Marginal Groove Research Articles

The Ixodes ricinus complex (Acari: Ixodidae) in the Southern Cone of America: Ixodes pararicinus, Ixodes aragaoi, and Ixodes sp. cf. I. affinis.

The goal of this study was to clarify the taxonomic status of the Ixodes ricinus complex in the Southern Cone of America, by using morphological characters and molecular markers (mitochondrial 16SrDNA and cox1 genes). The morphological analysis indicates that three different taxa of the I. ricinus complex occur in this region: Ixodes pararicinus, Ixodes aragaoi, and Ixodes sp. cf. I. affinis. The most prominent diagnostic character among them is the size of scutal punctations in both male and female ticks. In the males of Ixodes sp. cf. I. affinis, the punctations on the central field and along the median marginal groove of the scutum are clearly larger than in the males of I. aragaoi and I. pararicinus, while the punctations of I. aragaoi are larger but less numerous than in I. pararicinus. The punctations in Ixodes sp. cf. I. affinis females are larger and deeper than in females of I. aragaoi and I. pararicinus, and those of I. aragaoi are slightly larger than in I. pararicinus. The length of the lateral posterior denticles of the male hypostome is comparatively longer in I. aragaoi than in the other two species, and longer in Ixodes sp. cf. I. affinis than in I. pararicinus. In the 16S analysis, I. pararicinus and I. aragaoi are monophyletic (99% and 98% bootstrap support, respectively), while Ixodes cf. I. affinis does not represent a single lineage. In the cox1 analysis, both I. pararicinus and I. aragaoi are well-defined taxa, but the bootstrap support for Ixodes sp. cf. I. affinis is low (67%). In general, there are considerable 16SrRNA differences among lineages of Ixodes sp. cf. I. affinis from different geographical areas. These results may be indicative of the existence of different species. The populations morphologically compatible with I. affinis from Argentina, Colombia, Panama, Belize, and USA should be provisionally named as Ixodes sp. cf. I. affinis until an integrative taxonomic work with further evidence redefines whether or not this taxon actually represents a species complex.

Rhipicephalus sanguineus (Latreille, 1806): Neotype designation, morphological re-description of all parasitic stages and molecular characterization

The aims of this work were to re-describe all parasitic stages of Rhipicephalus sanguineus sensu stricto, to select and deposit a neotype, and to characterize some of its diagnostic molecular traits. A male of R. sanguineus s.s. collected in Montpellier, France, was designated as neotype. The diagnostic characters unique to the male of R. sanguineus s.s. are: spiracular plate elongated and subtriangular in shape with a dorsal prolongation narrow and usually visible dorsally, with the dorsal prolongation narrower than the width of the adjacent festoon; punctations of the scutum moderate in number and unequal in size; marginal groove conspicuous, deep and punctate; posteromedian groove distinct and elongated, and posterolateral grooves often sub-circular, shorter than posteromedian groove; adanal plates long, wide, and subtriangular in shape, with a clear concavity in its inner margin and posterior margin broadly rounded or truncated; accessory adanal plates with the posterior end pointed, narrower than the width of adjacent festoon. The female of R. sanguineus s.s. can be diagnosed by a combination of broadly U-shaped genital aperture, spiracular plate with a narrow dorsal prolongation visible dorsally, basis capituli hexagonal with broad lateral angles, and scutum barely longer than broad with posterior margin sinuous and punctations moderate in number and unequal in size, larger and more numerous along cervical fields. The nymph has a basis capituli sub-triangular dorsally with lateral angles slightly curved and presence of ventral processes, scutum approximately as long as broad with lateral margins nearly straights, posterior margin broadly rounded, and cervical grooves short and sigmoid in shape extending posteriorly to the level of the eyes. The larva is characterized by basis capituli broader than long with lateral angles short and slightly curved and with posterior margin slightly convex, cervical grooves short, shallow and subparallel, and scutum almost twice broader than long. The phylogenetic analysis of DNA sequences support R. sanguineus s.s. as a well-defined taxon when compared with other species of the R. sanguineus group: R. turanicus s.s., R. camicasi, R. guilhoni, R. sulcatus, R. pusillus, R. rossicus and R. leporis. Molecularly R. sanguineus s.s. also encompasses the so-called “temperate lineage” from the New World (Argentina, southern Brazil, Chile, Uruguay, and USA). The evidence currently available supports the presence of R. sanguineus s.s. in Europe (France, Italy, Spain, Switzerland and Portugal) and America (Argentina, Brazil, Chile, Uruguay and U.S.A.), but further studies are needed to determine the exact geographic range of this taxon.

A new species of Microhyla Tschudi, 1838 (Anura: Microhylidae) from West Coast of India: an integrative taxonomic approach.

A new species of microhylid frog Microhyla kodial sp. nov. from the west coast of India is described in this paper. It is distinct from all described species of Microhyla occurring in South and Southeast Asia as revealed by a combination of morphological, molecular and acoustic characters. The new species is characterized by absence of lateral body stripe, tuberculated dorsal skin surface, absence of webbing between fingers, presence of basal webbing between toes and absence of dorsal marginal groove on finger and toe disc. Each male advertisement call lasts for 0.11-0.42 s and is comprised of 2-7 pulses with a dominant frequency of 3.3-4.2 kHz. The breeding season is short, limited to the rainy season (June to September) and the females lay up to 300 eggs per clutch. A molecular phylogenetic tree constructed using the mitochondrial 16S rRNA gene shows that M. kodial sp. nov. is closely related to the M. achatina group from Southeast Asia. The uncorrected genetic divergence between the new species and its closest congeners M. heymonsi, M. mantheyi, M. borneensis and M. orientalis were 7.3-7.6 %, 7.5-7.8%, 7.8-8.1% and 8.1-8.4% respectively. At present, this species is known only from the type locality, a highly disturbed urban and industrialized area which needs conservation intervention.

Description of a new species of Amblyomma Koch, 1844 (Acari: Ixodidae), parasite of deer (Artiodactyla: Cervidae) and wild pigs (Artiodactyla: Suidae) in the Philippines.

Amblyomma anicornuta n. sp. (Acari: Ixodidae) is described based on adults and nymphs ex deer (Artiodactyla: Cervidae) and wild pigs (Artiodactyla: Suidae) from Luzon, Philippines. Adults of A. anicornuta n. sp. are similar to those of several Asian and Australasian species of Amblyomma Koch, 1844 with a 4/4 dental formula on the hypostome but can be distinguished by the colouration and pattern of punctations on the conscutum in the male and scutum in the female, the absence of a marginal groove on the conscutum in the male, the possession of long, thick, prominent setae on the alloscutum in the female, projections on anal valves and sclerotised ring around them in the male, a large median sclerite ventrally in the male, as well by the shape of the genital aperture in the female and the size and shape of spurs on coxae I-IV in both sexes. The nymph of A. anicornuta n. sp. is somewhat similar to that of A. babirussae Schulze, 1933 and A. geoemydae (Cantor, 1847) but can be distinguished by the colouration pattern on the scutum, the presence of dorsal cornua and the size of the spurs on coxae I-IV.

Morphological features of Ixodes persulcatus and I. ricinus hybrids: nymphs and adults.

Our aim was to reveal morphological features of first-generation Ixodes persulcatus and I. ricinus hybrids (nymphs and adults) obtained under laboratory conditions for further study of natural populations of these species in sympatry foci. In 65 nymphs of three groups I. ricinus (23 specimens), I. persulcatus (21 specimens), and hybrids (21 specimens), 16 parameters were evaluated (length/width of the scutum and capitulum, length of the hypostome, palp, tarsus I, coxa I, sternal setae, and various scutal and alloscutal setae) and discrimination analysis was performed allowing differentiation of hybrid nymphs from original species. General effectiveness of classification of I. ricinus, I. persulcatus, and hybrids was >95%. Discriminant functions are presented allowing classification of I. persulcatus, I. ricinus, and hybrid nymphs. For description of morphology, 27 adult hybrids (13 males and 14 females) were examined under a stereo microscope at 14-28× (without preparation of permanent mounts). The following morphological distinctions of hybrids from original species were described: posterior marginal groove is not clear (as in I. ricinus) and absence of syncoxa on coxa I (as in I persulcatus). In hybrid males, simultaneous absence of syncoxa on coxa I (as in I. persulcatus) and a long internal spur on coxa I (as in I. ricinus) can be used as a diagnostic feature. Based on the detected characteristics, 10 of 157 ticks collected in Karelia in I. ricinus and I. persulcatus sympatry area were classified as hybrids.

Passipassalus brevicornis n. sp.: a New Passalidae (Coleoptera) from Brazilian Amazonian, with a Key to the Species of Passipassalus Reyes-Castillo & Fonseca.

Passipassalus brevicornis n. sp. is described from two specimens from Tefé and Coari, Amazonas, Brazil. This species represents the fifth species recognized of Passipassalus and differs from the other species of the genus mainly by having an apex of central tubercle of median frontal structure not free, frontal fossae with some scarce setae, metasternal fossae with scarce setae, humeri fully pubescent, and marginal groove over anterior ventral edge of femur I marked and complete. Additionally, a key to the species of Passipassalus is given.

Cambrian cinctan echinoderms shed light on feeding in the ancestral deuterostome.

Reconstructing the feeding mode of the latest common ancestor of deuterostomes is key to elucidating the early evolution of feeding in chordates and allied phyla; however, it is debated whether the ancestral deuterostome was a tentaculate feeder or a pharyngeal filter feeder. To address this, we evaluated the hydrodynamics of feeding in a group of fossil stem-group echinoderms (cinctans) using computational fluid dynamics. We simulated water flow past three-dimensional digital models of a Cambrian fossil cinctan in a range of possible life positions, adopting both passive tentacular feeding and active pharyngeal filter feeding. The results demonstrate that an orientation with the mouth facing downstream of the current was optimal for drag and lift reduction. Moreover, they show that there was almost no flow to the mouth and associated marginal groove under simulations of passive feeding, whereas considerable flow towards the animal was observed for active feeding, which would have enhanced the transport of suspended particles to the mouth. This strongly suggests that cinctans were active pharyngeal filter feeders, like modern enteropneust hemichordates and urochordates, indicating that the ancestral deuterostome employed a similar feeding strategy.

A New Species ofRhipicephalus(Acari: Ixodidae), a Parasite of Red River Hogs and Domestic Pigs in the Democratic Republic of Congo

A new tick species belonging to the genus Rhipicephalus Koch, 1844 (Acari: Ixodidae), namely, Rhipicephalus congolensis n. sp., is described. Males and females of this species are similar to those of Rhipicephalus complanatus Neumann, 1911 and Rhipicephalus planus Neumann, 1907, but it can be distinguished from them by a pattern of dense medium-sized punctations on the conscutum and scutum. Males of R. congolensis may be distinguished by the following characters: posterior half of the marginal groove deep with a sharp outer edge; anterior portion of the groove shallow with rounded edges; posteromedian groove distinct, long, and deep; adanal plates broadly sickle-shaped; bluntly pointed posteromedian spur on coxa I; and posterolateral spur on coxa I slightly longer or subequal to posteromedian spur. Females of R. congolensis may be distinguished by the following characters: outer edge of cervical grooves smooth and not clearly defined either by slope or punctations; genital aperture broad, bowl-shaped, and tripartite in appearance, with central flap flanked on either side by an oval depression; and posteromedian spur on coxa I tapering to its apex. R. congolensis is known only from the Democratic Republic of Congo, where the adults were collected from red river hogs, Potamochoerus porcus (L.), and domestic pigs, Sus scrofa (L.), within the dense equatorial forest in the districts of Equateur and Tshuapa, in the province of Equateur.

Traces of Augoichnus dituberculatus gen. et sp. nov. on Hypermorphocrinus magnospinosus from the Lower Permian of Cisuralia

Traces of Augoichnus dituberculatus on Hypermorphocrinus magnospinosus and some other crinoids are described from the reef deposits of the Sarginian Horizon near the village of Ryabinovka, in the vicinity of Krasnoufimsk. Usually these are groups of shallow depressions, egg-shaped in outline, 4–5 mm long, similarly oriented, with a marginal groove, paired tubercles, and a deeper subcentral region. Less commonly the depressions are deep and occasionally even can perforate the skeleton. It is possible that these traces were left by gastropods, which could have moved on the surface of crinoids and fed at their expense.

Estimation of the biological age in females of the Taiga tick Ixodes persulcatus by changes in the body shape and the surface of the integument

A method of visual estimation of the biological age of living hungry tick females by visible changes in the depth of the marginal groove and the structure of the alloscutum cuticle during natural ageing is developed. In recently activated individuals, the body is convex and the marginal groove is exposed, demonstrating distinctly visible cuticular microfolds. In attenuated ticks, the body is flattened and the marginal fold overlays the marginal groove, concealing cuticular microfolds.

A new genus of hard ticks in Cretaceous Burmese amber (Acari: Ixodida: Ixodidae).

A hard tick larva in Cretaceous Burmese amber is described as Cornupalpatum burmanicum n. g., n. sp. Diagnostic characters include a subcircular body with a marginal groove, 11 festoons, elongate four-segmented palpi with the fourth segment distinct and apical, the absence of an anal groove and eyes, and the presence of claws on palpal segment 3. The last character is unique for all members of the Ixodida, both fossil and extant. Aside from the palpal claws and marginal groove, features of the tick larva closely resemble those of members of the genus Aponomma Neumann 1899, considered one of the most primitive tick lineages today, whose hosts are primarily reptiles.

Particle transport in the zebra mussel, Dreissena polymorpha (Pallas).

The capture, transport, and sorting of particles by the gills and labial palps of the freshwater mussel Dreissena polymorpha were examined by endoscopy and video image analysis. More specifically, the morphology of the feeding organs in living zebra mussels was described; the mode and speeds of particle transport on the feeding organs was measured; and the sites of particle selection in the pallial cavity were identified. Particle velocities (outer demibranch lamellae, 90 microm s(-1); inner demibranch lamellae, 129 microm s(-1); marginal food groove of inner demibranchs, 156 microm s(-1); dorsal ciliated tracts, 152 microm s(-1)), as well as the movement of particles on the ctenidia and labial palps of D. polymorpha, are consistent with mucociliary, rather than hydrodynamic, transport. Particles can be sorted on the ctenidia of zebra mussels, resulting in a two-layer transport at the marginal food groove of the inner demibranch. That is: preferred particles are transported inside the marginal groove proper, whereas particles destined for rejection are carried superficially in a string of mucus. Sorting also occurs at the ventral margin of the outer demibranch; desirable particles are retained on the outer demibranch, whereas unacceptable particles are transferred to the inner demibranch and ultimately excluded from ingestion. We suggest that the structure of homorhabdic ctenidia does not preclude particle sorting, and that some ecosystem modifications attributed to zebra mussels may ultimately be due to ctenidial sorting mechanisms.

The classification and evolution of pollen types ofPlanchonioideae (Lecythidaceae)

The pollen type ofPlanchonioideae is unique among the angiosperms in its syntricolpatism associated with the marginal ridge, marginal groove, and polar cushion; it has been studied byJ. Muller, who classified it into three types, mainly with a light microscope. In the present study, pollen grains of the six constitutent genera were studied with a scanning electron microscope, five additional pollen types were recognized. Of the eight pollen types the one with sealed polar ectoapertures and weakly developed marginal ridges, without marginal grooves and polar cushions is regarded as the most primitive. Evolutionary trends proceeded with the opening of the polar ectoapertures, the complication of the polar cushions and marginal grooves. In the most advanced form, the marginal ridges and marginal grooves coalesced to form two concentric rings, whereas the polar cushions were secondarily reduced.

In Vivo Observations of Larval Brooding in the Chilean Oyster, Ostrea chilensis Philippi, 1845.

The Chilean oyster Ostrea chilensis broods its larvae within the mantle cavity. In vivo observations, made with an endoscope, have demonstrated that the female does not undergo gill modification before or during the brooding process. The veliger larvae move freely, have no physical connections with the tissues of the mother, and are often seen as an aggregation ("swarm") around the labial palps. The larvae show a distinct circulation pattern inside the mantle cavity of the mother. Sporadic but strong pallial currents eject larvae from the swarm and transport them between the demibranchs to the posterior region, from which some return anteriorly in the basal ciliated tracts of the gills, and others on the marginal ciliated grooves. Larvae frequently move from the basal to the marginal groove of a demibranch via the ordinary filaments, although they occasionally travel in the opposite direction, moving along the principal filaments from the marginal groove to the basal tract. The circulation of the larvae in the mantle cavity may serve to irrigate them, thereby facilitating gas exchange and suspension-feeding. The veligers are not lecithotrophic, but readily remove and ingest particles suspended in the mantle cavity. The impact on the nutrition of the mother is not yet known, although the presence of particles in the food grooves and tracts and the transfer of material to the palps suggest that the feeding mechanism functions normally during brooding.

SEM Evidence for a New Species, Giardia psittaci

The genus Giardia has been subdivided by Filice (1952) into 3 species, G. agilis, G. muris, and G. duodenalis, based on the morphology of the median body and subtle variations in the dimensions of trophozoites. Giardia trophozoites were isolated from the small intestine of budgerigars (parakeets) and examined morphologically with light and scanning electron microscopy. These trophozoites, like other Giardia spp., possessed a flattened dorso-ventral shape, 8 flagella, and an adhesive disc on the ventral surface. The presence of a claw hammer-shaped median body suggested classification of these trophozoites as G. duodenalis. However, unlike any known members of G. duodenalis, the Giardia trophozoites from budgerigars were morphologically distinct in that they lacked the ventrolateral flange and therefore did not have a marginal groove bordering the anterior and lateral border of the adhesive disc. This distinct morphology clearly indicated that trophozoites from budgerigars should be considered as a separate species, G. psittaci. Our evidence has demonstrated that median body shape cannot serve as a sole criterion for speciation of Giardia. In addition, if other avian species of Giardia also resemble G. psittaci, then this would suggest that evolutionary divergence has occurred in the genus Giardia.

The histology and histochemistry of the pedal glandular system of two limpets,Patella vulgataandAcmaea tessulata(Gastropoda: Prosobranchia)

Patella vulgatapossesses nine different pedal glands, six of which pour their secretions on to the sole. Proteins secreted by the marginal gland into the marginal groove are used for locomotion, especially when the limpet moves off following a period of adhesion. Another protein-secreting subepithelial gland, sparsely present throughout the foot, is also believed to be used in locomotion. A third gland type is present in the epithelium of the sole. The secretion of these epithelial mucocytes which is a weakly acidic muco-polysaccharide (MPS) is likely to have a locomotory function. Three other sole glands secrete highly viscous acidic MPS. Their secretions are likely to have an adhesive function. The three other glands present in the foot are contained within the side-wall. Of these, two are believed to secrete mucus to protect the animal against desiccation during emersion; and the other, present only in youngP. vulgata, pours its acidic MPS secretion into the epipodial streak. This secretion consolidates debris before it is cleared from the pallial cavity; in adult animals, muscular contractions of the foot are powerful enough to clear debris without the help of the epipodial gland.InAcmaea tessulatathe six glands present open out on to the sole and correspond in position, composition and function to the six glands of the sole ofP. vulgata. There are no glands within the side-wall.

Form, habit and evolution in the chamidae (bivalvia) with reference to conditions in the rudists (hippuritacea)

Form, habit and evolution in the chamidae (bivalvia) with reference to conditions in the rudists (hippuritacea)

ULTRASTRUCTURE OF LAMBLIA DUODENALIS. I. BODY SURFACE, SUCKING DISC AND MEDIAN BODIES.

SYNOPSIS. The body surface, sucking disc and median bodies of Lamblia duodenalis have been studied on ultrathin sections in the electron microscope. The body is covered by a pellicle, displaying a striated structure in the area of the sucking disc. The striation is due to 150 Å thick dense ridges which are spaced in distances of 200–400 Å. The ridges are formed by the internal pellicular membrane and have a triangular cross section with a very dense apex. They are arranged concentrically and run parallel to the surface of the sucking disc lobes. Anteriad to the nuclei in the median line a space is free of ridges. The margin of the sucker is elevated above the body forming a sharp crest of the ridged pellicle.This crest is the inner wall of a marginal groove delimiting the sucker from the body. The outer margin is circumscribed by a fold in the body tapering to the posterior end. A ventral groove containing the two ventral flagella lies in the median line. The movement of the ventral flagella pushes the medium through the marginal and ventral grooves thus producing vacuum in the sucker area.The median bodies are composed of numerous 150 Å thick tubular fibrils. They differ in their ultrastructure from the parabasal apparatus in other flagellates and have nothing in common with the kinetoplasts. Their functional significance awaits elucidation.

On the Ciliary Mechanisms and Interrelationships of Lamellibranchs: PART I: New Observations on Sorting Mechanisms

ABSTRACT The gills of Solen marginatus, Ensis siliqua, and Ensis arcuatus are synaptorhabdic or eulamellibranchiate, and the lamellae plicate and heterorhabdic. The latero-frontal cilia are large; there are in addition small subsidiary laterofrontal cilia. The frontal cilia on the filaments forming the bottom of the plical grooves are fine and beat dorsally. In the two species of Ensis the frontal cilia on the filaments forming the sides and apices of the plicae are arranged in two tracts with the effective beat in opposite directions; in Solen marginatus in three tracts, a median one of coarse cilia beating ventrally and two outer ones of fine cilia continuously beating dorsally. In both genera the movement of particles in the plical grooves is dorsalward; on the crests mainly ventralward; on the sides of the plicae ventral or dorsal according apparently to their type and number. Along the marginal grooves of the demibranchs, between the bases of the two demibranchs of a gill, and along the dorsal edges of all the ascending lamellae, currents are towards the mouth. The gills of Cultellus pellucidus are synaptorhabdic or eulamelhbranchiate, and the lamellae flat and homorhabdic. The ventral edge of the outer demibranch is ungrooved. On the frontal surfaces of the filaments of both lamellae of the inner and the ascending lamella of the outer demibranch there are, in addition to fine cilia, a tract of long, coarse ones which beat ventrally. The fine frontal cilia, which alone are present on the descending lamella of the outer demibranch, beat dorsally, and, so far as could be ascertained, the tracts of fine cilia on the other three lamellae of the gill also beat dorsally. The obvious frontal currents are toward the ventral edge on both lamellae of the inner and on the ascending lamella of the outer demibranch, and dorsalward on the descending lamella of the outer demibranch. Along the marginal groove of the inner demibranch, between the bases of the two demibranchs of a gill, and along the dorsal edges of all the ascending lamellae, currents are towards the mouth.