The setae of Eurydice pulchra (Crustacea: Isopoda)

The setal armature of Eurydice pulchra Leach is described using an ordinary optical microscope. On the basis of size, setae are divided into macrotrichs and microtrichs. Macrotrichs are further classified according to structural similarities into four groups. Only two types of microtrichs have been recognized. The distribution of the different setae on both adults and juveniles is described and where possible an attempt is made to relate morphology and distribution to function.  

Summary:

The setal armature of E. pulchra has been divided into macrotrichs, varying in length from 0·025 to 0·4 mm, and microtrichs varying in length from 2 to 10 μm. The macrotrichs have been classified into groups based on structural similarities and 17 distinct types have been recognized. Each differ in length, degree of chitinization and modification of the shaft wall. The distribution of the macrotrichs has been described and particular types have been shown to occur in distinct positions on the body. Many of the macrotrichs are peculiar to one position on the body.
Two types of microtrichs have been described, a single type approximately 10 μm in length and a smaller type 2 μm in length. The latter occurs in short crescentic rows principally on the pleopods and oostegites. All setal types occurring in the adult have been shown to be present in the newly emerged juvenile although the number developed is very much less. Similar setal types are present in males and females. An attempt has been made to relate the morphology and distribution of both macrotrichs and microtrichs to possible functions.     

Gut repletion during diel vertical migration in the benthopelagic crustacean Eurydice truncata Norman, 1868 (Isopoda, Cirolanidae)

The sand-burrowing isopod Eurydice truncata migrates from thebenthos up to the neuston layer during the night. The gut contentsof vertical migrant animals sampled in nocturnal neuston haulsoff the Mediterranean coast of France were examined. The haulswere performed, on the one hand, from dusk to dawn, at a singlestation on the shelf and another on the slope, and, on the otherhand, in the middle of the night, at various stations from theinner shelf to the slope. In shelf waters, the percentage rateof filled guts increased quickly after dusk and had reachedalmost 100% after 3 h of darkness. Isopods feed on living neustonicanimals, preferably immobilized or passive living matter suchas insects trapped at the surface or fish spawn. During thenight, the gut contents gradually became more compact, and theremains of prey became less identifiable. The dry weight ofthe compacted gut contents of a single adult averages 0.50 mg,including 0.26 mg of organic carbon. At dawn, the downward migrationleads to this neustonic matter being vertically transferredfrom thesurface layer to within the sediment. A decrease inthe animal's level of gut fullness occurs from inshore to offshorewaters; this decrease in the feeding activity might generatea high rate of mortality in animals advected to slope water. Rsum. L'isopode fouisseur Eurydice truncata migre du benthosjusqu'en surface durant la nuit Les contenus stomacaux d'animauxprlevs dans le plancton de surface durant lanuit ont t examines.Les pches taient effectues du crepuscule l'aube, dans unemme station du plateau et de la pente continentale, en milieude nuit dans les diverses stations d'une radiale littoral-pentecontinentale. Sur le plateau, le taux d'estomac contenant dela nourriture augmente trs rapidement aprs le crepuscule,atteignant prs de 100% aprs trois heures d'obscurit. LesIsopodes se nourissent au dpens des animaux present dans l'hyponeustonet prefrentiellement sur la matire vivante immobilis ou passivecomme les insectes pigs en surface et les oeufs de poisson.Les contenus stomacaux, lches en debut de nuit, deviennentpar la suite de plus en plus compacts, les debris de proiesdevenant indistincts. Chezl'adulte le poids sec d'un contenustromacal en tat compact s'lve en fin de nuit a 0,50 mg,le carbone organique reprsentant 0,26 mg. A l'aube, la migrationdescendante conduit a un transfert de cette quantit de matireneustonique de la surface jusqu' l'intrieur du sediment. Letransfert pourrait atteindre en certaines zones, lorsque lespopulations de l'Isopode sont denses, plusieurs centaines dekg par km². Une diminution du taux de repletion stomacal estobservsupede la zone interne du plateau a la pente continentale;cette dcroissance de l'activit trophiqueest susceptible d'engendrerun taux de mortalit lev chez les animaux dplaces par lescourants superficiels de la zone neritique vers la zone bathyale.     

First report on Mermithidae (Mermithida) infection in Ligidium sp. (Isopoda,Ligiidae)

Specimens of Ligidium sp. (Crustacea, Isopoda, Oniscidea) collected from Kanagawa Prefecture in Japan were found to be infected with parasitic nematodes. We have obtained two Mermithidae (Nematoda) by dissecting the fresh specimen and from the dead specimen of Ligidium, which marks the second known discovery of a mermithid infection in the order Isopoda. Herein, a report on the nuclear 28S rDNA and 18S rDNA sequence of the isolated Mermithidae nematodes and on the morphology of the juveniles is provided.     

The incidence of Livoneca sp. (Isopoda) on Helotes sexlineatus (Pisces) in Kuwait waters

Infestations of Livoneca sp. occur on the striped therapon, Helotes sexlineatus, in Kuwait waters. Infestation rate decreases as depth increases, and some infested fish were found in all samples examined; the occurrence of infested fish could not be used as a biological tag. One year and four year old fish were uninfested. Two and three year old fish showed different infestation rates (4.1% and 0.9 % respectively). No striped therapon carried more than one parasite.     

Thaumamermis cosgrovei n. gen., n. sp. (Mermithidae: Nematoda) parasitizing terrestrial isopods (Isopoda: Oniscoidea)

Summary A new mermithid nematode, Thaumamermis cosgrovei n. gen., n. sp. (Mermithidae: Nematoda) was found parasitizing two terrestrial isopods (Isopoda: Oniscoidea) in California. The hosts, Armadillidium vulgare (Latr.) (a pillbug) and Porcellio scaber (Latr.) (a sowbug) represent the first cases of isopods attacked by mermithid nematodes. The genus Thaumamermis can be distinguished from all previously described mermithids by the extremely dimorphic spicules, one being short and broad and the other long and filiform. It has been discovered that the nematodes are infected with an iridiovirus which commonly destroys the isopod hosts. ac]19800917     

Coulmannia rossensis sp. n. (Isopoda, Asellota, Paramunnidae) from the Ross Sea, Southern Ocean

A new species of Coulmannia, Coulmannia rossensis, is described from the Ross Sea, Antarctica. It is most similar to Coulmannia ramosae Castelló, 2004, but can easily be distinguished from this species bythe males yielding a pair of granulate humps on the dorsum of the pereonites 1-6 and a single granulate hump on the pereonite 7 and the free pleonite. Coulmannia rossensissp. n. is sexually dimorphic. The dorsal sculpture of the female bodies yield a single granulate hump on all the pereonites and free pleonite. The species of the genus Coulmannia are restricted to the Southern Ocean, and Coulmannia rossensissp. n. is the fourth species included in it.     

Antarcturus bovinus n. sp., a new Weddell-Sea Isopod of the family arcturidae (Isopoda: Valvifera)

Summary Antarcturus bovinus n. sp. (Isopoda, Valvifera) is described from the Antarctic Peninsula and the western and southern Weddell-Sea. This species can easily be recognized by the absence of large spines, the spine armature of the dorsal surface characteristic of other species is lacking. Only A. antarcticus Bouvier, 1910, A. coppingeri Miers, 1881, A. granulosus Nordenstam, 1933 and A. lillei Tattersall, 1921 are similar, but A. bovinus n. sp. can be discerned from these by the presence of blunt supraocular spines.Abbreviations used in text and figures A 1,2 antenna 1,2 - Hy hypopharynx - Md mandible - Md left mandible - Mx 1,2 maxilla 1,2 - Mxp maxilliped - P 1-7 pereopods 1-7 - Plp 1-5 pleopods 1-5 - rMd right mandible - Urp uropod     

Note on the Arcturidae from the Weddetl Sea and description of Antarcturus hempeli sp.n. (Crustacea, Isopoda, Valvifera)

New localities of several arcturids are reported from the Atlantic sector of the Antarctic Ocean. Antarcturus hempeli sp.n. is described and drawings from type material of the following species are presented: Antarcturus furcatus (Studer, 1882), A. polaris (Hodgson, 1902), A. glacialis (Beddard, 1886). A granulosus Nordenstam, 1933, A. antarcticus Bouvier, 1910, A. lillei Tattersall, 1920, A. coppingeri (Miers, 1881), A. hodgsoni Richardson, 1913. Of the 37 species known from the studied area only 6 occur in the high Antarctic Weddell Sea. It is suspected that the semi-sessile way of life yielded the evolution of many local species and races.     

Description of the terrestrial isopod mirtana costaricensis gen. et sp. n. from central America (Crustacea: Isopoda: Oniscidea)

An examination of isopod material deposited in the Museum of the University of Costa Rica, San Pedro, revealed a new genus and species of terrestrial isopods, Mirtana costaricensis gen. et sp. n. which is distinguished by its three‐articulate antennal flagellum, incurved coxal plates and prominent neopleurae, while noduli laterales and respiratory areas on any pleopod are apparently lacking. Despite this unique combination of characters, a closer relationship to the widely distributed neotropical genus Ischioscia Verhoeff, 1928 can be postulated because of similar structure of male pereopods 1 to 2 and pleopod 1 endopodite.     

Thermosphaeroma subequalum,n. gen., n. sp. (crustacea: Isopoda) from Big Bend National Park,Texas

A new species of the Sphaeromatidae (Thermosphaeroma subequalum) is described from thermal waters (32° –35dgC) in Big Bend National Park, Brewster Co., Texas. A new genus, Thermosphaeroma, is proposed to include the Texas species and other sphaeromatids from hot springs in the American Southwest and Mexico: Exosphaeroma dugesi (Dolffus, 1893) from Aguascalientes, Mexico, and E. thermophilum (Richardson, 1897) from Socorro, New Mexico.Supported by National Park Service Contract PX 7000 3 0502, awarded to Owen T. Lind, Baylor University.     

Nerocila benrosei n. sp. (Isopoda: Cymothoidae), an external parasite of hogfishes from the northern Bahamas

Nerocila benrosei n. sp. is described from the hogfish, Lachnolaimus maximus (Walbaum), and the Spanish hogfish, Bodianus rufus (Linnaeus), (Perciformes: Labridae) from the northern Bahamas. Nerocila benrosei differs from all species of Nerocila by having the body of females 1.4-1.9 times as wide as long, instead of 2.0-3.0 times, and pleopods 1 and 2 lacking accessory lamellae. It differs from the only species of Nerocila with which it overlaps geographically, N. lanceolata (Say, 1818), by having the lateral margins of pleonites 1-5 strongly produced ventrally, coxae 5-7 manifestly shorter than the posterolateral projection of the respective pereonite, and a vaulted dorsal surface. The species of Nerocila in the northwestern Atlantic have almost mutually exclusive geographic ranges: New England to Panama, including Bermuda and the northern coast of Cuba (Nerocila lanceolata); Brazil to Trinidad and Tobago (Nerocila fluviatilis Schi?dte and Meinert, 1881); and the northern Bahamas and Bermuda (Nerocila benrosei). No species of Nerocila have been reported from the insular Caribbean. Nerocila benrosei appears to be highly host and site specific.     

Hemocyanin in Oniscus asellus (Isopoda)

• 1.1. An immunological crossreactivity, as demonstrated by Western blotting, exists between O. asellus hemocyanin and anti-keyhole limpet (Megathura crenulata) hemocyanin.
• 2.2. Using the anti-keyhole limpet hemocyanin, the presence of hemocyanin was detected in the hepatopancreas.
• 3.3. The amino acid composition of the hemocyanin of O. asellus was found to be similar to that of other isopods.

     

Occurrence of the internal parasite Portunion sp. (Isopoda: Entoniscidae) and its effect on reproduction in intertidal crabs (Decapoda: Grapsidae) from New Zealand

The parasite fauna of 4 intertidal grapsid crabs from New Zealand was studied between 1998 and 2000. The occurrence of an undescribed entoniscid species, Portunion sp. (Isopoda: Epicaridea), is presented. Portunion sp. was found in Cyclograpsus lavauxi (34.1%, n = 1650), Hemigrapsus crenulatus (19.0%, n = 2300), and Helice crassa (11.6%, n = 825) but was absent from Hemigrapsus sexdentatus (n = 636). Parasitized hosts contained mostly 1 female Portunion sp. but occasionally up to 7 females were found. One to 3 dwarf males typically occurred on each mature female Portunion sp. Most developmental stages of female Portunion sp. were found throughout the year, demonstrating that reproduction and infection occurred continuously. Portunion sp. differentially affected male and female hosts. Prevalence was generally higher in male hosts than in female hosts and increased significantly with host size. Female hosts were castrated, whereas males were not. Portunion sp., therefore, influenced the operational sex ratio in its host species, causing a more male-biased ratio.     

Cellular and biochemical response to Cr(VI) in Stenotrophomonas sp.

Chromium (Cr)-resistant bacteria isolated from a soil with 6 g kg⁻¹ of Cr were identified based on 16S rRNA gene sequence analysis as a Stenotrophomonas , and designated as JD1. Growth of JD1 was accompanied by transformation of Cr(VI) to Cr(III) in liquid medium initially containing 300 mg L⁻¹ Cr(VI), the maximum concentration allowing growth. JD1 produced the highest levels of a Cr(VI)-binding exopolysaccharide when grown in medium with 100 mg L⁻¹ Cr(VI). The relative exopolysaccharide monosaccharide composition was analysed by HPLC, which showed that rhamnose+galactose was the major component, and that its relative level increased when cells were grown with Cr(VI). JD1 grew as a biofilm on various inert surfaces. Biofilm macromolecular composition analysis indicated that the relative levels of exopolysaccharide and protein were more abundant in biofilms grown in 100 mg L⁻¹ Cr(VI), whereas relative uronic acid levels remained constant. Biofilm cells exposed to Cr(VI) were elongated, grouped in clusters and exopolysaccharide obtained from the biofilm extracellular matrix had an enhanced capacity to bind Cr(VI). Exopolysaccharide production and composition, and biofilm growth are discussed as a mechanism of protection that allows survival during Cr(VI) stress.     

Gnathia gurjanovae sp. n., a new species of Gnathiids (Isopoda: Gnathiidae) from Peter the Great Bay, Sea of Japan

A new species of isopods of the suborder Gnathiidae, Gnathia gurjanovae sp. n. has been described from Peter the Great Bay, Sea of Japan. The new species is most similar to G. derzhavini Gurjanova, 1933, but differs from the latter in a series of morphological characteristics of the male: frontal margin of the head bears a well-pronounced mediofrontal process; each mandible has an unarmed carina and an obscure tooth; pereopod 6 is relatively smooth; the basis, ischium, and merus of pereopod 4 bear strong spurlike processes.