Dinâmica populacional do caranguejo Austinixa aidae (Brachyura, Pinnotheridae): simbionte de Callichirus major (Thalassinidea, Callianassidae) no Atlântico sudoeste

The Pinnotheridae family is one of the most diverse and complex groups of brachyuran crabs, many of them symbionts of a wide variety of invertebrates. The present study describes the population dynamics of the pea crab Austinixa aidae (Righi, 1967), a symbiont associated with the burrows of the ghost shrimp Callichirus major (Say, 1818). Individuals (n = 588) were collected bimonthly from May, 2005 to September, 2006 along a sandy beach in the southwestern Atlantic, state of São Paulo, Brazil. Our data indicated that the population demography of A. aidae was characterized by a bimodal size-frequency distribution (between 2.0 and 4.0 mm and between 8.0 and 9.0 mm CW) that remained similar throughout the study period. Sex ratio does not differ significantly from 1:1 (p > 0.05), which confirms the pattern observed in other symbiontic pinnotherids. Density values (1.72 ± 1.34 ind. • ap.-1) are in agreement with those found for other species of the genus. The mean symbiosis incidence (75.6%) was one of the highest among species of the Pinnotheridae family, but it was the lowest among the three studied species of the genus. Recruitment pattern was annual, beginning in May and peaking in July, in both years, after the peak of ovigerous females in the population (from March to May). Our findings describe ecological and biological aspects of A. aidae similar to those of other species of this genus, even from different geographic localities.Pinnotheridae constitui um dos mais diversos e complexos grupos de caranguejos, sendo muitos deles simbiontes de uma grande variedade de invertebrados. O presente estudo descreve a dinâmica populacional do caranguejo pinoterídeo Austinixa aidae (Righi, 1967), um simbionte que vive associado às galerias do "corrupto" Callichirus major (Say, 1818). Os exemplares (n = 588) foram coletados a cada dois meses entre maio de 2005 e setembro de 2006, em uma praia arenosa no litoral de São Paulo, Brasil. Nossos resultados indicaram que a população de A. aidae foi caracterizada por uma distribuição bimodal em classes de tamanho (entre 2,0 e 4,0 mm (CC: comprimento da carapaça) e entre 8,0 e 9,0 mm (CC)), padrão constante ao longo do período de estudo. A razão sexual não diferiu significativamente de 1:1 (p > 0,05), confirmando o padrão observado para outros pinoterídeos simbiontes. Os valores de densidade desta espécie (1,72 ± 1,34 indivíduos por toca) estão de acordo com os estabelecidos para o gênero. A incidência média (75,6%) está entre as mais altas das espécies de Pinnotheridae, entretanto é a menor dentre as três espécies do gênero já estudadas. O padrão de recrutamento foi anual (tendo início em maio e atingindo maior proporção em julho, nos dois anos de estudo), e foi registrado após os picos de ocorrência de fêmeas ovígeras na população (de março a maio). Nossos resultados confirmam que A. aidae possui padrões ecológicos e biológicos similares aos desenvolvidos pelas espécies do gênero, mesmo em diferentes localidades

The reproductive performance of the Red-Algae shrimp Leander paulensis (Ortmann, 1897) (Decapoda, Palaemonidae) and the effect of post-spawning female weight gain on weight-dependent parameters

Decapod species have evolved with a variety of reproductive strategies. In this study reproductive features of the palaemonid shrimp Leander paulensiswere investigated. Individuals were collected in the coastal region of Ubatuba, São Paulo, Brazil. In all, 46 ovigerous females were examined in terms of the following reproductive traits: fecundity, reproductive output, brood loss and egg volume. Leander paulensis produces a large number of small eggs with an average fecundity of 635 ± 246 eggs. Egg volume increased significantly from early (0.034 ± 0.008 mm3) to late development stage (0.05 ± 0.012 mm3). The reproductive output did not correlate with female size. The weight of females bearing stage 2 eggs was significantly higher than that of females carrying stage 1 eggs. We assume that the reason for this weight gain is the recovery of female reserves that have been depleted for egg production. Moreover, we emphasize that this weight gain must be considered when evaluating weight-dependent variables such as reproductive output or brood loss in relation to female weight. Otherwise, an overestimation of these variables might lead to inaccurate results.Decápodes desenvolveram uma ampla variedade de estratégias reprodutivas. Neste estudo foram investigadas características reprodutivas da espécie de PalaemonidaeLeander paulensis. Os indivíduos foram coletados na região costeira de Ubatuba, São Paulo, Brasil. Foram examinadas 46 fêmeas ovígeras quanto aos seguintes aspectos reprodutivos: fecundidade, investimento reprodutivo, perda de ovos e volume dos ovos. Leander paulensis produz uma grande quantidade de pequenos ovos, com fecundidade média de 635 ± 246 ovos. O volume dos ovos aumentou significativamente quando comparado o estágio inicial (0.034 ± 0.008 mm3) com o estágio final de desenvolvimento (0.05 ± correlação com o tamanho das fêmeas. Fêmeas com ovos no estágio 2 apresentaram massa corpórea seca significativamente maior que aquelas carregando ovos no estágio inicial. Esse aumento de massa parece ser decorrente da recuperação de reservas energéticas das fêmeas, que teriam sido utilizadas durante a produção de ovos. Além disso, deve-se considerar neste tipo de avaliação o aumento da massa corpórea em relação ao investimento reprodutivo, assim como da perda de ovos relacionada à massa das fêmeas ou qualquer outra variável dependente do peso

Shell Utilization Pattern by the Hermit Crab Isocheles sawayai Forest and Saint Laurent, 1968 (Anomura, Diogenidae) from Margarita Island, Caribbean Sea, Venezuela

Isocheles sawayai is a hermit crab that is occasionally mentioned in the literature, and recently its distribution was extended to Venezuelan waters. Because no information on the biology and shell use patterns of this species inhabiting Caribbean waters is available, we provide the first information on shell occupation patterns of I. sawayai from Venezuela. Specimens were collected monthly from January to December 2000 along the sandy shore of Margarita Island, Venezuela. The 942 specimens collected showed different shell use patterns between the sexes and according to the reproductive condition of the females. The gastropods Leucozonia nassa (37.37%), Engoniophos unicinctus (25.37%), Nassarius vibex (4.88%), Melongena melongena (4.25%), and Stramonita haemastoma (3.82%) represent 76% of the total occupied shells. Of the total of 26 different shell species occupied by I. sawayai, males were found occupying 21, while females were found occupying all 26 shell species. In general, both sexes most frequently occupied L. nassa and E. unicinctus. However, the percentage of females occupying these shells was significantly higher than that of the males. Regression analyses showed the best correlation between crab size, shell aperture width, and shell internal volume. The current comparative investigation, in combination with other South Atlantic populations of I. sawayai, provided further evidence of shell use adaptation in hermit crabs from different areas, and increases our insight into shell use of shallow-water hermit crabs

Spermatophore and Gonopore Morphology of the Southwestern-Atlantic Hermit Crab Pagurus exilis (Benedict, 1892) (Anomura, Paguridae)

Marcelo A. Scelzo, Marina Z. Fantucci, and Fernando L. Mantelatto (2010) Spermatophore and gonopore morphology of the southwestern-Atlantic hermit crab Pagurus exilis (Benedict, 1892) (Anomura, Paguridae). Zoological Studies 49(3): 421-433. The form and function of the spermatophore have been used as a complementary tool in studies of the reproductive biology and systematics of hermit crabs. In this context, we describe the spermatophore and gonopore morphology of Pagurus exilis. The spermatophores were extracted from the distal part of the vas deferens of specimens collected in Argentina and Brazil. The spermatophores were composed of 3 major regions: a main ampulla (with a sperm capsule inside and an accessory ampulla at the base), a stalk, and a pedestal. Each spermatophore had a distinct dorsolateral suture line around the ampulla, where the rupture occurs to release the sperm. The spermatophore total length was 1.5 times the main ampulla length. The main ampulla was oval and slightly flattened. A triangular accessory ampulla extended from the main ampulla base to the pedestal on 1 side, and contained no to several sperm. The stalk is short and flattened, and as wide as the main ampulla. One to 3 spermatophores were found attached to each pedestal, which was almost oblong in shape. The dimensions of the spermatophore and its component parts were directly influenced by the size of the hermit crab. Gonopores of males were covered by long pappose setae, while female gonopores bore a few short cuspidate setae. Specimens from Brazil and Argentina had the same spermatophore morphology, corroborating the previously observed absence of genetic differences between the both populations. The spermatophore morphology of this species has similarities with the broad general pattern of the Paguridae, being most similar to one of the (at least) 3 patterns of spermatophore morphology described for Pa gurus. http://zoolstud.sinica.edu.tw/Journals/49.3/421.pdfPIP CONICET[5135/06]Universidad Nacional de Mar del Plata[EXA 357/06]Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq, Brasilia, Brazil)[490340/2004-0]Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq, Brasilia, Brazil)[490122/2006-0]CAPES (Brasilia, Brazil)Universidade de São Paulo - FFCLRP/USPUniversidade de São Paulo - Centro de Biologie Marinha (CEBIMar/USP, Sao Sebastiao, Brazil

A multigene and morphological analysis expands the diversity of the seabod shrimp Xiphopenaeus Smith, 1869 (Decapoda: Penaeidae), with descriptions of two new species

After being stable for nearly a century, the taxonomic history of the genus Xiphopenaeus has been marked by many changes in the last three decades. The taxonomic status of the Atlantic species has a low resolution, and many species are still undefned and grouped as cryptic species. Here we employed an integrative approach to defne the species of Xiphopenaeus and the morphological characters needed to diferentiate them. We combined the analyses of two molecular markers (COI and 16S rDNA), scanning electron microscopy and light microscopy. Based on specimens from 17 localities from the Atlantic and Pacifc oceans, we detected fve divergent genetic groups, three in the Atlantic (A1, A2, A3) and two in the Pacifc (P1, P2). Male secondary sexual characters were able to diferentiate four out of the fve genetic groups. Group A1 corresponds to X. kroyeri, and A2 and A3 correspond to new species. We redescribed the genus and two new species are described and illustrated: Xiphopenaeus dincao nov. sp. (A2) and Xiphopenaeus baueri nov. sp. (A3). Since the holotype of X. riveti was missing and the specimen analysed from group P2 was a female, the status of the species of Xiphopenaeus from the Pacifc remains unresolved

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.pdfCNPq-Brazil[Proc. 491490/2004-6]CNPq-Brazil[490353/2007-0]CONICIT-Costa Rica[CII-001-08]Univ. de Costa Rica[808-A8-209]CNPq[PQ 301261/04-0]CNPq[301359/07-5]CNPq[140677/08-9]FAPESP[2010/15588-8]FAPESP[05/50651-1]CAPES-Sandwich[1467/09-3]CAPES[02630/09-5]Universidade de São Paulo - FFCLRP/USPUniversidade de São Paulo - Centro de Biologia Marinha (CEBIMar/USP

Phylogeny, phylogeography, and systematics of the American pea crab genus Calyptraeotheres Campos, 1990, inferred from molecular markers

We used mitochondrial cytochrome oxidase I (COI) and the large ribosomal subunit (16S) genes to establish evolutionary relationships amongst species of Calyptraeotheres, evaluate their usefulness as DNA-barcoding genes, and assess molecular diversity at the population level within Calyptraeotheres garthi. Bayesian, maximum likelihood, and maximum parsimony phylogenies confirmed the monophyly of Calyptraeotheres, showing that the ancestor of C. garthi, Calyptraeotheres hernandezi, and Calyptraeotheres granti radiated after the formation of the Panamanian isthmus. This finding contradicts the austral/tropical hypothesis previously proposed based on morphological data. The COI and 16S distance matrices supported separation of species as well as the genera, and corroborated that DNA barcoding is a useful tool and complements the classical taxonomy in Pinnotheridae. Phylogenetic and genetic distance analyses suggested that C. hernandezi is a junior synonym of C. garthi. Finally, C. garthi did not show a population structure across its distribution range, and showed a pattern consistent with a recent population expansion event that began 230–300 Kya.Fil: Ocampo, Emiliano Hernan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Robles, Rafael. Universidade de Sao Paulo; BrasilFil: Terossi, Mariana. Universidade de Sao Paulo; BrasilFil: Nuñez, Jesus Dario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Cledón, Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Mantelatto, Fernando L.. Universidade de Sao Paulo; Brasi

New records and extension of the known distribution of some freshwater shrimps in Brazil

Freshwater prawns are distributed in rivers and streams of inland and brackish waters throughout America. In Brazilian waters are registered 35 species into 4 families (Atyidae, Euryrhynchidae, Palaemonidae, and Sergestidae). Information about the geographic distribution of this fauna is scattered in the literature and frequently not founded on documented data in scientific collections. Here we examined a series of specimens and detected several new records and extension of the known distribution of some freshwater shrimps in Brazil

Diversidad de especies y distribución de cangrejos de agua dulce (decapoda: Pseudothelphusidae) de la cuenca del río grande de térraba, vertiente pacífica de Costa Rica

During the last decades, knowledge on biodiversity of freshwater decapods has increased considerably; however, information about ecology of these crustaceans is scarce. Currently, the freshwater decapod fauna of Costa Rica is comprised by representatives of three families (Caridea: Palaemonidae and Atyidae; Brachyura: Pseudothelphusidae). The present study aims to describe the species diversity and distribution of freshwater crabs inhabiting the basin of the Rio Grande de Térraba, Pacific slope of Costa Rica, where the Instituto Costarricense de Electricidad (ICE) plans to implement one of the largest damming projects in the region. Samples were collected in 39 locations at an altitude ranging from 20 to 1,225 m. Sampling was carried out during several months in 2007, 2009 and 2010. We collected a total of 661 crabs, comprising eight species of Pseudothelphusidae of three genera, representing 53% of the 15 pseudothelphusid crab species currently recorded from Costa Rica. The most common species was Ptychophallus paraxanthusi followed by P. tristani. Freshwater crabs were more frequently encountered in the middle-low region of the basin (between 311 and 600 m) and less frequently in the medium-high basin (between 601 and 1,225 m). Ptychophallus paraxanthusi showed the widest distribution and was collected in altitudes ranging from 20 to 700 m. The Rio Grande de Térraba region can be considered as a relatively small, but highly diverse system. Therefore, any alteration of the basin of Rio Grande de Térraba, and especially the possible construction of a hydroelectric power plant, needs to be carefully analyzed to mitigate the damaging effects of this project on the freshwater crabs. More ecological information about freshwater crabs from Costa Rica and the Central American region are needed to reach a first reasonable overview on the ecological role of these decapods in freshwater systems

Population features of the western Atlantic hermit crab Pagurus exilis (Anomura, Paguridae) in Brazil

The population structure of the hermit crab Pagurus exilis has been studied in Caraguatatuba region (23o 34’ and 23o 51’S; 45o 10’ and 45o 26’W), northern coast of São Paulo, Brazil for the first time in terms of total and seasonal size frequency distribution, sex ratio and reproductive season. The animals were monthly collected during two consecutive years (2001/2003) with a fishery boat equipped with “double rig” nets. At the laboratory, the specimens were identified, counted, weighed and measured. A total of 1,963 animals were captured, which 1,372 were males and 591 females (311 non ovigerous females and 280 ovigerous ones). The size of animal (Cephalothoracic Shield Length) ranged from 2.4 to 8.3 mm, and males were significantly larger, showing a sexual dimorphism. The size frequency distribution showed an unimodal pattern with non-normal distribution. The total sex ratio was significantly different from the expected, biased to males (1:0.43). Most ovigerous females presented eggs in initial developmental stage, with a few percentages in intermediary and final stages. The profile found an abundant population with a continuous reproduction (ovigerous females occurring along the year).Aspectos populacionais do ermitão do Atlântico oeste Pagurus exilis (Anomura, Paguridae) no Brasil A estrutura populacional do ermitão Pagurus exilis foi estudada, na região de Caraguatatuba (23o 34’ e 23o 51’S; 45o 10’ e 45o 26’O), litoral norte de São Paulo, Brasil, pela primeira vez quanto à distribuição de freqüência de tamanho total e sazonal, razão sexual e período reprodutivo. Os animais foram coletados mensalmente durante dois anos consecutivos (2001/2003) com um barco de pesca equipado com redes “double rig”. No laboratório, os espécimes foram identificados, contados, pesados e medidos. Um total de 1963 animais foi capturado, sendo 1372 machos e 591 fêmeas (311 fêmeas não ovígeras e 280 fêmeas ovígeras). O tamanho dos animais (comprimento do escudo cefalotorácico) variou de 2,4 a 8,3 mm, e os machos foram significativamente maiores, demonstrando um dimorfismo sexual. A distribuição de freqüência de tamanho demonstrou um padrão unimodal com distribuição não-normal. A razão sexual total foi significativamente diferente do esperado, em favor dos machos (1:0,43). A maioria das fêmeas ovígeras apresentou ovos no estágio inicial de desenvolvimento, com uma pequena porcentagem em estágios intermediário e final. O perfil encontrado apresenta uma população abundante com reprodução continua (fêmeas ovígeras ocorrendo ao longo do ano)