首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
The systematic relationships of the snake genus Anomochilus   总被引:1,自引:1,他引:1  
Phylogenetic analysis of 38 skeletal characters, 12 muscular characters and 15 visceral characters in 17 major snake clades plus Anomochilus suggests that Anomochilus is the sister taxon of all other living alethinophidian snakes. However, skeletal, muscular and visceral character sets analysed separately or in pairs give four groups of nonconcordant tree topologies. Based on the cladogram derived from the total evidence, two families are erected to prevent the existing family Uropeltidae from becoming paraphyletic: Anomochilidae, for the Malaysian and Indonesian genus Anomochilus , and Cylindrophiidae, for the Sri Lankan, Southeast Asian and Indonesian genus Cylindrophis and the Upper Eocene fossil Eoanilius.  相似文献   

2.
The sporadic occurrence of localised pits on parietal plates was recently discovered in different colubrid genera of the subfamily Psammophiinae; these were considered to play a role in sensory perception. In the present study, we describe the presence of similar structures in Atretium schistosum, another colubrid snake reportedly not belonging to the Psammophiinae. As this species is suspected of being phylogenetically distantly related to psammophine snakes, some hypotheses are provided to explain (1) the putative function of these pits, (2) their sporadic occurrence, and (3) to suggest when they may have evolved in the colubroid snake clade.  相似文献   

3.
    
Elapids, viperids, and some other groups of colubroid snakes have tubular fangs for the conduction of venom into their prey. The literature describing the development of venom-conducting fangs provides two contradictory accounts of fang development. Some studies claim that the venom canal forms by the infolding of a deep groove along the surface of the tooth to produce an enclosed canal. In other works the tubular fang is said to form by the deposition of material from tip to base, so that the canal develops without any folding. This study was undertaken to examine fang development and to account for the disagreement in the literature by determining whether fang formation varies among groups of venomous snakes and whether it differs between embryos and adults. Adult and embryonic representatives of elapids and viperids were examined. All fangs examined, elapid and viperid, embryos and adults, were found to develop into their tubular shape by the addition of material to the basal end of the tooth rather than by the folding inward of an ungrooved tooth to form a tubular fang. In some cases, the first fang that develops in embryonic snakes differs morphologically from all those formed subsequently.  相似文献   

4.
    
The cranial anatomy of Dinilysia patagonica, a terrestrial snake from the Upper Cretaceous of Argentina, is redescribed and illustrated, based on high‐resolution X‐ray computed tomography and better preparations made on previously known specimens, including the holotype. Previously unreported characters reinforce the intriguing mosaic nature of the skull of Dinilysia, with a suite of plesiomorphic and apomorphic characters with respect to extant snakes. Newly recognized plesiomorphies are the absence of the medial vertical flange of the nasal, lateral position of the prefrontal, lizard‐like contact between vomer and palatine, floor of the recessus scalae tympani formed by the basioccipital, posterolateral corners of the basisphenoid strongly ventrolaterally projected, and absence of a medial parietal pillar separating the telencephalon and mesencephalon, amongst others. We also reinterpreted the structures forming the otic region of Dinilysia, confirming the presence of a crista circumfenestralis, which represents an important derived ophidian synapomorphy. Both plesiomorphic and apomorphic traits of Dinilysia are treated in detail and illustrated accordingly. Results of a phylogenetic analysis support a basal position of Dinilysia, as the sister‐taxon to all extant snakes. The fossil taxa Yurlunggur, Haasiophis, Eupodophis, Pachyrhachis, and Wonambi appear as derived snakes nested within the extant clade Alethinophidia, as stem‐taxa to the crown‐clade Macrostomata. The hypothesis of a sister‐group relationship between Dinilysia and Najash rionegrina, as suggested by some authors, is rejected by the results of our analysis. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 164 , 194–238.  相似文献   

5.
The generic name Urotheca Bibron, 1843 is revived for a group of Neotropical colubrid snakes diagnosed by a long, thickened but fragile tail and the presence of a specialized naked pocket on the asulcate surface of the hemipenial capitulum. Urotheca includes those species previously placed in the lateristriga group of the genus Rhadinaea and the coral snake mimics usually referred to the genus Pliocercus. The many names based upon the coral snake mimics are shown to represent two species at most: Urotheca elapoides, a bicolour (red and black) or tricolour (red, yellow and black) banded or ringed form found in Mexico and northern Central America and U. euryzona, which is usually bicolour (red, yellow or white and black) and ranges from Nicaragua to western Ecuador. Coloration in U. elapoides resembles closely that of sympatric species of venomous coral snakes. Local variation in coloration and a geographic trend in the colour of the light rings (usually red in the north, white to the south) in U. euryzona parallels similar colour variation in the sympatric venomous coral snake Micrurus mipartitus. These patterns of variation add strong support to the idea that the two species are mimics of the highly venomous coral snakes. Urotheca, including the non-mimetic species U. decipiens, U. fulmceps, U. guentheri, U. lateristriga, U. multilineata and U. pachyura, shares the characteristic of a very long and disproportionately thickened and fragile tail with the coral snake mimics of the distantly related genus Scapkiodontophis. Members of both genera have a very high proportion (about 50%) of the tails broken indicating a probable predator escape device. Breakage is intercentral, with a calcified cap developing over the tip of the distal surface of the new terminal vertebra unlike the situation in many lizards where there is an intracentral fracture septum and the tail is regenerated.  相似文献   

6.
    
Relationships among families of the shark order Carcharhiniformes are still being debated, for example, in relation to the inclusion of hammerhead sharks (Sphyrnidae) and the tiger shark (Galeocerdo cuvier) in the Carcharhinidae. Previous morphological studies have not analyzed the phylogenetic significance of axial caudal muscles among carcharhiniforms. The authors therefore describe here the axial muscles of the tail region (m. epaxialis, m. obliquus superioris, m. obliquus inferioris, m. flexor caudalis) to better understand their anatomical patterns among carcharhiniform sharks. Our results indicate that the family Pentanchidae, recently separated from scyliorhinids (catsharks), present a similar pattern of caudal muscles to catsharks, indicating their close phylogenetic relationship. Triakids, hemigaleids, leptochariids, Galeocerdo cuvier and Prionace glauca have a unique pattern in which the medial axial bundle is bulkier than all other caudal axial muscles. Sphyrnids share with carcharhinids a similar pattern of the m. obliquus superioris (approximately the same size as the dorsal m. epaxialis) and have fibers of the m. flexor caudalis arranged in a V-shape. This chevron-shape is also present on the m. flexor caudalis of hemigaleids and leptochariids. Also, sphyrnids and carcharhinids have more slender septa between muscle bundles (more notably in carcharhinids; the only exception is Galeocerdo cuvier, which has the same pattern as sphyrnids). Although being used here as an outgroup, Squaliformes is unique in lacking one of the epaxial bundles. The authors conclude that the caudal axial musculature has greater phylogenetic potential than previously understood.  相似文献   

7.
    
Geophis belongs to the goo‐eating dipsadine assemblage of snakes that are known to feed exclusively on earthworms, snails, and slugs. Although the unusual feeding strategies of the goo‐eating dipsadines are well known (but poorly documented), little attention has been paid to their internal anatomy. Here, we describe a new and noteworthy morphological and histochemical condition of the infralabial glands in three species of Geophis (G. brachycephalus, G. nasalis and G. semidoliatus), all earthworm feeders. Their infralabial glands are constituted of two distinct parts: an anterolateral portion composed of mucous and seromucous cells that stretches from the tip of the dentary to the corner of the mouth, and a tubular posteromedial portion that is exclusively seromucous. The anterolateral portion receives fibers of the levator anguli oris muscle that attaches on its posterodorsal extremity while the posteromedial portion extends posteriorly to the corner of the mouth where it receives fibers of the adductor mandibulae externus medialis muscle. Furthermore, the posteromedial portion of the infralabial gland is constituted by large acini filled with secretion that is periodic acid‐Schiff positive. These acini release their secretion directly into a large lumen located in the middle of the glandular portion. In the three species examined, the supralabial glands show a traditional configuration, being constituted of mucous and seromucous cells and retaining an enlarged part in its caudal region that resembles a Duvernoy's gland. The presence in Geophis of an expanded lumen in part of the infralabial gland that is compressed by an adjacent muscle suggests a more specialized role for the secretion produced by these glands that may not be related to envenomation but rather to prey transport and mucus control. J. Morphol. 275:87–99, 2014. © 2013 Wiley Periodicals, Inc.  相似文献   

8.
任国栋  刘春林 《昆虫学报》2009,52(10):1146-1155
基于18个代表种的防御腺特征, 探讨了中国刺甲族(Platyscelidini)4个属的分类地位和系统发育关系。通过对防御腺的着生位置、形状及其长度和宽度、腺体间距及其表面花纹和皱褶等重要特征的分析, 归纳出属级和族级的防御腺特征。利用SPSS 13.0和Hennig 86(1.5)2个软件对所选定的防御腺特征分别进行聚类分析和进化分析, 两者结果均支持刺甲族现有分类体系的稳定性, 且后者提出刺甲族4属的系统发育关系为: (Myatis +Bioramix)+(Oodescelis + Platyscelis)  相似文献   

9.
The male genitalia of 107 spider species representing 73 families were serially sectioned and studied with an emphasis on muscles moving the genital bulb. As a rule, most non-Entelegynae have two bulbal muscles, most Entelegyne have none, but many exceptions occur. Variation also occurs with regard to origin and attachment of bulbal muscles. There appears to be a trend towards a shift of the origin from proximal (Liphistius, Atypus) to more distal palpal segments (Haplogynae). In most Entelegynae the muscular movement is replaced by hydraulic movement caused by expanding membranes (hematodochae). Hematodochae probably permit increased bulbal rotation and movements of higher complexity. New evidence is presented arguing against Palpimanidae being representatives of Entelegynae. Bulbal glands other than those discharging into the sperm duct (previously known in Amaurobiidae and Dictynidae only) are described in several entelegyne families.  相似文献   

10.
11.
The characters of the genitalia of the females of Glyptotendipes glaucus (Meigen, 1818), Glyptotendipes pallens (Meigen, 1804), Glyptotendipes paripes (Edwards, 1929), Glyptotendipes gripekoveni (Kieffer, 1913), Glyptotendipes aequalis (Kieffer, 1922), Glyptotendipes barbipes (Staeger, 1839) and Glyptotendipes salinus Michailova, 1987 are described. A key for the identification of these species is given.The taxonomic status of Glyptotendipes aequalis is discussed.  相似文献   

12.
13.
The genus Adeonella Busk (1884) comprises 41 species, 15 of which are considered to be new to science. Adeonella lichenoides (Lamarck) is regarded as the senior synonym of A. platalea (Busk) (= A. polymorpha Busk), the type species of the genus. Adeonella is distributed throughout the Indo-West Pacific realm, the Mediterranean, and the South Atlantic Ocean. Its highest diversity is found off the east coasts of southern Africa. Thirty-one species (15 new to science) are described and illustrated, morphology and geographical distribution are discussed and a key is provided to all recognized species.  相似文献   

14.
15.
    
Summary

Time to pupation, percent survival to pupation, and percent adult emergence of Anopheles albimanus Wiedemann decreased at higher larval rearing temperature. Mosquitoes reared at 30°C experienced higher mortality during the pupal stage than did mosquitoes reared at 22°C. Analysis of variance revealed that wing length and costal wing spot patterns of adult female A. albimanus were affected by larval rearing temperature. Female A. albimanus reared at 22°C had longer wings, and larger basal pale + prehumeral pale, prehumeral dark, and humeral pale costal wing spots than did female siblings reared at 30°C. Female A. albimanus reared at 30°C had larger subcostal pale spots than did female siblings reared at 22°C. Analyses of 2x2 contingency tables indicated that sex ratio was independent of larval rearing temperature, whereas survival to the adult stage and coalescence of wing spots were not independent of rearing temperature. The need to examine stability of morphological characters under differing environmental conditions is discussed.  相似文献   

16.
    
Flight is the overriding characteristic of birds that has influenced most of their morphological, physiological, and behavioral features. Flight adaptations are essential for survival in the wide variety of environments that birds occupy. Therefore, locomotor structure, including skeletal and muscular characteristics, is adapted to reflect the flight style necessitated by different ecological niches. Red-tailed hawks (Buteo jamaicensis) soar to locate their prey, Cooper's hawks (Accipiter cooperii) actively chase down avian prey, and ospreys (Pandion haliaetus) soar and hover to locate fish. In this study, wing ratios, proportions of skeletal elements, and relative sizes of selected flight muscles were compared among these species. Oxidative and glycolytic enzyme activities of several muscles were also analyzed via assays for citrate synthase (CS) and for lactate dehydrogenase (LDH). It was found that structural characteristics of these three raptors differ in ways consistent with prevailing aerodynamic models. The similarity of enzymatic activities among different muscles of the three species shows low physiological differentiation and suggests that wing architecture may play a greater role in determining flight styles for these birds.  相似文献   

17.
Phylogenetic relationships of the subgenera of Exorista Meigen (Diptera: Tachinidae) are inferred from morphological data. Our results show that the genus Exorista is not monophyletic and that members of the subgenus Spixomyia Crosskey are divided into two clades. Each subgenus is redefined based on male and female morphological features. The Japanese species of Exorista are revised and classified into five subgenera: Adenia Robineau‐Desvoidy, Exorista Meigen, Podotachina Brauer and Bergenstamm, Ptilotachina Brauer and Bergenstamm, and Spixomyia Crosskey. Thirteen species are recognized, including two newly recorded species, Exorista (Adenia) cuneata Herting and Exorista (Spixomyia) lepis Chao. Exorista cantans Mesnil is transferred to the subgenus Podotachina from Spixomyia.  相似文献   

18.
In the past, the two species of Courtoisina were placed either in Cyperus L., Mariscus Vahl, or in Courtoisia Nees (now Courtoisina Sojak). While these species show undoubted external similarities to both Cypm and Muriscus , they differ by their widely winged glumes and the arrangement of the veins of the glumes. They also differ profoundly from Mariscus and most species of Cypm in anatomical characteristics, and it is concluded that these differences warrant separate generic status.  相似文献   

19.
    
A re-evaluation of Minuartia graminifolia has been undertaken based on comparative morphological studies. M. graminifolia subsp. rosani (an endemic of the south-central Apennines and Sicily) and subsp. hungarica (an endemic of the Banat region of Romania) are accepted infraspecific taxa. M. graminifolia subsp. hungarica is lectotypified. M. graminifolia subsp. clandestina is confirmed for Italy; the taxon is neotypified. The type subspecies is considered an endemic to the east-central Alps. Keys to the species of Minuartia ser. Graminifoliae and to the subspecies of M. graminifolia are provided.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 143 , 419–432.  相似文献   

20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号