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1.
Abstract: Palaeophis maghrebianus belongs to the Palaeophiinae (Palaeophiidae). This snake subfamily is relatively poorly known, and it is mainly represented by disarticulated vertebrae and ribs and by a few vertebral segments. Its intracolumnar variability remains also poorly understood. The discovery of new isolated vertebrae and vertebral segments of Palaeophis maghrebianus in the Ypresian (Lower Eocene) Phosphates of Morocco enables us to provide a more detailed diagnosis of this species and to describe its intracolumnar variability. Moreover, the new material reveals that this species could reach gigantic size being, with Palaeophis colossaeus, one of the two longer palaeophiids. The microanatomical and histological analysis of some vertebrae illustrating diverse positions along the vertebral column reveals the presence of osteosclerosis, especially in the anterior and mid‐precloacal regions. The occurrence of this osseous specialization implies a role in buoyancy and body trim control in this taxon, which is considered a shallow marine dweller based on its anatomical features and geological data. Palaeophis maghrebianus also displays a dense vascular network suggesting a growth speed, and thus a metabolic rate, much higher than in the biggest extant snakes.  相似文献   
2.
ABSTRACT. The systematic relationships and taxonomic positions of the traditional heterotrich genera Condylostentor, Climacostomum, Fabrea , Folliculina, Peritromus , and Condylostoma , as well as the licnophorid genus Licnophora , were re-examined using new data from sequences of the gene coding for small subunit ribosomal RNA. Trees constructed using distance-matrix, Bayesian inference, and maximum-parsimony methods all showed the following relationships: (1) the "traditional" heterotrichs consist of several paraphyletic groups, including the current classes Heterotrichea, Armophorea and part of the Spirotrichea; (2) the class Heterotrichea was confirmed as a monophyletic assemblage based on our analyses of 31 taxa, and the genus Peritromus was demonstrated to be a peripheral group; (3) the genus Licnophora occupied an isolated branch on one side of the deepest divergence in the subphylum Intramacronucleata and was closely affiliated with spirotrichs, armophoreans, and clevelandellids; (4) Condylostentor , a recently defined genus with several truly unique morphological features, is more closely related to Condylostoma than to Stentor ; (5) Folliculina, Eufolliculina , and Maristentor always clustered together with high bootstrap support; and (6) Climacostomum occupied a paraphyletic position distant from Fabrea , showing a close relationship with Condylostomatidae and Chattonidiidae despite of modest support.  相似文献   
3.
ABSTRACT. The morphology and infraciliature of two new marine oligotrich ciliates, Novistrombidium sinicum n. sp. and Novistrombidium orientale n. sp., isolated from a mangrove wetland near Guangzhou, southern China, were studied from live and protargol-stained specimens. Novistrombidium sinicum is different from its congeners by the combination of the following characters: three posteriorly directed thigmotactic membranelles, one ellipsoidal macronucleus, the extrusomes equidistantly arranged, and the ventral kinety commencing below the right end of the girdle kinety. The small-sized N. orientale can be separated from its congeners by two posteriorly directed thigmotactic membranelles, one ellipsoidal macronucleus, the extrusomes equidistantly arranged, and the ventral kinety commencing below the right end of the girdle kinety.  相似文献   
4.
The spatial ecology of wintering Eurasian Woodcocks Scolopax rusticola was investigated to determine whether hunting-free forest reserves offer adequate protection to all individuals. The analysis of movements performed by 65 radiotagged Woodcocks during three consecutive winters in Brittany revealed the existence of three types of individual strategies. During daylight hours, 34% of birds remained in a unique core area (of 1.1 ha) during January and February while 18% used several core areas successively (never came back to a previously used core) and 48% alternated between several core areas (exploratory movements around several core areas visited several times). Alternating diurnal strategies seemed to result from a lower abundance of food (earthworms), whereas this was not the case in the unique core-use strategy. The successive core-use strategy was considered as a subset of the 'unique' strategy, for which birds were forced to change sites because of a lower abundance of food after depletion. During the night, 62% of birds showed alternative core-use whereas 33% lived in a unique core and the 'successive' strategy was almost absent. As food abundance was similar in the night cores used by birds under each strategy, we discuss the reasons for the nocturnal strategies in relation to individual differences in territoriality or the ability to detect predators. Both diurnal and nocturnal strategies led most of the birds to leave the reserve, and the important use of bocage and hedges by day (by 39% of birds) and meadows at night (83% of birds used meadows on more than 70% of nights), around the protected forest, call for their inclusion in management plans around reserves.  相似文献   
5.
The divergence in reproductive features and hybrid fertility patterns between two chromosomal races (2 n  = 40, 40St, and 2 n  = 22, 22Rb) of the house mouse in Tunisia were re-assessed on a larger sample of wild and laboratory-bred individuals than studied hitherto. Results showed that litter sizes were significantly smaller in 40St than in 22Rb mice, contrary to previous analyses. This suggests that variation in litter size between the two chromosomal races is more likely related to selective and/or environmental factors acting locally than to interracial reproductive trait divergence. However, the significantly reduced litter size of F1 hybrids compared with parental individuals was confirmed, and further highlighted a sex difference in hybrid infertility, as F1 females produced fewer litters and of smaller size than males. Histological analyses of F1 and backcrosses showed a breakdown of spermatogenesis in males and a significantly reduced primordial follicle pool in females. The degree of gametogenic dysfunction was not related to the level of chromosomal heterozygosity per se , but a significant effect of two Rb fusions on follicle number was observed in hybrid females. These results suggest that genetic incompatibilities contribute to primary gametogenic dysfunction in hybrids between the chromosomal races in Tunisia.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 84 , 407–416.  相似文献   
6.
ABSTRACT. A new marine cyrtophorian ciliate Trichopodiella faurei n. sp., which belongs to the order Dysteriida, family Hartmannulidae, was investigated at the morphological and molecular levels. A combination of morphological features of the organism including the oval body shape, 2–3 contractile vacuoles, 22–28 nematodesmal rods in the cytopharyngeal basket, and 31–39 somatic kineties, distinguishes it from all other known congeners. In reconstructed small subunit (SSU) rRNA phylogenies, T. faurei groups with Isochona, a representative genus of the subclass Chonotrichia. The similarity of the infraciliature between hartmannulids and several chonotrichian examples also suggests that these taxa should be closely related. A new S943 intron belonging to group IC1 was identified in the SSU rRNA gene of this species. This intron is phylogenetically related to the S891 introns previously found in the suctorians Acineta sp. and Tokophrya lemnarum, and their internal guide sequences share four nucleotides, indicating that these introns were vertically inherited from a common phyllopharyngean ancestor and that reverse splicing might have been involved in the transposition.  相似文献   
7.
ABSTRACT. The urosylid genus Pseudoamphisiella was established by Song (1996) with hitherto only two known congeners. In the present work, the morphology and infraciliature of a new member, Pseudoamphisiella quadrinucleata n. sp., a form with conspicuous alveolar layer and four macronuclear nodules isolated from the coastal waters both near Hong Kong and near Guangzhou, South China were investigated using living observation and protargol silver impregnation methods. Pseudoamphisiella quadrinucleata differs from other two known forms mainly by the number of macronuclear nodules: constantly four vs. two in Pseudoamphisiella alveolata and 24–57 in Pseudoamphisiella lacazei. To support this, the sequence of the small subunit rDNA of P. quadrinucleata n. sp. showed 14 and 74 nucleotides in comparison with that of the two known congeners, respectively, which hence firmly supports the validity of the new species.  相似文献   
8.
The morphologically unique ciliate Psammomitra has long been considered as a systematically uncertain stichotrich. This is mainly because of its highly specialized morphology and a lack of either detailed information concerning its ontogenesis, or molecular data. Based on the small subunit rRNA (SSrRNA) gene and alpha‐tubulin gene sequences, we re‐evaluated the phylogenetic position of Psammomitra retractilis using multiple algorithms. Phylogenetic trees inferred from the SSrRNA gene sequences representing a total of 53 spirotrichs demonstrated the closest relationship of Psammomitra was with Holosticha‐like taxa, with strong support, which clearly suggested that Psammomitra should be placed into the order Urostylida although it branched at a rather deep level, and is likely to be closely related to Holostichidae. With consideration to molecular evidence and morphological characters, Psammomitra should be a clearly outlined taxon at about the rank of family, i.e. Psammomitridae stat. nov. , within the order Urostylida. The improved diagnosis for this family is as follows: Urostylida possessing extremely contractile, elongated body which consists of three parts: head, trunk, and slender tail; midventral complex composed of midventral pairs only and restricted to about anterior 1/3 of ventral surface; frontal, frontoterminal, and transverse cirri present; one left and one right marginal rows which commence near proximal end of adoral zone and extend to near rear body end.  相似文献   
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10.
Middle Eastern Lives in America . Amir Marvasti and Karyn D. McKinney. Lanham, MD: Rowman and Littlefield. 171 pp.  相似文献   
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