Comparative Morphology And Phylogenetic Analysis Of Chinese Soil Darkling Beetles Based On The Characteristics Of Defensive Glands

The soil darkling beetles comprise approximately 40% of the total Tenebrionidae. In addition to a few diurnal species, mostly are nocturnal species. The former often have not defensive glands, while the latter usually have well-developed defensive glands, which can defense the insects against predators, protect habitat and gather the population by releasing secretions. The shapes of the glands are significant different between different groups, so that can be used to distinguish species and deduce high-level phylogenetic relationships. So it arose the concern of academic community for long time. Based on large number of anatomised representative specimens and morphological comparison, this dissertation summarized evolutionary process and trends of defensive glands of the Chinese soil darkling beetles. Main achievements obtained as followings:We studied on reservoir's features of 16 tribes 41 genera 98 species of the soil darkling beetles. Using its shape, length, width, the distance between the two glands, and gland surface decorated whorles and wrinkles as classification standards, we described the morphological characters in standard form. Identification keys are given and various kinds of picture of defensive glands are provided. Our research confirmed that defensive glands have very great morphological changes beyond the level of genus and these changes have important taxonomic value. It can be used for species identification and taxonomic status determination, with wide range of research value.The morphological diversity of defensive glands accompanied by the diversity of group differentiation in soil darkling beetles, and the two have high degree of consistency. In the more evolutional Blaptini and Platyscelidini, there have more obvious differentiation between genera. While the differences are less obvious between genera in the more original Opatrini, and the boundaries of genera level are not clear. Accordingly, it can be used to predict the phylogenetic relationships of the soil darkling beetles.We speculated the tribe-level evolutionary trends of the Chinese soil darkling beetles. Based on the data from comparative morphology, using systematic classification software, we initial established the phylogenetic relationship of the 8 tribes. The result shows the evolutionary trends should be as follows: Tenebrionini, Crypticini>Triboliini>Opatrini>Pedinini>Lupropini>Platyscelidini>Blaptini.Through comprehensive analysis of existing data, we can speculate that the defensive glands of the soil darkling beetles have experienced a long evolutionary process, from lower to higher, from simple to complex. No matter how much morphological changes of defensive gland, it all have a clear common origin (homology), differentiation development (glands polymorphism) and the phased development (unlike groups have different characteristics and defensive behavior) in nature. We Inferred evolutionary process of defensive glands: no glands>have defensive glands>single gland>evert>a pair of glands>spray. Defensive glands have undergone many changes in it's long evolutionary history, such as the reservoirs'location move forward, the volume of reservoirs and fluid volume increased gradually, the wall gradually thicken and is suitable for injection.