Sperm structure and phylogeny of Astigmata

Abstract

The Astigmata, a large and variable group, is still a subject of taxonomic dispute. Particularly, their origin from ancestors of the lower oribatid mites (e.g., Malaconothroidea) seems well documented by many lines of evidence. The structure of spermatozoa has been successfully applied to phylogenetic investigations in many animal groups. The aim of our study was to provide new data on spermatozoon structure in Astigmata and to consider its appropriateness in phylogenetic studies. The study reveals information on spermatozoa in 17 species of Astigmata (11 species studied for the first time) extending our knowledge to 18 species (one species known only from the literature) representing 12 families and 7 superfamilies. Spermatozoa have the same basic structure in all species: cells are multiform and the chromatin forms thin threads embedded directly in the cytoplasm; the acrosome is absent. The cytoplasm in most species contains electron-dense lamellae, varying in both number and arrangement within the cell. In Sarcoptoidea, electron-dense tubules in contact with lamellae margins were also observed in Psoroptidae (Psoroptes equi), whereas in two representatives of Sarcoptidae (Notoedres cati and Sarcoptes scabiei), only electron-dense tubules were found. In two species, Canestrinia sellnicki (Canestrinioidea: Canestriniidae) and Scutulanyssus obscurus (Analgoidea: Pteronyssidae), neither lamellae nor tubules were present. The mitochondria in a spermatozoon are usually gathered at the cell periphery and their structure is usually modified to form so-called mitochondrial derivatives. The chromatin threads are an autapomorphy strongly supporting the monophyly of Astigmata. As spermatozoa vary considerably between species in Astigmata, we deduce that sperm structure may be useful for phylogenetic analyses within the group. Several conclusions concerning the affinities within Astigmata are presented. Spermatology seems to be unhelpful, however, in questions on the origin of Astigmata (particularly for Astigmata-Oribatida relationships), since their sperm do not possess synapomorphies with sperm of the remaining groups of Acariformes, i.e., Endeostigmata, Prostigmata, and Oribatida.

Dog sperm swimming parameters analysed by computer‐assisted semen analysis of motility reveal major breed differences

“…There are significant variations in both morphometric (Roldan, Gomendio, & Vitullo, ; Soler et al, ; Soler, Sancho et al, ; Tourmente et al, ) and kinematics parameters of spermatozoa (Fitzpatrick et al, ; Tourmente et al, ). In recent decades, sperm characteristics have been successfully used for taxonomic studies in many animal groups including annelids (Ferraguti & Erséus, ; Ferraguti, Erséus, Kaygorodova, & Martin, ), insects (Dias, Oliveira, & Lino‐Neto, ; Jamieson, ), crustaceans (Jamieson), arachnids (Liana & Witaliński, ), amphibians (Selmi, Brizzi, & Bigliardi, ), fishes (Jamieson), birds (Jamieson, ) and mammals (Roldan et al, ; Soler et al, ; Soler, García et al, ). However, it should be borne in mind that similarities have been found in sperm swimming kinematic patterns between distantly related organisms, which cannot be explained solely by phylogenetic relationships (Guasto, Burton, Zimmer, Hosoi, & Stocker, ).…”

“…In recent decades, sperm characteristics have been successfully used for taxonomic studies in many animal groups including annelids Ferraguti, Erséus, Kaygorodova, & Martin, 1999), insects (Dias, Oliveira, & Lino-Neto, 2013;Jamieson, 1987), crustaceans (Jamieson1991b), arachnids (Liana & Witaliński, 2005), amphibians (Selmi, Brizzi, & Bigliardi, 1997), fishes (Jamieson1991a), birds (Jamieson, 2007) and mammals (Roldan et al, 1992;. However, it should be borne in mind that similarities have been found in sperm swimming kinematic patterns between distantly related organisms, which cannot be explained solely by phylogenetic relationships (Guasto, Burton, Zimmer, Hosoi, & Stocker, 2013).…”

The phylogenetic relationship between Astigmata and Oribatida (Acari) as indicated by molecular markers

“…Only one of those was incongruent with the more general hypothesis of OConnor (1984) that Astigmata evolved within some non-basal clade of oribatid mites: Alberti (1991) noted that Astigmata sperm were unlike those of oribatid mites and similar in some ways to those of an endeostigmatid mite. However, Liana and Witalinski (2005) recently considered Astigmata spermatozoa to be so highly modiWed that their ultrastructure could not help in determining the external relationships of the group.…”

Comparative spermatology of selected polyclad flatworms (Platyhelminthes)

“…In recent years, sperm structure has been successfully applied to taxonomic considerations for many animal groups, e.g., annelids (Jamieson and Rouse, 1989;Ferraguti and Erséus, 1999;, insects, and other arthropods (Alberti and Weinmann, 1985;Jamieson, 1987Jamieson, , 1991bLiana and Witaliń ski, 2005), fish and tetrapods (Jamieson, 1991a(Jamieson, , 1995. Studies of the ultrastructure of sperm and spermatogenesis in Platyhelminthes showed that in this group, spermatozoa also carry strong phylogenetic information and can be useful in establishing a taxonomic system (Hendelberg, 1965(Hendelberg, , 1969(Hendelberg, , 1974(Hendelberg, , 1977(Hendelberg, , 1983(Hendelberg, , 1986Ehlers, 1985;Justine, 1995Justine, , 2001Bâ and Marchand, 1995;Watson and Rohde, 1995;Watson, 1999).…”