1463-6395 10.1111/j.1463-6395.2008.00341.xWillemart, R. H., Farine, J.-P. and Gnaspini, P. 2008. Sensory biology of Phalangida harvestmen (Arachnida, Opiliones): a review, with new morphological data on 18 species. 2014Acta Zoologica (Stockholm) 90: 2092013227 Phalangida includes three of the four suborders of Opiliones (Arachnida): Eupnoi, Dyspnoi and Laniatores. We review the literature on the sensory structures and capabilities of Phalangida, provide new morphological data for 18 species and discuss the 11 sensory structures that have been described in the group. Based on the published data encompassing both behaviour and morphology, three conclusions are apparent: (1) species of Phalangida appear to have limited abilities to detect stimuli at a distance; (2) close range olfaction probably helps to find foods with strong odours, but (3) they appear to be highly dependent on contact chemoreception to detect live prey, predators and mates. We also highlight the fact that legs I in the three suborders and pedipalps in Dyspnoi and Eupnoi are very important sensory appendages, thus legs II should not be called the 'sensory appendages' of harvestmen. In conclusion, we highlight the fact that the sensory capabilities, diet, prey capturing and handling ability, and foraging behaviour of species of Phalangida seem to be different from those of most other arachnids. Finally, we suggest future directions for studies in the field of the sensory system of the group

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We studied the sensory structures and tegumental glands of two harvestmen species, Neosadocus sp. and Iporangaia pustulosa. We also provide field data of dietary items and data on the foraging behavior of Neosadocus sp. in captivity. Food include mostly immobile items such as dead insects, fruits and feces; the mobility of foraging animals in starvation was greater than in satiation conditions; no trichobothria was found; metatarsal paired slit sensilla and three other sensilla are described for the first time in harvestmen. We discuss the possible relationship between sensory structures, diet and foraging mobility, comparing with other groups of Arachnida. We also describe five new tegumental glands, one sexually dimorphic in the metatarsus IV of I. pustulosa males and two that are rubbed against the substrate while walking, present in both species. This is the first morphological evidence that harvestmen might leave chemical marks on the substrate.

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In various animal species, male sexual dimorphic characters may be used during intrasexual contests as ornaments to attract females, or to hold them before, during, or after copulation. In the well-known harvestman, Phalangium opilio L., 1758, the behavioral functions of these male sexually dimorphic structures have never been studied in detail. Therefore, in addition to a morphometric study, 21 male contests and 43 sexual interactions were analyzed. Our observations revealed that during contests, the male cheliceral horns form a surface by which the contestants use to push each other face-to-face while rapidly tapping their long pedipalps against the pedipalps of the opponent, occasionally twisting the opponent's pedipalp. Scanning electron micrographs revealed contact mechanoreceptors on the pedipalp that would detect the intensity–frequency of contact with the contender's pedipalp. Larger males won almost all contests, whereas the loser rapidly fled. During sexual interactions, the longer pedipalps of the male held legs IV of the female, whereas males with shorter pedipalps held the female by legs III. No contact with the male pedipalps and chelicerae by the females was visible before, during, or after copulation. Soon after copulating, males typically bent over the female, positioning their cheliceral horns against the females's dorsum. Consequently, our data show that the cheliceral horns and the longer pedipalps of the male seem to play an important role, during both intersexual and intrasexual encountering. Résumé : Chez de nombreuses espèces animales, les ornementations sexuellement dimorphiques des mâles peuvent être utilisées lors des combats rituels entre mâles ou comme signal afin d'attirer les femelles ou les retenir avant, pendant et après l'accouplement. Chez l'opilion Phalangium opilio L., 1758, le rôle précis joué par ces structures n'a jamais été mis en évidence. Au cours de ce travail, outre une étude morphométrique, nous avons analysé, grâce à des enregistrements vidéo, 21 combats entre mâles et 43 accouplements. Nous avons pu montrer que, lors des combats, les mâles utilisent les cornes portées par les chélicères pour se repousser lorsqu'ils sont face-à-face, tout en se tapant mutuellement à l'aide de leurs longs pédipalpes, voire en les enroulant avec ceux de l'adversaire. Des micrographies réalisées au microscope électronique à balayage révèlent l'existence de mécanorécepteurs sur les pédipalpes qui pourraient permettre au mâle de détecter la fréquence et l'intensité des contacts des pédipalpes de son adversaire. Les mâles les plus grands gagnent presque tous les combats, le perdant fuyant rapidement. Au cours du comportement sexuel, les mâles à grands pédipalpes les utilisent pour agripper les pattes IV de la femelle, alors que les mâles à pédipalpes plus courts les retiennent par les pattes III. Il n'y a aucun contact tactile de la part des femelles avec les pédipalpes et les chélicères des mâles avant, pendant et après l'accouplement. Juste après l'accouplement, le mâle s'appui...