Blunt Anterior End Research Articles

Molecular data and phylogenetic analysis of Myxobolus pseudonobilis n. sp. infecting the gill filaments of silver carp, Hypophthalmichthys molitrix Valenciennes, 1844.

In the present study, we combined morphological and phylogenetic methods to characterize Myxobolus pseudonobilis n. sp. infecting Hypophthalmichthys molitrix Valenciennes, 1844 from Chongqing, China. The morphology and molecular characteristics of M. pseudonobilis n. sp. were distinct from those of other previously described Myxobolus species. Mature myxospores were ovoid in frontal view with spore dimensions of 10.0±0.4 (9.3-10.9) μm in length and 8.5±0.2 (7.9-9.0) μm in width. Two polar capsules occupying approximately half of the myxospore length were unequal in size. The larger polar capsule containing 6 to 7 filament coils measured 5.2±0.3 (4.5-5.8) μm in length and 3.6±0.2 (3.2-3.9) μm in width, while the smaller capsule with 4 to 5 filament coils measured 3.9±0.3 (3.0-4.4) μm in length and 2.5±0.3 (2.1-3.6) μm in width. The comparison of molecular characteristics demonstrated similarities and genetic distances of 18S rDNA sequences of 95.19% - 98.20% and 1.82% - 5.46%, respectively, between M. pseudonobilis n. sp. and its morphologically similar species, and secondary structures were also distinctly different. Moreover, phylogenetic analysis showed that M. pseudonobilis n. sp. was clustered with other myxobolids possessing spores with a blunt anterior end and branched independently. In addition, the morphology of myxosporeans as an important indicator was discussed.

Two new species of Ichthyosaurus from the lowermost Jurassic (Hettangian) of Somerset, England

AbstractAll specimens of Ichthyosaurus from the Lower Jurassic of Somerset were previously identified as I. communis, an abundant and extremely variable species. Here, two new species of Ichthyosaurus are recognized from multiple specimens. The species are assigned to Ichthyosaurus on the basis of the humerus, pectoral girdle and forefin morphologies. I. larkini sp. nov. is distinguished by a broad jugal with a blunt anterior end that extends as far forward as the middle of the external naris, separating the maxilla and lacrimal; and a unique combination of other features. I. somersetensis sp. nov. is distinguished by a jugal with a nearly straight dorsal ramus that lacks a right‐angle dorsal bend; a high, narrow, crescentic postorbital that forms almost all of the posterior margin of the orbit and separates the jugal dorsal ramus from the orbit; and an ilium that is wide relative to its length, more oblong than rib‐like. The identifications are supported by a phylogenetic analysis which finds the new species more closely related to each other than to other species of the genus. We also identify a squamosal in both species, which confirms that it is present in the genus. This study suggests that hindfin morphology has some taxonomic utility, at least within the genus. The new species increases the diversity of Ichthyosaurus to six species, three of which are found in the Hettangian of Somerset.

Description and phylogeny of a new prostomatid, Metacystis similis nov. spec. (Protista, Ciliophora) from the East China Sea

The living morphology and infraciliature of a new marine prostomatid, Metacystis similis nov. spec., have been observed and investigated. Based on both morphological and molecular biological data, several closely-related and easily confused taxa were compared. The diagnosis for this new taxon: cylindrical marine Metacystis with a slightly blunt anterior end, in vivo 50-70 x 18-23 μm; body not loricate, uniformly cinctured by 16-18 transverse rings of cilia, which are also arranged in 32-36 longitudinal kineties; oral apparatus consisting of one circumoral dikinety and six girdles of densely packed monokinetids; single spherical macronucleus located in the center of the body; caudal region possessing one transparent, protruding hemicycle terminal vacuole. Information concerning the small-subunit rRNA gene sequence of the new species was also provided.

Two new and one already known species of the genus Thelohanellus (Myxozoa: Myxosporea: Bivalvulida) parasitizing fresh water fishes in wetlands of Punjab, India

AbstractA study of parasites of freshwater fishes in Harike and Ropar wetlands of Punjab of India revealed the presence of two new and one already known myxozoan species belonging to the genus Thelohanellus Kudo, 1933 infecting gills and caudal fin of two carps and gall bladder of a catfish in the wetlands of Punjab, India. Plasmodia of the first species, T. lamelliformis sp. n. are found infecting primary gill lamellae of Catla catla (Hamilton, 1822) vern. thail, spores measure 10.27 × 4.9 μm, are elongate pyriform, tapering anteriorly in valvular view, having truncated anterior end and broad rounded posterior end. Shell valves are stained dark blue (with iron-haematoxylin) in the middle as well as in the posterior part of the spore body. Anteriorly, a prominent bent is present on one side of the shell valve. Polar capsule is broadly pyriform, measures 3.8 × 2.6 μm and is placed in the middle of spore body cavity with a distinct neck leading to the outside. Plasmodia of the second species, T. rohi sp. n. are found infecting caudal fin of Labeo rohita (Hamilton, 1822) vern. rohu, spores measure 14.5 × 7.7 μm, are elongately oval in valvular view having narrow, blunt anterior end with a prominent pore and broad rounded posterior end. A knob-like structure is present at the anterior end of the spore. Inner valve stains dark-blue (with iron-haematoxylin) in the middle and posterior part of the spore body. Polar capsule is oval to spherical in shape, measures 5.5 × 4.7 μm, is placed anteriorly and occupies nearly one third of the spore body cavity. Plasmodia of the third species, T. wallagoi Sarkar, 1985 infect primary gill lamellae of Wallago attu (Bloch & Schneider, 1807), spores measure 8.2 × 4.1 μm, are pyriform in valvular view, having bluntly pointed anterior end and rounded posterior end. Parietal folds are absent. Polar capsule is pyriform, measures 3.3 × 1.67 μm, is eccentrically placed with narrow pointed anterior end. Earlier, this species was reported from West Bengal infecting gall bladder of Wallago attu.

Two new and two already known species of genus Thelohanellus Kudo, 1933 (Myxozoa: Myxosporea: Bivalvulida) infecting Indian major carp fishes in Punjab wetlands (India)

A survey of parasites of freshwater fishes in Harike, Kanjali and Ropar wetland of Punjab (India) revealed the presence of two new and two already known myxosporean species belonging to the genus Thelohanellus Kudo, 1933 parasitizing fins and gills respectively. Spores of the first species, T. kalavatae n. sp. measure 11.5×4.9μm, elongately oval in valvular view having rounded blunt anterior end and rounded posterior end with lateral walls almost parallel to each other. Polar capsule is globular in shape and measure 5.2×3.3μm in size. Anterior end of the polar capsule terminate into a small distinct neck. Spores of the second species, T. kalbensi n. sp. measure 9.5×4.9μm, egg shaped to ovoid in valvular view having narrower anterior end with a prominent pore and broad rounded posterior end. Polar capsule is globular in shape with a short distinct tubular neck, measure 4.8×3.16μm and occupies almost two-third of the spore body cavity. Spores of third species, T. avijiti Basu and Haldar, 2003 measure 10.1×6.6μm, egg shaped in valvular having tapering, bluntly pointed anterior end and broad rounded posterior end. Polar capsule is rounded to sub-spherical in shape, measure 3.3×3.0μm and is situated anteriorly. Spores of fourth species, T. gangeticus Tripathi, 1952 measure 13.3×4.8μm, elongately pyriform in valvular view having tapering anterior end and rounded posterior end. Polar capsule is also elongately pyriform in shape measure 6.6×3.1μm with thin neck and occupy half of the spore body cavity.

Two new species of Myxobolus (Myxozoa:Myxosporea:Bivalvulida) from freshwater fishes of Punjab wetlands (India)

During the present study two new species were collected from mucous membrane around gill lamellae of Puntius sophore (Ham.) vern. chittal and Cirrhina mrigala (Ham.) vern. mrigal from Harike Wetland, Punjab respectively. Spore of the first species i.e. Myxobolus chittalii are histozoic, pear shaped with characteristic nipple-like anterior end and rounded posterior end. They measure 9.0×6.18μm. Polar capsules are two, equal, measuring 4.5×2.4μm, pyriform with bluntly pointed anterior end and rounded posterior end. They are placed posteriorly from the tip of the spore and are parallel to each other in the spore body cavity. A prominent, tongue shaped intercapsular process is present. Spores of the second species i.e. M. mehlhorni are histozoic, oval to egg in shape having narrow, blunt anterior end and broad rounded posterior end, measure 8.9×6.8μm. Shell valves smooth, symmetrically thin, measure 0.5μm in thickness. Parietal folds are absent. Polar capsules two, prominently unequal, placed anteriorly and converge towards the anterior end. Both polar capsules are flask-shaped with anterior end having a prominent neck. The larger polar capsule measure 3.7×2.5μm occupying less than half while the smaller one measure 2.6×1.5μm and occupy less than one-third of the spore body cavity. An intercapsular process is absent.

Two new species of Myxobolus (Myxozoa: Myxosporea: Bivalvulida) infecting Indian freshwater fishes in Punjab Wetlands (India)

A survey of parasites of freshwater fishes in Harike and Ropar Wetlands of Punjab (India) revealed the presence of two new myxosporean species belonging to the genus Myxobolus Butschli 1882. Spores of the first species, M. duodenalis sp. nov. parasitize the inner wall of the duodenum of Wallago attu (Bloch and Schneider) (Cypriniformis: Cyprinidae) vern. mulli are characterized by a broad, pyriform shape with a blunt anterior end and measures 9.0 × 3.20 μm. Spore valves are thin, smooth, and symmetrical with no parietal folds. There are two polar capsules, prominently unequal and pyriform in shape, with a narrow anterior end and a rounded posterior end. The larger polar capsule measures 4.70 × 1.76 μm and the smaller 2.76 × 1.06 μm. The larger polar capsule occupies more than half, while the smaller one occupies one third of the spore body cavity. An intercapsular process is absent. Spores of the second species, Myxobolus patialensis sp. nov. parasitize the caudal fin of Labeo rohita (Ham. 1822) (Cypriniformis: Cyprinidae) vern. rohu are pyriform in valvular view, measuring 11.28 × 6.67 μm. The two shell valves are asymmetrical and contain five parietal folds along the posterior end of the spore. Two anteriorly situated polar capsules, elongated and oval in shape are prominently unequal in size. The larger polar capsule measures 4.8 × 3.1 μm and smaller one 1.70 × 1.51 μm. The larger polar capsule lies obliquely to the spore axis and the smaller one is at the same level but pointing outward anteriolaterally. An intercapsular process is absent. This species is characterized by having a prominent ridge on the shell surface anteriolaterally on the side of the smaller polar capsule.

The LobopodOnychodictyonfrom the Lower Cambrian Chengjiang Lagerstätte Revisited

Onychodictyon ferox, from the Lower Cambrian Chengjiang Lagerstatte, is a worm-like armored lobopod with 10 pairs of dorsal plates and a pair of probable sensory appendages (“antennae”). Newly discovered complete specimens show that Onychodictyon is represented by two species: O. ferox with a “head” bearing a pair of dorsal “antennae” and a trunk with 11 pairs of limbs, whereas O. gracilis has a blunt anterior end without any appendages and a trunk with 12 pairs of limbs. Because of the close resemblance of the “antennae” of O. ferox and those of the lobopod Miraluolishania, they are considered to be homologous structures. The “antennae” of Cambrian lobopodians are proposed to be homologous with the arthropod antennulae.

Steinernema sichuanense n. sp. (Rhabditida, Steinernematidae), a new species of entomopathogenic nematode from the province of Sichuan, east Tibetan Mts., China

Steinernema sichuanense n. sp. is characterized by male, female and IJ. For male, the spicules are robust with prominent rostrum; gubernaculum has blunt anterior end; cuneus is arrow-shaped, pointed posteriorly. Second-generation male has a prominent mucron. For female, tail usually has one to four papillae-like projections on tail tip; post anal swelling is absent. For IJ, body length is about 710 μm; lateral field has six ridges; the formula of lateral field is 2, 5, 6, 4, 2 with two prominent submarginal ridges; tail usually has a dorsal depression. In Steinernema affine/intermedium group, the IJ of S. sichuanense n. sp. differs from S. affine by its absence of the internal tail spine; differs from Steinernema beddingi by its six ridges in lateral field compared to 4 for S. beddingi. For male mucron is absent in both generations of S. affine, S. intermedium and S. beddingi, whereas it is present in the second-generation of S. sichuanense sp. n. Morphology and morphometrics of spicules and gubernacula of the four species in S. affine/ intermedium group are quite different based on SEM photographs. For female, the postanal swelling is absent in the first-generation of S. sichuanense n. sp. whereas S. affine and S. intermedium have slight swelling and S. beddingi has conspicuous swelling. The new species is further recognized by characterization of sequences of ITS and D2/D3 regions of the ribosomal DNA. The symbiotic bacterium associated to S. sichuanense belongs to the species Xenorhabdus bovienii.

Chromadoridae (Chromadorida: Nematoda) from the Indian Ocean: Description of new and known species

Seventeen new and known species of the familyChromadoridae are described. The genus Dichromadora is represented by five species. Dichromadora longicaudata sp.n. is characterised bya slender body and thin long tail; Dichromadoragathuai sp.n. is characterised by a blunt anteriorend, a raised lateral alae and a gubernaculum that isserrated on the posterior end; D. loiseae sp.n.is characterised by a blunt anterior end with a raisedcollar, double bulb, spicules with a poorly developedcapitulum and seven pre-cloacal supplements; D.cucullata, Lorenzen, 1973 is characterised by lateraldifferentiation of two (four?) longitudinal rows ofdots, seven pre-cloacal supplements and spicules witha rounded capitulum that is open at the tip; D.quadripapillata sp.n. is characterised by acylindrical body with an elongate tail end, two(four?) longitudinal rows of dots, anterior pharyngealregion with two pairs of setae, spicules with poorlydeveloped capitulum and four (1+3) pre-cloacalsupplements.

Further observations on the sporogony of Eimeria sardinae in the testis of the herring Clupea harengus L.

Sporocyst formation commences with division of the sporoblast nucleus, after which two sporozoites develop, one at each end of the sporoblast. A thickening beneath the limiting unit membrane of the sporoblast is the first indication of the sporozoite pellicle forming. This subsequently develops into a cone-shaped structure, which becomes the anterior end of the sporozoite as it separates from the sporocyst residuum. The sporozoites elongate as they mature, and the sporocyst residuum, containing amylopectin and refractile granules, becomes smaller. A typical apical complex is present at the blunt anterior end of the sporozoite. A homogeneous area containing paracrystals is present in both the sporoblast and the sporozoite. There are no refractile granules in the sporozoite. The sporocyst wall is thin and contains no mechanism for releasing the sporozoite, such as a Stieda body or suture.

Scanning Electron Microscopic Observations of the Oocyst, Sporoblast and Sporozoite of Plasmodium yoelii yoelii

Scanning electron microscopy was used to study the surface characteristics of the oocyst, sporoblast and sporozoite of Plasmodium yoelii yoelii. Observations were made of the sporogonic stages of 6-12 day infections of the malaria parasite in Anopheles stephensi. Oocyst and sporoblast development were not synchronous. The surface of the undifferentiated (early stage) oocyst appeared smooth, whereas that of differentiated (late stage) oocysts were rough or wrinkled. The wall of the differentiated oocysts showed numerous micropores at higher magnification (x15,000-20,000) the biological significance of which is not known. Small, bud-like satellite bodies were seen attached to some oocysts. Various forms of different stages of the sporoblast were described. Sporozoite budding took place on the surface of the sporoblast body. The sporozoite was elongate, curved and with a blunt anterior end.

The Egg‐shell of the Cabhage Root Fly, Erioischia brassicae (Bouché)

SUMMARYThe electroscan microscope was used to show details of the external structure of the egg of cabbage root fly. The median area between the hatching lines differs from the more solid structure of the longitudinal ridges on the rest of the surface. On the pointed posterior end are small holes in the outer layer, but in contrast to wheat bulb fly, Leptohylemyia coarctata (Fall.), there are no distinct plastron areas around the micropyle at the blunt anterior end. The egg of cabbage root fly also lacks small plastron areas among the longitudinal ridges.

The fine structure of the sporozoite of Lankesteria culicis.

SYNOPSIS. The sporozoite of Lankesteria culicis was studied by light and electron microscopy, after excystation in the intestine of Aedes aegypti 1st stage larvae. The sporozoite was 9.5–10.0 μ long with a blunt anterior end and a tapered posterior region. The organism was enclosed by a typical pellicle consisting of an outer and an inner membrane with underlying subpellicular microtubules. The anterior end had a conoid with 2 associated rings, a polar ring which served as a termination of the subpellicular microtubules and a flask‐shaped structure situated internal and posterior to the conoid. A micropyle consisting of a collar formed from the inner membrane and lacking an invagination of the outer membrane was present near the anterior end of the parasite. The nucleus was centrally located and had a peripheral concentration of chromatin and a central nucleolus. One or more mitochondria were observed in the vicinity of the nucleus.

Ascospore form

In most Ascomycetes the lower part of the ascospore is the mirror image of the upper. In many species, however, the upper part is relatively broad and blunt, and the lower narrow and pointed. The reverse arrangement never appears to occur. Possible biological advantages of the ascospore with blunt anterior end and more tapered posterior one are discussed.