Showing papers in "Journal of Crustacean Biology in 2011"

Phylogenetic Analysis and Revised Classification of Podotrematous Brachyura (Decapoda) Including Extinct and Extant Families

Abstract: A phylogenetic analysis based upon 30 extinct and extant taxa of podotrematous brachyuran decapods using 74 characters shows that Podotremata sensu Guinot, 1977 is not monophyletic and results in a new classification for these crabs. Four new taxa are recognized at the section-level (Homoloida, Torynommoida, Etyoida, and Dakoticancroida) as well as two new families (Basinotopidae and Xandarocarcinidae). Dromiacea as historically defined is redefined herein to exclude Homoloidea. New generic names Noetlingocarcinus and Xandarocarcinus, and Seorsus millerae new combination also resulted from the work.

Description of the Agonistic Behavior of Aegla longirostri (Decapoda: Aeglidae)

Abstract: Among animals, conflicts are resolved through agonistic behavior, an expression of which embraces a range of fleeing behaviors, displays, up to the extreme of physical combat. This study aims to establish an observation protocol and to describe the aggressive acts of Aegla longirostri. Aeglids were collected in the field and kept for one week of acclimation in individual fishbowls with no contact with other animals. A total of ten pairs of males were paired, the members of each pair differing by no more than 1 mm in cephalothorax length. The behavioral acts were described from the combats videotaped for 20 minutes with each pair, of which 16 were considered aggressive acts. The animals took an average of 198 seconds to start combat. A table of aggression intensity was established, ranging from −2 (fleeing) to 5 (intense combat). There was a significant difference between winners and losers in the time spent in the different levels of intensity and in the duration of the acts performed. Aegla long...

Biogeography of the Freshwater Decapods in the La Plata Basin, South America

Abstract: The distributions of freshwater fauna in the La Plata Basin, including decapods, are dynamic; their actual distributions depend on not only their movements but also on environmental fluctuations. The La Plata system has a diverse range of environments, which are colonized by crustaceans with complex evolutionary histories. Our aim was to elucidate the distribution patterns and relationships of current freshwater decapod fauna in terms of the different geo-climatic processes at work in the La Plata system. We recognized 13 zones based on their unique environmental characteristics. Species lists were assembled through field samples, examination of museum collections, and literature analysis. Faunistic similarity was evaluated using the Jaccard index and cluster analysis. A parsimony analysis of endemicity (PAE) was applied to determine the most parsimonious of all possible tree topologies. There were 69 species freshwater decapods analyzed in the La Plata Basin. The Mata Atlantica (MA), Parana Supe...

First Description of a Pure-Search Mating System and Protandry in the Shrimp Rhynchocinetes uritai (Decapoda: Caridea)

Abstract: Previous studies on two species of the genus Rhynchocinetes (“hingebeak” shrimps) have described mating systems in which large dominant “robustus” males, with hypertrophied cheliped and third maxilliped weaponry, guard and defend smaller females during copulation. The sexual system of these species is gonochoric (separate sexes). In this preliminary study on the sexual biology of R. uritai, we report observations indicating a very different sexual and mating system for Rhynchocinetes. A sample of R. uritai taken off Shimoda, Japan, revealed a population structure with small males and large females with no overlap in size. Two intermediate-sized individuals showed transitional sexual characteristics indicating sex change from male to female (protandrous sequential hermaphroditism). Transitional individuals had male sexual appendices but also were developing female “breeding dress” (incubatory) characters. Furthermore, these individuals had large vitellogenic oocytes in the gonads, typical of matur...

Life cycle and population structure of aegla paulensis (decapoda: anomura: aeglidae)

Abstract: We describe growth, longevity, sex ratio, reproductive period, and recruitment of Aegla paulensis from JaraguaState Park, Sao Paulo, Brazil (23u27927.90S; 46u45932.30 W). The population was sampled monthly (September 2007 through August 2009) with the aid of traps. Over five thousand individuals were captured, sexed, measured (carapace length 5 CL) and inspected for reproductive traits (females only), and then released back to the sampling site. The pattern of the reproductive cycle was strongly seasonal (austral mid autumn through late winter), with a single recruitment pulse per year. The obtained von Bertalanffy growth equations were CL 5 21.25(1-e 20.041(t + 1.250) ) and CL 5 16.52(1-e 20.049(t + 1.823) ) for males and females, respectively. Males (mean CL 6 SD 5 11.86 6 2.79 mm) attain larger sizes than females (mean CL 6 SD 5 10.84 6 2.36 mm). Aegla paulensis reproduces twice during an estimated life span of 40.2 months for females and 33.9 months for males. Temporal variation of sex ratio showed a distinctive pattern characterized by a sequence of three distinct periods that repeated from one year to another, and which suggested that a behavioral component influence the proportion of sex in adult specimens sampled with traps during reproductive and non-reproductive periods.

Evaluation of a Crayfish Burrowing Chamber Design With Simulated Groundwater Flow

Abstract: Crayfish are a highly diverse group of freshwater crustaceans with great ecological and economic importance. Many species construct terrestrial burrows within which they reproduce, overwinter, and/or avoid desiccation. Basic life-history and environmental tolerance information is still lacking for many species, particularly in regards to terrestrial portion(s) of their life cycle. In this paper we present and evaluate a design for a crayfish burrowing chamber that allows for experimental control of burrowing conditions, including substrate, groundwater height and flow, as well as direct observation of burrow construction and measurement of groundwater quality. Results of evaluation assays with Cambarus striatus, a widespread secondary burrower native to the southeastern United States show that chambers are amenable to studies examining burrowing behavior, survivorship, growth and water quality. Water table height was easily manipulated in chambers. Seepage rates were strongly affected by substrat...

Phylogenetic Analysis of Ridgewayia (Copepoda: Calanoida) from the Galapagos and of a New Species from the Florida Keys With a Reevaluation of the Phylogeny of Calanoida

Abstract: The mitochondrial gene cytochrome-c oxidase subunit 1 (COI) and the nuclear ribosomal DNA region known as Internal Transcribed Spacer 1 (ITS1) are used in a phylogenetic analysis of Ridgewayia from the Galapagos Islands and of a new species, Ridgewayia tortuga, from the Florida Keys. In addition, the phylogeny of Calanoida is reconstructed based on the 18S ribosomal RNA gene. The following characters exclude R. tortuga from the three recognized species groups of Ridgewayia: the presence of only 7 setae on the terminal endopod segment of leg 2; a 20-segmented male right antennule with two geniculations, the first between segments 9 and 10 and the second between segments 16 and 17; and details of the male fifth leg, in particular the elongate, unarmed, right endopod with a bifurcated tip. The molecular analysis shows that the first half of the COI gene not only fails to differentiate the various species of Ridgewayia, but it also fails to differentiate between the families Ridgewayiidae and Pseudocyclopidae. The second half of this gene and the ITS1 region are species specific. Molecular and morphological evidence suggest that the Galapagos ridgewayiids are the result of one colonization event and that the current phylogeography of these animals can be explained by a combination of vicariance and active migration models. The 18S ribosomal RNA gene proves successful in the reconstruction of the phylogeny of Calanoida with the following main conclusions: 1) Centropagoidea is the sister branch to all other Calanoida; 2) Ridgewayiidae and Pseudocyclopidae likely share a common ancestor with Augaptiloidea; 3) Ridgewayiidae and Pseudocyclopidae should be included in the same superfamily, the Pseudocyclopoidea; and 4) Spinocalanoidea likely needs to be included in Clausocalanoidea to recover the monophyly of the latter superfamily.

External Morphology and Post-Embryonic Development of Derocheilocaris remanei (Mystacocarida) Revisited, With A Comparison to the Cambrian Taxon Skara

Abstract: A re-description of the post-embryonic development of Derocheilocaris remanei Delamare-Deboutteville and Chappuis, 1951 (Mystacocarida) is presented. It includes nine stages, not ten as originally described. The first stage already has a maxillula (though not fully developed) and is, therefore, not an ortho-nauplius as previously reported. Particular focus is on the development of the post-mandibular appendages (maxillula, maxilla, maxilliped) that undergo significant changes during ontogeny, and the development of the so-called ‘toothed furrows’, all of which are good indicators of changes between the stages. The maxilla and maxilliped are quite different from each other in the adult stage, but they develop in a very similar manner, showing very similar morphologies at certain stages. None of the post-mandibular appendages has a fully formed coxa, but only a proximal endite, which is in contrast to some previous interpretations. The development of D. remanei was originally considered very different from that of its transatlantic ‘sister species’, D. typicus, but our observations indicate that this is not the case. Rather, the development of D. typicus and D. remanei is very similar. This implies that not only the adult morphology of Mystacocarida is remarkably conservative, but also the larval sequence. With regard to the feeding system, mystacocaridans have a cephalo-thoracic feeding apparatus including the first pair of trunk limbs modified as maxillipeds, which collaborate with the maxillulae and maxillae in the feeding process. All three limbs are very similar to each other (the main difference is that the maxilliped possesses a vestigial exopod). The feeding system is in both general aspects and in particular details very similar to that of Copepoda and the representatives of the Cambrian taxon Skara. This suggests a close relationship between these three taxa, for which we propose the name Copepodoida. The name refers to specific features found exclusively in copepodans and, in our view, mystacocaridans and the three species of Skara.

Multi-Locus Phylogeny of Sponge-Dwelling Snapping Shrimp (Caridea: Alpheidae: Synalpheus) Supports Morphology-Based Species Concepts

Abstract: Alpheid snapping shrimp are one of the most diverse groups of coral-reef fauna, and sponge-dwelling shrimp in the genus Synalpheus (gambarelloides species group) have in particular become a model system for studying the evolution of social biology and host use in marine invertebrates. Despite recent advances in understanding the evolution and systematics of Synalpheus, the taxonomy and phylogenetic relationships within this group remain challenging. More than 20 new species in the S. gambarelloides species group have been described over the past two decades, primarily within several cryptic species complexes, which has doubled the known diversity of this group in the West Atlantic. Here we construct a new phylogenetic tree describing relationships between 40 different species from the S. gambarelloides-group (119 individuals from across the Caribbean), using a combined dataset consisting of two mitochondrial loci (16S and COI), one nuclear protein-coding gene (elongation-factor 2), and 33 morphological characters. Putative conspecific specimens of Synalpheus from multiple locations across the Caribbean were always monophyletic (with one exception), providing strong support for the validity of species concepts based on morphology. Our study also provides further evidence for the monophyly of the S. gambarelloides-group in the Caribbean, resolves the molecular relationships within many recently described species complexes, and provides a new phylogenetic framework for future evolutionary studies of this group.

Life History of Three Fairy Shrimps (Branchiopoda: Anostraca) from Thailand

Abstract: Life table characteristics of three species of fairy shrimps from Thailand, Streptocephalus sirindhornae, S. siamensis, and Branchinella thailandensis are reported, based on laboratory cultures at 24-26°C. Comparative data on their growth and fecundity revealed that B. thailandensis had the largest size (male 26.2, female 27.8 mm) and the highest hatchability 87.67%. The shortest hatching time was found in B. thailandensis, it hatched within 3 days, while the other two species hatched within four days. Branchinella thailandensis showed more rapid growth than the other two species, and it reached maturity within 6.5 days. In contrast, S. sirindhornae had the highest fecundity, producing a mean of 35.3 broods and 17,865 eggs per individual female over its life time, whereas the other two species produced less than 8000 eggs. Life span was equal for both males and females in all three fairy shrimp species (P > 0.05). In this study, the fecundity data indicated that the number of eggs per brood recor...

Reproductive Biology of the Pandalid Shrimp Plesionika izumiae (Decapoda: Caridea)

Abstract: The pandalid shrimp Plesionika izumiae is a relatively common shrimp in the coastal waters of Japan, except off northern Honshu and Hokkaido. This is one of the dominant species in the benthic community of Kagoshima Bay, southern Japan. The reproductive biology including, reproductive period, size at sexual maturity, embryo size and brood size of P. izumiae was studied in the bay. All females were examined for the presence of embryos attached to the pleopods and the developing embryos were classified into four stages. Ovarian development was also observed based on morphological observation. Ovigerous females occurred throughout the year with higher percentage during May to November, indicating this was the main reproductive period. Ovarian maturation was observed during the incubation process of embryos, suggesting that females were potentially capable of multiple spawning during a reproductive period. The size at sexual maturity was estimated to be 8.5 mm in carapace length based on the method u...

On the occurrence of afropinnotheres monodi manning, 1993 (decapoda: pinnotheridae) in european waters

Abstract: Heretofore, the pinnotherid crab, Afropinnotheres monodi, had been recorded only from African waters. The range is now extended into European waters with discovery of material in the Gulf of Cadiz. Furthermore, early collections of material had occurred only in open water; now three hosts can be assigned, the clams Scrobicularia plana, Ruditapes decussatus and Cerastoderma glaucum. Further discoveries of this pinnotherid may now be expected, especially along the coast of Portugal.

Molecular-Based Method To Distinguish the Sibling Species Hemigrapsus penicillatus and Hemigrapsus takanoi (Decapoda: Brachyura: Varunidae)

Abstract: In this study, we developed a simple and rapid restriction fragment length polymorphism (RFLP) method to distinguish the sibling species Hemigrapsus penicillatus and H. takanoi based on interspecific base substitutions within the 16S rRNA region of mitochondrial DNA. Sequencing and alignment of partial sequences revealed two haplotypes for H. penicillatus and one for H. takanoi, and five species-specific base substitutions. Digestion of the PCR products using the restriction endonuclease Dde I produced a banding pattern that was consistent with species identification based on morphological and pigmentation patterns. The sequence for H. takanoi collected in Japan showed high homology with that reported for specimens collected in Europe. This method could be useful for identification of these two species by researchers without specific taxonomic knowledge.

Phylogeny and Evolution of Mecochiridae (Decapoda: Reptantia: Glypheoidea): An Integrated Morphometric and Cladistic Approach

Abstract: This study provides a systematic and phylogenetic overview of the extinct reptant decapod family Mecochiridae. Mecochiridae are distinguished from both their traditional out-groups, Glypheidae and Erymidae, using cladistic and geometric morphometric techniques. Cladistic analysis of 12 species using 21 traditional and new characters verifies the in-group genera Mecochirus and Pseudoglyphea. Glyphea emerges as a sister group to Pseudoglyphea, suggesting a re-assignment of the genus to Glypheidae. The genus Meyeria is recovered as paraphyletic, suggesting the establishment of a new taxonomic group for species of Meyeria that exhibit a posterior tuberculated ridge, a well-developed hepatic bulge or ridge, and unornamented pleura. Both relative warp and Eigenshape analysis of the carapace and groove patterns that have long been used as descriptive morphological features succeeded in highlighting modes of shape change that when subjected to a discriminant analysis proved useful in distinguishing members of Mecochiridae. This study shows that landmark geometric morphometric methods and eigenshape analysis can be used to investigate the fidelity of existing taxonomic groupings based on other methods, and that an integrated cladistic and morphometric methodology has the potential to aid in resolving relationships among other unknown or problematic fossil taxa.

Morphologic Variation in Aegla Leach (Decapoda: Reptantia: Aeglidae) from Central-Southern Chile: Interspecific Differences, Sexual Dimorphism, and Spatial Segregation

Abstract: How do certain characteristics of organisms, such as sex or species, and certain ecological factors, such as interaction with congeneric individuals, influence the variability of body architecture in an environmental setting over a small spatial scale? Using geometric morphometrics we performed a morphological comparison of the dorsal surface of the carapace of a congeneric guild formed by Aegla araucaniensis, A. denticulata denticulata, and A. abtao. Additionally, we evaluated whether the segregation of microhabitat by congeneric interactions generates variations in the shape of the cephalothorax in A. araucaniensis, comparing a population belonging to the congeneric guild with a close population without congeneric interactions. Changes in cephalothoracic shape are regulated primarily by intrinsic factors, such as the differences between species and sex of individuals. In addition, the congeneric interactions do not affect the expression of the carapace shape in either of the populations of A. a...

Field Observations on Selective Tidal-Stream Transport for Postlarval and Juvenile Pink Shrimp in Florida Bay

Abstract: Postlarvae and juveniles of pink shrimp were collected in the summers of 2005 and 2006 at three stations in northwestern Florida Bay, the main nursery ground of this species in South Florida. Collections were made at one- or two-hour intervals during three full moon nights and two new moon nights at depth intervals in the water column. Results of the five collections were consistent with the assumption that postlarvae use a flood-tide transport (FTT) to advance into the estuary by ascending in the water column during the darkflood tide and resting near the bottom during the ebb tide. Evidence of a FTT were higher numbers of postlarvae per hour collected during the flood tide vs. ebb tide and the large number of postlarvae collected with highest velocity flood tide currents. ANOVA indicated significant differences in the number of postlarvae collected between tidal stages and moon phases, but not among depths. Postlarvae were more abundant during new moon than full moon. We also found different patterns of postlarval distribution between the new and full moon. During the new moon, a large peak of postlarvae occurred coincident with highest current speeds, whereas, with one exception, during the full moon postlarvae were more abundant in the second half of the flood period near the slack tide. In contrast, juveniles exhibited a behavior and migratory pattern opposite to that of postlarvae. ANOVA indicated significant differences between the number of juveniles captured between tidal stages and among depths, but not between moon phases. Juveniles were found almost exclusively near the surface on the ebb tide. Significantly larger juveniles were captured on the dark-ebb rather than on the dark-flood tide during both moon phases, suggesting that older juveniles were leaving the Bay on the ebb tide.

Morphologic and Genetic Variation in Triops (Branchiopoda: Notostraca) from Ephemeral Waters of the Northern Chihuahuan Desert of North America

Abstract: Tadpole shrimp are known to be important animals in the ecology of ephemeral wetlands In the northern Chihuahuan Desert of North America, the tadpole shrimp fauna is composed of possibly three species in the genus Triops, which have variously been referred to as species, subspecies, and intraspecific variation Our results support the presence of three morphologically distinct forms, which will be referred to herein as T newberryi, T longicaudatus “short,” and T longicaudatus “long” We report analyses of Triops spp sampled in summer 2008 from 14 natural playas and man-made flood retention ponds Data were recorded on meristic counts and quantitative measurements of morphological features We also sequenced portions of the mitochondrial COI and ND1 genes for 72 shrimp, including individuals from all three morphological forms and for multiple ponds for each form where possible The three forms were morphologically distinct for multiple characters and molecular analyses showed large difference

Body and Claw Size At Autotomy Affect the Morphology of Regenerated Claws of the Sand Fiddler Crab, Uca pugilator

Abstract: Sand fiddler crab males, Uca pugilator (Brachyura: Ocypodidae), use their single enlarged claw as a weapon in fights for burrows and as a signal to attract females to burrows. Seventy-three males from a South Carolina marsh were in reared in the laboratory to determine if body size at the time of claw loss affects the morphology of the claw that subsequently regenerates. Thirty-six males were induced to autotomize claws and regenerated new ones. Thirty-seven males retained original claws. Across four molts, males regenerating claws gained more in claw length but less in body width and overall mass than males retaining original claws. The first molt accounted for these differences as males regenerating claws gained relatively little in body size but added much in claw length. Regenerated claws were more slender, having smaller dimensions of the manus relative to claw length. As the manus houses the claw closer muscle, regenerated claws are expected to be less powerful and appear more designed for ...

The Southernmost Freshwater Anomurans of the World: Geographic Distribution and New Records of Patagonian Aeglids (Decapoda: Aeglidae)

Abstract: Aegla alacalufi and A. neuquensis are exclusively found in freshwater systems of Patagonia. The geographic distribution range of A. alacalufi is vast and fragmented, covering continental and insular rivers. A new record of this species on Duque de York Island (50°34′S-75°20′W) defines the southernmost limit for the distribution of freshwater anomuran crustaceans. Aegla neuquensis is only found in Extra-Andean Patagonian rivers. The current geographic distribution patterns of these species can be explained by the existence of multiple island glacial refuges during the Last Glacial Maximum and by the hydrographic captures that occurred during the Late Glacial.

Crayfish Fauna of Southeastern Pennsylvania: Distributions, Ecology, and Changes Over the Last Century

Abstract: We describe the current distributions and relative abundances of southeastern Pennsylvania's crayfish; changes in the region's crayfish fauna over the last century; and, where pertinent, the relationship of the current fauna to site-specific characteristics, basin-wide attributes, and exotic crayfish. The crayfish fauna currently inhabiting the region bears little resemblance to the historical assemblage. Whereas historical surveys yielded Orconectes limosus and Cambarus bartonii, both native species, recent collections produced eight species including five exotics. Many areas occupied by exotic Orconectes no longer support O. limosus. Cambarus bartonii was found in a number of invaded systems, but was typically a minor component of the crayfish community and may not be able to persist in those systems indefinitely. The distribution of Cambarus (Puncticambarus) sp., an undescribed member of the Cambarus acuminatus complex, was extremely limited, with populations only found in four streams, all of...

Chromatosomes In Three Phenotypes of Neocaridina denticulata Kemp, 1918: Morphological and Chromatic Differences Measured Non-Invasively

Abstract: External colour differences in crustaceans were examined using a non-invasive study of morphology and colour in epidermal chromatosomes. Three different phenotypes of the shrimp, Neocaridina denticulata (< 2 cm total length), differ in the quantity and dispersal of chromatosomes in the epidermis, with resulting differences in body colour. Also, pigmentation pattern is most pronounced in the anterior body parts. The exopod of uropod was the most suitable body area to monitor colour changes in this shrimp. This non-invasive method allows for the study of external pigmentation in crustaceans at different stages and may help to understand how these animals manipulate their chromatosomes under physiological and environmental variability in order to acquire the final external colour.

Species Discrimination of Postlarvae and Early Juvenile Brown Shrimp (Farfantepenaeus aztecus) and Pink Shrimp (F. duorarum) (Decapoda: Penaeidae): Coupling Molecular Genetics and Comparative Morphology to Identify Early Life Stages

Abstract: We collected postlarvae (PL) and early juveniles of Farfantepenaeus aztecus and F. duorarum , 7.0 mm CL from the Gulf of Mexico and verified their species identity using a multiplex Polymerase Chain Reaction (PCR) assay, which targeted the 16S rRNA mitochondrial gene. We examined young with $ 5 dorsal teeth (DT) for differences in morphology and used a General Discriminant Analysis approach and ‘best’ subsets model-building technique to help identify the ‘best’ characters to discriminate taxa and predict species membership. Farfantepenaeus duorarum with $ 5 DT and F. aztecus with $ 7 DT have spinules on the epigastric and first DT, a character not previously reported for these two species. Differences in antennal scale shape and sixth pleomere length discriminate . 95% of Farfantepenaeus sp. with , 7–8 + 2 rostral teeth. Farfantepenaeus duorarum has an antennal scale with an acutely rounded margin about twice the height of the adjacent lateral spine, and has a sixth pleomere length measurement , 2.5 mm. In F. aztecus, the antennal scale has a more broadly rounded margin with a lateral spine that approaches or exceeds the tip of the scale, and has a sixth pleomere length measurement . 2.5 mm. Species discrimination of Farfantepenaeus sp. with $ 7–8 + 2 rostral teeth requires body measurements. Classification models accurately discriminate . 90% of Farfantepenaeus sp. from the western Gulf and increase the reliability of discrimination by . 20% over characters that have been used for species discrimination, some of which are unreliable. The unsatisfactory performance of the models in discriminating Farfantepenaeus sp. from the eastern Gulf is consistent with the possibility of different ecological populations in the eastern and western Gulf that may warrant further study. Integration of molecular taxonomy and comparative morphology, as we did here, can provide insight into the patterns of diversity and ecological and evolutionary principles that encompass fisheries management.

Plankton-Caught Zoeal Stages and Megalopa of the Lobster Shrimp Axius serratus (Decapoda: Axiidae) from the Bay of Fundy, Canada, With A Summary of Axiidean and Gebiidean Literature on Larval Descriptions

Abstract: Wild-caught larvae, attributed to the lobster shrimp Axius serratus, consisting of two zoeal stages and a decapodid (megalopa), are described in detail. Parentage of larvae was ascertained based on geographic distribution of axiideans and gebiideans ( = former thalassinideans) within the study area and close morphological resemblance to other congeneric larval stages. Larvae of A. serratus represent the first described ‘thalassinidean’ larvae from Canadian Atlantic waters and the first for Axiidae within the northwest Atlantic. Among axiidean larvae, those of A. serratus most closely resemble larvae of A. stirhynchus from the eastern Atlantic. Distinct features include the spination of the pleon that set A. serratus zoeae apart from those of most other ‘thalassinideans’ but that, in combination with a telson very similar to Homarus americanus, contributes to the general resemblance of A. serratus larvae to those of the American lobster. The primary distinction between these taxa is the presence ...

Toward a taxonomy of the Gnathiidae (Isopoda) using juveniles: The external anatomy of Gnathia aureamaculosa Zuphea stages using scanning electron microscopy

Abstract: The juvenile stages of the isopod family Gnathiidae have a large impact on marine ecosystems through their parasitic interactions with marine fishes, as well as being a substantial food source for the cleaner fish guild. However, the taxonomy of Gnathiidae is based on non-feeding adult males. Adults are difficult to obtain owing to their cryptic lifestyle in the sea floor, while the juveniles can be collected in abundance either from their hosts or using emergence traps. Given the known diversity of the hosts, and assuming host partitioning among species, the diversity of gnathiids could be much greater than currently recognised. We argue that the systematics of this group should recognise this ecological role, and develop the taxonomy of the juvenile stages. We provide a detailed external anatomy of one species, Gnathia aureamaculosa, that has been used extensively in recent ecological studies. Images from scanning electron microscopy of two juvenile instars are compared with two other species, and the literature surveyed to illustrate a range of taxonomically useful traits. The expansion cuticle of the pereion shows how gnathiids are able to expand enormously during a blood meal and also lends caution on using total body length for comparative purposes. A range of morphometric and categorical features are available on the non-expandable sections of the body, such as the head, pleotelson and uropods. Of the three species illustrated, the shape of the eyes and head, and the shape and setation of the pleotelson uropods are diagnostically useful. Evidence from the literature shows that the free-living juveniles are not mancas; the manca instars are passed during the internal developmental period. Anatomical observations cast doubt on the classification of Gnathiidae as Cymothoida, in agreement with recent phylogenetic studies.

Acrothoracica, Burrowing Crustaceans

Abstract: This monograph is the first major overview of the order Acrothoracica since Tomlinson (1969). This is an exclusively marine group of gonochoristic (dioecious) barnacles. Females, generally accompanied by one or more dwarf males, excavate burrows largely in carbonate substrates and are therefore referred to as the burrowing barnacles. While their greatest diversity is found in shallow tropical seas, the most generalized or primitive members are found for the most part in deep water (between 1000 and 3000 m). Trace fossils, ranging back to the Devonian if not the Ordovician (Taylor and Wilson, 2003), reveal that species once occupied relatively high latitudes in Northern Europe and Gondwanaland, and at least one extant species is known from Antarctic waters today. The author, Gregory Kolbasov, dedicates this work to his late professor, Galena Zevina, whose premature death in 2002 constituted a major setback for cirripedology in general (Kolbasov et al., 2005). The dedication and the bulk of the following text are in Russian, but a 25-page summary and some two-thirds of the references are in English. Furthermore, the ordinal, familial, and generic diagnoses, and the characters used in the cladistic analysis, are also in English. Regrettably, for the English-speaking reader the key to the genera and species is in Russian, but this is in good part compensated for by 153 well-executed line drawings, SEMs, and charts, all of which have captions in English as well as Russian. All in all, this is a volume most any serious worker on crustaceans as well as cirripedes would want close at hand, at least until a promised multi-authored English version becomes available. The work lacks a general subject index, but there is a computer-generated one for hosts as well as the acrothoracican taxa, and the pages where definitions are to found in boldface. Even so, not to be able to easily find a species in the index by its trivial name alone can be inconvenient, especially if it is one of the 10 or so whose generic name has recently changed. The revisionary aspects of this monograph include a taxonomic reorganization whereby the families Lithoglyptidae Aurivillius, 1892 and Cryptophialidae Gerstaecker 1866 (heretofore included in the suborder Pygophora Berndt, 1907) are split between two new orders, Lithoglyptida nov. and Cryptophialida nov., whereas Trypetesidae Stebbing, 1910 (heretofore the sole family of Apygophora Berndt, 1907) is now placed in Lithoglyptida along with Lithoglyptidae (Table 1). As can be seen in the table, Tomlinson’s monograph included two orders, three families, nine genera, and a modest diversity of 37 species. Since Tomlinson, while the number of genera has increased from but 10 to 11 [including Balanodytes taiwanensis (Utinomi, 1950) which, while cross-referenced, was inadvertently left out of the text (cf. Kolbasov and Newman, 2005, present status), the number of species has risen to approximately 63, i.e., almost double. However, not only has it turned out that an inference of Kolbasov’s that Balanodytes Utinomi, 1950 was a junior synonym of Armatoglyptes (Kolbosov and Newman, 2005) was correct, but also it has been determined that Balanodytes taiwanensis Utinomi, 1950, Lithoglyptes habei Tomlinson, 1963, and Lithoglyptes balanotytes Kolbasov, 2000 are synonymous of Armatoglyptes taiwanensis (Utinomi, 1950) [BKK Chan, personal communication]. The portion of the monograph in Russian is divided between 6 chapters; 1) Historical background, 2) Morphology of females and dwarf males, 3) Embryology and larval (naupliar and cyprid) development, 4) Phylogeny and classification, 5) Geographical distribution, and 6) Female-host interactions. This is followed by a summary in English that, while sidestepping the historical introduction, subdivides the remaining material between 8 rather than 6 chapters or sections. The first of the 8 sections is on external functional morphology and the polarity of evolution in females, males being taken up in section 3. Here the evolution of various parts is discussed, and interesting trends are noted, such as a correlation between reduction in the size of the aperture and the number of cirri. The second section concerns the presence of a calcareous plate in acrothoracicans, first reported upon in the deep-sea species, Weltneria hessleri and W. exargilla (cf. Newman, 1974). It was believed at that time the acrothoracicans had a pedunculate ancestry, a notion stemming from Darwin and promulgated by Tomlinson (1969). It followed that the calcareous plate was potentially homologous with the rostral plate of scalpellomorphs, a misconception rectified by Grygier and Newman (1985). Kolbasov now suggests the plate is basal rather than rostral in position, and is ‘‘... homologous to the calcareous base of some thoracicans.’’ However, not only has molecular genetics (Pérez-Losada et al., 2008) shown the acrothoracicans are separated from the thoracicans by the plate-less Rhizocephala, a calcareous basis is largely confined to the higher balanomorphs. Thus, it would appear the calcareous plate of some acrothoracicans is convergent with those in thoracicans. Yet, it tends to occur in the primitive members (Grygier and Newman, 1984). JOURNAL OF CRUSTACEAN BIOLOGY, 31(1): 209–211, 2011

The Grooming Behaviors of the Hawaiian River Shrimp, Macrobrachium grandimanus

Abstract: The grooming behaviors of the Hawaiian river shrimp, Macrobrachium grandimanus (Caridea: Palaemonidae), are examined in this study. This species has a dense aggregation of setae (termed the “setal patch”) located on the major second cheliped. The function of this setal patch is unknown but hypothesized to be utilized in grooming activities. The grooming behaviors were documented in terms of appendages used to groom, groomed body areas, type of grooming behavior (pick, brush, or scrape) and a time budget for grooming. The most frequently used grooming appendages are the third maxillipeds and first pereiopods, while the most frequently groomed body region is the antennules. The most frequently used grooming behavior is a scraping action; the body region groomed for the longest amount of time is the branchiostegite (gill cover) region where the gill chamber is located. The time budget for grooming was 24.7%, which suggests approximately six hours per day are dedicated to grooming. Multiple statistic...

Nuclear 18S rDNA As A Species-Level Molecular Marker for Leucothoidae (Amphipoda)

Abstract: Leucothoid amphipods were investigated using nuclear 18S ribosomal DNA sequences. Analysis of sequences from eight species in two genera supported the current morphological species designations and the separation of the family into two clades. Additionally, an anamorph-leucomorph connection has been confirmed with molecular sequence data that demonstrated both morphologies conclusively belonged to the same species, Anamixis vanga Thomas, 1997. Analyses suggest that morphology is reflecting the genetic evolutionary history of the family. Levels of sequence divergence are compared for 18S rDNA and COI mitochondrial DNA in Leucothoidae.

Egg Production of the Commercially Exploited Deepwater Shrimp, Heterocarpus Vicarius (Decapoda: Pandalidae), Pacific Costa Rica

Abstract: The pandalid Heterocarpus vicarius is a deepwater shrimp, commercially exploited along the Pacific coast of Costa Rica and neighboring countries. The constant decrease of commercial landings in recent years has provoked an increasing concern about the sustainability of this deepwater resource. To facilitate an adequate management of H. vicarius, we examined 240 ovigerous females collected between 2004 and 2007. Females ranged in size between 29.4 and 45.4 mm carapace length and carried on average 15,008 newly-extruded eggs. To our best knowledge, the maximum of 33,549 eggs for H. vicarius is the highest number so far reported for any pandalid species. During embryogenesis, the average number of eggs decreased by 46.9%, while the average egg volume increased by 53.3%. Average egg volumes were statistically different between early (Stage I: 0.045 mm3) and late (Stage III: 0.069 mm3) development. The egg mass volume comprised on average 17.8% of the dry weight of ovigerous females (Stage I). Althoug...

New Eocene Crayfish from the McAbee Beds in British Columbia: First Record of Parastacoidea in the Northern Hemisphere

Abstract: Description of a new genus and species of crayfish from the Eocene McAbee beds in southern British Columbia, Canada, marks the first occurrence of Parastacoidea Huxley, 1879, in the Northern Hemisphere. The superfamily is widely distributed in modern aquatic environments in the Southern Hemisphere, except in Africa and Antarctica, as well as in Australia, New Zealand, and South America in the fossil record. The occurrence of a single species in the Eocene of North America suggests a Cretaceous or Paleogene dispersal from the Southern Hemisphere through eastern Asia. Remarkable preservation of the specimens reveals traces of muscles, the endophragmal skeleton, and the intestinal tract.

Responses to Light In Two Eyeless Cave Dwelling Amphipods (Niphargus ictus and Niphargus frasassianus)

Abstract: Two amphipod species, Niphargus ictus and N. frasassianus, which are endemic to Frasassi Caves, Italy, possess morphological features typical of most troglobitic species. Most notably they lack eyes. Although cave waters flow directly into the adjoining Sentino River and N. frasassianus is found within two meters of the resurgence, neither species is present at or further outside the mouth of the cave, which raises the question of how they avoid leaving the cave. It was hypothesized that these animals might be able to detect light, and could use light cues to remain inside the cave. Individuals of both species exhibited greater activity levels in the presence of bright vs. low light levels. Neither species exhibited the dorsal light reflex, but both showed weak negative phototaxis when exposed to bright light directed at them from above and below. N. frasassianus, tested in an apparatus that permitted them to travel freely between bright or low lighted areas, demonstrated negative phototaxis. The...