Elemental characterization of the exoskeleton in the whipscorpions Mastigoproctus giganteus and Typopeltis dalyi (Arachnida: Thelyphonida)

Abstract

The arthropod cuticle is a structurally diverse secretion that is largely composed of lipids, proteins, and α‐chitin that function together in protection, prey capture, and as a skeletal framework for efficient and diverse means of locomotion. Aquatic, aerial, and terrestrial arthropods are well known to enrich their cuticles with trace elements that are proposed to strengthen or otherwise enhance specific regions of the exoskeleton. In this study, we provide evidence that whipscorpions (vinegaroons) enrich their exoskeleton with up to 14 trace elements. We use energy‐dispersive x‐ray spectroscopy (EDS) to provide the first comparisons of trace element composition in two species of Thelyphonida: Mastigoproctus giganteus (female) and Typopeltis dalyi (female and male). We analyzed the chemical composition of eight regions that have sensory, locomotory, taxonomic, protective, and/or predatory significance: the flagellum, prosoma, tarsal claws of the walking legs, tarsi of the antenniform legs, chelicerae, and the terminal three segments of the pedipalps. Our results reveal the presence of 14 trace elements across both species (12 elements in T. dalyi, 10 elements in M. giganteus), and only four elements are present at significant levels (≥1% weight): Si, Cl, Ca, and Zn. The flagellum, antenniform leg tarsi, and prosoma keel lack these elements in both species, while the chelicerae of all species are enriched with Ca, Zn, and Cl, and the tarsal claws are enriched with Zn. Significantly, we note the presence of Si in the prosomal carapace (but not the keel) of males and females of Typopeltis only, which appears to be the first evidence of this transition metal in the arthropod exoskeleton. We discuss the significance of these chemical enrichments in whipscorpions and provide hypotheses about their functional significance.

Anaplasma pathogen infection alters chemical composition of the exoskeleton of hard ticks (Acari: Ixodidae)

“…Although at least part of the Al may be a contamination from the aluminum scanning electron microscope stubs, herein we provided the first evidence for the presence of the post-transition metal Al in tick exoskeleton. As found here in ticks, the presence of certain elements such as Si is rare in arthropod exoskeleton [6] .…”

“…The exoskeleton is a structure that protects arthropods from natural threats such as predators and diseases. In ticks as in other terrestrial arthropods, the relative amount of chitin fibrils and protein matrix, protein composition, pH/water content of the matrix, composition of chemical elements and cross-linking of the matrix protein affect the properties of the exoskeleton [3] , [4] , [5] , [6] , [7] . It has been shown that mechanical properties of tick cuticle change during tick feeding to support the increase in body size and mass during this process [3] .…”

Tick and Host Derived Compounds Detected in the Cement Complex Substance

“…Increased levels of NADPH in ticks have been associated with response to Anaplasma phagocytophilum pathogen infection and tolerance to oxidative stress [61,62]. The source of other chemical elements such as Na, K, Cl, and P, which may contribute to cement biomineralization and coating [29,63] probably come from environmental sources (e.g., water, air, and soil).…”

Targeting the Exoskeleton Elementome to Track Tick Geographic Origins

“…In ticks, as in other terrestrial arthropods, the relative amount of chitin fibrils and protein matrix, protein composition, pH/water content of the matrix, composition of chemical elements, and cross-linking of the matrix protein affect the properties of the exoskeleton (Cribb et al, 2010;Flynn and Kaufman, 2015;Gallant et al, 2016;Gallant and Hochberg, 2017;Suppan et al, 2018). It has been shown that mechanical properties of tick cuticle change during tick feeding to support the increase in body size and mass during this process (Flynn and Kaufman, 2015).…”