Holothuria (Panningothuria) forskali Delle Chiaje, 1823

Madeira, Patrícia, Kroh, Andreas, Cordeiro, Ricardo, De, António M., Martins, Frias & Ávila, Sérgio P., 2019, The Echinoderm Fauna of the Azores (NE Atlantic Ocean), Zootaxa 4639 (1), pp. 1-231 : 149-150

Holothuria (Panningothuria) forskali Delle Chiaje, 1823

( Fig. 35 )

Reports for the Azores:

Holothuria forskali Delle Chiaje, 1823 — $ Marques 1983: 4, fig. 6; Pereira 1997: 333; $ Morton et al. 1998: 98, 169, figs. 5.2T, 8.8R; Micael & Costa 2010: 323; Micael et al. 2012: 4.

See: Koehler (1921b: 179–180, fig. 135); O’Loughlin et al. (2007).

Occurrence: Mediterranean Sea and northeast Atlantic, from Scandinavia south to the coast of Morocco ( Hérouard 1929, Tortonese 1965, Rowe 1969), including the Azores ( Marques 1983), Madeira ( Bianchi et al. 1998) and Canaries ( Pérez-Ruzafa et al. 1992b).

Depth: 0–850 m ( Koehler 1921 b, Mecho et al. 2014); AZO: 0–12 m (herein).

Habitat: soft to hard substrata and among algae and seagrass beds ( Pérez-Ruzafa et al. 1992 b, Morton et al. 1998).

Larval stage: probably planktotrophic (inferred from the genus, see McEdward & Miner 2001).

Material examined: DBUA-ECH 392 (in front of the Marina, Ponta Delgada , SMG, AZO, c. 39°00’44”N, 27°57’28”W, 1997.04. 18, 12 m; 1 spm, TL = 82 mm); DBUA-ECH 393 (Cerco, Caloura, SMG, AZO, 37°42’26”N, 25°30’37”W, 1996.07.13, intertidal; 1 specimen, TL = 92 mm); DBUA-ECH 398 [Capelas (Morro), SMG, AZO, c. 37°50’37”N, 25°41’18”W, 1996.05. 26, 9 m; 1 spm, TL = 165 mm]; DBUA-ECH 434 (Horta harbour, FAY, AZO, c. 38°31’51”N, 28°37’23”W, 2011.03. 11, 6 m; 1 spm, TL = 65 mm).

Description: body almost cylindrical, flattened ventrally. Body wall relatively thick. Epidermis smooth and very delicate. Mouth subventral surrounded by a crown of 20 peltate tentacles (cauliflower-like). Well-developed conical papillae irregularly arranged dorsally and laterally; presence of a collar of small oral papillae. Ventral surface with numerous tube feet in four rows. Well developed Cuvierian tubules. Calcareous deposits scarce, mostly composed of much reduced tables (<50 μm) with four holes; buttons absent; tube-feet and papillae also with elongate, irregularly branched rods; the tentacles with curved rods. Colour (in ethanol): solid deep brown to black bivium (papillae the same colour as the body) and trivium slightly lighter. Colour (in vivo; DBUA-ECH 434): body deep brown with or without white papillae tips.

Remarks: Holothuria forskali can be distinguished in situ based on gross morphology characters, such as the very dark brown to black body colour with white papillae (although not always visible) and the presence of well developed Cuvierian tubules ( Koehler 1921b). In the Azores, neither the dark colour nor the presence of Cuvierian tubules are exclusive to this sea cucumber. Holothuria sanctori , which is known as well to eject Cuvierian tubules if disturbed, shows an extraordinary degree of variability in its colour pattern: from dark brown or black body to a blackish ventral surface with an almost bright yellow dorsum on which the yellow rings can become so numerous that it is hard to perceive the dark background ( Fig. 36 ). Intermediate colour forms in H. sanctori can present less conspicuous yellow (almost white) rings that could be confused with the white papillae described for H. forskali .

In the characterization of the marine coastal biota of the Azores, Morton et al. (1998) illustrated just two species of sea cucumbers, H. mammata (under the name Holothuria tubulosa ) and H. forskali . They noted that the later species was a conspicuous presence in certain areas, such as tide-pools and marine lagoons. They also added that this species has the particularity of readily ejecting Cuvierian tubules when disturbed. We believe that Morton et al. (1998) may have overlooked the presence of H. sanctori in the studied areas. In the Azores, H. sanctori can be quite abundant in areas of relatively low hydrodynamism, reaching at times spectacular densities like these observed by Pérez-Ruzafa et al. (1992b) for the Canaries.

Figures

FIGURE 35. Holothuria (Panningothuria) forskali Delle Chiaje, 1823 (DBUA-ECH 398: A, B, E; DBUA-ECH 434: C, D). Dorsal view (A); ventral view (B); detail of the papillae (C); specimen, when alive (D); ossicles (E).

FIGURE 36. Holothuria (Platyperona) sanctori Delle Chiaje, 1823 (DBUA-ECH 320: A, B, E; DBUA-ECH 402: C; DBUA- ECH 405: D; DBUA-ECH 398: E). Dorsal view (A, C); ventral view (B); specimen, when alive (D); ossicles (E).