The role of the integument with respect to different modes of locomotion in the Nematalycidae (Endeostigmata)

Abstract

Previous research on the locomotion of the Nematalycidae has only been undertaken on Gordialycus, which is by far the most elongated genus of the family. Gordialycus is dependent on an unusual form of peristalsis to move around. It was not known whether the genera of Nematalycidae with shorter bodies also used this mode of locomotion. Our videographic recordings of Osperalycus did not reveal peristalsis. Instead, this mite appears to move around the mineral regolith via the expansion and constriction of the metapodosomal and genital region, allowing greater versatility in the way that the annular regions contract and extend. This type of locomotion would enable relatively short bodied nematalycids to anchor themselves into secure positions before extending their anterior regions through tight spaces. Low-temperature scanning electron micrographs show that the short bodied genera have integumental features that appear to be associated with this mode of locomotion. Peristalsis is almost certainly a more derived form of locomotion that is an adaptation to the unusually long body form of Gordialycus.Electronic supplementary materialThe online version of this article (doi:10.1007/s10493-014-9857-0) contains supplementary material, which is available to authorized users.

Origin and higher-level diversification of acariform mites – evidence from nuclear ribosomal genes, extensive taxon sampling, and secondary structure alignment

“…The problem here is the absence of unequivocal morphological apomorphies supporting either the clade including most Endeostigmata or Euacariformes. We found a single character in support to the Endeostigmata clade: Nematalycidae presents cuticle projections known as palettes, which are oriented so that their edges are perpendicular with respect to the surface annuli, aiding in the grip of the body against the interstitial surface [ 61 ]. These palettes have also been found in the Nanorchestidae [ 62 ] where their function is uncertain, and some superficially similar structures may be seen in Bimichaelia (Alycidae) (SEM pictures in [ 63 ]).…”

A novel fluid-feeding mechanism for microbivory in the Acariformes (Arachnida: Acari)

“…However, live specimens of Osperalycus tenerphagus Bolton & Klompen were collected and mounted for LT-SEM by directly removing them from floated material that had not yet been sieved. This was accomplished by placing the floated material directly under a dissection microscope (see also Bolton et al, 2015).…”

“…Like other nematalycids, Osperalycus and Gordialycus appear to live exclusively in mineral soils or sands. Their unusual integumental morphology is clearly well adapted for moving around in these habitats (Bolton et al, 2015). Gordialycus is frequently found in deserts, beaches and sand dunes (see appendix; Coineau et al, 1967;Silva et al, 1989;Norton et al, 2008).…”

Morphological support for a clade comprising two vermiform mite lineages: Eriophyoidea (Acariformes) and Nematalycidae (Acariformes)

“…But if Nematalycidae are paraphyletic, they would have to be older than the Eriophyoidea, which originated no later than the Triassic (c. 230 Ma) (Schmidt et al 2012;Sidorchuk et al 2015). Accordingly, the highly elongated body and unusual modes of locomotion (Bolton et al 2015b) of Nematalycidae would represent a relatively early departure from the primitive body form and mode of locomotion of Acariformes.…”

“…By comparison, in Trombidiformes the movable digits of the chelicerae appear to have sunken into a preoral groove in the subcapitulum (de Lillo et al 2001;di Palma et al 2009); membranous extensions have not been observed. Eriophyoidea and Nematalycidae also share another unusual feature: they have anal valves (modified into lobes in Eriophyoidea) that are used to anchor the idiosoma in place (Baker et al 1987;Lindquist 1996b;Bolton et al 2015b).…”