Antonovskaya K.A.1,2, Neretina A.N.2, Voronezhskaya E.E.3, Kotov A.A.2* 2026. Appearance of muscle elements in the embryogenesis of Anomopoda and Ctenopoda (Crustacea: Branchiopoda: Cladocera) // Invert. Zool. Vol.23. No.3: 423–445 [in English].
1 Faculty of Biology, Lomonosov Moscow State University, Leninskie Gory 1-12, Moscow 119234 Russia.
2 A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Leninsky Prospect 33, Moscow 119071 Russia.
3 Koltsov Institute of Developmental Biology, Russian Academy of Sciences, Vavilova str. 26-1, Moscow 119334 Russia.
* Corresponding author: alexey-a-kotov@yandex.ru
Ksenia Antonovskaya: antonovskaya.kn@gmail.com ORCID https://orcid.org/0000-0002-2223-8947
Anna Neretina: neretina-anna@yandex.ru ORCID https://orcid.org/0000-0002-6876-079X
Elena Voronezhskaya: lenavor@gmail.com ORCID https://orcid.org/0000-0002-9953-2538
Alexey Kotov: alexey-a-kotov@yandex.ru ORCID https://orcid.org/0000-0002-8863-6438
doi: 10.15298/invertzool.23.3.05
ABSTRACT: Despite employing modern genetic approaches, the phylogenetic relationships between recent orders of the Cladocera (Crustacea: Branchiopoda) remain unclear. Reconstructions of phylogenetic relationships within the class Branchiopoda (containing both cladocerans and large branchiopods) based only on morphological features are vulnerable for criticism. Therefore the incorporation of data on anatomical changes during embryonic development in the phylogenetic analysis looks extremely promising. In this article, we present data on muscle development in Cladocera obtained via confocal laser scanning microscopy. We developed an original technique for labeling the musculature and embryo nuclei in two model species, Daphnia magna Straus, 1820 (Anomopoda) and Sida crystallina (O.F. Müller, 1776) (Ctenopoda), using phalloidin and methyl green. Periodization of musculature development according to the key events of embryogenesis was carried out using D. magna as a model. The general order of muscle formation in D. magna and S. crystallina is found to be similar. However, musculature of thoracic limbs, dorsoventral and oblique lateral muscles in S. crystallina have more pronounced metameric structure as compared to D. magna. Presence of traces of segmentation posteriorly to the fifth pair of thoracic limbs and sixth pair of dorsoventral muscles in ventral muscle band in D. magna can be interpreted as a rudiment of the sixth segment and sixth pair of thoracic limbs, which, however, are not visible as any, even minute, rudiments during embryogenesis. As compared to Cyclestheria hislopi Baird, 1859 (order Cyclestherida, a sister group of the cladocerans), the muscles of swimming antennae and thoracic limbs in D. magna and S. crystallina are more oligomerized. Specific traits of the musculature development have a phylogenetic signal on order level and can be used to reconstruct phylogenetic relationships within the class Branchiopoda.
KEY WORDS: Cladocera, Branchiopoda, anatomy, muscles, ontogeny, phylogenetic relationships, evolution.