Maternal investment in egg production: environmental and population-specific effects on offspring performance in the snapping shrimp Alpheus nuttingi (Schmitt, 1924) (Decapoda, Alpheidae)

Among marine invertebrates, the overall biomass invested in egg production varies widely within populations, which can result from the interaction of endogenous and exogenous factors. Species that have constant reproduction throughout the year can be good models to study the influence of environmental factors on reproductive processes. We conducted a seasonal comparison of egg production in the intertidal snapping shrimp Alpheus nuttingi, which shows a continuous reproductive pattern, to examine the hypothesis that differences in egg production are driven by environmental conditions and population features. This population showed an uncommon strategy, characterized by females that produce eggs of varying sizes within their clutches, with reduced egg volume when the number of eggs is higher (Spring-Summer). In these seasons, higher temperatures and greater food availability may allow the production of more eggs compared to the Autumn-Winter seasons. Compared to other alpheid shrimps, this population produces small eggs, but in larger numbers. Despite the higher fecundity, the reproductive output is relatively low, this production being supported by the large size of females from the southern Atlantic region. Our findings showed that the egg production of A. nuttingi was greatly influenced by environmental factors. Therefore, this shrimp, and probably other decapods that possess continuous reproduction, adopt different reproductive strategies during the year. (C) Koninklijke Brill NV, Leiden, 2010.

Temporal dynamic of the relationship between the parasitic isopod Aporobopyrus curtatus (Crustacea: Isopoda: Bopyridae) and the anomuran crab Petrolisthes armatus (Crustacea: Decapoda: Porcellanidae) in southern Brazil

The prevalence of the parasite Aporobopyrus curtatus in Petrolisthes armatus from southern Brazil was determined, and the effect the parasite had on host reproduction was evaluated. Of all 775 crabs sampled in Araca region from March 2005 to July 2006, 3.2% presented bopyrid parasites. All the parasitized individuals had one branchial chamber occupied by two mature parasites, with no preference for the right or left chamber. Male and female hosts were infested in equal proportions. Parasitized juveniles, large individuals and ovigerous females were not found in our study. The absence of parasitized ovigerous females seems to be insufficient evidence to support the hypothesis of parasitic castration and would require a histological study to confirm their reproductive death. The percentage of infestation observed in our study (3.1%) is lower than the one found in other studies and it could indicate the existence of factor(s) regulating the density of A. curtatus in the Araca region. At least in this population, the low but constant presence of the bopyrid A. curtatus population did not appear to have a negative effect on the porcellanid population, and parasitized individuals did not play a significant role in the natural history of P. armatus.

Cranial anatomy of a new genus of hyperodapedontine rhynchosaur (Diapsida, Archosauromorpha) from the Upper Triassic of southern Brazil

Detailed description of the cranial anatomy of the rhynchosaur previously known as Scaphonyx sulcognathus allows its assignment to a new genus Teyumbaita. Two nearly complete skulls and a partial skull have been referred to the taxon, all of which come from the lower part of the Caturrita Formation, Upper Triassic of Rio Grande do Sul, southern Brazil. Cranial autapomorphies of Teyumbaita sulcognathus include anterior margin of nasal concave at midline, prefrontal separated from the ascending process of the maxilla, palatal ramus of pterygoid expanded laterally within palatines, dorsal surface of exoccipital markedly depressed, a single tooth lingually displaced from the main medial tooth-bearing area of the maxilla, and a number of other characters (such as skull broader than long; a protruding orbital anterior margin; anguli oils extending to anterior ramus of the jugal; bar between the orbit and the lower temporal fenestra wider than 0.4 of the total orbital opening; mandibular depth reaching more than 25% of the total length) support its inclusion in Hyperodapedontinae. T. sulcognathus is the only potential Norian rhynchosaur, suggesting that the group survived the end-Carnian extinction event.

Estimating population features of the anomuran crab Petrolisthes armatus (Porcellanidae) in a remaining and impacted mangrove area of the western Atlantic

This study evaluated biological aspects of Petrolisthes armatus inhabiting a remaining but disturbed mangrove area of Brazil. Samples were taken from March 2005 to July 2006, during low tide in the rocky-shore region. The size frequency distribution for all the individuals collected was bimodal. The sex ratio obtained was not different from 1: 1, and the population was classified as standard. A higher reproductive ratio and earlier ovigerous conditions were found in relation to another southern population; these can be hypothesized as adaptations to life in a stressed environment. Even though the population living in Ara has been subject to an environment frequently disturbed by human-produced pollutants, our results show no sign of negative effects on reproductive stages, recruits or members of the population in general. The population profiles of P. armatus show some peculiarities when compared to other populations inhabiting non disturbed environments.

Does Petrolisthes armatus (Anomura, Porcellanidae) form a Species Complex or Are We Dealing with Just One Widely Distributed Species?

Fernando L. Mantelatto, Leonardo G. Pileggi, Ivana Miranda, and Ingo S. Wehrtmann (2011) Does Petrolisthes armatus (Anomura, Porcellanidae) form a species complex or are we dealing with just one widely distributed species? Zoological Studies 50(3): 372-384. Petrolisthes armatus has the widest distribution known among members of the family Porcellanidae and is one of the most ubiquitous and locally abundant intertidal decapods along the Atlantic coast of the Americas. Considering its geographical distribution and morphological plasticity, several authors postulated the existence of a P. armatus species complex. In the present study we used genetic data from the mitochondrial 16S ribosomal gene to determine the genetic variability of P. armatus from selected locations within its eastern tropical Pacific and western Atlantic distributions. Our phylogenic analysis included 49 specimens represented by 26 species of the genus Petrolisthes and 16 specimens from 10 species and 4 related genera. Genetic distances estimated among the analyzed Petrolisthes species ranged from 2.6%-22.0%; varied between 0%-5.7% for 16S. Additionally, the revision of P. armatus specimens from Pacific Costa Rica and Brazilian Waters showed no geographically significant morphological variations among the analyzed specimens. Therefore, our morphological and genetic data do not support the hypothesis of a P. armatus complex within the specimens studied herein from the Americas, but convincingly confirm the monophyly and non-separateness of the members assigned as P. armatus. http://zoolstud.sinica.edu.tw/Journals/50.3/372.pdf

Reproductive strategy of the snapping shrimp Alpheus armillatus H. Milne-Edwards, 1837 in the South Atlantic: fecundity, egg features, and reproductive output

The family Alpheidae, composed by shrimps of relatively small size, popularly known as snapping shrimps, is the one of the most diverse decapod groups. These shrimps are found worldwide and Occur in tropical and subtropical waters, from the intertidal zone to great depths. We investigated reproductive aspects of Alpheus armillatus, in order to gather information on egg production, aiming to enhance knowledge of its reproductive strategies in a population in an intertidal area of the South Atlantic. Ovigerous females were collected under rocks, in May and July 2006 (dry season) and in November 2006 and March 2007 (rainy season). Egg production and reproductive output were analyzed and compared seasonally and during the period of embryonic development. Females measured on average 11.28 mm CL with a mean of 763 eggs and 0.11 mm(3) egg volume. The egg volume of this population was smaller than previous estimates for other species of snapping shrimps, but the mean egg number was higher. The volume of eggs doubled during the incubation period, but despite this increase, no significant loss of eggs was observed. Alpheus armillatus invests oil average about 12% of body weight in reproduction. The proportional investment in egg production IS Significantly higher in the rainy season when compared with the dry season (17.9% vs 4.8%), correlated with higher temperatures and increased food availability at this time. Our results corroborated the hypothesis of a pattern of egg production influenced by environmental conditions and intraspecific variability among the family Alpheidae, as a function of the biogeographic region.

A comparative study of population traits between two South American populations of the striped-legged hermit crab Clibanarius vittatus

The striped-legged hermit Crab Clibanarius vittatus, with a geographical distribution covering a wide range Of latitudes in the western Atlantic, was selected for a comparative study on population features between two different areas of the Brazilian coast that are separated by approximately 3000 km. The two populations Were sampled concurrently for nine months. The populations in northern and southeastern Brazil showed different profiles in terms of size of specimens, sex ratio, and shell occupation. The observed plasticity of these life-cycle traits of C. vittatus in relation to local environmental conditions is discussed. (C) 2009 Elsevier Masson SAS. All rights reserved

Galectin-3 regulates peritoneal B1-cell differentiation into plasma cells

Extracellular galectin-3 participates in the control of B2 lymphocyte migration and adhesion and of their differentiation into plasma cells. Here, we analyzed the role of galectin-3 in B1-cell physiology and the balance between B1a and B1b lymphocytes in the peritoneal cavity. In galectin-3(-/-) mice, the total number of B1a lymphocytes was lower, while B1b lymphocyte number was higher as compared to wild-type mice. The differentiation of B1a cells into plasma cells was associated with their abnormal adhesion and location on the mesentery. The B220 and CD43, constitutively expressed by B1 lymphocytes, were respectively up- and downregulated in galectin-3(-/-) mice. Mononuclear cells were strongly adhered to the mesenteric membranes of both CD43(-/-) and galectin-3(-/-) mice, but in contrast to CD43(-/-) mice, the accumulation of B1 cells in peritoneal membranes in galectin-3(-/-) mice was accompanied by their functional differentiation into plasma cells. We have shown that in the absence of galectin-3, B1-cell differentiation into plasma cells is favored and the dynamic equilibrium of B1-cell populations in the peritoneum is maintained through a compensatory increase in B1b lymphocytes.