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1.
2.
A new species of mudskipper,Periophthalmus spilotus, is described on the basis of 16 specimens from Sumatra, Indonesia. It differs from other species ofPeriophthalmus by the following combination of characters: pelvic fins totally united into rounded disk; first dorsal fin high, greyish, no spots on fin nor elongate spines; second dorsal fin typically with 14 total elements; anal fin typically with either 14 or 15 total elements; length of anal-fin base 21.8–29.0% SL; and length of second dorsal-fin base 22.5–26.7% SL. This species is most similar to, and probably most closely related to,P. chrysospilos.  相似文献   

3.
WithAcanthodes boyi n. sp. another new species of acanthodians from the Saar - Nahe -Basin is described. Only the holotype is known. The specimen differs in several characteristics such as stages of ossification, vertebral column, development of the shoulder girdle, development of the fin spines, and other details from both known species,Acanthodes bronni (Agassiz) andAcanthodes tholeyi (Heidtke).  相似文献   

4.
The new pycnodont fishAnomoeodus pauciseriale is described. The single specimen consists of associated but disarticulated skeletal remains including the paired prearticulars, some skull elements, remains of the pectoral girdle and the vertebral column. It comes from the White Chalk Formation (Upper Cretaceous) of East Sussex near Lewes, England. The precise stratigraphic age and locality are not known. The specific identification is based on characters of the prearticular dentitions because the other skeletal remains are not diagnostic. In contrast to other species ofAnomoeodus, the new species is characterised by a combination of rather short prearticular dentitions with only four tooth rows, a comparable low number of medial teeth, and the absence of intercalated teeth between tooth rows.   相似文献   

5.
Acipenseriformes hold an important place in the evolutionary history of bony fishes. Given their phylogenetic position as extant basal Actinopterygii, it is generally held that a thorough understanding of their morphology will greatly contribute to the knowledge of the evolutionary history and the origin of diversity for the major osteichthyan clades. To this end, we examined comparative developmental series from the pectoral girdle in Acipenser fulvescens, A. medirostris, A. transmontanus, and Scaphirhynchus albus to document, describe, and compare ontogenetic and allometric differences in the pectoral girdle. We find, not surprisingly, broad congruence between taxa in the basic pattern of development of the dermal and chondral elements of the pectoral girdle. However, we also find clear differences in the details of structure and development among the species examined in the dermal elements, including the clavicle, cleithrum, supracleithrum, posttemporal, and pectoral‐fin spine. We also find differences in the internal fin elements such as the distal radials as well as in the number of fin rays and their association with the propterygium. Further, there are clear ontogenetic differences during development of the dermal and chondral elements in these species and allometric variation in the pectoral‐fin spine. The characters highlighted provide a suite of elements for further examination in studies of the phylogeny of sturgeons. Determining the distribution of these characters in other sturgeons may aid in further resolution of phylogenetic relationships, and these data highlight the role that ontogenetic and comparative developmental studies provide in systematics. J. Morphol. 276:241–260, 2015. © 2014 Wiley Periodicals, Inc.  相似文献   

6.
7.
The latest works on iniopterygians question their monophyly when considering only the neurocranium of the two families (Sibyrhynchidae and Iniopterygidae), which have different conditions of preservation. Some of the synapomorphies of the Iniopterygia concern the pectoral girdle and fins. However, the anatomy of these different elements is still poorly known in this taxon. Here we describe in details three dimensionally preserved cartilages of the pectoral girdle and fins of the sibyrhynchid Iniopera sp. These structures have been extracted virtually from phosphatised nodules thanks to conventional and synchrotron microtomography, using absorption and phase contrast based techniques in the later case. The pectoral girdle of Iniopera sp. consists of three elements, which are, from dorsal to ventral, a paired suprascapular cartilage, a pair of robust scapulocoracoids and an unpaired intercoracoid cartilage. The scapular part of the scapulocoracoids is extremely reduced and the suprascapular cartilages link the scapulcoracoids to the rear of the neurocranium. These characters may be iniopterygian synapomorphies. Iniopterygians, stem and crown-holocephalans share a basipterygium that articulates with the pectoral girdle and bears an enlarged first pectoral fin radial. Posteriorly, the basipterygium articulates with either a well-defined metapterygium (in crown-holocephalans) or a metapterygial axis (in stem-holocephalans).  相似文献   

8.
The endoskeletal girdles, anocleithrum and paired fin supports of the porolepiform fish Glyptolepis (Osteichthyes: Sarcopterygii: Porolepiformes) are figured and described. The pectoral fin skeleton is known from the proximal part only and the pelvic fin skeleton is fragmentary, but the scapulocoracoid, anocleithrum and pelvic girdle can be reconstructed in their entirety. The anocleithrum is entirely subdermal. The pectoral fin skeleton in shown to be biserial, with a large number of axial mesomeres, whereas the pelvic fin contains fewer mesomeres and is strongly asymmetrical with very few postaxial radials. The scapulocoracoid is essentially similar to a reconstruction figured by Jarvik (1980), but has a more elongate glenoid; this has functional implications. The pelvic girdle consists of two separate halves as in Eusthenopteron, but differs from that genus in lacking dorsolateral rami. A brief survey of the evidence of paired fin structure in other porolepiform genera is carried out to establish whether the structures seen in Glyptolepis are likely to be representative for the Porolepiformes. A study of the morphology and muscle attachments of the paired fin skeletons indicates that the pattern of fin movement was significantly different from that in Neoceratodus. The fin supports and girdles of Glyptolepis are compared with those of other sarcopterygian groups as well as with actinopterygians, placoderms and sharks, in order to establish evolutionary polarities. Glyptolepis is shown to display a number of derived characters. The information gained from the comparison is used to construct a maximum parsimony cladogram, which places coelacanths as the sister group of porolepiforms + lungfishes, with the rhizodonts + tetrapods and osteolepiforms as successive sister groups of this clade. Characters of uncertain polarity are considered in the light of this cladogram. A comparison with recently published cladograms shows that none are completely compatible with the results from this study.  相似文献   

9.
湘西溶溪组的棘鱼化石及其层位   总被引:5,自引:1,他引:4  
本文介绍了目前我国最低含鱼化石地层,即湘西早志留世(Llandovery 期)溶溪组的地区性地质剖面和产自该组七个类型的棘鱼鳍刺化石,并根据其同层中所产的无脊椎动物化石论证鱼化石层的层位.鱼化石本身所表现出的原始特性与这一结论是谐调的.  相似文献   

10.
Characidium iaquira, a new species from the upper rio Juruena, rio Tapajós basin, Brazil, is described. The new species can be promptly distinguished from all congeners by having a unique v-shaped dark mark lying along the caudal-fin extension, in medium- and large-sized specimens, and a remarkable iridescent green colouration in life. Characidium iaquira is closely related to Characidium crandellii and Characidium declivirostre by sharing unambiguous synapomorphies such as branchiostegal membranes united to each other across the isthmus, a scaleless area extending from the isthmus to the pectoral girdle, and dermal flaps surrounding anterior and posterior naris independent, but touching each other distally. Morphological specializations of the paired fins in the three riffle-dwellers species are discussed, including the wing-like shape, robustness, and inclination of the pectoral fin.  相似文献   

11.
记比耶鱼(Birgeria)在中国的首次发现   总被引:4,自引:0,他引:4  
金帆 《古脊椎动物学报》2001,39(3):168-176,T001,T002
记述了采自云南罗平晚三叠世法郎组竹杆坡段的比耶鱼一新种──刘氏比耶鱼(Birgeria liui sp. nov.),这是比耶鱼化石在中国的首次发现。刘氏比耶鱼与产自瑞士圣乔治山中三叠世边境沥青层的史氏比耶鱼最为相近,两者仅在尾柄长高之比、尾鳍长短与上下叶外缘交角、背鳍和臀鳍辐状支鳍骨的数目、臀鳍辐状骨骨板的大小、以及侧线管骨化与否等特征上略有差异。比耶鱼与软骨硬鳞鱼超目的鲟形目最为接近,两者共有一系列特征,如除尾上叶外体侧裸露,副蝶骨末端伸达头后,鳃盖骨退化;但比耶鱼同时也具有不少的特有特征,代表了软骨硬鳞鱼超目的另一类群──比耶鱼目(Birgeriiformes ord. nov.)。刘氏比耶鱼的发现进一步表明华南扬子区中、晚三叠世鱼类化石与特提斯西部的鱼群具有密切的动物地理关系。  相似文献   

12.
A new chimaerid species closely related to Hydrolagus pallidus is described from 13 specimens captured on the Portuguese continental slope (north‐east Atlantic) by commercial longliners at depths of c . 1600 m. The new species is large‐bodied with a rose to light brown body colouration. Hydrolagus lusitanicus n.sp. presents a combination of external morphological characters that allow it to be clearly differentiated from its congeners, in particular, the ratios of pectoral fin length: pectoral fin width and pelvic fin length: pelvic fin width; in having a serrated posterior edge of the dorsal spine; a high number of ridges in the dental plates. Additionally in males, there are differences on the shape and number of hooks in the frontal tenacula, on the number of spines in the prepelvic tenacula and on the length of the pectoral fin margin.  相似文献   

13.
A new species of the dinoflagellate genus Cachonina, C. illdefina sp. nov., was isolated from a red tide off El Capitan State Park, Santa Barbara County, California, in October 1973. The organism is light yellowgreen in color with deeply incised girdle and sulcal grooves. Electron microscopy of the organism, revealed a typical dinokaryotic nucleus. The chloroplasts of the organism are connected, and often contain microtubule-like elements, 25 nm diam. The pyrenoids are characterized as excluding chloroplast thylakoids and ribosomes, although containing an amorphous matrix and numerous tubular invaginations from the cytoplasm. The pyrenoids become detached from the chloroplasts and degenerate into small vesicles. C. illdefina is not bioluminescent.  相似文献   

14.
A new species of tripterygiid fish, belonging to the recently described genusCeratobregma Holleman, 1987, is characterized by a total of 17 spines in the second dorsal fin, 8 rays in the third dorsal fin, 20 anal fin rays (spines+rays = 22), 14 + 21 lateral line scales, a total of 35–37 lateral scale series, small spiny scales on the sides of the head behind the eye and on the upper cheeks, 14 vertical dark stripes along the upper sides of the body, and 8 basal blotches on the second dorsal fin. A key to the species ofCeratobregma is presented.Norfolkia brachylepis is described and recorded from northwestern Australia.Norfolkia springen is synonymized withN. brachylepis.  相似文献   

15.
Zhu M  Yu X  Choo B  Qu Q  Jia L  Zhao W  Qiao T  Lu J 《PloS one》2012,7(4):e35103

Background

The pectoral and pelvic girdles support paired fins and limbs, and have transformed significantly in the diversification of gnathostomes or jawed vertebrates (including osteichthyans, chondrichthyans, acanthodians and placoderms). For instance, changes in the pectoral and pelvic girdles accompanied the transition of fins to limbs as some osteichthyans (a clade that contains the vast majority of vertebrates – bony fishes and tetrapods) ventured from aquatic to terrestrial environments. The fossil record shows that the pectoral girdles of early osteichthyans (e.g., Lophosteus, Andreolepis, Psarolepis and Guiyu) retained part of the primitive gnathostome pectoral girdle condition with spines and/or other dermal components. However, very little is known about the condition of the pelvic girdle in the earliest osteichthyans. Living osteichthyans, like chondrichthyans (cartilaginous fishes), have exclusively endoskeletal pelvic girdles, while dermal pelvic girdle components (plates and/or spines) have so far been found only in some extinct placoderms and acanthodians. Consequently, whether the pectoral and pelvic girdles are primitively similar in osteichthyans cannot be adequately evaluated, and phylogeny-based inferences regarding the primitive pelvic girdle condition in osteichthyans cannot be tested against available fossil evidence.

Methodology/Principal Findings

Here we report the first discovery of spine-bearing dermal pelvic girdles in early osteichthyans, based on a new articulated specimen of Guiyu oneiros from the Late Ludlow (Silurian) Kuanti Formation, Yunnan, as well as a re-examination of the previously described holotype. We also describe disarticulated pelvic girdles of Psarolepis romeri from the Lochkovian (Early Devonian) Xitun Formation, Yunnan, which resemble the previously reported pectoral girdles in having integrated dermal and endoskeletal components with polybasal fin articulation.

Conclusions/Significance

The new findings reveal hitherto unknown similarity in pectoral and pelvic girdles among early osteichthyans, and provide critical information for studying the evolution of pelvic girdles in osteichthyans and other gnathostomes.  相似文献   

16.
A new anthine fish, Pseudanthias calloura, is described on the basis of three specimens from Palau. The new species differs from other congeners in having a complicated color pattern of the caudal fin and the following characters: moderately forked caudal fin; dorsal fin with 10 spines, the anterior ones being shorter than the rest, and with 16 soft rays; second anal spine shorter than the third; 19 pectoral rays; scales on lateral line 51 (holotype) to 53 (paratypes) in number; tongue without teeth; circumorbital rim with several fleshy projection on posterior part; a row of fine scales occurring asymmetrically behind alternate dorsal spines on both left and right sides; preopercle margin finely serrated; interopercle and subopercle margins smooth. Received: June 9, 1999 / Revised: September 23, 2000 / Accepted: February 23, 2001  相似文献   

17.
Some fishes use modified body structures – including pelvic fins – to produce suction to facilitate stability in turbulent environments. This study compares the morphology and osteology of the pelvic suckers of representative lumpfishes (Cyclopteridae), snailfishes (Liparidae) and gobies (Gobiidae). In all species studied the midline sucker (pelvic suctorial organ [PSO]) is formed from the pelvic girdle and fin rays I and 5 of the pelvic fins, comprised of similar osteological elements to those found in the pelvic girdle and pelvic fin rays although the morphology of the bony elements is species‐specific. Pelvic suctorial organs in those fishes that lack pelvic girdles are therefore homologous to pelvic girdles. The phenotypic diversity seen in so few species indicates that many sucker morphologies have arisen, origination depending on the concerted development of muscular, skeletal, nervous, and skin body tissues. The structure of the soft rays of the pelvic fins in the liparids and cyclopterids is unusual and indicative of unconventional developmental patterning of fin ray halves and of evolution in the underlying mechanisms responsible for the development of midline suckers.  相似文献   

18.
Gerres chrysops, a new gerreid species from the Gulf of Thailand, is described on the basis of 29 specimens, 58–83 mm in standard length (SL). A small-sized species (less than 100 mm SL), it is characterized by a silvery-gold sheen on the head and trunk, vivid yellow or yellowish-hyaline fins in life, two supraneural bones (formula 0/0/2/) and dorsal fin rays usually IX, 10. The new species is similar toG. decacanthus (Bleeker, 1865) andG. setifer (Hamilton, 1822), which are redescribed. being similarly small valid gerreid species characterized by two supraneural bones. Together, the three species comprise “theGerres setifer complex.”Gerres chrysops differs from bothG. decacanthus andG. setifer in life and fresh colors, the body being silvery-gold with vivid yellow or yellowish dorsal, caudal, anal and pelvic fins, and yellowish-hyaline pectoral fins (vs. silver body with hyaline fins in the latter two species).Gerres setifer differs fromG. chrysops andG. decacanthus in having the last dorsal fin spine longer than the penultimate spine (vs. almost same length or shorter), usually ten dorsal fin spines and nine soft dorsal rays (vs. usually IX, 10), and 8 or 9 lower series gill rakers (vs. usually 7).Gerres decacanthus differs fromG. chrysops andG. setifer in having a shorter head, lesser body depth at the first anal fin spine base, lesser body width at the pectoral fin base, and shorter second dorsal and third anal fin spines. The new species is currently known only from Angsilla, near Bangsaen, and around Si Chang Island, northeastern Gulf of Thailand.Gerres decacanthus inhabits southern Chinese waters andG. setifer is currently known from the Bay of Bengal to the Andaman Sea.  相似文献   

19.
本文记述的曲靖始突鱼(Procondylolepis qujingensis gen.et sp.nov.)是近几年在云南曲靖早泥盆世地层中发现的有肢突胴甲鱼一原始类型。它和已知胴甲鱼(包括早泥盆世无肢突的和中、晚泥盆世有“盔”状肢突的)不同的最大特点是在其肩带与胸鳍相接的肩关节处有原始的肢突和简单的关节窝;胸鳍甲近端的关节区很小。它展现出胴甲鱼类这一高度特化、长期使人迷惑不解的肢突,在胴甲鱼演化史上发展变化的梗概,填补了肢突从无到有中间的缺环,使人了解到胸鳍的具体结构。文中主要根据肢突的有无和特化程度等,对胴甲鱼早期演化史作了初步探讨,将胴甲鱼分为无肢突超目(Abrachicondylia)和有肢突超目(Brachicondylia)两大部分。始突鱼则代表有肢突超目一早期成员。  相似文献   

20.
Alectrias mutsuensis sp. nov. is described on specimens collected from Mutsu Bay, Aomori Pref. This new species is rather deep dweller compared to other species of the genus, living on muddy bottoms, about 20 to 40 meters deep, and is diagnosed by the following characters: dermal crest on head reaching to occipital region; distance between end of dermal crest and dorsal fin origin less than eye diameter; end of anal fin separated from caudal fin; anterior dorsal spines before anal origin, slender and flexible; epaxial hypurals mostly fused into a single plate. A key to all nine species belonging to the subfamily Alectriinae is presented.  相似文献   

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