Vakhrushev A.E.1, Temereva E.N.2* 2025. New data on early astogeny and microstructure of cystid in Patinella verrucaria (Bryozoa: Cyclostomata) // Invert. Zool. Vol.22. No.4. P.595–613 [in English].
1 Invertebrate Zoology Department, Lomonosov Moscow State University, Leninskie Gory 1-12, Moscow 119234 Russia.
2 Evolutionary Biology Department, Lomonosov Moscow State University, Leninskie Gory 1-12, Moscow 119234 Russia.
*Corresponding author
Elena Temereva: temereva@mail.ru ORCID https://orcid.org/0000-0001-7791-0553
Alexey Vakhrushev: a.e.vakhr@gmail.com ORCID https://orcid.org/0009-0003-9622-9212
doi: 10.15298/invertzool.22.4.06
ABSTRACT: Cyclostomatida is one of two groups of recent bryozoans with a skeleton of calcium carbonate. Unlike Cheilostomatida, the skeleton of cyclostome bryozoans has a small set of characters that can be used for identification and phylogenetic analysis. In this study, we used computed microtomography (mCT) and scanning electron microscopy (SEM) to deepen our understanding of the early stages of development and microstructural characteristics of representatives of the Lichenoporidae family using Patinella verrucaria as an example. The outer wall of the colony has a granular microstructure and is covered with a cuticle. In the inner colony walls, we registered three zones composed of only two fabrics: the accretion zone (with a granular fabric), the transition zone, and the zone of foliaceous crystallites (both with a foliated fabric). The inner wall of the colony has numerous outgrowths, or pustules, arranged in rows along the growing edge of the colony. They reach their maximum size at a certain distance from the colony centre and can be involved in the transport of materials within the colony. The process of skeletal formation in P. verrucaria is similar to that of other cyclostome bryozoans and resembles the process of biomineralization observed in Mollusca. Microscopic skeletal features are important identification characters at both the genus and species levels and also can be used to identify growth zones within a colony. Our data on the skeletal microstructure of the alveoli suggest that they are kenozooids. The study of young colony development using light microscopy and, for the first time, mCT confirmed two options of colony development relative to the growth direction of the first zooid: right- and left-directional scenarios. This phenomenon exemplifies the enantiomorphic colonies recorded in recent cyclostomes. The two mirror types of early colony development have a ratio of 470 (right):394 (left), suggesting either a genetic determination of growth or a significant influence of the physical characteristics of the substrate on colony development.
KEY WORDS: colony development, computer microtomography, scanning electron microscopy, enantiomorphy, symmetry features, Lichenoporidae, White Sea.