Pair Of Pereiopods Research Articles

Вариабельность морфологических и генетических признаков Macrohectopus branickii (Dyb., 1874)

Macrohectopus branickii is the only pelagic amphipod from Lake Baikal. Until now, despite the uniqueness of M. branickii, its genetic diversity at the intraspecific level, as well as its intraspecific morphological diversity, have not been studied. In this work, we present the result of a morphological analysis of intrapopulation variability of the species M. branickii from the northern basin of Lake Baikal, as well as the result of a molecular analysis based on the sequence of a fragment of the mitochondrial Nad5 gene of several individuals of this species from three basins of the lake. The material for the study was collected using a plankton net and trawl from all basins and shores of Lake Baikal at depths of 100-300 m. We measured 21 morphological characters according to the scheme previously proposed in Tikhonova’s work for sexually mature females of M. branickii living on different shores of the northern basin of Lake Baikal. The coefficient of variation of the values of all characteristics was determined. Morphological analysis revealed different degrees of variability in the studied characters for M. branickii. The most variable characters are: the length of 1 segment of the peduncle of the upper antennae; length of 4 and 5 segments of the stalk of the lower antennae; length of gnathopod propodites 2 pairs; width and length of basipodites of the third pair of pereiopods; length of the stalk, external and internal branches of the uropods of the third pair; telson width and length. Analysis of the nucleotide sequences of the Nad5 gene fragment showed their low variability. The haplotype network was reconstructed using the pegas package for the R programming language. M. branickii forms a single panmictic population, consistent with the absence of geographic and environmental barriers in the pelagic zone of the lake.

Refining southwestern Atlantic peppermint shrimp biodiversity: description of a new species ofLysmata(Decapoda: Lysmatidae) using an integrative systematic approach

AbstractCurrently, 14 of the 50 species ofLysmataare known to possess a long accessory branch with more than two articles. Historically,Lysmata intermediaandLysmata mooreiwere the only two ‘long-branch’ species inhabiting the southwestern Atlantic. Here we describe, based on morphological, molecular and colour pattern data, a new species ofLysmatapossessing a long accessory branch from Pernambuco, northeastern Brazil. Our maximum-likelihood analysis recoveredLysmata elisasp. n. as a sister species toLysmata jundalini. Both species are closely related toLysmata holthuisiandL. intermedia. The four aforementioned species comprise theL. intermediaspecies complex. The new species may be morphologically distinguished from the other closely related species by different sets of characters, which include details of the dorsolateral antennular flagellum, armature of ischium of the second pair of pereiopods, intraorbital process shape and relative proportions of pereiopods. Our results reinforce the importance of refining biodiversity data through the application of integrative taxonomic approaches to expand the knowledge of local and global biodiversity. The biodiversity ofLysmatadeserves special attention, as they are intensively exploited in the aquarium trade.

Description of the complete larval development of Lysmata amboinensis (De Man) (Decapoda: Lysmatidae) reared under laboratory conditions.

Complete larval morphological descriptions are currently only known for three of the 48 species of genus Lysmata. The present study describes and illustrates the larval development of Lysmata amboinensis (De Man) reared under laboratory conditions. Lysmata amboinensis larval development is composed by a total of ten zoea and a decapodite stage. The first zoeal stage larvae presents sessile eyes, a carapace with a pterigostomial spine and anterio-ventral marginal denticles, a long, slender, and pointed rostrum, an antennal exopod terminally articled, a pleon with five somites, the fifth one bearing a pair of dorso-lateral spines on the posterior margin, and a triangular shaped telson with 7+7 posterior processes. The decapodite resembles a smaller adult and has extremely long antennas (more than twice the total length of the decapodite), the first two pair of pereiopods with chela, first four pairs of pereiopods with reduced and entire exopods, and fully developed pleopods. The morphological features of L. amboinensis are compared with those currently available for the larval stage of the genus Lysmata.

Why “swimming crabs” are able to swim – The importance of the axial skeleton: A comparison between the “swimming crab” Liocarcinus depurator and two other brachyuran crabs (Cancer pagurus, Carcinus maenas) using μCT and 3D-reconstruction

Most brachyuran crabs use their pereiopods as walking legs, but there are also a number of species, in which the last (5th) pair of pereiopods (P5) are specialized to permit a unique mode of swimming. One of these P5-swimming crabs is Liocarcinus depurator, commonly found on European shores. We present 3-dimensional μCT-based reconstructions of the axial skeletons and 5th pereiopods (P5), including the intrinsic and extrinsic musculature of the P5, of L. depurator and of two other non-swimming brachyuran crabs, Cancer pagurus and Carcinus maenas. In Liocarcinus, we also present a reconstruction of the 4th pereiopod (P4) together with its intrinsic musculature. We further use 3-dimensional prints of the reconstructed P5 coxa and basi-ischium of L. depurator as well as thoracal parts near the thoracal−coxal arthrodial cavity to build a model which can simulate the effects of muscular activity based on muscle insertions in our 3D reconstruction and under various simulated tensile vectors. This enables us to test muscular functions that had previously been speculated upon. Reconstructed morphological structures are compared to find differences that may explain why of the three species, only L. depurator is able to swim. Significant differences between Liocarcinus and the non-swimmers Cancer and Carcinus were found in the shape of the axial skeleton, external P5 morphology and the dimensions and origin sites of the extrinsic P5 musculature, but not in the intrinsic musculature of the P5. Inclination angle measurements of P1 thoracal−coxal articulation axes against P5 axes showed that in Cancer and Carcinus, angles in the longitudinal plane were smaller than in the lateral one, whereas in Liocarcinus, they were greater. Inclination angles in the longitudinal plane were also much greater in Liocarcinus than in Cancer and Carcinus. 3D print muscular activity simulation showed that muscles inserting at the basi-ischium, which are often referred to as “levator” or “depressor” muscles, may actually also function as promotors or remotors, depending on the tensile vector within which the muscle is acting.

Two new species of South American freshwater crayfish genus ParastacusHuxley, 1879 (Crustacea: Decapoda: Parastacidae).

Two new species of Parastacus Huxley, 1879 are described from material collected in the state of Rio Grande do Sul, southern Brazil: Parastacus fluviatilis sp. nov. from highland streams and Parastacus caeruleodactylus sp. nov. from wetlands. Parastacus fluviatilis sp. nov. is distinguished mainly by large chelipeds with dense setae cover on the cutting edge of fingers, telson subtriangular with two lateral blunt spines and strongly concave ventral surface of lateral process of thoracic sternites 6 and 7. Parastacus caeruleodactylus sp. nov. is distinguished mainly by blue cheliped fingers and a large gap between them, reduced abdomen, dorsal and ventral margins of dactylus, propodus and carpus of second pair of pereiopods with tufts of long setae and mid-dorsal carina of exopod of uropods unarmed. According to IUCN Red List criteria both species are considered endangered. Habitat characterization and a method for defining the shape of second abdominal pleura are also provided.

Abnormal reproductive morphology in two species of spiny lobster: Jasus edwardsii and Jasus paulensis

Jasus edwardsiiandJasus paulensisare two species of spiny lobster that are distributed across south-eastern Australia and isolated islands of the southern Indian Ocean, respectively. We present rare examples of abnormal reproductive morphology in both species. ForJasus edwardsii, this included a female lobster captured in South Australia, which, in addition to the normal pair of gonopores at the base of the third pair of pereiopods, also exhibited a second a pair of gonopores on the coxopodites of the fourth pair of pereiopods. In Tasmania, a male individual exhibited the specialized pincer on the right propopodite, normally only observed in females. The frequency of abnormal morphological reproductive characteristics appeared higher inJasus paulensis. This included 14 individuals that exhibited a range of additional and abnormal gonopore locations in both males and females. We discuss the findings in relation to rare cases of gynandromorphism in crustaceans.

A new deep-water species of Odontozona (Decapoda: Stenopodidea: Stenopodidae) from the East Pacific, and new record of O. foresti Hendrickx, 2002.

A new species of the stenopodid shrimp Odontozona is described from deep-water off the west coast of Mexico. It is distinguished from the three other species of the genus known in the area, from O. rubra Wicksten, 1982, and O. foresti Hendrickx, 2002, by the absence of a series of spines on the posterior half of the carapace, behind the post-cervical groove, and from O. spongicola (Alcock & Anderson, 1899) by the presence of spines on the ventral margin of somites 1-5 (smooth in O. spongicola) and by the much slender third pair of pereiopods in the new species. A new record is provided for O. foresti, and the first male specimen, the third specimen on record, is compared with the female holotype.

New retroplumid crabs (Crustacea, Brachyura, Retroplumidae Gill, 1894) from the Eocene of Huesca (Aragón, Spain).

Two new brachyurans assignable to the family Retroplumidae Gill, 1894, Serrablopluma diminuta n. gen., n. sp., and Gaudipluma bacamortensis n. gen., n. sp., from the Eocene of northern Spain (Huesca, Aragón), substantially enlarge our current knowledge of the morphological diversity of the family. The material, with well-preserved ventral surfaces, permits the erection of two new genera that can be referred to the family with confidence on the basis of the general carapace shape, narrow front, a reduced last pair of pereiopods and characteristic thoracic sternum (broad, trapezoidal sternites 3, 4, subrectangular sternites 5-7, sternite 8 conspicuously reduced and inclined). Serrablopluma diminuta n. gen., n. sp. co-occurs with two other retroplumids in the most diverse fossil assemblage of that family known to date.

A new species and new records of 'Oncinopus' (Crustacea: Brachyura: Inachidae) from Northern Australia

A new species of the Indo-west Pacific majoid spider crab genus Oncinopus is described from Darwin Harbour (Northern Territory), as well as the North West Shelf (Western Australia) and the Gulf of Carpentaria (Queensland). It can be distinguished from other species by differences in the morphology of the male first gonopod, rostral shape, the setation of the dactyl of the first pereiopod, and the length of the last two pairs of pereiopods. Oncinopus angustifrons Takeda and Miyake, 1969 is recorded from the North West Shelf, and is the first record of this species from Australia. Oncinopus aranea (De Haan, 1839) is recorded from northwestern Australia for the first time. Five species of Oncinopus are now recognised, with four of these now known from Australia. A key to distinguish them is provided.

Development of secondary sexual characters in juvenile males of Benthana cairensis (Crustacea, Oniscidea, Philosciidae)

Terrestrial isopods undergo direct development in which the animals molt to juvenile stages after the manca stages in which the sex cannot be recognized. The first three juvenile stages of Benthana cairensis are described with emphasis on the male secondary sexual characters. The ontogeny of the genital papilla, pleopods 1 and 2 and pereiopods were followed. At the Juvenile I stage, males are characterized by a slightly developed papilla, although dimorphism of the pleopod 1 exopod and pereiopods is still not evident at this stage. In Juvenile II individuals, the sub-apical protrusion of the pleopod 1 exopod begins to appear, and it is more evident in Juvenile III. The complete formation of this protrusion is only seen when males reach a cephalothorax width of approximately 1.0 mm; dimorphism of the setation of the four pairs of pereiopods begins later and is evident when males reach approximately 1.04 mm CW.

Feeding Behavior of the Horned Shrimp, Paracrangon echinata (Caridea: Crangonidae)

Abstract Stomach content analysis and behavioral observations reveal that the horned shrimp Paracrangon echinata is a lie-in-wait predator on smaller organisms, especially amphipods, polychaetes, and caridean shrimp. Prey is detected using the extremely thin third pair of pereiopods, captured with the subchelate first pereiopods, and ingested whole.

New early Jurassic decapod crustacean from Patagonia (Chubut province), Argentina

A well-preserved decapod specimen was found in early Toarcian deposits cropping out on the western slope of Meseta Catreleo, central Chubut province, Argentina. It is a nearly complete exoskeleton preserved in lateral view, slightly crushed, in fine-grained sandstones. The skeleton is mostly articulated, though some pieces are disarticulated or missing. Taphonomic features indicate a relatively rapid burial after death, with little or no transport. This specimen is here described as a new species of the genus Mecochirus Germar (Decapoda: Glypheoidea). Mecochirus robbianoi n. sp. is characterized by a very long, achelate, first pair of pereiopods with a narrow, long, straight dactylus, a thin carapace ornamented by low tubercules, with a slightly oblique cervical groove and a short acute rostrum. The family Mecochiridae arose in the Triassic, but the group diversified during the Early Jurassic. Mecochirus had a wide geographical distribution and is known for sure from Lower Jurassic to Upper Cretaceous deposits. The new record from Chubut is one of the oldest for the genus, the oldest for South America, and the first for Argentina, thus considerably extending the known distribution of the genus during the Early Jurassic.

Macrobrachium santanderensis, new species of freshwater prawn (Crustacea: Decapoda: Palaemonidae) from the northeastern Andes mountains of Colombia

There is only one species of freshwater prawn documented for the Catatumbo region, which is part of the northeastern Andes mountains of Colombia. Morphology comparison with other Colombian Macrobrachium species which inhabit the nearby Orinoco river basin such as M. brasiliense, M. cortezi, M. heterochirus, and M. reyesi, and the only species reported for the Catatumbo region (M. praecox) reveals distinct characters of a new freshwater prawn species. The differences between the new species described herein and the previously reported Macrobrachium species are in the ornamentation of the rostrum and the second pair of pereiopods, proportion of some segments of the second periopod, as well as size and number of eggs. The new freshwater prawn species (Macrobrachium santanderensis) is reported, described, and illustrated.

Description of the Male Reproductive System of the Hermit Crab Calcinus Tibicen (Decapoda: Anomura: Diogenidae)

We describe the male reproductive system of the intertidal hermit crab Calcinus tibicen, with emphasis on the sexual apparatus, spermatophore, and spermatozoa. The crabs were collected on the rocky shore of Praia Grande Beach, Ubatuba, southeastern Brazil. The morphological analysis, based on 30 specimens, was made with the use of a stereomicroscope, an optical microscope, and scanning and transmission electron microscopes. The male reproductive system is composed of a pair of juxtaposed testes, located dorsally in the pleon. From each testis emerges a vas deferens that links it to the exterior by the gonopores, located on the base of the fifth pair of pereiopods. The vas deferens has three macroscopically distinct regions that contain spermatophores in different stages of maturation. The spermatophore morphology is similar to that of other members of Paguroidea, having a distal, nearly spherical ampulla containing spermatozoa; an approximately cylindrical peduncle; and a proximal foot connecting the spermatophores. We describe, for the first time, the variability in the spermatophore morphology and size in the three regions of the vas deferens using the type species of the genus Calcinus. The spermatozoa have three main regions (the acrosomal vesicle, the nucleus, and the cytoplasm). The morphological similarity of the male reproductive system of C. tibicen with previously studied species of Diogenidae is an indicative of complex phylogenetic relationships among the members of the genus.

Métodos de extrusão manual e elétrica dos espermatóforos de reprodutores selvagens do camarão-rosa Farfantepenaeus paulensis (Decapoda: Penaeidae)

O presente estudo comparou os métodos manual e elétrico de extrusão do espermatóforo do camarão-rosa Farfantepenaeus paulensis com o objetivo de verificar se os métodos de extrusão exercem influência na quantidade de células espermáticas e na regeneração de novos espermatóforos. Os machos foram extrusados no início (dia zero) e no final do experimento (dia 43) para verificação da eficiência dos métodos no processo de regeneração. A extrusão manual foi realizada por meio de pressão na região do quinto par de pereiópodos e o método elétrico com uso de eletrodo para transmissão de impulso elétrico de 9 volts na mesma região. Os dois métodos foram considerados eficientes, não sendo encontradas diferenças significativas entre estes (P>0,05) para o número de células espermáticas. Entretanto, foi verificada, no final do experimento, a perda de peso corporal, peso de espermatóforo e menor índice espermatossomático (IES) (P<0,05) nos animais submetidos a extrusão do espermatóforo por estímulo elétrico. Os valores médios finais (±DP) do número de espermatozóides foram 1,46 (±0,84) e 3,25 milhões (±2,12) para os tratamentos com método elétrico e manual, respectivamente. Os resultados indicam que ambos os métodos podem ser utilizados para a coleta inicial de espermatóforos e testes de qualidade de espermatozóide. Entretanto, para a reutilização dos machos após a extrusão inicial do espermatóforo, o método manual é mais indicado pela manutenção do número de células espermáticas, peso do espermatóforo, peso corporal e índice espermatossomático após a regeneração.

An Ultrastructural Study of Tegumental Glands of the Fifth Pereiopods of Aegla Platensis (Anomura: Aeglidae)

Abstract Tegumental glands are a ubiquitous feature of the decapod cuticle. In the fifth pair of pereiopods (P5) of Aegla platensis Schmitt, 1942, these tegumental glands (PeTG's) are similar to those described in other decapod crustaceans. Type 1 PeTG's, with mucous and serous cells and type 2 PeTG's, with serous cells only are organized into proximal, medial and distal clusters along the appendage. Both types of PeTG's possess secretory cells arranged concentrically around a central duct. These secretory cells have well developed Rough endoplasmic reticulum (RER) and numerous Golgi Complexes, and possess electron-lucid and electron dense vesicles. The finely granular aspect of the electron-lucid vesicles suggest they contain a mucous-like substance, while electron-dense vesicles probably contain a substance of a proteinaceous nature. Despite various hypotheses, there are few indications that these substances act as cleaning agents. However, the cytoplasm of the secretory cells appear to be composed of c...

Partial Protandric Hermaphroditism in the Burrowing Crayfish Virilastacus Rucapihuelensis Rudolph and Crandall, 2005 (Decapoda, Parastacidae)

Rudolph and Crandall (2005) found a high percentage (81.3%) of intersex specimens with supernumerary gonopores in the Virilastacus rucapihuelensis type series. To determine the sexual system of this species, the sexual characters of 734 specimens collected from 5 populations of V. rucapihuelensis were examined. Six sexual forms were initially identified, on the basis of the presence or absence of gonopores in the coxae of the third and fifth pair of pereiopods. Subsequently, anatomical and histological analysis of gonads, gonoducts and androgenic gland, made it possible to distinguish three basic sexual types: male, female and intersex specimens; the latter comprise a male phase and two forms in female phase, which would originate from male phase intersexes. Ovigerous females and secondary sexual characters associated with eggs incubation were identified in adult females and in the intersexes in female phase. Evidence gathered suggests that V. rucapihuelensis is a partial protandric hermaphrodite species, with primary males and females. The possible neurohormonal mechanisms responsible for this type of sexual system are discussed, as are the external factors that could have a modifying effect on them.

Diferenciación sexual en la langosta de agua dulce Cherax quadricarinatus (Decapoda: Parastacidae)

Determinamos el momento del desarrollo postembrionario en que se produce la diferenciación sexual primaria en la langosta Cherax quadricarinatus. Esta es evidenciada por la presencia de las gónadas y sus respectivos conductos. También determinamos la diferenciación sexual definida por la aparición de los caracteres sexuales secundarios. Se observaron 797 machos, 506 hembras y 456 individuos intersexos de 0.02 a 89.96 g (de criadero y laboratorio). Disecamos una submuestra de 106 machos, 69 hembras y 59 individuos intersexos para la caracterización macroscópica de la estructura gonadal. La diferenciación de los gonoporos se inicia aproximadamente a los 0.10 g, en sincronía con la diferenciación del sistema reproductor en machos, hembras e intersexos. La adquisición de la forma definitiva de ovario, oviducto, testículo y vaso deferente son posteriores. El appendix masculina inicia su diferenciación a los 0.12-0.2 g y adquiere los rasgos característicos del appendix de los adultos a partir de 1-2 g. La diferenciación de la mancha roja (red patch) ocurre a partir de los 2,3 g.

A new pinnotherid crab (Decapoda: Brachyura: Pinnotheridae) from the Miocene Niijukutoge Formation, northeast Japan

A new fossil pinnotherid crab, Globihexapus kosekii sp. nov. is described from the early to middle Miocene Niijukutoge Formation in Shichikashuku-machi, Miyagi Prefecture, northeast Japan. Based on the presence of five pairs of pereiopods as revealed in an examination of the present material and reexamination of the types of Globihexapus Schweitzer and Feldmann, 2001, this genus is transferred from the family Hexapodidae Miers, 1886 to the subfamily Asthenognathinae Stimpson, 1858 of the family Pinnotheridae de Haan, 1833.

Mating Without Anterior Pleopods in a Simultaneous hermaphroditic shrimp, Lysmata Wurdemanni (Decapoda, Caridea)

The effects of copulatory rami removal of male-role shrimp (male-phase (MP) or euhermaphrodi te-phase (EP)) on mating behavior of a simultaneous hermaphroditic shrimp, Lysmata wurdemanni, were investigated in the laboratory. There was no difference in general mating behavior between male-role shrimp with or without ablation of copulatory pleopods. However, ablation highly significantly (P < 0.001) affected copulation frequency. The influence was also sex dependent (P < 0.001). In general, copulation frequency in ablated EP shrimp was significantly higher (P < 0.05) than in ablated MP of the same treatment. Ablation of either pleopod 1 or pleopod 2 in MP shrimp did not affect mating behavior or spermatophore transfer. The success of spermatophore transfer was negatively correlated with the mean copulation frequency (R = ?0.9707, P < 0.001). Normally, spermatophores were deposited on the base of the last two pairs of pereiopods. Ablation of the pleopods may lead to failure of emission or improper deposition of a spermatophore. Some new mating behaviors are described and a possible mating mechanism for the shrimp is proposed.