Sexually dimorphic tegumental gland openings in Laniatores (Arachnida, Opiliones), with new data on 23 species

Abstract

Sexually dimorphic glands often release sexual pheromones both in vertebrates and invertebrates. Species of Laniatores (Arachnida, Opiliones) seem to depend on chemical communication but few studies have addressed this topic. In this study, we review the literature for the Phalangida and present new data for 23 species of Laniatores. In 16 taxa, we found previously undescribed sexually dimorphic glandular openings on the femur, patella, metatarsus, and tarsus of legs I and metatarsus of legs III and IV. For the other species, we provide scanning electron micrographs of previously undescribed sexually dimorphic setae and pegs located on swollen regions of the legs. We also list additional species in which males have swollen regions on the legs, including the tibia, metatarsus, and tarsus of legs I, trochanter and tibia of legs II, femur, metatarsus, and tarsus of legs III, and metatarsus and tarsus of legs IV. The function and biological role of the secretions released by these glands are discussed.

A scanning electron microscopic survey of the cuticle in Cyphophthalmi (Arachnida, Opiliones) with the description of novel sensory and glandular structures

“…They may have some mechanical function. The ventral glandular openings are structurally very similar to structures described in Laniatores (Willemart et al 2010) and are also present in the tarsus of the leg but it is still premature to speculate about their function. Future behavioral studies may help understanding the exact role of these sexually dimorphic structures in cyphophthalmids.…”

The harvestman tarsus and tarsal flexor system with notes on appendicular sensory structures in laniatores

“…Although they do possess a pair of simple median ocelli, harvestmen rely heavily on mechanical and chemical cues (Acosta and Machado, 2007;Willemart et al, 2009). The external surface of the leg contains an abundance of sensory structures and tegumental gland openings (Willemart et al, 2007(Willemart et al, , 2009(Willemart et al, , 2010. Many of the setae are considered mechano-or chemoreceptors, but there is a paucity of histological evidence confirming this for harvestmen (but see Guffey et al, 2000) and these sensory structures are better-known for Acari Coons and Alberti, 1999), Amblypygi (Santer and Hebets, 2011), and Araneae (Foelix, 2011).…”

Experimental test of the mechanism underlying sexual segregation at communal roosts of harvestmen (Prionostemma spp.)

“…An alternative hypothesis is that the sexes differ in the quantity or quality of scent‐marking chemicals and that individuals of one or both sexes are preferentially attracted to same‐sex scent marks (Grether et al., ). Sexually dimorphic scent glands have been described in harvestmen (Murayama & Willemart, ; Willemart, Perez‐Gonzalez, Farine, & Gnaspini, ), and Prionostemma sp. 2 have been observed rubbing against the substrate at roosting sites, a possible scent‐marking behavior (Donaldson & Grether, ).…”