Taxonomy and Phylogeny of Dicyemid Mesozoans

(1)本文记述了产于日本海域的雷氏乌贼（Sepioteuthis lessoniana）、宽手乌贼（Sepia latimanus）、方斑双鳍乌贼（Amphictopus areolatus）、鹿儿岛双鳍乌贼（A.kagoshimensis）和方小双鳍乌贼（A.fangsiao）的10个新种。(2)双孢子虫的系统发育和进化研究双孢子虫的冠状形态似乎是适应宿主肾组织结构的结果，有助于促进共存物种的生态位分离。卵子和精子的数量大致相等。在32种头足类动物肾器官中，寄生虫的数量与配子的数量成反比关系，表明它们之间存在着一种平衡关系。在20种头足类动物中发现了两种远缘生物，即双孢子类中生动物和染色质类纤毛虫。大多数底栖头足类动物（章鱼和切割） ...更多信息 tlefish）感染了dicyemids。双孢子虫和染色虫将它们的头附着在上皮细胞上，或者将它们的头插入肾附属器、胰腺附属器和鳃心附属器的褶皱中。粗糙和回旋的外表面提供了一个立足点，为dicyemids和chromidinids与圆锥形的头部。它们显然不伤害这些组织的宿主cephalopods.Cell数量和细胞组成的44种dicyemid中的纤毛虫幼虫，属于6属; Conocyema，Dicyema，Dicyemennea，Dicyemodeca，Mocrocyema，和Pseudicyema检查。虫形幼虫由恒定的细胞数量组成，这是种特异性的。小种间变异被发现在总细胞数，35，37，39，41，和42。细胞总数的差异主要是由于特定腹侧细胞的存在或缺失。在所有的纺锤形幼虫中，外侧、背侧和尾侧区域的细胞是恒定的，而在顶侧和腹侧区域的细胞是不同的和可变的配置。少

(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