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1.
The small tetrapod Candelaria barbouri, from the Middle Triassic of southern Brazil, is the first example of an owenettid procolophonoid outside Africa and Madagascar. Candelaria barbouri was originally described as a primitive procolophonid; however, a re-examination of the holotype, as well as new material, reveals that C. barbouri is in fact the youngest member of the Owenettidae, extending the chronological range of the group by more than 10 million years. The recognition of C. barbouri as an owenettid points to a broader diversity and distribution for owenettids than hitherto thought. In addition, C. barbouri is the first member of the Owenettidae to exhibit temporal fenestrae, a discovery that draws attention to the significance of this feature in 'anapsid' reptiles.  相似文献   

2.
To persist, unisexual and asexual eukaryotes must have reproductive modes that circumvent normal bisexual reproduction. Parthenogenesis, gynogenesis, and hybridogenesis are the modes that have generally been ascribed to various unisexuals. Unisexual Ambystoma are abundant around the Great Lakes region of North America, and have variously been described as having all 3 reproductive modes. Diploid and polyploid unisexuals have nuclear genomes that combine the haploid genomes of 2 to 4 distinct sexual species, but the mtDNA is unlike any of those 4 species and is similar to another species, Ambystoma barbouri. To obtain better resolution of the reproductive mode used by unisexual Ambystoma and to explore the relationship of A. barbouri to the unisexuals, we sequenced the mitochondrial control and highly variable intergenic spacer region of 48 ambystomatids, which included 28 unisexuals, representatives of the 4 sexual species and A. barbouri. The unisexuals have similar sequences over most of their range, and form a close sister group to A. barbouri, with an estimated time of divergence of 2.4-3.9 million years ago. Individuals from the Lake Erie Islands (Kelleys, Pelee, North Bass) have a haplotype that demonstrates an isolation event. We examined highly variable microsatellite loci, and found that the genetic makeup of the unisexuals is highly variable and that unisexual individuals share microsatellite alleles with sexual individuals within populations. Although many progeny from the same female had the same genotype for 5 microsatellite DNA loci, there was no indication that any particular genome is consistently inherited in a clonal fashion in a population. The reproductive mode used by unisexual Ambystoma appears to be unique; we suggest kleptogenesis as a new unisexual reproductive mode that is used by these salamanders.  相似文献   

3.
Juárez P  Sanz L  Calvete JJ 《Proteomics》2004,4(2):327-338
The protein composition of the crude venom of Sistrurus barbouri was analyzed by two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis. Proteins were separated by reversed phase high-performance liquid chromatography and characterized by N-terminal sequence analysis. The molecular mass and number of cysteine residues of the purified proteins were determined by matrix-associated laser desorption/ionization-time of flight mass spectrometry. Selected protein bands were subjected to in-gel tryptic digestion and peptide mass fingerprinting. Analysis of the tandem mass spectrometry spectra of selected doubly-charged peptide ions was done by collision-induced dissociation in a quadrupole-linear ion trap instrument. Our results show that the venom proteome of the pigmy rattlesnake S. barbouri is composed of proteins belonging to a few protein families, which can be structurally characterized by their disulfide bond contents.  相似文献   

4.
Distinct genetic markers should show similar patterns of differentiation between species reflecting their common evolutionary histories, yet there are increasing examples of differences in the biogeographic distribution of species‐specific nuclear (nuDNA) and mitochondrial DNA (mtDNA) variants within and between species. Identifying the evolutionary processes that underlie these anomalous patterns of genetic differentiation is an important goal. Here, we analyse the putative mitonuclear discordance observed between sister species of mole salamanders (Ambystoma barbouri and A. texanum) in which A. barbouri‐specific mtDNA is found in animals located within the range of A. texanum. We test three hypotheses for this discordance (undetected range expansion, mtDNA introgression, and hybridization) using nuDNA and mtDNA data analysed with methods that varied in the parameters estimated and the timescales measured. Results from a Bayesian clustering technique (structure ), bidirectional estimates of gene flow (migrate ‐n and IMa2) and phylogeny‐based methods (*beast , buck y) all support the conclusion that the discordance is due to geographically restricted mtDNA introgression from A. barbouri into A. texanum. Limited data on species‐specific tooth morphology match this conclusion. Significant differences in environmental conditions exist between sites where A. texanum with and without A. barbouri‐like mtDNA occur, suggesting a possible role for selection in the process of introgression. Overall, our study provides a general example of the value of using complimentary analyses to make inferences of the directionality, timescale, and source of mtDNA introgression in animals.  相似文献   

5.
Four distinct phylogeographical patterns across Southeast Asia were observed for four species of seahorse (genus Hippocampus) with differing ecologies. For all species, genetic differentiation (based on cytochrome b sequence comparisons) was significantly associated with sample site (Phi(ST) = 0.190-0.810, P < 0.0001) and with geographical distance (Mantel's r = 0.37-0.59, P < 0.019). Geographic locations of genetic breaks were inconsistent across species in 7/10 comparisons, although some similarities across species were also observed. The two shallow-water species (Hippocampus barbouri and Hippocampus kuda) have colonized the Sunda Shelf to a lesser degree than the two deeper-water species (Hippocampus spinosissimus and Hippocampus trimaculatus). In all species the presence of geographically restricted haplotypes in the Philippines could indicate past population fragmentation and/or long-distance colonization. A nested clade analysis (NCA) revealed that long-distance colonization and/or fragmentation were likely the dominant forces that structure populations of the two shallow-water species, whereas range expansion and restricted dispersal with isolation by distance were proportionally more important in the history of the two deeper-water species. H. trimaculatus has the most widespread haplotypes [average clade distance (D(c)) of nonsingleton haplotypes = 1169 km], indicating potentially high dispersal capabilities, whereas H. barbouri has the least widespread haplotypes (average D(c) = 67 km) indicating potentially lower dispersal capabilities. Pleistocene separation of marine basins and postglacial flooding of the Sunda Shelf are extrinsic factors likely to have contributed to the phylogeographical structure observed, whereas differences among the species appear to reflect their individual ecologies.  相似文献   

6.
This study describes Characidium nambiquara, a new species from the upper rio Guaporé, rio Madeira basin, Brazil. The new species differs from most congeners by the presence of isthmus and area between the contralateral pectoral-fin bases completely naked. From congeners with some degree of scaleless ventral surface of the body C. nambiquara differs by having 10 circumpeduncular scales. The new species is also distinguished from congeners by the spotted colour pattern on body of the large-sized specimens and by having black dashes on all fins and conspicuous midlateral longitudinal dark stripe or conspicuous vertical bars absent. Characidium nambiquara further differs from most congeners by the presence of 34–36 pored scales on the lateral line, 3 horizontal scale rows above the lateral line and 3 horizontal scale rows from the lateral line to the midventral scale series. Remarks on intraspecific colour variation within the genus, not related to sexual dimorphism, are also provided.  相似文献   

7.
In the present work, firstly, ant emergence was observed: it is a long, stereotyped, precarious event which may require the help of congeners. Then, our experiments on Myrmica sabuleti Meinert 1861 callow ants emerging apart from or inside their colony showed the following points. 1. Newly emerged workers, even if having never olfactorily perceived nestmates, are attracted by congeners’ odor. They can distinguish such an odor from that of another species of Myrmica as well as somewhat from that of alien workers of the same species. So, they might have acquired, at least partly, the knowledge of their congeners’ odor during their larval life. 2. Callow ants having visually perceived congeners at their emergence move towards a presented congener’s washed corpse. Callow ants having emerged without seeing any congeners do not move towards such a corpse. Callow ants having emerged beside a piece of thyme moved towards a non-odorous (solvent-washed) piece of thyme. So, ants may acquire, at least partly, the knowledge of the visual aspect of their species just at their emergence, probably by imprinting. 3. Very young workers confronted with their congeners’ odor on one hand and their congeners’ visual aspect on the other hand, somewhat prefer the odor, even if these young ants belong to a species which exclusively uses its vision for navigating. So, for very young ants, whatever the species, odors are more important and better known than visual characters.  相似文献   

8.
Myleus pachyodus, a new serrasalmid species, is described from the Rio Teles Pires and Rio Jamanxim, both tributaries of the Rio Tapajós in Mato Grosso and Pará states, Brazil. The new species differs from all congeners by having a remarkable ontogenetic thickening of the teeth shifting from slender incisiform in juveniles to thick bulky teeth at standard length ≥ 100 mm, whereas congeners present slender, antero‐posteriorly flat teeth throughout all life stages. The new species further differs from congeners by having 18–20 branched dorsal‐fin rays, by the lack of a diastema between contralateral outer series of premaxillary teeth and by the presence of 16–25 prepelvic spines, with the anteriormost spine never reaching the vertical through the pectoral‐fin origin.  相似文献   

9.
Johnsson  R. 《Hydrobiologia》2001,(1):431-440
Two new artotrogids are recorded from Madeira Island. A new species of Cryptopontius, associated with algae, differs from its congeners in the number of antennular segments, setation of the antennal exopod, setation and length of the maxillule lobes, and setation of both rami of the first and fourth legs. The second new artotrogid belongs to Dyspontius.It was associated with Gerardia savagliae Lacaze-Duthiers, 1864 (Cnidaria: Zoanthidea) and differs from its congeners in cephalothorax shape, siphon length and setation of the maxillule lobes.  相似文献   

10.
In total, 17 specimens of Conger orbignianus Valenciennes, 1847 from waters off Mar del Plata, Argentina (38 degrees 08'S, 57 degrees 32'W) were examined for parasitic nematodes. A new nematode species, Cucullanus pedroi n. sp., is described (prevalence 76.5%, x intensity +/- SD = 3.8 +/- 2.7). The new species closely resembles some species parasitizing other anguilliform fishes; however, it can be distinguished from most of its congeners by the distribution pattern of caudal papillae (particularly fourth and eight pairs) and phasmids. Those congeners with similar pattern of papillae differ from the new species by the length of the spicules and gubernaculum and by the position of the excretory pore and deirids.  相似文献   

11.
A new species of Odontostilbe is described from the rio Jaciparaná, rio Madeira basin, Rondônia, Brazil. Odontostilbe pacaasnovos differs from all its congeners, except O. pequira, by the colour pattern. Additionally, it differs from its congeners by the terminal mouth, number of cusps in the teeth of the premaxilla (5–7), number of branched rays in the anal fin (19–22), by the shape of dentary teeth (5–7 cusps with central cusp larger and longer than laterals cusps) and by the number of lamellae of the olfactory rosette (17–18 in male and 14 in female). Morphological and molecular comparisons corroborate the distinctiveness between O. pacaasnovos and its congeners, justifying its recognition as a new species.  相似文献   

12.
13.
A new species of Hemigrammus is described from the Amazon Basin near Leticia, Departamento Amazonas, Colombia. In common with some congeners and some Hyphessobrycon spp., the new species colour pattern lacks a humeral blotch but has a caudal-peduncle blotch. It can be distinguished from congeners with a similar colour pattern by having: a relatively deep body (30.2%–39.0% LS), 20–24 branched anal-fin rays, 6–8 perforated scales of the lateral line, anal-fin base without a conspicuous black stripe, 3–5 maxillary teeth, maxillary teeth with 1–3 cusps, a thin longitudinal midlateral line and a well-defined oval shaped caudal blotch, extending from caudal peduncle into the lower caudal-fin rays. Comparisons with congeners and with Hyphessobrycon species sharing the same general colour pattern are presented.  相似文献   

14.
Aulonemia yanachagensis is described from cloud forests at 2600–3000 m elevation in the Parque Nacional Yanachaga-Chemillén Prov. Oxapampa, Dept. Pasco, Peru. It differs from all other congeners in its combination of prominent sheath auricles, with abundant radiate fimbriae, small foliage leaf blades, and awnless spikelets.  相似文献   

15.
Prochristianella spinulifera n. sp. (Cestoda: Trypanorhyncha: Eutetrarhynchidae) is described from the spiral valves of the rays Rhinobatos typus (Rhinobatidae) and Himantura fai (Dasyatidae) from Heron Island, Queensland, Australia. The new species is distinguished from all congeners by the deltoid microtriches covering the anterior 80% of the scolex and the presence of a dorsoventrally elongate genital atrium. The species occurred in the anteriormost section of the spiral valve of R. typus. The orientation of the armature of this and other congeners is such that principal rows of hooks begin on the bothridial surface of the tentacle and end on the antibothridial surface.  相似文献   

16.
Knodus dorsomaculatus, a new species, is described from Teles Pires River, a tributary of the Tapajós River, Brazil. It can be distinguished from its congeners by the presence of a conspicuous dark blotch on the base of the first five branched dorsal fin rays and the presence of ii,9 dorsal fin rays. Additional comparisons between K. dorsomaculatus and its congeners are presented.  相似文献   

17.
A new species of the genus Leptolalax is described from Doi Saket, Chiang Mai Province, northern Thailand. The new species is distinguished from its congeners by the following combination of characters: 1) adult size large(male SVL 45.8-52.5 mm); 2) tympanum distinct; 3) skin of dorsal surface mostly smooth, with distinct tubercles on dorsal and lateral parts of the body; 4) ventrolateral glandular ridge distinct and complete; 5) lateral body and groin covered with dark brown or black spots; 6) throat, chest, and belly nearly immaculate white; and 7) bi-colored iris, upper onethird golden, and lower two-thirds gray. Molecular phylogenetic analysis of mitochondrial 16S rRNA further distinguishes it from its congeners for which sequences are available.  相似文献   

18.
The species Branchinecta granulosa Daday 1902, is redescribed on the basis of adult material from near Facundo (Chubut Province, Argentina). Its relationship to its regional congeners is outlined.  相似文献   

19.
A new species, Theridion longipili sp. nov. (Theridiidae), is described from Korea. It is easily distinguished from other congeners by the structure of conductor, radix, median apophysis, and the female epigynum and internal genitalia.  相似文献   

20.
《Journal of bryology》2013,35(3):177-181
Abstract

Jonesiobryum dumboi is described as a new moss species from Uganda. It differs from its congeners by possessing more broadly obovate leaves and a costa that ends well below the apex. The species is only known from the type locality where it was collected on branches in the canopy.  相似文献   

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