论水螨腺毛形态学与螨类体躯进化(蜱螨亚纲:水螨群)

ON GLANDULARIA MORPHOLOGY OF WATER MITES (ACARI, ACTINEDIDA, HYDRACHNELLAE) AND EVOLUTIONARY THEORY OF THE MITE SOMA

基于对中国水螨区系120余种的研究和有关文献，本文提出了水螨腺毛分布体位的原始模式；据腺毛腺体及围腺片等结构特征，将水螨腺毛分为四个结构类型：皱喙螨型、盾水螨型、水螨型和腺水螨型；腺毛结构特征表明，其发生与起源和体躯形态进化相关；全面评述了节肢动物和螨类体躯及体节进化的现有理论、分析讨论了关于螨类祖先体躯模式的Grandjean－Coineau氏学说（十六节说）和Bader氏学说（十二节说），由此并结合作者研究提出了螨类（水螨），原始祖先体躯模式的新假说（十八节说）。

The essential distribution model of 18 pairs of hydrachnelles' glandularia, including 2 pairs of antennal glandularia (A1, A2), 4 pairs of dorsoglandularia (D1 ~D4), 4 pairs of lateroglandularia (L1 ~L4 ), 4 pairs of epimeroglandularia (E1 ~E4 ), and 4 pairs of venteroglandularia (V1 ~V4), and 2 pairs of non-glandularia seta named ocularia (O1, O2)is defined through comparative studies on more than 120 Chinese species of water mites. It is considered as a primitive distribution scheme from whice the patterns of the glandularia for different families of water mites can be drawn.According to the structural features of the glandularial glands and sclerites, the glandularia are grouped into four distincti types, eylaoides type - the most prirnitive one,hydryphantoides type, hydrachnoides type and lebertioides type. The lebertioides type is present in three higher groups including Lebertioidea, Hygrobatoidea and Arrenuroidea, and is considered to be recent in the evolutionary scale.A new hypothesis, 'eighteen-segment theory,' of the origin of the mite descending from worm-like ancestor with 18 segments (Ⅰ~ ⅩⅧ ) and a precheliceral lobe (pl), is proposed through a careful study of the glandularia. The gland structure of hydrachnelles' glandularia shows no similarity to other glandular structures or organs found in all acarides groups. This means that the 18 pairs of glandularia independently derived from 18 intersegmental folds between primary segments of the worm-like ancestor in the course of evolution of soma with reducing body axis. The 'eighteen-segment theory' presumes that the transferring of the ancestor's segments, to reduce body axis, is directed by two stable points,'das 1' between Ⅳ and Ⅴ and 'das 2' at area of genital pore. Toward 'das 1' and 'das 2', Ⅰ, Ⅱ and pl transfer dorsally and over Ⅲ and Ⅳ, Ⅶ ~Ⅹ dorso-anteriorly and over Ⅴand Ⅵ, ⅩⅤ ~ ⅩⅧ ventrally and behind the genital pore. The impressive explanation of the theory is given with the terms used by Grandjean. Other theories, 'sixteen-segment theory' by Grand jean in 1969 and Coineau in 1972 and 'twelve-segment theory' by Bader in 1982, and phylogenetic points of view on arthropod groups are discussed in detail.