Scielo RSS <![CDATA[Nauplius]]> vol. 28 num. lang. en <![CDATA[SciELO Logo]]> <![CDATA[Occurrence and distribution of early juvenile land hermit crabs at a small beach on the Boso Peninsula, Japan]]> Abstract The present study was conducted to examine the occurrence and distribution of early juvenile land hermit crabs of the genus Coenobita on a small beach on the Boso Peninsula, Japan as a basis for understanding the important habitats that land hermit crabs use during the sea-to-land transition. The survey sites were supratidal zones at six points with heterogeneous topography, and visual surveys for early juveniles were conducted from middle July to late October in 2015 and 2016. The number of empty gastropod shells in four quadrats along the intertidal zone at each point was also counted in the 2016 survey. The occurrence of early juveniles varied among survey points and was spatially stable for two successive years. The first appearance and abundance of early juveniles varied among survey years. Early juveniles were abundant at points with a gravel bottom throughout the intertidal zone, and empty gastropod shells were also abundant at these points. The abundance of early juveniles was highly correlated with the amount of empty gastropod shells. Thus, our surveys suggested the importance of the sediment types and abundance of empty gastropod shells in the intertidal zones for settlement and landing by land hermit crabs. <![CDATA[Detailed description of some mantis shrimp larvae and their implication for the character evolution within Stomatopoda]]> Abstract We present a documentation of the morphological details of two larval stages of mantis shrimps. Documentation was done using the autofluorescence capacities of the cuticle. This is the first time that morphological details of late mantis shrimp larvae are documented in great detail via photography, including all parts of the body up to the proximal elements of the appendages, and not presented as line drawings; it is the second time for mantis shrimp larvae in general. The description is presented as a standardized descriptive matrix. Documentation and description style are adjusted to facilitate comparison with fossil representatives of mantis shrimps, but also their extant counterparts, as well as specimens in the wider framework of Malacostraca and Eucrustacea. Through an exemplary comparison with fossil mantis shrimps, we provide indications about the early evolutionary history of the group. Through an out-group comparison, we identify several possible evolutionary changes of developmental timing, i.e., heterochrony, which could explain some morphological specialisations of mantis shrimps. <![CDATA[Growth and longevity of the spider crab <em>Libinia ferreirae</em> (Majoidea, Epialtidae)]]> Abstract We estimated the growth parameters of the spider crab, Libinia ferreirae (age, asymptotic size and growth rate) using the von Bertalanffy growth equation model. We obtained nine cohorts for female carapace asymptotic width (CW∞) = 64.32 mm, growth coefficient (day-1) (k) = 0.0027 e t0= 0.77 days) and seven for males (CW∞ = 81.93 mm, k= 0.0021 e t0= 0.49 days). The longevity for males was higher than that for females, estimated 2,156 days (5.91 years) and 1,706 days (4.68 years), respectively. The growth curves for males and females differed (F = 34.67 e p &lt; 0.001). Males reached gonadal maturity before morphometric maturity and occurred at 8.8 and 16.6 months of life, respectively. Females reach gonad and morphometric maturity synchronously and this was estimated to occur at about 11.42 months of life. These crabs invest a great amount of energy in growth during a brief period of their development until reaching the terminal moult. This growth strategy would bring less wear to the organism and consequently a greater longevity. <![CDATA[Association of <em><em>Epialtus brasiliensis</em></em> Dana, 1852 (Brachyura, Majoidea) with different species of seaweed]]> Abstract Seaweed aggregates form secondary substrates on rocky shores, providing habitats for phytal organisms such as the spider crab Epialtus brasiliensis Dana, 1852. This species is one of the most abundant macroinvertebrate component from seaweed communities. Although the literature suggests that E. brasiliensis lives in many species of seaweed, their density has only been reported in communities of Sargassum spp. This study assessed the density of the spider crab E. brasiliensis associated with the seaweed Sargassum cymosum Agardh, 1820, Hypnea musciformis (Wulfen) Lamouroux and Acanthophora spicifera (Vahl) Borgesen. We expected to observe a higher density of E. brasiliensis in S. cymosum, which shows greater morphological complexity, followed by H. musciformis, with intermediate complexity, and then by A. spicifera, with low complexity. We found that the density of these crabs can be as abundant in H. musciformis as has been previously reported for S. cymosum, but in both species, the density was higher than in A. spicifera. Overall, our findings improve the knowledge of the phytal habitats used by E. brasiliensis in rocky shore environments. <![CDATA[Two new records of terrestrial isopods (Isopoda, Oniscidea) from the state of Paraíba, Brazil]]> Abstract Two species of Oniscidea are recorded for the state of Paraíba for the first time. Cubaris murina Brandt, 1833 from Campina Grande and Cabaceiras and Porcellionides pruinosus (Brandt, 1833) from Campina Grande. Moreover, Alloniscus buckupi Campos-Filho &amp; Cardoso, 2018 and Atlantoscia floridana (Van Name, 1940) have their distribution extended, and a short discussion about the record of A. buckupi in a semiarid area is provided. <![CDATA[The rare porcelain crab <em>Novorostrum decorocrus</em> Osawa, 1998 (Anomura: Porcellanidae) from Indonesia]]> Abstract Novorostrum decorocrus Osawa, 1998, so far only known from its type locality, Iriomote Island, Ryukyu Islands, southern Japan, is herein recorded from much farther south, Ambon Island, Indonesia. Males and females of N. decorocrus differ from each other in some morphological traits and their morphological differences are also discussed and illustrated. The female of N. decorocrus is illustrated for the first time. The present record of N. decorocrus from Indonesia lends empirical support to a previous proposition, based on the duration of 12-14 days of the planktonic period of the zoeal phase, that the distribution range of N. decorocrus could possibly be wider than known at that time. <![CDATA[Dynamics of a subtropical population of the purse crab <em>Persephona punctata</em> (Decapoda: Brachyura: Leucosiidae) in Southeastern Brazil]]> ABSTRACT This study investigated the population dynamics of Persephona punctata with emphasis on population structure, sex-ratio, spatial distribution, maturity and reproductive period. Crabs and environmental factors (i.e., water temperature and salinity, and sediment texture and organic matter content) were collected monthly, from July 2012 to June 2014 in four sites within the Federal Environmental Protection Area of Cananéia-Iguape-Peruíbe: located in the oceanic area adjacent to the Cananéia region. The population had a female-biased sex-ratio. Persephona punctata had a seasonal reproduction and the higher percentage of ovigerous females (OF) occurred in spring and summer. There was a positive correlation (“lag 0”) between temperature and number of OF (cross-correlation, p &lt; 0.05) and a negative correlation between salinity and OF (“lag-2”), suggesting that periods of higher salinity may be favorable to larval hatching. The estimated size (carapace width - CW50) at the onset of gonadal maturity of males (35.0 mm) was larger than that of females (30.1 mm), which is a common feature of Brachyura. Our results extend the knowledge on the life history of P. punctata and may be useful for the development of future mitigation measures aimed at its conservation. <![CDATA[Population structure of <em>Hepatus pudibundus</em> (Decapoda: Aethridae) off the coast of Sergipe State, northeastern Brazil]]> ABSTRACT Shrimp trawling is an important socioeconomic activity but catches a large number of non-target species, including Hepatus pudibundus. This study aimed at assessing the population structure of H. pudibundus, analyzing its sex ratio, length distribution, size at first morphological maturity and biometric relationships, and identifying latitudinal patterns. Four samples of 6 kg (shrimps plus by-catch) were monthly collected in March/2015-May/2016 in Pirambu, Sergipe. Carapace width (CW) and length (LC), and total weight (TW, g) were measured. Sex and stage of morphological maturity were defined. A total of 240 individuals wes collected from all samples and the sex ratio did not differ from 1:1. This was observed in low latitudes, but females dominated in higher latitudes. The carapace width was 20.8-60.1 mm for females and 19.1-60.8 mm CW for males. Larger sizes were observed in higher latitudes. The estimated carapace width-length relationships for females and males were not significantly different (CL=0.6764+0.7390∙CW; sex grouped). The estimated weight-length relationship was TW=0.0004∙CW2.8568 for females and TW=0.0001∙CW3.1225 for males. When compared with previous studies carried out throughout the Brazilian coast, slope values (b) for weight-length relationships were higher for males. The length at first morphological maturity for females and males was 28.9 and 29.6 mm, respectively, the lowest ever recorded for this species, reflecting the occurrence of smaller sizes in lower latitudes. These results are the first obtained for northeastern Brazil. <![CDATA[First record of the deep-water xanthid crab genus, <em>Pulcratis</em> Ng & Huang, 1997, from the Indian Ocean, with description of a new species (Crustacea: Brachyura: Xanthidae)]]> Abstract The monotypic xanthid crab genus Pulcratis Ng and Huang, 1997, previously known only from the South China Sea, is recorded for the first time in the Indian Ocean. The new material was collected by commercial trawlers fishing off the coast of Tamil Nadu state, in southeastern India, and represents a new species, herein described. Pulcratis amabilis n. sp. is similar to the only other congener and type species, P. reticulatus Ng and Huang, 1997, in the general form and fresh coloration, but differs mainly in the outline of the carapace, and morphology of the chelipeds, and the male pleon and gonopods. The subfamilial classification of Pulcratis within Xanthidae is also discussed. <![CDATA[Growth, age at sexual maturity, longevity and natural mortality of <em>Alpheus brasileiro</em> (Caridea: Alpheidae) from the south-eastern coast of Brazil]]> Abstract We estimated the growth patterns, age at the onset of sexual maturity, longevity, and natural mortality of the snapping shrimp Alpheus brasileiro Anker, 2012. The sampling occurred monthly from April 2015 to March 2016 in the estuarine intertidal zone of Cananéia, São Paulo, Brazil. To estimate the growth parameters, all cohorts were adjusted to the Bertalanffy growth model. Longevity was estimated by the inverse growth equation. Natural mortality was calculated following the decrease in abundance over time of each cohort. We obtained the following estimates: CL∞ = 9.49 mm, k = 0.0077 day-1 (1.64 year-1), t0 = - 0.7628 for males, and CL∞ = 9.31 mm, k = 0.0095 day-1 (1.32 year-1), t0 = 0.0374 for females. The estimated age at the onset of morphological sexual maturity was 94 and 74 days for males and females, respectively. Females take 89 days to reach functional maturity, and have a higher mortality (4.35 year-1) than males (3.67 year-1). We rejected the hypothesis that males and females of A. brasileiro have the same growth patterns, longevity, mortality and, reaches sexual maturity at the same age. Our results suggest that physiological aspects and energy allocation strategies modulate the growth, longevity, and mortality of these snapping shrimps. <![CDATA[Tracking of spatial changes in the structure of the zooplankton community according to multiple abiotic factors along a hypersaline lagoon]]> Abstract In this study we evaluated the effects of changes in salinity, temperature, pH and dissolved oxygen on the spatiotemporal variation of zooplankton. Samples were collected in January−March, May; October−December 2010; and January−March 2011 in the Araruama lagoon, state of Rio de Janeiro, Brazil. There were eight fixed stations sampled using a WP2 net equipped with a flow meter. The zooplankton diversity of the Araruama lagoon was low and dominated by Cirripedia larvae and by the copepod Acartia tonsa, which is an indicator species of eutrophication. In general, a few species from the Cabo Frio region were able to adapt to the conditions of this hypersaline lagoon. In addition, a specimen of Monstrilla bahiana (Monstrilloidae) was found at a salinity of 46‰. This is the first record of the order Monstrilloida in the region of Cabo Frio. Temperature, salinity and pH were shown to be limiting factors for the species present in the lagoon since Cirripedia seemed to avoid releasing their larvae under unfavorable environmental conditions. The abundance of A. tonsa was always associated with that of Cirripedia larvae, and it was higher at cooler temperatures. <![CDATA[A new Northeast Asian <em>Lynceus</em> (Crustacea: Branchiopoda: Laevicaudata) with uniquely modified thoracopods and an evaluation of DNA barcoding for clam shrimp species identification]]> Abstract A new species of smooth clam shrimp (Branchiopoda: Laevicaudata) from Mongolia and China is described here based on both morphological and genetic differences. The new species, Lynceus grossipedia n. sp., has unique features, including asymmetrically modified male thoracopods (left side thoracopods III-VI), male claspers “movable finger” (=endopod) with delicate setation, and broad, bicarinate male and female rostrum. Lynceus grossipedia n. sp. is compared with the genera Paralimnetis Gurney, 1931 and Lynceiopsis Daday, 1912 and a recently described Lynceus Müller, 1776 from China, also showing modified male thoracopods. Lynceus mandsuricus Daday, 1927 is declared nomen inquirendum. DNA barcoding has not previously been applied on smooth clam shrimp taxonomy, so we generated new cytochrome c oxidase (COX1) data for 10 Lynceus species in order to explore its usefulness for Laevicaudata. Previous Laevicaudata sequences in GenBank were scarce (~50) and biased, with 62% (n=31) being assigned to a single taxon (i.e., Lynceus macleayanus) and 28% (n=14) not assigned to species. Based on the addition of new barcoding data and the comparison with GenBank data for other clam shrimps, we conclude that distance thresholds between species (=barcoding gap) are similar for all three suborders (Spinicaudata, Cyclestherida, and Laevicaudata). <![CDATA[New species of <em>Acanthochondria</em> Oakley, 1930 and <em>Chondracanthus</em> Delaroche, 1811 (Copepoda: Cyclopoida: Chondracanthidae) parasitizing marine fishes from Indian waters]]> Abstract This paper describes two new species of parasitic copepods of the family Chondracanthidae H. Milne Edwards, 1840. Acanthochondria krishnai sp. n. is described from Dollfus' stargrazer, Uranoscopus guttatus Cuvier, collected from Muttom and Colachel, Tamil Nadu, and Chondracanthus kabatai sp. n. from Silvery john dory, Zenopsis conchifer Lowe, collected from Neendakara, Quilon, Kerala, both along the southwest coast of India. Both the species are described and illustrated based on the fresh female and male specimens collected from India. Both the species are the first Indian representative of the respective genera. The checklist of Indian species of the family Chondracanthidae is also presented. <![CDATA[Redescription of the shallow water calappid <em>Mursia spiridonovi</em> Karasawa, 2018 (Brachyura: Calappidae) from India]]> Abstract Mursia spiridonovi Karasawa, 2018 known only from the western Indian Ocean, is the smallest species of the genus, measuring only 18 mm in carapace length. The species is redescribed from fresh material collected in Tamil Nadu in southern India. It is compared with similarly sized specimens of M. bicristimana Alcock and Anderson, 1894, all of which are immature. Mursia spiridonovi is characterised not only by its occurrence in shallow waters (less than 300 m depth) and small adult size but also by the prominently granular carapace and structure of the cheliped merus, male pleonal somites and gonopods. <![CDATA[The expansion of freshwater crayfish range to the center of Eurasia]]> Abstract Freshwater crayfish were previously absent in the territory stretching from the Caspian Sea basin to the Amur basin. That gap is now being filled, mainly due to the eastward invasion of the narrow-clawed crayfish Astacus leptodactylus, which has currently approached Lake Baikal. This invasion is the result of unauthorized releases. Further spread of the narrow-clawed crayfish or other crayfish species in Siberia may be expected. <![CDATA[Abundance and spatio-temporal distribution of the amphidromous shrimp <em>Macrobrachium olfersii</em> (Caridea: Palaemonidae) along the Ribeira de Iguape River (São Paulo, Brazil)]]> Abstract In this study we investigated the distribution of Macrobrachium olfersii (Wiegmann, 1836) along ~150 km of the Ribeira de Iguape river, São Paulo, Brazil. We compared the abundance and spatio-temporal distribution, and checked for differences in size and proportion of each sex in the collections, using two sampling methods. Shrimps were collected monthly at four sites (Eldorado, Sete Barros, Registro, and Iguape), from January to December 2007, using traps and sieves. We obtained a total of 23,818 individuals. The abundance was significantly higher at the Iguape-site, which was the closest to the estuary. There was a positive cross-correlation between abundance and rainfall, indicating an increase in abundance with a decrease in rainfall. The body size increased significantly upstream, suggesting a juvenile upstream migration, controlled by the rainfall regime and the amphidromous behavior of M. olfersii. More than 95% of the individuals were captured by sieving through the marginal vegetation of the river. The average size and sex ratio of each sample varied depending on the capture method: traps captured more and larger males than the sieve. Therefore, we recommend the combined use of these methods to obtain a better coverage of the population biology of freshwater shrimps. <![CDATA[Two new burrowing mud shrimps of the genus <em>Gilvossius</em> from the Gulf of Mexico (Crustacea: Decapoda: Callianassidae)]]> Abstract Previous reports of Gilvossius setimanus (De Kay, 1844) from the Gulf of Mexico have been based on a population of small specimens from deep offshore continental shelf waters off Texas and larger specimens from shorelines and shallow embayments of western Florida. The offshore population, herein designated Gilvossius fredericqae n. sp., reaches sexual maturity at much smaller size than does Gilvossius setimanus s.s. from the U.S. Atlantic seaboard, a species from which it differs in a number of morphological characters. While maturing at a similar size to G. setimanus s.s., a western Florida population, herein designated Gilvossius howellorum n. sp., differs from it in the 16S mt gene sequence, and from both it and the offshore species in morphology. An updated synonymy and rediagnosis of G. setimanus s.s. herein accompany descriptions of the two new species. <![CDATA[Neotropical freshwater crabs (Decapoda: Pseudothelphusidae) shred leaves]]> Abstract Freshwater crabs are macroconsumers that are commonly found in Neotropical headwater streams that may play a key role in energy flow and nutrient cycling in detrital food webs. Although studies have examined the feeding habits of trichodactylid crabs, little is known of this behavior in pseudothelphusid species, and specifically whether they actually consume leaf material. We conducted three nine-day laboratory trials with pseudothelphusid crabs (Ptychophallus tumimanus (Rathbun, 1898)) and leaves (Koanophyllon pittieri) to investigate whether crabs shred leaves. We hypothesized that leaf mass loss would be faster with crabs present relative to control tanks with only leaves. Leaf mass loss was significantly higher (p &lt; 0.001) in tanks with crabs (0.49 ± 0.07 g, mean ± 1 SD) compared to control tanks (0.31 ± 0.05 g). We observed crabs manipulating, shredding, and consuming leaves, with leaf fragments and egesta present in tanks with crabs but not in control tanks. Their consumption and egestion activity may affect nutrient availability and transformation by stimulating microbial activity during leaf breakdown and converting coarse particulate organic matter (CPOM) to fine particulate organic matter (FPOM). Therefore, freshwater crabs need to be considered when studying energy flow and nutrient cycling in detrital food webs of Neotropical headwater streams. <![CDATA[New species of freshwater crab genus <em>Kingsleya</em> Ortmann, 1897 (Decapoda: Brachyura: Pseudothelphusidae) from Piauí, northeastern Brazil]]> Abstract A new species of freshwater crab, Kingsleya parnaiba n. sp., collected in a tributary stream of the Parnaíba River Basin in Brazil, is described and illustrated. Kingsleya parnaiba n. sp. morphologically resembles Kingsleya attenboroughi Pinheiro and Santana, 2016 and Kingsleya gustavoi Magalhães, 2005, from which it can be separated by a set of characters of the first gonopod, chelipeds, and female abdomen. <![CDATA[On two species of <em>Periclimenaeus</em> Borradaile, 1915 (Caridea: Palaemonidae) from colonial tunicates in the southwestern Atlantic]]> Abstract Two species of the palaemonid genus Periclimenaeus Borradaile, 1915, P. ascidiarum Holthuis, 1951 and P. maxillulidens (Schmitt, 1936), are reported from the offshore Escalvada Island, Espírito Santo, Brazil. The location represents a new southernmost record for these species in the western Atlantic. Both species were found inside an undescribed tunicate species of Diplosoma, dwelling inside the circulatory channels, among the zooid clusters. Although P. ascidiarum is known to occur in tunicates, the finding of the rare P. maxillulidens inside an ascidian host represents the first record of this association. Illustrations for both species and a taxonomic key for the southwestern Atlantic Periclimenaeus are provided based on the present material and literature records. <![CDATA[Extension of geographical range and first record of <em>Trizocarcinus</em> Rathbun, 1914 (Brachyura: Euryplacidae) from the Western Tropical South Atlantic]]> Abstract Here, we report the first occurrence of Trizocarcinus Rathbun, 1914 (Brachyura: Euryplacidae) from the South Atlantic (Brazil). Trizocarcinus tacitus Chace, 1940 was collected in the upper continental slope of the Potiguar Basin, northeastern Brazil. The new record expands by 3000 km the southern distribution of the species in the Western Atlantic. <![CDATA[First record and range extension of the Jewel Box clam crab <em>Gemmotheres chamae</em> (Roberts, 1975) to the Gulf of Mexico, with comments on the systematics of the pinnotherines with a 2-segmented palp on the third maxilliped (Crustacea: Brachyura: Pinnotheridae)]]> Abstract An adult female of the Jewel-Box clam crab Gemmotheres chamae (Roberts, 1975) was collected from a shrimp trawl during a biological exploration off Campeche coast, Mexico. This finding represents its first record in the Gulf of Mexico and the second locality for this species along the Atlantic coast of America, the first being from off North Carolina, U.S.A. As an adult, G. chamae has a soft, thin carapace, and a subconical protuberance on article 1 of the antennae (with the nephridiopore of the antennal gland), so it is considered to belong to the Pinnotherinae sensu stricto. G. chamae and Nannotheres moorei Manning and Felder, 1996 (Atlantic) are the only members of the American Pinnotherinae sensu stricto that have the maxilliped 3 with a 2-segmented palp. The asymmetry of pereiopod 3 is confirmed, as well as that of the pereiopod 4, but the right legs are the longest. All these features are diagnostic for G. chamae.