Multiple records and polymorphism of Parastichopus regalis (Cuvier, 1817) (Echinodermata: Holothuroidea: Stichopodidae) along the Algerian coast Author Khodja, Ihcene 0000-0003-3905-974X Protection, Valorization of Coastal Marine Resources and Molecular Systematics Laboratory (PVCMRMS), Department of Marine Science and Aquaculture. Faculty of Natural Sciences and Life. Abdelhamid Ibn Badis University-Mostaganem, PO Box 227, Route nationale N ° 11, Kharrouba, 27000, Mostaganem, Algeria. & ihcene. khodja. etu @ univ-mosta. dz; https: // orcid. org / 0000 - 0003 - 3905 - 974 X ihcene.khodja.etu@univ-mosta.dz Author Mezali, Karim Protection, Valorization of Coastal Marine Resources and Molecular Systematics Laboratory (PVCMRMS), Department of Marine Science and Aquaculture. Faculty of Natural Sciences and Life. Abdelhamid Ibn Badis University-Mostaganem, PO Box 227, Route nationale N ° 11, Kharrouba, 27000, Mostaganem, Algeria. Author Thandar, Ahmed S. School of Life Sciences, University of KwaZulu-Natal, P / Bag X 54001, Durban 4000, South Africa. text Zootaxa 2021 2021-09-09 5032 4 549 562 journal article 10.11646/zootaxa.5032.4.5 1175-5326 5497117 E84B3D64-EDE7-4143-B65F-8BAED6AD4744 Parastichopus regalis ( Cuvier, 1817 ) spotted morph Figures 4–5 , Table 2 Material examined. LPVCMRMS2019.305; LPVCMRMS2019.306, Mostaganem , Algeria , 36° 05.077’ N , 00° 00.490’ E , 225 m , 03 June 2019 , 2 specs. LPVCMRMS2019.307, Mostaganem , Algeria , 36° 02.611’ N , 00° 01.823’ O , 117 m , 03 June 2019 , 1 spec. LPVCMRMS2019.311; LPVCMRMS2019.312, Bouzedjar , Algeria , 35° 38.068’ N , 01° 08.766’ O , 96 m , 04 June 2019 , 2 specs. LPVCMRMS2019.310, Arzew , Algeria , 35° 55.444’ N , 00° 00.490’ E , 77 m , 04 June 2019 , 1 spec. Description. Specimens ( Figures 4A and 4B ) preserved length 14–24.90 cm , contracted width 4–7.50 cm ; total weight 25.07–143.50 g . Each with 5–7 brownish to dark red blotches on the bivium when alive ( Figure 4A 1 ) disappearing after storage in ethanol. Morphological characters similar to non-spotted specimens described above. Dorsal body wall 1.23–6.19 mm thick; ventral body wall 1.22–6.77 mm thick. Polian vesicle single, average length 17.57 mm ; stone canal also single, average length about 10.71 mm . Calcareous ring about 13 mm in diameter. Longitudinal muscles flat, attached to body wall, about 6.75 mm in thickness ( Table 2 ). Ossicles. Anal region ( Figure 5A ), dorsal ( Figure 5B ) and ventral surfaces ( Figure 5C ) present the same type of ossicles as non-spotted specimens. Table discs ( Figures 5 Aa; 5Ba; 5Ca) 97.926 µm in average diameter and 7099.090 µm ² in total area. Spire 4-pillared, about 67.521 µm high, 64.691 µm wide, with 3–4 cross-bars. Papillae and pedicels include perforated rods ( Figures 5 Ab; 5Bb; 5Cb) as in the non-spotted morph, 265.026 µm in average length. Complete pedicel end plates ( Figure 5 Cc) circular, average diameter 439.218 µm; oval end plates 197.766 µm in mean length and 84.328 µm in mean width. Cloaca ( Figure 5D ) presents dichotomously branched rods. Tentacle rods ( Figure 5E ) elongated ( Figure 5 Ea), or arched ( Figure 5 Ec), branched ( Figure 5 Eb) and dichotomously branched rods ( Figure 5 Ed). 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. TABLE 2. Morphological and anatomical characters of the two morphotypes of P. regalis (non-spotted and spotted).

Morphotype	Non-spotted	Spotted
Morphological characters
Ventral body shape	sole like
Contracted length (cm)	10.50–20.50	14–24.90
Contracted width (cm)	3–5.90	4–7.50
Consistency of body wall	soft, gelatinous
Total weight (g)	9.34–71.24	25.07–143.50
Dorsal body wall thickness (mm)	1.69–4.74	1.23–6.19
Ventral body wall thickness (mm)	1–5.01	1.22–6.77
Colour of the trivium	brown and bright red in the center
Colour of the papillae	White
Shape of the bivium	Arched
Colour of the bivium	reddish brown	reddish brown with 5–7 dark blotches
Disposition of the pedicels (bivium)	In more of less regular rows
Position of the mouth	Ventral
Position of the anus	Terminal
Number of tentacles	20	20
Internal characters (mm)
Tentacle ampullae length	1.10–13	5.94–13
Polian vesicle length	12.54–25.19	12.53–21.69
Stone canal length	6.97–13	8.12–12.37
Shape of the madreporite	Spherical
Longitudinal muscles edges	Flat, attached
Average width of longitudinal muscles	3.39–7.30	4.49–13.79
Diameter of calcareous ring	8.75–12.28	9.28–17.20
Endoskeletal characters mean (µm)
Diameter of table discs	99.668	97.926
Length of perforated rods of papillae and pedicels	222.837	265.026
Length of oval end plates	146.424	197.766
Width of oval end plates	86.150	84.328
Diameter of the complete end plates	209.472	439.218
Length of elongated rods of tentacles	600.410	809.232
Length of arched rods of tentacles	663.903	459.545
Length of branched rods of tentacles	788.369	688.710

Remarks. Both spotted and non-spotted Parastichopus regalis individuals degrade very quickly if they are not immediately preserved in ethanol, after collection. The dermis rapidly disintegrates and the texture of the body becomes gelatinous, spreading out on the support on which the specimen is placed ( Figure 4C ). This reaction is probably due to the stress during fishing operation and/or exposure to light or change in pressure and/or temperature, since fished from waters more than 36 m deep. The ability to lose a piece of dermis from the body wall when in danger has been observed in many holothuroids ( Kropp 1982 ). The use of formalin, although good for fixation, does not allow for better preservation because the body does not keep its original shape and the ossicles tend to corrode rapidly. Hence, alcohol is recommended although the bright red colour of the ventral surface as well as the dark spots on the dorsal surface (when present) do disappear. The thickness of the body wall can vary from one individual to another since the general texture of the body wall is very soft, thus not rigid enough to maintain the original form.