Confocal microscopy reveals uniform male reproductive anatomy in eriophyoid mites (Acariformes, Eriophyoidea) including spermatophore pump and paired vasa deferentia

Abstract

Male internal genitalia of eriophyoid mites comprise cuticle lined (anterior genital apodeme, genital chamber and ductus ejculatorius) and soft (paired vasa deferentia and single testis) organs. Three-dimensional reconstructions based on autofluorescence show that a thin-walled genital chamber is usually situated in a transverse plane and precisely copies the shape of the spermatophore. A thin vertical longitudinal plate (homologous to female longitudinal bridge) joins the genital chamber and ventral genital cuticle. The anterior genital apodeme is a separate vertical plate situated ahead of the genital chamber and provides a rigid support for it. The brightly autofluorescent ductus ejaculatorius starts from the posterior extremity of the genital chamber and goes backward. Proximally, the ductus ejaculatorius is tube-like, whereas distally, it is expanded into a sac. Confocal laser scanning microscopy observations on males, stained with phalloidin, indicate that the proximal ductus ejaculatorius is devoid of muscles whereas the distal ductus ejaculatorius possesses well-developed musculature (the "spermatophore pump"), appearing in 3D reconstructions as a hollow sphere with three apertures: one anterior and two posterior. Two thin-walled sausage-like vasa deferentia join the distal ductus ejaculatorius with a large single testis, each junction is encircled by a strong, ring-shaped muscle (musculus sphincter testiculodeferentis). Thin muscular fibers of the wall of the testis form a net-like pattern consisting of distinct polygonal cells. The topography of the male internal genitalia and musculature suggests that, contrary to previous observations, the spermatophore head might be extruded first and then the spermatophore stalk appears. The possible role of visceral and skeletal musculature, in the process of the expulsion of a spermatophore, is discussed.

A gall mite,Aceria rhodiolae(Acari: Eriophyidae), altering the phytochemistry of a medicinal plant,Rhodiola rosea(Crassulaceae), in the Canadian Arctic

“…Other measurements that may need clarification are: ventral opisthosomal annuli were counted from the posterolateral corner of coxal field II; length of prodorsal shield includes the frontal lobe; the position of some leg setae (bv, l', l") were measured from the proximal margin of the segment bearing the seta; the number of microtubercles between setae sc are counted as the microtubercles on the first complete annulus (the first one is often incomplete) behind the prodorsal shield; the number of microtubercles between pairs of setae c2, d, e and f are counted ventrally. Internal genitalia were essentially described using the morphometrics proposed by Chetverikov et al (2012Chetverikov et al ( , 2013 based on DIC light microscopy, and further interpreted using Chetverikov (2014) for females, and Chetverikov (2015) for males. Because specimens from Italy (see 'Material examined') were in poor shape (body twisted or deformed, and some setae cut or only partly discernible), the length of leg setae and the distance between opisthosomal setae for those specimens were considered unreliable and were excluded.…”

“…Epiandrium 22-24 wide, 14.5-15.3 long, including the region of irregularly scattered, rounded microtubercles between setae 3a (Figure 6B); eugenital setae c. 1 μm long, bases 3.0-3.5 apart. Internal structures identified include anterior genital apodeme ('aga'), genital chamber ('ch'), proximal and distal ejaculatory ducts (the latter acting as a spermatophore pump), both highly sclerotized (based on their high autofluorescence under CLSM), connected posteriorly to a pair of vasa deferentia ('vd'), leading to a putative testis (Chetverikov 2015).…”

Size, shape, and direction matters: Matching secondary genital structures in male and female mites using multiple microscopy techniques and 3D modeling

“…Confocal Laser Scanning Microscopy (CLSM) is a technique that cannot match the resolution of TEM, but it is fast, non-destructive, can be applied to fluid and slide preserved specimens, and can help reveal 3-dimensional internal and external structures. Our initial assumption, based on previous studies done in mites of the superorder Acariformes [18][19][20][21][22][23][24][25][26], was that CLMS would be a successful technique for external and internal morphology, even though mesostigmatid mites have a thicker and more sclerotized cuticle than most Acariformes [27].…”