We describe an intersex specimen of the Marmorkrebs, the only obligate parthenogenetic freshwater crayfish with an all-female population. The individual was a fully functional female which possessed male-like first pleopods. Nevertheless, it reproduced successfully and the offspring were normally developed parthenogenetic females, lacking any trace of male traits. The general rarity of aberrant sexual traits in freshwater crayfishes, in particular in Procambarus, is discussed. We suggest that a dysfunction of the sex determining system, which controls the anlagen of the androgenic glands during development, caused the partial male-like phenotype of this Marmorkrebs specimen. The application of this organism for investigations of sex determination and differentiation is recommended.

The current knowledge of the precise extension and location of the androgenic gland (AG) in the genera Litopenaeus and Rimapenaeus is partial. Therefore, we analyzed the complete structure of the AG and cellular cord associated with the reproductive system of Litopenaeus setiferus, L. occidentalis, L. stylirostris, and Rimapenaeus byrdi at the stereoscopic microscopy and histological level. Our observations clearly show that the adult male reproductive system has a cellular cord that runs along the entire vas deferens. This cord is a blood vessel that runs along the ampoule, the descending and the ascending medial vas deferens. Terminal ampoules of the four species investigated have a gland-like tissue associated with the blood vessel that is attached to the external surface near to the chamber containing sperm; this structure was identified as the AG and is formed by a homogeneous mass of cells characterized by a small size (7 µm), a cytoplasm with discrete cell boundaries, and an oval nucleus (4 µm). The blood vessel is surrounded by massive layers of adipose tissue at the distal region of the ascending medial vas deferens, near to the large lumen that contains sperm. This tissue has large cells (25–40 µm), with eosinophilic cytoplasms, and small nuclei (4–5 µm) in L. setiferus; L. stylirostris and L. occidentalis also show a cellular structure at the same location, identified as white adipose tissue. This anatomical description further improves the current knowledge of the general organization of the male reproductive system of Litopenaeus and Rimapenaeus.

Marine isopods of the genus Idotea [I. balthica (Pallas, 1772), I. chelipes (Pallas, 1766), and I. granulosa Rathke, 1843] are common meso-grazers that enter deep into the Baltic Sea and here appear to live at their physiological limit, determined by salinity and temperature tolerance. We review available data on distribution and community ecology to assess the functional role of Idotea in the Baltic Sea and how global change may affect essential ecological interactions. Data from the last 150 years suggest an on-going shift southward for I. chelipes and I. granulosa that may be caused by a changing climate. Several studies report local extinctions and mass abundances, which may be caused by a changing food web from over-fishing and eutrophication. The three species of Idotea have clear habitat segregation in the Baltic Sea, where salinity, temperature and vegetation are the main dimensions. Idotea spp. have a central role as grazers and in communities dominated by the perennial macrophytes Fucus spp. and Zostera marina and attain impressive feeding rates on a range of epiphytes/filamentous algae (top-down effect). Idotea can have both a direct negative grazing effect on macrophytes but also an indirect positive effect by removing epiphytes. The relative role of nutritional value and chemical defence for food preference is yet unclear for Idotea. Baltic idoteids are also important prey for several fish (bottom-up effect) and fish predation may have increased following over-fishing of piscivorous fish. It is concluded that Idotea is a key taxon in the Baltic Sea food web, where guilds often contain few dominant species. Changes in population dynamics of Idotea, as a function of human generated global change, may have large-scale consequences for ecosystem functions in a future Baltic Sea, e.g. the extent of vegetation cover in the coastal zone.

The sexual system of the shrimp Parhippolyte misticia (Clark, 1989), inhabiting the rocky subtidal at Okinawa, Japan and Kimbe Bay, Papua New Guinea, was examined. Dissections suggested that the population consisted of male phase (MP) and functional simultaneous euhermaphrodite (EH) individuals. MPs have cincinulli and appendices masculinae on the first and second pair of pleopods, respectively, gonopores located at the coxae of the third pair of walking legs, and ovotestes with a well-developed male portion containing sperm, but an undeveloped female portion. EHs lacked appendices masculinae and cincinulli. However, they have male gonopores and ovotestes with well-developed ovaries containing mature oöcytes and testes with sperm. When EHs were maintained in pairs, both shrimp molted and spawned eggs which attached below the pleon and developed as embryos, demonstrating that EHs can reproduce as males and inseminate other EHs acting as females. These results demonstrate that P. misticia is a protandric simultaneous hermaphrodite, as reported before for other shrimp of the genera Lysmata and Exhippolysmata. Also, these results suggest that protandric simultaneous hermaphroditism might have evolved more than once independently in shrimp from the diverse and species-rich Infraorder Caridea. Future research aimed at disentangling the phylogenetic relationship of Parhippolyte, Lysmata, Exhippolysmata and other closely related genera (Calliasmata, Lysmatella, Barbouria) and describing the sociobiology of additional representatives from the genera above is needed to understand the evolutionary history of sexual systems in caridean shrimp.

Ontogenetic change in body density and shape of phyllosoma larvae was examined for the Japanese spiny lobster Panulirus japonicus (von Siebold, 1824) using laboratory-cultured specimens from hatching to the final phyllosoma stage before metamorphosing to the puerulus stage. Phyllosomas have a unique body form that is leaf-like and dorso-ventrally compressed with several appendages, and a long planktotrophic life in the ocean. Ontogenetic change was not found in the larval body density, and the mean density (1.097 g cm^-3) was greater than the seawater density (1.024 g cm^-3), indicating that they must employ strategies to control their buoyancy. The body shape of the phyllosomas changed during development into the puerulus stage where pleopods on the pleon and the pereiopods function as swimming organs and walking legs, respectively. The pleon rapidly developed after the mid-stage VI phyllosoma (10.6 mm body length (BL)). The thoracic pereiopods, including the third maxilliped, that function as swimming organs during the phyllosoma stage, generally showed negative allometric growth, indicating that the potential swimming ability decreased with development. Aspect ratios, defined as (long-axis length)² /(area), of the cephalic shield and the thorax increased from stage I(1.5 mm BL) and tended to be stable from stage V (5.9 mm BL). Relatively reduced swimming ability might be recovered with the aid of the cephalic shield and the thorax, which have higher aspect ratios that may generate a larger lift force with less power.

Raninoida, also known as “frog crabs,” is a clade of extant true crabs (Brachyura) characterized by a fusiform carapace (raninid-type), narrow thoracic sternum, pleon partially exposed dorsally, and paddle-like limbs, all of which are well suited to their cryptic burrowing lifestyle. However, the most basal raninoids from the Cretaceous were morphologically different, with ornamented carapaces that were wider than long (necrocarcinid-type), a broader thoracic sternum, and the pleon fitting between the legs assisted by pleonal locking mechanisms. During Albian times (∼112 to 99.6 Ma.) both body plans flourished worldwide. In contrast, pre-Albian (older than ∼112 Ma.) fusiform families have not yet been reported. The discovery of Notopocorystes kerri n. sp., a fusiform crab from the upper Aptian (∼115 Ma.) of Colombia, South America, and the re-examination of Planocarcinus olssoni (Rathbun, 1937) n. comb., a necrocarcinid-like crab from the same age and locality, extend the record of the two body plans back into the Aptian of the equatorial Neotropics. Notopocorystes kerri is the oldest fusiform raninoid known to date, revealing that the morphological innovation of a fusiform carapace was already evolved in Raninoida before the rapid radiation experienced during Albian times. Our findings are suggestive of a still unresolved Palaeocorystidae, containing the rootstock for the post-Aptian Raninidae/Symethidae clade, with the most basal palaeocorystids lying in proximity to, and possibly derived from, a necrocarcinid-like ancestor.

Differences in tissue specific fractionation have important practical implications for ecological studies. We have examined isotopic fractionation δ¹³C and δ¹⁵N among four different tissues in the spiny lobster Palinurus elephas (Fabricius, 1787). Two sets of individuals differing on diet-quality (captive animals with monospecific diet and wild lobsters) were studied to determine the best tissue to be used as a proxy of feeding ecology: muscles of the pleon, muscles of the legs, telson, and hemolymph. We observed significant differences in isotopic fractionation δ¹³C and δ¹⁵N among the analyzed tissues. In both captive and wild specimens leg muscle was the most δ¹⁵N enriched tissue, followed by pleonal muscle, hemolymph, and telson. For δ¹³C the sequence in isotopic discrimination was pleonal muscle > leg muscle > hemolymph ≈ telson. Lower intra-individual variability was observed in captives compared to wild individuals, as expected from a constant diet. Finally, we conclude that leg muscle is the best tissue for studying P. elephas trophism since it presents the lowest variability at isotopic level for N. The sampling of leg muscle, a regenerating tissue, is therefore suitable as a non lethal technique for trophic assessment at lobsters.

We tested the utility of a 230 base pair intron fragment of the highly conserved nuclear gene Elongation Factor 1-alpha (EF1-α) as a proper marker to reconstruct the phylogeography of the marine amphipod Pontogammarus maeoticus (Sowinsky, 1894) from the Caspian and Black Seas. As a prerequisite for further analysis, we confirmed by Southern blot analysis that EF1-α is encoded at a single locus in P. maeoticus. We included 15 populations and 60 individuals in the study. Both the phylogeny of the 27 unique alleles found and population genetic analyses revealed a significant differentiation between populations from the aforementioned sea basins. Our results are in remarkable agreement with recent studies on a variety of species from the same area, which invariably support a major phylogeographic break between the Caspian and Black Seas. We thus conclude that our EF1-α intron is an informative marker for phylogeographic studies in amphipods at the shallow population level.

Overharvesting of the land crab Cardisoma guanhumi (Latreille, 1828) has occurred in some locations including Puerto Rico. We placed passive integrated transponder (PIT) tags in this crab, C. guanhumi, to estimate a population on the southern coast of Vieques island, Puerto Rico. We were able to recapture marked animals approximately 1 year after tagging. We estimated the population of C. guanhumi on the southern central coast Vieques to be approximately 29 000 individuals. The recapture locations of individuals averaged 136 m (SE ± 55.1) from their point of initial capture. This is remarkable because these crabs are reported to move annually inland up to several kilometers for mating. Either some C. guanhumi do not move during mating season, or they return to the same location they left. The carapace size of captured C. guanhumi suggests hunting was not greatly pressuring populations at the time of this study. These findings may help natural resource managers implement a conservation plan that will allow sustainable harvest of this population.

Microsatellites were used to determine paternity of Metacarcinus magister (Dana 1852), the Dungeness crab, embryos produced through controlled laboratory matings. Additionally, spermathecal and bursal sperm from mated females were genotyped to elucidate patterns of sperm storage and use. Spermathecal and bursal contents and egg clutches from female M. magister of unknown mating history were similarly analyzed. Genotyping of embryos revealed that bursal sperm are not used in fertilization. Multiple paternity was discovered in clutches from controlled matings and in 40% of clutches carried by crabs of unknown mating history. Males achieve last male sperm precedence through stratification of ejaculates within the spermatheca, but males may actually reduce their reproductive success by depositing too much sperm in the spermatheca. Stratification occasionally fails if the fresh ejaculate is large in volume, or when large volumes of stored sperm are present in the spermatheca, resulting in displacement of stored sperm towards the oviduct and multiple paternity within clutches. Sperm competition is interannual between the single primary male mate at each molt (adult females molt and mate once a year and sperm is retained across molts), and clutches fertilized with sperm as old as 2.5 years can develop to maturity. Female crabs may copulate for reasons other than to gain sperm for fertilization. Despite possessing internal sperm storage organs where oöcytes first encounter sperm, the act of fertilization in M. magister may occur externally.

Based on the superposition of 19 individual tracks of American species of the freshwater copepod genus Eucyclops, two generalized tracks were found. The Western Amazonian track (southern Peru, eastern Brazil, and central Colombia) corresponding to the Amazonian subregion and the South American Transition Zone, and the Mesoamerican-Northwestern South American track (central Colombia, Central America, and northeastern Mexico) corresponding to the Neotropical region, the Mexican Transition Zone, and the Nearctic region. One node was found in Colombia, an area where both generalized tracks intersect. The distributional patterns of Eucyclops apparently involve two cenocrons: one Holarctic, and another Paleotropical. The Western Amazonian generalized track can be correlated with the existence of rivers that function either as barriers or dispersal passageways, the uplift of the Andes, and the presence of the Miocene “Pebas lake/wetland system.” The Mesoamerican-Northwestern South American generalized track can be associated with climate changes resulting from the uplift of North American mountain ranges, the presence of marine barriers (Isthmus of Tehuantepec and Panama) and the uplift of mountains in southern Mexico and Central America. The closing of the marine barrier represented by the Isthmus of Panama seems to have been a key event in the northward and southward dispersal of Eucyclops in the Americas.

The Australian stygofauna comprises a unique and diverse assemblage of invertebrates, of which the amphipod crustaceans are a dominant but poorly described element. Recent exploration of the Western Australian stygofauna, in particular the Yilgarn region of central Western Australia, has shown evidence of great species diversity, with numerous individual calcrete aquifers found to contain unique assemblages of invertebrate species. A recent fine-scale biodiversity initiative, using COI barcoding, of a single calcrete aquifer (Sturt Meadows) in the Yilgarn region reported the presence of three divergent and morphologically cryptic stygobitic lineages of amphipods from Chiltoniidae, which represent undescribed taxa. This paper details the subsequent systematic analysis of these COI lineages and presents a broader phylogeny and detailed morphological analyses of the lineages. The report of cryptic species was not supported upon morphological examination and three new species from three new genera (Scutachiltonia n. gen., Stygochiltonia n. gen., and Yilgarniella n. gen.) are described from the Sturt Meadows calcrete aquifer. The three genera do not form a monophyletic group and are instead believed to have evolved from separate colonisation events from distinct ancestors rather than from speciation events within the aquifer. This work contributes to a broader research initiative, documenting the presence of a rich subterranean invertebrate fauna in the Yilgarn region.

A new genus and species of deep-sea shrimp, Maximiliaeus odoceros, was collected from the Solomon Sea off Papua New Guinea. This penaeoid has a characteristic carapace; bearing large teeth on its entire dorsal border, and the presence of three parallel carinae that nearly run the entire length of the lateral carapace surface. Phylogenetic analysis using PEPCK and NaK sequences confirmed that this new taxon belongs to Solenoceridae.

The reliability of population dynamics and stock assessment models hinges on accurate life-history information. Mark-recapture studies represent a commonly used technique to investigate crustacean growth, mortality, and migrations. We evaluated tagging by coded microwire tags for the American lobster, Homarus americanus H. Milne Edwards, 1837, in a controlled study to determine tag retention and any influence on growth increment, intermolt duration, or survival. Microwire tags were injected into the propodus of the second right walking leg and two size classes (12–19.6 and 19.7–30 mm carapace length [CL]) were tested by two individual taggers. Overall tag retention was 96%. Tag retention after first ecdysis was 95% for the 12–19.6 mm CL and 92.5% for the 19.7–30 mm CL size class. There was no significant difference in tag retention between taggers, growth between tagged and untagged lobsters, or intermolt duration between tagged and untagged lobsters (P > 0.05 for all tests). Tag-induced mortality did not occur. These results support the further use of coded microwire tags to explore life-history variables for juvenile lobsters in the wild.