Abstract Alpheus christofferseni Anker, Hurt and Knowlton, 2007 was described based on four specimens from Atol das Rocas, northeastern Brazil, and one specimen from Bocas del Toro, the Caribbean coast of Panama. Here, we report the collection of two specimens from Pernambuco, Brazil (~ 8°41’S), thus increasing the knowledge on species distribution along the Brazilian coast by approximately five latitudinal degrees south of its type locality (Atol das Rocas, Rio Grande do Norte, ~ 3°51'S). We also report a substantial increase in the known bathymetric distribution from shallow intertidal to approximately 51 m. Notes on morphological variation are provided based on the new material, and the first sequence of the 16S ribosomal subunit gene for the Brazilian coast is provided and compared with congeners.

Abstract Marine shrimps of the genus Thor Kingsley, 1878 are distributed in the eastern and western Atlantic, eastern Pacific, and Indo-West Pacific. Thor manningi Chace, 1972 was originally described from Antigua and since then has been recorded from other Atlantic localities, including the Caribbean Sea, Bermuda, USA, Brazil, and Ascension Island. Specimens previously identified as T. manningi from Panama and Brazil were analyzed using a combination of morphological and molecular approaches. The analyses yielded a new species from the Atlantic coast of Panama, herein described as Thor paulae sp. nov. Moreover, we provide additional morphological observations on T. manningi, mainly regarding mouthparts and pereopods. The new species is morphologically similar to the Pacific Thor cocoensis Wicksten and Vargas, 2001 and Thor marguitae Bruce, 1978. However, it can be separated from them by the carpus of the second pereopod, rostral dorsal dentition, and chela of the first pereopod, respectively. The two species studied here can be easily distinguished by the supraorbital prominence in T. manningi (versus absent in the new species), and the pterygostomial margin rounded and unarmed in T. manningi (versus angular, with tooth in the new species). Thor manningi is morphologically closer to the western Atlantic Thor dobkini Chace, 1972 and Thor floridanus Kingsley, 1878, but can be separated from both by the merus of the first pereopod (T. dobkini) and dactylus of fourth and fifth pereopods (T. floridanus, but with the possibility of overlap). We provide a comparative table with morphological characters of all 17 valid species of Thor, as well as a worldwide identification key to the genus.

Abstract We designed 14 new primers for amplification of the COI barcode region of decapod crustacean species. We tested, with high level of success, the generation of ~ 640 ± 49 base-pair sequences in selected groups of decapods (hermit crabs, squat lobsters, marine and freshwater crabs and shrimps), encompassing representatives of 27 genera of 15 families, 11 of Pleocyemata (Anomura, Brachyura, and Caridea) and 4 of Dendrobranchiata. Based on the results we expect the applicability of these primers for several studies with different taxa within Decapoda.

This study aimed to assess the spatial and seasonal distribution of the hermit crab Pagurus exilis in Caraguatatuba region, characterizing the abundance and distribution of individuals seasonally and bathymetrically. The relationship between groups of individuals and environmental factors (temperature, salinity, depth, amount of organic matter and texture of sediment) was checked. Sampling was carried out monthly from July 2001 to June 2003, at seven depths (5, 10, 15, 20, 25, 30 and 35 m), with a shrimp fishery boat equipped with two double-rigged trawling nets. A total of 1960 specimens of P. exilis were collected, including 1369 (69.9%) males, 304 (15.5%) non-ovigerous females and 287 (14.6%) ovigerous females. The individuals were distributed between 15 and 35 m and were absent at 5 m. A large amount of individuals was collected (40.6%) during winter and 57.8% of ovigerous females were also captured in the same period. Pagurus exilis tended to occur in association with a group of factors composed by: higher depths (15 to 35 m), higher salinity (34 to 37 psu), lower temperature (18 to 24ºC), and sediment of organic matter varying from 1 to 9%.

Este estudio tuvo por objetivo determinar la distribución espacial y temporal del cangrejo ermitaño Pagurus exilis en la región de Caraguatatuba, caracterizando la abundancia y distribución en función de la estación del año y profundidad. Se determinaron las relaciones entre los individuos y algunos factores abióticos (temperatura, salinidad, profundidad, concentración de materia orgánica y textura del sedimento). Las capturas fueron realizadas mensualmente, entre julio de 2001 y junio de 2003, en siete profundidades (5, 10, 15, 20, 25, 30 y 35 m), utilizando dos redes de arrastres. Se obtuvo un total de 1960 individuos de P. exilis, incluyendo 1369 (69,9%) machos, 304 (15,5%) hembras no ovígeras y 287 (14,6%) hembras ovígeras. Los animales estuvieron distribuidos entre 15 y 35 m de profundidad y ausentes en 5 m. La mayor cantidad de individuos (40,6%) fue obtenida durante el invierno y así como 57,8% de las hembras ovígeras. La presencia de Pagurus exilis parece estar relacionada con la combinación de algunos factores abioticos tales como profundidad (15 y 35 m), alta salinidad (34 a 37 psu), temperatura baja (18 a 24ºC), y concentración de materia orgánica entre 1 y 9%.