Anatomical characterization of the digestive system of the pufferfish (Chilomycterus spinosus spinosus)

Descriptive studies of the fish digestive system are fundamental because they provide information on the biology of the species. Thus, the objective of this study was to morphologically describe the digestive system of the pufferfish, Chilomycterus spinosus spinosus. For this, adult specimens of pufferfish (n = 10) of both sexes were used. The animals were fixed with 10% aqueous formaldehyde solution, dissected, analyzed descriptively and photographed. The results demonstrate that the pufferfish has a morphologically modified digestive system, which is adapted to the defense behavior. This species presents a pouch-shaped diverticulum, that is called abdominal pouch, which allows the expansion of the celomatic cavity and the temporary storage of food. Although it is used to store food, macroscopically the abdominal pouch does not show gastric folds. However, this absence is compensated by a small intestine containing innumerable villi.

Cucullanus marajoara n. sp. (Nematoda: Cucullanidae), a parasite of Colomesus psittacus (Osteichthyes: Tetraodontiformes) in the Marajó, Brazil / Cucullanus marajoara n. sp. (Nematoda: Cucullanidae), um parasito de Colomesus psittacus (Osteichthyes: Tetraodontiformes) no Marajó, Brasil

Abstract Cucullanus marajoara n. sp. (Cucullanidae) is reported to parasitize Colomesus psittacus (Tetraodontiformes), which is a fish species from the Marajó Archipelago, state of Pará, estuarine region of the Brazilian Amazon. The new species differs from similar species by the presence of a protruding upper lip on the cloacal opening, the distribution of the cloacal papillae: five pre-cloacal papillae pairs and 5 are ventral and located posteriorly to the pre-cloacal sucker and an unpaired papilla is located on the upper cloacal lip and five post-cloacal pairs, and a pair of lateral phasmids located between papillae pairs. Additionally, Cucullanus marajoara n. sp. is compared to other species of this genus described in Brazil, particularly Cucullanus ageneiosus and Cucullanus oswaldocruzi, which both occur in the same zoogeographic region of this study but parasitize fish of a different order (Siluriformes). Cucullanus dodsworthi and Cucullanus brevicaudatus are the only described species parasitizing fish of the order Tetradontiformes in Brazil, and the new species differs from these species by the distribution of the cloacal papillae and the host habitat. The description of Cucullanus marajoara n. sp. adds data to the biodiversity of described parasites that parasitize Tetradontiformes of the estuarine ichthyofauna in the Brazilian Amazon.

Resumo Cucullanus marajoara n. sp. (Cucullanidae) é descrita parasitando Colomesus psittacus (Tetraodontiformes) peixe do arquipélago de Marajó, Estado do Pará, região estuarina da Amazônia brasileira. A nova espécie difere de seus congêneres por apresentar lábio superior da abertura cloacal protrudente e na distribuição de papilas cloacais: 5 pares pré-cloacais, e uma papila não pareada no lábio superior da cloaca e 5 pares pós-cloacais, um par de fasmídeos laterais. Além disso, Cucullanus marajoara n. sp. é comparada com outras espécies do gênero descritas no Brasil, em especial Cucullanus ageneiosus e Cucullanus oswaldocruzi, ambos parasitos de peixes da ordem Siluriformes; porém, ocorrendo na mesma região zoogeográfica deste estudo, diferem da ordem do hospedeiro da nova espécie (Tetraodontiformes). Cucullanus dodsworthi e Cucullanus brevicaudatus são as únicas espécies descritas parasitando peixe da ordem Tetradontiformes no Brasil, e a nova espécie difere dessas na distribuição das papilas cloacais e habitat dos hospedeiros. Cucullanus marajoara n. sp. adiciona dados a biodiversidade de parasitos descritos parasitando Tetradontiformes da ictiofauna estuarina da Amazônia brasileira.

Ecología trófica del pez Arothron meleagris (Tetraodontiformes: Tetraodontidae) en el arrecife de Los Frailes, Baja California Sur, México

Trophic ecology of the fish Arothron meleagris (Tetraodontiformes: Tetraodontidae) from Los Frailes reef, Southern Baja California, Mexico. Monthly samples were taken from November 2004 to October 2005 in the Los Frailes reef, BCS, Mexico. The objective was to determine the feeding habits of the pufferfish, Arothron meleagris, as well as possible variations in feeding patterns due to size and/or sex. We captured 101 specimens, with all stomachs contained food. The index of relative importance (IRI) was used to determine the main items; which were non-identified organic matter (NIOM) (30.44%), Echinometra vanbrunti (26.25 %), Porifera (12.63 %), Pocillopora spp. (11.84%), Bryozoa (5.37 %) and Porites spp. (4.83 %). Levin’s index indicated a low trophic niche breadth (Bi= 0.12) and allowed us to determine that A. meleagris is a specialist predator with strong preferences towards certain food types. The Morisita-Horn index showed a high trophic overlap between sexes ( or = 0.78), seasons (hot and cold or = 0.95) and among sizes (small and medium or = 0.94; small and large or = 0.74; medium and large or = 0.83). Rev. Biol. Trop. 57 (1-2): 113-123. Epub 2009 June 30.

Con la finalidad de determinar los hábitos alimenticios del tamboril de oro Arothron meleagris, así como sus posibles variaciones de alimentación por talla y sexo, se realizaron muestreos mensuales de noviembre 2004 a octubre 2005, en el arrecife de Los Frailes, Baja California Sur, México. Se capturaron un total de 101 ejemplares, en los cuales todos los estómagos contenían alimento. Se aplicó el índice de importancia relativa (IIR) para determinar los principales categorías alimenticias (ítems), los cuales fueron: Echinometra vanbrunti (26.25 %), Porifera (12.63 %), Pocillopora spp. (11.84%), Bryozoa (5.37 %) y Porites spp. (4.83 %). El índice de Levin indica baja amplitud del nicho trófico (Bi= 0.12) por lo que se le puede considerar como un depredador especialista con marcadas preferencias hacia algunos tipos alimentarios. El índice de Morisita-Horn indicó que existe un traslape alto entre las dietas por sexo (hembras y machos o = 0.78), temporadas (cálida y fría o = 0.95) y entre tallas (chica y mediana o = 0.94, chica y grande o = 0.74, mediana y grande o = 0.83).

Environmental influences on the spatial and temporal distribution of the puffer fish Sphoeroides greeleyi and Sphoeroides testudineus in a Brazilian subtropical estuary

The spatial and temporal distribution of Sphoeroides greeleyi and Sphoeroides testudineus were established from collections (biological material and environmental data) conducted on a monthly basis from May 2000 to April 2001 in intertidal areas along the north-south axis of the estuarine complex of Paranaguá, Paraná State. In addition to characterizing a north-south spatial gradient, which fluctuates seasonally, the variation in the abiotic factors made possible the division of the estuary into three regions: north, central and south. Spatially, it was found that the number of individuals declines significantly for both species in the north-south direction of the estuary. Moreover, significant differences were found in the size of individuals across the estuarine regions. The largest S. greeleyi individuals were caught in the north, as well as the smallest S. testudineus individuals. The catches with the highest numbers of puffer fish occurred from late spring to early autumn, coinciding with the occurrence of specimens of smaller size and lower mean body mass. The results indicate that spatial and temporal variations in the environment impact the distribution patterns of both puffer fish species, suggesting that the co-occurrence of closely related species functions as a modulating factor in that distribution.

A distribuição espacial e temporal de Sphoeroides greeleyi e Sphoeroides testudineus foram estabelecidas a partir de coletas (material biológico e dados ambientais) realizadas mensalmente de maio/2000 a abril/2001 em áreas intertidais, no eixo norte-sul, do complexo estuarino de Paranaguá, Estado do Paraná. A variação dos fatores abióticos coletados, além de caracterizar um gradiente espacial, no sentido norte-sul, que varia sazonalmente, possibilitou a divisão do estuário em três regiões: norte, central e sul. Espacialmente, verificou-se para ambas as espécies que o número de indivíduos decresce, significativamente, no sentido norte-sul estuarino. Ainda, foram encontradas diferenças significativas no porte dos indivíduos entre as regiões do estuário, no norte ocorreram os maiores indivíduos de S. greeleyi e os menores de S. testudineus. As maiores capturas dos baiacus ocorreram do final da primavera ao início do outono, coincidindo com a ocorrência de exemplares de menor tamanho e de menor massa corporal média. Os resultados indicam que as variações espaciais e temporais do ambiente afetam os padrões de distribuição de ambas as espécies de baiacus, sugerindo que a co-ocorrência de espécies aparentadas age como um fator modulador nesta distribuição.