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Schwaha T, Decker SH, Baranyi C, Saadi AJ. Rediscovering the unusual, solitary bryozoan Monobryozoon ambulans Remane, 1936: first molecular and new morphological data clarify its phylogenetic position. Front Zool 2024; 21:5. [PMID: 38443908 PMCID: PMC10913646 DOI: 10.1186/s12983-024-00527-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 02/26/2024] [Indexed: 03/07/2024] Open
Abstract
BACKGROUND One of the most peculiar groups of the mostly colonial phylum Bryozoa is the taxon Monobryozoon, whose name already implies non-colonial members of the phylum. Its peculiarity and highly unusual lifestyle as a meiobenthic clade living on sand grains has fascinated many biologists. In particular its systematic relationship to other bryozoans remains a mystery. Despite numerous searches for M. ambulans in its type locality Helgoland, a locality with a long-lasting marine station and tradition of numerous courses and workshops, it has never been reencountered until today. Here we report the first observations of this almost mythical species, Monobryozoon ambulans. RESULTS For the first time since 1938, we present new modern, morphological analyses of this species as well as the first ever molecular data. Our detailed morphological analysis confirms most previous descriptions, but also ascertains the presence of special ambulatory polymorphic zooids. We consider these as bud anlagen that ultimately consecutively separate from the animal rendering it pseudo-colonial. The remaining morphological data show strong ties to alcyonidioidean ctenostome bryozoans. Our morphological data is in accordance with the phylogenomic analysis, which clusters it with species of Alcyonidium as a sister group to multiporate ctenostomes. Divergence time estimation and ancestral state reconstruction recover the solitary state of M. ambulans as a derived character that probably evolved in the Late Cretaceous. In this study, we also provide the entire mitogenome of M. ambulans, which-despite the momentary lack of comparable data-provides important data of a unique and rare species for comparative aspects in the future. CONCLUSIONS We were able to provide first sequence data and modern morphological data for the unique bryozoan, M. ambulans, which are both supporting an alcyonidioidean relationship within ctenostome bryozoans.
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Affiliation(s)
- Thomas Schwaha
- Department of Evolutionary Biology, University of Vienna, Schlachthausgasse 43, 1030, Vienna, Austria.
| | - Sebastian H Decker
- Department of Evolutionary Biology, University of Vienna, Schlachthausgasse 43, 1030, Vienna, Austria
| | - Christian Baranyi
- Department of Evolutionary Biology, University of Vienna, Schlachthausgasse 43, 1030, Vienna, Austria
| | - Ahmed J Saadi
- Department of Evolutionary Biology, University of Vienna, Schlachthausgasse 43, 1030, Vienna, Austria
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Schwaha T, Gordon DP. Deep-sea ctenostome bryozoans: revision of the family Pachyzoidae, with description of a new genus and three new species from Zealandia. ZOOLOGICAL LETTERS 2024; 10:4. [PMID: 38321566 DOI: 10.1186/s40851-024-00226-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 01/04/2024] [Indexed: 02/08/2024]
Abstract
Pachyzoidae is a little-known family of deep-sea ctenostome Bryozoa that until now was monospecific for Pachyzoon atlanticum. Originally described from the Atlantic Ocean, the genus was also found off southeastern New Caledonia in deep waters of the geological continent of Zealandia. Pachyzoon atlanticum forms globular to flat round colonies, living on soft, muddy to sandy bottoms with a few rhizoidal cystid appendages extending from the basal, substrate-oriented side. In this study, we investigate additional pachyzoids, collected between 1965 and 2015 from over 40 sites around New Zealand, by means of detailed morphological and histological investigations. In total, several hundred colonies were encountered in the NIWA Invertebrate Collection, comprising two new species of the genus Pachyzoon, P. grischenkoi sp. nov. and P. pulvinaris sp. nov., and the new genus and species Jeanloupia zealandica gen. et sp. nov.. The genus Jeanloupia is characterized by small disc-shaped colonies with highly elongated peristomes and a quadrangular aperture, distinct from the round apertures of the genus Pachyzoon. Pachyzoid species differ in colony structure and shape, apertural papillae and polypide features such as tentacle number or digestive-tract details. Cystid appendages are non-kenozooidal, but may originate from laterally flanking kenozooids. Based on published images, alleged P. atlanticum from New Caledonia is re-interpreted as P. pulvinaris n. sp.. Morphological characters support alcyonidioidean relationships, as previously suggested. First observations on pachyzoid reproduction show macrolecithal oocytes and brooding of embryos, which seems to be the general pattern for this family. The occurrence of three new Zealandian species in a comparatively small geographical area far from the Atlantic indicates a high possibility of more species to discovered.
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Affiliation(s)
- Thomas Schwaha
- Department of Evolutionary Biology, University of Vienna, Schlachthausgasse 43, 1030, Vienna, Austria.
| | - Dennis P Gordon
- National Institute of Water and Atmospheric Research (NIWA), Wellington, New Zealand
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Schwaha T, Hirose M, Wood TS. Morphology of ctenostome bryozoans: 7. Hislopia, Echinella and Timwoodiellina. J Morphol 2024; 285:e21678. [PMID: 38361263 DOI: 10.1002/jmor.21678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2023] [Revised: 01/09/2024] [Accepted: 01/14/2024] [Indexed: 02/17/2024]
Abstract
Ctenostome bryozoans are a small group of gymnolaemates comprising less than 400 recent species. They are paraphyletic and ctenostome-grade ancestors gave rise to Cheilostomata, the most dominant and speciose taxon of Bryozoa in the present day. Investigations into ctenostomes are important for reconstructing character evolution among Gymnolaemata. As a continuation of studies on a morphological series of ctenostome bryozoans, we herein investigate six species of hislopiids, a small clade of three genera occurring in freshwater habitats. The general morphology of all species is similar in having primarily uniserial chains of encrusting zooids, which are mostly oval to ellipsoid and have a flattened frontobasal axis. Hislopia prolixa and Echinella placoides often have more slender zooids with a higher frontobasal axis. Apertures of hislopiids are quadrangular, lined by a thickened cuticle. Apertural spines are present in various lengths in E. placoides, Hislopia lacustris and Hislopia corderoi. The remaining cuticle is rather thin except at lateral areas, close to the pore-plates which are prominent in hislopiids because of abundant special and limiting cells. All species except H. corderoi and Timwoodiellina natans have a prominent collar obstructing the vestibulum, whereas the latter two species instead have an 'external collar' as cuticular, outer folds projecting over the aperture. Hislopiid lophophores carry eight, or more commonly 12-18 tentacles. The digestive tract is distinguished by an often highly elongated esophagus and/or cardia, with the latter always having a prominent bulbous part in the form of a proventriculus-or gizzard in E. placoides. The caecum is extensive in all species. In Hislopia the intestine is characteristically two-chambered with a proximal and distal part before entering an anal tube of various length. The latter is present in all species except T. natans and terminates in mid-lophophoral area. Oocytes in E. placoides are large and macrolecithal indicating brooding and the production of lecithotrophic larvae. Hislopia species produce small, oligolecithal ones, which suggests zygote spawning and planktotrophy. In general, the morphology is similar among the different hislopiids with characters of the gut aiding in delineating the genera Echinella and Timwoodiellina.
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Affiliation(s)
- Thomas Schwaha
- Department of Evolutionary Biology, University of Vienna, Vienna, Austria
| | - Masato Hirose
- School of Marine Biosciences, Kitasato University, Sagamihara-Minami, Kanagawa, Japan
| | - Timothy S Wood
- Department of Biological Sciences, Wright State University, Dayton, Ohio, USA
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Schwaha T, Waeschenbach A, De Blauwe H, Gordon DP. Morphology of ctenostome bryozoans: 6. Amphibiobeania epiphylla. J Morphol 2022; 283:1505-1516. [PMID: 36205214 PMCID: PMC9828531 DOI: 10.1002/jmor.21519] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Revised: 09/28/2022] [Accepted: 10/03/2022] [Indexed: 01/19/2023]
Abstract
Ctenostome bryozoans are unmineralized and mostly marine. Their lack of calcified skeletal features requires other characters to be considered for systematic and phylogenetic considerations. As a continuation of an ongoing series of studies, we herein investigate the morphology of Amphibiobeania epiphylla, a unique bryozoan inhabiting mangrove leaves that are highly exposed to tidal cycles and regular dry events according to the tidal cycle. Besides this interesting mode of life, the species was originally interpreted to be a weakly mineralized cheilostome bryozoan, whereas molecular data place it among ctenostome bryozoans. To elucidate the systematic and phylogenetic position of the genus and also find morphological adaptations to an extreme habitat, we investigated the morphology of A. epiphylla in detail. Zooids show a lophophore with eight tentacles and a simple gut with a prominent caecum, lophophoral anus and most notably a distinct gizzard in the cardiac region. Gizzard teeth are multiple, simple homogeneous cuticular structures. The cuticle of the zooid is rather uniform and shows no respective thickenings into opercular flaps or folds. Likewise, apertural muscles are represented by a single pair of muscles. There are no specific closing muscles in the apertural area like the operculum occlusors of cheilostomes. Most prominent within zooids is a spongiose tissue filling most of the body cavity. Although not properly understood, this tissue may aid in keeping animals moist and hydrated during prolonged dry times. In summary, all morphological characters support a ctenostome rather than a cheilostome affinity, possibly with Vesicularioidea or Victorelloidea. In addition, we provide new molecular data that clearly supports such a closer relationship.
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Affiliation(s)
- Thomas Schwaha
- Department of Evolutionary BiologyUniversity of ViennaViennaAustria
| | - Andrea Waeschenbach
- Department of Life Sciences, Invertebrate DivisionNatural History MuseumLondonUK
| | - Hans De Blauwe
- Department of Invertebrates, Scientific CollaboratorRoyal Belgian Institute of Natural SciencesBrusselsBelgium
| | - Dennis P. Gordon
- National Institute of Water and Atmospheric Research (NIWA)WellingtonNew Zealand
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Schwaha T, Winston JE, Gordon DP. Morphology of ctenostome bryozoans: 5. Sundanella, with description of a new species from the Western Atlantic and the Multiporata concept. J Morphol 2022; 283:1139-1162. [PMID: 35788975 PMCID: PMC9545146 DOI: 10.1002/jmor.21494] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 06/13/2022] [Accepted: 06/22/2022] [Indexed: 11/24/2022]
Abstract
Ctenostome bryozoans are a small group of gymnolaemates that comprise only a few hundred described species. Soft‐tissue morphology remains the most important source for analysing morphological characters and inferring relationships within this clade. The current study focuses on the genus Sundanella, for which morphological data is scarce to almost absent. We studied two species of the genus, including one new to science, using histology and three‐dimensional reconstruction techniques and confocal laser scanning microscopy. Sundanella generally has a thick, sometimes arborescent cuticle and multiporous interzooidal pore plates. The lophophore is bilateral with an oral rejection tract and generally has 30 or 31 tentacles in both species. The digestive tract shows a large cardia in S. floridensis sp. nov. and an extremely elongated intestine in Sundanella sibogae. Both terminate via a vestibular anus. Only parietodiaphragmatic muscles are present and four to six duplicature bands. Both species show a large broad frontal duplicature band further splitting into four individual bands. The collar is vestibular. Sundanella sibogae shows highly vacuolated cells at the diaphragm, whereas S. floridensis sp. nov. has unique glandular pouches at the diaphragmal area of the tentacle sheath. Such apertural glands have never been encountered in other ctenostomes. Both species of Sundanella are brooders that brood embryos either in the vestibular or cystid wall. Taken together, the current analysis shows numerous characteristics that refute an assignment of Sundanella to victorellid ctenostomes, which only show superficial resemblance, but differ substantially in most of their soft‐body morphological traits. Instead, a close relationship with other multiporate ctenostomes is evident and the families Pherusellidae, Flustrellidrae and Sundanellidae should be summarized as clade ‘Multiporata’ in the future.
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Affiliation(s)
- Thomas Schwaha
- Department of Evolutionary BiologyUniversity of ViennaViennaAustria
| | | | - Dennis P. Gordon
- National Institute of Water and Atmospheric Research (NIWA)WellingtonNew Zealand
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Schwaha T, Grischenko AV, Melnik VP. Morphology of ctenostome bryozoans: 4. Pierrella plicata. J Morphol 2021; 282:746-753. [PMID: 33675255 PMCID: PMC8048812 DOI: 10.1002/jmor.21344] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 02/26/2021] [Accepted: 03/03/2021] [Indexed: 11/26/2022]
Abstract
The genus Pierrella was originally created for a single fossil ctenostome bryozoan species from the Late Cretaceous, which is characterized by runner-like colonies, with zooids possessing a distinctive radial, folded aperture. Not long ago, a few specimens of a recent deep-sea congener, Pierrella plicata, were discovered and described from the Russian exploration area of the Clarion-Clipperton Fracture Zone, eastern Central Pacific Ocean. Owing to the lack of data on the internal morphology of this species, we investigated the soft-body morphology of P. plicata using serial sectioning and 3D-reconstruction in order to compare it to other more recently investigated ctenostome bryozoans and to infer the systematic position of the genus. The most striking peculiarity of the examined species is the radial aperture formed by multiple cuticular, pleated folds of the cystid wall. The cuticle is thickened into triangular-shaped folds in this area. An orifical sphincter underlies the folded aperture. Apertural muscles are present as a single pair of parieto-diaphragmatic muscles and four duplicature bands. The remaining polypide anatomy is mainly characterized by its miniature design: the lophophore has eight short tentacles and the digestive tract is one of the shortest and most compact ever observed in any bryozoan. A small intertentacular organ was detected at the lophophoral base. Taken together the genus Pierrella shows unique characters, such as the radial apertural folds that are closed by a series of orificial sphincter muscles, and its particularly small polypide. The general colony morphology resembles arachnidioidean ctenostomes whereas its internal morphology resembles alcyonidioidean species.
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Affiliation(s)
- Thomas Schwaha
- Department of Evolutionary BiologyUniversity of ViennaViennaAustria
| | - Andrei V. Grischenko
- Department of Invertebrate Zoology and Aquatic Ecology, Biological FacultyPerm State National Research UniversityPermRussia
- A.V. Zhirmunsky National Scientific Center of Marine Biology, Far East BranchRussian Academy of SciencesVladivostokRussia
| | - Viacheslav P. Melnik
- Joint Stock Company YuzhmorgeologiyaMinistry of Nature Resources and Environment of the Russian FederationGelendzhikRussia
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Schwaha T. Morphology of ctenostome bryozoans: 3. Elzerina, Flustrellidra, Bockiella. J Morphol 2021; 282:633-651. [PMID: 33576505 PMCID: PMC8048840 DOI: 10.1002/jmor.21334] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/07/2021] [Accepted: 02/09/2021] [Indexed: 11/08/2022]
Abstract
Ctenostome bryozoans are a small group of bryozoans whose soft‐tissue morphology has received only little attention. The present study represents the third in a series of articles dealing with the morphology of this clade of bryozoans. The morphology of three genera of Alcyonidioidea, that is, Bockiella (Alcyonidiidae), Elzerina and Flustrellidra (both Flustrellidridae), are analyzed using histology and 3D‐reconstruction techniques. The general zooidal morphology is similar and externally differs by the shape of the aperture. Zooids of Elzerina binderi are elongated in the fronto‐basal axis, whereas the other two are more flattened in this axis. All species show multiple pore‐complexes in their zooidal walls ranging from ~66 in E. binderi, to ~30 in F. hispida and to less than 10 in Bockiella. The aperture is bilabiate in flustrellidrids and roundish in Bockiella. Apertural muscles are present as parieto‐diaphragmatic muscles. The flustrellidrids have a large frontal duplicature band that further splits into four separate bands. The collar is diaphragmatic in Bockiella, but vestibular in the flustrellidrids. Lophophores are similar among the investigated species with a rejection tract in the flustrellidrids. The digestive tract shows differences in the extent and proportions of the caecum, which is large in the flustrellidrids and small in Bockiella; the anus is vestibular in all species. A funicular muscle of variable location is present in each species. Elzerina binderi has additional thin strands emanating from the digestive tract to the body wall. The parietal muscles show a unique situation in E. binderi with five bundles being present, two laterals and one distal. Several features aid in defining characters for the entire superfamily and the families Flustrellidridae and Alcyonidiidae. Besides the shape of the aperture, the frontal duplicature band, the vestibular collar and the large caecum are important. The set of characters also confirms recent notions that Bockiella belongs to the Alcyonidiidae.
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Affiliation(s)
- Thomas Schwaha
- Department of Evolutionary Biology, University of Vienna, Vienna, Austria
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Schwaha T, Grischenko AV, Melnik VP. Morphology of ctenostome bryozoans: 2. Haywardozoon pacificum, with implications of the phylogenetic position of the genus. J Morphol 2020; 281:1607-1616. [PMID: 32955145 PMCID: PMC7756298 DOI: 10.1002/jmor.21272] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Revised: 09/09/2020] [Accepted: 09/11/2020] [Indexed: 11/17/2022]
Abstract
The genus Haywardozoon represent a little known genus of ctenostome bryozoans that has only been found in the deep-sea. It forms small, mostly uniserial colonies lacking polymorphs. Zooids have a conspicuous apertural closure mechanism consisting of a cuticular lower lip that closes the aperture. The systematic placement of the genus remains uncertain, detailed morphological studies that include soft-body morphological traits are missing. Consequently, this is the first study analyzing H. pacificum by means of histological serial sections and 3d-reconstruction. Zooids are ovoid and in some cases solitary, that is, showing no interconnected zooids. Most prominent is the large vestibular wall that can be more than half of the total length of the zooid. Its vestibular wall is particularly lined by a complex, multilayered and branched cuticle. A single pair of lateral parieto-diaphragmatic muscles is present. The polypide is small and comprises about 17 tentacles. The digestive tract is short, has an elongated cardia, a vestigial caecum and a vestibular anus. An ovipositor/intertentacular organ and several oligolecithal oocytes were detected. Several aspects of zooidal morphology, including the structure of the bilateral aperture, parieto-diaphragmatic muscles, general structure of the gut and the thick cuticle, clearly indicate an association to the ctenostome superfamily Alcyonidioidea. Therefore, we reject the previous placement into Hislopioidea and suggest a possible association to pherusellid ctenostomes. New reproductive characters show that H. pacificum is a broadcaster contrary to some other deep-sea forms that are brooding. RESEARCH HIGHLIGHT: Morphology of ctenostome bryozoans remain little investigated. This contribution is the second of a series of detailed morphological analyses of this understudied clade of bryozoans. The morphological investigation of Haywardozoon pacificum revealed numerous characters that show a closer relationship to Flustrellididrae rather than Hislopiidae as previously assumed.
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Affiliation(s)
- Thomas Schwaha
- University of ViennaDepartment of Evolutionary BiologyViennaAustria
| | - Andrei V. Grischenko
- Department of Invertebrate Zoology and Aquatic Ecology, Biological FacultyPerm State National Research UniversityPermRussia
- A.V. Zhirmunsky National Scientific Center of Marine BiologyFar East Branch, Russian Academy of SciencesVladivostokRussia
| | - Viacheslav P. Melnik
- Joint Stock Company YuzhmorgeologiyaMinistry of Nature Resources and Environment of the Russian FederationGelendzhikRussia
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