Rostral Lobe Research Articles

Geometric morphometric analysis of Idiognathodus species across the Atokan-Desmoinesian boundary in north-central New Mexico, USA

Landmark-based geometric morphometric analysis of three Idiognathodus species that occur in highest Atokan to lower Desmoinesian strata in New Mexico, I. salensae, I. obstipus, and I. amplificus , show that they represent three similar but distinctive P 1 element species. Idiognathodus salensae has the most twisted element and the smallest, most restricted rostral lobe. Idiognathodus amplificus has the least twisted element and has the largest, most expanded rostral lobe. Idiognathous obstipus represents an intermediate taxon between these two end members. The sinistral elements are more clearly distinguishable between the species than the dextral elements. Other oral features of the P 1 element in these species are highly variable and the analyses demonstrate plasticity in carinal length, adcarinal ridge constriction, transverse ridge disarticulation, and the size and arrangement of nodes on the lobes. These variations and the overall shape changes in ontogeny and chirality are interpreted to be intraspecific variability and are not useful for species discrimination in this group of species. The morphological groups were distinguished along canonical variance axes but not differentiated by principal component axes, highlighting the importance of using canonical variant analysis to detect specific variations undetected by principal component analysis.

Topography of Emotions in Cerebellum as Appraised by Functional Imaging.

Emotions induce complex patterns of cerebellar activity likely reflecting specific cerebellar modulation and multidimensional integration of the emotional experience, based on context-specific dynamic recruitment of limbic, cognitive, mnesic, and sensorimotor cortico-cerebellar loops. Meta-analyses have reported constant recruitment of lobules VI-VII during basic emotions. Activation of rostral lobules II-VI and lobule VIII may be preferentially in relation to motor responses, whereas rostral and caudal vermal activation may be linked to autonomic regulation and associative learning in conjunction with amygdala. Cognitive integration of emotion may rely, at least, on activation of limbic salience network (automatic bottom-up detection of salient stimulus), default-mode network (memory- and knowledge-based categorization), and central executive network (response selection and emotion regulation). As lobules VI-VII straddle all these intrinsically networks, it could be hypothesized that this part of the neocerebellum constitutes an integrator/modulator hub of the emotion-related limbic and cognitive system.

Vanmaneniamarmorata, a new species of loach (Teleostei: Gastromyzontidae) from the middle Chang-Jiang Basin in Guizhou Province, south China.

BackgroundThe gastromyzontid genus Vanmanenia was established by Hora in 1932, based on the type species Vanmaneniastenosoma. The genus is a loach group adapted to running waters of streams from southern China, northern Vietnam and Laos. Currently, 19 valid species of the genus have been recognised. The northernmost distribution of the genus is the Yangtze River (= Chang-Jiang in Chinese) Basin and five species (V.maculata, V.intermedia, V.stenosoma, V.pseudostriata and V.gymnetrus) have been reported from the Basin.New informationVanmaneniamarmorata, a new hillstream species of loach, is here described from the middle Chang-Jiang Basin in Guizhou Province, south China. It is distinguished from its congeners by having a combination of the following characters: three triangular-shaped rostral lobules; postdorsal saddles wider than interspaces; a more backwards-placed anus (the vent to anal distance 30.5–36.9% of the pelvic to anal distance); a larger gill opening with its upper extremity reaching the level of the middle of the orbit; anal-fin base length 5.6–6.4% of SL; caudal-peduncle length 11.6–12.9% of SL; prepelvic length 51.1–53.4% of SL. Its validity is also affirmed by its distinct cyt b gene sequence divergence with all sampled congeners and its monophyly recovered in a cyt b gene-based phylogenetic analysis.

Vanmanenia intermedia Fang, 1935, a valid hill-stream species of loach (Teleostei: Gastromyzontidae) from the middle Yangtze River basin, Southwest China.

Vanmanenia intermedia, which has long been synonymized with V. pingchowensis since 1980, is here revalidated using morphological characters and molecular evidences, and redescribed on the basis of topotypic specimens. This species is distinguished from all other congeneric species by the following combination of characters: triangular-shaped rostral lobules without secondary rostral barbels; distal edge of dorsal-fin slightly concave; no longitudinal black stripe on the flank; a longer snout (length 52.6-64.5 % of HL); a more backwards-placed anus (the vent to anal distance 34.7-46.1% of the pelvic to anal distance); a slender caudal peduncle (depth 9.1-11.3 % of SL); a longer anal-fin base (length 7.5-9.5 % of SL); and a smaller gill opening with its upper extremity closer to the level of the lower margin of the orbit. The validity of V. intermedia is also confirmed by its significant cyt b gene sequence divergence with all sampled congeneric species and its monophyly recovered in the cyt b gene-based phylogenetic analysis.

Two unusual new species of Caleremaeus (Acari: Oribatida) from eastern North America, with redescription of C. retractus and reevaluation of the genus

The oribatid mite genus Caleremaeus (Caleremaeidae) is widely distributed in the northern hemisphere but has been represented by only three extant and one fossil species. We redescribe the North American C. retractus (Banks, 1947) based on adults and nymphs; it is distinguishable from the European type species, C. monilipes (Michael, 1882) by its smaller adult size and minor differences in cuticular structure, and by the elongated, tapered form of seta h1 in nymphs. Two new species are proposed: C. nasutus n. sp. from forest soil in Alabama is unique in having adults with a large anterior rostral lobe (juveniles unknown) bearing lamellar setae; the arboreal C. arboricolus n. sp. from eastern USA and Canada is unique among described extant species in having adults with femoral saccules, a transverse ridge bearing lamellar setae and relatively large notogastral setae, and juveniles with a bothridial seta similar to that of the adult. Based on all available data, Caleremaeus is redescribed and considered the sole genus in Caleremaeidae. The higher classification of the family is reviewed, and past placement in Ameroidea is rejected in favor of the monofamilial Caleremaeoidea.

Loaches of Vanmanenia (Cypriniformes: Gastromyzontidae) from Yunnan, China with Description of a New Species.

After comparing specimens of Vanmanenia collected from the Lancang-jiang (the upper Mekong River), Yuan-jiang (the upper Red River), Lixian-jiang (first branch of the Red River), and Jinsha-jiang (the upper Yangtze River) drainages in Yunnan, China, we considered the specimens of Vanmanenia from Shunbi Township, Yangbi County, Yunnan (a branch of the Lancang-jiang drainage basin, the upper Mekong River) a new species, herein named V. microcephala sp. nov. Our investigation also suggested that V. striata should be restored as a valid species. On the basis of the systematic comparison of morphological characteristics of the genus Vanmanenia and based on the combination of the characteristics of the rostral fold, rostral barbels, the bars/marks on the flank, the rows of spots on the paired fins, and the markings on the caudal-fin base, the loaches of Vanmanenia should be divided into three groups: 1) the barred group, characterized by bars on the flank, 2), the cusped rostral fold group, characterized by the rostral fold lobes forming a cusp process, and 3) the barbeled rostral fold group, characterized by the rostral fold lobes specialized as secondary barbels. The barred group differs from congeners in Vanmanenia by the following combination of characters: three rostral lobes with a smooth and arcuate outer edge, a pattern of bars on the flank, and spotless paired fins. This group includes six species: V. crassicauda, V. microcephala sp. nov., V. serrilineata, V. striata, V. tetraloba, and Vanmanenia pseudostriata. The new species, V. microcephala, differs from the other species in the barred group by the following combination of characters: the lateral side of the body with 14-22 vermiculations with widths smaller than the diameter of the eye; the dorsal side of the head covered with a large black blotch; the gill opening smaller and its upper angle aligned with the lower edge of the eye; and the head smaller, head depth 45.2-47.1% head length. The characteristic evolutionary trends, origin, and taxonomic status of the barred group in the genus Vanmanenia are also discussed.

Lobulation pattern of the of the cerebellum of African grasscutter (<i>Thryonomys swinderianus</i>)

Grasscutter is one of the largest species of rodents in Africa whose basic cerebellar folding pattern has not been documented. The aim of the research was to provide reference data on the lobulation morphometric of its cerebellar cortex. A quantitative analysis was conducted on the cerebella of seven African grasscutters. The results showed that the head weight had strong positive correlation with the cerebellar weight (r = 0.8954, P < 0.001). In the rostral lobe, the mean size of declive was significntly larger than Lingula cerebelli (P < 0.01) and culmen (Pars caudalis) (P < 0.001). Also, the culmen Pars rostralis differed signigifcantly with Pas caudalis (P < 0.01). For the Lobus caudalis, the mean folium vermis was significantly higher than those of the tuber vermis and nodulus (Ps < 0.001). The ovula vermis was the broadest lobule in this lobe, was significantly larger than the tuber vermis the pyramis, and nodulus (Ps < 0.001). The mean internal perimeter, including all primary and secondary sublobules (4643.3 ± 341.69 μm) was higher than the external perimeter (1621 ± 42.43 μm) significantly (P < 0.0001). The mean cerebellar foliation index was 2.86 ± 0.18; suggesting a relatively increased in length of cerebellum in form of a folded structure. In conclusion, some of the structural development and behaviours in the grasscutter may likely be correlated with the relative sizes of individual cerebellar lobules.Keywords: Cerebellum, lobes, lobules, morphometric, T. swinderianus

The smallest ‘true chameleon’ from Madagascar: a new, distinctly colored species of the Calumma boettgeri complex (Squamata, Chamaeleonidae)

On a recent expedition to eastern Madagascar, we discovered a distinct new species of the genusCalummathat we describe here using an integrative approach combining morphology, coloration, osteology and molecular genetics.Calummaroalokosp. n.has a dermal rostral appendage and occipital lobes, and belongs to theC.boettgericomplex, within the Madagascar-endemic pheneticC.nasutumspecies group. It is readily distinguished from other species of theC.boettgericomplex by a characteristic two-toned body coloration and small body size with a snout-vent length of 45.6 mm in an adult male. The osteology of the skull, with a prominent maxilla and broad parietal, is similar to the closest related species,C.uetzi. Analysis of uncorrected genetic distances within theC.nasutumgroup using the mitochondrial gene ND2 shows a minimum pairwise distance of 11.98% toC.uetzifrom the Sorata massif and Marojejy National Park >500 km north of the type locality ofC.roalokosp. n.. Given an apparently small range (potentially <300 km2), located entirely outside of any nationally-protected areas, we recommend this new species be classified as Endangered under criterion B1ab(iii) of the IUCN Red List. The discovery of clearly distinct species likeC.roalokosp. n.in an area of Madagascar that is comparatively thoroughly surveyed highlights the critical role of continued field surveys for understanding the true extent of Madagascar’s spectacular biodiversity.

Geometric morphometric analysis and taxonomic revision of the Gzhelian (Late Pennsylvanian) conodont Idiognathodus simulator from North America

A new morphometric approach was developed to study morphological variation within P1 elements commonly referred to as Idiognathodus simulator, which was selected to be the biostratigraphic marker for the base of the global Gzhelian Stage (Carboniferous). This new approach combines landmark-based geometric morphometrics with eigen analyses to analyze shape variation within P1 elements of the I. simulator group, and could be used to analyze shape variation in other morphologically similar conodont groups. Specimens analyzed were obtained from three sections of the early Gzhelian Heebner Shale of the Oread cyclothem in the North American Midcontinent region, the cyclothem from which I. simulator was originally named. This analysis shows that the I. simulator group comprises a set of at least five species with asymmetrical P1 element pairs, relatively short adcarinal ridges, and a variably developed eccentric groove. Species discrimination is based on the presence of caudal and rostral lobes, character of the...

Aletheiana tenella, a new genus and new species of freshwater hymenosomatid crab (Crustacea: Decapoda: Brachyura) from Central Sulawesi, Indonesia.

A new genus and new species of free-living hymenosomatid crab, Aletheiana tenella, is described from Central Sulawesi, Indonesia. The two known Sulawesi hymenosomatid species, Cancrocaeca xenomorpha Ng, 1991, and Sulaplax ensifer Naruse, Ng & Guinot, 2008, are both from cave habitats. Aletheiana gen. nov. is most similar to Neorhynchoplax Sakai, 1938 (from freshwater and intertidal habitats in the Indo-West Pacific), and Sulaplax, but can be distinguished by its front possessing only one subventral rostral lobe, the base of the antenna is positioned between the base of the ocular peduncle and antennular fossa, the posterior margin of the epistome has two low, rounded median lobes, the merus of the third maxilliped is elongated, the ambulatory dactylus has a prominent subdistal spine, the cutting edges of the chela are armed with distinct teeth proximally, and the male abdomen is slender and elongate with the telson linguiform.

Compartmentalization of the chick cerebellar cortex based on the link between the striped expression pattern of aldolase C and the topographic olivocerebellar projection.

The avian cerebellum is organized into multiple longitudinal stripes defined by expression profiles of aldolase C (zebrin II) in Purkinje cells. The relationship between the aldolase C striped pattern and the olivocerebellar projection pattern is crucial in understanding cerebellar functional compartmentalization. We identified all aldolase C stripes across all lobules with the serial section alignment analysis method and then looked at this relationship by anterograde and retrograde labeling of olivocerebellar axons in the chick cerebellum. Aldolase C stripes were generally consistent and continuous from lobule I through VII and to the medial part of lobules VIII-IXb. The dorsal and ventral lamellas (DL, VL) of the inferior olive projected to the stripes in these areas with a simple mediolateral topographic relation. A few aldolase C stripes appeared at the lateral edge of lobules VI-VIII. Several more stripes were added in the lateral parts of lobules IXa-IXb and IXc-X. The medial column (MC) of the inferior olive projected to the stripes in lobules VIII-X, including the added lateral stripes, with a complex topographic relation. Sharp boundaries between aldolase C-positive and -negative stripes often accompanied a gap in the Purkinje cell layer and bordered topographically distinct groups of axons. Although the compartmental organization of the chick cerebellum is comparable to that of the mammalian cerebellum, several significant differences in the organization suggest partly separate evolutionary lineages of the mammalian and avian cerebella. We propose that rostral lobules may be evolved by rostral extension of medial stripes from caudal lobules in the avian cerebellum.

A revised generic arrangement for the eagle ray family Myliobatidae, with definitions for the valid genera.

The generic arrangement of the eagle rays (Family Myliobatidae) is revised and the genus Pteromylaeus Garman, 1913 is placed into the synonymy of Aetomylaeus Garman, 1908. Definitions are provided for the three valid genera, Aetobatus, Aetomylaeus and Myliobatis, and nomenclatural issues are discussed. Aetobatus differs from the latter two genera in having: a deeply notched nasal curtain, both jaws with a single row of chevron-shaped teeth, broadly rounded pectoral-fin free rear tips, pectoral fins separate from rostral lobe and joining head at level of eye. Aetomylaeus differs from the other two genera in having: pectoral fins separate from rostral lobe and joining head below level of eye, and stinging spine absent or present (usually not well developed when present). Myliobatis differs from the other two genera in having the pectoral fins joined to the rostral lobe by a subocular ridge. A list of valid species is provided, including a list of junior synonyms. Myliobatis australis Macleay, 1881 from southern Australia is placed into the synonymy of the previously considered endemic New Zealand species, M.tenuicaudatus Hector, 1877.

Vanmanenia maculata, a new species of hillstream loach from the Chang-Jiang Basin, South China (Teleostei: Gastromyzontidae).

Vanmanenia maculata, new species, is described from the middle and lower Chang-Jiang basin in Hubei, Hunan, and Jiangxi provinces, South China. This new species, along with V. caldwelli, V. stenosoma, and V. striata, is distinguished from all other Chinese species of the genus by lacking secondary rostral barbels. It is distinct from V. caldwelli and V. striata in anus placement, rostral lobule shape, and body coloration, and from V. stenosoma in having a larger scaleless area on the ventral surface of the body and a shallower caudal-peduncle. Vanmanenia polylepis should be removed from the synonymy of V. pingchowensis and regarded as valid.

Characterization of pituitary growth hormone and its receptor in the green iguana (Iguana iguana)

Pituitary growth hormone (GH) has been studied in most vertebrate groups; however, only a few studies have been carried out in reptiles. Little is known about pituitary hormones in the order Squamata, to which the green iguana (gi) belongs. In this work, we characterized the hypophysis of Iguana iguana morphologically. The somatotrophs (round cells of 7.6-10 μm containing 250- to 300-nm secretory granules where the giGH is stored) were found, by immunohistochemistry and in situ hybridization, exclusively in the caudal lobe of the pars distalis, whereas the lactotrophs were distributed only in the rostral lobe. A pituitary giGH-like protein was obtained by immuno-affinity chromatography employing a heterologous antibody against chicken GH. giGH showed molecular heterogeneity (22, 44, and 88 kDa by SDS-PAGE/Western blot under non-reducing conditions and at least four charge variants (pIs 6.2, 6.5, 6.9, 7.4) by isoelectric focusing. The pituitary giGH cDNA (1016 bp), amplified by PCR and RACE, encodes a pre-hormone of 218 aa, of which 190 aa correspond to the mature protein and 28 aa to the signal peptide. The giGH receptor cDNA was also partially sequenced. Phylogenetic analyses of the amino acid sequences of giGH and giGHR homologs in vertebrates suggest a parallel evolution and functional relationship between the GH and its receptor.

Inferior vermian hypoplasia – preconception, misconception

Inferior vermian hypoplasia – preconception, misconception

A New Species of the Genus Garra Hamilton, 1822 from the Chindwin Basin of Manipur, India (Teleostei: Cyprinidae: Labeoninae)

Garra namyaensis sp. nov., a new cyprinid fish, is described from the Chindwin River basin in Manipur, India. It is distinguished from its congeners in having a unique combination of the following characters: smoothly rounded snout tip with a prominent rostral lobe, chest and abdominal region with scales, dorsal fin with a black band near the posterior margin, and caudal fin with a distinct W-shaped black band.

Semaphorin 4C and 4G are ligands of Plexin-B2 required in cerebellar development

Semaphorins and Plexins are cognate ligand-receptor families that regulate important steps during nervous system development. The Plexin-B2 receptor is critically involved in neural tube closure and cerebellar granule cell development, however, its specific ligands have only been suggested by in vitro studies. Here, we show by in vivo and in vitro analyses that the two Semaphorin-4 family members Sema4C and Sema4G are likely to be in vivo ligands of Plexin-B2. The Sema4C and Sema4G genes are expressed in the developing cerebellar cortex, and Sema4C and Sema4G proteins specifically bind to Plexin-B2 expressing cerebellar granule cells. To further elucidate their in vivo function, we have generated and analyzed Sema4C and Sema4G knockout mouse mutants. Like Plexin-B2-/- mutants, Sema4C-/- mutants reveal exencephaly and subsequent neonatal lethality with partial penetrance. Sema4C-/- mutants that bypass exencephaly are viable and fertile, but display distinctive defects of the cerebellar granule cell layer, including gaps in rostral lobules, fusions of caudal lobules, and ectopic granule cells in the molecular layer. In addition to neuronal defects, we observed in Sema4C-/- mutants also ventral skin pigmentation defects that are similar to those found in Plexin-B2-/- mutants. The Sema4G gene deletion causes no overt phenotype by itself, but combined deletion of Sema4C and Sema4G revealed an enhanced cerebellar phenotype. However, Sema4C/Sema4G double mutants showed overall less severe cerebellar phenotypes than Plexin-B2-/- mutants, indicating that further ligands of Plexin-B2 exist. In explant cultures of the developing cerebellar cortex, Sema4C promoted migration of cerebellar granule cell precursors in a Plexin-B2-dependent manner, supporting the model that a reduced migration rate of granule cell precursors is the basis for the cerebellar defects of Sema4C-/- and Sema4C/Sema4G mutants.

Garra arupi, a new cyprinid fish species (Cypriniformes: Cyprinidae) from upper Brahmaputra basin in Arunachal Pradesh, India

Garra arupi, a new cyprinid fish species is differentiated from its congeners along the base of the Himalaya in Brahmaputra basin by a combination of characters: two pairs of barbels, anterior position of vent (vent to anal distance 52.6-60.0% pelvic to anal distance), a band of 6-9 prominent horny tubercles on the tip of the snout, a submarginal black band on the dorsal fin, and 16 circumpeduncular scales. It is similar to G. kempi in having an anterior position of the vent, and similar to G. lissorynchus in having a distinct submarginal band on the dorsal fin. Garra arupi differs from G. kempi in having 35-36 (vs. 40-42) lateral line scales, 11-12 (vs. 13-14) predorsal scales, 16 (vs. 12) circumpeduncular scales, the presence of a distinct submarginal band on the dorsal fin (vs. absence), the presence of a transverse band of tubercles on the snout tip (vs. absence), and the presence of 7-8 thin stripes on the caudal peduncle (vs. absence). Garra arupi differs from G. lissorynchus in having 11-12 (vs. 14-15) predorsal scales, 7 (vs. 6) branched dorsal fin rays, 5 (vs. 4) branched anal fin rays, the absence of a W-shaped color band on the caudal fin (vs. presence), the absence of a rostral lobe on the snout (vs. presence), the presence of a transverse band of tubercles on the snout tip (vs. absence), and a vent to anal distance 52.6-60.0 (vs. 37.3-40.2 %) pelvic to anal distance.

Morphologic features of the cerebellum of the Atlantic stingray, and their possible evolutionary significance

The morphology of the cerebellar corpus in cartilaginous fishes varies from a smooth, relatively simple structure to a complex, multilobed structure. Atlantic stingrays possess a trilobed corpus that includes an anterior lobe, divided into rostral and caudal lobules, and a posterior lobe. The corpus in this stingray is assymetrical. This asymmetry was examined in the stingray population of Galveston Bay. In 49% of the animals the axis of the caudal lobule was right of the midline, in 27% it was across the midline, and in 24% it was to the left. This variation is not related to size, sex, or an asymmetry in the cranial volume, but might reflect a variation in the cerebellar developmental program. To gain insight into the factors that have driven cerebellar hypertrophy in cartilaginous fishes, the neural connections of the lobules of the cerebellum of the Atlantic stingray were examined using biotinylated dextrans. It was found that, for the most part, the stingray cerebellum receives inputs from the same diencephalic and brainstem nuclei as in cartilaginous fishes with a bilobed cerebellum. However, in stingrays there is greater segregation of inputs. The anterior lobe rostral lobule receives inputs from the accessory optic nuclei, the caudal lobule receives inputs from trigeminal and octavolateral nuclei, and the posterior lobe receives inputs from the spinal cord. The rostral lobule and posterior lobe also receive input from midbrain nuclei that do not appear to be present in cartilaginous fishes with a morphologically simple corpus. Therefore, it is proposed that the complex hypertrophy of the corpus in stingrays might result from a combination of functional specialization of the lobes, and the acquisition of new inputs.

Ethmoidal encephalocoele associated with seizures in a puppy

A six-month-old puppy was presented for investigation of a seizure disorder. Neurological examination indicated persistent cerebral dysfunction in the absence of any identifiable metabolic disorder and magnetic resonance imaging revealed extension of the rostral lobes of the cerebrum into the nasal cavity. Despite symptomatic treatment, the puppy continued to exhibit seizures and appeared distressed and so was euthanased. Postmortem examination confirmed the abnormal anatomy of the rostral part of the brain and absence of a cribriform plate. There was extensive grey and white matter degeneration plus intraparenchymal haemorrhage in the abnormal brain tissue. The findings are consistent with a diagnosis of ethmoldal encephalocoele--a condition that has not previously been reported in the dog.