Molecular and morphological differentiation between two Miocene-divergent lineages of Amazonian shrimps,with the description of a new species (Decapoda,Palaemonidae, Palaemon)

Palaemon carteri (Gordon, 1935) and Palaemon ivonicus (Holthuis, 1950) are morphologically similar species of South American freshwater shrimps. Past studies have questioned the taxonomic status of both species, which are supposed to have partially sympatric geographic distributions in the Amazon basin. We analyzed a 550 bp fragment of the mitochondrial 16S rRNA gene from these Amazonian Palaemon species as well as from 11 palaemonids as the outgroup. Additionally, we checked diagnostic characters of the genus and family as well as other morphological characters that have been little explored before. Palaemon carteri and Palaemon ivonicus are allocated in two sister lineages, with wide genetic divergence and little morphological differentiation. The divergence time between these lineages was estimated as approximately 10 million years ago. Both molecular and morphological data support the taxonomic validity of both Palaemon carteri and Palaemon ivonicus, refuting the hypothesis of synonymy. In addition, a new species, Palaemon yuna sp. n., closely related to Palaemon ivonicus, is described. Our findings indicate that these species can be differentiated using the projection of the anterolateral margin and anterolateral spine of the first antennular segment, shape of the rostrum, and relative size of the appendix masculina.     

An integrative approach to the evolution of shrimps of the genus Palaemon (Decapoda,Palaemonidae)

Shrimps of the genus Palaemon Weber, 1795 comprise of 86 species with a wide morphological and ecological variability along the tropical and temperate regions. Studies based on molecular data have indicated that despite a recent taxonomic rearrangement, it may remain not monophyletic. On the other hand, cladistic, morphological analyses have suggested the presence of synapomorphies, implying a natural status for the genus. In this work, a broad taxonomic and molecular sampling is applied to verify whether Palaemon is a monophyletic taxon and, based on the recovered phylogeny, identify geographical and morphological patterns related to the lineages. Partial sequences of 16S rRNA, histone H3 and 18S rRNA from 60 species of Palaemon and 15 species from other genera of Palaemonidae were analysed. In addition, previously used characters as well as novel diagnostic characters were scrutinized. The present phylogeny indicates that the species of Palaemon fall into three distinct lineages and that the colonization of America and Europe likely occurred multiple times. Morphological characters allow for the identification of at least four monophyletic groups in Palaemon; two of which are monospecific at the moment. Based on the present results, it may become necessary to establish two new genera (to accommodate Palaemon concinnus and Palaemon mercedae, respectively), as well as re‐erect the genus Alaocaris Holthuis, 1949 for Palaemon antrorum, potentially including a further six American species.     

Life history traits of two dwarf cichlids species in the white waters of the Amazonian floodplain

The reproductive parameters are among the most important life history aspects of fishes influenced by environmental variation. During recent years, the main life history strategies of Amazonian fish species were defined mostly by a set of reproductive parameters. In the present work, we sought to describe important life history parameters, in particular on reproductive characteristics of Apistogramma agassizii and Apistogramma bitaeniata, found in floodplain lakes of the Brazilian Amazonia. The species presented a positive sexual dimorphism, and males were significantly bigger than females. For both sexes, four developmental phase of gonad maturation were detected, and based on those it was possible to identify mature, reproductive specimens throughout the entire period of the study. From the ovaries of mature females, fecundity and spawning type were determined. Low fecundity, short spawning periods, possibly separated only by few months, and total spawning are all good indications that A. agassizii and A. bitaeniata evolved an opportunistic strategy in their life history.     

Molecular phylogeny and diversity of penaeid shrimps (Crustacea: Decapoda) from South-East Asian waters

The decapod family Penaeidae comprises most of the economically important marine shrimp species. Its members are widespread throughout the world, with its highest species diversity centred in the Indo-West Pacific region. Despite this importance, their taxonomy, classification and phylogeny are not yet settled due in part to incongruence among hypotheses proposed from molecular versus morphological studies. In this study, using a thorough taxonomic sampling of especially the South-East Asian species, we aim to (a) utilize a reconstructed phylogeny to test the monophyly of the Penaeidae and its currently recognized genera and (b) explore its species diversity in South-East Asian waters. To infer the phylogeny, a combined gene data set (including 109 ingroup and six outgroup taxa) of mitochondrial genes, COI and 16S rRNA, and two nuclear genes, NaK and PEPCK, was utilized. To explore its diversity, another data set that included 371 COI gene sequences (231 newly generated and 140 retrieved from public sources) was compiled and subsequently analysed with two different tools (ABGD and bPTP) for species delimitation. Other than supporting the non-monophyly of the Penaeidae with the Sicyoniidae nested within the penaeid tribe Trachypenaeini, the genera Penaeus, Mierspenaeopsis and Parapenaeopsis were also revealed to be polyphyletic. Our species delimitation analysis inferred that 94 putative species actually existed within the 71 morphospecies reviewed, indicating an underestimated biodiversity in this family and the potential presence of new species within the following morphospecies: Kishinouyepenaeopsis cornuta, K. incisa, Mierspenaeopsis sculptilis, M hardwicki, Parapenaeopsis coromandelica and Penaeus monodon.     

Lipid composition and utilization in developing eggs of two tropical marine caridean shrimps (Decapoda: Caridea: Alpheidae, Palaemonidae)

Changes in biomass and lipid biochemistry during egg development were studied in the tropical shrimps, Alpheus saxidomus and Palaemonetes schmitti, from Pacific Costa Rica. Freshly-laid eggs of P. schmitti were substantially smaller than those of A. saxidomus; dry mass decreased during embryogenesis in the former species but remained almost constant in the latter one. Water content of eggs close to hatching were similar among both species (roughly 75%). Newly-produced eggs of the two species contained ≈20% fatty acids per egg dry mass; a comparison with data concerning decapods inhabiting tropical and temperate waters revealed that eggs produced by shrimps inhabiting tropical waters tend to have a higher lipid egg content per dry mass than those from temperate regions. Major lipid classes in the eggs of both species were phospholipids and triacylglycerols which increased and decreased during the incubation period, respectively. The predominant fatty acids of P. schmitti eggs were 16:0, 20:5(n-3) and 22:6(n-3) whereas eggs of A. saxidomus showed high amounts of 16:0, 20:5(n-3) and 16:1(n-7), and remarkably low values of 22:6(n-3) fatty acid. Lipid utilization was more pronounced in P. schmitti; in A. saxidomus, eggs close to hatching still contained 70% of the initially deposited fatty acid content which may indicate an enhanced independence of the newly-hatched larvae on external energy resources. The observed differences may partially be related to different habitat preferences, however, the role of adaptation and phylogeny as determinants of egg lipid biochemistry in caridean shrimps remains to be clarified.     

The distribution of freshwater shrimps (Atyidae and Palaemonidae) in Jamaica

The distribution of freshwater shrimps in Jamaica is presented. Atya innocous, Atya lanipes, Atya scabra, Micratya poeyi and Macrobrachium heterochirus were found only in the high-gradient streams characteristic of eastern and north-eastern parishes. Macrobrachium acanthurus, Jonga serrei , and Potimirim mexicana were found only in the low-gradient streams characteristic of western and southwestern parishes. Macrobrachium faustinum, Macrobrachium carcinus , and Xiphocaris elongata were distributed throughout Jamaica. Oxygen, temperature, and current speed were the physical features of the streams most likely influencing this distribution. It was observed that species in high-gradient streams had larvae which required high salinity for development, and those in low-gradient streams had larvae with low salinity requirements. It is argued that larval salinity preferences during the marine planktonic stage of the life history could allow larvae to select an appropriate river prior to its being invaded by juveniles.     

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     

A re-description of Macrobrachium handschini (Roux, 1933) (Crustacea: Decapoda: Palaemonidae)

Diversity, distribution, seasonal changes in density and relative abundance of Ephemeroptera nymphs were studied in five stations on three streams in and around Shillong, Meghalaya state, North-eastern India. Seventeen species belonging to eight genera and five families were recorded. Diversity (Shannon's index) was governed by the heterogeneity of the substratum which in turn was influenced by catchment disturbances (quarrying, logging, and entry of sewage). Seasonal changes in density were governed by the spate-frequency regime of the streams. Relative abundance showed dominance of one or two species at impacted stations, while in less disturbed ones, a more equitable distribution of species was observed.     

Critical thermal maxima and minima of Macrobrachium rosenbergii (Decapoda: Palaemonidae)

1. Critical thermal maxima (CTMax) and minima (CTMin) were determined for postlarvae and juveniles of Macrobrachium rosenbergii acclimated at 20, 23, 26, 29 and 32±1°C. 2. At each acclimation temperature the CTMax and CTMin for postlarvae were 37.3, 38.3, 39.0, 41.0, 41.6°C and 10.0, 11.0, 13.0, 14.8, 16.8°C respectively and for juveniles 36.5, 38.4, 39.2, 41.5, 42.0 and 10.5, 11.3, 13.3, 14.6, 16.4°C respectively. 3. We found no indication of significant differences (P>0.05) in the CTMax and CTMin of the prawn postlarvae and juveniles. 4. The zone of thermal tolerance base on the CTMax and CTMin boundaries for postlarvae was 821.2°C² and 816.9°C² for juveniles, showing a high degree of eurythermality. To cultivate this species it should be done in no less than 16°C (CTMin) and below 42°C.     

A Revision of Australian River Prawns, Macrobrachium (Crustacea: Decapoda: Palaemonidae)

A taxonomic revision of Australian Macrobrachium identified three species new to the Australian fauna – two undescribed species and one new record, viz. M. auratumsp. nov., M. koombooloombasp. nov., and M. mammillodactylus(Thallwitz, 1892). Eight taxa previously described by Riek (1951) are recognised as new junior subjective synonyms, viz. M. adscitum adscitum, M. atactum atactum, M. atactum ischnomorphum, M. atactum sobrinum, M. australiense crassum, M. australiense cristatum, M. australiense eupharum of M. australienseHolthuis, 1950, and M. glypticumof M. handschiniRoux, 1933. Apart from an erroneous type locality for a junior subjective synonym, there were no records to confirm the presence of M. australe(Guérin-Méneville, 1838) on the Australian continent. In total, 13 species of Macrobrachiumare recorded from the Australian continent. Keys to male developmental stages and Australian species are provided. A revised diagnosis is given for the genus. A list of 31 atypical species which do not appear to be based on fully developed males or which require re-evaluation of their generic status is provided. Terminology applied to spines and setae is revised.     

Life history tactics of southern velvet shrimp Metapenaeopsis palmensis (Crustacea,Decapoda) in the waters off southwestern Taiwan

The southern velvet shrimp, Metapenaeopsis palmensis, a small, tropical r-strategist shrimp, was investigated to test whether its life history tactics are similar to those of penaeid shrimps. In total, 7,832 shrimps were collected in southwestern Taiwan from April 2002 to August 2011. For the first time, we have identified the shrimp as a multiple spawner. This species has a size-segregated distribution, with the newly recruited early juveniles [<6.00 mm carapace length (CL)] living offshore (water depth = 30 m) and the subadults and mature spawning adults (CL ≥9.39 mm) living inshore (water depth = 15–20 m). They spawn from February to June before the rainy season when the water temperature exceeds 25°C. Only the larvae hatched in the late spawning season will successfully recruit in the dry season in September–November when the bottom water salinity is higher than 33.5 psu. The life history tactics of this species are different from those found by various previous studies on penaeid shrimps.     

Embryonic development of the Caridean prawn Macrobrachium mammillodactylus (Crustacea: Decapoda: Palaemonidae)

The freshwater knob-tooth prawn Macrobrachium mammillodactylus is a commercially exploited species in the Philippines. To study the biology of this species, broodstock from the wild was collected, transported to the laboratory and kept in pairs in indoor polyethylene tanks for breeding. Eggs from berried females were sampled to follow the stages of embryonic development until hatching to zoea larva. It took 18.0?±?2.1?days for the eggs to hatch at ambient water temperature between 25 and 28?°C. The morphological landmarks of development at the different stages (pre-cleavage, cleavage, blastula, pre-nauplius, post-nauplius and pre-hatching) of the live embryos are described. Incremental percentage staging was adopted from 0% at fertilization to 100% at hatching and were matched with corresponding morphological development. Egg volume increased significantly toward the mid-to-later stages of development. The eye index also showed a significant increase as the egg developed. The colour of the egg mass changed from light olive green to grey as the eggs progressed in development. The general pattern of development was comparable to other members of the genus Macrobrachium.     

Effect of salinity on the embryonic development of Macrobrachium acanthurus (Decapoda: Palaemonidae)

The effect of salinity level on the embryonic development of Macrobrachium acanthurus was analyzed under laboratory conditions, considering characteristics of the egg (size, volume, and water content) and of the embryo (eye index). The experimental design was completely randomized, with five repetitions (ovigerous females) per treatment (0, 10, 17 and 20 ppt). During embryonic development, two eggs per female were taken daily for analyses of size, volume, water content, and eye index. Our results showed that salinity of 20 ppt leads to death and/or abortion of the embryo in all females. The size, volume and water content of eggs increased according to embryonic development, providing space in the egg for formation and organization of embryo. Salinity affected these egg characteristics, causing water loss to the hypertonic medium. Neither the duration of embryonic development nor embryo formation were affected by saltwater content. The results of the present study indicate that ovigerous females of M. acanthurus can survive in freshwater rivers as well as in low-salinity environments during incubation period and the successful larval development is not likely to rely on female migrating to estuaries. Larvae can easily be incubated in freshwater and complete development at higher salinities after hatch.     

Molecular and morphological phylogeny of hooded shrimps, genera Betaeus and Betaeopsis (Decapoda, Alpheidae): testing the center of origin biogeographic model and evolution of life history traits

The phylogenetic relationships of the alpheid shrimp genera Betaeus (Dana, 1852) (15 species) and Betaeopsis (Yaldwyn, 1971) (three species), collectively known as hooded shrimps, are analyzed with morphological, molecular (16S and H3) and combined "total evidence" (morphology+DNA) datasets. The tree topology resulting from morphological and combined analyses places Betaeus jucundus as sister to all the remaining species of Betaeus and Betaeopsis, rendering Betaeus paraphyletic. On the other hand, Betaeopsis is recovered as monophyletic. Betaeus australis is positioned as sister to the remaining species of Betaeus s. str. (excluding B. jucundus), which is composed of three well-supported and resolved clades. Mapping of biogeographic traits on the combined tree suggests at least two possible historic scenarios. In the first scenario, the North-East Pacific harboring the highest diversity of hooded shrimps (seven species of Betaeus), acted as the "center of origin", where species appeared, matured and eventually migrated toward peripheral regions. In the second scenario, Betaeus+Betaeopsis originated in the southern Indo-West Pacific and subsequently colonized the North-East Pacific, where a major radiation involving dispersal/vicariance events took place. The mapping of life history traits (symbiosis vs. free living and gregariousness vs. single/pair living) in the combined tree suggests (1) that different types of symbioses with dissimilar host organisms (sea urchins, abalones, other decapods, spoon worms) evolved independently more than once in the group (in B. jucundus and in various lineages of Betaeus s. str.), and (2) that gregariousness was ancestral in the Betaeus s. str. -Betaeopsis clade and later shifted toward single/pair living in several lineages.     

Phylogeny of penaeoid shrimps (Decapoda: Penaeoidea) inferred from nuclear protein-coding genes

Penaeoidea is a diverse group of economically important marine shrimps. Attention to the evolutionary history of the penaeoids has been raised since studies using mitochondrial DNA markers and sperm ultrastructure contradict classification of the penaeoid families based on morphology and hence challenge the long standing taxonomy of this superfamily. In this study, DNA sequences of two nuclear protein-coding genes, phosphoenolpyruvate carboxykinase and sodium–potassium ATPase α-subunit, were determined from 37 penaeoid genera to reconstruct the evolutionary relationships and to estimate divergence ages of the penaeoid shrimps. Phylogenetic analyses using maximum likelihood and Bayesian approaches strongly support the monophyly of Solenoceridae, Aristeidae and Benthesicymidae, but find Sicyoniidae nested within Penaeidae, making this family paraphyletic. Penaeoidea comprises two lineages: the former three families in one while the latter two in another. The diversification of these lineages may be related to bathymetry. The penaeid-like lineage diversified in the Triassic, earlier than the aristeid-like lineage with an origin in the Jurassic. Taxonomic revisions within Penaeoidea are also proposed for further investigation. Due to the paraphyly of Penaeidae and the high genetic divergence among the three penaeid tribes of Burkenroad [Burkenroad, M.D., 1983. Natural classification of Dendrobranchiata, with a key to recent genera. In: Schram, F.R. (Ed.), Crustacean Issues I. Crustacean Phylogeny. A.A. Balkema, Rotterdam, pp. 279–290], these tribes should be treated as having the same taxonomic rank as Sicyoniidae, while the family ranking of Benthesicymidae has to be re-considered owing to the low genetic divergence between the benthesicymids and the aristeids.     

Genetic structure and dispersal of Macrobrachium australiense (Decapoda: Palaemonidae) in western Queensland, Australia

SUMMARY 1. The freshwater prawn, Macrobrachium australiense (Decapoda: Palaemonidae), is an abundant species throughout the rivers of western Queensland, and it is thought to have effective dispersal capabilities. Given the very low topographical relief of the western Queensland landscape and the vast nature of episodic flooding, it was predicted that widespread dispersal in this species would occur within, and possibly between the four major catchments of the region: the Darling, Bulloo, Cooper and Diamantina. We analysed eight polymorphic allozyme systems and a fragment of the cytochrome c oxidase subunit 1 (COI) mitochondrial DNA (mtDNA) gene to determine the extent of recent and historical patterns of dispersal at nested spatial scales, within and between catchments.
2. Large and significant levels of allozyme and mtDNA differentiation were revealed among all catchments, indicating that dispersal of M. australiense does not occur across catchment boundaries, although this species is reportedly capable of overland movement. In contrast, no significant patterns of genetic differentiation were resolved between major subcatchments of the Darling and Cooper, or between sites within these subcatchments, indicating that populations of M. australiense are panmictic within catchments.
3. The MtDNA data resolved two divergent and reciprocally monophyletic clades, with the first representing the Darling catchment, and the second corresponding to the Bulloo, Cooper and Diamantina catchments. We postulate that extreme variation in historical climatic patterns and palaeohydrologic conditions played an important role in shaping the population structure of M. australiense throughout western Queensland during the Quaternary.     

Life history patterns in birds and mammals and their evolutionary interpretation

Summary It is argued that allometric principles account for most of the observed variation in the life history patterns amongst birds. To test this contention it is shown that traits such as incubation time, growth rates, age at first reproduction, lifespan, clutch weight and egg weight all scale to body weight with exponents similar to those found for analogous traits in mammals. It is then shown that most of the variation amongst bird taxa and between birds and mammals based on body weight allometry can be explained by variations in brain size, body temperature and metabolic rate, consistent with theories of growth and ageing derived from mammalian studies. Finally, it is suggested that the evidence for life histostory allometry is sufficiently strong that it argues for a more epigenetic view of life history patterns and their evolution than is generally conceded in most adaptation theories.