Fine structure and functional morphology of the mouthparts of a maleVeigaia sp. (Gamasida: Veigaiidae) with remarks on the spermatodactyl and related sensory structures

Abstract

Mites of the genus Veigaia are common gamasid inhabitants of forest litter. They engage in the peculiar reproductive strategy of podospermy which, along with other morphological and behavioral adaptations, involves modification of the chelicerae of the relatively rare males into gonopods. Each movable digit is provided with an appendage (spermatodactyl) that is involved in sperm transfer. We describe the gross anatomy, fine structure, and functional morphology of the mouthparts of a male Veigaia species and give ultrastructural details for the corniculi, laciniae, preoral cavity, labrum, pharynx, and movable and fixed digits. The fine structure of the spermatodactyl is illustrated here for the first time in detail. A semischematic reconstruction of the gnathosoma and spermatodactyl is provided. The spermatodactyl is totally fused with the movable digit and a sperm transfer duct runs along its entire length. This duct starts at the adaxial base of the movable digit, continues inside the digit into the tube of the spermatodactyl, and finally opens at the distal abaxial surface of the spermatodactyl. Several sensory structures associated with the spermatodactyl probably provide the male with mechanical and chemical clues.

Gross morphology, histology, and ultrastructure of the alimentary system of Ricinulei (Arachnida) with emphasis on functional and phylogenetic implications

“…2H,I). Lateral and ventral pharynx dilator muscles, like those found in other arachnids (e.g., Snodgrass1948; Evans, 1982; Alberti and Coons,1999; Weygoldt,2000; De Lillo et al2001; Di Palma et al,2006; Klann and Alberti,2010) are not present in the investigated ricinuleids. Remarkably, pharynx constrictor muscles do also not occur in Ricinulei.…”

“…Remarkably, pharynx constrictor muscles do also not occur in Ricinulei. Such muscles are well known from other arachnids (e.g., Snodgrass1948; Evans,1992; Weygoldt,2000; De Lillo et al2001; Alberti et al,2003; Di Palma et al,2006; Klann and Alberti,2010). Therefore, it has to be supposed that the pharynx lumen of Ricinulei can only be constricted in combination of (1) relaxation of the pharynx dilator muscles and (2) hemolymph which is pressed into the anterior prosoma region.…”

Mites coexistent with neotropical hispine beetles in unfurled leaves ofHeliconia: a new genus and family of the Ascoidea (Acari: Mesostigmata: Gamasina)

“…Mesostigmatic mites are characterized by each chelicera generally moving independently, with projection caused by hydrostatic (haemolymphic) pressure exerted by dorsoventral muscles in the idiosoma, and retraction by muscles attached to the basal article that originate usually on the pronotal region of the idiosoma (Alberti and Coons 1999). However, in forms with elongate cheliceral shafts, as in some Uropodina and parasitic Dermanyssoidea, these muscles have their origin on the posterior region of the idiosomatic dorsum (Karg 1989;Evans 1992;Di Palma et al 2006), and this is likely the case in Antennocheles. Projection occurs by way of tubular channels within the cheliceral frame that contains the cheliceral sheaths and proximal segments of the chelicerae (Alberti and Coons 1999).…”

“…A few Journal of Natural History 1647 ultrastructural studies among unrelated mesostigmatic mites have shown innervation running through the corniculus to the apex, where there may be a barely discernible glandular opening with possibly chemosensitive function (Nuzzaci et al 1992;Di Palma et al 2006;Alberti 2008). On the other hand, a lyrifissure has been noted at the base of the rutellum in the oribatid mite Archegozetes sp.…”

Ultrastructure of the male genital tract, spermatogenesis and spermatozoa of hattena cometis domrow (Acari: Gamasida: Ameroseiidae)

“…Spermatophores are transferred to the female genital opening and spermatozoa have been observed in the hemocoel of the inseminated female (Alberti, ; Alberti et al, ). Finally, males belonging to Dermanyssina have modified chelicerae bearing a process on the movable digit, called the spermatodactyl, which forms a tube through which spermatozoa are injected into the sperm access system of the female (Dosse, ; Krantz and Wernz, ; Di Palma and Alberti, , Di Palma et al, , , ). Interestingly, spermatozoa of the few members of the group studied in this respect are again strikingly different, being produced through a less complex spermatogenesis showing various shapes but all possessing peripheral chambers, which are variously arranged.…”