湘中西部小鲵属一新种--挂榜山小鲵(两栖纲:小鲵科)

在比较和研究小鲵属Hynobius物种后 ,确定湖南省祁阳县产小鲵为一新种 ,即挂榜山小鲵Hynobiusguabangshanensissp .nov .。新种与安吉小鲵H amjiensis近似 ,它们体型较大 ;有 13条肋沟 ;前后肢贴体相向时指趾重叠较多 ;掌、突明显 ,但又有明显区别 :1)新种比安吉小鲵稍小 ,全长 139 32mm± 9 5 0mm (n=9) ;2 )犁骨齿细且排列密 ,外枝 9- 11枚、内枝 2 5 - 2 7枚 ;3)尾较短 ,平均为头体长之 70 4 % (n =9) ;4 )卵袋较短 ,香蕉形弯曲等。本文列表比较近似种 ,统计并记述了新种     

挂榜山小鲵的繁殖生态

2004-2006年对挂榜山小鲵(Hynobius guabangshanensis)的繁殖生态进行了观察研究.结果表明:挂榜山小鲵繁殖期为每年的11月中旬至翌年1月;非繁殖期营陆生生活,繁殖期进入水中繁殖;繁殖期活动高峰为20:00到翌日6:00;繁殖种群数量为198条,现存分布区不足10 km2;繁殖期雌雄性比为1.6,存在明显的两性异型,性成熟雌体的体长和体质量显著大于雄体;挂榜山小鲵的抱对行为与东北小鲵、黑小鲵、极北鲵相似;雄体具有求偶炫耀行为和精子竞争行为;繁殖场多为临时水凼和小而浅的池塘,大部分卵袋被固定在浅水的枯枝和水草上;挂榜山小鲵的卵袋较同科物种粗大,幼体刚出膜时卵袋长(18.40±4.21) cm(n=31),直径(4.23±0.52) cm(n=31);卵径(2.10±0.25) mm(n=45);卵粒数(88.90±20.30)个(n=98)(单个卵袋),受精率为(93.3±21.4)%(n=98).     

中国小鲵的核型

中国小鲵(Hynobius chinensis)被描述于116年前,我国学者于2005年在模式产地湖北宜昌再次采到标本,至此该物种的有效性得以确认。以2007年采于模式产地的中国小鲵胚胎为材料,采用Giemsa染色方法,对中国小鲵的核型进行了分析。结果表明,中国小鲵的二倍体染色体数为56,28对染色体按大小和形状可以分为4组:第一组,包括Nos.1～9,由大型m,sm,st染色体组成;第二组为中型双臂染色体组,由Nos.10～13组成,包含m,sm染色体;第三组,包括Nos.14～18,由小型m染色体组成;第四组,包括Nos.19～28,由小型t染色体组成。与小鲵属其他物种相比,中国小鲵核型与具染色体数为2n=56的类群核型大致相同,差异出现在染色体分组和相应染色体着丝点类型上。     

挂榜山小鲵精子形态结构研究

应用扫描电镜和透射电镜对挂榜山小鲵(Hynobius guabangshanensis)精子的超微结构进行观察和研究.结果表明:1)挂榜山小鲵的精子形态具有小鲵科精子的共同特征:头部细直、有锥形顶体;颈部短而不明显,尾部细长、有波动膜;2)该种小鲵的精子超微结构具小鲵科物种精子的共同特征,即精子无顶体钩,顶体呈三叶草状,尾部无线粒体,轴纤维粗大呈圆柱状等;3)除精子全长(194.1±7.15μm)在小鲵科物种中属于中等外,挂榜山小鲵和本科其他物种的精子在形态量度学方面差异明显:其头部占全长的比例(22.98%)比其他已知小鲵科的物种都低,尾部占全长的比例(65.79%)比其他小鲵科物种都高.     

挂榜山小鲵早期胚胎发育初步观察

2005年1～2月,在Nikon体视镜下对挂榜山小鲵的早期胚胎发育过程进行了观察,对不同发育时期进行了数码拍照。根据胚胎发育的外部形态及典型特征将挂榜山小鲵早期胚胎发育过程分为21个时期。在水温6．5～10℃的条件下,受精卵历时1134h孵化出膜,初孵幼鲵全长约16．50mm。     

挂榜山小鲵线粒体DNA COⅠ基因及D-loop区序列研究

研究克隆了挂榜山小鲵COⅠ基因及D-loop区全长,结果显示挂榜山小鲵COⅠ基因及D-loop区全长分别为1 551 bp和803 bp.运用MEGA4.0软件P-distance法分别比较COⅠ基因及D-loop区小鲵科19个物种的遗传距离,结果显示挂榜山小鲵与小鲵属遗传距离比与小鲵科其它属物种的小,并且挂榜山小鲵与Zhang et al(2006)提交的中国小鲵相应序列的遗传距离几乎为0,构建了MP分子系统发生树也显示挂榜山小鲵与小鲵属同属一个分支,且与Zhang et al提交的中国小鲵聚为一小支.通过以上分析认为挂榜山小鲵属于小鲵科小鲵属,这与传统分类学方法一致.     

三种小鲵和极北鲵的核型

本文报道了安吉小鲵（Ｈｙｎｏｂｉｕｓａｍｊｉｅｎｓｉｓ）、中国小鲵（Ｈ．ｃｈｉｎｅｎｓｉｓ）、东北小鲵（Ｈ．ｌｅｅｃｈｉ）（辽宁桓仁）和极北鲵（Ｓａｌａｍａｎｄｒｅｌａｋｅｙｓｅｒｌｉｎｇｉ）（吉林白河）的核型。３种小鲵２ｎ＝５６,染色体按大小和形状分为大、中、小型双臂和小型单臂４组。极北鲵２ｎ＝６２,染色体按大小和形状可分为大、中、小型３组。对东北小鲵辽宁桓仁与辽宁千山标本核型的显著差异结合分类学问题进行了讨论。对３种小鲵核型进行了比较分析,并讨论了中国的小鲵属核型特点。比较了不同地区极北鲵核型的异同,并将其与小鲵属核型进行了比较。     

千山产东北小鲵的染色体组型

本文报道取材两栖类胚体细胞和成体肠细胞的方法进行染色体研究。对千山产东北小鲵的染色体组型分析表明,其二倍体染色体数目为2n=54。全部染色体可配成27对,分或三组。其中有9对大型染色体,7对中型染色体,11对小型染色体,未发现有异型性染色体存在。染色体的形态有中部,亚中部、端部,亚端部着丝点染色体。     

中国小鲵属一新种(两栖纲:有尾目:小鲵科)

对采自我国河南省商城的一种小鲵标本进行了研究,认为与我国产小鲵科巳知属、种及日本产小鲵属相近种均不相同,被确定为新种,即豫南小鲵Hynobius yunanicus sp.nov.。     

拟小鲵属(有尾目:小鲵科)一新种--水城拟小鲵

在比较和研究拟小鲵属(Pseudohynobius)已知二物种后,确定贵州省水城县石龙乡产拟小鲵为一新种,即水城拟小鲵(PseudohynobiusshuichengensisTian,LietGusp.nov)。新种与黄斑拟小鲵(P.flavomaculatus)的犁骨齿列形状相似;但新种体尾及四肢背面紫褐色,无黄色斑块;四肢长,前后肢贴体相向时,掌、部前半重叠;而黄斑拟小鲵体尾及四肢背面紫褐色,有土黄色斑块;四肢甚短,前后肢贴体相向时,指、趾仅相遇或略重叠。秦巴拟小鲵(P.tsinpaensis)背面棕褐色,体尾及四肢背面有不规则云状斑;四肢较短,前后肢贴体相向时,指、趾末端仅相遇。本文统计并记述了新种的外形、头骨特征、生物学资料。     

Karyotype of a Japanese salamander Hynobius katoi and its implication on breeding ecology (Amphibia: Caudata)

Karyotype of a Japanese small salamander, Hynobius katoi, was first described. All individuals examined had 2n=58 chromosomes, consisting of nine pairs of biarmed macrochromosomes, four pairs of biarmed medium-sized chromosomes, six pairs of biarmed microchromosomes, and 10 pairs of uniarmed microchromosomes, although distinction of the second and the third groups of chromosome pairs was not clear. All pairs appeared homologous and no sexual dimorphism was found. Possession of 2n=58 chromosomes in H. katoi strongly suggests its lotic-breeding habits as was expected from the number and size of eggs and adult morphology. When compared morphology of chromosomes among lotic-breeders with 2n=58 chromosomes, metacentric nature of No. 10 seems to characterize the karyotype of H. katoi.     

Karyotypes of two rare species of hynobiid salamanders from Taiwan,Hynobius sonani (Maki) and Hynobius formosanus Maki (Urodela)

Two salamanders endemic to Taiwan, Hynobius sonani and Hynobius formosanus, are similar to Japanese hynobiids in having 2n = 58 chromosomes and by the absence of a medium-sized telocentric pair. H. sonani has 6 metacentric and 10 telocentric microchromosome pairs, while H. formosanus has 5 metacentric and 11 telocentric microchromosome pairs. The karyotype of H. sonani is nearly identical to that of the Japanese hynobiid salamander H. boulengeri. Karyophylogenetic relationships among forms of mountain-stream type hynobiids of Taiwan and Japan are discussed.This paper is dedicated to late Mr. Tadao Yamamoto who died on November 2, 1985.     

Cytogenetic studies of Hynobiidae (Urodela)XVIII. A ZZ/ZW sex-determining mechanism in a hynobiid salamander species,Hynobius tokyoensis Tago

The karyotype of Hynobius tokyoensis (2n = 56) was analyzed using three kinds of banding methods to determine the morphological differentiation of the sex chromosomes of this species. Salamanders and egg sacs were collected from seven localities around Tokyo, Japan. Of 28 chromosome pairs, microchromosome No. 21 was identified as a ZZ/ZW-type sex chromosome. The Z chromosome was acrocentric, whereas the W chromosome was submetacentric, with a heterochromatic, elongated short arm. Interestingly, the W chromosome is of three distinct types, W(A), W(B), and W(C), based on R-banding and Ag-NOR patterns. W(A) was detected in five populations from southern habitats, whereas W(B) and W(C) were detected in one population each from northern habitats. W(A), W(B), and W(C) were all found to carry Ag-NORs on their heterochromatic short arms. Considering the karyotypes of other species belonging to the same genus, we discuss the evolution of the sex chromosomes of H. tokyoensis.     

Chromosomal description of the rodent generaOecomys andNectomys from Brazil

We analysed karyotypes of five taxa of the rodent generaOecomys andNectomys, trapped in 14 localities in an area ranging from 8° to 29°S on Brazilian territory.Oecomys cf.concolor, collected in the Amazon and in two localities of the Cerrado biome, showed a 2n=60 karyotype constituted by a pair of large subtelocentric chromosomes, a small metacentric pair and 27 acrocentric pairs. The X chromosome was a large submetacentric and a subtelo-submetacentric, the morphology of the latter showing variable C-banding patterns. In all three localities the Y chromosome was a medium size heterochromatic acrocentric. Two individuals from the Cerrado had a heterochromatic acrocentric B-chromosome.Oecomys cf.bicolor presented two cytotypes, 2n=80 in the specimens from the Cerrado biome and 2n=82 in individuals trapped in the Amazon. The 2n=80 cytotype 1 showed a large subtelocentric, 22 biarmed pairs (medium to small) and 16 acrocentric autosomal pairs. The karyotype of the 2n=82 cytotype 2 is constituted by 15 biarmed chromosomes (median to small) and 25 acrocentric pairs with heterochromatic blocks at pericentromeric regions. The sexual pairs were the same (large submetacentric X and median acrocentric Y) in both cytotypes. InO. cf.concolor and in both cytotypes ofO. cf.bicolor the nucleolar organizer regions were observed in 1-3 pairs, located in the short arms.Nectomys genus presented two cytotypes, 2n=52–55 (N. rattus, with 0–3 biarmed heterochromatic accessory chromosomes) and 2n=56–59 (N. squamipes, bearing 0–3 biarmed, heterochromatic, B-chromosomes). These 2 cytotypes occupy disjunct regions of South America, with overlapping areas in the Brazilian states of Pernambuco, Bahia, and Mato Grosso do Sul.     

挂榜山小鲵成体和亚成体舌器的形态特征

以透明骨骼双色法对挂榜山小鲵(Hynobius guabangshanensis)成体和亚成体舌器的形态特征进行观察和详细描述。结果表明,在成体中,下舌软骨中部交叉;角舌软骨末端被第一下鳃骨和第一角鳃骨的愈合体遮盖;具有基鳃软骨角状突;第二角鳃骨骨化;尾舌骨骨化,呈"一"字形。在亚成体中,下舌软骨中部未交叉;第一下鳃骨和第一角鳃骨单独存在;无基鳃软骨角状突;第二角鳃骨未骨化;具有第三、第四对角鳃骨,且均为软骨;尾舌骨未骨化,成"1"字形。这些形态特征的改变可能由舌器在成体和亚成体阶段的功能所引起。     

A new karyotype in Callicebus torquatus (Cebidae, Primates)

We describe a new karyotype of Callicebus torquatus using conventional staining, G-banding with Wright Stain, CBG, Ag-NOR staining and fluorescence in situ hybridization (FISH) with human telomere probes and comparative analysis with the previously reported karyotype of C. torquatus torquatus (2n = 20). We studied a female specimen maintained in captivity at the Centro Nacional de Primatas (Para, Brazil). This titi monkey presented 2n = 22, with four large biarmed and six acrocentric autosome pairs; the X chromosome is a medium submetacentric. C-bands were revealed at the centromeric region of all acrocentrics and X chromosome; punctual C-bands also are visualized at the centromeric region in the large biarmed pairs. The NOR site was located at the long arm of pair 4, at the position of a conspicuous secondary constriction. Hybridization signals were detected exclusively at the terminal region of all chromosomes. The karyotype described here has one acrocentric pair more than that found in the literature and also differs by amount and distribution of constitutive heterochromatin. Our data support the notion that the torquatus group may be composed of distinct species, each with its own karyotype.     

Polymorphism of the Sphaerium corneum (Bivalvia, Veneroida, Sphaeriidae) revealed by cytogenetic and sequence comparison

Two populations of Sphaerium corneum were sampled from River Vilnelė and small pond in Vilnius, Lithuania. The chromosomes were studied using conventional Giemsa staining and karyometric analysis. Inter- and intra-individual variation in the diploid chromosome numbers was revealed and two different sources of chromosome variability were identified: B chromosomes and the structural changes of chromosomes of the basic (A) set. The chromosome set of the more common karyotypic form, 2 n  = 30, found in both populations, consists of all biarmed metacentric and meta-submetacentric chromosomes of gradually decreasing size. Small, biarmed, mitotically unstable B chromosomes were found in the cells of this karyotypic form. Specimens with 2 n  = 36 were found only in pond. No B chromosomes were detected in their cells. The karyotype is characterized by presence of two pairs of medium telocentrics and four pairs of small subtelocentrics. The remaining chromosomes are biarmed. Robertsonian fusions appear to be involved in formation of two karyotypic forms of S. corneum . DNA sequence analyses showed that ITS1 is identical in both karyotypic forms. On the other hand, differences in 16S sequence were revealed and two haplotypes, corresponding to two karyotypic forms, were identified. The present study opens new perspectives in establishing species-specific characters for confident identification of Sphaerium species and provides insights to the genetic intraspecific variability and possible mechanisms of speciation.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 89 , 53–64.