Echinopsolus sanamyanorum Panina, Stepanov, Smirnov & Martynov, 2020

Panina, Elena G., Stepanov, Vadim G., Smirnov, Alexei V. & Martynov, Alexandr V., 2020, Two new species of holothurians of the genus Echinopsolus Gutt, 1990 (Echinodermata: Dendrochirotida: Cucumariidae) from the North-Western Pacific, Zootaxa 4789 (1), pp. 233-246 : 235-238

Echinopsolus sanamyanorum Panina, Stepanov, Smirnov & Martynov sp. nov.

( Figs 1–5 )

Psolidae gen. sp.— Stepanov et al. 2012: 19–20, figs. 12–15; Smirnov 2013: 199.

Psolidae gen. sp. 1— Stepanov & Panina 2015: 46–47.

Holotype. RAS, Cat. No. 144-143, male, specimen 11 mm long, 12 September 2008, Avacha Gulf (Listvenichnaya Bay, Cape Piramidalny), 158°34.315′ N, 52°22.765′ E, 19 m depth, stone, boulder, 8°C water temperature, collected by SCUBA diving, collector N.P. Sanamyan (Kamchatka Branch of Pacific Geographical Institute of the Far-Eastern Branch of the Russian Academy of Sciences ). No further specimens known.

Type locality. Avacha Gulf (southeast coast of Kamchatka).

Etymology. The species was named in honor of K.E. Sanamyan and N.P. Sanamyan (Kamchatka Branch of Pacific Geographical Institute of the Far-Eastern Branch of the Russian Academy of Sciences) who collected the holotype and are outstanding scientists in the field of taxonomy of invertebrates.

Diagnosis. Color in life is yellow-pink. The mouth and anus are displaced to the dorsal side. Ventral side is flattened like a sole. The skin is thick and wrinkled on the dorsal side. Tube feet are arranged in three longitudinal rows on the ventral side; on the ventrolateral radius there are 3-4 tube feet in transverse rows, on the mid-ventral radius—one zigzag row. Six tube feet near the mouth on the dorsal side. Tentacles 10, ventral pair smaller than the others. Ossicles are perforated plates and spindle-shaped rods.

Description of the holotype. Length— 11 mm, width— 7 mm, height 4 mm to the top of mouth cone, 3 mm up to the anus cone. Color in life is yellow-pink. The mouth and anus are displaced to the dorsal side. Ventral side is flat, like a sole. Body is low (ratio of height-length = 1/2), mouth and anus are not raised ( Fig. 1 ). The skin is thick and wrinkled on the dorsal side. Tube feet are arranged in three longitudinal rows on the ventral side; on ventrolateral radii 3-4 tube feet in transverse rows, on mid-ventral radius one zigzag row. Ossicles are perforated plates and spindle-shaped rods. Tentacles 10, ventral pair smaller than the others. Retractors are attached to longitudinal muscles at 1/3 distance from anterior end. One Polian vesicle, broad in the middle and narrow at the distal end ( Fig. 2 A ). Madreporite and stone canal are absent.

The calcareous ring with 10 segments is low with short posterior processes ( Fig. 2 B ). Radial segments have a deep posterior notch and a tall anterior projection, which is taller than interradial segments.

Thick oval plates with a wavy edge predominate in the body wall of the ventral side. The plates bear numerous large knobs and round holes scattered over the whole surface (usually 1–2 holes in transverse rows); length 150–244 µm ( Fig. 3 A ). There are also thick triangular and round ossicles with many holes and a few knobs; thin ossicles of different shapes and without knobs, also crosses and rods; length 150–263 µm ( Fig. 3 B ). Tube feet have a round end plate of lacey form (length 169–188 µm; Fig. 3 C ) and perforated plates. Ossicles of the dorsal body are perforated plates and branch rods (length 102–214 µm; Fig. 4 ). Spindle rods were not found. Ossicles of the tentacles are the plates with few holes, crosses and ramified rods (length 90–200 µm; Fig. 5 ).

Figures

FIGURE 1. Echinopsolus sanamyanorum: A—side view, B—top view, C—ventral view (Photo by K.E. Sanamyan).

FIGURE 2. Echinopsolus sanamyanorum: A—Polian vesicle, B—segments of the calcareous ring (R—radial segment, IRinterradial segment).

FIGURE 3. Echinopsolus sanamyanorum: A, B—ossicles of ventral body wall, C—end plate of the tube feet.

FIGURE 4. Echinopsolus sanamyanorum. Ossicles of the dorsal body wall.

FIGURE 5. Echinopsolus sanamyanorum. Ossicles of the tentacles.