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Frank Almeda 《Brittonia》1990,42(1):7-11
Tessmannianthus cereifolius, a new species from eastern Panama, is described, illustrated, and compared to its closest presumed relative,T. heterostemon of Ecuador and Peru. The new species is distinguished by its truncate calyx, absence of exterior calyx teeth, and complete glabrosity. A 5-celled ovary is reported for the first time inT. cereifolius andT. heterostemon. The latter was previously thought to be characterized by a trilocular ovary. A distribution map and a revised key to the three Panamanian species ofTessmannianthus are also provided.  相似文献   

3.
Abstract:  Upper Jurassic (Tithonian) deposits in north‐western Patagonia, Argentina, have yielded rich and taxonomically diverse assemblages of marine reptiles. These assemblages are also remarkable by their quality of preservation and are represented by ichthyosaurs, plesiosaurs, turtles and crocodyliforms. Despite the abundant crocodyliform record, only two metriorhynchid taxa have been identified: Cricosaurus araucanensis and Dakosaurus andiniensis. Here we described a new species of Cricosaurus, which represents the second species of Cricosaurus in the Tithonian of the Neuquén Basin, and the first metriorhynchid found in lithographic limestone from Gondwana. Furthermore, this specimen has the most complete postcranial remains of any metriorhynchid from South America. The new species is characterized by a short distance between the premaxilla and the nasal, a relatively narrow interorbital width, 23–25 mandibular teeth, bicarinated teeth with fine apicobasally aligned ridges, interalveolar spaces between the first seven teeth approximately 1.5 times longer than the anteroposterior diameter of the respective alveoli. To test the assignment of the new species to Cricosaurus, we carried out two phylogenetic analyses. In both analyses, Cricosaurus lithographicus sp. nov. is nested with other species referred to this genus. This new species has peculiar enamel ornamentation, characterized by numerous, fine apicobasally aligned ridges, when compared to other species of the genus.  相似文献   

4.
Three trophic categories exist within emperor fishes, genus Lethrinus, relating to body form and dentition type. One group contains low-bodied, high speed, stalking predators with conical teeth. Another group comprises high-bodied, slow speed carnivores with molariform teeth capable of crushing hard-shelled benthic prey. A third group is also high-bodied but with conical teeth feeding mostly on small or soft-shelled benthic prey. Inferring the evolution of these trophic types within Lethrinus using morphology is problematic since these characters are typically correlated with feeding mode and are potentially homoplasious. We use mitochondrial DNA sequences, to independently determine a phylogenetic hypothesis for Lethrinus, which are not dependent on morphological characters relating to trophic categories. We analyzed complete cytochrome b gene sequences (1140 bp) for 20 species of Lethrinus, representing the three trophic types, and for 13 outgroup species, including four other representatives of the Lethrinidae. A monophyletic Lethrinidae did not resolve, but the monophyly of Lethrinus is well supported. In addition, two major clades within Lethrinus are well supported. One of these clades exclusively contains low-bodied species with conical teeth while the other clade only comprises the high-bodied species with molariform teeth. A high-bodied species with conical teeth, Lethrinus miniatus, appears most ancestral and sister to all other Lethrinus species. We hypothesize that this generalist trophic type was the evolutionary precursor to both of the other primary trophic types.  相似文献   

5.
河北蔚县早更新世哺乳动物化石及其在地层划分上的意义   总被引:9,自引:2,他引:7  
蔚县东陡壁早更新世哺乳动物化石地点所发现的化石,虽然数量和种类不多,但有一些比较原始的类型。这些第三纪晚期的残留属一直延续生存到第四纪初,并作为第四纪早期哺乳动物群的重要成员。这些新材料的发现,对泥河湾动物群是一个新的补充,并可作为泥河湾地区早更新世地层进一步划分和对比的可靠依据。  相似文献   

6.
A new species of Hypostomus with spoon-shaped teeth is described from the Rio Cupari basin, a right margin affluent of the lower Rio Tapajós, Pará State, Brazil. The new species inhabits rocky bottom areas in the main channel of Rio Cupari and its tributaries. The new species can be distinguished from all its congeners, except from the Hypostomus cochliodon group, by having six to eight spoon-shaped teeth, dentaries angled at less than 80° and the absence of a notch between the hyomandibular and the metapterygoid. The new species is distinguished from all species of the H. cochliodon group by its unique colour pattern, containing dark vermiculations on head and anterior portion of the trunk, and by the absence of medial buccal papillae.  相似文献   

7.
准噶尔盆地克拉美丽地区的鸟脚类   总被引:3,自引:3,他引:0  
本文记述了一个小型鸟脚类——五彩湾工部龙(新种)Gongbusaurus wucaiwanensis sp.nov.,讨论了它们的分类位置和产出地层时代。  相似文献   

8.
A large set of South American fossils belonging to the genus Tapirus has been described on the basis of differences in size and proportions of lower molariform teeth. Nevertheless, the reliability of dental proportions for the diagnosis of fossil tapir species is controversial. In this paper, we describe new fossil material of Tapirus from the Quaternary of Serra da Bodoquena, Southwestern Brazil, comparing it to other fossil and extant specimens of the genus by means of multivariate morphometric analyses of lower molariform teeth linear dimensions. The results of Principal Component Analyses indicate that some of the extant and extinct material attributed to Tapirus fall within the range of variation in size and proportions of lower molariform teeth exhibited by recent species of the genus. Therefore, part of the fossil material attributed to new species or to Tapirus sp. may be referable to the extant species Tapirus terrestris. We conclude that the sole use of lower molariform teeth size and proportions to erect new species of Tapirus may not be reliable, and therefore we advocate caution when describing fossil tapirs exclusively based on these criteria.  相似文献   

9.
长有德  贺达汉 《昆虫学报》2002,45(Z1):110-111
 记述了采自甘肃平凉(崆峒山)的光胸臭蚁一新种,齿颚光胸臭蚁Liometopum dentim andibulum sp. Nov. 。模式标本保存在宁夏大学农学院标本室。  相似文献   

10.
长有德  贺达汉 《昆虫学报》2002,45(2):110-111
记述了采自甘肃平凉(崆峒山)的光胸臭蚁一新种,齿颚光胸臭蚁Liometopum dentim andibulum sp. Nov. 。模式标本保存在宁夏大学农学院标本室。  相似文献   

11.
A new species of Megaleporinus is described from the Rio de Contas, a coastal drainage of eastern Brazil, and its phylogenetic relationships are studied using molecular data. The new species is unique among Anostomidae by possessing two exclusive features: an irregular dark longitudinal stripe from supracleithrum to second midlateral blotch and anterior cranial fontanel partially closed. In addition, the new species is diagnosed by having three premaxillary teeth, three dentary teeth, 37 or 38 scales in lateral line, 16 scale rows around caudal peduncle, three dark midlateral blotches on body, and red fins in life. The new species is closely related to M. obtusidens from the São Francisco basin, corroborating previous studies that indicated that the latter represents a species complex as currently defined. The new species exhibits the first rib enlarged in mature males, a feature described for some congeners. The new species is herein considered to be Endangered under the IUCN criteria.  相似文献   

12.
本记述了中国革腹茧蜂属Ascogaster一新种皱纹革腹茧蜂Ascogaster retis Ji et Chen,sp,nov.,新种主要特征是:体黑色;触角中部稍膨大,头顶具横向网状皱;背面观,上颊约与复眼等长,额与复眼缘之间具纵向网状皱;脸具粗糙网状皱;唇基具中度密集的刻点,端缘中央具一钝突,盾纵沟甚浅,中胸侧板具孔穴状刻点,无基节前沟,并胸腹节具明显的四齿,侧齿大,中齿小;甲壳末端具与体平行的短棘,产卵器鞘较短,不超出腹末,本新种与Ascogaster fullawayi(Baker)相似,但新种额两侧边缘中间与复眼缘之间无角状齿,脸下部的网状皱不形成弱纵脊,脸部毛短且稀疏,宙末端棘短而钝,该新种模式标本保存于福建农林大学益虫研究室。  相似文献   

13.
The aim of this study was to investigate retention of composite fissure sealant polymerized with standard and soft-start technique after a three year clinical trial. One hundred teeth were divided into two groups (A&B) of teeth and sealed with composite material (Visioseal, 3M Espe) using split mouth design. Sealants were polymerized using standard (Group A) and soft-start (Group B) techniques with commercial polymerization unit (Elipar Highlight, 3M Espe). Retention rate in Group A was 72%. In 14 teeth sealant was partially or completely missing. Group B showed retention rate of 80%. Sealant was partially or completely missing in 10 teeth. Six new caries lesions in Group A (3) and B (3) were detected. Mann-Whitney test did not reveal significant differences between the polymerization techniques. After three years complete retention of sealants, regardless of the group, was 76% (76 teeth) with six new caries lesions. Soft-start polymerization showed a comparable retention rate as the standard polymerization technique.  相似文献   

14.
An analysis with SEM of the mouth parts of 16 species belonging to 10 genera of Gnathostomulida resulted in the following new characters and conclusions: 1) At least in the genus Haplognathia, jaw teeth that are visible by conventional light microscopy are composed of the same aggregated needle-like denticles that are found, often in large numbers, on the basal plates of many filospermoid species. 2) Other new ultrastructural tooth features include the tricuspid basal plate teeth in Problognathia minima, tripartite teeth in Austrognathia and Austrognatharia, and the clear separation, in the Gnathostomula basal plate, of a mediodorsal set of teeth from a more extensive rostroventral set. 3) Three rows of teeth, as typical for Gnathostomulidae and Austrognathiidae, are also present in the filospermoid Haplognathia filum. 4) The wide range of geographic variation in Haplognathia ruberrima is confirmed by significant differences in jaw teeth between specimens from Belize and Bermuda. 5) A compartmentalized involucrum is present in Labidgonathia longicollis. 6) A pair of lamellae addentales, until now only known from Valvognathia pogonostoma, was found in Tenuignathia rikerae, Problognathia minima, and probably also Labidognathia rikerae. 7) In all gnathostomulids, the lamella symphysis is composed of identical rods that are considered homologous with those in the mouth parts of Rotifera and Micrognathozoa.  相似文献   

15.
在云南腾冲采到稻蝗属1新种,郑氏稻蝗Oxya zhengisp.nov.。新种近似于小稻蝗Oxya intricata (Stl),主要区别:1)雌雄个体均较粗壮,前翅短,仅到达后足股节中部;2)雄性中胸腹板侧叶间中隔较狭,长为宽的3倍;3)雌性下产卵瓣外缘无明显突出的钝齿,仅具细齿;4)雄性阳茎基背片内冠突较大,呈三角形。  相似文献   

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对颚毛虫兆属Crossodonthina Yosii, 1954做了简要介绍,提供了该属的鉴别特征,记述了采自中国湖南省东安县舜皇山的颚毛虫兆属1新种——周氏颚毛疣虫兆Crossodonthina choui,这是该属在华中地区(湖南)的新记录。新种的正模标本(♂)和2个副模标本(2♂)保存在中南林业科技大学生命科学与技术学院昆虫标本室。  相似文献   

18.
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   

19.
A new species of the genus Grammatonotus from the western part of the Pacific Ocean (the region of the Hawaiian Islands) is described. From all previously known species of this genus, G. ambiortus sp. nova differs in multiserial teeth and the absence of canine teeth on praemaxillaria. The structure of its caudal skeleton is also different from most species (except G. macrophthalmus from the Kyusyu-Palau Ridge); moreover it is differentiated by a large eye.  相似文献   

20.
记述了采集于云南蒙自匙指虾科米虾属1新种,贫齿米虾Caridina paucidentata sp.nov..文中详细描述了其形态特征,同时附特征图.新种和近似种蒙自米虾的主要区别在于前者额角背缘齿少,仅1~3个.模式标本保存于上海水产大学.  相似文献   

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