Pseudovermis paradoxus 2.0—3D microanatomy and ultrastructure of a vermiform, meiofaunal nudibranch (Gastropoda, Heterobranchia)

Flammensbeck, Christina K.; Haszprunar, Gerhard; Korshunova, Tatiana; Martynov, Alexander; Neusser, Timea P.; Jörger, Katharina M.

doi:10.1007/s13127-018-0386-2

Cited by 4 publications

(6 citation statements)

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“…The facultative-burrowing adult Xenocratena, therefore, demonstrates early stages of paedomorphic evolution, whereas obligate infaunal Pseudovermidae instead demonstrate its 'terminal stages', when adult animals closely resemble early postlarval stages of other aeolidacean nudibranchs [22,80]. Well-established examples from groups of vertebrates show that an irreversible fixation of originally facultative/intraspecific paedomorphic traits [58] is part of the evolutionary process [81].…”

Section: Burrow-driven Evolution Results In Multiple Paedomorphic Linmentioning

confidence: 97%

“…Xenocratena has no more than eight ceratal rows ( Fig 3A and 3B, indicated by arrows), whereas Murmania possesses more than 40 (Fig 3D). Because during ontogeny of nudibranchs the number of ceratal rows gradually increases [79,80], and because the common ancestor of all aeolidacean possessed a large number of ceratal rows [19] it then follows that the small number of ceratal rows in Xenocratena only corresponds to juvenile stages of a common ancestor of the clade (Figs 1 and 4) consisting of the small Xenocratena (commonly less than 10 mm, maximum 12 mm adult length) and large Murmaniidae (up to 46 mm adult length). Basal members of the unrelated aeolidacean families Aeolidiidae and Paracoryphellidae are also large-sized (adults up to 50 mm or more) with numerous ceratal rows and demonstrate considerable external similarities to the complex Murmaniidae [19].…”

Section: Burrow-driven Evolution Results In Multiple Paedomorphic Linmentioning

confidence: 99%

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Multiple paedomorphic lineages of soft-substrate burrowing invertebrates: parallels in the origin of Xenocratena and Xenoturbella

et al. 2020

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Section: Burrow-driven Evolution Results In Multiple Paedomorphic Linmentioning

confidence: 97%

Section: Burrow-driven Evolution Results In Multiple Paedomorphic Linmentioning

confidence: 99%

Multiple paedomorphic lineages of soft-substrate burrowing invertebrates: parallels in the origin of Xenocratena and Xenoturbella

et al. 2020

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“…The diversity of cnidosac morphology, while being quite conservative in its general structure, represents a high level of variability in specific details. Full descriptions of cnidosacs structure are quite rare (Goodheart et al, 2018), however, for several “model” species suitably detailed descriptions exist, that is, Spurilla neapolitana (Conklin & Mariscal, 1977; Greenwood & Mariscal, 1984), Aeolidia papillosa and Aeolidiella soemmeringi (Kälker & Schmekel, 1976), all—Aeolidiidae; Cratena peregrina , Facelinidae (Martin, 2003); Pseudovermis , Pseudovermidae (Jörger et al, 2014; Flammensbeck et al, 2019); Flabellina affinis (Martin et al, 2009) and Flabellinopsis pedata (Kälker & Schmekel, 1976), both Flabellinidae s.l . ; Embletonia pulchra , Embletoniidae (Martin et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

General and fine structure of Aeolidia papillosa cnidosacs (Gastropoda: Nudibranchia)

Vorobyeva

Малахов

Ekimova

2021

Journal of Morphology

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Nudibranch mollusks (Gastropoda: Heterobranchia) are widely known for their ability to incorporate some active biochemical compounds of their prey, or even organelles and symbionts of the prey, which assured biological success of this group. At the same time, the process of nematocysts obtaining and incorporation into specific structures called cnidosacs by cladobranch mollusks remain poorly studied. This highlights a necessity of additional ultrastructural studies of cnidosac and adjacent organs in various aeolid mollusks using modern microscopic methods as they may provide new insight into the cnidosac diversity and fine‐scale dynamics of nematocysts sequestration process. The present study is focused on the general and fine structure of the cnidosac area in cladobranch Aeolidia papillosa (Aeolidiidae). Specific goals of our study were to provide a detailed description of histological and ultrafine structure of epidermis, upper parts of the digestive glands and the cnidosac, its innervation and proliferation using standard histological techniques, confocal laser scanning microscopy (CLSM) and transmission electron microscopy. Our results clearly demonstrated that A. papillosa cnidosac is a much more complex structure, than it was thought, especially compared with simple cnidosacs found in flabellinids and facelinids. Using CLSM for functional morphological analysis provides a better resolution in visualization of structural elements within a cnidosac compared with traditional histological techniques. We revealed the presence of two cell types in the cnidophage zone: cnidophages and interstitial cells, which differ in ultrastructure and function. Our results also document the presence of a specific cnidopore zone, lined with differentiated cuboid epithelium bearing long microvilli, which likely provides a unidirectional flow of nematocysts during kleptocnides extrusion. For the first time, occurrence of vacuoles containing protective chitinous spindles in the cnidosac epithelium was shown.

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“…Sponges carry nk gene families from the large antp homeobox class, although definite cnidarian and bilaterian homeobox gene families such as Hox are absent (Holland, 2013;Fortunato et al, 2014;Pastrana et al, 2019). However, sponges also have the specific Wnt-signaling pathway, typical for all Bilateria (Holstein, 2012), and demonstrate other complicated bilaterian-like genomic features (Voigt et al, 2014).…”

Section: Developmental and Molecular Pathways Support Poriferan Seden...mentioning

confidence: 99%

“…To summarize the recent data, sedentary sponges have the Wnt-signaling pathway, but not the true Hox genes (Fortunato et al, 2014;Pastrana et al, 2019). Placozoans are motile, possess a Wnt and a Trox gene, but lack true Hox genes (Jakob et al, 2004).…”

Section: Developmental and Molecular Pathways Support Poriferan Seden...mentioning

confidence: 99%

Renewed perspectives on the sedentary-pelagic last common bilaterian ancestor

Martynov

Korshunova

2022

Contrib. Zool.

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Various evaluations of the last common bilaterian ancestor (lcba) currently suggest that it resembled either a microscopic, non-segmented motile adult; or, on the contrary, a complex segmented adult motile urbilaterian. These fundamental inconsistencies remain largely unexplained. A majority of multidisciplinary data regarding sedentary adult ancestral bilaterian organization is overlooked. The sedentary-pelagic model is supported now by a number of novel developmental, paleontological and molecular phylogenetic data: (1) data in support of sedentary sponges, in the adult stage, as sister to all other Metazoa; (2) a similarity of molecular developmental pathways in both adults and larvae across sedentary sponges, cnidarians, and bilaterians; (3) a cnidarian-bilaterian relationship, including a unique sharing of a bona fide Hox-gene cluster, of which the evolutionary appearance does not connect directly to a bilaterian motile organization; (4) the presence of sedentary and tube-dwelling representatives of the main bilaterian clades in the early Cambrian; (5) an absence of definite taxonomic attribution of Ediacaran taxa reconstructed as motile to any true bilaterian phyla; (6) a similarity of tube morphology (and the clear presence of a protoconch-like apical structure of the Ediacaran sedentary Cloudinidae) among shells of the early Cambrian, and later true bilaterians, such as semi-sedentary hyoliths and motile molluscs; (7) recent data that provide growing evidence for a complex urbilaterian, despite a continuous molecular phylogenetic controversy. The present review compares the main existing models and reconciles the sedentary model of an urbilaterian and the model of a larva-like lcba with a unified sedentary(adult)-pelagic(larva) model of the lcba.

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Pseudovermis paradoxus 2.0—3D microanatomy and ultrastructure of a vermiform, meiofaunal nudibranch (Gastropoda, Heterobranchia)

Cited by 4 publications

References 63 publications

Multiple paedomorphic lineages of soft-substrate burrowing invertebrates: parallels in the origin of Xenocratena and Xenoturbella

Multiple paedomorphic lineages of soft-substrate burrowing invertebrates: parallels in the origin of Xenocratena and Xenoturbella

General and fine structure of Aeolidia papillosa cnidosacs (Gastropoda: Nudibranchia)

Renewed perspectives on the sedentary-pelagic last common bilaterian ancestor

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