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The Bathyal Holothurians of the New Zealand Region
[Introduction]
Diagnosis: Spherical to U-shaped holothurians, with eight to ten tentacles, of which two are much larger than the others. Calcareous deposits large plates each with a spiny spire. Tube feet slightly developed, usually placed along the radii. (Partly after Heding, 1942).
Remarks: Heding (1942) proposed this family to include the genera Ypsilothuria Parrier and Echinocucumis Sars, both of which are distinguished from the Cucumariidae in possessing the unique scales in the bodywall together with simple finger-shaped tentacles, of which two are usually larger than the rest.
Panning (1949) reduced the family to the status of a subfamily (Ypsilothuriinae), and included five other genera, namely Ekmocucumis Heding, Abyssocucumis Heding, Psolicucumis Heding, Staurocucumis Ekman and Ypsilocucumis Panning. Ypsilocucumis was proposed (Panning, 1949) to accommodate the species Echinocucumis asperrima Theel. Deichman (1930) was of the opinion that this species is Sphaerothuria, while Heding (1942) regards the species as "a good Echinocucumis". In his diagnosis of the genus, Panning (1949) notes that the species E. asperrima has ten tentacles, and that in the bodywall there are large plates composed of many layers. Ypsilothuria (= Sphaerothuria) has eight tentacles according to Heding (1942) and eight to ten in the opinion of Deichman (1930). Deichmann notes that the two ventral tentacles may tend to become aborted. However, in view of Heding's emphatic statement that Ypsilothuria has "always ... eight tentacles", it is probably desirable to maintain the genus Ypsilocucumis Panning.
The remainder of the genera included in this group by Panning (1949) do not have the remarkable combination of characters found in Ypsilothuria, Echinocucumis and Ypsilocucumis, and I feel that they should be separated from the Ypsilothuriidae and replaced in the Dendrochirotida; they may constitute a family in themselves. As the status of some of these genera is in doubt (vide Clark and Deichmann, 1936; Heding, 1942), I am unwilling at present to propose a new taxon to accommodate these genera, and prefer to consider them as incertae sedis. A comparative study of these rather unusual holothurians is urgently required.
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| 1 (4) | Tentacles eight or ten, bodywall with large spired plates composed of many layers of calcareous material. | |
| 2 (3) | Tentacles ten | [Ypsilocucumis] |
| 3 (2) | Tentacles eight | Ypsilothuria (p. 6) |
| 4 (1) | Tentacles ten, spired plates of bodywall composed of a single layer of calcareous material | Echinocucumis (p. 7) |