Rony Roberto Ramos Vieira

JUVENILE DEVELOPMENT OF DILOCARCINUS PAGEI STIMPSON, 1861 (BRACHYURA, TRICHODACTYLIDAE) REARED IN THE LABORATORY, WITH EMPHASIS ON SETAE MORPHOLOGY

Univ Fed Rio Grande, Inst Oceanog, Lab Crustaceos Decapodos, BR-96201900 Rio Grande, RS, Brazil

Chave ilustrada para identificação das zoés de Brachyura do estuário da Lagoa dos Patos (RS) e região costeira adjacente

The goal of this study is to provide an illustrated identification key to distinguish zoeal phase of Brachyuran larvae that occur in the estuarine and nearby coastal region of the Patos Lagoon. The key includes species, collected monthly, using a conical net (165 cm long, 60 cm mouth and 330 µm mesh). Sampling was carried out on surface and deep waters. The identification was based on specimens reared under laboratory conditions as well as from previous published studies. This key was constructed upon external morphological characters, easy to observe under a stereomicroscope and moreover, the presentation of figures allows a non-specialist to make identifications more easily.

Fecundity of Palaemon carteri (Gordon, 1935) (Crustacea: Decapoda: Palaemonidae) from the Eastern Amazon, Brazil

Abstract Palaemon carteri is one of the most common palaemonid shrimps in the Amazon region. The objective was to analyze the fecundity of P. carteri from the Eastern Amazon. The specimens derive from 11 streams, which were sampled in 2011. Using a stereomicroscope and an ocular micrometer, the total length, cephalothorax length, rostrum length, and abdomen length of ovigerous females were obtained. The eggs were counted, and their major and minor axes were measured. Based on eye pigmentation in the eggs, two groups of females were sorted according to the development stage of the embryos. A total of 65 ovigerous females were analyzed, with mean total length of 26.11 ± 1.36 mm (range: 23.00 to 29.16). Regarding body size, there was no difference between the two groups of females. The mean egg number was 18 (range: 4 to 29). Females with eggs in the initial development stage had a higher number of eggs (mean: 20 ± 3.8) than the ones in a more advanced stage (mean: 16 ± 5.1). On the other hand, the latter presented a higher mean volume (0.91 ± 0.27 mm3). Palaemon carteri has low fecundity compared with other palaemonid species, and egg loss during incubation seems to favor the survival chances of the remaining embryos.

Abundance and distribution of Portunidae larval phases (Crustacea: Brachyura) in the estuarine and coastal region of the Patos Lagoon, southern Brazil

The abundance and distribution of larval phases of the Portunidae found in the estuary of the Patos Lagoon and the coastal region were studied during two years (1995 and 1999). A conical net (165 cm long, 60 cm mouth, and 330 µm mesh) equipped with a flowmeter was towed for three minutes at 2 knots at six stations within the estuary and four stations in the coastal region. Samplings were carried out on the surface and near the bottom. At each sampling location, the salinity and temperature were also recorded. In 1995, the zoeae of Arenaeus cribrarius (Lamarck, 1818), Callinectes sapidus Rathbun, 1896 and Achelous spinicarpus Stimpson, 1871 were caught, resulting in a total abundance of 121.98 ind.100 m-3 (90.95 ind.100 m-3 on the surface and 31.03 ind.100 m-3 near the bottom). A total of 452.27 ind.100 m-3 were caught in the megalopa phase (13.49 ind.100 m-3 on the surface and 438.78 ind.100 m-3 near the bottom). In 1999, only zoeae of C. sapidus were caught, resulting in a total abundance of 419.78 ind.100 m-3 (386.98 ind.100 m-3 on the surface and 32.8 ind.100 m-3 near the bottom). Megalopae of these three species were caught, resulting in a total abundance of 179.91 ind.100 m-3 (25.38 ind.100 m-3 on surface and 154.53 ind.100 m-3 near the bottom). Summer was the season with the highest abundance of larvae in both years. During spring and summer, spawning was observed in the estuarine region of the Patos Lagoon.

Range extension of the mud crab Eurypanopeus depressus (Smith, 1869) (Decapoda, Panopeidae): A new record for the coastal south of Brazil

The discovery of Eurypanopeus depressus (Decapoda: Panopeidae; Smith, 1869) on the coast of Rio Grande do Sul, Brazil suggests that the species was recently introduced, possibly due to different sources of introduction, such as the ballast water of ships. E. depressus were collected using otter-trawl net in the Patos Lagoon Estuary. Discussion focuses on the fact that the primary South American distribution derives from Uruguayan shores, and later expanded to nearby places (Brazil and Argentina). This work extends the Southern Hemisphere distribution for the species, as it was previously reported only from Argentina to Uruguay.

Morphology of the first zoeal stage of Macrobrachium surinamicum Holthuis, 1948 (Malacostraca, Decapoda, Palaemonidae) hatched in the laboratory

The first zoeal stage of the freshwater shrimp Macrobrachium surinamicum Holthuis, 1948 is described and illustrated based on hatchlings from an ovigerous female, collected in Rio Campupema, Abaetetuba, in the northern Brazilian state of Para, and compared with the first zoeae of several other species of the genus occurring in Brazil. Although the first zoeae of the different species of Macrobrachium are morphologically very similar, they can still be separated by a combination of morphological characters but only M. surinamicum has one smooth seta on the maxillular endopod. Although a complete larval series of M. surinamicum presently remains unknown, as pereiopods 3-5 and pleopods are absent, the outcome of this study suggests that the larval development of this species is extended and includes at least seven larval stages.

Desenvolvimento juvenil de Uca (Minuca) Burgersi holthuis, 1967 (Crustacea, Brachyura, Ocypodidae) em laboratório

The fiddler crab Uca (Minuca) burgersi has been recorded in eastern American coast, from Florida to Brazil (from Maranhao to Sao Paulo). The juvenile stages of U. burgersi are described here based on material reared under laboratory conditions. Additionally a comparison of juvenile morphology is given for the juvenile of other species already studied with occurrence in the Brazilian coast. Larvae of U. burgersi were obtained from one ovigerous female hatched in the laboratory, which reached until the tenth juvenile stage. Rearing was conducted in a temperature-controlled climatic chamber at 25±1oC, 34‰ salinity and 12/12 (L/D) photoperiod. The first juvenile crab appeared at 43 days after hatching. Only one individual reached the tenth stage 174 days after hatching. The morphology of first juvenile crab was described as well as morphological changes throughout juvenile development. The sexual definition occurs in the fourth juvenile stage, abdominal dimorphism occurs in the sixth juvenile stage and chelipeds dimorphism occurs in the seventh juvenile stage.