Eleanor H. Slifer

The femoral chordotonal organs of a grasshopper, orthoptera, acrididae

SummaryThe fine structure of the prothoracic and mesothoracic femoral chordotonal organs of a grasshopper,Romalea microptera, is described. A single chordotonal organ may contain more than 300 sensory units. Each unit includes the cell bodies and dendrites of two neurons, together with sheath cells of several kinds. The cytoplasm of the sheath cells is packed with microtubules and filaments. These cells surround the cell bodies of the neurons and anchor them to the inner surface of the femoral wall. The dendrites from the two neurons are enclosed by a scolopale cell. At the distal end of this cell they traverse the extra-cellular space within the scolopale and their tips are fitted into cavities in the scolopale cap. The ciliary region of each dendrite is dilated for about one fourth of its total length. The cap is embedded in an elongate cap cell which is attached, in turn, to a ligament cell. The ligament cells are, themselves, attached to an apodeme that extends in from the tibia. When the tibia is flexed, the chordotonal organ is stretched and when it is extended, the organ is relaxed. It is postulated that the mass of the dilated region affects the character of the vibration that is induced when the dendrite is stretched or relaxed.

Spheroid sense organs on the cerci of polyphagid cockroaches (Blattaria: Polyphagidae)

Abstract Conspicuous, bulbous, spheroid sensilla, of unknown function but apparently related to trichobothria, are found on the ventral surfaces of the cerci of some members of Polyphagidae [ Arenivaga (Arenivaga ) spp.; Arenivaga (Psammoblatta ) spp.; Eremoblatta spp.; Polyphaga spp.; Homoeogamia mexicana; Ergaula spp.; Therea petiveriana ]. Spheroid sense organs were not found in 44 genera and 60 species representing the four other families (Cryptocercidae, Blattidae, Blattellidae, and Blaberidae) of Blattaria.

Sense organs on the antennal flagellum of the human louse, Pediculus humanus (Anoplura)

Tactile hairs are present on all three subsegments of the antennal flagellum of the human louse. There is, in addition, a single chemoreceptor (tuft organ) on subsegment 2 and 12 or 13 chemoreceptors (one tuft organ, two pore organs and nine or ten pegs) on subsegment 3. The cuticle surrounding the bases of the pegs at the tip of the antenna is unusual in that parts of it are perforated by many fine pores. This cuticle is underlain by a thin layer of dendrites. This region may also have a chemoreceptor function.

Sense organs on the antennal flagellum of a stonefly (Plecoptera, insecta)

Tactile hairs, small chemoreceptor pegs, thick‐walled chemoreceptors, thin‐walled chemoreceptors of several types, coeloconic sense organs and campaniform sense organs are present on the flagellum of a stonefly, Allocapnia recta (Claassen).

Sense organs on the antennal flagellum of the mimosa webworm, Homadaula anisocentra (Lepidoptera, Glyphipterygidae)

Five different types of sense organs were found on the antennal flagellum of Homadaula anisocentra. These were (1) tactile hairs; (2) thick‐walled chemoreceptors; (3) thin‐walled chemoreceptors of several kinds; (4) styloconic chemoreceptors and (5) small chemoreceptor pegs in shallow depressions. No coeloconic sense organs were seen.

Sense organs on the antennal flagellum of mayflies (Ephemeroptera)

A few very small sensory pegs with the characteristics of chemoreceptors are present in both males and females on the antennal flagellum of the mayflies, Stenacron interpunctatum (Say) Stenacron interpunctatum (Say) is Stenonema interpunctatum (Say) of earlier literature. and Cloeon sp. They are situated near the proximal end of the flagellum on its ventro‐lateral surface and have escaped the attention of earlier investigators.

Sense organs on the antennal flagellum of two species of scorpionflies (Mecoptera)

Abstract The antennal flagellum of Panorpa dissimilis is composed of from 36 to 38 subsegments and that of Bittacus chlorostigma of about 15. Divisions between subsegments are indistinct in Bittacus. Tactile hairs are present on all subsegments in both species. A number of anomalous tactile hairs that are non-innervated and have reduced or no sockets occur on the terminal subsegment (or subsegments) of Bittacus. A few thickwalled and many thin-walled chemoreceptors are present in both species. Panorpa has a large number of long porous chemoreceptors but these are absent in Bittacus. Many coeloconic sense organs are present in Bittacus but none at all in Panorpa. Campaniform sense organs, erratically distributed, are present at the distal end of some subsegments in both species. The more distally located campaniform sensilla are smaller and have irregularly roughened domes.

The maxillary palp organs of a wood-boring beetle, Melittomma sericeum (coleoptera, lymexylonidae)

The complex and conspicuous basket‐like structure attached to the third segment of each maxillary palp of Melittomma sericeum males is densely covered with tactile hairs on its outer or convex surface and with thinwalled chemoreceptors on its inner or concave surface. In a living male the structure is highly mobile and is extended laterally and ventrally. It evidently serves to detect odors produced by the female.