TY - JOUR

T1 - Phenotypic masquerade: Polymorphism in the life cycle of the centrohelid heliozoan Raphidiophrys heterophryoidea (Haptista: Centroplasthelida)

AU - Drachko, Daria

AU - ShIshkin, Yegor

AU - Zlatogursky, Vasily V.

N1 - Publisher Copyright: © 2020 Elsevier GmbH

PY - 2020/4

Y1 - 2020/4

N2 - The life cycle of the centrohelid heliozoan Raphidiophrys heterophryoidea Zlatogursky, 2012 was studied with light and electron microscopy in clonal cultures from the type locality. The alternation of two types of trophozoites, having contrastingly different morphology, was observed. Type 1 trophozoites morphology matched the original description. Type 2 trophozoites tended to form colonies usually of 6–8 individuals, connected with cytoplasmic bridges and their cell size was noticeably bigger, namely 43−45 μm compared to 24.5 μm on average in type 1 trophozoites. Some colonies were forming stalks composed of three or four axopodia covered with scales. Spicules were lacking completely, while plate-scales differed from those of type 1 trophozoites: they had oblong-elliptical shape, larger (5.9–14.1 × 2.4–5.8 μm) size, non-branching septa always reaching scale centre, solid upper plate. The conspecificity of the two trophozoite types was confirmed with the comparison of SSU rDNA gene sequence data. Both types of trophozoites were capable of encystment and excysted individuals always were type 1 trophozoites. A new type of cyst-scales (cup-scales) was described. Transitions between cysts and the two trophozoites types were documented. The diagnosis of R. heterophryoidea was improved accordingly. The possible functions, driving forces, and taxonomic consequences of the polymorphism were discussed.

AB - The life cycle of the centrohelid heliozoan Raphidiophrys heterophryoidea Zlatogursky, 2012 was studied with light and electron microscopy in clonal cultures from the type locality. The alternation of two types of trophozoites, having contrastingly different morphology, was observed. Type 1 trophozoites morphology matched the original description. Type 2 trophozoites tended to form colonies usually of 6–8 individuals, connected with cytoplasmic bridges and their cell size was noticeably bigger, namely 43−45 μm compared to 24.5 μm on average in type 1 trophozoites. Some colonies were forming stalks composed of three or four axopodia covered with scales. Spicules were lacking completely, while plate-scales differed from those of type 1 trophozoites: they had oblong-elliptical shape, larger (5.9–14.1 × 2.4–5.8 μm) size, non-branching septa always reaching scale centre, solid upper plate. The conspecificity of the two trophozoite types was confirmed with the comparison of SSU rDNA gene sequence data. Both types of trophozoites were capable of encystment and excysted individuals always were type 1 trophozoites. A new type of cyst-scales (cup-scales) was described. Transitions between cysts and the two trophozoites types were documented. The diagnosis of R. heterophryoidea was improved accordingly. The possible functions, driving forces, and taxonomic consequences of the polymorphism were discussed.

KW - cell coverings

KW - Colonies

KW - Cysts

KW - heliozoa

KW - Scales

KW - Ultrastructure

KW - Heliozoa

KW - Cell coverings

UR - https://www.sciencedirect.com/science/article/abs/pii/S093247392030016X

UR - http://www.scopus.com/inward/record.url?scp=85079831493&partnerID=8YFLogxK

U2 - 10.1016/j.ejop.2020.125686

DO - 10.1016/j.ejop.2020.125686

M3 - Article

VL - 73

JO - European Journal of Protistology

JF - European Journal of Protistology

SN - 0932-4739

M1 - 125686

ER -