Descriptions of five new species of the neotropical cichlid genus Gymnogeophagus Miranda Ribeiro, 1918 (Teleostei: Cichliformes) from the rio Uruguay drainage

Gymnogeophagus is a Neotropical cichlid genus distributed in the río Paraguay, rio Paraná and rio Uruguay drainages and also in the coastal rivers of Uruguay and southern Brazil. Its monophyly is supported by two derived features: the absence of supraneurals and the presence of a forward spine in the first dorsal-fin pterygiophore. Herein, five new species of Gymnogeophagus are described from middle to upper tributaries of the rio Uruguay drainage and from the rio Negro. All these new species belong to a clade, which includes G. gymnogenys , easily recognized by sharing two synapomorphies: the absence of an oblique bar between the dorsal border of the eye and the nape, and the possession of a black bar originating in the dorsal contour near the dorsal-fin origin and directed downward and backward on the dorsum. A key to all species of Gymnogeophagus is provided.

Gymnogeophagus é um gênero Neotropical de ciclídeos que ocorre nas drenagens dos rios Paraguay, Paraná e Uruguay e também em rios costeiros do Uruguay e do sul do Brasil. A monofilia do gênero é baseada em duas sinapomorfias: a ausência de supraneurais e a presença de um espinho dirigido para frente no primeiro pterigióforo da nadadeira dorsal. Neste trabalho são descritas cinco espécies novas de Gymnogeophagus de afluentes do médio ao alto rio Uruguai e rio Negro. Todas as espécies pertencem a um clado que inclui G. gymnogenys , facilmente reconhecido pelo compartilhamento de duas sinapomorfias: a ausência da barra cinza escura oblíqua entre a margem dorsal da órbita e a margem dorsal da cabeça, e a presença de uma barra cinza escura originando-se no dorso, anteriormente à nadadeira dorsal e direcionada para trás e para baixo na lateral do corpo. É fornecida uma chave de identificação para todas as espécies de Gymnogeophagus.

Phylogenetic diagnosis and expanded description of the genus Mazarunia Kullander, 1990 (Teleostei: Cichlidae) from the upper Mazaruni River, Guyana, with description of two new species

We expand the description of the genus Mazarunia Kullander, 1990, explore morphological diagnostic characters for the genus and for its sister-group relationship with Guianacara Kullander & Nijssen, 1989 in a phylogenetic context, expand the description of M. mazarunii and describe two new species. Mazarunia can be diagnosed by the combination of numerous anatomical traits, including the unique loss of infraorbital 6, the configuration of the first epibranchial in two of the species, a well-developed posteroventral lateral expansion of the palatine that is largely contiguous with the ectopterygoid, the absence of a suture between the hyomandibular and the metapterygoid, the absence of an interarcual cartilage, fourth ceratobranchial with 2 or 3 tooth plates, a caudally scaled interoperculum, equal-sized scales in the ventral and lateral chest regions, a simple, disjunct pattern of lateral line squamation, and smooth preopercle, supracleithrum and extrascapula. Species of Mazarunia can be further distinguished from species of their sister-genus Guianacara by their distinct color patterns. Mazarunia charadrica, new species, can be distinguished from other species of Mazarunia, among other characters, by approximately equal uncinate process and anterior arm and reduced anteroventral expansion of epibranchial 1 (vs. uncinate process narrower and complete anteroventral expansion in the other two species), a dorso-ventrally flattened maxillary process of the palatine (vs. cylindrical in the other two species), cycloid (vs. ctenoid) scales in the opercular, postorbital, lateral chest and anal-genital regions, the absence of a mid-lateral spot, and a diffuse dark area covering the dorsal portion of the head giving the impression of a "black cap". Mazarunia charadrica has a unique juvenile pattern of seven vertical dark bars partially preserved in adults. Bars 3-6 in antero-caudal direction are most visible in juveniles and medium-sized specimens but become fainter and almost disappear in adults. Many specimens show only bar number 3 (midlateral bar). Mazarunia mazarunii can be distinguished from all other species of Mazarunia by the presence of two foramina (vs. one) on the lateral face of the ascending process of the premaxilla, a lachrymal bone that is longer than deep (vs. deeper than long), an infraorbital 3 that is contiguous but not overlapping with the lachrymal (vs. overlapping), ctenoid scales (vs. cycloid) on the subopercle, interopercle and chest, and by its unique coloration, including complete suborbital and supraorbital stripes, and being the only species of Mazarunia with a discernible lateral band formed by the mid-line blotching pattern associated with lateral bars. In large adults, M. mazarunii has a black or dark bar behind the head that produces the impression of a collar. Mazarunia pala, new species, can be distinguished from its congeners by the absence of a parhypurapophysis, the presence of a dorsal-fin scaly pad with ctenoid scales (vs. no scaly pad in M. charadrica and M. mazarunii), a small suborbital stripe limited to the preopercle, the absence of clearly discernible lateral bars on the body, and by its general pinkish coloration with midlateral spot as the only melanic marking. All known species of Mazarunia are restricted to the upper reaches of the Mazaruni River basin in Guyana.(AU)

Expandimos la descripción del género Mazarunia, exploramos caracteres diagnósticos morfológicos para el género y su relación de grupo hermano con Guianacara en un contexto filogenético, expandimos la descripción de M. mazarunii y describimos dos nuevas especies. Mazarunia se puede diagnosticar por la combinación de numerosos atributos anatómicos, incluyendo la pérdida del infraorbital 6, la configuración del primer epibranquial en dos de las especies, una expansión posteroventral lateral del palatino bien desarrollada y mayormente continua con el ectopterigoide, la ausencia de sutura entre la hiomandíbula y el metapterigoide, la ausencia del cartílago interarcual, 2 a 3 placas dentadas en el cuarto ceratobranquial, la porción caudal del interopérculo escamada, escamas de igual tamaño en el flanco y la región lateral del pecho, un patrón simple y disjunto de escamación en la línea lateral, y preopérculo, supracleitro y extra escápula lisos. Además, todas las especies de Mazarunia se pueden distinguir de especies en su género hermano Guianacara por diferencias de coloración. Mazarunia charadrica, especie nueva, puede distinguirse de otras especies de Mazarunia, entre otros caracteres, por tener un proceso uncinado aproximadamente igual al brazo posterior y expansión anteroventral reducida en el epibranquial 1 (contra proceso uncinado más angosto y expansión anteroventral completa en las otras dos especies), el proceso maxilar del palatino aplanado dorsoventralmente (contra cilíndrico en las otras dos especies), escamas cicloides (contra ctenoides) en las regiones opercular, postorbital, pectoral lateral y génito-anal, la ausencia de mancha mediolateral, y un área oscura difusa cubriendo la porción dorsal de la cabeza dando la impresión de un "sombrero negro". Mazarunia charadrica tiene un patrón único de coloración juvenil con siete barras verticales conservadas parcialmente en los adultos. Las barras 3-6 en dirección anterocaudal son más ...(AU)

Guianacara dacrya, a new species from the rio Branco and Essequibo River drainages of the Guiana Shield (Perciformes: Cichlidae)

Describimos una especie nueva de Guianacara de las cuencas del río Essequibo y el río Branco en Guyana y el norte de Brasil. Guianacara dacrya, especie nueva, puede distinguirse de todos sus congéneres por la presencia de una barra infraorbital modificada y por la forma única del margen lateral de la placa dentada de la mandíbula faríngea inferior. Adicionalmente, Guianacara dacrya se distingue de G. stergiosi, G. owroewefi, G. sphenozona y G. geayi por poseer una barra medio-lateral fina, de G. cuyunii por poseer membranas branquistegales grises y de G. oelemariensis por poseer dos supraneurales. La especie nueva se distingue de la mayoría de sus congéneres por la presencia de manchas blancas en la porción espinosa de la aleta dorsal, la posición de la mancha medio-lateral, la presencia de filamentos en la aleta dorsal, anal y en algunos casos en la caudal, y de al menos las especies venezolanas por varias características morfométricas. Guianacara dacrya se conoce de las cuencas del ríos Essequibo, Takutu e Ireng en Guyana y posiblemente del río Uraricoera en la cuenca del río Branco en Brasil. Se presenta una clave de especies.

A new species of Guianacara is described from tributaries of the Essequibo River and the rio Branco in Guyana and northern Brazil. Guianacara dacrya, new species, can be diagnosed from all congeners by the possession of a unique infraorbital stripe and by the shape of the lateral margin of the lower pharyngeal jaw tooth plate. Guianacara dacrya can be further distinguished from G. geayi, G. owroewefi, G. sphenozona and G. stergiosi by the possession of a thin midlateral bar, from G. cuyunii by the possession of dusky branchiostegal membranes and from G. oelemariensis by the possession of two supraneurals. This species differs from most congeners by the presence of white spots on the spiny portion of the dorsal fin, the placement of the midlateral spot, the presence of filaments on the dorsal, anal and in rare cases the caudal-fin and from at least the Venezuelan species by several morphometric variables. Guianacara dacrya is known from the Essequibo, Takutu and Ireng River basins of Guyana and possibly from the rio Uraricoera in the rio Branco basin in Brazil. A key to the species is provided.