| The family Pseudococcidae belongs to Hemiptera, Coccoidea, approximately 2017 species belonging to 268 genera are known in the world, which are distributed in all zoogeographic regions. All the Mealybugs are phytophagous insects, which can adapt to all kinds of environment. Mealybugs infect the plants of agriculture, fruit, gardens, forest and pasture, and cause serious economic losses. This requires that we continue to strengthen prevention and control work of the Mealybugs, however, classification of Pseudococcidae is the basis of all studies. Therefore, the taxonomic study to Pseudococcidae is indispensable.In the present study of the Pseudococcidae, identification of mealybugs relies mainly on the morphological characters of the adult female, only the immature stages of 104 mealybug species in 56 genera are studied by previous workers. However, most studies are restricted to descript single or a few species, it is not enough to form a complete system. Hence, there is an urgent need for more detailed descriptions with illustrations of the immature mealybugs.This paper begins with an overview of the historical and current studies on immature mealybugs, and introduces the materials and methods, then elaborates the results of research and analysis in two parts including classification of first-instar nymphs of Pseudococcidae and the phylogeny based on their morphological characteristics.In the part of taxonomy, first-instar nymphs of 13 species of Pseudococcidae are described in detail with 13 illustrations, and some ecological photos are provided; a key is provided to species of Pseudococcidae based on the morphology of first-instar nymphs from China. Amounting to 13 species belonging to 11 genera first-instar nymphs are recorded in our study. Among them,8 species are described and illustrated for the first time, including the first-instar nymph of one new species; 5 species are redescribed and re-illustrated.Firstly described and illustrated species:Antonina tesquorum Danzig, Coccura suwakoensis Kuwana et Toyoda, Crisicoccus sp., Dysmicoccus angustus Ezzat & McConnell, Heliococcus dorsiporosus Danzig, Phenacoccus solani Ferris, Planococcus minor Maskell, Planococcus kraunhiae Kuwana。The redescribed and re-illustrated species:Maconellicoccus hirsutus Green, Nesticoccus sinensis Tang, Nipaecoccus viridis Newstead, Planococcus citri Risso, Sinococcus ulmi Wu & Zheng.In the part of phylogeny, the mealybug phylogenies are constructed using Bayesian inference methods with MRBAYES 3.1.2,22 morphological characters are selected, and the species Puto kosztarabi Miller & Miller of Putoidae is used as outgroup. The results reveal that the phylogenetic tree can’t explain the mealybug phylogeny successfully, we can only get the following conclusions:the genera Phenacoccus Cockerell and Pseudococcus Westwood are non-monophyletic groups. Macrocepicoccus loranthi Morrison is a sister group of Leptococcus eugeniae Miller & Denno, form a clade. The genus Antonina Signoret much closes to Chaetococcus Maskell, but further sdudies of phylogenetic relationships among species of the two genera are needed. The genus Brevennia Goux has been regarded as related to Heterococcus Ferris, and it is proved by the mealybug phylogeny based on morphological characters of first-instar nymphs.All specimens studied are deposited in the Insect Collection, the Department of Forestry Protection, Beijing Forestry University, Beijing, China (BFUC). |
