taxonID	type	description	language	source
BE7D8789FFCEFF8522E807C3FB38FAC0.taxon	diagnosis	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.	en	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): 139-148, DOI: 10.11646/zootaxa.4742.1.9
BE7D8789FFCEFF8522E807C3FB38FAC0.taxon	type_taxon	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).	en	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): 139-148, DOI: 10.11646/zootaxa.4742.1.9
BE7D8789FFCEFF8522E807C3FB38FAC0.taxon	discussion	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).	en	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): 139-148, DOI: 10.11646/zootaxa.4742.1.9
BE7D8789FFCEFF8322E80297FEA5FE4B.taxon	description	(Figs. 1 – 3)	en	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): 139-148, DOI: 10.11646/zootaxa.4742.1.9
BE7D8789FFCEFF8322E80297FEA5FE4B.taxon	materials_examined	Material examined. Four specimens off the west coast of the Baja California Peninsula. TALUD XV St. 20 (26 º 30 ’ 42 ” N, 113 º 56 ’ 0 ” W), Aug. 1 2012, 1 specimen (TL 15.0 mm, W 9.6 mm), BS, 540 – 568 m (ICML-EMU- 11503); TALUD XVI-B St. 5 (28 º 48 ’ 00 ’’ N, 115 º 24 ’ 06 ” W), May 24 2014, 2 specimens (TL 15.0 and 10.0 mm, W 9.9 and 9.3 mm), BS, 772 – 776 m (ICML-EMU- 11504); TALUD XVI-B St. 7 (29 º 21 ’ 12 ” N, 115 º 39 ’ 08 ” W), May 31 2014, 1 specimen (TL 17.0 mm, W 12.3 mm), BS, 710 – 750 m (ICML-EMU- 11505). Additional material examined. Three specimens from the Gulf of California. Holotype, TALUD VI St. 26 (24 º 56 ’ 17 ” N, 109 º 06 ’ 39 ” W), Mar. 16 2001, (TL 15.0 mm, W 9.5 mm), BS, 1190 – 1270 m (ICML-EMU 8613). Paratypes, TALUD VIII St. 11 (24 º 54 ’ 24 ” N, 110 º 25 ’ 30 ” W), Apr. 17 2005, 2 specimens (TL 12.0 and 15.0 mm, W 6.8 and 8.3 mm), BS, 920 m (ICML-EMU 8614).	en	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): 139-148, DOI: 10.11646/zootaxa.4742.1.9
BE7D8789FFCEFF8322E80297FEA5FE4B.taxon	description	Description. Body semi-spherical or “ U ” shaped, slightly flattened in the central dorsal region (Fig. 2 A); ante- rior and posterior ends like sharp retractile cones (in the preserved material no more than 6 mm long). Holothuroids covered by perforated tables and plates, organized in two layers superimposed as roof tiles (Fig. 3 B). Perisoma rough to the touch by the spires of the plates pointing outwards. Ambulacral feet scattered along the radius, small and rounded. At anterior end two long and digitiform tentacles, covered by small granules, observed exposed only in one specimen (TALUD XVI-B, St. 7). In the remaining specimens the crown of tentacles, including the two largest, and the introvert were contracted inside the body. Ossicles of the body wall in two forms: (1) wide, perforated tables (921 – 1466 µm across) with an eccentric spire (Fig. 2 B, I, II, VI); spire of the table conical, very long (up to 755 µm high), consisting of a network of pillars (Fig. 3 A, I), and (2) smaller (359 – 861 µm across) plates oval, semi-square or thimble-shaped, without spire (Fig. 2 B, III, IV, VII, IX, X), disposed as unions of plates between several plates with spire (Fig. 2 B V, VII) and at the ends of body. Dorsal and ventral ossicles similar in shape; smaller plates without spire at the ends of body. Tentacles with curved bars, perforated at the ends, and with small teeth in the margin (139 – 227 µm long) (Fig. 3 A, II). Color. Body and tentacles white (preserved material).	en	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): 139-148, DOI: 10.11646/zootaxa.4742.1.9
BE7D8789FFCEFF8322E80297FEA5FE4B.taxon	discussion	Remarks. The specimens collected off the west coast of the Baja California Peninsula present the same morphological characteristics as those observed in the holotype (collected in the Gulf of California, on the east coast of the Baja California Peninsula). These specimens feature the same characteristics in the shape of the ossicles and in the external shape of the animal as described by Massin & Hendrickx (2011). The two forms of spicules that cover the body of the animal were observed in all specimens, as superimposed layers, one of the main characteristics of Y. californiae. The size of the organisms was also similar on both sides of the peninsula. Based on the new material, the length range for Y. californiae is from 10 (present research) to 21 mm (Massin & Hendrickx 2011). However, it is necessary to clarify that the size of organisms is a very plastic characteristic, little used to compare communities of holothurians.	en	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): 139-148, DOI: 10.11646/zootaxa.4742.1.9
BE7D8789FFCEFF8322E80297FEA5FE4B.taxon	distribution	Distribution. Northern Mexican Pacific, off the west coast of the Baja California Peninsula from 29 º 21 ’ 12 ” N to 26 º 30 ’ 42 ” N, and in the central and southern Gulf of California, Mexico.	en	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): 139-148, DOI: 10.11646/zootaxa.4742.1.9
BE7D8789FFCEFF8322E80297FEA5FE4B.taxon	biology_ecology	Ecology. Environmental conditions available for the new specimens collected off western Baja California (outside the Gulf of California) were different from those observed with the type material (Gulf of California): depth, 540 – 776 m vs. 377 to 1270 for the type material; epibenthic parameters values, 0.15 – 0.28 ml O 2 / l and 5.34 – 8.38 ° C vs. 0.20 – 1.40 ml O 2 / l and 3.7 – 10.5 ° C for the type material (see Massin & Hendrickx 2011). In addition, the speci- mens from off the western Baja California Peninsula were collected in salinity of 34.42 – 34.51 ups (no data available for the type material). The new material occurs in a variety of sediments made of 7.75 – 11.82 % clay, 45.16 – 77.67 % silt and 11.09 – 47.08 % sand, with an organic carbon content of 3.18 – 5.20 mg / g (5.47 – 8.95 % of organic matter) (Table 1). Density of organisms. Ypsilocucumis californiae was not abundant off western Baja California Peninsula, with density estimated from 2.63 orgs / ha (TALUD XV, St. 20) to 3.94 orgs / ha (TALUD XVI-B, St. 7) (Table 1), in comparison with others species of holothuroids collected in the same area by the same two cruises TALUD. Such was the case of Synallactes virgullasolida for which density values were reported as up to 170.32 orgs / ha (Luna-Cruz & Hendrickx 2018).	en	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): 139-148, DOI: 10.11646/zootaxa.4742.1.9
