Michalik Peter, Sacher Peter, Alberti Gerd
Zoologisches Institut and Museum, Ernst-Moritz-Arndt-Universität, D-17489 Greifswald, Germany.
J Morphol. 2006 Feb;267(2):129-51. doi: 10.1002/jmor.10226.
The present study reports on the ultrastructure of spermatozoa and spermatogenesis of 12 tetragnathid spiders (10 Tetragnatha species [T. boydi, T. dearmata, T. extensa, T. montana, T. nigrita, T. obtusa, T. pinicola, T. reimoseri, T. shoshone, T. striata]; Pachygnatha listeri and Metellina segmentata). All species develop typical cleistospermia with a coiled nucleus in the center and a coiled axoneme in the periphery of the cell. Remarkable differences in the sperm ultrastructure of the investigated species comprise the shape of the main sperm cell components (nucleus, acrosomal complex, implantation fossa, and centriolar complex). Within the observed Tetragnatha species, three types of sperms were characterized: T. montana-type, T. boydi-type, and T. striata-type. The highly derivative T. montana-type is characterized by the following remarkable features: an extremely elongated nucleus, shaped like a corkscrew and twisted around the axoneme (before coiling); a deep implantation fossa; a corkscrew-shaped acrosomal vacuole; after the coiling process, the nucleus is coiled five to six times in the center of the spermatozoon and the axoneme is coiled five to six times peripheral to the nucleus. The T. boydi-type hardly differs from the T. montana-type, but is remarkable due to the triangular-shaped nucleus (in cross section). The T. striata-type differs especially by a peculiar acrosomal vacuole with a long, slightly curved process and a short appendix, as well as a nucleus that describes only three loose coils around the axoneme (before coiling). The spermatozoa of Pachygnatha listeri and especially Metellina segmentata differ strikingly from the described Tetragnatha-types and are similar to more primitive araneomorph spermatozoa, such as Hypochilus pococki. The described Tetragnatha-types completely correspond with Okuma's (1988a,b, J Fac Agr Kyushu U 32:165-181, 32:183-213) classification of Tetragnatha species. Furthermore, our results suggest an early derivative systematic position of Pachygnatha within Tetragnathinae and the position of Metellina within the Tetragnathidae.
本研究报告了12种园蛛科蜘蛛（10种长脚蛛属物种[T. boydi、T. dearmata、T. extensa、T. montana、T. nigrita、T. obtusa、T. pinicola、T. reimoseri、T. shoshone、T. striata]；李氏肥腹蛛和分节梅塔蛛）精子的超微结构和精子发生过程。所有物种均发育出典型的闭管式精子，细胞核盘绕在细胞中央，轴丝盘绕在细胞周边。所研究物种精子超微结构的显著差异包括主要精子细胞成分（细胞核、顶体复合体、植入窝和中心粒复合体）的形状。在所观察的长脚蛛属物种中，鉴定出三种类型的精子：蒙大拿长脚蛛型、博伊德长脚蛛型和条纹长脚蛛型。高度特化的蒙大拿长脚蛛型具有以下显著特征：细胞核极度细长，呈螺旋状，在轴丝周围扭曲（盘绕前）；植入窝深；顶体泡呈螺旋状；盘绕过程后，细胞核在精子中央盘绕五到六次，轴丝在细胞核周边盘绕五到六次。博伊德长脚蛛型与蒙大拿长脚蛛型几乎没有差异，但因其细胞核呈三角形（横截面）而显著。条纹长脚蛛型的特别之处在于其独特的顶体泡，有一个长的、略弯曲的突起和一个短的附属物，以及一个在轴丝周围仅盘绕三个松散螺旋的细胞核（盘绕前）。李氏肥腹蛛尤其是分节梅塔蛛的精子与所描述的长脚蛛属类型显著不同，与更原始的新蛛亚目精子相似，如波氏低眼蛛。所描述的长脚蛛属类型与奥库马（1988a、b，《九州大学农学部纪要》32:165 - 181，32:183 - 213）对长脚蛛属物种进行的分类完全相符。此外，我们的结果表明肥腹蛛在园蛛亚科内处于早期分化的系统位置，而梅塔蛛在园蛛科内的位置也是如此。
