Global diversity of shrimps (Crustacea: Decapoda: Caridea) in freshwater

Freshwater caridean shrimps account for approximately a quarter of all described Caridea, numerically dominated by the Atyidae and Palaemonidae. With the exception of Antarctica, freshwater shrimp are present in all biogeographical regions. However, the Oriental region harbours the majority of species, whilst the Nearctic and western Palaearctic are very species-poor. Many species are important components of subsistence fisheries, whilst the Giant River Prawn forms the basis of an extensive aquaculture industry. A total of 13 species are threatened or endangered, with one species formally extinct. Guest editors: E. V. Balian, C. Lévêque, H. Segers and K. Martens Freshwater Animal Diversity Assessment     

Effects of Late-Cenozoic Glaciation on Habitat Availability in Antarctic Benthic Shrimps (Crustacea: Decapoda: Caridea)

Marine invertebrates inhabiting the high Antarctic continental shelves are challenged by disturbance of the seafloor by grounded ice, low but stable water temperatures and variable food availability in response to seasonal sea-ice cover. Though a high diversity of life has successfully adapted to such conditions, it is generally agreed that during the Last Glacial Maximum (LGM) the large-scale cover of the Southern Ocean by multi-annual sea ice and the advance of the continental ice sheets across the shelf faced life with conditions, exceeding those seen today by an order of magnitude. Conditions prevailing at the LGM may have therefore acted as a bottleneck event to both the ecology as well as genetic diversity of today''s fauna. Here, we use for the first time specific Species Distribution Models (SDMs) for marine arthropods of the Southern Ocean to assess effects of habitat contraction during the LGM on the three most common benthic caridean shrimp species that exhibit a strong depth zonation on the Antarctic continental shelf. While the shallow-water species Chorismus antarcticus and Notocrangon antarcticus were limited to a drastically reduced habitat during the LGM, the deep-water shrimp Nematocarcinus lanceopes found refuge in the Southern Ocean deep sea. The modeling results are in accordance with genetic diversity patterns available for C. antarcticus and N. lanceopes and support the hypothesis that habitat contraction at the LGM resulted in a loss of genetic diversity in shallow water benthos.     

Molecular systematics of the Kakaducarididae (Crustacea: Decapoda: Caridea)

The systematic relationships of the freshwater shrimp family, Kakaducarididae, were examined using mitochondrial and nuclear DNA sequences. Combined nuclear (18S rDNA, 28S rDNA, Histone) and mitochondrial (16S rDNA) analyses placed the kakaducaridid genera, Kakaducaris and Leptopalaemon, as a strongly supported clade within the Palaemonidae, in a close relationship with the genus Macrobrachium. Monophyly of the Australian Kakaducarididae was strongly supported by the molecular data. Estimated net divergence times between Kakaducaris and Leptopalaemon using mitochondrial 16S rDNA equate to a late Miocene/Pliocene split. Within Leptopalaemon, each locality was distinct for mitochondrial COI haplotypes, suggesting long-term isolation or recent genetic bottlenecks, a lack of contemporary gene flow amongst sites and a small Ne. Mitochondrial groupings within Leptopalaemon were largely congruent with several previously recognised morphotypes. Estimated net divergence times between L. gagadjui and the new Leptopalaemon morphotypes equate to a split in the late Pliocene/early Pleistocene. The hypothesis that the Kakaducarididae is comprised of relict species in specialised ecological niches is not supported by the molecular data, which instead suggest a relatively recent origin for the group in northern Australia, sometime in the late Miocene or Pliocene.     

The freshwater palaemonid prawns (Crustacea: Decapoda: Caridea) of Myanmar

The taxonomy of the palaemonid freshwater prawns of Myanmar is reviewed and 19 species are recorded. These belong to three genera, with 17 species of Macrobrachium, one species of Palaemonetes and one species of Leptocarpus. The identities of Palaemon spinipes birmanicus Schenkel, 1902, and Palaemon naso Kemp, 1918, are clarified with both recognised as distinct taxa. The taxonomy of several poorly known species of Macrobrachium,viz. M. villosimanus (Tiwari, 1949), M. peguense (Tiwari, 1952), M. hendersoni (De Man, 1906) and M. platyrostrum (Tiwari, 1952) is revised and discussed. Five species are reported from Myanmar for the first time, viz. Macrobrachium lamarrei (H. Milne-Edwards, 1837), M. dayanum (Henderson, 1893), M. lanchesteri (De Man, 1911), M. nipponense (De Haan, 1894), and Palaemonetes sinensis (Sollaud, 1911). One new species, Macrobrachium lanatum, which is closely allied to M. scabriculum (Heller, 1862) and M. dolichodactylus (Hilgendorf, 1879), is described and figured.     

Larvae of the deep-sea Nematocarcinidae (Crustacea: Decapoda: Caridea) from the Southern Ocean

The early larval stages of the deep-sea Nematocarcinidae, Nematocarcinus longirostris Bate, 1888, from the south-western Atlantic Ocean, and N. lanceopes Bate, 1888, from the high Antarctic Weddell Sea, were obtained from plankton catches, described and illustrated. Furthermore, field collected larvae of N. lanceopes were compared with larvae hatched and reared under constant laboratory conditions. The morphology of larvae in both species clearly indicates a planktotrophic and extended mode of larval development. This is an outstanding feature in deep-sea and especially in high-latitudinal caridean shrimp species, and the consequence of such reproductive trait for life history adaptations to both deep-sea and polar environments is discussed.This revised version was published online in November 2004 with corrections to the figure part lettering.     

Global diversity of crabs (Crustacea: Decapoda: Brachyura) in freshwater

An assessment of the global freshwater crab diversity is presented. A total of 1,476 species in 14 families are currently known from all zoogeographical regions (except Antarctica), including 1,306 species in eight exclusively freshwater families (Pseudothelphusidae, Trichodactylidae, Potamonautidae, Deckeniidae, Platythelphusidae, Potamidae, Gecarcinucidae and Parathelphusidae). Estimates of true freshwater crab diversity including likely numbers of undescribed taxa suggest that the field remains largely in a “discovery” phase. Main ideas on the origins, diversification, and phylogeny of true freshwater crabs are briefly discussed. The economic importance of freshwater crabs is also highlighted. Guest editors: E. V. Balian, C. Lévêque, H. Segers & K. Martens Freshwater Animal Diversity Assessment     

Complete mitochondrial genome of the Japanese snapping shrimp Alpheus japonicus (Crustacea: Decapoda: Caridea): Gene rearrangement and phylogeny within Caridea

The complete sequence of the mitochondrial genome of the Japanese snapping shrimp Alpheus japonicus Miers (Crustacea: Decapoda: Caridea) is presented here. A comparative analysis based on the currently available mitochondrial genomic data revealed many previously unknown characteristics of the mitochondrial genomes of caridean shrimps. The A. japonicus mitochondrial genome is 16487 bp long and contains the typical set of 37 metazoan genes. The gene arrangements in the mitochondrial genomes of four previously studied carideans (Macrobrachium rosenbergii, M. nipponense, M. lanchesteri and Halocaridina rubra) were found to be identical to the pancrustacean ground pattern; thus, it was considered that gene rearrangements probably did not occur in the suborder Caridea. In the present study, a translocation of the trnE gene involving inversion was found in Alpheus mitochondrial genomes. This phenomenon has not been reported in any other crustacean mitochondrial genome that has been studied so far; however, the translocation of one transfer RNA gene (trnP or trnT) was reported in the mitochondrial genome of Exopalaemon carinicauda. When the ratios of the nonsynonymous and synonymous substitutions rates (Ka/Ks) for the 13 protein coding genes from two Alpheus species (A. japonicus and A. distinguendus) and three Macrobrachium species (M. rosenbergii, M. nipponense, M. lanchesteri) were calculated, the Ka/Ks values for all the protein coding genes in Alpheus and Macrobrachium mitochondrial genomes were found to be less than 1 (between 0.0048 and 0.2057), indicating that a strong purification selection had occurred. The phylogenetic tree that was constructed based on the mitochondrial protein coding genes in the genomes of nine related species indicated that Palaemonidae and Alpheidae formed a monophyly and shared a statistically significant relationship, (Palaemonidae+Alpheidae)+Atyidae, at the family level.     

湖南淡水虾类两新种(十足目:匙指虾科:米虾属)

报道湖南省淡水匙指虾科米虾属两新种。窄肢米虾Caridina angustipes sp.now.与保靖米虾C.baojingensis Guo,He et Bai,1992近似,但新种额角长,上缘具15-27齿,下缘具3-6齿;雄性第一附肢内肢的内缘平直。棒肢米虾C.clavipes sp.nov.略似窄肢米虾C.angustipes,但目前雄性第一附肢内肢末端尖细,内缘刺少;雄性第二附肢雄附肢短而细,内缘仅具1刺,末端仅具4刺。正模标本保存在上海水产大学,副模标本保存在佛山科学技术学院。     

Microscopic anatomy and ultrastructure of the digestive system of three Antarctic shrimps (Crustacea: Decapoda: Caridea)

Mandibles and stomachs of three Antarctic shrimp species (Nematocarcinus lanceopes, Notocrangon antarcticus, and Chorismus antarcticus) were investigated by means of scanning electron microscopy. Transmission electron microscopy of the midgut glands was applied to find out the nutritional status of the animals, which contained a broad variety of food items in their stomachs. In contrast to the Antarctic krill, the three carideans possess a dual filter system; primary filters in the cardia and secondary filters in the pyloric chamber. Morphologically, the mandibles and stomachs of the three species vary considerably; however, their food items are similar. We conclude that stomach contents do not really reflect the different modes of life or habitat preferences of the investigated species.     

Phylogeny of Indo‐West Pacific pontoniine shrimps (Crustacea: Decapoda: Caridea) based on multilocus analysis

The phylogenetic relationships and evolutionary processes within the subfamily Pontoniinae, a speciose group of shrimps with diverse lifestyles (free living, semi‐symbiotic and symbiotic) inhabiting the coral reefs of tropical oceans, are an interesting and undeveloped subject of study. In this work, two mitochondrial ribosomal genes (12S rRNA and 16S rRNA) and two protein‐coding nuclear genes (Histone 3 and the sodium–potassium ATPase α‐subunit) were employed to reconstruct the phylogenetic relationships of 42 genera and 101 species within Pontoniinae. Compared to previous studies, ten additional genera were shown to be monophyletic groups, and the genera Dactylonia and Periclimenaeus were shown to be paraphyletic. The shallow‐water crinoid‐associated pontoniines were divided into several groups which were mostly consistent with the morphological analysis. The studied bivalve‐associated taxa exhibited ancestries that were traceable to different lineages, and two groups could be distinguished: Anchiopontonia + Conchodytes and Anchistus. The similar situation occurred in other echinoderm‐associated pontoniines. These results suggest that pontoniines sharing the same hosts may have different evolutionary origins resulting from multiple intrusions of their hosts by morphologically plastic ancestral groups.     

Male Mating Tactics in the Shrimp Palaemonetes pugio (Decapoda, Caridea): Precopulatory Mate Guarding vs. Pure Searching

The guarding of females approaching a limited period of sexual receptivity is a common mating tactic of males. In many decapod crustaceans, such as the shrimp Palaemonetes pugio , females can only copulate during a short period after a reproductive molt. It has been predicted that mate guarding by males (pre-copula) evolves in such species if sex ratios are not highly female-biased and if males can detect the molt stage of the female. The mating tactics of males were investigated in P. pugio . Time-lapse video observations were made on interactions among two males, a pre-molt female, and an inter-molt female (20 replicates). There was no evidence that males recognized a pre-molt female until 24 h before its molt. Significant numbers of male contacts with pre-molt females occurred 1 h before and after the female molt. Copulation took place within 1–3 min of the molt. No behavior commonly associated with mate guarding in decapods was observed – no clasping, agonistic behavior, or close association. It is concluded that the male's mating tactic is pure searching, wherein males haphazardly contact many females in order to find a receptive one. The high encounter rate in nature of these very mobile, aggregated shrimps is proposed as the factor responsible for the evolution of pure searching. It is hypothesized that pure searching is the male tactic of the many species of decapod shrimps with small males, sexually monomorphic cheliped weapons, and aggregated populations.     

Ageing and longevity in the Decapoda (Crustacea): A review

Ageing and longevity is a neglected field of crustacean biology. Information on longevity is available for less than 2% of the extant species of the Decapoda. Maximum ages reliably determined range from 40 days to 72 years corresponding to a life span difference of a factor of 650. The shortest-lived decapods are planktonic dendrobranchiate shrimps, and particularly long-lived species with life spans of decades are found in the Astacidea. Most decapods seem to live for 1-10 years. High geographical latitude, the deep sea and freshwater caves promote longevity. The majority of the Decapoda is indeterminately growing and presumably characterized by negligible senescence. The adults of the determinately growing decapods like some brachyuran crabs suffer from mechanical senescence and are unable to regenerate lost appendages. The decapod crustaceans have developed many effective anti-ageing mechanisms including moulting, detoxification of free radicals, removal of cellular waste, renewal of tissues by life-long stem cell activity, regeneration of appendages, detoxification of environmental pollutants and isolation of pathogens and diseased tissue areas by melanisation and encapsulation. Age related diseases including cancer are virtually unknown. The present compilation of data on longevity and senescence in decapods is the first one that covers the whole spectrum of a higher invertebrate taxon. It is hoped to provide an interesting source of information for carcinologists and biogerontologists. Further improvement of knowledge on ageing and longevity in the Decapoda would be beneficial for crustacean aquaculture, fisheries and ecological modelling. Some decapods even have good potential to become models for general ageing research.     

Grooming as a secondary behavior in the shrimp Macrobrachium rosenbergii (Crustacea,Decapoda, Caridea)

The giant freshwater prawn, Macrobrachium rosenbergii, is a large shrimp extensively used in aquaculture whose grooming behaviors were analyzed in this study. Macrobrachium rosenbergii exhibits three unique male morphotypes that differ in their behavior, morphology and physiology: small-clawed males (SM), orange-clawed males (OC) and blue-clawed males (BC). The largest and most dominant males, BC males, are predicted to have significantly different grooming behaviors compared to females and the other two male morphotypes. These BC males may be too large and bulky to efficiently groom and may dedicate more time to mating and agonistic interactions than grooming behaviors. Observations were conducted to look at the prevalence of grooming behaviors in the absence and presence of conspecifics and to determine if any differences in grooming behavior exist among the sexes and male morphotypes. Significant differences in the grooming behaviors of all individuals (females and male morphotypes) were found. BC males tended to have the highest grooming time budget (percent of time spent grooming) while SM males had a relatively low grooming time budget. The grooming behaviors of the male morphotypes differed, indicating while these males play distinct, separate roles in the social hierarchy, they also have different grooming priorities. The conditions in which Macrobrachium rosenbergii are cultured may result in increased body fouling, which may vary, depending on the grooming efficiencies and priorities of these male morphotypes. Overall, grooming behaviors were found to be a secondary behavior which only occurred when primary behaviors such as mating, feeding or fighting were not present.     

Morphology of the Midgut–Hindgut Juncture in the Ghost Shrimp Lepidophthalmus louisianensis (Schmitt) (Crustacea: Decapoda: Thalassinidea)

Abstract Unique morphological structures occur near the midgut–hindgut juncture in decapod crustaceans, and neither their fine structure nor function are well understood. In the ghost shrimp Lepidophthalmus louisianensis. structures associated with this juncture include an elongate posterior midgut caecum (PMGC) extending into the abdominal hemocoel, a massive swelling of acinar glands encasing the juncture, and a dorso-lateral valve complex involving cuticularized lumenal surfaces of the anterior hindgut. Vivisection, histological studies (LM, TEM) and paraffin-carving (SEM) have been applied to reconstruct morphology of these components and characterize constituent tissues. The lumen of the PMGC is lined by very elongate columnar cells underlain by a thin layer of circular muscle. The hemocoelic surface of the PMGC is covered by cells richly endowed with unique lamellar bodies. The acinar glands are composed of multiple rosettes of secretory cells, from which products appear to empty into the anterior extreme of the hindgut. The dorso-lateral valve complex of the hindgut consists of anterior and posterior components, differing in strength of lumenal ridging and microdentition of the cuticular lining. Unique features of these structures may relate to behavioral, feeding and metabolic adaptations in this obligate fossorial crustacean.     

云南华米虾属一新种(十足目:真虾次目:匙指虾科)

报道中国横断山区华山虾属一新种,即永胜华米虾Sinodina yongshengica sp.nov.,对其形态特征作了详细描述,并与近似种进行了比较。     

Setal morphology of the grooming appendages of Macrobrachium rosenbergii (Crustacea: Decapoda: Caridea: Palaemonidae) and review of decapod setal classification

Setae are vital in grooming activities and aiding in the removal of epibionts and sedimentary fouling from the body surfaces of decapod crustaceans. Thus, the setal structures and their arrangement on the grooming appendages and sensory structures of the commercially important shrimp, Macrobrachium rosenbergii, were examined using scanning electron microscopy. Macrobrachium rosenbergii is extensively grown in aquaculture and exhibits unique male morphological forms, termed morphotypes. The three male morphotypes are termed blue‐clawed males, orange‐clawed males, and small‐clawed or undifferentiated males and all three differ in their dominance, behavior, body morphology, and reproductive success. Seven setal types, two of which have never been described in the literature, are identified on the grooming appendages (third maxillipeds, first, second, and fifth pereopods) and antennae: simple, serrate, serrulate, spiniform, pappose, crinoid, and spinulate. The latter two setae are newly identified. Certain setal types, such as serrate and serrulate setae were located and associated with specific grooming appendages such as the first pereopods. The types of setae on the grooming appendages varied among females and male morphotypes and the novel setal types (crinoid and spinulate) were found only on two of the male morphotypes. A literature review of terminology related to the structure of setae and setal types in decapod crustaceans is offered as the usage of various terms is ambiguous and conflicting in the literature. The intention of this review is to provide future authors with a comprehensive collection of terms and images that can be used to describe various aspects of setal morphology in decapods. J. Morphol. 275:634–649, 2014. © 2014 Wiley Periodicals, Inc.     

The reproductive system of Hippolyte niezabitowskii (Decapoda, Caridea)

Data on the reproductive biology of the genus Hippolyte are available from studies of Hippolyte inermis. These findings support the idea that these species are protandric hermaphrodites, exhibiting sex reversal. However, recent studies of this and other species, such as Hippolyte obliquimanus and Hippolyte williamsi, have not reported sex reversal and suggest a gonochoric condition. In the present study, histological analyses were conducted of the ovaries, testes, oviducts, vasa deferentia and the development of the male appendage. The results of this study show that the Hippolyte niezabitowskii population from southern Spain should also be viewed as a gonochoric species. The study found no evidence of sex reversals. These conclusions are also supported by information on the structure of the population and by the results of studies of the male appendage. The population structure involves different size distributions of males and of females. Size classes 2-14 exhibit substantial overlap. No evidence of sex reversal was obtained from the study of the male appendage.