ABSTRACT We describe a gland in the arthrodial membrane of the coxa-trochanter articulation in the fourth pair of legs in the Neotropical harvester Mischonyx squalidus Bertkau, 1880. Externally the glandular area has a rough appearance with pores on its surface, with folds of the arthrodial membrane. Internally, its secretory cells have spherical secretory vesicles, smooth endoplasmic reticulum, mitochondria and ducts that exit from the cells and cross the arthrodial membrane. Histochemical tests indicate the presence of proteins and neutral glycoproteins. The function of the gland might be to produce lubricating products that allow better movement of the coxa-trochanter region.

Abstract Background: Scorpionism is a worldwide problem that has already made thousands of victims, and multi-disciplinary approaches for controlling their populations are to be more successful. Hens are often mentioned as tools for controlling scorpions; however, systematic/experimental behavioral studies are not available. Moreover, there is no systematic information on the effect of scorpion venoms on hens. Using the venomous yellow scorpion Tityus serrulatus, the present study aimed to clarify the following aspects: (1) voracity of hens, (2) how hens react when stung, (3) the effect of scorpion stings on hen behavior during attacks, and (4) hen survivorship after feeding on scorpions. Methods: We attracted hens with corn powder, offered them scorpions and then recorded the hen-scorpion interaction. To test the effects of the sting we manually removed the scorpion’s telson. Results: We found that some hens ate up to six scorpions within minutes. By means of an ethogram and drawings, we showed that they exhibited several aversive behaviors when capturing scorpions. Removal of the scorpion telson stopped the aversive reactions, which was not observed in the control group. Finally, hens did not exhibit atypical behaviors after 1, 7 and 30 days and were all alive after 30 days. Conclusion: This is the first empirical and video recorded study providing evidence that hens are clearly affected by scorpion venom but do not die. Therefore, they may have potential to be used in biological control of these arthropods.

A falta de dados de história natural por vezes dificulta estudos filogenéticos sobre a evolução do comportamento. Nesse estudo nós fornecemos dados quantitativos de campo sobre forrageamento e sítios de oviposição de um opilião Neotropical pertencente a uma subfamília com uma filogenia publicada, Goniosomatinae. Heteromitobates discolor passa o dia em rochedos graníticos em rios, onde deposita os ovos em áreas abrigadas e escuras. A fêmea cuida dos ovos e responde agressivamente a fêmeas co-específicas que se aproximam. Na ausência de fêmeas, formigas, co-específicos e percevejos reduvídeos podem predar os ovos. Fêmeas que guardam ovos não deixam as desovas, mas machos e fêmeas sem ovos deixam os rochedos graníticos e forrageiam sobre a vegetação è noite, próximos è margem do rio e sem diferença nos sítios explorados entre os machos e as fêmeas. As características gerais descritas em H. discolor são similares ao que tem sido reportado para outras espécies nesta subfamília, sugerindo um conservadorismo evolutivo dentro do grupo.

The lack of data on the natural history often hampers phylogenetic studies on the evolution of behavior. Herein we provide quantitative field data on foraging and oviposition sites of a Neotropical harvestman belonging to a subfamily with a published phylogeny, Goniosomatinae. Heteromitobates discolor rests during the day on granitic boulders on rivers, laying eggs in sheltered and darker areas. The female guard the eggs and aggressively respond to approaching conspecific females. In the absence of the female, ants, conspecifics and reduviids may predate the eggs. Egg-guarding females are known not to leave the clutch, but males and non-guarding females may leave the granitic boulders and forage on the vegetation at night, close to the river margins and with no difference in the sites explored between males and females. The general features described in H. discolor are similar to what has been reported for other species in this subfamily, suggesting an evolutionary conservatism within the group.

Harvestmen feed on live, dead and fresh, or decomposing animals, fungi, and plant matter, being very dependent on chemoreception to find food. Herein we performed an experiment to test if individuals of Discocyrtus pectinifemur Mello-Leitão, 1937 (Gonyleptidae) (n = 23) behave differently when in contact with olfactory cues from different sources (rotten prey, non-rotten prey and a control). Using dead crickets in a box covered with a mesh, and recording the time the harvestmen spent in the vicinities of the box, we show that D. pectinifemur detects non-rotten prey and stays longer on it than on the other two treatments. Our results contrast with a previous study on another species, showing that we should not generalize results obtained for one species. Our data also suggest that olfactory receptors occur on the legs of these harvestmen and that D. pectinifemur might choose dietary items based on olfaction.