Evolution of test formation in the Diaspididae

利用扫描电子显微镜研究了盾蚧科昆虫内囊形成的演化。观察了19种鱼类气门孔和外阴盘孔的超微结构，以支持尾足附属器分类方案。并对4种贝壳蚧和1种木虱进行了比较研究。贝壳虫试验是由粉碎的蜡丝组成的，这些蜡丝与肛门分泌的物质混合在一起，就像混合水泥的骨料块一样。C.乌须贝的内部结构相似，但它有一种特殊的分泌器官，这种分泌器官在一个五角形的管中产生蜡丝。在这方面，双盾虫试验是独特的，它使用长的蜡丝，这些蜡丝被肛门的物质凝集在一起。这种方式，当与昆虫的运动相结合时，可以产生各种各样的测试。然而，在一种奇怪的双盾虫（Ulucoccus）中，测试只是一团蓬松的蜡丝，它们是圆柱形的，从双生孔型的导管中分泌出来。在盾蚧科的原始形态中，内囊是由扁平的蜡丝形成的，但在内囊形成时昆虫身体没有运动。高级形式在形成测试时进行运动，并且存在从轻微振荡到完全旋转的分级系列运动。这种进化趋势一定发生在不止一个谱系中，这表明它具有深刻的适应意义。与这种趋势不一致的是，孤立的Sclopetaspis属产生蜡管，并且不动，形成不规则形状的蜡管。它可能代表了该家族主要种群的一个旁支分支，也可能是在进化试验过程中尝试的许多实验中的一种逃避。

Evolution of test formation in the Diaspididae was studied by the use of a scanning electron microscope. The ultrastructure of spiracular and perivulvar disc pores was observed in 19 species in order to find support for a classificatory scheme based on pygidial appendages. Four conchaspidid species and 1 lerp-forming psyllid (Celtiaspis usubai) were also studied for making a comparison with diaspidid tests. Conchaspidid tests are composed of crushed wax filaments, which are mingled with a substance excreted from the anus just like pieces of aggregate mixed with cement to make concrete. The completed lerp of C. usubai shows a similar interior structure, but it has a peculiar type of secretory organ, which produces wax filaments in a pentagonal tube. In this respect, diaspidid tests are unique by the use of long wax filaments, which are agglutinated together by a substance from the anus. This manner, when combined with the insect's movement, may produce a wide variety of tests. In an odd diaspidid (Ulucoccus), however, the test is simply a fluffy mass of wax filaments, which are cylindrical and secreted from the ducts of the geminate-pore type. In primitive forms of the Diaspididae the test is formed by flattened wax filaments, but no movement of the insect body takes place at the formation of test. Advanced forms make a movement when forming the test, and there is a graded series of movement from a slight oscillation to a complete rotation. This trend of evolution must have occurred in more than one lineage, suggesting its deep adaptive significance. In disagreement with this trend, the isolated genus Sclopetaspis produces wax tubes and, being immobile, forms an irregularly shaped mass of them. It may represent a side branch off the main stocks of the family, and may be an escape out of many experiments attempted in the course of test evolution.