Male Pleopod Research Articles

Revision of the genus Porcellionides Miers, 1877 (Isopoda: Porcellionidae) in the Ibero-Balearic region

Until now, the genus Porcelliniodes Miers, 1877 is represented in the Ibero-Balearic region by seven species. The study of 721 specimens from Portugal and Spain has led to the identification of 11 species, including poorly known species, and the description of a new species, Porcellionides ibericus sp. nov. This new species is characterized by the absence of transverse ridges on the pereonites, medium-sized lateral lobes on the cephalon, the pleon slightly retracted in relation to the pereon, pereopods without sexual differentiation, and a truncated posterior inner tip in the male pleopod I. We consider P. glaber (Koch, 1856), P. hispanus (Vandel, 1953), P. lucasioides (Vandel, 1953), P. lusitanus (Vandel, 1946), and P. molleri (Verhoeff, 1901) as valid species, while P. buddelundi (Verhoeff, 1901) and P. rufocinctus (Dollfus, 1892) are considered species inquirendae. Five species are recorded for the first time in some Portuguese districts and seven in some Spanish provinces.

A new species of Janiralata Menzies, 1951 (Isopoda: Asellota, Janiridae) from Korea

A new isopod species, Janiralata kwangsooi sp. nov., from Dokdo Island located in the East Sea off the Korean Peninsula is described here. This species is distinguished from its congeners by the number of antennular articles, setation of mouthparts and pereopods, length and width ratio of appendages, and shape of male pleopods I and II. To aid species identification, a taxonomic key to species of Janiralata Menzies, 1951 in the Japanese and Korean waters is provided. A partial sequence of mitochondrial cytochrome-c-oxidase (COI) of this new species is also provided for DNA barcoding and compared with those of congeners publicly available in GenBank.

Trans-Japan Sea land-bridge disjunction: A case of vicariance in the subterranean genus Nipponasellus (Crustacea, Isopoda, Asellidae) in a large-scale biogeographical context.

This study examines nineteen phreatobiological hand pump samples collected in 20092010 in three separate areas of salmon river basins in the southern part of Primorye, in the Far East of Russia. For the first time, faunal groundwater patterns were assessed for the rivers of Eastern Manchuria, the Ussury River Basin and the rivers of the south-western slope of Sikhote Alin. A total of 164 species (including 32 stygobionts) belonging to the phyla Annelida, Mollusca and Arthropoda are first records of groundwater animals, and two of the stygobionts are described below as new species for Science. Nipponasellus sudzukhensis spec. nov. and N. matsumotoi spec. nov. are described and illustrated, and their taxonomic affinities with congeners are discussed. The morphology of male pleopod 2 of the genus Nipponasellus is re-examined using scanning electron microscopy (SEM), which revealed fine details of the pleopodal structures. The two new continental species of Nipponasellus were characterised by a distinct cannula completely immersed in ctenoid cuticular scales and the absence of a labial spur. Informal macrogroups were proposed based on the structure of the appendix masculina and an analysis of family distribution. The results of cladistic analyses revealed relationships between the proposed groups, but phylogenetic relationships within the Caecidotea-Proasellus group remain challenging. Common diagnostic characters of Nipponasellus showed that the group occupies an independent position close to the Caecidotea-Proasellus group rather than the Asellus-pattern sensu Magniez. Revised diagnosis for the genus Nipponasellus is given, including the two new species and the five previously described ones. The species diversity of East Asian stygobiotic asellid isopods is briefly reviewed to infer a biogeographic distribution pattern that emphasises the strict endemicity of members of the genus Nipponasellus. The intracontinental separation between continental Far East Asia and the Japanese archipelago highlights the biogeographic importance of the land-bridge in the Oligocene and raises questions about hypotheses explaining the (disjunct) distribution in East Asia, together with the circumstances preceding an ancient colonisation of the region.

A new species of Janiralata Menzies, 1951 (Isopoda: Janiridae) from Japanese bathyal waters, with a review of the associations with invertebrates among the species of Janiralata

Abstract Isopods of the genus Janiralata Menzies, 1951 (Asellota: Janiridae) are known from shallow and deep waters of the Northern Hemisphere. Most species are free-living, but some are symbiotic on the surface of other benthic invertebrates. We obtained from three beam- and four otter-trawl hauls 18 Janiralata asellote specimens from the bathyal zone off the Pacific coasts of Tohoku, northeastern Japan. Partial nucleotide sequences of the mitochondrial cytochrome c oxidase subunit I (COI) gene (505 bp) were determined for 16 of the 18 collected specimens. Non-significant genetic differences (< 0.8%) indicated that the individuals were conspecifics. Morphological analysis indicated that all the specimens belonged to a single species, Janiralata planasp. nov. based on the unique morphology of the anterolateral and distolateral projections on the head and pleotelson, surface and lateral margins of the body, antennula article 1, and of the male pleopod 1. Six of the 18 collected specimens were found attached to the surface of an unidentified sea anemone (Hormathiidae), ten to the solasterid starfish Crossaster borealis Fisher, 1906 and two were obtained from the bottom sediment. Three COI haplotypes of the new species were shared by individuals from two neighboring sites, which suggests that genetic isolation occurs on a relatively narrow horizontal scale, although the bathymetric distribution range was rather wide. We describe a case study of the geographic and bathymetric distributions of an asellote species with low dispersal ability and its genetically differentiated populations. Such approach could help elucidate the diversity and distribution of deep-sea organisms and their diversification processes.

A new species of Metaprosekia Leistikow, 2000 (Oniscidea, Philosciidae) from caves of the State of Mato Grosso, Brazil

ABSTRACT The present work aims to describe a new species of Metaprosekia from siliciclastic caves from Caverna Nova and Caverna Ponte de Pedra, Utiariti Formation, Municipality of Diamantino, State of Mato Grosso. Metaprosekia utiariti n. sp. easily differs from the congeneric species in the shape of male pleopods 1 and 2. Moreover, a map illustrating the lithology and hydrographic characteristics where the specimens were collected and conservation remarks are given. http://www.zoobank.org/urn:lsid:zoobank.org:pub:F0B93B6A-0FBF-4B66-B6F0-3E5B67DD9C53.

Description of two new janirid isopods (Isopoda, Asellota, Janiridae) from Korean waters.

Two janirid isopods, Caecijaera ciliata sp. nov. and Janiralata truncata sp. nov., are reported from Korean waters in this study. Caecijaera ciliata sp. nov. differs from its congeners by the following features: pereonites 47 with large simple setae on the midline of the posterior tergite margins; the pleotelson is angled proximolaterally; the antennula is six-articled; the basis of pereopod is serrated superiorly; and the appendix masculina is not coiled. Janiralata truncata sp. nov. can be distinguished from its related species by the following characteristics: the lateral margin of the cephalothorax has an acute projection anterolaterally; all coxal plates of the pereonites are visible dorsally; male pleopod has a pair of small rounded projections distally near the fusion line of the two first pleopods; the exopod of pleopod has two plumose setae on the distomedial margin.

Phylogeographic analysis of Ligidium japonicum (Isopoda: Ligiidae) and its allied species reveals high biodiversity and genetic differentiation in the Kanto region, Japan

AbstractResearch of the diversity and evolutionary history of Japanese soil invertebrates is scarce. Molecular data analysis can help to elucidate species classifications and evolutionary processes. We analyzed the mitochondrial cytochrome oxidase subunit I (COI) and nuclear 28S rDNA genes and the morphology of the male pleopod 2 endopod of Ligidium japonicum and its allied species from 67 sites in Hokkaido, Honshu and Shikoku, where only L. japonicum is thought to occur. We found males of the L. japonicum complex with a pleopod 2 endopod morphology matching that of the L. japonicum syntype specimens, except for the number of denticles at the inner margin. There were also more than five species that differed morphologically from the L. japonicum complex, and most of these species had allopatric distributions despite the absence of obvious barriers. A time‐calibrated molecular phylogeny implied that the L. japonicum complex of the Kanto region first differentiated allopatrically in the mountains; this was followed by independent dispersal of three lineages to the Kanto Plain and Boso Peninsula, where secondary contact occurred. Two of the three sympatrically distributed L. japonicum complex lineages had a significant difference in the number of denticles at the inner margin of male pleopod 2 endopods. This variation implies the presence of cryptic species within the L. japonicum complex.

Two axiidean ghost shrimps (Crustacea: Decapoda) from India, Guyanacaris keralam sp. nov. (Axiidae) and Paragourretia galathea (K. Sakai, 2017) (Ctenochelidae).

Ghost shrimps collected from the Indian Exclusive Economic Zone by the Fishery Oceanographic Research Vessel Sagar Sampada during two cruises in the eastern (105 metres depth) and southeastern Arabian Sea (101 and 326 metres depth) were studied. One male, identified as Guyanacaris keralam sp. nov. of the Axiidae, differs from its congeners in the unique armature of the rostrum, gastric region of carapace, pleonal pleural margins, dorsal margins of cheliped fingers, ventral margin of second pereopod merus, and lateral margins of telson; the presence of corneous spines on the propodi and dactyli of third and fourth pereopods, and the relative sizes of the ocular peduncles, antennular peduncle, scaphocerite and cheliped fingers. Guyanacaris K. Sakai, 2011 is re-diagnosed based on the presence of short supraocular spine and post-cervical carina on carapace, dentate margins of first two pleonal pleura, third to fifth pleura with angular to straight posterior margins, antennal scaphocerite with mesial spine at base, and presence of male first pleopod 1. Bruceaxius thailandensis K. Sakai, 2015 is tentatively retained in Bruceaxius K. Sakai, 2011, owing to absence of mesial spine at the base of scaphocerite, tuberculate upper margins of carpus, propodus and dactylus of major cheliped, and tri-segmented appendix masculina on male second pleopod. In addition, two males, diagnosed herein as Paragourretia galathea (K. Sakai, 2017) of the Ctenochelidae, differ from the holotype female only in the relative length of the terminal antennular article and the presence of a distomedian spinule on the telson, of all the features.

A new species of Spelunconiscus (Isopoda: Oniscidea: Styloniscidae) for Brazilian caves: new record for the type species and an emended diagnosis for the genus

Spelunconiscus Campos-Filho, Araujo and Taiti, 2014 is a monotypic genus of the family Styloniscidae represented by a troglobitic species, Spelunconiscus castroi Campos-Filho, Araujo and Taiti, 2014, from the cave MOC-32, in the state of Minas Gerais, southeastern Brazil. New representatives of this family were found in three additional caves, which revealed a new species, Spelunconiscus septemlacuum sp. nov., from Taboa and Tatuzinhos caves and a new occurrence for the type-species in Retiro cave. The original diagnosis of Spelunconiscus is emended due to the discovery of a spur-like structure in the male pereopod VII ischium, as well as some supplementary traits that have not been previously considered. Spelunconiscus septemlacuum sp. nov. differs from S. castroi in the number of articles of the antennal flagellum, in the proportion between this flagellum and 5th article of peduncle of antenna, in the size of maxilliped endite, in the morphology of male pleopod II and in body size. A discussion is provided for both taxonomic and ecological concerns.

Agnara cavernicola, the second troglophilic terrestrial isopod species (Isopoda: Oniscidea) from Iran

ABSTRACT The first cave-dwelling terrestrial isopod species of the genus Agnara Budde-Lund, 1908 is described from Zarneh Cave, western Iran. Agnara cavernicola Bakhshi and Kashani, sp. nov. is characterised by a reduced number of ommatidia and body pigments. Moreover, it differs from the congeneric species by the shape of male pleopod exopodites I and male pereopods VII. http://urn:lsid:zoobank.org:pub:B0DDD1CE-B6B6-44A9-A8AC-E2AF3F0EBE54

Three new species of Androdeloscia Leistikow, 1999 (Oniscidea: Philosciidae) from the Brazilian Amazonia.

Three new species of Androdeloscia Leistikow, 1999 from the Brazilian Amazonian rainforest are described. Androdeloscia bicornuata sp. nov., A. paraleilae sp. nov., and A. micropunctata sp. nov. were distinguished from the 26 other species of the genus mainly based on the shape of male pleopod I endopod. Androdeloscia bicornuata sp. nov. differs from all the species in the genus by the complex morphology of the distal portion of the male pleopod I endopod bearing hyaline lamella and two horn-like tips. Androdeloscia paraleilae sp. nov. is characterized by the male pleopod I endopod with simple distal portion, without hyaline lamella, and apex represented by a curved tip and inner margin serrate proximally; and by the concavity on the lateral margin of the first maxilla (except for the A. leilae that is related to other listed characteristics). Androdeloscia micropunctata sp. nov. differs from the remaining species of the genus by the male pleopod I endopod with simple distal portion, without hyaline lamella, and apex truncate bearing a small acute tip in the outer corner; and 5+5 teeth on the first maxilla. Some characters related to the genus are later discussed.

Three new microcerberids (Isopoda: Microcerberidae) from subterranean freshwater habitats in Texas, USA

ABSTRACT The stygobiontic genus Texicerberus gen. nov. and the three species T. amistad sp. nov., T. schotteae sp. nov., and T. castilloi sp. nov. are described from freshwater aquifer or hyporheic sites across central and western Texas, USA. The status of the new genus and species is based on morphological characters that distinguish them from all other described Microcerberidae from both marine and freshwater environments. Cephalon without rostral projection, coxae II–IV rounded, medial margin of antenna article 3 angulate but not produced as spine, male pleopod II endopod uniramous, and male pleopod IV biramous are among the characters that distinguish Texicerberus gen. nov. from other genera in the family. Collected from deep karst aquifer wells, karst springs, and the hyporheic zone along the Rio Grande (Rio Bravo del Norte), these three new species represent the first documented occurrences of Microcerberidae in Texas and substantially increase the described diversity in the family in North America and from freshwater environments globally. Additional sampling, especially in the hyporheic zone, is expected to reveal additional diversity in Texas. Future collection and analysis of molecular data will be required to understand the evolutionary relationships among these and other species.

Three new species of Heteromysis (Crustacea: Mysida) from coral reef aquaria in Florida and Central Europe.

Three new species of the genus Heteromysis S.I. Smith, 1873 (tribus Heteromysini), are described from a rich stock of mysids obtained on request from the international community of professional aquarium keepers. The 18S rDNA and COI sequences of the three species were distinct from each other and also from other sequences published in DNA databases. Heteromysis (Olivemysis) schoenbrunnensis sp. nov. is morphologically characterized within the subgenus Olivemysis based on the structure of the first and second antennae, male pleopods, uropods, and telson. Heteromysis (Heteromysis) gulfarii sp. nov. is outstanding within the subgenus Heteromysis by sexually dimorphic modified setae on the antennular trunk. These setae are non-dimorphic in the very similar Heteromysis (Heteromysis) korntalensis sp. nov. Both species H. gulfarii and to a lesser degree also H. korntalensis show modified eyes, subquadrate in dorsal view, eyestalks anteriorly tapering in lateral view; small, well-developed cornea implanted laterally on modified eyestalk. Apart from eye structure H. gulfarii and H. korntalensis clearly fall morphologically within the nominotypical subgenus Heteromysis.

Four new species of Heteromysis (Crustacea: Mysida) from public aquaria in Hawaii, Florida, and Western to Central Europe

Four new species of the subgenus Heteromysis (Olivemysis) were detected in material from (sub)-tropical aquaria in six public aquarium institutions around the globe. Modifications of pleopods by spines represent the strongest structural complex used for differentiation within this subgenus: male pleopods 1–4 modified in H. smithsoniana sp. nov., male pleopods 2–4 plus female pleopod 2 in H. hornimani sp. nov. and H. waikikensis sp. nov. Additional important diagnostic characters are provided by the antennulae, uropods, and telson. The male of H. sixi sp. nov. represents a very rare case within the genus Heteromysis by having only pleopod 2 modified by flagellate spines. The definition of the subgenus Olivemysis is modified in order to include H. sixi sp. nov. A summary of pleopod modifications in the genus Heteromysis and a key to the species of the subgenus Olivemysis are given. The here described new taxa more than double the number of Heteromysis species known from aquaria yet unknown in nature from three to seven.

The First Insight into the Patterns of Size and Shape Variation of a Microcerberid Isopod

Cryptic species are a biological phenomenon only recently recognized due to progress in molecular studies. They pose a significant challenge to conventional taxonomic work since these species manifest low morphological differences, but considerable genetic disparity. New taxonomic methods are in development but have yet to be tested for many animal groups. Isopods belonging to the suborder Microcerberidea are one such group. The Asian microcerberid isopod, Coxicerberus fukudai (Ito, 1974), is a major component of marine interstitial fauna with suspected cryptic species inhabiting Japan and Korea. We chose six Korean populations with high molecular interpopulations divergence and applied 2D landmark-based geometric morphometrics to cephalic sensilla, pleonal points, and male pleopod II. This quantitative approach allowed us to study interpopulation size and shape variations, morphospace structure, and whether the morphological pattern mirrored the genetic species. We determined that a high degree of interpopulation size variation significantly influences shape changes. Once we removed the allometric effect, the size-corrected male pleopod II shape variations yielded a new species, C. jangsaensis sp. nov. At the same time, we were able to resolve the C. fukadai species complex.

Caridina sinanensis, a new species of stygobiotic atyid shrimp (Decapoda, Caridea, Atyidae) from a karst cave in the Guizhou Province, southwestern China.

From a biodiversity survey of a subterranean habitat near Sinan County, Guizhou Province, southwestern China, a new atyid shrimp of the genus Caridina H. Milne Edwards, 1837, C. sinanensissp. nov. was discovered. The new species can be separated from other congeners based on a combination of characters including depigmentation in body and reduction of eyes, small pigment spot at the centre of the cornea, the shape of rostrum and the endopod of the 1st male pleopod, and the relatively longer appendix interna on the appendix masculina of the 2nd pleopod. Mitochondrial COI and 16S rRNA gene sequences also support the establishment of the new species. Information on the habitat, and the levels of threat are discussed to guide the conservation of C. sinanensissp. nov.

Genetic diversity, phylogenetic position and morphometric analysis of Astacus colchicus (Decapoda, Astacidae): a new insight into Eastern European crayfish fauna.

The phylogeny of European crayfish fauna, especially with respect to Eastern European species, is still far from being completely resolved. To fill this gap, we analyzed most of the European crayfish species focusing on the phylogenetic position of the endemic crayfish Astacus colchicus, inhabiting Georgia. Three mitochondrial and one nuclear marker were used to study evolutionary relationships among European crayfish species, resulting in the unique phylogenetic position of A. colchicus indicating independent species status to A. astacus. Phylogenetic analyses revealed a deep molecular divergence of A. colchicus in comparison to A. astacus (6.5-10.9% in mtDNA and 1.1% in nDNA) as well as to Pontastacus leptodactylus and P. pachypus (5.5-10.0% in mtDNA and 1.4-2.4% in nDNA). Absent ventral process on second male pleopod and abdominal somites II and III with pleura rounded lacking prominent spines clearly indicate taxonomic assignment to the genus Astacus; however, the species is distributed almost in the middle of Ponto-Caspian area typical by occurrence of the genus Pontastacus. Several morphological indices linked to head length, carapace, and total body length and width were found to demonstrate apparent differences between A. colchicus and A. astacus. Although this study provides a novel insight into European crayfish phylogeography, we also point out the gaps in comprehensive study of the P. leptodactylus species complex, which could reveal details about the potential species status of particular species and subspecies within this genus.

A new species of Bragasellus (Isopoda, Asellidae) from NW Spain, with a key to the known species of the genus.

During a survey on the benthic invertebrates of the upper reaches of river Eo (Galicia, NW Spain), a dense population of epigean asellid isopods were detected in the source of the river. After examination, these specimens resulted to belong to a new species of the genus Bragasellus Henry Magniez, 1968. The new species comes to fill a geographical gap between the two alleged ancestral areas of the genus and is characterized by its appendix masculina (male pleopod II endopod), which bears a short but distinct cylindrical cannula and lacks basal process. Other characteristic traits are uniform black pigmentation in live specimens, pereopod I dactylus shorter than the palm of the propodus, smooth (instead of plumose) texture of the marginal setae on male pleopod I exopod, and pleopod III exopod with a straight internal side. In this job, description of the new taxon is provided, as well as a key to all the known species belonging to the genus.

A new species in the subgenus <i>Javanisomysis</i> in the genus <i>Anisomysis</i> (Crustacea: Mysida: Mysidae) for specimens collected from Lombok Island, Indonesia

Mysid specimens collected at Lombok Island, Indonesia were examined and assessed taxonomically. These specimens share morphological characteristics with species of the subgenus Javanisomysis (genus Anisomysis). They are separable from the other four known species of the subgenus by the structure of the fourth male pleopod, and the condition and pattern of sub-segmentation in the third to eighth thoracopodal carpopropodi of both sexes. The male pleopod is long and reaches the posterior end of the sixth abdominal somite, excluding the apical barbed setae, and the first segment of the pleopod is broader in the proximal one-fourth to one-third. The third to eighth thoracopodal carpopropodi are divided distally into two segments. The population from Lombok Island thus is considered an undescribed species of the subgenus. On the basis of characteristics of the fourth male pleopod, a key to species of the subgenus is provided.

Distribution, identification and range expansion of the common Asellidae in Northern Europe, featuring the first record of Proasellus meridianus in the Nordic countries

Two out of the three common Asellidae species in Northern Europe are increasing their ranges, aided by humanactivities. Here we report the discovery of Proasellus coxalis (Dollfuss 1892) in new areas in Norway and thediscovery of Proasellus meridianus (Racovitza 1919) for the first time in the Nordic countries, verified withDNA barcoding. A new, detailed photo-identification guide to Asellus aquaticus Linnaeus 1758, P. coxalis andP. meridianus is presented. In addition to head pattern, attention is drawn to the female pleopods as an easy way to differentiate between the two genera. Then detailed examination of male pleopods 1 and 2 can differentiate between P. coxalis and P. meridianus. The origins, competitive relationships and potential dispersal mechanisms of the two introduced species and the native A. aquaticus are explored. By examining the shipping activity at the small, freshwater port where P. meridianus was found, we highlight the great connectivity between many European brackish and freshwater ports and possible pathways for species transfer. The risk of trans-oceanic freshwater to freshwater (not just brackish and saltwater) species transfer through ballast water needs to be better communicated. Proasellus coxalis may have been introduced to the river system of Lake Stokkalandsvatnet together with fish transported in microaquaria used as live bait for fishing.