| Guizhou province is located in the center of karst area in southwest China,which has complete karst landform and abundant cave resources and cave biological resources.Cave-dewlling species of the subgenus Gymnaeta are one of the dominant biological groups in caves in Guizhou Province,showing varying degrees adaptability to the cave environment and extremely high regional endemism,so they are worthy of study and protection.However,study on the taxonomy of cavernicolous species of this subgenus has not been well understood,and therefore,this aspect will be explored in this study.We focused on the following research areas:(1)collection,identification,and description of species;(2)observation and comparative analysis of ultrastructural morphology of eggs of 3 cave species of the subgenus Gymnaeta;(3)analyzing evolution of the morphological structure to the cave environment and underlying mechanism;and(4)exploring distribution patterns based on the distribution data in China.The main results are as follows:一、TaxonomyThe morphological characteristics of 25 cave species of the subgenus Gymnaeta published in China were described,and the localities,literature and distribution of type specimens were recorded.Based on the investigation of more than 50 karst caves in Guizhou Province,more than 2000 specimens were collected,and 18 new species were discovered.A key to cave-dewlling species of this subgenus in China is given.18 new species were described,including T.(G.)lalinensis,T.(G.)zaoshuensis,T.(G.)shuangchaensis,T.(G.)tongrenensis,T.(G.)pentagonus,T.(G.)plumiopedellus,T.(G.)dentatus,T.(G.)aterus,T.(G.)lingulatus sp.nov.,T.(G.)multispinus sp.nov.,T.(G.)microtuberculatus sp.nov.,T.(G.)ovalius sp.nov.,T.(G.)conicus sp.nov.,T.(G.)sordidus sp.nov.,T.(G.)triangulus sp.nov.,T.(G.)rectangularis sp.nov.,T.(G.)nigerus sp.nov.,and T.(G.)semibifolius sp.nov..二、Eggs ultrastructure of three speciesScanning electron microscope was used to observe the egg ultrastructure of T.(G.)lalinensis,T.(G.)tongrenensis,and T.(G.)plumiopedellus.It was found that there were great differences in the surface structure of egg shell,which shown that the egg ultrastructure can be used as the basis for the classification of cave species of this subgenus.三、Comparative morphological studyThe 14 morphological characteristics of 43 cave species of the subgenus Gymnaeta were studied.Among them,4 morphologic structures were selected,including eyes,conicusl tubercles,pronotum,and hind tibia dorsally spines,and found that these structures showed a degeneration tendency to adapt cave environment.Considering the degree of adaptive evolution of morphological structure,the cave species of this subgenus was divided into two groups—typical cave species and atypical cave species.The typical cave species showed a series of adaptive evolution characteristics in the morphological structure,while the atypical cave species showed no obvious changes in the morphological structure.四、Geographic distribution patternsIn China,cave species of the subgenus Gymnaeta are mainly distributed in six provinces with well-developed karst landforms.Among them,Guizhou province has the highest species richness of cave species and typical cave species of this subgenus.By analyzing the geographical distribution of single species,it was found that the distribution range of cave species of this subgenus was very narrow,nearly 65% of the species were confined to a single cave,and the remaining 35% were inhabiting multiple caves,and these species inhabiting multiple caves were only distributed in small areas of corresponding provinces.Furthermore,most species of typical cave species inhabit only in a single cave,while 44% of atypical cave species inhabit in multiple caves.It can be seen that from atypical cave species to typical cave species,there is a trend from multiple caves to single cave. |
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