Integrative taxonomy to investigate species boundaries within Culicoides (Diptera: Ceratopogonidae): a case study using subgenus Avaritia from Australasia and Eastern Asia.

In this study, species boundaries were examined for 15 described and 2 undescribed species within the economically important Culicoides subg. Avaritia Fox from Australasia and Eastern Asia. We used an integrative taxonomic approach incorporating DNA barcoding, nuclear gene sequencing, and retrospective morphological analyses. Some arbovirus vector species such as Culicoides fulvus Sen and Das Gupta and Culicoides wadai Kitaoka were genetically and morphologically uniform across sampled distributions, but others including Culicoides actoni Smith and Culicoides brevipalpis Delfinado contained 2 or more genetically independent populations of 'cryptic species' that in some cases were sympatric. Some of these 'cryptic species' exhibited consistent morphological differences, while differences are yet to be found for others species. Additionally, an undescribed species, C. Avaritia sp. No. 3, was found to be synonymous with C. fulvus. These results refine our understanding of the distribution of individual species of C. subg. Avaritia and demonstrate that species descriptions and distribution records need revision for part of the Culicoides fauna. Furthermore, because vector competence studies for most of these species are based entirely on Australian populations, the competence of the putative cryptic species identified elsewhere will require independent assessment. Finally, integrative taxonomic assessment requires genetic and morphological assessment of material from the type localities in order to clarify the status and distribution of species, especially for clades containing cryptic species. International collaboration is needed to facilitate this research.

Morphology, distribution, and abundance of antennal sensilla of male and female macropterous and brachypterous small brown planthopper, Laodelphax striatellus (Fallén) (Hemiptera: Delphacidae).

The antennal sensilla of both genders of macropterous and brachypterous adults of the small brown planthopper, Laodelphax striatellus (Fallén) (Hemiptera: Delphacidae) were examined using light and scanning electron microscopy. Scanning electron microscopy revealed seven types of antennal sensilla in adult L. striatellus which were not evenly distributed on all antennal segments. Sensilla chaetica, a sensillum campaniformium and a Böhm bristle were found on the scape. Sensilla chaetica, sensilla trichodea, sensilla placodea which always present as plaque organs, sensilla basiconica and a sensillum campaniformium were present on the pedicel. Three sensilla basiconica and one sensillum coeloconicum containing two sensory pegs were located on the swollen sensory region of the basal flagellum. Pores observed on the surface of s. trichodea and s. placodea suggest these organs probably play a role in olfaction, whereas the aporous s. chaetica with flexible sockets probably function as mechanoreceptors. The aporous s. basiconica with inflexible sockets are probable to be thermo-hygroreceptors while the Böhm bristle and s. campaniformia may act as antennal proprioceptors. The function of s. coeloconicum remains uncertain. The numerical dominance of antennal olfactory receptors suggests olfaction is an important function of the antenna in L. striatellus. Although a small degree of sexual/wing dimorphism was observed in the numbers of sensilla and in the length and width of antennae and antennal segments, the basic shape and structure of the antennae and antennal sensilla did not differ between the gender or wing form in L. striatellus.