A new structure on the frons of male adults of the Asian rice spittlebug Callitettix versicolor (Hemiptera: Auchenorrhyncha: Cercopidae)

A new structure, here tentatively named the “frontal gland,” specifically found on frons of male adults of the Asian rice spittlebug, Callitettix versicolor (Fabricius, 1794) (Hemiptera: Auchenorrhyncha: Cercopidae), is reported. Adult C. versicolor is distinctly dimorphic in frons morphology. The frons in female adults, like that in most cercopid species, is normally swollen and nearly bulbose and is covered with short pilosity, while the frons in male adults is visibly different, with the lower 3/5 of the postclypeus and anteclypeus being centrally flat, bare and smooth on the surface. SEM observations revealed that the flat frons surface of the male adults is covered with numerous, very fine pores. In total, each frons has over 4500 pores on the central flat area, with an average density of 55.5 ± 1.50 pores per 100 µm2. The distance among the pores averages 10.63 ± 1.8 µm. Each pore unit is composed of a round, deep cavity in which one central conical process is set. The cavity is delimited by a cuticular rim and the opening of the cavity averages 2.89 ± 0.20 µm in diameter. The central, conical process has a sponge-like apex and measures 2.52–2.70 µm in diameter. In addition, one or two (two in most cases) extremely fine pits (0.42–0.56 µm in diameter) are located on the marginal cuticle rim surrounding the cavity and its central conical process. These cuticular, fine pits are located proximal to the pores, at a distance of 0.98–1.96 µm. These porous structures are not present on the frons in female adults. They are assumed to be an exocrine gland system and are possibly the male sex pheromone-releasing glands, as they are only present in male adults. Observations of mating behavior showed that it is likely that the secretions made by the frontal gland constitute short-range attractants and may fulfil aphrodisiac functions to stimulate mating. The species of Auchenorrhyncha were previously thought to communicate via acoustic signals, but the findings described here suggest that at least one Auchenorrhynchan species also uses chemicals for sexual communication.

Does the frontal sensory organ in adults of the hoplonemertean Quasitetrastemma stimpsoni originate from the larval apical organ?

Background The apical organ is the most prominent neural structure in spiralian larvae. Although it has been thoroughly investigated in larvae of the class Pilidiophora in phylum Nemertea, studies on its structure in other nemertean larvae are limited. Most adult hoplonemertean worms have a frontal organ located in a position corresponding to that of the larval apical organ. The development and sensory function of the frontal organ has not been thoroughly characterized to date. Results The apical organ in the early rudiment stage of Quasitetrastemma stimpsoni larvae consists of an apical plate enclosed by ducts of frontal gland cells and eight apical neurons. The apical plate is abundantly innervated by neurites of apical neurons. During the late rudiment stage, the larval apical organ has external innervation from below by two subapical-plate neurons, along with 11 apical neurons, and its plate contains serotonin-like immunoreactive (5-HT-lir) cells. In the vermicular stage (free-swimming juvenile), the number of apical neurons is reduced, and their processes are resorbed. Serotonin is detected in the apical plate with no visible connection to apical neurons. In adult worms, the frontal organ has a small apical pit with openings for the frontal gland ducts. The organ consists of 8 to 10 densely packed 5-HT-lir cells that form the roundish pit. Conclusions Although the ultrastructure of the Q. stimpsoni larval apical organ closely resembles that of the apical organ of Polycladida larvae, the former differs in the presence of flask-shaped neurons typical of Spiralia. Significant differences in the structure of the apical organs of hoplonemertean and pilidia larvae point to two different paths in the evolutionary transformation of the ancestral apical organ. Ultrastructural and immunoreactive analyses of the apical organ of a hoplonemertean larva in the late rudiment and vermicular stages and the frontal organ of the adult worms identified common morphological and functional features. Thus, we hypothesize that the larval apical organ is modified during morphogenesis to form the adult frontal organ, which fulfills a sensory function in the hoplonemertean worm. This unique developmental trait distinguishes the Hoplonemertea from other nemertean groups.

Tonsuritermes, a new soldierless termite genus and two new species from South America (Blattaria: Isoptera: Termitidae: Apicotermitinae)

A new genus, Tonsuritermes Cancello & Constantini gen. nov., is described from South America. The main morphological features of the new genus are a remarkable frontal gland and protibia with two rows of spine-like bristles. Two new species of Tonsuritermes are described: T. tucki Cancello & Constantini sp. nov. and T. mathewsi Cancello & Constantini sp. nov. Comparisons, measurements, a map, histology of the frontal gland, and illustration of all fundamental morphological aspects are provided.

Chemical Composition and Biological Activities of Soldiers of the Brazilian Termite Species, Nasutitermes macrocephalus (Isoptera: Natutitermitinae)

The defensive secretion of the frontal gland from termite soldiers is a mixture of monoterpenes, sesquiterpenes and diterpenes, the latter being the most representative. Analyses of the dichloromethane extract from soldiers of the Brazilian termite, Nasutitermes macrocephalus (Silvestri, 1903) (Isoptera, Nasutitermitinae), described for the first time, allowed to identify the presence of two monoterpenes (α-pinene and limonene) and two sesquiterpenes (β-trans- caryophyllene and α-selinene) by GC-EIMS, and the isolation of one rippertane and six trinervitane diterpenes by RP-HPLC. The chemical structures of the purified compounds were elucidated by interpretation of their spectroscopic data (1D and 2D NMR, EIMS, HRESIMS, and specific optical rotation) and the complete unequivocal assignment of the 3α-hydroxy-trinervita-1(15),8(19)-dien-2-one (6) was included in this paper, to complement the lack of information in the literature. Antibacterial, antifungal and cytotoxicity against cancer cell lines activities were evaluated. In particular, the compounds 2α,3β-dihydroxy- trinervita-1(15),8(19)-diene (2) and 3α-hydroxy-15-rippertene (7) exhibited the better activities against the clinically isolated Gram-positive bacterium methicillin-resistant Staphylococcus aureus BMB 9393, both with a MIC value of 31.2 μg mL−1. This is the first description of a rippertane diterpene (7) as an antibacterial agent.