Mealybugs (Hemiptera: Pseudococcidae) are an insect group that feeds on plant sap; many are major pests of ornamental plants and crops worldwide. The difficulty of morphological identification of mealybugs points to a need for a rapid and effective identification method, like DNA barcoding, to assist morphological taxonomy. Here, we employed diverse methods (best close match [BCM], Neighbor-Joining [NJ] tree, Barcoding with LOGic formulas [BLOG], Poisson Tree Process [PTP] Species Delimitation Method) to test the efficiency of two molecular markers (mitochondrial cytochrome c oxidase I [COI] and large ribosomal subunit gene [28S]) that could be used for species identification of 54 mealybug species that commonly occur in China. Two hundred six COI barcodes (47 species) and 242 28S sequences (53 species) were recovered from 246 individuals. In both the COI and 28S data sets, species except for Planococcus citri and P. minor were unambiguously identified by all the methods. The PTP analysis based on COI sequences generated more putative species in Antonina tesquorum, Atrococcus paludinus, and Formicococcus sp. than morphological identification. Among these three cases, the sequences of At. paludinus showed 3.55% variation at the 28S locus, possibly reflecting cryptic diversity in this taxon. Our study corroborates the utility of the COI and 28S genes in the rapid identification of mealybugs, and the barcode library we provide will create an effective identification system for mealybug pest management in China.

Three new fungal species, Septobasidium macrobasidium, S. puerense and S. wuliangshanense, are proposed based on a combination of the morphological features and molecular evidence. The taxon S. macrobasidium is characterized by the coriaceous basidiomata with a cream surface, cylindrical basidia, straight, 4-celled, subglobose or ovoid probasidia and thin-walled, narrowly cylindrical basidiospores with septa, measuring as 7–9 × 3.5–4.5 µm, the haustoria consisting of irregularly coiled hyphae; in addition, this fungus was found associated with the insect of Diaspididae. The species S. puerense is characterised by resupinate coriaceous basidiomata with a cinnamon brown to chestnut brown surface, cylindrical or slightly irregular basidia, 2-3-celled, slightly curved, subglobose to pyriform probasidia, probasidia cell persistent after the formation of the basidia and the haustoria with two types consisting of irregularly coiled hyphae and spindle-shape. The fungus was found associated with the insect species Pseudaulacaspis pentagona. The species S. wuliangshanense is characterised by the coriaceous basidiomata with a slightly brown surface, cylindrical or slightly irregular basidia, 2-3-celled, straight or slightly curved, pyriform, subglobose or ovoid and probasidia, haustoria consisting of irregularly coiled hyphae, associated with the insect genus Aulacaspis. Sequences of internal transcribed spacer region (ITS) were analysed maximum likelihood, maximum parsimony and Bayesian inference methods. The new species S. macrobasidium was clustered with S. maesae. Furthermore, S. puerense was retrieved as a sister to S. carestianum. The phylogenetic tree, inferred from the ITS sequences, highlighted that S. wuliangshanense was the sister to S. aquilariae with strong supports. Application of PHI test to the ITS tree-locus sequences revealed no recombination level within phylogenetically related species.

The Cosmococcus species (Hemiptera: Coccomorpha: Lecanodiaspididae) found in China are reviewed. Based on morphological and molecular data, C. albizziae Borchsenius, 1960 syn. nov. and C. euphorbiae Borchsenius, 1959 syn. nov. are placed as junior synonyms of C. erythrinae Borchsenius, 1959. The wax tests of both sexes and the slide-mounted adult female of C. erythrinae Borchsenius are redescribed.

A new species of false pit scale (Hemiptera, Coccoidea, Lecanodiaspididae), Lecanodiaspis jiangxiensis Zhang & Wang, sp. nov., collected on Castanea mollissima Blume (Fagaceae) in Jiangxi, south China, is described and illustrated based on the morphology of the adult female. A taxonomic key and an updated checklist of false pit scales known from China are provided.

A new species of wax scale, Ceroplastes planoides Li & Wang, sp. nov. (Hemiptera: Coccomorpha: Coccidae), from Yunnan Province, China., is described and illustrated. Phylogenetic analysis based on COI and 28S genes confirms the monophyly of this new species. A key to the currently known species of the genus Ceroplastes in China is provided, along with a discussion on the variation in the number of clear areas within the C. floridensis species group.