XIII. On certain Sensory Organs in Insects, hitherto undescribed*.

Abstract

Read May 3rd, 1860 Jt.. BEFORE proceeding to the details of the following communication, it will be well to remind this Society of the structures I have already pointed out as existing in the Insect tribes, the consideration of which will serve to explain the nature of the new organs about to be described. I n a paper read before the Linnean Society on the 17th June, lS56+, I called attention to groups of hemispherical vesicles, disposed in rows, very regularly arranged, situated at the base of the hccltems in all Diptera. These vesicles are apparently formed of cuticle, beneath which the ordinary chitine-layer is deficient, whereby a longer or shorter tube is formed, according to the thickness of that layer at the part. I showed that the number of these vesicles in some Diptera was great-sometimes as many as 360 on each halter. I also pointed out that a very considerable nerve (the largest in the body except the optic) proceeded to the 7zalter. I then, as also subsequently (Linn. Trans. vol. xxii. p. 144), showed that similar structures were to be found extending along the subcostal nervure of the wings both of Diptera and of the 4-winged tribes ; more numerously in that of the posterior wings and on the upper aspect. To these organs also nerves were clearly seen to pass from the thoracic ganglia. At the same time I showed that the elytra of the Coleoptera formed no exception in consequence of their peculiar structure, but that the nerve, entering their base, branched into numerous filaments, which ultimately terminated in vesicles pretty uniformly scattered on the upper surface. At the time of reading that paper I had not found these organs on the under surface of the elytron, but I now furnish a drawing of the under surface of that of Aromia moschata (Musk Beetle), in which the vesicles are distributed in the course of the nervure, the nerve giving off branches t o each vesicle (Pl. XVIII. fig. B). Although I had distinctly perceived the branches of the nerves passing to the vesicles on the subcostal nervure of the wings and on the elytra, I had not, at the time of my first notice of the subject, seen the nerves actually distributed to those more elaborate groups on the base of the halteres. I now, however, am able to show this point most clearly in the halteres of Q3strzcs Eqzci (Pl. XVIII. fig. A). It will be seen that a branch passes directly to each of the three principal groups at the base, while a small nerve only proceeds up to the head of the organ. Thus it is proved that, whatever the function of these organs may be, the largest nerve, except the optic, is distributed to them. Having pursued these investigations into the different members of insects, I beg now * It should be stated, that this paper was originally presented to the Royal Society, where it was read on the 26th t Journ. of Proceed. Linn. SOC., vul. i. p. 136.

Morphology and histology of vom Rath's organ in brush-footed butterflies (Lepidoptera: Nymphalidae)

“…The form of the invagination was not described by Stange et al [26], Song et al [30], Bogner [39], or Stange [40]; or was erroneously reported as bottle-shaped by Kent et al [23], Chen & Hua [29], and Zhao et al [27]. For this purpose, we consider as a bottle-shaped form only the cases of the unidentified geometrid reported by Hicks [2]; "Pieris sp. ", probably P. rapae or P. brassicae [4]; and F. ryphea (Fig 14).…”

“…If the bottom of the atrium is rounded, then the form is drop-shaped, as in Morpho helenor achillaena (Fig 16). Tubular vom Rath's organs have more or less the same width from the opening to the bottom of the cavity, so they do not form an atrium; examples are Argynnis paphia (Nymphalidae: Heliconiinae) [2] and Cactoblastis cactorum (Pyralidae) [26]. Finally, tapered vom Rath's organs have an opening wider than the bottom of the cavity, forming a funnel, but not an atrium, as in Helicoverpa armigera [27] and Mythimna separata (Noctuidae) [28].…”

“…These are the first reports of the absence of vom Rath's organ in members of Lepidoptera. Hicks [2] reported that vom Rath's organ was absent in Acherontia atropos (Sphingidae). However, vom Rath [4] described the organ of this species, which is probably sacculiform.…”

“…Among these is a depression on the distal segment of the labial palps, known as vom Rath's organ. The pioneer works of Hicks [2] and vom Rath [3,4] reported that the form of the organ varies among species and genera. Both authors mentioned that they analyzed a large number of species, but described few examples: Acherontia atropos (Linnaeus, 1758) (Sphingidae), Malacosoma neustria (Linnaeus, 1758) (Lasiocampidae), Argynnis paphia (Linnaeus, 1758) (Nymphalidae: Heliconiinae: Argynnini), and an unidentified geometrid [2]; and A. atropos, Agrius convolvuli Linnaeus, 1758 (Sphingidae), and Pieris sp.…”

“…Morpho helenor achillaena (Hübner, [1819]) (Satyrinae: Morphini) (♂), cs = coeloconic sensilla, cg = cell groups, o = opening, scale bar 20 μm. https://doi.org/10.1371/journal.pone.0231486.g031PLOS ONEHicks[2] documented the presence of a tubular vom Rath's organ in Argynnis paphia (Heliconiinae: Argynnini). This is also confirmed in the present study(Figs 11, 25 and 26), with Euptoieta hegesia(Figs 12, 27 and 28)representing the second record for the tribe.…”