Parastichopus regalis ( Cuvier, 1817 )

Khodja, Ihcene, Mezali, Karim & Thandar, Ahmed S., 2021, Multiple records and polymorphism of Parastichopus regalis (Cuvier, 1817) (Echinodermata: Holothuroidea: Stichopodidae) along the Algerian coast, Zootaxa 5032 (4), pp. 549-562 : 552

Parastichopus regalis ( Cuvier, 1817) non-spotted morph

Figures 2–3 , Table 2

Pudendum regale Cuvier, 1817: 22 .

Holothuria triquetra Delle Chiaje, 1828: 71 ; Delle Chiaje, 1841: 4.

Holothuria regalis Grube, 1840: 33 ; Sars, 1859: 96–98, Figures 78–81.

Stichopus regalis Selenka, 1867: 317 ; Koehler, 1921: 182, Figure 138; 1927: 237, Figure 24; Théel, 1886: 194; Marenzeller, 1893: 15; Mortensen, 1927: 391; Cattaneo, 1981: 15; Peres & Picard, 1964: 91–92, 104, 116; Clark, 1922: 63, plate 1, Figures 17–18; Deichmann, 1940: 193, plate 32, Figures 1 –8.

Eostichopus regalis Cutress & Miller, 1982: 720 .

Parastichopus regalis Rowe unpublished data (Worms 2020).

Material examined. LPVCMRMS2019.301; LPVCMRMS2019.302; LPVCMRMS2019.303; LPVC- MRMS2019.304 , Mostaganem, Algeria, 36° 05.077’ N, 00° 00.490’ E, 225 m, 03 June 2019 , 4 specs. LPVC- MRMS2019.308 , Mostaganem, Algeria, 36° 02.611’ N, 00° 01.823’ W, 117 m, 03 June 2019, 1 spec. LPVC- MRMS2019.309 , Mostaganem, Algeria, 35° 59.109’ N, 00° 01.089’ E, 68 m, 03 June 2019, 1 spec.

Description Body length 10.50–20.50 cm, contracted width 3–5.90 cm, weight 6.34–71.24 g. Body soft, body fairly depressed, trivium flattened, sole like, bivium arched, both separated by a distinct lateral fold on each side bearing large papillae. Dorsal surface ( Figure 2A ) reddish-brown, characterized by evenly distributed white conical papillae. Ventral surface ( Figure 2B ) with several rows of podia arranged in three distinct zones, two outer zones whitish brown in colour and mid-ventral one bright red colour forming a distinct groove. Mouth ventral, surrounded by 20 peltate tentacles arranged in two circles; internal and external ( Figure 2C ). Anus terminal. Mouth and anus each bordered by two papillae (about 1 cm), larger than those of the general body wall ( Figure 2D 1 ). Small black spots, each about 1 mm in diameter, cover the both dorsal and ventral surfaces. Thickness of the dorsal integument 1.69–4.74 mm and that of the ventral integument 1–5.01 mm. Calcareous ring delicate, average diameter 10.65 mm. Longitudinal muscles flat, attached to body wall, paired, each about 5.66 mm thick, whitish in life but changing to cream in alcohol, thin at point of insertion to the calcareous ring. Cuvierian tubules absent. Tentacle ampullae about 1.10 to 13 mm ( Figure 2E2 ) in length ( Table 2). Polian vesicle ( Figure 2E 3 ) single, mean length about 19.23 mm, arising from water vascular ring ( Figure 2F ) ventrally. Stone canal also single, mean length 9.68 mm, arising from water vascular ring dorsally; madreporite spherical, attached to dorsal body wall ( Figure 2G 4 ). Gonadal tubules thin, white, in two tufts, one on each side of dorsal mesentery ( Figure 2H ). Dissected specimen, based on microscopic observations of the gonad; determined to be a mature female at stage IV of development.

Ossicles. Ossicles of the anal region ( Figure 3A ), dorsal surface ( Figure 3B ) and ventral surface ( Figure 3C ) appear identical and include only tables. Tables ( Figures 3 Aa; 3Ba; 3Ca) appear more or less symmetrical, disc flat, perforated by 3–6 central holes (4 holed ones most abundant), and 20–60 marginal holes; disc margin smooth; mean diam. of disc, 99.667 µm and mean area 7571.660 µm². Spire 4-pillared ( Figure 3 Ac), about 67.521 µm high, tapered at end, and with 3–4 cross-bars. Rods of papillae and pedicels ( Figures 3 Ab; 3Bb; 3Cb) appear straight or curved, smooth or spiny, with an enlarged, perforated, central part and slightly expanded perforated ends; mean length 222.837 µm. Anal region comprises also plates ( Figure 3 Ad). End plates of pedicels complete or reduced ( Figure 3 Cc), the former oval to irregular, the latter rounded, slightly concave medially, all plates with small holes, the medial holes the largest; smaller plates average 146.424 µm in length, 86.150 µm in width; average diameter of circular plates 209.472 µm. Tentacles ( Figure 3D ) present three types of rods; elongated ( Figure 3 Da), arched ( Figure 3 Db) and robust, branched type with perforated ends ( Figure 3 Dc). Cloaca ( Figure 3E ) possesses dichotomous branched rods.

Figures

FIGURE 1. Sampling stations of Parastichopus regalis along the Algerian coast (the numbered circles represent the sampled stations - see Table 1 for details of the stations).

FIGURE 2. Morphological characters of non-spotted P. regalis. A. Dorsal view. B. Ventral view. C. Arrangement of tentacles in two circles (indicated by the dotted circles). D. 1. Larger papillae on either side of mouth. E. 2. Tentacle ampullae. E. 3. Polian vesicle. F. Calcareous ring (R: Radial and IR: Interradial plates). G. 4. Stone canal (SC) and madreporite (M). H. Gonadal tubules. Scale bar = 1 cm.

FIGURE 3. Ossicles of P. regalis (non-spotted) from different parts of the body. A. Anal region. a. Tables. b. Rods. c. Spires of the tables. d. Plates. B. Dorsal surface and papillae. a. Tables. b. Rods. C. Ventral surface and tube feet. a. Tables. b. Rods. c. End plates. D. Tentacles. a. Elongated rods. b. Arched rods. c. Branched rods. E. Cloaca. Scale bar = 100 µm.

FIGURE 4. Morphological characters of spotted P. regalis. A. Dorsal view, blotches indicated by arrows (1). B. Ventral view spotted individual (note no blotches). C. Degradation of the dermis after 2 hours (individual not immediately preserved in ethanol). Scale bar = 1 cm.