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Zenodo
2021
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| Online-Zugang: | https://doi.org/10.5281/zenodo.20255263 |
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Inhaltsangabe:
- <p><b><i>Atolla wyvillei</i> Haeckel, 1880</b></p><p><b>Material examined.</b> One specimen, in 4% formaldehyde; ZRC.CNI.1405; station CP18 - Sunda Strait (between Sumatra and Java); Beam trawl; Depth 1060–1073 m; Bottom on: 6°10.758′S, 105°05.589′E; Bottom off: 6°11.587′S, 105°05.735′E; One specimen, in 4% formaldehyde; ZRC. CNI.1406; station CP14 - Sunda Strait (between Sumatra and Java); Beam trawl; Depth 1528–1539 m; Bottom on: 6°08.044′S, 104°50.086′E; Bottom off: 6°08.518′S, 104°49.879′E.</p><p><b>Description.</b> Coronatae with more than 8 rhopalia, alternating with equal number of tentacles; marginal lappets twice the number of tentacles. Atollidae with 8 adradial gonads; umbrella flat, with deep coronal groove. Flattened umbrella with deep coronal groove close to umbrella margin. Lappets smooth and elongated with round margins. Thick mesoglea.</p><p><b>Systematic remarks.</b> Both specimens are significantly damaged (see Fig. 1A), but due to the characteristic shape of the exumbrella and separate levels of tentacles and rhopalar pedalia, it is possible to refer to the specimens as genus <i>Atolla</i>. Of the 10 species of <i>Atolla</i> described to date, four are known to occur in the Indian Ocean around the Indonesian Archipelago, namely <i>Atolla parva</i>, <i>A. valdiviae</i>, <i>A. vanhoeffeni</i>, and <i>A. wyvillei</i> (from Kramp & Blanner, 1972, and Jarms & Morandini, 2019). All but <i>Atolla valdiviae</i> (doubtful species) are considered cosmopolitan in deep-water distribution. Sampling by the Dana cruise (1921–1922) in the coastal areas of the Indian Ocean discovered that <i>Atolla wyvillei</i> “was found almost everywhere” (Kramp & Blanner, 1972). The two <i>Atolla</i> specimens collected in this study from the Sunda Strait were approximately 35 and 61 mm, corresponding to most (if not all) species’ size range that are known to occur around the archipelago (see Table 2). None of the specimens from this expedition had any exceptionally long tentacle described by Russell (1959) or Repelin (1966) on <i>Atolla parva</i> or <i>A. wyvillei</i> (Fewkes, 1886). It could be that such characteristic tentacles were damaged during the collection process. However, it is possible to further diagnose their identity by the shape of radial septa (Fig. 1B): the paired diverging radial septa visible from the oral view of collected specimens are characteristic of <i>A. wyvillei</i> (see Jarms & Morandini, 2019).</p>