Geographical variation and local environment effects in the reproductive output and fecundity of the shrimp Exhippolysmata oplophoroides (Decapoda: Caridea) in southeastern Brazil

We studied the shrimp Exhippolysmata oplophoroides in southeastern Brazil (Macaé, 22º37″S; Ubatuba, 23º55″S; and Cananéia, 25º53″S) to test the hypotheses that (1) females should have the same reproductive output and fecundity at the regional scale, and (2) these reproductive parameters can vary among regions. Maximum carapace length (Macaé = 13.1 mm, Ubatuba = 12.8, Cananéia = 16), fecundity, and reproductive output differed among regions (Ancova, p < 0.05). Females in Cananéia exhibited the highest reproductive output/fecundity (18.6%/5230 embryos), followed by those in Macaé (16.0%/4365 embryos) and Ubatuba (12.6%/1206 embryos). We found that fecundity/reproductive output varies inversely with the length of the reproductive season, i.e. a considerable amount of energy is allocated during seasonal spawning periods in subtropical regions such as Cananéia. Previous studies have proved that E. oplophoroides is able to reproduce continuously in Ubatuba, with probably minor but continuous energy investment in reproduction occurring in this tropical region. In contrast, although Macaé is located at tropical latitude, it is under the influence of Cabo Frio upwelling that alters the water’s physical properties via cold water intrusion. This process may be a determining factor in the spawning seasonality of Macaé’s shrimp population, justifying the higher reproductive output recorded here than in Ubatuba.     

Global diversity of crabs (Aeglidae: Anomura: Decapoda) in freshwater

The freshwater anomuran crabs of the family Aeglidae are all restricted to southern South America occurring in Chile, Brazil, Bolivia, Uruguay, Paraguay, and Argentina. The family consists of a single genus, Aegla, containing 63 currently described species. There are another 5–10 known yet undescribed species to complement this diversity. The aeglids occur in freshwater lakes, streams, rivers, and in caves with freshwater. The origin of the family appears to be from marine ancestors from the Pacific invading streams in Chile about 75 mya radiating both in Chile and again on the eastern side of the Andes, particularly in Brazil. Of the 63 species, 23 or 36.5% are considered under threat and are in need of conservation action. Guest editors: E. V. Balian, C. Lévêque, H. Segers & K. Martens Freshwater Animal Diversity Assessment     

Desiccation tolerance of four sympatric tropical intertidal hermit crabs (Decapoda,Anomura)

This study describes and quantifies the air exposure tolerance of four sympatric hermit crabs (Pagurus criniticomis, Clibanarius antillensis, C. sclopetarius, and C. vittatus) in an intertidal area in southeastern Brazil. We report on survivorship, percentage and rate of weight and water loss until death, and overall body water content. The coexisting populations showed similar percentages of overall body water content and weight and water loss until death. Survivorship depended on crab size rather than species, and was positively correlated with crab size within each species (linear relationship) and with the size of all individuals of this hermit crab assemblage (exponential relationship). Each species had a characteristic rate of weight and water loss, indicating the existence of different physiological adaptations to resist desiccation. These differences were directly related to the species’ distribution patterns in the intertidal zone.     

Functional morphology of the reproductive system of Galathea intermedia (Decapoda: Anomura)

Spermatophore formation in Galathea intermedia begins in the proximal part of the vas deferens. The contents subsequently form a spermatophoric ribbon, the so-called "secondary spermatophore," in its distal part. A strongly muscular ductus ejaculatorius is present in the coxa of the fifth pereiopod which builds up pressure for the extrusion of the spermatophoric ribbon. After extrusion, the ribbon is caught by the first gonopod, while the second gonopod dissolves the matrix of the ribbon. During copulation the spermatophores are randomly placed on the sternum of the female, near the genital opening, by the fifth pereiopods of the male. Subsequent ovulation of the female via the genital opening, an active process accomplished through muscular activity, results in fertilization of the eggs by the exploding spermatophores. External intersexes are characterized by both male and female external sexual characters, but in all individuals only male gonads are present. No trace of a female reproductive system could be detected. Thus, these external intersexes are exclusively functional males.     

Geographical variation in reproductive investment in Canada Geese (Branta canadensis) in Sweden

Summary Clutch volume, egg volume and clutch size were studied in four populations of introduced Canada Geese in Sweden along an 850 km latitudinal gradient. These recently established populations were not assumed to be adapted to their breeding habitats. Clutch volume as well as egg volume differed significantly between some of the populations. Clutch volume was significantly higher in a population which had its breeding area within spring feeding areas, compared to a population which migrated 350 km between the last major foraging area and the breeding area. Thus, we found some support for the energy reserve hypothesis, which predicts that the body reserves of the female determine her energy investment in the clutch. Egg size differed on a geographic basis, and one population had significantly smaller eggs than two of the others. Clutch size did not vary significantly between the populations. A significant year effect on clutch volume and clutch size was found.

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Zusammenfassung An vier Populationen in Schweden eingeführter Kanadagänse wurden einem Gradienten geographischer Breite folgend Volumina von Gelege und Eiern sowie Gelegegröße untersucht. Es ist nicht anzunehmen, daß diese erst seit kurzer Zeit ansässig gewordenen Populationen an ihre Bruthabitate angepaßt sind. Sowohl im Gelege- wie im Eivolumen zeigten sich signifikante Unterschiede zwischen einigen Populationen. In einer Population, deren Brutgebiet innerhalb der Weideflächen liegt, die die Vögel im Frühjahr aufsuchen, war das Gelegevolumen signifikant höher als in einer Population, die vom letzten bedeutenden Weidegebiet bis zu ihrem Brutgebiet ca. 350 km gezogen war. Die Energiereserve-Hypothese, die besagt, daß die Körperreserven des Weibchens seine Investition an Energie in das Gelege bestimmen, findet somit in unseren Ergebnissen etwas Unterstützung. Die Eigröße variierte von Brutgebiet zu Brutgebiet mit der geographischen Lage; eine Population wies signifikant kleinere Eier auf als zwei der übrigen. Nicht signifikant variierte die Gelegegröße zwischen den Populationen. Gefunden wurde ein signifikanter Effekt der jeweiligen lokalen Bedingungen auf Gelegevolumen und -größe.

     

Population structure and reproductive period of whitebelly prawn Nematopalaemon schmitti (Holthuis 1950) (Decapoda: Caridea: Palaemonidae) on the southeastern coast of Brazil

The population biology of Nematopalaemon schmitti in the Ubatuba region on the northern coast of the state of São Paulo was characterized through analyses of the length-frequency distribution, sex ratio, reproductive period, and juvenile recruitment. The specimens were caught monthly from January 1998 to December 1999, from a shrimp boat equipped with double-rig trawl nets. A total of 1073 specimens were analyzed, and the sex and carapace length (0.1?mm) of each individual were noted. The analyzed specimens consisted of 152 juveniles, 437 adult males, 296 adult females, and 188 ovigerous females (OFs). The monthly distribution of N. schmitti by size classes revealed a stable population structure, with both juveniles and adults continuously present. This population showed a unimodal distribution; however, bimodality was identified in June 1998 and 1999 for males, and June 1998 and July 1998 and 1999 for females, probably related to recruitment pulses of juveniles. Sexual dimorphism was indicated by the presence of females in the larger size classes, probably because of their growth rate. The proportion between males and females differed from 1?:?1 in certain size classes and seasons of the year (χ ²,?p?<?0.05); in some situations, the females were more abundant than the males, or vice versa. No significant relationship was detected between the seasonal mean temperatures of the bottom water and the percentages of OFs and young, or for the relationship between these two groups (Spearman, p?>?0.05). The continuous presence of OFs and young in the population suggests a pattern of continuous reproduction for N. schmitti in the Ubatuba region.     

红眼寄居蟹在实验室和野外条件下对贝壳的利用

占据适宜的贝壳对于寄居蟹的发育、繁殖和存活至关重要。尽管很多研究探讨了蟹类对贝壳的选择,但寄居蟹选择多大的贝壳仍不清楚。在实验条件下,本文作者用巴西Anchieta岛上野生红眼寄居蟹( Pagurusbrevidactylus)最常利用的黑衣蟹守螺( Cerithium atratum)和节桑椹螺( Morula nodulosa)进行了贝壳选择实验,通过回归分析确定目标贝类及其大小。观察到寄居蟹对一种独特贝类的选择具有性别意义,从而验证了野外观察结果。雄性明显地倾向选择黑衣蟹守螺的贝壳,而产卵和非产卵的雌性个体对腹足类贝壳的选择差异不显著。尽管两性之间对适宜贝壳的选择存在差异,贝壳适宜度指数(SAI)表明,种群占据那些足够大的贝壳(SAI =1·20±0·23)。红眼寄居蟹对贝壳利用的这种模式可能是为了避免与体型相似同域物种的竞争,从而在后来的生长中减少频繁地更换贝壳。根据目前的数据可以得到以下结论:红眼寄居蟹对贝壳的选择不仅取决于贝壳的参数,而且还与寄居蟹的个体和性选择有关[动物学报51 (5) : 813 -820 , 2005]。     

Spermatophore transfer in the hermit crab Clibanarius vittatus (Crustacea,Anomura, Diogenidae)

Although mating has been described in several hermit crab species, the mechanics of spermatophore transfer have not previously been demonstrated. Evidence from pleopod and gonopore morphology, video observations, and inseminated females indicates that in Clibanarius vittatus the male applies a spermatophoric mass directly onto the female via the gonopores rather than with modified pleopods 1-2 (gonopods) and/or genital papillae as in many other decapods. The single second pleopod of males of C. vittatus has a simple endopod with no apparent modifications for sperm transfer. There are no genital papillae extending from the male gonopores. The globular spermatophores are aligned in rows surrounded by a seminal secretion in the male ducts (vasa deferentia that terminate in ejaculatory ducts opening to the exterior via the gonopores). During copulation, described from time-lapse video recordings, the ventral surface of the last thoracic segment of the male, bearing the gonopores, was apposed to the ventral cephalothorax of the female. A massive amount of seminal secretion containing spermatophore ribbons, termed here the spermatophoric mass and described for the first time in a hermit crab species, was observed covering the sternites and coxae of pereopods 1-5 of a recently copulated female. It is suggested that during copulation the male emits the contents of the ejaculatory ducts directly onto the female without the aid of gonopods or genital papillae. Although spermatophore transfer is simple in C. vittatus, the presence of modified anterior pleopods or elongate genital papillae (sexual tubes) in other paguroidean species suggests the possibility of a more complex insemination process in these other hermit crabs.     

Geographical variation in the genus Dendrelaphis (Serpentes: Colubridae) within the islands of south-eastern Indonesia

The south-eastern islands of Indonesia between Bali in the west and Timor in the east define a region that is at the interface of the Asian and Australasian biogeographic regions. Three subspecies of the colubrid snake Dendrelaphis pictus have previously been recognized from the region: Dendrelaphis pictus pictus (Bali and Lombok); D. p. inornatus (Sumba to Timor); and D. p. intermedius (Sumbawa to Alor). A re-examination of Dendrelaphis pictus in this region uses multivariate statistics to examine the geographic variation in head-shield and body measurements within the species. The findings re-interpret the taxonomy, indicating that D. pictus from Bali and Lombok are specifically different from D. inornatus on the remaining islands on the Banda Arc. The populations of D. inornatus on the islands of Sumbawa, Sumba, Sawu, Flores, and Lembata are subspecifically different from those on Roti, Semau, Timor, Alor, and Wetar.
Several head-shield measures are strongly correlated with longitude within D. inornatus , suggesting environmentally triggered selection gradients. However, for many variables, the two subspecies differ significantly in the direction of the trends which suggests the subspecies respond differently to these environmental gradients. There is evidence that Dendrelaphis individuals may be transported through the islands by anthropogenic agencies.     

Evolutionary morphology of the hemolymph vascular system in hermit and king crabs (Crustacea: Decapoda: Anomala)

The morphological transformation of hermit crabs into crab‐like king crabs in the evolution of decapod crustaceans represents a remarkable case of carcinization or evolutionary shaping into a crab‐like form. In this study, we focus on internal organs such as the hemolymph vascular system and adjacent anatomical structures of several Recent hermit crab (Paguridae) and king crab (Lithodidae) species. There are various correspondences in the morphology of the arterial systems in the dorsal cephalothorax of the two taxa, especially with regard to the anterior aorta, anterior lateral arteries, and hepatic arteries. In the pleon, the posterior aorta in both taxa displays a proximal bifurcation and follows an asymmetrical course. The ventral vessel system, on the other hand, which mainly supplies the limbs, differs significantly between the taxa, with pagurids displaying the plesiomorphic condition. The pattern of the ventral vessel system in Lithodidae is influenced by morphological transformations of integumental structures during carcinization. One of these transformations was the broadening of the sternites, which resulted in a widening of the space between the endosternites. In addition, changes in the morphology of the endophragmal skeleton in Lithodidae led to an increase in the potential for intraspecific variability and interspecific variation in the arterial branching pattern. J. Morphol., 2013. © 2013 Wiley Periodicals, Inc.     

Phylogenetic systematics of the reptantian Decapoda (Crustacea, Malacostraca)

Although the biology of the reptantian Decapoda has been much studied, the last comprehensive review of reptantian systematics was published more than 80 years ago. We have used cladistic methods to reconstruct the phylogenetic system of the reptantian Decapoda. We can show that the Reptantia represent a monophyletic taxon. The classical groups, the 'Palinura', 'Astacura' and 'Anomura' are paraphyletic assemblages. The Polychelida is the sister-group of all other reptantians. The Astacida is not closely related to the Homarida, but is part of a large monophyletic taxon which also includes the Thalassinida, Anomala and Brachyura. The Anomala and Brachyura are sister-groups and the Thalassinida is the sister-group of both of them. Based on our reconstruction of the sister-group relationships within the Reptantia, we discuss alternative hypotheses of reptantian interrelationships, the systematic position of the Reptantia within the decapods, and draw some conclusions concerning the habits and appearance of the reptantian stem species.     

On the occurrence of Diogenes pugilator in the German Bight (Crustacea: Decapoda Diogenidae)

The occurrence of Diogenes pugilator in the German Bight has been examined since 2005. The steady onshore and offshore presence confirms that this southern species has established sustaining populations. The morphometric features are comparable to that of other populations in the adjacent Atlantic Ocean.     

Phylogeny of the Anomala (Crustacea, Decapoda, Reptantia) based on the ossicles of the foregut

We present a cladistic analysis of the Anomala based on 66 ingroup species and 5 outgroup representatives. Based on a comparative analysis of the morphology of the foregut we scored 124 characters related to size, shape, and fusion of foregut ossicles and other foregut structures. Our parsimony analysis resulted in 30 equally parsimonious trees which differ mainly at the lower hierarchical level. Our study reveals two large clades within Anomala. One large clade consists of Galatheoidea and Chirostyloidea. The internal relationships show a monophyletic Porcellanidae nested within a group comprising paraphyletic Galatheidae, and Munididae as well as Munidopsidae. The other large clade contains Aegla as sister group to a monophyletic group consisting of the Hippoidea and a clade formed by Lomis and the Paguroidea. Coenobitidae are nested within paraphyletic Diogenidae and Lithodidae are nested within paraphyletic Paguridae. The results are discussed in the context of other morphological and molecular analyses. Furthermore, some aspects of carcinization are touched upon; in particular, an anomalan stem species with a, at least to some extent, ventrally folded pleon is suggested.     

The Brachyura and Anomura fauna (Decapoda; Crustacea) in the Arvoredo Marine Biological Reserve on the southern Brazilian coast.

Eight species of Brachyura and two species of Anomura were registered for the first time on the Santa Catarina coast, in the waters around the Arvoredo Marine Biological Reserve. The animals were collected by scuba divers, between 3 and 22 meters depth, from September 2001 to February 2003. A total of 31 decapod species were collected, and most of the new occurrences had already been registered in the adjacent northern waters.     

Reproductive biology of the rock shrimp Sicyonia dorsalis (Decapoda: Penaeoidea) from the southeastern coast of Brazil

Summary

Sicyonia dorsalis is not commercially exploited in Brazil, but it forms a critical link in marine food chains by converting detritus food sources into microorganism biomass that is available for higher trophic levels. We examined the reproductive biology of this species, sampled for five and a half years in a tropical locality, the southeastern coast of São Paulo (23° S), Brazil. Monthly samples were taken from January 1998 to June 2003 at depths of 5 to 45 m. Degree of ovarian development was used to examine breeding in adult females. Recruitment was estimated by changes in proportion of individuals in juvenile size classes of carapace length (CL #8.2 mm) in relationship to the total number of individuals. The largest immature female measured 9.2 mm CL, but 75% of females were smaller than 7.3 mm CL. The largest immature male measured 6.8 mm CL. The relative frequency of reproductive females was negatively correlated with the relative frequency of recruitment (p <0.001). Reproductive females were found in every season, with peaks in December-February following the recruitment peak in March-June, and a second peak of spawning in May-July and of recruitment in September-November. The continuous reproductive pattern observed for S. dorsalis, combined with the hypothesis that during spring and summer the phytoplankton production is higher, when the South Atlantic central water mass intrudes into the region during upwelling events, suggests that food availability for protozoeal and mysis larvae may be an important selective factor shaping the seasonal breeding pattern for S. dorsalis. The classical paradigm of continuous reproduction at lower latitudes, with increased seasonality of the breeding period at higher latitudes, seems to be valid for this species.     

Temperature-driven biogeography of the deep-sea family Lithodidae (Crustacea: Decapoda: Anomura) in the Southern Ocean

Species’ distributions are dynamic and are linked to the changing physical environment. Temperature is considered to be a major factor influencing biogeography, especially in ectotherms such as the family Lithodidae. Lithodids are rare amongst decapods in their ability to inhabit the higher latitudes of the Southern Ocean; however, they are usually found in locations where water temperature is above 0.5°C. This study, for the first time, provides a baseline indication of the limits of the lithodid distribution around Antarctica, which will be instrumental in any future work on range extensions in this group. The distribution of lithodids is likely to change as temperatures along the West Antarctic Peninsula continue to rise, and range extensions by durophagous predators, such as the lithodids, are regarded as a potential threat to the unique structure of Antarctic continental-shelf ecosystems.     

Relative growth and sexual dimorphism in the hermit crab Clibanarius signatus Heller, 1861 (Anomura,Diogenidae) from the northern coast of the Persian Gulf,Iran

The purpose of this study was to investigate the relative growth and sexual dimorphism in the hermit crab Clibanarius signatus. The evaluation was done with 955 specimens (494 males, 251 females, and 210 intersexes) captured in Persian Gulf (Iran) during January to December 2015. Animals were submitted to measurements related to weight (BW, total wet weight) and body size related to cephalic shield (SW, width; and SL, length) and propodus of both chelipeds (CPL, length; and CPW, width). Males were larger and heavier than females and intersexes. Both males and females showed a negative allometric growth for the SL–BW and SL–SW relationships, but a positive allometric growth to intersex specimens. To SL–CPL relationship, a negative allometric growth was confirmed in males and females independent of the laterality of the CPL, whereas a contrast was verified in intersexes, with a positive allometric growth occurred for both hands. To SL–CPW relationship, a negative allometric growth (b < 1) occurred in females, independent of the laterality of the CPW, while in males, a positive allometric pattern was confirmed. In intersexes, this relationship was positive except for the right CPW which was isometric. Sexual dimorphism was evident in Clibanarius signatus, with males being the largest and females the smallest specimens in the population.