The Scent Glands of the Neotropical Harvestman Discocyrtus pectnifemur: Morphology, Behavior and Chemistry

Segovia, Júlio M.G.; Hara, Marcos Ryotaro; Pagoti, Guilherme Ferreira; Sannomiya, Míriam; Santos, Déborah Yara Alves Cursino dos; Willemart, Rodrigo Hirata

doi:10.1007/s10886-015-0612-8

Cited by 14 publications

(10 citation statements)

References 37 publications

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“…This sexual variation may reflect the fact that female harvestmen may use chemical defenses more often than males (Segovia, Murayama, & Willemart, 2018), and thus they may have ozopores that are easier to access or produce more secretions, while males may rely more upon physical defenses. Although we did not observe any significant sexual differences in ozopore morphology, recent studies have revealed intraspecific variation in the mode and frequency of the release of scent gland secretions (Moore & Townsend Jr., 2019;Nazareth & Machado, 2015;Segovia et al, 2015Segovia et al, , 2018.…”

Section: Discussioncontrasting

confidence: 94%

“…Hara and Gnaspini (2003) noted three mechanisms for the release of scent gland secretions including the evaporation of chemicals from the immediate vicinity of the ozopore, the production of a fine spray or liquid from the ozopore that spreads over the body (forming a chemical shield), or the specific direction of the scent gland secretions by jet emission or by leg dabbing (see Eisner, Jones, Hicks, Silberglied, & Meinwald, 1977;Eisner, Kluge, Carrel, & Meinwald, 1971). Recent studies have found that the frequency of the use of scent gland secretions vary between ovigerous and non-ovigerous females (Nazareth & Machado, 2015) and that at least some species of harvestmen exhibit intraspecific variation with respect to the mechanism of secretion (Moore & Townsend Jr., 2019;Segovia, Hara, Pagoti, & Sannomiya, 2015).…”

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confidence: 99%

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Interspecific, ontogenetic, and sexual variation in ozopore morphology among cosmetid harvestmen (Arachnida, Opiliones, Laniatores)

Townsend

Teevan‐Kamhawi²,

Calpo³

2019

Journal of Morphology

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The ozopores of cosmetid harvestmen rest upon lateral projections of the carapace, have simple or highly reduced channels, and are partially obscured by enlarged dorsal processes associated with coxae I and II. Rather than use scent gland secretions to form a chemical shield on the dorsum, the cosmetid harvestman exhibits a unique defensive behavior known as “leg dabbing” in which the distal tip of tarsus I or II is dipped into fluid that accumulate at the base of coxa II and the droplet on the tarsus is pointed toward the predator. Relatively little is known about interspecific variation in ozopore morphology among cosmetid harvestmen. In this study, we used scanning electron microscopy to examine the ozopores of males and females of nine species as well as those of antepenultimate nymphs for two species. Among adults, we found differences between species in the shapes of the ozopores (round or subtriangular), the morphology of the dorsal and lateral channels (if present), and the relative size, shape and armature of the dorsal posterior process (dpp) of coxa I and the dorsal anterior process (dap) of coxa II. Our observations suggest that the morphology of dpp I and dap II could be sources for systematic characters in future phylogenetic studies of the Cosmetidae. We observed ontogenetic differences but relatively little intersexual variation in the morphology of the ozopore. The ozopores of nymphs are generally more oval than those of adults and the opening of the ozopore of the nymph is less obstructed, if at all, by the dorsal coxal processes of legs I–II. These morphological differences suggest that nymphs may use scent gland secretions in a manner different from that of adults.

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Section: Discussioncontrasting

confidence: 94%

mentioning

confidence: 99%

Interspecific, ontogenetic, and sexual variation in ozopore morphology among cosmetid harvestmen (Arachnida, Opiliones, Laniatores)

Townsend

Teevan‐Kamhawi²,

Calpo³

2019

Journal of Morphology

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“…Harvestmen are well known for their repugnatorial glands and defensive chemicals (Gnaspini & Hara, 2007;Raspotnig et al, 2014;Segovia et al, 2015a). However, it has been reported that, unexpectedly, such secretions are not used against all predators: in more than a hundred interactions between armored harvestmen and spiders, only a single harvestman released defensive secretions (Souza & Willemart, 2011;Carvalho, Souza & Willemart, 2012;Dias & Willemart, 2013).…”

Section: Discussionmentioning

confidence: 99%

“…Harvestmen (Arachnida, Opiliones) are mostly nocturnal organisms known for their chemical defenses (Gnaspini & Hara, 2007;Nazareth & Machado, 2015;Segovia et al, 2015a), but that actually have an array of defensive mechanisms. For some species of the suborder Laniatores, a thick armor is the primary defense mechanism (Souza & Willemart, 2011;Dias & Willemart, 2013;Segovia, Del-Claro & Willemart, 2015b), but they may also freeze (Chelini, Willemart & Hebets, 2009), flee or retaliate both chemically and mechanically, during which they may bite and pinch with their chelicerae or pedipalps and pinch with spines on legs IV (Gnaspini & Hara, 2007).…”

Section: Introductionmentioning

confidence: 99%

Sticky flatworms (Platyhelminthes) kill armored harvestmen (Arachnida, Opiliones) but are not immune to the prey′s weapons

2018

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Asking how prey respond to different species of predators helps understanding the repertoire of defenses prey exhibit. This approach may also add to the knowledge on the efficiency of prey′s defenses against each predator and allows studying the costs of being attacked by different predators. Here, we studied interactions between the predatory terrestrial flatworm Cephaloflexa bergi and the harvestman Mischonyx cuspidatus. The flatworm quickly strikes at the prey′s leg with its head, then crawls towards the prey′s body releasing mucus and thus subdues the harvestman. Harvestmen may release defensive chemicals and pinch the flatworm with spines on legs IV, sometimes cutting the predator in two pieces. We also experimentally assessed the benefits of harvestmen′ defense and the cost of being attacked by testing whether the chemical defense of the harvestmen is efficient against the flatworm and whether the harvestmen that had survived a flatworm attack would have their locomotion abilities hampered. Both hypotheses were corroborated. Previous studies on interactions between harvestmen and other predators, such as spiders and scorpions, had shown that defensive secretions and mechanical retaliation were seldom used and were often ineffective. Our results point to the exact opposite and suggest that different predators exert different selective pressures culminating in the array of defenses exhibited by the prey.

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“…Harvestmen have two main strategies of transmitting defensive compounds: (1) create a chemical shield around the body, and (2) direct the liquid toward the offending agent, i.e. 'jet emission' (Segovia et al 2015). These strategies are variable among harvestmen (Gnaspini & Hara 2007).…”

Section: Transmission Of Chemical Signals In Harvestmenmentioning

confidence: 99%

Chemical communication and ecology in Eupnoi harvestmen

Escalante

2019

Preprint

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Communication via chemical signals and cues is a widespread modality in animals. Producing, transmitting, receiving and processing chemical compounds impose important challenges. Nonetheless, certain arthropods rely almost exclusively on this channel for intra- and inter-specific communication. Through a preliminary literature review, I summarize here the morphological, behavioral and evolutionary implications of chemical communication in harvestmen (the arachnid order Opiliones), with particular emphasis in one group: the Eupnoi or “Daddy Long-legs”. This group has a unique secretory gland that opens in an ozopore in their dorsum. While relying mostly on short-range olfaction and contact chemoreception using different setae, some harvestmen are known to use chemicals in defense, alarm, spatial marking, recruitment, or reproduction. I then propose future research direction on the mechanisms of production and the evolutionary history of these traits. Specific questions can include (1) are chemical signals used as alarm pheromones in Eupnoi aggregations? (2) Do harvestmen rely on chemicals to mark their traditional roosting sites? If so, what are the chemicals involved and how do those differ from the ones used as alarm signals? Also, (3) what are the specific functions of the chemical communication during in female-male communication and multi-specific roosting aggregations? And (4) to what extent the use of chemical defenses imposes a trade-off with other defense mechanisms such as ‘playing dead’ or voluntarily releasing legs. Overall, these harvestmen provide a unique opportunity to test comprehensive and interdisciplinary hypotheses to understand the evolution of chemical communication, as well as the importance of chemical ecology on species diversification in arthropods.

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The Scent Glands of the Neotropical Harvestman Discocyrtus pectnifemur: Morphology, Behavior and Chemistry

Cited by 14 publications

References 37 publications

Interspecific, ontogenetic, and sexual variation in ozopore morphology among cosmetid harvestmen (Arachnida, Opiliones, Laniatores)

Interspecific, ontogenetic, and sexual variation in ozopore morphology among cosmetid harvestmen (Arachnida, Opiliones, Laniatores)

Sticky flatworms (Platyhelminthes) kill armored harvestmen (Arachnida, Opiliones) but are not immune to the prey′s weapons

Chemical communication and ecology in Eupnoi harvestmen

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