Malakhov V.V.1, Kuzmina T.V.1, Madison A.A.2 2021. Classification of planktonic stages of extant brachiopods // Invertebrate Zoology. Vol.18. No.2: 95–104 [in English].
2 Borisyak Paleontological Institute, Russian Academy of Sciences, Profsoyuznaya ul. 123, Moscow, 117997 Russian Federation. E-mail: firstname.lastname@example.org
ABSTRACT: Brachiopods are characterized by a pelago-benthic life cycle and strongly differ in their planktonic stages. However, the planktonic stages in brachiopod ontogeny still do not have special names. Here we propose names for all planktonic stages of extant brachiopods. The chaetotrocha is a larva consisting of a round anterior lobe with a ciliary band and a body with three pairs of larval setae bundles. Lecithotrophic chaetotrocha is a larva of extant Craniiformea. The cephalula is a larva divided into the anterior lobe bearing the apical ciliary tuft and a marginal ciliary band, a mantle lobe with larval setal bundles, and a pedicle lobe. Lecithotrophic cephalula is the only larval stage of recent Rhynchonelliformea. The development of Discinidae includes three planktonic stages succeeding each other. The first is the cephalula. Second developmental stage of Discinidae is the chaetolopha with a rudimentary lophophore and larval spinose setae. The third stage of discinid development is the tegulolopha with a lophophore and a shell. The only planktonic stage of extant Lingulidae is the tegulolopha. Larvalization and embryonization are the main trends in the evolution of larval development of brachiopods.
KEY WORDS: Brachiopoda, larval development, chaetotrocha, cephalula, chaetolopha, tegulolopha, larvalization, embryonization.