Actinopyga caerulea, Samyn, Yves, Vandenspiegel, Didier & Massin, Claude, 2006

Samyn, Yves, Vandenspiegel, Didier & Massin, Claude, 2006, A new Indo­West Pacific species of Actinopyga (Holothuroidea: Aspidochirotida: Holothuriidae), Zootaxa 1138, pp. 53-68 : 58-66

Actinopyga caerulea sp. nov.

( Figures 1 A–J, 2A–E, 3A–E, 4A–G, 5; plate 1A–C)

Actinopyga crassa ; Cherbonnier & Féral 1984: 664, fig. 3 A–K; Féral & Cherbonnier 1986: 70 –71; Erhardt & Moosleitner 1995: 1153 (non A. crassa Panning, 1944 )

Actinopyga (?) bannwarthi ; Erhardt & Baensch 1998: 1076 (non A. bannwarthi Panning 1944 )

Name­bearing types

Holotype, RMCA 1803; Paratype 1, CNDRS 2004.09; Paratype 2, RBINS IG 30376; Paratype 3, MNHN EcHo 8081; Paratype 4, NHM 2005.2405.

Material examined

Union des Comores (Grande Comore, Ikoni), 22.XI. 2003, 37 m depth, coll. Y. Samyn & D. VandenSpiegel, RMCA 1803 (holotype); Union des Comores (Grande Comore, H.L.M Langouste), 11.X. 2004, 28 m depth, coll. Y. Samyn, D. VandenSpiegel & C. Massin, CNDRS 2004.09 (paratype 1); Union des Comores (Grande Comore, Itsandra), 20.XI. 2003, 23 m depth, coll. Y. Samyn & D. VandenSpiegel, RBINS IG 30376 (paratype 2); Union des Comores (Grande Comore, Aérodrome), 16.V. 2005, 26 m depth, coll. Y. Samyn & D. VandenSpiegel, NMHN EcHo 8081 (paratype 3); Union des Comores (Grande Comore, Itsandra), 16.V. 2005, 21 m depth, coll. Yves Samyn & D. VandenSpiegel, NHM 2005.2405 (paratype 4); Papua New Guinea (Madang Province, Madang’s Reef, Wongat Island), 05.X. 1996, 25 m depth, coll. C. Massin, RBINS, IG 28 455/22.

Type locality

Union des Comores, Grande Comore, Ikoni.

Type material (2 syntypes) of Actinopyga serratidens var. bannwarthi Panning, 1944 : ZMH E5902 (Zoologishes Institut und Zoologisches Museum der Universität Hamburg); Egypt (Suez), 1913, depth unknown, coll. Dr E. Bannwarth.

Non type material (1 specimen) of A. mauritiana ( Quoy & Gaimard, 1833) (misidentified as A. bannwarthi Panning, 1944 by Cherbonnier (1988)): Madagascar ( Nosy Be, Andilana), 20.VIII.1959, coll. G. Cherbonnier, EcHh 5082 (Muséum National d’Histoire Naturelle, Paris, France).

Non type material (2 specimens) of A. crassa Panning, 1944 : Seychelles ( Mahé), 07.IX.1969, coll. Mission zoologique MRAC­ULB, RMCA 1186.

Description

Very large species; living specimens up to 400 mm long and 140 mm wide mid­body; preserved specimens from 225 to 280 mm long and from 85 to 110 mm wide mid­body. Body loaf­shaped with slight ventral flattening (more or less cylindrical with some distal tapering). Colour in life bluish with patches of white devoid of tube feet at anterior and posterior ends and, discontinuously, along sides (Plate 1). Colour in type material in alcohol largely preserved, but faded to dull brown in specimen from Papua New Guinea. White patches remain clearly visible on all specimens. Body wall smooth, up to 14 mm thick. Mouth ventral, surrounded by 15–18 large, peltate, uniformly bluish­grey tentacles, in turn surrounded by a stout collar of bluish papillae, fused at their base. Anus terminal, guarded by five prominent, calcareous, teeth, each bearing numerous tubercles. Ventral tube feet stout, distributed unevenly, albeit somewhat concentrated in ambulacral areas. Dorsal “papillae” large, conical at base, near cylindrical at top; bluish at base, slightly lighter at top; scattered over ambulacral and interambulacral areas, though absent in white zones. Cuvierian organ absent. Single, club­shaped Polian vesicle, about one seventh of length of preserved animals. Stone canal and associated madreporite not observed in all the specimens studied. Gonad observed only in the specimen from Papua New Guinea. Calcareous ring huge, radial pieces about twice as large as interradial pieces ( Figure 1 A). Details of surface of calcareous ring obscured by thick layer of tissue.

Ossicles: Tentacles with rods only; base of tentacles with few, straight to slightly curved, smooth rods, 50–90 m long ( Figure 1 B); tip of tentacles with similar but larger rods, up to 500 m long ( Figure 1 C, D), occasionally distally branching ( Figures 1 C, 3A). Ventral body wall with rosettes of various forms, some elongated with endings swollen, others wider and more spiny, 15–65 m long ( Figures 1 E, 3B). Dorsal body wall with small rosettes that have their endings swollen, 20–60 m long ( Figures 1 F, 3C) and elongated rod­like spiny rosettes, 255– 100 m long ( Figures 1 G, 3D). The proportion of rosettes with swollen endings versus spiny rod­like rosettes as well as the size of the rosettes are highly variable within a single specimen, depending on site of bivium sampled. The same phenomenon occurs in specimens coming from different geographic localities: holotype from Comoros Islands with more spiny ossicles in dorsal body wall than the specimen from Papua New Guinea. Base of dorsal papillae with rosettes and rodlike rosettes, 25–65 m long, as well as dichotomously branched spiny rods, 100–160 m long ( Figures 1 J, 3E). Tip of dorsal papillae with spiny rods of various form; from simple to complex branching, 50–200 m long ( Figures 1 H, 4A). Ventral tube feet with smooth rods, 25–40 m long, spiny rods, 40–150 m long, and stout spiny rods, 100–140 m long, with perforated extremities ( Figures 2 A, 4B); terminal disc, up to 1,000 m across, composed of several pieces; centrally several perforated plates with large holes ( Figure 4 C) surrounded by 10–12 perforated plates with smallest holes at periphery ( Figure 4 D). Cloaca with spiky rods, similar in shape as those from dorsal papillae, 50–100 m long ( Figures 2 D, 4E). Longitudinal and cloacal retractor muscles with simple, smooth, occasionally branched rods, 35–55 m long ( Figures 2 B, C, 4F, G). Gonad with spiny, branched rods, 160–250 m long ( Figure 2 E).

Etymology

The name caerulea, Latin , refers to the unique blue colour of the species.

Ecology

This species is characteristic of somewhat deeper tropical waters; it has been observed from 12 to 45 m. The species is predominantly a detritus/deposit feeder on coral patches on the outer slope of coral reefs; it forages actively during the day.

PLATE 1. Actinopyga caerulea sp. nov. as photographed in situ in Comoros (A), Sulawesi (B), Bali (C) and Papua New Guinee (D). (Picture A by D. VandenSpiegel; B by D. Lane; C by R. Myers and D by P. Colins).

Geographic distribution

Tropical Indo­Pacific; confirmed sightings have been made in Thailand (see Erhardt & Moosleitner 1995, as A. crassa ), the Philippines (see Erhardt & Baensch 1998, as A. (?) bannwarthi ), Indonesia [Bali (Myers pers. comm.) and Sulawesi (Lane pers. comm.)], Papua New Guinea [Kavieng (Colin pers. comm), Hansa Bay (Colin pers. comm.) and Madang (present paper)], New Caledonia (see Féral & Cherbonnier 1986, as A. crassa ) and the Archipelago of the Comoros (type locality). Figure 5 shows the known distribution of this species, including locations requiring confirmation of identification.

Discussion

Actinopyga caerulea sp.nov belongs to what Panning (1944) has termed the ‘ echinites group. It shares with A. bannwarthi the presence of spiny rosettes (cf. Panning 1944, Fig. 22, p. 54). However, rosettes from A. bannwarthi are less spiny and have many more lateral extensions than those from A. caerulea . Another striking difference between the two species lies in the colouration: the two syntypes of A. bannwarthi are uniform dark chocolate brown dorsally ( Figure 6 A) and light brown to yellow ventrally ( Figure 6 B), with no white patches devoid of tube feet on the lateral and dorsal surfaces of the body. The two species differ also in terms of distribution: A. caerulea has not yet been found in the Red Sea, whereas A. bannwarthi seems restricted to it. Sloan et al. (1979, as A. sp. cf. A. bannwarthi ), Cherbonnier (1988) and Rowe & Gates’ (1995) records of A. bannwarthi need verification. Certainly one of the Malagasy specimens identified by Cherbonnier (1988) is A. mauritiana and not A. bannwarthi .

With comparative voucher material now at hand, we conclude that we are not dealing with Actinopyga crassa (see Erhardt & Moosleitner 1995). The latter species differs markedly from A. caerulea in the presence of stout, slightly curved rods in the ventral body wall and in the presence of elongated narrow rod­like rosettes with lateral extensions in the dorsal body wall (cf. Panning 1944, fig 19, p. 51).

The more recently described A. flammea also appears to belong to Panning’s (1944) ‘ echinites group’, an observation we share with Cherbonnier (1979). Nevertheless, A. caerulea can again be easily distinguished from A. flammea , in life, because A. caerulea has a conspicuous bluish and white colouration, and A. flammea has a uniformly brick red body wall and prominent, greyish, tubercular “papillae”. Further, A. caerulea differs markedly from A. flammea in not having closed rosettes in the ventral body wall (see Cherbonnier 1979, fig. 2F,G, p. 5).

Our observation of a compound endplate in the ventral tube feet is not new. This character has already been noted for several species in Actinopyga , Bohadschia , Pearsonothuria graeffei ( Semper, 1868) , as well as in certain Stichopodidae ( Massin 1996; 1999; unpublished data) and Synallactidae , notably species of Synallactes Ludwig, 1894 ( Massin, 1992) . More detailed systematic study of such “fragmentation” in all the genera of Aspidochirotida will help to determine whether this phenomenon is due to common descent or not. For now, we can note that an endplate of a large diameter (500 m across) does not ipso facto imply that the endplate will be compound. Indeed, some aspidochirotid species have a simple, single endplate of over 500 m across, while others possess a compound endplate that is 350 m across.

Figures

FIGURE 1. Actinopyga caerulea sp. nov. (Papua New Guinea). A, Calcareous ring,: r = radial piece, ir = interradial piece. B, Rods from base of tentacles. C, D Rods from tip of tentacle. E, Rosettes from ventral body wall. F, Rosettes from dorsal body wall. G, Elongated rod­like rosettes from dorsal body wall. H, Rosettes from tip of dorsal papillae. J, Rods from base of dorsal papillae.

FIGURE 2. Actinopyga caerulea sp. nov. (Papua New Guinea) A, Rods from ventral tube feet. B, Rods from longitudinal muscle. C, Rods from cloacal retractor muscles. D, Rods from cloacal wall. E, Rods from gonad.

FIGURE 4. Actinopyga caerulea sp. nov. (Comoros, holotype) A, Rods from tip of dorsal papillae. B, Rods from ventral tube feet. C, Central plate from fragmented terminal disc. D, In toto view of fragmented terminal disc. E, Spiny rods from cloacal wall. F, Rods from cloacal retractor muscle. G, Rods from longitudinal muscle. Scale A & F = 50 m; Scale B, E, G = 10 m; Scale C = 100 m; Scale D = 200 m.

FIGURE 5. Actinopyga caerulea sp. nov. Known geographic distribution with uncertain records flagged with a question mark.

FIGURE 6. One of the two syntypes of A. bannwarthi Panning, 1944 as deposited in the ZMH (ZMH E. 5902) (A) dorsal view, (B) ventral view.