Holothuria (Metriatyla) cyrielle VandenSpiegel

Samyn, Yves & Vandenspiegel, Didier, 2016, Sublittoral and bathyal sea cucumbers (Echinodermata: Holothuroidea) from the Northern Mozambique Channel with description of six new species, Zootaxa 4196 (4), pp. 451-497 : 462-464

Holothuria (Metriatyla) cyrielle VandenSpiegel sp. nov.

( Fig. 6 A – G)

Material examined. Type material: IE-2007-752 (holotype and 1 paratype, sampled in front of Nazendry Bay ) Comparative material examined: ZMB Ech 1681 (holotype of Holothuria (Metriatyla) martensii Semper, 1868 ( Fig. 5 ); Ambon, Indonesia; leg. V. Martens; unknown depth).

Non-type material: IE-2007-753 (1 specimen, dredged between Majunga and Cape Saint-André); IE-2007- 810 (1 specimen, dredged between Nosy-Bé and Banc du Leven).

Type locality. Madagascar, in front of Nazendry Bay , Miriky St. CP 3240 (Decimal coordinates: -14.5; 47.45) Etymology. This species is named after Cyrielle VandenSpiegel , daughter of Joelle Dellis and D. VandenSpiegel, in recognition of her patience when her dad is writing up some taxonomic work at home. The species epithet has been put in apposition.

Known geographical distribution. Known from the type locality ( Nazendry Bay ), between Majunga & Cape Saint-André and between Nosy Be and ‘ Banc du Leven’

Taxonomic description (holotype and paratype). External anatomy - Holotype 190 mm long and 30 – 60 mm wide, with maximum circumference of 170 mm. Paratype 210 mm long and 30 – 45 mm wide, with maximum circumference at mid-body of 120 mm (fig. 6A,B). Body tapering towards both ends. Body wall heavily wrinkled, especially ventrally; very gritty to the touch. Bivium convex. Trivium flat. Bivium separated from trivium by irregular row of enlarged lateral papillae. Mouth ventral, surrounded by 18 small tentacles in paratype (number could not be determined in holotype). Anus terminal, 4 (holotype) to 13 (paratype) mm wide, surrounded by some ten evenly spaced papillae. Color in alcohol: bivium brownish, with scattered, evenly spread, short papillae, each separated by narrow dark brown ring. Trivium lighter brown, covered by small and few, evenly spread, tube feet; no darker ring surrounds ventral tube feet.

Internal anatomy —Calcareous ring with stout radial and interradial pieces; interradials slightly wider and longer than interradial ones; radial pieces with deep anterior and posterior notch; interradial pieces with prominent anterior tooth and convex posterior margin. Stone canal single, straight, 30 mm long in holotype, ending in a well developed madreporite, 12 mm long in paratype. Polian vesicle single, club-shaped, 30 mm long in holotype, 35 mm long in paratype. Radial canal positioned nearly 1 cm below calcareous ring. Tentacle ampullae small, 5 – 8 mm long. Gonad well developed, in single tuft with long tubules that bifurcate only occasionally. Gut filled with fine muddy sediment. Respiratory trees well developed, with left one reaching mid-body while right one goes up to oral end. Longitudinal muscles bifid, flat and wide (10 mm in paratype, 15 mm in holotype) with edges attached to body wall. Inner side body wall brownish, irregularly marked by by purplish-brown spots. Cloaca 35 mm long in paratype, 45 mm long in holotype. Cuvierian tubules present, very thick.

Ossicles —Tentacles with curved, occasionally branching, slightly rugose rods, 110 – 480 µm long (fig. 6C). Ventral and dorsal body wall with nodose buttons and tables (fig. 6D,E). Tables disc 50 – 70 µm across, perforated by central holes and numerous small peripheral holes, positioned in a ring; rim of disc undulating to spiny, spire with four short smooth to spiny pillars (70 – 74µm high), united by one or more cross beams and ending in a spiny crown. Buttons moderately to very nodulose, 43 – 90 µm long, perforated by 3 to 7 pairs of holes, holes larger in the dorsal buttons (fig. 6D,E). Ventral tube feet with perforated rods, 110 – 300 µm long, and plates, 100 – 208 µm long, in addition to tables and buttons similar to the ones in the body wall (fig. 6G). Dorsal tube feet with massive plates (up to 265µm long and 90µm wide) in addition to buttons and tables similar to the ones from the dorsal body wall (fig. 6F), rods absent. Longitudinal and cloacal suspensor muscles, gonad and cloaca devoid of ossicles.

Remarks. The tables in the body wall of Holothuria (Metriatyla) cyrielle sp. nov. have a rugose spire and one to several cross-beams. They resemble those in the original description of Holothuria (Metriatyla) martensii Semper, 1868 (See Semper 1868: pl 30, fig 16 a&b). We have examined the holotype of H. martensii which we located in the Zoological Museum of Berlin and come to the conclusion that they are different species because H. martensii also has tables with smooth tall spires in the body wall, as noted by Théel (1886), Panning (1934) and Liao (1997), and buttons which are less nodulous.

Thandar (pers. comm.) found a specimen of the KwaZulu-Natal Coast in South Africa, at depth of approximately 100 m, that is very close, if not identical, to the species we here recognize.

H. cyrielle sp. nov. has a bathymetric range from 257 – 580 m (100 – 580 m if Thandar’s (pers. comm.) record proves indeed the same species), which makes it the deepest species in Metriatyla ever recorded. It is also interesting to note that H. cyrielle confirms that Holothuria species with Cuvierian tubules can reach bathyal depths as reported by O’Loughlin et al. (2009) for H. (Panningothuria) austrinabassa O’Loughlin, 2007 , which is known to occur at 800 m depth.

Figures

FIGURE 5. Holothuria (Metriatyla) martensii Semper, 1868. Label and dorsal view of the holotype.

FIGURE 6. Holothuria (Metriatyla) cyrielle sp. nov. A – B: dorsal (A) and ventral (B) views of holotype; C – G: SEM photos of ossicles from tentacles (C), dorsal body wall (D), ventral body wall (E), dorsal tube feet (F) and ventral tube feet (G). Scale bars: A, B = 1 cm; C = 100 µm; E – G = 20 µm.