Flagellar apparatus structure of choanocyte in Sycon sp. and its significance for phylogeny of Porifera

Kinetid structure in Choanocytes of Sponges (Heteroscleromorpha): Toward the ancestral Kinetid of Demospongiae

“…Two representatves of Verongimorpha have a centriole located at a sharp angle to the kinetosome (Gonobobleva and Maldonado, 2009;Maldonado, 2009). As a centriole is also presents in Calcarea (Pozdnyakov and Karpov, 2013) and Homoscleromorpha (Boury-Esnault et al, 1984), we can suggest that a centriole was lost in the ancestor of Heteroscleromorpha.…”

“…A proximal part of the central microtubules and a portion of the axoneme around them look a bit darker than the axoneme above and below this region ( Fig. 3C), giving an appearance of a dense zone, which characterizes the kinetid of some other sponges (Pozdnyakov and Karpov, 2013). Some unresolved structures are also present around and below the proximal ends of central tubules (Fig.…”

“…Morphological variations of these kinetid features have now been shown for eight species of sponges (Boury‐Esnault et al, ; Karpov and Efremova, ; Amano and Hori, ; Gonobobleva and Maldonado, ; Pozdnyakov and Karpov, ). In all these cases, variations in kinetid structure are congruent with the topology of modern molecular phylogenetic trees (Pozdnyakov and Karpov, ), therefore we suggest that the kinetid structure of choanocytes may be used as a phylogenetic marker in sponges. To confirm this suggestion we have extended our series of studies on kinetid reconstruction in sponge choanocytes to a phylogenetically important group, the Demospongiae: Halichondria sp.…”

“…The few available studies of choanocytes of Porifera show that the characters of their kinetids are rather specific for this group with respect to the flagellar transition zone and flagellar root organization (Boury‐Esnault et al, ; Karpov and Efremova, ; Amano and Hori, ; Gonobobleva and Maldonado, ; Maldonado, ; Pozdnyakov and Karpov, ). Choanocyte kinetids normally comprise a flagellar kinetosome and, in some investigated species, an orthogonal non‐flagellar kinetosome or centriole.…”

Kinetid structure in sponge choanocytes of Spongillida in the light of evolutionary relationships within Demospongiae

“…Determining the phylogenetic significance of additional morphological characters may be useful in this regard. Previously, we discussed the usability of the flagellar apparatus (kinetid) structure of choanocytes as a phylogenetic marker (Pozdnyakov & Karpov, 2013, 2015. We demonstrated that kinetid structure differs between representatives of different sponge orders and that there is agreement between the topology of the molecular phylogenetic tree of sponges and the positions of different choanocyte kinetid types on this tree.…”