Psolidium kharlamenkoi Panina, Stepanov & Martynov, 2021

Panina, Elena G., Stepanov, Vadim G. & Martynov, Alexander V., 2021, Psolidium kharlamenkoi-a new species of holothurian (Holothuroidea Dendrochirotida: Psolidae) from the Kuril Islands, Zootaxa 4995 (2), pp. 266-280 : 268-275

Psolidium kharlamenkoi Panina, Stepanov & Martynov n. sp.

2015 Psolidium sp. —Kharlamenko et al.: 419–421, 423, fig. 1, tables 1, 2.

Holotype. RAS Pacific Institute of Bioorganic Chemistry , Cat. No. 458/466 (16 July 2011, R / V Academic Oparin, cruise 41, trawl 18, station 23, 46° 58.0′ N – 46° 58.0′ N, 152° 12.6′ E – 152° 11.7′ E, substrate—gravel, pebble, 307– 215 m depth, collectors V. I. Kharlamenko and K. V. Minin).

Paratypes. RAS Pacific Institute of Bioorganic Chemistry , Cat. Nos. 457/465-1, 457/465-2, 191/358: three specimens (17 July 2011, R / V Academic Oparin, cruise 41, trawl 24, station 29, 46° 57.82′ N – 46° 57.78′ N, 152° 17.26′ E – 152° 14.5′ E, substrate—broken shells, sand, depth 440– 350 m, collector K. V. Minin) .

Other investigated samples. RAS P.P. Shirshov Institute of Oceanology, Cat. No. ECH02192: one specimen (06 June 1950, R / V Vitjaz, cruise 4, station 426, 47° 41.7′ N, 153° 04.9′ E, 462 m depth, gear Petersen dredge) .

RAS A. V. Zhirmunsky Institute of Marine Biology , Cat. No. 606/606: one specimen (08 July 1987, R / V Tihookeansky, Uriy Island, station 7, sample 19, 490 m depth, substrate—silty sand, pebble, gravel, collectors V. A.Pavluchkov and A.A. Kubanin) .

RAS A. V. Zhirmunsky Institute of Marine Biology , Cat. No. 605/605: one specimen (10 July 1987, R / V Tihookeansky, Shikotan Island, station 29, profile 3, sample 67, 406 m depth, substrate—sand, pebble, gravel) .

RAS A. V. Zhirmunsky Institute of Marine Biology , Cat. No. 583/585-1, 583/585-2: two specimens (11 July 1987, R / V Tihookeansky, Shikotan Island, 43°36′N, 147°19′E, station 28, profile 4, sample 74, 500 m depth, sub- strate—sand, pebble, gear dredge, collector S.D. Grebelniy) .

RAS Pacific Institute of Bioorganic Chemistry , Cat. Nos. 90/315-1, 90/315-2: two specimen (24 July 2011, R / V Academic Oparin, cruise 41, trawl 46, station 53, 45° 38.35′ N – 45° 39.15′ N, 148° 23.9′ E – 148° 24.1′ E, sub- strate—silty sand, 450 m depth, collectors V. I. Kharlamenko and K. V. Minin) .

RAS Pacific Institute of Bioorganic Chemistry , Cat. Nos. 112/354-1, 112/354-2: two specimens (29 July 2011, R / V Academic Oparin, cruise 41, trawl 54, station 62, 45° 43.55′ N – 45° 44.13′ N, 148° 14.0′ E – 148° 14.24′ E, 435– 350 m depth, collector K. V. Minin) .

Diagnosis. Body length up to 35 mm. Mouth and anus on elevated cones above the body surface. The anal cone being more than twice the height of the oral cone in large specimens. About 6–9 scales between the anus and mouth, one tube feet is located on each dorsal and lateral scale. Tube feet are arranged in two longitudinal rows on the ventrolateral radius, but the mid-ventral radius has tube feet in one longitudinal row or only at the anterior or posterior ends. Retractor muscles originate half way along the longitudinal muscle bands. Ten dendritic tentacles, of which the two ventral ones are smaller. Calcareous ring is low without posterior processes.

Ossicles of the sole are perforated flat plates and oval, rounded sclerites with a few round holes (1–4) with or without knobs. Ossicles of the sole in small individuals of the species have numerous knobs and holes. There are also crosses. Ossicles of the ventral tube feet are flat, oval perforated plates without knobs with a variable number of larger holes (1–11), and crosses; end plates of the ventral tube feet have numerous holes. Ossicles of the tentacles are delicate perforated plates without knobs. They are triangular, quadrangular, rhomboid, curved, and oval in shape, with a variable number of holes. Ossicles of the dorsal side are thick, multi-layered scales with thin edges. There are also three-dimensional, spherical, and ellipsoid bodies.

Type locality. Kuril Islands : 43°36′– 47°41.7′ N, 147°19′E – 153°04.9′E .

Etymology. The species was named after Vladimir I. Kharlamenko (A.V. Zhirmunsky Institute of Marine Biology of the FEB RAS), who suggested that the present material might belong to an undescribed species.

Description of the holotype. Color in life is white. The holotype is 35 mm long, height at the mouth cone is 15 mm, height in the middle of the body is 14 mm, 24 mm at the anal cone, length of the sole is 30 mm, width of the sole 14 mm ( Figure 1 ).

Eight scales between anus and mouth, scale diameter about 1.5 mm; distance between oral-anal openings 19 mm; one tube foot is located on each dorsal and lateral scale. Tube feet are arranged in two longitudinal rows on the ventrolateral radii, while the mid-ventral radius has one longitudinal row, which widens at the anterior and posterior end. Ten dendritic tentacles present, the two mid-ventral ones of which are smaller than the others. Retractor muscles originate half way along the longitudinal muscle bands. Polian vesicle, madreporite and stone canal are absent.

Calcareous ring without posterior processes; front borders of the plates are pointed; the radial plates are 3 mm high, interradial ones about 2.7 mm. Radial segments have a deep triangular posterior notch, while interradials have a shallow notch ( Fig. 2A ).

Ossicles of the sole are flat perforated plates, oval or rounded in shapes with a few round holes (1–4) with or without knobs; and also crosses ( Fig. 3 ). Ossicles of the ventral tube feet are flat perforated plates, oval to round in shapes without knobs and a variable number of larger holes (1–11) ( Fig. 4A ), crosses ( Fig. 4B ) and flat end plates with numerous holes like a honeycomb ( Fig. 4C ). Ossicles of the dorsal tube feet are perforated plates without knobs, but with a variable number of holes, and some crosses ( Fig. 5 ). Ossicles of the tentacles are delicate perforated plates and crosses ( Fig. 6 ). They are triangular, quadrangular, rhomboid, curved, and oval in shape with a variable number of holes. Ossicles of the introvert are perforated plates without knobs and crosses ( Fig. 7 ). The perforated plates are triangular, quadrangular, rhomboid, curved, and oval in shape with a variable number of holes. Ossicles of the oral disc are thick-branched rods, perforated plates, and compact globules. Ossicles of the dorsal side are scales with a single layer around the edges and a thicker center, similar to honeycombs ( Figs 8A , 9A ). They are oval, rounded, and triangular in shape. In addition, three-dimensional spherical and ellipsoid ossicles ( Figs 8B , 9B ), and flat perforated plates with few holes and knobs ( Fig. 8C ) occur.

Description of the paratypes. Cat. No. 457/465-1, the specimen is 25 mm long, height is 13 mm at the mouth cone, 9 mm in the middle of the body, 16 mm at the anal cone; the length of the sole is 21 mm, its width 10 mm ( Fig. 10A ). Six scales between the anus and mouth, with a scale diameter of 1.2–1.5 mm. Distance between oral-anal openings 10 mm. Dorsal and lateral scales have a single tube foot each. Tube feet are arranged in two longitudinal rows on the ventrolateral radii. The mid-ventral radius has one longitudinal row, which bifurcates at the anterior and posterior ends. Ten dendritic tentacles present, the two mid-ventral ones of which are smaller than the others. There is one Polian vesicle, with an orange madreporite at the end of the stone canal. They are attached to the calcareous ring on the dorsal interradius.

Cat. No. 457/465-2 —is similar to the previous specimen. It is 24 mm long, height at the mouth cone is 10 mm, height in the middle of the body is 9 mm, 14 mm at the anal cone; length of the sole is 21 mm, width of the sole 7 mm ( Fig. 10B ). Six scales between the anus and mouth. Distance between oral-anal openings 12 mm. There is one Polian vesicle, 5.5 mm long; sacciform, inflated in the middle and pointed on the distal end ( Fig. 2B ). It is attached to the calcareous ring on the dorsal interradius. Madreporite and stone canal are absent in specimen 457/465-2.

Cat. No. 191/358— the specimen is 22 mm long, height at the mouth cone is 9 mm, height in the middle of the body is 8 mm, 13 mm at the anal cone; length of the sole is 15 mm, width of the sole 11 mm ( Fig. 10C, D ). Six scales between the anus and mouth. Distance between oral-anal openings 7 mm. Tube feet are arranged in 2 longitudinal rows on the ventrolateral radii, and only at the ends on the midventral radius. There is one Polian vesicle, 5 mm long. Its form is identical with paratype Cat. No. 457/465-2. There is one stone canal with a rounded madreporite, diameter 0.4 mm.

Description of additional material. In small specimens (less than 15 mm) oral and anal cones protrude slightly above the surface of the body ( Fig. 11 ). Ossicles of the ventral body wall of small specimens of P. kharlamenkoi , unlike the holotype and paratypes, bear numerous holes and knobs ( Fig. 12A ). The end plates of tube feet are much smaller and bear fewer holes ( Fig. 12B ).

Distribution. Kuril Islands: from Shikotan to Rasshua (43° 36′ N – 47° 41.7′ N, 147° 19′ E – 153° 04.9′ E ( Fig. 13 ).

Figures

FIGURE 1. External view of the holotype Psolidium kharlamenkoi n. sp. Kamchatka Branch of Pacific Geographical Institute, Far-Eastern Branch of Russian Academy of Sciences, Cat. No. 458/466. (Photo by K.E. Sanamyan). Side view.

FIGURE 2. Psolidium kharlamenkoi n. sp., line drawings. A—dorsal part of calcareous ring (holotype (Cat. No. 458/466), R—radial segment, IR—interradial segments), B—Polian vesicle (paratype, Cat. No. 457/465-2).

FIGURE 3. SEM images of ossicles from the ventral body wall of the holotype Psolidium kharlamenkoi n. sp., scanning electron micrograph (SEM) (Cat. No. 458/466).

FIGURE 4. Line drawings of ossicles from the ventral tube feet of the holotype Psolidium kharlamenkoi n. sp. (Cat. No. 458/466). A—perforated plates, B—crosses, C—tube foot end plate.

FIGURE 5. Line drawings of ossicles from the dorsal tube feet of the holotype Psolidium kharlamenkoi n. sp. (Cat. No. 458/466).

FIGURE 6. SEM images of ossicles from the tentacles of the holotype Psolidium kharlamenkoi n. sp. (SEM) (Cat. No. 458/466).

FIGURE 7. Line drawings of ossicles from the introvert of the holotype Psolidium kharlamenkoi n. sp. (Cat. No. 458/466).

FIGURE 8. Light microscope photographs of ossicles from the dorsal body wall of the holotype Psolidium kharlamenkoi n. sp. (Cat. No. 458/466). A—scales, B—globules, C—perforated plate.

FIGURE 9. SEM images of ossicles from the dorsal body wall of the holotype Psolidium kharlamenkoi n. sp. (SEM) (Cat. No. 458/466). A—scale, B—globule.

FIGURE 10. External view of the paratypes of Psolidium kharlamenkoi n. sp. (Photo by K.E. Sanamyan). A—Cat. No. 457/465-1, side view; B—Cat. No. 457/465-2, side view; C—Cat. No. 191/358, side view; D—Cat. No. 191/358, ventral view.

FIGURE 11. External view of small specimens of Psolidium kharlamenkoi n. sp. (Cat. No. 90/315, photo by K.E. Sanamyan). A—side view, B—top view.

FIGURE 12. Line drawings of ossicles of small specimens of Psolidium kharlamenkoi n. sp. (Cat. No. 90/315). A—ossicles of ventral body wall, B—end plates of tube feet.

FIGURE 13. Collection localities for Psolidium kharlamenkoi n. sp.