Taxonomy and Phylogeny of Dicyemid Mesozoans

双网中生动物的分类学和系统发育

基本信息

批准号：
14540645
负责人：
FURUYA Hidetaka
金额：
$ 2.11万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2005
项目状态：
已结题

项目摘要

(1) Description of new species of dicyemids.Ten new species of dicyemids were described from Sepioteuthis lessoniana, Sepia latimanus, Amphictopus areolatus, A.kagoshimensis, and A.fangsiao in Japanese seas.(2) Phylogenetic and evolutionary studies on dicyemidsThe calotte morphology of dicyemids appears to result from adaptation to the structure of host renal tissues and help to facilitate niche separation of coexisting species.In most dicyemids distinctly small numbers of sperms are produced in a hermaphroditic gonad (infusorigen). The number of eggs and sperms are roughly equal. All inverse proportional relationship exists between the number of infusorigens and that of gametes, suggesting a trade-off between them.The renal organs of 32 species of cephalopods were examined for parasite fauna and for histological comparison. Two phylogenetically distant organisms, dicyemid mesozoans and chromidinid ciliates, were found in 20 cephalopod species. Most benthic cephalopods (octopus and cut … More tlefish) were infected with dicyemids. Dicyemids and chromidinids attach their heads to epithelia or insert their heads into folds of renal appendages, pancreatic appendages, and branchial heart appendages. The rugged and convoluted external surface provides a foothold for dicyemids and chromidinids with a conical head. They apparently do not harm these tissues of their host cephalopods.Cell numbers and cellular composition were examined in infusoriform larvae of 44 species of dicyemid mesozoans belonging to 6 genera ; Conocyema, Dicyema, Dicyemennea, Dicyemodeca, Mocrocyema, and Pseudicyema. Infusoriform larvae consist of a constant cell number which is species-specific. Small interspecific variations are found in total cell numbers, 35, 37, 39, 41, and 42. Most differences in total cell numbers are due to the absence or presence of particular ventral cells. In all infusoriform larvae, the lateral, dorsal and caudal areas are cell constant, whereas in the apical and ventral areas a distinct and variablc configuration of cells are present. Less

(1)双线虫新种描述。从日本海域的乌贼属、大乌贼、Amphictopus areolatus、A.kagoshimensis和A.fangsiao中描述了10个双线虫新种。(2)双线虫的系统发育和进化研究双酶胺的形成似乎是由于适应宿主肾组织的结构而产生的，有助于促进生态位分离在大多数双细胞动物中，雌雄同体的性腺（infusorigen）中产生的精子数量明显较少。卵子和精子的数量大致相等，infusorigen 的数量与配子的数量之间存在反比关系，这表明存在交换。对 32 种头足类动物的肾脏器官进行了寄生虫动物群检查，并对两种系统发育较远的生物体进行了组织学比较。在 20 种头足类动物（章鱼和切鱼）中发现了双环目中生动物和双环纤毛虫，它们的头附着在上皮上或将头插入肾附属器、胰附属器的褶皱中。和鳃心附属器崎岖而复杂的外表面为它们提供了立足点。具有圆锥形头部的二细胞目和染色素显然不会伤害其宿主头足类动物的这些组织。对属于 6 个属的 44 种双细胞目中生动物的细胞数量和细胞组成进行了检查；Conocyema、Dicyema、Dicyemodeca、Mocrocyema和假丝虫状幼虫由总细胞数有 35、37、39、41 和 42 个恒定的细胞数。总细胞数的大多数差异是由于特定腹侧细胞的存在或不存在造成的。纤毛状幼虫的侧面、背侧和尾侧区域的细胞是恒定的，而在顶端和腹侧区域存在明显且可变的细胞结构。