Ypsilocucumis Panning, 1949

Luna-Cruz, Ana K. & Hendrickx, Michel E., 2020, Rediscovery of the deep-water species Ypsilocucumis californiae Massin & Hendrickx, 2011 (Echinodermata; Holothuroidea; Ypsilothuriidae) in western Mexico, Zootaxa 4742 (1), pp. 139-148 : 141

Genus Ypsilocucumis Panning, 1949

Diagnosis (from Panning 1949, amended herein). Ten tentacles. Calcareous ring without fork tails, made up of ten pieces. Ossicles in body wall like large plates of several layers of mesh, with or without a central or eccentric accessory as a spire; spire composed of many layers of mesh. Body covered by multilayered ossicles; in small specimens (length of <15 mm, not considering oral and anal cones) the body may present many single layered ossicles. Retractile oral and anal cones.Ambulacral feet very small, difficult to observe, present along the radius, more visible towards the ends of the body.

Type species. Echinocucumis asperrima Théel, 1886 , accepted as Ypsilocucumis asperrima . Type locality. Three syntypes from off Isle of Pines, Cuba, 289 m (158 ftm), HOL-291 MCZ; Frederiksted, U.S.A. Virgin Island, 329 m (180 ftm), HOL-292 MCZ; Kingston, Jamaica, 274 m (150 ftm), HOL-293 MCZ ( Théel 1886).

Remarks on the genus. The genus Ypsilocucumis was described by Panning (1949) as part of the order Dendrochirotida , family Cucumariidae Ludwig, 1894 , subfamily Ypsilothuriinae Heding, 1942 . Panning (1949) included as part of this genus the species Ypsilocucumis asperrima ( Théel, 1886) , Ypsilocucumis turricata (Vaney, 1906) , and Ypsilocucumis scotiae (Vaney, 1906) . Subsequently, Pawson & Fell (1965) proposed the new order Dactylochirotida Pawson & Fell, 1965, within which they placed the family Ypsilothuriidae . This family included the genera Ypsilocucumis , Ypsilothuria Perrier E., 1886 , and Echinocucumis M. Sars, 1859 . Years later, O’Loughlin (2002) and O´Loughlin et al. (2009) moved two of the species of Ypsilocucumis proposed by Panning (1949) to different genera in the family Paracucumidae Pawson & Fell, 1965 : Y. turricata (Vaney, 1906) was moved to the genus Paracucumis Mortensen, 1925 ( O’Loughlin 2002) , and Y. scotiae (Vaney, 1906) to the genus Crucella Gott, 1990 ( O’Loughlin et al. 2009), leaving the genus Ypsilocucumis with only one valid species.

Smirnov (2012) reclassified Ypsilocucumis and Ypsilothuria into the order Dendrochirotida (subclass Holothuriacea Smirnov, 2012 and family Ypsilothuriidae ). Smirnov’s (2012) classification omitted the order Dactylochirotida which he considered to be polyphyletic and he transferred their members to the order Dendrochirotida . Smirnov (2012) reassigned Echinocucumis to the Cucumariidae , subfamily Cucumariinae Ludwig, 1894 (sensu Panning 1949), into the order Dendrochirotida . Massin & Hendrickx (2011), who described the second known species of Ypsilocucumis , kept the family in the Dactylochirotida as proposed by Pawson & Fell (1965).

Morphologically speaking, we consider Ypsilocucumis as part of the Ypsilothuriidae and is close to the genera Ypsilothuria and Echinocucumis which we classify in the Dendrochirotida and not in the Dactylochirotida. Several characters separate members of Ypsilocucumis from Ypsilothuria . In Ypsilothuria , there are eight tentacles (E. Perrier 1886; Panning 1949; Ludwig 1894, as Sphaerothuria ), the anterior and posterior ends of the body are generally covered by perforated plates without spire ( Panning 1949), and the ossicles form a real test ( Heding 1942). The genus Echinocucumis M. Sars, 1859 is separated from Ypsilothuria by the presence of tapered, non-retractile oral and anal ends, usually upturned, and by large, imbricating ossicles that cover the body like perforate plates in a single-layered, each having a tall spine arising near the plates margin ( O´Loughlin et al. 2015).