First island species of Hyalella (Amphipoda, Hyalellidae) from Florianpolis, state of Santa Catarina, Southern Brazil.

The Hyalella comprises a group of freshwater amphipods endemic to the Americas. In Brazil, the greatest diversity of species known so far is concentrated in the state of Rio Grande do Sul, but recently discoveries were made in the neighboring state of Santa Catarina. The present work describes the first island species of the genus Hyalella in Brazil and the fifth with occurrence in the state of Santa Catarina. The species was found in streams of two watersheds, located at the Monumento Natural Municipal da Lagoa do Peri, an important environmental protection area on the island of Florianpolis, Southern Brazil. Hyalella insulae n. sp. shows the following characters: inner face of propodus of gnathopod 1 with 7 serrate setae, gnathopod 2 with propodus ovate, peduncle of uropod 3 with 10 cuspidate setae, telson rectangular, wider than long, with 6 cuspidate setae and 2 plumose setae laterally close to each distal seta. H. insulae n. sp. differs from the other species with occurrence in Santa Catarina, H. catarinensis, H. rioantensis, H. sambaqui and H. lagoana, mostly concerning to the number and shape of setae of the gnathopods, uropods and telson. A comparison was also made with species from the neighboring states, Rio Grande do Sul and Paran. The description of H. insulae n. sp. in the present study contributes to increasing the knowledge of the Hyalella diversity in the state of Santa Catarina, little known so far.

A new species of freshwater amphipod (Crustacea, Peracarida, Hyalellidae) from Southern Brazil.

The freshwater amphipod of the genus Hyalella is typical from continental American waters and shows high levels of endemicity and Brazil has the second largest diversity. A new species is described here, Hyalella longipropodus n. sp. that occurs in a spring of southern Brazil in the municipality of Palmeira das Misses, in the northwestern region of state of Rio Grande do Sul, southern Brasil. Hyalella longipropodus n. sp. shows the following character states: antenna 2 more than half body length, gnathopod 2 propodus elongated, uropod 1 inner ramus of male without apical curved setae, uropod 3 peduncle with seven strong distal setae with accessory setae, ramus of uropod 3 with ten cuspidate setae with accessory setae. Hyalella longipropodus n. sp. occurs in sympatry with H. gauchensis, but these differ especially in the size and shape of gnathopod 2, the presence of curved setae on uropod 1 in H. gauchensis and the absence in H. longipropodus n. sp., antenna length (longer in H. longipropodus n. sp.) and number of cuspidate setae on uropods 1, 2, and 3. Besides the morphological differences, H. longipropodus n. sp. presented genetic differences always above 19% for the COI gene and 29 % for the 16S rRNA gene, when compared with other species found in the northwestern region of the state of Rio Grande do Sul, showing that it is really a species not yet described by science.

Induction of ovarian growth in Aegla platensis (Crustacea, Aeglidae) by means of neuroregulators incorporated to food

The freshwater crab Aegla platensis was used as a model to induce ovarian growth by adding different neuroregulators to a pellet food formulation. Added compounds were the dopaminergic inhibitor spiperone or the enkephalinergic inhibitor naloxone, both of them at a dose of 10-8 mol/animal. Animals were fed on the enriched pellets twice a week. After 7 wk, the gonadosomatic index (GI) was calculated as (gonad fresh weight / body fresh weight) x 100. GI significantly increased only for those females fed on spiperone pellets, compared to a control group receiving pellets with no compound added. During the assayed period, spiperone would be reverting the arrest exerted by dopamine on the neuroendocrine stimulation of ovarian growth. On the other hand, for both spiperone and naloxone a higher GI was correlated to a higher lipid content of both gonads and/or hepatopancreas, suggesting an increased energetic demand in accordance with an active investment in reproduction. Rev. Biol. Trop. 56 (3): 1201-1207. Epub 2008 September 30.

Se utilizó al anomuro de agua dulce Aegla platensis como modelo para inducir el crecimiento ovárico mediante el agregado de diferentes neuroreguladores a una formulación de alimento pelleteado. Los compuestos agregados fueron el inhibidor dopaminergico spiperona ó el inhibidor encefalinérgico naloxone, ambos a una dosis de 10-8 moles/animal. Los animales fueron alimentados dos veces a la semana con pellets enriquecidos con alguno de los neuroreguladores. Luego de 7 semanas, se calculó el índice gonadomático (IG) como (peso gonadal fresco/ peso corporal fresco) x 100. El IG mostró un incremento significativamente sólo en aquellas hembras alimentadas con pellets enriquecidos con spiperona, en comparación con un grupo control que recibió pellets sin agregado alguno. Durante el período ensayado, la spiperona estaría revirtiendo el arresto ejercido por la dopamina sobre la estimulación neuroendocrina del crecimiento ovárico. Por otro lado, para ambos grupos experimentales (spiperona y naloxone), un mayor valor de IG estuvo correlacionado a un mayor incremento del contenido de lípidos tanto en gonadas como en hepatopáncreas, sugiriendo una demanda energética incrementada en relación con una activa inversión en reproducción.