocantins. Loricaria spinulifera and L. pumila differ from other species of Loricaria by having unique patterns of abdominal plate development and hypertrophied odontodes forming conspicuous crests on dorsal surfaces of the head and predorsal plates. Both are small species of Loricaria, reaching sexual maturity at less than 120 mm SL, and exhibiting sexually dimorphic characters consistent with members of the L. cataphracta complex. Loricaria spinulifera differs from L. pumila in having a unique arrangement of buccal papillae and large thorn-like odontodes on the dorsum of the head. Loricaria pumila is the smallest known Loricaria, reaching sexual maturity at less than 80 mm SL. Loricaria lundbergi differs from other Loricaria by having a unique abdominal plate pattern, broad head, and small basicaudal plate. Loricaria lundbergi is sympatric with L. spinulifera in the lower rio Negro drainage, but is also known from the rio Baria system of the Casiquiare drainage. Loricaria pumila occurs in the lower rio Amazonas and lower rio Tocantins. All three new species exhibit varying degrees of reduction in eye size and pigmentation seen in other fishes inhabiting deep river channels of South America.

Two new species of Isbrueckerichthys Derijst, 1996 (Siluriformes: Loricariidae) from the rio Paranapanema basin, Brazil

Two new Isbrueckerichthys species from Paranapanema river basin are described, I. saxicola and I. calvus, respectively from ribeirão Jacutinga and rio Taquara affluents. Both species present all diagnostic characters of the genus, and differ from their congeners by having bicuspid teeth (vs. simple teeth in I. alipionis), hypertrophied odontodes along the lateral margin of head (vs. hypertrophied odontodes only at the anterior portion of snout in I. epakmos) and longer pectoral-fin spine and shorter caudal peduncle length in relation to I. duseni. The new species can be distinguished from each other by number of odontodes in each minute abdominal platelet (more than six in I. saxicola vs. at most six in I. calvus); by the presence of a plated area under the three first plates of the lateral line in I. saxicola vs. its absence in I. calvus in which this region is naked; by a exposed portion of cleithrum bordering the entire margin of the opercular opening in I. saxicola vs. bordering just the superior portion in I. calvus; and by presenting the exposed surface of supraoccipital plain or slightly convex in I. saxicola vs. strongly convex with an area without odontodes on the center in I. calvus.

Pseudancistrus sidereus, a new species from southern Venezuela (Siluriformes: Loricariidae) with a redescription of Pseudancistrus

Pseudancistrus sidereus is described from two collections of specimens from Amazonas, Venezuela. Pseudancistrus sidereus differs from all other members of Pseudancistrus based on the presence of a unique keel on the caudal peduncle formed from the concave dorsal sections of the plates in the ventral series, light spots on the body (these may be yellow in life) centered on the body plates and the absence of the characteristics of the more derived members of Pseudancistrus such as hypertrophied odontodes along the snout in males and females and the loss of evertibility of the cheek plates. Pseudancistrus includes Lithoxancistrus and Guyanancistrus and is diagnosed by the following synapomorphies: no suture between pterotic-supracleithrum and hyomandibula, no contact of the hyomandibula with the prootic, straight, spoon-shaped anterior process of metapterygoid, nasal bone not much wider than laterosensory canal running through it, sphenotic not contacting posteriormost infraorbital externally, and a short ventral ridge on the pelvic basipterygium (lost in some species). Two species formerly assigned to Guyanancistrus are placed in different genera. Hypostomus guacharote is placed in Lasiancistrus and Chaetostomus trinitatis is placed in Ancistrus.