Classical and computed tomographic anatomical analyses in a not-so-cryptic Alviniconcha species complex from hydrothermal vents in the SW Pacific

Type Article
Date 2020-05
Language English
Author(s) Laming SvenORCID1, 2, Hourdez Stéphane3, Cambon-Bonavita Marie-AnneORCID2, Pradillon FlorenceORCID1
Affiliation(s) 1 : Ifremer, Laboratoire Environnement Profond (REM/EEP/LEP), Plouzané, France
2 : Ifremer, Univ Brest, CNRS, UMR6197, Laboratoire de Microbiologie des Environnements Extrêmes (REM/EEP/LM2E), Plouzané, France
3 : UMR 8222 CNRS-Sorbonne Université, Laboratoire d’écogéochimie des environnements benthiques (LECOB), Banyuls-sur-Mer, France
Source Frontiers In Zoology (1742-9994) (Springer Science and Business Media LLC), 2020-05 , Vol. 17 , N. 1 , P. 12 (27p.)
DOI 10.1186/s12983-020-00357-x
WOS© Times Cited 3
Keyword(s) Deep sea, Chemosymbiotic, Periostracum, Gastropod, Habitat partitioning, Computed tomography, Histology, Taxonomy, 3D model
Abstract

The chemosymbiotic gastropod Alviniconcha (Provannidae), first described in 1988, is one of the most emblematic hydrothermal-vent taxa described from the Central Indian Ridge and the Southwest (SW) Pacific. Symbiotic bacteria found in the gill of Alviniconcha are thought to be their principal source of nutrition. In the SW Pacific, species distributions for A. kojimai, A. boucheti – and to a lesser extent A. strummeri – overlap. While Alviniconcha species do not appear to truly co-exist in these highly energetic but spatially limited habitats, certain species regularly co-occur within a single vent field and in rare instances, the same edifice. Past research suggests that SW-Pacific Alviniconcha species might aggregate around fluids with distinct geothermal profiles. These small-scale distribution patterns have been attributed to differences in their symbiont assemblages or host physiologies. However, little is known about the anatomy of most Alviniconcha species, beyond that detailed for the type species Alviniconcha hessleri, whose geographic range does not overlap with other congeners. In fact, species within this genus are currently described as cryptic, despite the absence of any comparative morphological studies to assess this. To test whether the genus is genuinely cryptic and identify any functional differences in host anatomy that might also mediate habitat partitioning in SW Pacific species, the current study examined the morphoanatomy of A. kojimai, A. boucheti and A. strummeri from the Fatu Kapa vent field, an area of hydrothermal activity recently discovered north of the Lau Basin near the Wallis and Futuna Islands and the only known example where all three species occur within adjacent vent fields. A combination of detailed dissections, histology and X-ray computed tomography demonstrate that A. kojimai, A. strummeri and A. boucheti are readily identifiable based on shell morphology and ornamentation alone, and therefore not truly cryptic. These traits provide a rapid and reliable means for species identification. However, aside from some subtle differences in radular morphology, these species of Alviniconcha exhibit conserved anatomical features, providing no evidence that functional host anatomy is implicated in habitat partitioning. This provides support for the current belief that host-species distributions are probably governed by symbiont-mediated physiological factors.

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Publisher's official version 27 25 MB Open access
Additional file 1. 3D visualisation – with interactive model – of gross anatomy in Alviniconcha kojimai. Larger version of the CT-model schematic in Fig. 4a depicting the gross anatomy of A. kojimai. 1 16 MB Open access
Additional file 2. 3D visualisation – with interactive model – of gross anatomy in Alviniconcha strummeri. CT-model schematic of A. strummeri depicting the gross anatomy. ... 1 12 MB Open access
Additional file 3. Specimens of A. kojimai with and without last shell whorl. Photographic plate of gross anatomy, like that of Fig. 2, but for Alviniconcha kojimai. 1 350 KB Open access
Additional file 4. Appearance and quality of CT volumes for each species, given separate fixation regimes. CT volume screenshots summarising the appearance and utility of the three specimens scanned, 1 96 KB Open access
Additional file 5. Additional morphological features identified during dissections (A. kojimai). Photographs that identify additional anatomical details that were not core to the manuscript but merit 1 330 KB Open access
Additional file 6. Examination of jaws and anterior radula. Scanning-electron microscopy images of one of the paired jaws and of the anterior-to-posterior comparison of the radula, providing evidence 1 191 KB Open access
Additional file 7. Supplementary methodology (and methodological figures therein). Additional information on the histological approaches used in the current study and some 7 669 KB Open access
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How to cite 

Laming Sven, Hourdez Stéphane, Cambon-Bonavita Marie-Anne, Pradillon Florence (2020). Classical and computed tomographic anatomical analyses in a not-so-cryptic Alviniconcha species complex from hydrothermal vents in the SW Pacific. Frontiers In Zoology, 17(1), 12 (27p.). Publisher's official version : https://doi.org/10.1186/s12983-020-00357-x , Open Access version : https://archimer.ifremer.fr/doc/00628/74048/