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A new species of Hemiodus is described from the Rio Xingu basin, Pará, Brazil. It is distinguished from congeners by the combination of presence of a dark longitudinal stripe extending from head to tip of lower caudal-fin lobe, an oblique blotch on dorsal-fin, 9–11 scale rows above lateral line, 58–66 perforated lateral line scales, and 17–20 circumpeduncular scales. Comments on the conservation status of the new species, as well as its relationships among Hemiodus species, are made.

A new species of Pimelodella is described from the Rio Ipitinga, Rio Jari basin, a left bank tributary of the Rio Amazonas in Brazil. The new species is diagnosed from all congeners by having a dark oval mark on the humeral region. It also differs from all congeners by a unique set of characters, including the presence of 47 to 49 total vertebrae, unpigmented areas dorsally and ventrally adjacent to the dark midlateral stripe, and maxillary barbels reaching at least to vertical through caudal fin insertion. Faunal similarities between the southern part of the eastern Guiana Shield and coastal drainages in the Guianas and Suriname are discussed.

A new species of Trachycorystes from the rio Aripuanã, above Dardanelos and Andorinhas falls, is described. The new species is distinguished from the only other species of the genus, T. trachycorystes, by the following characteristics: jaws of equal length (vs. lower jaw prognathous in T. trachycorystes); skull roof covered by thick (vs. thin) integument; inner mental barbel very thin and short not reaching base of outer barbel (vs. extending to or beyond base of outer mental barbel); dorsal-fin spine serrated posteriorly, smooth or rough anteriorly (vs. serrated anteriorly and smooth or rough posteriorly); caudal fin shallowly forked (vs. emarginate); and gas bladder simple, without diverticula (vs. with three posterior diverticula). Comments and data on the nominal species Trachycorystes trachycorystes are provided. Trachycorystes cratensis Miranda Ribeiro, 1937, is allocated to the genus Trachelyopterus Valenciennes, 1840, and another local catfish species, Parotocinclus aripuanensis Garavello, 1988, has its type locality reassigned. Descreve-se uma espécie nova de Trachycorystes proveniente do curso superior do rio Aripuanã, acima das cachoeiras Dardanelos e Andorinhas. A espécie nova diferencia-se da outra espécie do gênero, T. trachycorystes, pelos seguintes caracteres: maxilas de mesmo comprimento, isto é, mandíbula não prognata (vs. mandíbula prognata em T. trachycorystes); teto do crânio coberto com pele espessa (vs. fina); barbilhão mental muito fino e curto não alcançando a base do barbilhão pós-mental (vs. estendendo-se até a base do barbilhão pós-mental ou além); espinho da nadadeira dorsal com a borda anterior lisa ou rugosa e a posterior com serras retrorsas (vs. borda anterior com serras e a posterior lisa ou rugosa); nadadeira caudal bifurcada (vs. emarginada); bexiga natatória simples, sem divertículos (vs. com três divertículos posteriores). Comentários e dados sobre as outras espécies nominais de Trachycorystes são apresentados. Trachycorystes cratensis Miranda Ribeiro, 1937, é transferido para o gênero Trachelyopterus Valenciennes, 1840, e retificam-se dados sobre a localidade-tipo de Parotocinclus aripuanensis Garavello, 1988.

Myxiops aphos, new genus and species, is described from a river in the eastern portion of Bahia State, Brazil. Myxiops is distinguished from all other characid genera by the combination of the following features: infraorbitals fused in a unique fashion, resulting always in less than six autogenous bones; a single tooth row in the premaxilla; presence of somewhat pedunculate teeth, expanded and compressed distally, with cusps similar in shape and perfectly aligned along distal margin; ventral margin of toothed portion of maxillary curved towards ventral margin of premaxilla and maxillary teeth forming a continuous series with premaxillary teeth; margins of pre- and postzygapophyses with projections anteriorly and posteriorly directed; accumulation of epithelial cells forming globular structures distributed over head and scales; and base of anal fin without scales covering basal portion of unbranched and anterior branched rays. The presence of these features in other characids is discussed. Myxiops aphos, novo gênero e espécie, é descrita de um rio do leste do Estado da Bahia, Brasil. Myxiops distingue-se de todos os outros gêneros de caracídeos pela seguinte combinação de caracteres: exclusivo modo de fusão dos infraorbitais, resultando em menos de seis ossos autógenos; uma única série de dentes no pré-maxilar; presença de dentes comprimidos com cúspides similares em tamanho e alinhadas ao longo da margem distal dos dentes; margem ventral da porção com dentes do maxilar arqueando-se em direção à margem ventral do pré-maxilar e dentes do maxilar formando um eixo contínuo com os dentes do pré-maxilar; margens das pré- e pós-zigapófises com projeções anterior e posteriormente direcionadas; acúmulo de células epiteliais formando estruturas globulares distribuídas sobre a cabeça e escamas; e base da nadadeira anal sem escamas. A presença destas características em outros caracídeos é discutida.

Centromochlus actually comprises eleven species, being the most problematic genus among the Centromochlinae, including morphologically heterogeneous taxa. The Centromochlus species have a wide distributional area on northern South America. Centromochlus meridionalis, new species, is described from headwaters of rio Teles Pires, contributor of rio Tapajós, Mato Grosso State, Brazil, and represents one of the southernmost records of a centromochlin catfish for Meridional Amazon rivers. Centromochlus meridionalis is promptly distinguished from its congeners by the small orbital diameter (relative to head length), and also by the combination of absence of first nuchal plate, anterior margin of dorsal-fin spine smooth, six branched rays in anal fin, seven pairs of ribs and 34 vertebrae. They are small sized catfishes with adults between 33 to 61 mm in standard length. The modified male anal fin is conspicuous, with the third unbranched ray enlarged, about twice the width of first unbranched ray. The new species inhabits a region strongly endangered by environmental changes due to expansion of agropecuary activities on Brazilian Amazon, which include this species in an uncertain situation regarding the conservation status of its natural population. Centromochlus abriga atualmente onze espécies, sendo o gênero mais problemático dentre os Centromochlinae, incluindo táxons morfologicamente heterogêneos. As espécies de Centromochlus apresentam uma ampla área de distribuição no norte da América do Sul. Centromochlus meridionalis, espécie nova, é descrita para as cabeceiras do rio Teles Pires, formador do rio Tapajós, Mato Grosso, Brasil, e representa um dos registros mais ao sul de um bagre centromoclíneo para os riachos da Amazônia meridional. Centromochlus meridionalis é prontamente distinguido de todos os seus congêneres, pelo diâmetro orbital pequeno (em relação ao comprimento da cabeça), e ainda pela combinação da ausência de primeira placa nucal, margem anterior do espinho da nadadeira dorsal lisa, seis raios ramificados na nadadeira anal, sete pares de costelas e 34 vértebras. São bagres de pequeno porte com adultos entre 33 e 61 mm de comprimento padrão. A nadadeira anal de machos sexualmente maduros é conspicuamente modificada, na qual o terceiro raio indiviso é muito largo, cerca do dobro da espessura do primeiro raio ramificado. O registro desta espécie nova ocorre em uma região fortemente ameaçada por alterações ambientais decorrentes da expansão de atividades agropecuárias na Amazônia Brasileira, a qual coloca esta espécie em uma situação incerta quanto ao estado de conservação da sua população natural.

Hypostomus interruptus (Miranda-Ribeiro) (Fig. 5, 6; Table 2) Plecostomus interruptus Miranda-Ribeiro, 1918:632 (type locality: rio Juqui��. Restricted by Britski, 1969:209 to rio Juqui��, Fazenda Po��o Grande). Gosline, 1945:81 [reference, distribution]. Fowler, 1954:184 [reference, distribution]. Britski, 1969:209 [catalogue, distribution]. Hypostomus interruptus Isbr��cker, 1980:25 [reference, distribution]. Burgess, 1989:431 [reference, distribution]. Isbr��cker, 2001:28 [reference]. Weber, 2003:358 [reference, distribution]. Armbruster, 2004:79 [reference]. Hypostomus cf. affinis (Steindachner, 1877). Bizerril & Lima, 2000:107 [reference]. Hypostomus sp. 1161 Montoya-Burgos, 2003 [biogeography, molecular phylogeny]. Holotype. Brazil. S��o Paulo: MZUSP 2110, 121.0 mm SL; rio Juqui��, Fazenda Po��o Grande, Juqui��; W. J. Moenkhaus, 1898. Other material examined. Brazil. S��o Paulo: - MZUSP 68172, 2, 166.0 - 202.8 mm SL; rio do Queimado, tributary of rio Jacupiranguinha, Parque Estadual do Jacupiranga, approx. 24�� 48' 2,2"S, 48�� 13' 32,0"W, Cajati; Projeta Biota/Fapesp Ribeira, 9 March 2001. - MZUSP 68192, 4, 32.3-46.6 mm SL; MZUSP 68196, 7, 32.4-55.7 mm SL; same data as above. - MZUSP 75463, 7, 41.8 - 140.0 mm SL; ribeir��o Bra��o Bonito, tributary of rio Areado, Parque Estadual da Serra do Mar, N��cleo Pedro de Toledo, approx. 24�� 14' 59"S, 47�� 10' 46"W, Itariri; Projeta Biota/Fapesp Ribeira, 13 September 2001. - MZUSP 75464, 3, 42.7-77.1 mm SL; Ribeir��o Bra��o Bonito, tributary of rio Areado, Parque Estadual da Serra do Mar, N��cleo Pedro de Toledo, approx. 24�� 15' 5,0"S, 47�� 10' 35,0"W, Itariri; Projeta Biota/Fapesp Ribeira, 13 September 2001. - MZUSP 78706, 1, 33.5 mm SL; Ribeir��o Grande creek, Bairro Ribeir��o Grande, Parque Estadual da Serra do Mar, N��cleo Pedro de Toledo, approx. 24�� 14' 7;0"S, 47�� 13' 58,0"W, Pedro de Toledo; Projeta Biota/Fapesp Ribeira, 11 September 2001. - MZUSP 78707, 1, 54.0 mm SL; tributary of rio Itariri, on the road from Manoel da N��brega to Santa Rita, approx. 24�� 12' 37,0"S, 47�� 17' 23,0"W, Pedro de Toledo; Projeta Biota/Fapesp Ribeira, 14 September 2001. - MZUSP 51913, 4 (2), 104.3-108.9 mm SL; rio Saibadela, Saibadela Base Camp of Fazenda Intervales, Sete Barras; S. Buck et al., 4-6 March 1994. - MZUSP 70693, 1, 43.5 mm SL; rio das Criminosas, tributary of rio Catas Altas, Itapirapu�� Paulista, approx. 24 �� 34' 16,7"S, 48�� 10' 22,4"W; Projeto Biota/Fapesp Ribeira, 09 August 2001. - MZUSP 37992, 1, 149.0 mm SL; rio Pardo, tributary of rio Turvo, ��gua do Padre district, Barra do Turvo; O. T. Oyakawa et al., 22 July 1987. - MZUSP 40003, 4, 83.7-96.5 mm SL; riacho Arataca, tributary of rio Jacupiranga, at road Pariquera - A��u to Iguape, Pariquera-A��u; O. T. Oyakawa et al., 28 March 1987. - MZUSP 45410, 1, 117.0 mm SL; rio Pil��es, tributary of rio Ribeira de Iguape, Eldorado; M. Damato, 7 March 1993. - MZUSP 45457, 1, 202.3 mm SL; rio Ribeira de Iguape, close to rio Batatal, Eldorado; M. Damato, 5 March 1993. - MZUSP 51981, 21 (5), 75.9-169.4 mm SL; rio Betari, Serra district, Iporanga; R. Pardini, 16 February 1995. - MZUSP 52636, 2, 116.5-180.5 mm SL; rio Betari, bellow rio ��guas Quentes, ��guas Quentes cave, Serra district, Iporanga; S. Buck et al., 26 January1995. - MZUSP 52639, 3, 141.3-178.0 mm SL; rio Betari, Serra district, Iporanga; S. Buck et al., February 1995. - MZUSP 52455, 1, 124.0 mm SL; rio Ribeira de Iguape, close to rio Batatal, Eldorado; M. Damato, 5 March 1993. - MZUSP 46066, 7, 75.9-120.7 mm SL; rio Betari, Iporanga; R. Pardini, 1993. - MZUSP 50715, 3, 118.5-150.0 mm SL; rio Betari, near of rio Ribeira de Iguape, Iporanga; S. Buck, February 1995. - MZUSP 45168, 1, 168.6 mm SL; rio Batatal, tributary of rio Ribeira de Iguape, Eldorado; M. Damato, 3 March 1993. - MZUSP 55486, 1, 192.5 mm SL; rio Pil��es, tributary of rio Ribeira de Iguape, Iporanga; M. R. Santos & M. Morato, 19 January 1995. - MZUSP 55217, 3, 206.1-226.8 mm SL; rio Pardo, Barra do Turvo; M. R. Santos & C. E. Esp��rito Santo, October 1995. - MZUSP 55214, 5, 172.8-197.2 mm SL; rio Catas Altas, Ribeira; M. R. Santos & M. Morato, 23 January 1995. - MZUSP 55487, 2, 156.5-188.8 mm SL; rio Batatal, Eldorado; M. R. Santos & M. Morato, 17 January 1995. - MZUSP 55482, 2, 155.4-189.2 mm SL; rio Pardo, Barra do Turvo; M. R. Santos & M. Morato, 25 January 1995. - MZUSP 55488, 16, 115.1-223.7 mm SL; waterfalls of rio Palmital, 1000 m above mouth into rio Ribeira de Iguape, Apia��; M. R. Santos & M. Morato, 22 January 1995. Paran��: - MZUSP 25010, 10, (5), 125.3-180.8 mm SL; Capivari-Cachoeira Dam, Campina Grande do Sul; L. C. Freitas, 26 August 1977. - MZUSP 54581, 236.0 mm SL; rio Pardo, Bairro ��gua do Padre on the road Iporanga to Barra do Turvo, Barra do Turvo; O. T. Oyakawa, F. Langeani & V. C. Silva, February 1988. - MZUSP 79558, 49, 21.2- 39.1 mm SL, Arroio Taquaral, tributary of rio A��ungui, Campo Largo, 25�� 24' 50.3" S, 49�� 38' 31.8" W; Projeto Biota/Fapesp Ribeira, 19 May 2002. - MZUSP 79559, 9, 30.5-47.5 mm SL; Arroio 3 Barras, tributary of rio Ponta Grossa, 24�� 50' 14.8"S, 49�� 15' 51.2"W; Cerro Azul; Biota/Fapesp Ribeira, 20 May 2002. Diagnosis. Hypostomus interruptus is distinguished from its congeners inhabiting rio Ribeira de Iguape basin by its oblique dark bands on flanks (versus absence of such bands), comparatively smaller spots over body and fins, more so over anterior portion of head, and spots on region of trunk posterior to dorsal-fin end more conspicuous in smaller specimens (up to 130.0 mm SL), becoming faded or absent in larger specimens (versus color pattern of trunk relatively homogeneous throughout ontogeny). Description. Standard length of examined specimens 32.3 to 236.0 mm SL. Counts and proportional measurements presented in Table 2. Dorsal profile gently raising upwards from snout tip to dorsal-fin origin and gently descending from this point to the end of caudal peduncle. Caudal peduncle roughly oval in cross-section, flattened on ventral portion. Dorsal plates between end of dorsal-fin base and adipose-fin spine flattened. One preadipose plate. Pre-dorsal region of trunk located between pterotic-supracleithrum and vertical through dorsal-fin origin covered by three horizontal series of plates that extends posteriorly to caudal fin. Median series of plates bearing the lateral-line canal. Mid-dorsal series situated above and mid-ventral series situated below median series. Dorsal series of plates starting at dorsal-fin origin. Ventral series of plates starting approximately at midlength of pelvic-fin base extension. Plates of mid-dorsal series not aligned, interrupted by first plate of dorsal series (Fig. 1B). Covering of abdomen ontogenetically variable. Plates restricted to central area of abdomen in specimens up to 95.0 mm SL; in larger specimens abdomen usually covered with minute platelets, leaving a naked area just around the pelvic fin. Plates on dorsal and lateral portion of body relatively smooth in small and median size specimens. Trunk plates of larger specimens with relatively well developed ridges, forming four keels along flanks. Dorsal-most keel located over dorsal series of plates. Keel on mid-dorsal series of plates interrupted, following the alignment of plates. Anterior portion of this keel somewhat continuous with ridge on pterotic-supracleithrum, crossing the middorsal series of plates on pre-dorsal region of trunk, and not aligned to keel of posterior portion of mid-dorsal series. Keel on median series of plates poorly developed. Keel on three dorsal-most horizontal series of plates usually starting at dorsal-fin origin, except by largest specimens examined that have those keels more conspicuous posterior to the vertical through insertion of sixth branched dorsal-fin ray. Mid-ventral keel well developed, more conspicuous on anterior half of trunk. Head somewhat triangular, rounded anteriorly. Dorsal and ventral region of head completely covered with dermal ossifications, except for a small oval naked area on snout tip. Outer face of upper lip covered with small platelets, except small specimens that have most of this region naked (smaller than 100.0 mm SL). Ornamentation of pterotic-supracleithrum similar to the remaining surface of head and with odontodes densely distributed. Dorsal margin of orbit slightly elevated, continuing in a low ridge on pterotic-supracleithrum. Larger specimens with a low ridge on supraoccipital, diverging in two weakly developed separated ridges on predorsal plates. Usually two plates, sometimes one, bordering posterior margin of the supraoccipital bone. Space between orbits almost straight or slightly convex. Eyes large. Mouth wide, rounded. Anterior-most papillae of inner face of lower lip irregular in form, somewhat elongate, followed by roundish papillae decreasing in size posteriorly. Teeth long and bicuspid; medial cusp approximately twice in length of outer cusp and curved inwards. Premaxillary teeth inserted in a relatively straight line; dentary teeth inserted in a concave arch facing mouth cavity; contralateral dentaries forming a relatively wide angle. Maxillary barbels relatively thin, elongated, slightly shorter than eye diameter, and without papillae. Dorsal-fin origin situated on vertical anterior to pelvic-fin origin, approximately on posterior third of pectoral-fin spine. Dorsal fin relatively small; tips of adpressed last two rays ending on second or third plate anterior to adipose-fin spine. Margin of dorsal fin relatively straight. Adipose-fin spine compressed, moderately strong with posterior-most portion curved ventrally in specimens around 150.0 mm SL and straight in smaller specimens. Distal half of pectoral-fin spine of larger specimens covered dorsally with small odontodes slightly curved forward (larger than 110.0 mm SL). Tip of adpressed pectoral fin beyond origin of pelvic fin. Tip of adpressed pelvic-fin spine reaching origin of anal fin in larger specimens and posterior to origin of the last branched ray in small specimens (up to 180.0 mm SL). Basal lamina of first proximal radial of anal fin covered by skin in the majority of specimens examined, except in a few small specimens. Caudal fin margin concave, lower spine slightly longer than upper. Color in alcohol. Dorsal and lateral surface of body with light brown or grayish ground coloration. Relatively small black or dark-brown roundish spots scattered all over dorsal and lateral surface of body, becoming gradually smaller towards anterior portion of head. Spots on region of trunk posterior to dorsal-fin end more conspicuous in smaller specimens (up to 130.0 mm SL), becoming faded or absent in larger specimens. Lateroventral portion of body below mid-ventral series of plates without spots on specimens 150.0 mm SL or larger. Four dark brown inconspicuous oblique bands on flanks, more visible in juveniles; dorsal portion of anterior-most band aligned with base of first three branched dorsal-fin rays; anterodorsal margin of second band aligned with insertion of last one or two dorsal-fin rays; third band located immediately posterior to dorsal-fin end and last band over posterior portion of caudal peduncle. Ventral surface of body pale or yellowish, usually clear except in some juveniles that have the ventral surface scattered with spots similar to those on body. Overall ground coloration of all fins pale to yellowish; recently fixed specimens pale orange. Dark brown or black spots larger than those of body sparsely distributed over fin rays and interradial membranes; pattern of distribution usually forming series when fins erected in specimens 180.0 mm SL or smaller. Caudal-fin spots arranged in irregular vertical series. Ground color of living specimens usually darker than alcohol preserved specimens and pattern of the four oblique bands more conspicuous. Distribution and notes. Hypostomus interruptus is known to occur only in Ribeira de Iguape river basin. Sampling efforts in this region in the last ten years suggests Hypostomus interruptus as the most common Hypostomus in the area. This conclusion involves the high number of individuals collected, high diversity of environments inhabited, and wide geographical distribution of this species (Fig. 5). Hypostomus interruptus was found in relatively large rivers as exemplified by the rivers Ribeira, Pil��es, Catas Altas, Pardo, and also in smaller drainages as Betari, Saibadela, Arataca, a tributary of rio Jacupiranga, and Bra��o Bonito, a tributary of rio S��o Louren��o. The area of occurrence of H. interruptus varies from 165 to 900 m above sea level., Published as part of Osvaldo T. Oyakawa, Alberto Akama & Angela M. Zanata, 2005, Review of the genus Hypostomus Lac��p��de, 1803 from rio Ribeira de Iguape basin, with description of a new species (Pisces, Siluriformes, Loricariidae)., pp. 1-27 in Zootaxa 921 on pages 14-18

Hypostomus punctatus: Brazil. Rio de Janeiro: - MZUSP 80305, 6, 40.3-109.6 mm SL; rio S��o Jo��o, on the road Boqueir��o to Japu��ba., Published as part of Osvaldo T. Oyakawa, Alberto Akama & Angela M. Zanata, 2005, Review of the genus Hypostomus Lac��p��de, 1803 from rio Ribeira de Iguape basin, with description of a new species (Pisces, Siluriformes, Loricariidae)., pp. 1-27 in Zootaxa 921 on page 26

Key to the species of Hypostomus from rio Ribeira de Iguape basin 1. Keels absent or poorly developed; anterior plates of mid-dorsal series longitudinally aligned with those of posterior portion of trunk, not interrupted by the first plate of dorsal series (Fig. 1A); caudal peduncle trapezoid in cross-section; 3 to 5 plates around supraoccipital (Fig. 2)............................................................ Hypostomus agna 1’. Keels well developed; anterior plates of mid-dorsal series not aligned with those of posterior portion of trunk, interrupted by the first plate of dorsal series (Fig. 1B); caudal peduncle ovoid in cross-section; 1 to 2 plates around supraoccipital.....................2 2. Plates on ventral surface of head absent in adults; spots on posterior half of body less conspicuous and more sparsely distributed than on anterior portion of body; spots on fins usually aligned, sometimes forming dark bands (Fig. 4).................. Hypostomus ancistroides 2’. Ventral region of head completely covered with dermal ossifications, except for small naked areas; pattern of distribution of spots on body and fins relatively uniform, never forming dark bands.......................................................................................................3 3. Presence of oblique inconspicuous dark bands on flanks; small spots over body and fins, smaller over head; dorsal fin comparatively smaller (dorsal-fin spine length 21.6 -28.4% SL) (Fig. 6)................................................................. Hypostomus interruptus 3’. Dark bands on flanks absent; well defined large, dark, and roundish spots somewhat homogeneously distributed over body and fins; relatively broad dorsal-fin (dorsal-fin spine length 27.6-34.3% SL) (Fig. 7).................................. Hypostomus tapijara, sp.n.

Hypostomus auroguttatus: Brazil. Minas Gerais: - MZUSP 66206, 1, 116.7 mm SL; rio Gl��ria, tributary of rio Muria��, Muria��. - MZUSP 66205, 2, 161.0 - 220.0 mm SL; rio Gl��ria, tributary of rio Muria��, Muria��. - MZUSP 66207, 2, 194.0-197.0 mm SL; rio Sua��u�� Grande, Pe��anha. - MZUSP 66208, 1, 204.0 mm SL; rio Sua��u�� Grande, S��o Pedro do Sua��u��. Rio de Janeiro: - MZUSP 66213, 1, 188.0 mm SL; rio Para��ba do Sul, Ilha dos Pombos, Carmo. - MZUSP 44512, 1, 79. 0 mm SL; rio Pirapitinga, first bridge on road from Capelinha to Mau��, Bairro da Capelinha, Resende. - MZUSP 45406, 1, 158.0 mm SL; rio Para��ba do Sul, S��o Fid��lis., Published as part of Osvaldo T. Oyakawa, Alberto Akama & Angela M. Zanata, 2005, Review of the genus Hypostomus Lac��p��de, 1803 from rio Ribeira de Iguape basin, with description of a new species (Pisces, Siluriformes, Loricariidae)., pp. 1-27 in Zootaxa 921 on page 25