Morphology and evolution of scopula, pseudoscopula and claw tufts in Mygalomorphae (Araneae)

Abstract

We studied the morphology of scopula, claw tufts and a scopula-like feature (pseudoscopula) of tarsi on representatives of all Mygalomorphae spider families. The pseudoscopula is constituted by groups of non-microtriched conical setae. The taxonomic distribution of all these features was studied and mapped on a recent phylogeny of Mygalomorphae and the association of them with the lifestyles of the spiders was analyzed. Adhesive setae, as well as some other setal types found on ventral tarsi are described and characterized. The adhesive face of setae varied in the orientation in different parts of the tarsi, and this variation is more conspicuous in the spiders which only have claw tufts or scopula. We found an association of adhesive scopulae and claw tufts with burrower/cursorial or thin wafer lid trapdoor mygalomorphs as suggested for free hunter spiders, but we found that the pseudoscopula is associated with males of some trap-door and some weavers mygalomorphs. The presence of pseudoscopula widely extended among Mygalomorphae seems to be ancestral for the infraorder. The setal morphology of pseudoscopula suggests chemosensorial function; sparse chemosensory setae were also found in almost all Mygalomorphae. The morphology, functions and evolution of scopula, claw tufts and pseudoscopula are discussed.

Total‐evidence analysis of an undescribed fauna: resolving the evolution and classification of Australia’s golden trapdoor spiders (Idiopidae: Arbanitinae: Euoplini)

“…Changes to this character occurred between clades, species‐groups, and even sister‐species. Pérez‐Miles et al (2017) recently suggested that these scopulae (called pseudoscopula in his study) may play a role during copulation. This may explain the similar evolutionary pattern (i.e.…”

“…frequent state changes at shallow phylogenetic levels) seen in these scopulae relative to the sexual characters of males. However, Pérez‐Miles et al (2017) also suggested that the role of these scopulae may be to stabilize the male while his anterior legs (I–II) are engaged with the female, in which case one might expect this character to be conserved at lower phylogenetic levels. In future, copulation experiments between sister species in Cryptoforis which differ in the presence/absence of these scopulae (such as between 7 C. tasmanica and 8 C. “SpurrsRivulet” or 9 C. “Launceston”; or between 11 C. “TapinTops” and 12 C. “MountBoss”) could help to shed light on their function and explain their variability.…”

Shifting evolutionary sands: transcriptome characterization of the Aptostichus atomarius species complex

“…They present several challenges to researchers interested in performing rigorous experimental studies; they can be difficult to collect in large numbers from across their ranges, they are remarkably long-lived and take years to reach sexual maturity [3,4], and, until recently, very few genetic markers and no genomic resources were available for the infraorder (but see [5,6]). At the same time, they pose considerable appeal in terms of investigating physiological adaptation to harsh environments [7], longevity [8], evolution and application of novel venom peptides [9], chemosensory systems [10], genome size evolution [11], and historical biogeography, to name a few. With technological advances in sequencing, opportunities to begin generating genomic resources for nonmodel arthropods have increased substantially, from only three genomes in 2002 to over 540 at varying levels of completeness (27 at the chromosome level, 63 at the contig level, 458 at the scaffold level [12]).…”

Kinematics of maleEupalaestrus weijenberghi(Araneae, Theraphosidae) locomotion on different substrates and inclines

“…These structures could play an important role in locomotion, both on level ground and while climbing (Niederegger & Gorb, 2006; Foelix, 2011; Spagna & Peattie, 2012; Wolff, Nentwig & Gorb, 2013; Wohlfart et al, 2014; Lapinski, Walther & Tschapka, 2015; Pérez-Miles, Perafán & Santamaría, 2015; Wolff & Gorb, 2015; Pérez-Miles et al, 2017). Most of the species of Mygalomorphae (72%) have adhesive setae and they usually display cursorial lifestyles (Wolff, Nentwig & Gorb, 2013; Pérez-Miles et al, 2017). However, the contribution of these features with respect to climbing is subject to controversy (Pérez-Miles, Perafán & Santamaría, 2015; Pérez-Miles et al, 2017).…”

“…Most of the species of Mygalomorphae (72%) have adhesive setae and they usually display cursorial lifestyles (Wolff, Nentwig & Gorb, 2013; Pérez-Miles et al, 2017). However, the contribution of these features with respect to climbing is subject to controversy (Pérez-Miles, Perafán & Santamaría, 2015; Pérez-Miles et al, 2017). Pérez-Miles, Perafán & Santamaría (2015) analyzed the role of the adhesive setae of different species to improve locomotion on level ground and at different gradients of incline using both glass and Teflon as substrate for their trials.…”