17种陆生贝类齿舌的扫描电镜观察及分类学意义探讨

Observation on Radulae of 17 Species of Terrestrial Mollusks by Scanning Electron Microscopy and Its Taxonomic Significance

采用扫描电镜观察了3目10科12属17种陆生贝类的齿舌形态。结果显示,17种陆生贝类齿舌的中央齿均为1列,侧齿12~218列不等,缘齿0~204列不等。中央齿依齿片上小齿数目分为单齿型、三齿型和多齿型:侧齿与缘齿的形态多样,侧齿齿片上小齿数1~6枚不等,缘齿齿片上小齿数1~10枚不等。结合以往报道的38种陆生贝类齿舌,对3目20科41属共55种齿舌形态进行了比较分析。结果显示,陆生贝类齿舌的中央齿、侧齿和缘齿的形态以及小齿数目在不同科之间差异较大,相同属则差异较小。同一科中不同种齿舌列数不尽相同且没有规律。齿舌形态特征在不同分类阶元上具有分类学意义。

[Objectives]The radula of the terrestrial mollusk is generally composed of a central vertical tooth row,several vertical rows of lateral teeth on both sides,and several vertical rows of marginal teeth on both sides of the lateral teeth.The aim of the present study was to analyze the radulae characteristics of different families,genera,species of terrestrial mollusks,and to further explore the taxonomic significance of radula form classification hierarchies of terrestrial mollusks.[Methods]With the back of the terrestrial mollusk facing upwards,the mantles on both sides were separated,the buccal mass was taken,and the muscle tissue was removed toobserve the radula sac.The radula sac was treated with 5%NaOH solution for 3 to 5 minutes,followed by peeling off the radula and removing the connective tissue,then the alkaline solution on the radula was wash off with distilled water,followed by ultrasonic cleaning.After dehydration with alcohol gradients,samples were stored in 70%alcohol.The radulae were transferred to the sample table for metal spraying after natural drying,and were observed and photographed under the FEI Quanta 200F scanning electron microscope(SEM).The radulae of 17 species of terrestrial mollusks belonging to 3 orders,10 families,12 genera were observed.[Results]The results showed that among the 17 species of terrestrial mollusks studied,the number of vertical rows of central teeth was all one.The numbers of vertical rows of lateral teeth ranged from 12 to 218,and the numbers of marginal teeth ranged from 0 to 204.The central teeth were divided into unicuspid,tricuspid,and multitooth types(Fig.5).There were many types of lateral teeth and marginal teeth.The numbers of cusps of lateral teeth were from 1 to 6,and the numbers of cusps of the marginal teeth varied from 1 to 10.[Conclusion]Combined with the 38 species of terrestrial mollusks previously reported,there are 55 species in total in 3 orders,20 families,and 41 genera,and the morphology and numbers of cusps of the central teeth,lateral teeth,and marginal teeth of terrestrial mollusks of different families are quite different.Radulae of the same genus have similarities in morphology,and the difference in morphology is small.The numbers of vertical rows of different species in the same family are quite different,and there is no regularity(Appendix 2).The morphological characteristics of radula have important taxonomic significance in different classification hierarchies.