Fine Morphology of the Mouthparts in Cheilocapsus nigrescens (Hemiptera: Heteroptera: Miridae) Reflects Adaptation for Phytophagous Habits

To obtain a better understanding of feeding adaptations, the fine structure of the mouthparts in adults of Cheilocapsus nigrescens Liu and Wang, including the sculpture and interlocking mechanisms of the stylets and distribution and abundance of sensilla located on the labium, were studied using scanning electron microscopy. The mouthparts are similar to those of previously studied mirid species in most aspects and composed of a cone-shaped labrum, a tube-like, four-segmented labium with a deep groove on the anterior side, and a stylet fascicle consisting of two mandibular and two maxillary stylets. Each mandibular stylet tip has about 6–8 indistinctive notches, which help in penetrating the leaf surface. A series of transverse squamous textures are present on the adaxial surface of the mandibular stylets. The maxillary stylets interlock to form a food canal and a salivary canal, equipped with an external longitudinal process that engages grooves in the mandibular stylets. Three kinds of sensilla, including four types of sensilla basiconica (I, II, III, and IV), four types of sensilla trichodea (I, II, III, and IV), and one type of sensillum campaniformium, occur at different locations on the labium. Among them, sensilla trichodea I and II are the most abundant; sensilla basiconica II occurs between the first segment and second segment, and between the third and fourth segment. The tripartite apex of the labium consists of two lateral lobes and an apical plate. Each lateral lobe possesses a field of 11 sensilla basiconica IV and 1 sensillum trichodeum IV. The morphology of the mouthparts and the distribution of sensilla located on the labium in C. nigrescens are discussed with respect to their possible taxonomic and functional significance. In particular, the indistinct notches of the mandibular stylet and smooth inner surface of the right maxillary stylets are suited primarily for phytophagy.

The antennal sensilla of the carnivorous "phantom" larva of Chaoborus crystallinus (De Geer) (Diptera, Nematocera)

The prehensile antennae of larval Chaoborus crystallinus are equipped with seven sensilla that comprise 24 sensory cells. Analysis of their ultrastructure indicates that they represent either mechano-or chemo-receptors. The main chemosensory input is established by a compound sensillum, S15 ("sensory cone" with 15-sensory cells), that is located at the tip of the antennal article (outer ventral claw). Exteroreceptors are the "middle claw" of the antenna, and a small sensillum trichodeum at half the length of the antennal article. Proprioreceptive mechanoreceptors are found in the proximal and distal regions of the antennal article. Comparison of sensillar arrangement and ultrastructure indicates that the ancient sensillar equipment of the culicid type is still present within the highly specialized catching apparatus of C. crystallinus. Compared with Culicidae, chemosensitive input is reduced, while proprioreceptive, mechanosensory input is highly developed. Larvae of Culicidae and Chaoboridae appear to possess a homologous set of antennal senilla that show specializations connected to the different functions of the antennae.

Scanning Electron Microscopy of antennal sensilla of the Japanese tusser, Antheraea vamamai

Antennal surface structure of the Japanese tusser, Antheraea yamamai was observed by scanning electron microscope. The antennae of male and female were bipectinate with scape, pedicel and 33--37 flagellar segments. There were two pairs of equal long branch on eacli flagellar segment of male (Fig.1), but a pair of longer and a pair of shorter on female's (Fig.2).Seven types of sensillum, namely sensillum trichodeum, sensillum cheaticum, sensillum coeloconicum, sensillum campaniformlum, sensillum styloconicum, Bohm's bristle and sensillum squamiformium wer found on the antenna both of male and female. The sensillum trichodeum could be subdivided into long and short according to the shape and surface substructure. The long sensillum trichodeum had a diameter of 4.8μm at its base. It was reratively stright and slightly curved at the tip (Fig.3). The short sensillum trichodeum was 2.5--3.6 μm in diameter at the base. It was shorter, strongly bend down near its base and run parallel with the surface of the antenna (Fig.4). The surface of long and short sensilla trichodea were covered with annular ridges (Fig.5).