Somatic Morphology Research Articles

A review of the genus Paratus Simon (Araneae, Dionycha)

The spider genus Paratus Simon, 1898 was known for more than hundred years from a single female from Sri Lanka. A survey of spiders in south China and northern India reveals two new species: P. sinensis sp. n. and P. indicus sp. n. Both species are described based on males and females. The study of the copulatory organs and somatic morphology led us to conclude that Paratus cannot be placed in any described subfamily of Liocranidae, where it was placed originally, or in Corinnidae. Therefore, we describe a new subfamily Paratinae subfam. n. and retain this group within Liocranidae.

Heterochrony during skeletal development of Pseudis platensis (anura, hylidae) and the early offset of skeleton development and growth

The aquatic frog Pseudis platensis has a giant tadpole, long developmental time, and dissociated metamorphic events that include later offset of larval somatic morphologies. Moreover, when the tadpole metamorphoses, the young frog is nearly the size of an adult, suggesting that this species has low rates of postmetamorphic growth. Herein, we study the development of the skeleton during larval development up to the end of metamorphosis, which is denoted by the complete lost of the tail in P. platensis. Our study revealed heterochronic differences in skeletal development compared with that of most anurans; these involve the complete differentiation of skull bones and the extensive ossification of the postcranial skeleton before completion of metamorphosis. The skull of metamorphosing P. platensis has an ossified sphenethmoid and a fully formed plectral apparatus, thus differing with regard to the pattern observed in most anurans in which both developmental events take place during the postmetamorphic life. Despite the fact that the iliosacral articulation and the urostyle are present at the end of metamorphosis as in most anurans, ossification/calcification of carpus, tarsus, and limb epihyses during metamorphosis of P. platensis suggests that the postcranial skeleton lacks postmetamorphic growth. This study also includes a discussion of the pattern of development of the plectral apparatus, which allows us to propose a new hypothesis regarding pars externa plectri homology.

Quantitative Chemical Composition of Cortical GABAergic Neurons Revealed in Transgenic Venus-Expressing Rats

Although neocortical GABAergic (gamma-aminobutyric acidergic) interneurons have been the focus of intense study, especially in the rat, a consensus view of the functional diversity and organization of inhibitory cortical neurons has not yet been achieved. To better analyze GABAergic neurons in the rat, we used a bacterial artificial chromosome (BAC) construct and established 2 lines of transgenic rats that coexpress Venus, a yellow fluorescent protein, with the vesicular GABA transporter. The brain GABA content from both transgenic lines was similar to the level found in wild-type rats. In the frontal cortex, Venus was expressed in >95% of GABAergic neurons, most of which also expressed at least one of 6 biochemical markers, including alpha-actitin-2, which preferentially labeled late-spiking neurogliaform cells. Taking advantage of the fact that Venus expression allows for targeted recording from all classes of nonpyramidal cells, irrespective of their somatic morphologies, we demonstrated that fast-spiking neurons, which were heterogeneous in somatic size as well as vertical dendritic projection, had relatively uniform horizontal dimensions, suggesting a cell type-specific columnar input territory. Our data demonstrate the benefits of VGAT-Venus rats for investigating GABAergic circuits, as well as the feasibility of using BAC technology in rats to label subsets of specific, genetically defined neurons.

ARCTOSA STIGMOSA AND A. SUBAMYLACEA ARE TWO DIFFERENT SPECIES (ARANEAE, LYCOSIDAE)

Abstract The Asian wolf spider Arctosa subamylacea (Bosenberg & Strand 1906), originally described from Japan, is currently treated as a junior synonym of the European Arctosa stigmosa (Thorell 1875). However, both species differ noticeably in genital and somatic morphology. Here, we remove A. subamylacea from its synonymy with A. stigmosa and redescribe both species from material recently collected in Asia and Europe. Both species differ in their habitat preferences, as A. stigmosa typically inhabits gravel and sandy habitats in alluvial river floodplains, whereas A. subamylacea lives in low vegetation near hills and in agricultural areas, sometimes near ponds and lakesides.

A distinct group of non-cholinergic neurons along the mid-line of the septum and within the rat medial septal nucleus

The septum is a critical and integral component of the limbic brain that serves as a link between diverse brain structures while being necessary for human cognition and emotionality. A major anatomical component of the septum is designated as the medial septum/diagonal band of Broca complex (MS/DB). A primary focus of much research has been to investigate cholinergic neurons within the MS/DB, as these are the rodent brain's main source of acetylcholine to the cortex and hippocampus. On the other hand, we have chosen to investigate a specific group of neurons that lie on the midline of the MS/DB in an area distinguished anatomically as the medial septal nucleus (MSN). Based on somatic morphology and electrophysiological characteristics we conclude that these neurons, characterized into three different types, are non-cholinergic.

Geographic variation of chromosomes and somatic morphology in the Japanese polymorphic species Leiobunum hiraiwai (Arachnida: Opiliones: Sclerosomatidae)

The hiraiwai-subgroup of the Leiobunum curvipalpe-species group (Opiliones: Sclerosomatidae: Leiobuninae) is revised on the basis of somatic morphology, genitalia and karyotypes. This subgroup is distributed mainly in the mountainous areas of the Japanese Beech (Fagus crenata) forest zone (usually above 700 m in altitude in the southwestern part of Japan) in the western part of the Japanese Islands and corresponds to a single polytypic species, Leiobunum hiraiwai (Sato & Suzuki, 1939) with eight geographic races. Leiobunum tamanum Suzuki, 1957 and L. tsushimense Suzuki, 1976 are here synonymized with L. hiraiwai. All the races, except for the Tsushima race, were chromosomally analyzed. The number of chromosomes varies geographically from 2n = 18 to 22 eastwards, irrespective of the variation in somatic morphology or male genitalia. Component chromosomes in these karyotypes are invariably metacentric or submetacentric in structure. Some morphological characters show a geographic pattern of variation that conforms to the stasipatric model of speciation. The possible processes of geographical differentiation of the species and direction of character evolution are inferred on the basis of such geographical patterns. The distribution of some character states suggests that the closest relative of the subgroup is the curvipalpe-subgroup (= Leiobunum curvipalpe Roewer, 1910 and L. tohokuense Suzuki, 1976) that inhabits the northeastern part of Honshu, Japan. The hiraiwai-subgroup (= Leiobunum hiraiwai) shows a mutually exclusive or checkerboard pattern of geographical distribution with regards to the montanum-subgroup (= Leiobunum montanum Suzuki, 1953) in southwestern Japan, suggesting some possible reproductive interference between these two species.

Phylogenetic analysis of the Squilloidea (Crustacea:Stomatopoda)

Squilloidea is the most speciose of the stomatopod superfamilies and comprises more than 40 genera. Until 2001, three families were recognised: two extant (Harpiosquillidae, Squillidae) and one extinct (Ursquillidae). Recent studies, however, suggested that Harpiosquillidae is nested among other squillids and was thus synonymised with Squillidae. Interrelationships of all squilloid genera are studied by cladistic analysis based on somatic morphology. Results are used to assess the familial classification and investigate the ‘shape’ of squilloid evolution. The phylogeny of the squilloids shows general trends in the armature of the raptorial claw, increased dorsal carination, a tendency for bilobation of the lateral processes of the exposed thoracic somites, and a change in telson shape from trianguloid with movable submedian teeth, to quadriform with fixed submedian teeth. Harpiosquilla Holthuis, 1964 is deeply nested among other squillid genera, supporting the recent synonymy of the Squillidae and Harpiosquillidae. Characters of the late Cretaceous Ursquillidae show that it is highly derived and is therefore synonymised with Squillidae. Although the antiquity of Ursquilla Hof, 1998 does not show it to be a basal or stem-lineage squilloid, it does show that the squilloids had already undergone significant diversification by the end of the Cretaceous. Species of most squilloid genera are regionally restricted, either to the Indo-west Pacific or Atlanto-east Pacific. Only Alima Leach, 1818, Cloridopsis Manning 1968b, and Pontiosquilla Manning, 1995 are represented in both regions.

The phylogenetic placement and circumscription of the genus Synotaxus (Araneae : Synotaxidae), a new species from Guyana, and notes on theridioid phylogeny

The genus Synotaxus Simon, 1895 is reviewed. Modern systematic work has challenged the classical placement of Synotaxus as an argyrodine theridiid. Its placement is evaluated in a phylogenetic analysis containing a wide selection of theridiids, including all major argyrodine genera. For the analysis, two published matrices are fused to produce a dataset containing 83 orbicularian taxa and 302 morphological characters. Although the two matrices share only 10 taxa and 33 characters, a single most parsimonious tree is obtained. The results are congruent with results from each independent matrix, and unambiguously corroborate the placement of Synotaxus outside Theridiidae. Some superficial similarities, such as the elongate abdomen extending far beyond the spinnerets, are clearly convergent in the two taxa. Synotaxus, furthermore, lacks the suite of synapomorphies defining Theridiidae. Thus, its transfer out of Theridiidae is corroborated, and a sister relationship with Chileotaxusi Platnick, 1990 is proposed, based on similarities in web and somatic morphology. A synapomorphy-based circumscription of the genus is given. Synotaxus waiwai, sp. nov. is described, Synotaxus monoceros (Caporiacco, 1947), previously only known from males, is redescribed and synonymised with S. pupularum, Exline & Levi, 1965, syn. nov., previously only known from females. A description of the webs of both species is given, as well as that of Chileotaxus sans Platnick, 1990. Many further Synotaxus species remain to be described.

CHROMOSOME STUDIES IN TURKISH SPECIES OF NONEA (BORAGINACEAE): THE ROLE OF POLYPLOIDY AND DESCENDING DYSPLOIDY IN THE EVOLUTION OF THE GENUS

Seven Turkish species of Nonea Medik. (Boraginaceae-Boragineae) were studied karyologically using material collected in the field from wild populations. Somatic chromosome number and karyotype morphology were determined for each species using orcein staining. Nonea pulmonarioides is diploid with 2n=20, though some cells showed 2n=19. Nonea anchusoides turned out to be tetraploid with 2n=4x=40, while N. macrosperma was characterized by a hexaploid complement of 2n=6x=60. These data indicate polyploidy based on x=10 as a major mechanism of speciation in the perennial members of the genus. Among the annuals, N. echioides and N. versicolor showed 2n=16, while N. obtusifolia and N. lutea were characterized by 2n=20 and 2n=14, respectively. The results reveal that x=10 is more frequent in Nonea than previously realized, and that it may be the ancestral haploid number of diploid endemics of (sub)alpine habitats in the Pontic-Caucasian mountain system. The hypothesis is here proposed that the base numbers x=9, x=8 and x=7, progressively prevalent in the annual species from lower altitudes, may have originated through descending dysploidy associated with the tendency to shorten the life cycle as an adaptation to arid habitats.

The influence of body weight on food and shape attitudes in severely obese patients.

Cognitive restraint, binge eating, night eating, body image disparagement and shape overconcern describe the food and weight related attitudes of obese patients. At long term follow-up after biliopancreatic diversion, body weight is steadily at normal or nearly normal levels regardless of food intake: any preoccupation for food, weight and diet are thereafter completely abandoned. The normalization of body shape corresponds to a sharp improvement in eating behavior, body image and psychological conditions. These results suggest that the dissatisfaction of one's somatic morphology and the consequent dieting account for most of the aberrant eating patterns in obese patients.

Ultrastructural Characterizations of Olfactory Pathway Neurons in Layer II of the Entorhinal Cortex in Monkey

The somatic size, shape, dendritic and axonal morphology, and synaptology of representative neurons in layer II of the primate entorhinal cortex (EC) were analyzed. Layer II ?islands? contained large spinous multipolar cells with triangular somata and local circuit axons in addition to multipolar neurons with large, radially arrayed, aspinous, primary processes and thick tapering axons. Small pyramidal neurons with a single, spinous, apical primary segment that bifurcated a short distance from the somata were also found in layer II. Subsequent spinous segments of these neurons with long terminal segments exhibited a paucity of branching in addition to having thick axons tapering into subjacent layers. The importance of providing these additional axonal, dendritic, and synaptic characterizations lies in the contextual role these neurons play in the connectional patterns of the EC with regard to olfaction, olfactory memory, and pathological variations.

Cladistic analysis of the Eudaniela species complex (Crustacea: Decapoda: Pseudothelphusidae)

Freshwater crabs of the genus Eudaniela s.l. (Pseudothelphusidae: Kingsleyini) are found along the Andean and Coastal Cordillera of Venezuela and in the highlands of Isla Margarita, Trinidad and Tobago. Four of the five species in the genus are very similar in both genital and somatic morphology and may constitute a sibling species complex. A cladistic analysis of morphological characters was conducted to test the monophyly of the genus by using multiple outgroups from the tribe Kingsleyini and to resolve the relationships of the sibling species complex. As presently constituted, Eudaniela is a paraphyletic group, with E. pestai positioned as the most basal taxon within all kingsleyinine taxa compared. The internal relationships within Eudaniela s.s. are [E. garmani [E. iturbei [E. ranchograndensis, E. trujillensis]]].

Spermatozoal ultrastructure in three species of hydrothermal vent crab, in the genera Bythograea, Austinograea and Segonzacia (Decapoda, Brachyura, Bythograeidae)

Summary The ultrastructural investigation of the spermatozoal morphology of the hydrothermal vent crabs, Bythograea thermydron, Austinograea alayseae and Segonzacia mesatlantica (family Bythograeidae) reveals a consistent familial sperm type and a close similarity between the three genera and the deep water trapeziid, Calocarcinus africanus. Association of the bythograeids with Calocarcinus is supported (apart from general similarity) by three synapomorphies: modification of the xanthid ring, development of a well developed periopercular rim (weakly shared with some xanthid and potamid members) and, as a particularly striking link, the unique spiral configuration of the contents of the outer acrosome zone. Calocarcinus is distinguished by shortening of the posterior dense zone into a true xanthid ring and, less so, by a flatter operculum. Bythograea and Segonzacia are apomorphic in the independent loss of the ragged outer acrosome profile. Their sister genus Austinograea has no distinct apomorphies (with the possible exception of an apical perforation in the operculum). The similarity between the spermatozoa of Calocarcinus and the investigated bythograeids and the dissimilarity between Calocarcinus and other trapeziids is evidence for possible inclusion of Calocarcinus in the Bythograeidae. This hypothesized relationship of Calocarcinus within the Bythograeidae sensu lato and its deep water distribution suggests origin of hydrothermal bythograeids from Calocarcinus-like deep water xanthoids which may have entered the hydrothermal system in or after the Eocene. Further investigation of somatic morphology is required to test this putative relationship.

Effects Of Dexamethasone In Rat Neonatal Model Of Axotomy-Induced Motoneuronal Cell Death

In this study the effect of dexamethasone on the motoneuronal cell death and the nuclear and somatic morphology changes occurring after peripheral nerve transection in the neonatal rats has been determined. The study was performed on 3 day old Wistar rats. Animals were divided into 3 groups – control, axotomised, and axotomised and dexamethasone-treated. The nerve transection was performed bilaterally. A dose of 0.5 mg/kg/24h dexamethasone, administered i.p., was used. On day 7 after the operation the animals were sacrificed and the motoneurons in segments L4 and L5 in the spinal cord were counted and their morphology was analysed. 25.88% cell loss was found in the axotomised group (p < 0.001 vs. control) versus 43.33% cell loss in the dexamethasone-treated and axotomised animals (p < 0.01 vs. control). Dexamethasone significantly decreased the number of the surviving motoneurons (p < 0.05 vs. axotomised). The axotomised group showed enlargement of the somatic area and the maximal and minimal diameters of the cell while the dexamethasone-treated and axotomised group showed soma shrinkage and decrease in the minimal cell diameter. Our results propose a possible hazard towards the application of dexamethasone in the treatment of new-borns with concomitant nerve injuries.

Phenotypic Variation in Sexual and Somatic Morphology in the Trapdoor Spider Misgolas hubbardi Wishart in Relation to its Genotypic Variation (Mygalomorphae: Idiopidae)

Spiders from 13 widely separated populations of Misgolas hubbardi Wishart are shown to exhibit distinct phenotypic and genotypic differences in the first such study on ground dwelling spiders in Australia. Electrophoretic analysis also supports the conclusion that the syntopic and morphologically constituted M. hubbardi Wishart, M. dereki Wishart and M. robertsi (Main and Mascord) are valid species. While M. hubbardi can be reliably determined from male palpal characters, the shape of the embolic apophysis and the ventum pigmentation pattern are variable and valid diagnostic characters only for particular populations and where the locality is known. the morphological differences in M. hubbardi populations are summarised and its distribution compared to the geology of the region.

Projections from the ventral cochlear nucleus to the inferior colliculus and the contralateral cochlear nucleus in guinea pigs

Multipolar cells in the ventral cochlear nucleus are the source of projections to numerous brainstem auditory nuclei, including the contralateral and ipsilateral inferior colliculi and the contralateral cochlear nucleus. Multiple fluorescent tracers were used to label the multipolar cells that project to each of these targets. Following injections of different tracers into each target, the ventral cochlear nucleus was examined for the presence of cells that contained more than one tracer. Such cells were never observed. In contrast, double-labeled cells were common in the dorsal cochlear nucleus, where cells frequently contained the two tracers that were injected into the ipsilateral and contralateral inferior colliculi. The distribution and somatic morphology of cells in the ventral cochlear nucleus that project to each of the three targets were examined. Each population contained cells with somas that ranged in shape from elongated to rounded, but there were differences in soma size. Projections to the ipsilateral and contralateral inferior colliculi arise predominantly from small to medium-sized cells, the average size being slightly less for cells with projections to the ipsilateral colliculus. Projections to the contralateral cochlear nucleus arise from cells with somas that range in size from small to large, including cells much larger than those that projected to either inferior colliculus. On the basis of these results, we conclude that projections from the ventral cochlear nucleus to the ipsilateral and contralateral inferior colliculi and to the contralateral cochlear nucleus arise in three different populations of multipolar cells.

Spermatophore and Spermatozoal Morphology in the Porcellanidae. II. The Genera Petrolisthes and Polyonyx (Decapoda: Anomura)

ABSTRACT The porcellanid genera Petrolisthes and Polyonyx are shown to have differing spermatozoal morphology reflecting an apparently natural division of the family previously suggested on adult and larval somatic morphology. Species investigated in the genus Petrolisthes have spermatozoa with a globular nucleus and autapomorphic opercular ridge and tubular ring structure within the acrosomal vesicle. Spermatozoa of Polyonyx transversus (Haswell) have a long taillike nucleus penetrated throughout by a central microtubular core. This latter spermatozoal morphology is shared with other members investigated in the Porcellana-group, (Aliaporcellanaand Pisidia). All the Porcellanidae investigated share a suite of spermatozoal characters that unite them (superior acrosomal vesicle; broad, centrally perforate operculum; 4 or more external microtubular arms; perforatorial chamber wall folded into corrugations or septa; dense perforatorial cone; posterior perforatorial ring and divided inner acrosome zone). A unique spermatophore morphology, consisting of a tubular extension of the anterior end of the ampulla, is described for representatives in the genus Petrolisthes.

A karyological study ofAllium rouyiGautier (Liliaceae), a recently rediscovered endemic species from the south of Spain

A population ofAllium rouyi,previously considered an extinct species, has recently been rediscovered. From this sample, the somatic chromosome number and detailed chromosome morphology is presented. Using the karyological data, relationships betweenA. rouyiand allied species are discussed.

Cytological evidence for the hybrid origin ofCoixtaxon (2n= 32)

SUMMARYIn the present study, karyological characteristics of two taxa of Coix and their hybrid were described. In Coix taxon (2n = 32) the somatic chromosome morphology showed 12 conspicuously large chromosomes, which show resemblance in dimensions and karyotype to the 12 somatic chromosomes of C. gigantea (2n = 12). The similarity between the basic karyotypes of C. gigantea (2n = 12) and the 12 large somatic chromosomes of Coix taxon (2n = 32) evidences their close taxonomic affinity. The meiotic analysis of the F1 back-cross hybrids (2n = 22) between Coix taxon (2n = 32) and C. gigantea (2n = 12) showed six large bivalents and five smaller bivalents in the PMCs. The presence of six large bivalents in the PMCs indicates that the large chromosomes derived from both parents are genetically homologous and this may be regarded as the most convincing evidence regarding the cytogenetical affinity between the two taxa. It is suggested that Coix taxon (2n = 32) is of hybrid origin, with C. gigantea (2n = 12) as ...

Cladistics and the comparative morphology of linyphiid spiders and their relatives (Araneae, Araneoidea, Linyphiidae)

This paper provides the first quantitative cladistic analysis of linyphiid morphology. Classical and novel homology hypotheses for a variety of character systems (male and female genitalia, somatic morphology, spinneret silk spigot morphology, etc.) are critically examined and studied within a phylogenetic context. Critical characters have been illustrated. A sample of linyphiid taxa (nine genera in four subfamilies), five species of Pimoa (Pimoidae), and two other araneoid families (Tetragnathidae and Araneidae, represented by Tetragnatha and Zygiella, respectively) were used to study the implications of the phylogeny of Pimoidae for the systematics of linyphiids. The phylogenetic relationships of these 16 exemplar taxa, as coded for the 47 characters studied, were analysed using numerical cladistic methods. In the preferred cladogram Pimoidae and Linyphiidae are sister groups, Stemonyphantinae are sister group to the remaining linyphiids, and Mynogleninae are sister group to the clade composed of Erigoninae plus Linyphiinae. These results agree with the relationships recently proposed by Wunderlich, except by finding erigonines as the sister group to linyphiines rather than to mynoglenines.