Male dimorphism and alternative reproductive tactics in harvestmen (Arachnida: Opiliones)

Buzatto, Bruno A.; Machado, Glauco

doi:10.1016/j.beproc.2014.06.008

Cited by 58 publications

(49 citation statements)

References 106 publications

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“…The material examined has been deposited in the Colección Nacional de Arácnidos (CNAN) UNAM, Mexico; American Museum of Natural History (AMNH), New York, USA; Texas Memorial Museum (TMM), Texas, USA, and Museo Argentino de Ciencias Naturales (MACN), Buenos Aires, Argentina. We adopted the terms alpha and beta male commonly used for Opiliones (Kury, , ; Ferreira & Kury, ; Kury & Ferreira, ; Ázara, DaSilva & Ferreira, ) and equivalent to Major/Minor males (Zatz et al ., ; Buzatto & Machado, ) to describe the dimorphic male condition in which larger, more strongly armed males (= alpha) are distinct from smaller, weakly armed males (= beta). One beta male of J. pecki comb.…”

Section: Methodsmentioning

confidence: 99%

When troglomorphism dupes taxonomists: morphology and molecules reveal the first pyramidopid harvestman (Arachnida, Opiliones, Pyramidopidae) from the New World

2016

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Cavernicolous species that exhibit a high degree of troglomorphism often provide some of the most intriguing evolutionary riddles. For such taxa, the correct systematic arrangement is difficult to determine and becomes problematic when based solely on highly convergent external morphological characters, leading to exaggerated support of spurious relationships. For the arachnid order Opiliones, examination of male genitalia morphology often aids in determining the family to which a particular taxon belongs. However, many taxa described prior to the 1990s lack detailed descriptions or drawings of this important character and, for highly‐derived species, it is may still be necessary to seek support from additional sources of characters (e.g. molecular data) to accurately assess systematic placement. The enigmatic species Stygnomma pecki Goodnight & Goodnight, from a cave in Belize proved to be especially difficult to place based on morphological characters alone. Thus, using a previously published dataset for laniatorean harvestmen, we carried out a robust phylogenetic analysis aiming to determine the evolutionary relationship of this Neotropical troglomophic species. Informed by the results of the molecular phylogenetic analysis of 88 terminals representing Laniatores, we describe Jarmilana gen. nov. and provide a redescription of the type species Jarmilana pecki (Goodnight & Goodnight, ) comb. nov. Morphological evidence, including male genitalia morphology, supports the inclusion of J. pecki in the family Pyramidopidae. This represents the first record for the family Pyramidopidae in the New World, raising the question of whether this represents transoceanic dispersal or a relict of an ancient widespread tropical Gondwanan distribution.

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Section: Methodsmentioning

confidence: 99%

When troglomorphism dupes taxonomists: morphology and molecules reveal the first pyramidopid harvestman (Arachnida, Opiliones, Pyramidopidae) from the New World

2016

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“…The pedipalps of harvestmen can also be distinctly derived, as reflected by taxonomic names such as Nemastoma (‘thread mouth’) or Dicranopalpus (‘two‐headed palp’). They can be sexually dimorphic, with male pedipalps being elongated, thickened, or equipped with spines, in which case male polymorphism may also frequently occur (Buzatto & Machado, ). Dimorphism is related to mating, in which the pedipalp is used to grasp and secure the female at the front leg coxae (Willemart et al ., ; Burns, Hedin & Shultz, ).…”

Section: Introductionmentioning

confidence: 99%

The evolution of pedipalps and glandular hairs as predatory devices in harvestmen (Arachnida, Opiliones)

Wolff¹,

Schönhofer

Martens

et al. 2016

Zool J Linn Soc

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Pedipalps are the most versatile appendages of arachnids. They can be equipped with spines (Amblypygi), chelae (Scorpiones), or adhesive pads (Solifugae), all of which are modifications to grasp and handle fast-moving prey. Harvestmen (Opiliones) show a high diversity of pedipalpal morphologies. Some are obviously related to prey capture, like the enlargement and heavy spination of Laniatores pedipalps. Many Dyspnoi, by contrast, exhibit thin, thread-like pedipalps that are covered with complex glandular setae (clavate setae). These extrude viscoelastic glue that is used to immobilize prey items. Comparable setae (plumose setae) have previously been found in representatives of both Eupnoi and Dyspnoi, yet comprehensive data on their distribution are lacking. This study examined the distribution and ultrastructure of glandular setae in harvestmen and related them to pedipalpal morphology. Pedipalpal and setal characters were analysed in a phylogenetic framework. We found that glandular setae are synapomorphic for and widespread in the Palpatores clade (Eupnoi plus Dyspnoi). Their occurrence correlates with pedipalp morphology and feeding habit. Remnants of arthropod cuticular structures or secretions, frequently found attached to glandular setae, and behavioural observations, underlined the importance of the setae for capturing and securing prey. We hypothesize that glandular setae evolved as an adaptation to capture small and agile prey, which are hard to catch with a capture basket. Details of ultrastructure indicate that the setae are derived sensilla chaetica, with both a secretory and sensory function. Derived ultrastructural characters of the glandular setae, such as slit-like channel openings and a globular arrangement of the microtrichia, may increase their effectiveness. The functional role of further pedipalpal modifications, such as apophyses, stalked and hyperbendable joints, and curved segments, as well as sexual dimorphism and ontogenetic polymorphism, are discussed. Some implications of the results obtained for the taxonomic treatment of Phalangiidae are also discussed. These results shed new light on the biology and evolutionary history of this fascinating group of arthropods.

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“…The tarsi of the pedipalps of adult laniatorean harvestmen are adorned with robust claws in contrast to the distal surfaces of the tarsi of nymphs in some families (i.e., Cosmetidae) that feature weakly sclerotized pretarsi (Wolff et al, ). In laniatorean harvestmen, the morphology of the pedipalps may also exhibit sexual dimorphism, and, infrequently, male polymorphism (Buzatto & Machado, ; Wijnhoven, ).…”

Section: Introductionmentioning

confidence: 99%

“…The pedipalps of harvestmen are primarily used in prey capture and food manipulation, but may also function in courtship, defense, fighting, grooming, substrate attachment, and to gather sensory information (reviewed by Wolff et al, ). Pedipalps often exhibit sexual dimorphism, with males having larger podomeres that are equipped with more sensilla chaetica than females (Buzatto & Machado, ). The morphology of the pedipalps may also vary ontogenetically (reviewed by Wolff et al, ).…”

Section: Introductionmentioning

confidence: 99%

Ontogenetic variation in the sensory structures on the pedipalps of cosmetid harvestmen (Arachnida, Opiliones, Laniatores)

Townsend

Enzmann²

2017

Journal of Morphology

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In arachnids, pedipalps are highly variable appendages that may be used in feeding, courtship, defense, and agonistic encounters. In cosmetid harvestmen, adults have pedipalps that feature flattened femora, spoon-shaped tibiae, and robust tarsal claws. In contrast, the pedipalps of nymphs are elongate with cylindrical podomeres and are adorned with delicate pretarsi. In this study, we used scanning electron microscopy to examine the distribution of cuticular structures (e.g., sensilla chaetica, pores) on the elements of the pedipalps of adults and nymphs of three species of cosmetid harvestmen. Our results indicate that there is considerable ontogenetic variation in the morphology of the trochanter, femur, patella, tibia, and tarsus. The pretarsus of the nymph has a ventral patch of setae that is absent from the adult tarsal claw. We observed this structure on all three cosmetid species as well as on the pedipalps of an additional seven morphospecies of nymphs collected in Belize and Costa Rica. This structure may represent a previously unrecognized autapomorphy for Cosmetidae. Examinations of the pedipalps of antepenultimate nymphs of additional gonyleptoidean harvestmen representing the families Ampycidae, Cranaidae, Manaosbiidae, and Stygnidae revealed the occurrence of unusual, plumose tarsal setae, but no setal patches on the tarsal claw. K E Y W O R D Snymph, pretarsus, sensilla chaetica, tarsal claw

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Male dimorphism and alternative reproductive tactics in harvestmen (Arachnida: Opiliones)

Cited by 58 publications

References 106 publications

When troglomorphism dupes taxonomists: morphology and molecules reveal the first pyramidopid harvestman (Arachnida, Opiliones, Pyramidopidae) from the New World

When troglomorphism dupes taxonomists: morphology and molecules reveal the first pyramidopid harvestman (Arachnida, Opiliones, Pyramidopidae) from the New World

The evolution of pedipalps and glandular hairs as predatory devices in harvestmen (Arachnida, Opiliones)

Ontogenetic variation in the sensory structures on the pedipalps of cosmetid harvestmen (Arachnida, Opiliones, Laniatores)

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