Murilo Zanetti Marochi

Sexual dimorphism in Aegla marginata (Decapoda: Anomura)

A study on sexual dimorphism in Aegla marginata was conducted using geometric morphometric methods. The carapace of 47 females and 75 males and the left and right cheliped propodus of 29 females and 40 males were analyzed. Eighteen landmarks were established in the carapace and 10 in the cheliped propodus. A Generalized Procrustes Analysis based on landmark configurations was used to separate the components of size and shape. A Student t-test was used to determine whether statistically significant sexual dimorphism was shown by the carapace and the cheliped propodus. The variation in the shape of the structures was evaluated with a discriminant analysis. Our results show that there is no sexual dimorphism in the carapace of A. marginata. However, the size of the propodus differed statistically between the sexes. The carapace shape differed between the sexes: the females showed a wider posterior area and a narrower anterior area than the males. The shape of the cheliped propodus also differed between the sexes: overall, the females had a longer and narrower cheliped propodus than the males. The variations in the carapace shape found in this study confirm the results of other studies on aeglid morphology; however, the information presented by this study regarding variation in the shape of the cheliped propodus is new to the literature. The geometric morphometric approach applied in this study provided useful tools for achieving the proposed objectives.

Sexual maturity and reproductive period of the swimming blue crab Callinectes danae Smith, 1869 (Brachyura: Portunidae) from Guaratuba Bay, Paraná State, southern Brazil

This work aims to estimate the average size at the onset of morphological and physiological sexual maturity and the reproductive period of Callinectes danae. Specimens were captured from a shrimp fishing boat equipped with a trawl net from March 2009 to February 2010. After sorting, crabs were sexed, and the following morphometric dimensions were measured: carapace width (CW), length and height of the major (MAP and HMAP), and the minor cheliped propodus (MIP and HMIP) for both sexes, and the abdominal width for females (AW). The onset of morphological maturity was estimated with the REGRANS program, in which the inflection point is calculated. The size at the onset of physiological maturity was determined by logistic regressions fitted to the relationships between the percentages of juvenile and adult individuals of each CW. A total of 893 individuals were sampled. Of these individuals, 389 were males, 472 non-ovigerous females, and 32 ovigerous females. The CW ranged from 19.81 to 117.17 mm for males, 19.91 to 113.11 mm for non-ovigerous females, and 70.55 to 88.60 mm for ovigerous females. Morphological sexual maturity was attained at 86.47 mm CW (males) and 67.87 mm CW (females). The size at the onset of physiological maturity was calculated to be 86.50 mm CW (males) and 67.00 mm CW (females). Due to the closeness of these values, both techniques were deemed suitable for determination of the onset of sexual maturity in C. danae. This species reproduces throughout the year, but reproduction is more intense during the winter. Mature males are present throughout the year. Data from this investigation will help resource managers to develop strategies that will ensure a sustainable harvest of this important species of swimming crab in southern Brazil.

Os caranguejos Eriphiidae, Menippidae, Panopeidae e Pilumnidae (Crustacea Brachyura) de águas rasas do litoral do Paraná, com chave pictórica de identificação para as espécies

A pictorial species identification key for crabs of the families Eriphiidae, Menippidae, Panopeidae and Pilumnidae from shallow waters of Parana State coast was elaborated. A description of the recognition characteristics and illustrations of the species are also presented. Crab samples were obtained from mangrove, estuary and oyster farming located in Guaratuba Bay and rocky shore in Matinhos city. Drawings and analyses were based on freshly collected specimens and on those deposited at Natural History Museum of Capao da Imbuia and at Laboratory of Ecology of Crustacea UFPR. A total of 13 species were analyzed, from which nine species of Panopeidae, two Pilumnidae and one of Eriphiidae and Menippidae. This species richness was considered similar to neighboring areas in spite of the short extension of the Parana State coast.

Genetic and Morphological Differentiation of the Semiterrestrial Crab Armases angustipes (Brachyura: Sesarmidae) along the Brazilian Coast

The genetic and morphometric population structures of the semiterrestrial crab Armases angustipes from along the Brazilian coast were examined. The influence of the Central South Equatorial Current on larval dispersal of A. angustipes also was evaluated. Six populations were sampled from estuarine areas in São Luis do Maranhão, Maranhão; Natal, Rio Grande do Norte; Maceió, Alagoas; Ilhéus, Bahia; Aracruz, Espírito Santo; and Guaratuba, Paraná. Patterns of genetic differentiation were assessed using DNA sequence data corresponding to parts of the mitochondrial cytochrome c oxidase subunit 1. Geometric morphometric techniques were used to evaluate morphological variation in shape and size of the carapace and right cheliped propodus. Our results revealed low genetic variability and lack of phylogeographic structure; geometric morphometrics showed statistically significant morphological differentiation and geographic structuring. Our data indicate the absence of possible barriers to gene flow for this mobile species, and no clear correlation of morphological or genetic variation with ocean currents and/or geographic distance. Our results also suggest that historical geological and climatological events and/or possible bottleneck effects influenced the current low genetic variability among the populations of A. angustipes.

Circadian rhythm in males of Aegla schmitti (Decapoda, Anomura, Aeglidae) under laboratory conditions

A study of the daily activity pattern of male Aegla schmitti was carried out in the laboratory. Animals were acclimated in aquaria with a water temperature of 18.5 °C and a photoperiod of 12:12 (day/night) for seven days. Two experiments were then performed. The first consisted of observing animals during the daytime when subjected to a natural photoperiod (NP); the second consisted of observing animals during the daytime hours but in the dark, whilst they were living under an inverted photoperiod (RP). The animals spent more time in active behaviors in the light and the time spent in these behaviors decreased during the night. By contrast, swimming and grooming showed peaks at 9:00 pm and midnight. This study is the first to evaluate the biology of behavioral aspects of A. schmitti, providing valuable information about feeding habits, mechanisms and patterns of agonistic activity in this crustacean family.

Morphological and genetic distinction of Armases angustipes and A. miersii (Decapoda, Brachyura, Sesarmidae)

Among coastal crabs of the family Sesarmidae from the western Atlantic, there have been problems of misidentification and controversial reports of distribution, especially due to the morphological similarity and sympatric occurrence of some species. In order to clarify the morphological distinction between Armases angustipes and Armases miersii we here summarize morphological information of the two species and provide new information on the distribution of A. angustipes . In addition, museum specimens from the Bahamas assigned to A. angustipes were morphologically and genetically re-identified as A. miersii , questioning the occurrence of the former species in this archipelago. In this case, there would be no geographic overlap between the two species, with A. angustipes becoming the southern form, mostly restricted to South America. Further studies on the variability among populations of A. miersii and A. angustipes are needed.

Asynchronous Hatching and Extended Parental Care in Aegla schmitti (Decapoda, Anomura)

The aim of this study was to describe the behavior of newly-hatched juveniles and maternal care in Aegla schmitti. The experiment was conducted using seven ovigerous females with eggs at different stages of embryonic development and 12 eggs that had been placed in a separate aquarium. We observed asynchronous hatching in all females, with a mean of 66 hatched juveniles per female. The females also exhibited extended maternal care, allowing the juveniles to remain inside their abdominal chamber or on other parts of their body in the first few days after hatching. The juveniles that hatched in a separate aquarium fed on the remaining eggs, despite food being available. The incubation period and number of hatched eggs are highly variable between species with direct development, with no clear pattern being evident. However, asynchrony in hatching time is apparently common among freshwater anomurans, most likely due to the environmental conditions in which they live. Parental care is an important trait for crustaceans that live in osmotically unfavorable environments, such as freshwater, increasing the survival rate of juveniles.

Ontogenetic shape changes and sexual dimorphism in Aegla marginata Bond-Buckup and Buckup, 1994

A study on relative growth, sexual dimorphism and ontogenetic trajectory was carried out in a population of the aeglidAegla marginata coming from Barrinha River, Iguape River Basin, Tunas do Paraná, Paraná State, Brazil. The size the of morphological sexual maturity was estimated for males and females. The analysis of sexual dimorphism and ontogenetic trajectory were performed using geometric morphometric technique. Males reach maturity with 10.58 mm of carapace length (CL) and females with 10.38 mm CL. Sexual size dimorphism was only visible among adults, with males reaching larger sizes. This is probably related to the reproductive strategy of males. However, sexual shape dimorphism was found for both juveniles and adults: the posterior region of the carapace was wider in females. As the contrast of this feature was stronger in adults, it can be considered that large abdomen is advantageous for egg incubation. The allometric trajectories of juveniles presented similar directions, becoming divergent during the adult phase. The shape variation inA. marginataoccurred gradually throughout its development, with no abrupt transformation upon reaching sexual maturity. The reproductive adaptation is the main reason for the morphological variation within populations ofA. marginata.

Ecomorphology of crabs and swimming crabs (Crustacea DecapodaBrachyura) from coastal ecosystems

Caranguejos braquiuros sao um dos grupos mais diversificados de crustaceos, ocorrendo na maioria dos habitats costeiros. Devido a alta diversificacao morfologica, procurou-se verificar a existencia de padroes morfologicos relacionados ao habitat desses animais. Foram analisadas 17 especies provenientes de manguezal, costao rochoso, praia de areia e ecossistema exclusivamente aquatico marinho/estuarino. Em cada ambiente um total de 16 medidas lineares foi obtido para machos e 17 de femeas. Foram discriminados tres grupos funcionais de especies de caranguejos, baseado em seu habitat: 1. Substratos complexos, 2. Semiterrestre, 3. Exclusivamente aquatico. As especies pertencentes ao grupo Substratos complexos apresentaram pernas ambulatorias longas, bem como heteroquelia relacionada a vida em substratos irregulares. Especies do grupo Semiterrestre apresentaram pernas ambulatorias de tamanhos distintos, o que lhes permite caminhar de maneira agil sobre o ambiente terrestre gracas a quarta perna ambulatoria maior e aos pedunculos oculares longos, importantes para a comunicacao visual. Especies do grupo Exclusivamente aquatico apresentaram as maiores larguras de carapaca e pedunculos oculares curtos. A presenca de distintas linhagens de caranguejos nos ambientes analisados permitiu demonstrar uma clara convergencia evolutiva, adaptando os caranguejos ao seu habitat e ambiente especifico.