Acryptolaria pseudoangulata n. sp.

(Figs 24; 30; 32G; Table 25)

TYPE MATERIAL. — NW New Caledonia. MUSORSTOM 4, stn CP 217, 23°03.6’S, 167°27.0’E, 850 m, 29.IX.1985, many stems up to 30 mm high, with coppinia (5 c. 25 mm high stems with coppinia from communal stolonal mass, holotype, MNHN-Hy.2009-0171; several stems on gorgonid, paratype, RMNH-Coel. no. 31524; several stems on gorgonid, paratype, MNCN 2.03 /431) .

OTHER MATERIAL EXAMINED. — NW New Caledonia. MUSORSTOM 4, stn CP 180, 18°56.8’S, 163°17.7’E, 450 m, 18.IX.1985, 1 fragment c. 12 mm long (MNHN-Hy.2009-0213). — Stn CP 194, 18°52.8’S, 163°21.7’E, 550 m, 19.IX.1985, many stems up to 40 mm high, on sponge (RMNH-Coel. no. 31525).

Loyalty Islands. BIOGEOCAL, stn CP 297, 20°38.64’- 20°38.67’S, 167°10.77’- 167°11.07’E, 1230-1240 m, 28.IV.1987, 6 stems up to 100 mm high, on coral (MNHN-Hy.2009-0208). — Stn DW 307, 20°35.38’- 20°35.32’S, 166°55.25’- 166°55.33’E, 470-480 m, 1.V.1987, 1 fragment c. 11 mm long (MNHN-Hy.2009- 0209).

Norfolk Ridge. BIOCAL 1, stn DW 36, 23°08.647’- 23°08.900’S, 167°10.994’- 167°11.296’E, 650-680 m, 29.VIII.1985, 6 stems up to 25 mm high, on coral (MNCN 2.03/432). — Stn DW 66, 24°55.435’- 24°54.849’S, 168°21.678’- 168°21.995’E, 515- 505 m, 3.IX.1985, a few stems up to 23 mm high, on coral (MNHN-Hy.2009-0210). — Stn DW 70, 23°24.700’- 23°25.650’S, 167°53.650’- 167°52.700’E, 965 m, 4.IX.1985, 1 stem c. 29 mm high (MNCN 2.03/433). SMIB 4, stn DW 36, 24°55.6’- 24°54.9’S, 168°21.7’- 168°21.7’E, 500-530 m, 7.III.1989, 1 fragment c. 13 mm long and 2 stems up to 24 mm (MNHN-Hy.2009- 0211). — Stn DW 37, 24°54.5’- 24°53.9’S, 168°22.3’- 168°21.5’E, 515-540 m, 7.III.1989, 4 stems up to 21 mm high, on coral (MNCN 2.03/434). — Stn DW 39, 24°56.2’- 24°55.4’S, 168°21.5’- 168°21.5’E, 525-560 m, 7.III.1989, 5 stems up to 25 mm high (RMNH-Coel. no. 31526).

Chesterfield Islands. MUSORSTOM 5, stn CP 293, 23°09.35’S, 159°30.80’E, 280 m, 11.X.1986, 1 stem c. 12 mm high (RMNH-Coel. no. 35441, slide 1687).

ETYMOLOGY. — The specific name pseudoangulata refers to the fact that in this species the shape of the hydrothecae reminds that of A. angulata; the species name is an adjective corresponding in gender with the (feminine) genus name.

ECOLOGY AND DISTRIBUTION. — Acryptolaria pseudoangulata n. sp. seems to be a bathyal species, having been collected at depths between 280 and 1240 m. It was found at the Chesterfield Islands, at the Loyalty Islands, in the Norfolk Rigde area and off NW New Caledonia. It lives epibiotic on coral and sponges. Coppinia was found in September.

DESCRIPTION

Stems up to 100 mm high, but usually much smaller (Fig. 32G). Branching irregular but approximately in one plane. Degree of branching variable, from scarcely branched stems with just a few primary branches to abundantly branched stems with up to third-order branches. Branches slightly geniculate (Fig. 24A), sometimes with anastomoses.

Hydrothecae approximately in one plane (Fig. 24A, B) and with a double curvature (Fig. 24 A-D): strongly curved outwards where they become free, being roughly perpendicular to adnate portion, and then curving markedly upwards; some of the longer hydrothecae may present a third slight outward bend (Fig. 24D). Hydrothecal diameter increasing distally in free part; maximum diameter at aperture, minimal diameter at base and at the point where the hydrotheca becomes free. Hydrotheca adnate for less than half of its adcauline length (adnate/free ratio 0.9). Adnate part of adcauline wall convex or with a shallow invagination in the middle of its length. Abcauline wall straight or convex in its basal part; after the inflection point, first convex and then straight. Hydrothecal aperture circular, oblique and directed upwards, forming an angle of c. 40° with long axis of branch. Hydrotheca usually with a few renovations (Fig. 24A, B, D).

Large nematocysts relatively very small and ovoid (Fig. 30).

Gonothecae set into a coppinia with an external fence of defensive tubes forming a distally closed, onion-shaped protective structure. Gonothecae set close together (Fig. 24E) in the basal part of the coppinia, but also ascending on part of the defensive tubes (Fig. 24E). Gonothecae long and thin, with an unconspicuous distal neck with a circular aperture. Planulae completing development outside gonothecae, in the breeding chamber formed by defensive tubes.

REMARKS

Acryptolaria pseudoangulata n. sp. comes close to A. angulata in the general shape of the hydrothecae, but a detailed examination shows that they are different since in A. pseudoangulata n. sp. the hydrotheca lacks the characteristic invagination of the adnate adcauline wall present in A. angulata . Moreover, in the latter the branches are straight, the nematocysts are larger (15.9 × 8.6 µm) and the hydrothecae are adnate for half of the adcauline length or more. Both species also differ in the structure of the coppinia because in A. angulata the coppinia is deprived of defensive tubes, whereas in A. pseudoangulata n. sp. there are defensive tubes forming a protective envelope.

Acryptolaria pseudoangulata n. sp. is also similar to A. rectangularis (Jarvis, 1922) . Unfortunately, Jarvis’s species is poorly known and there is no information concerning the cnidome, which makes it difficult to assign additional specimens to this species. Peña Cantero et al. (2007) could not examine type material of this species whose location, according to Vervoort & Watson (2003), is unknown. Anyway, Peña Cantero et al. (2007) provided a lengthy discussion of Jarvis’s species and of the related A. angulata and A. bulbosa .

Acryptolaria pseudoangulata n. sp. resembles A. rectangularis in the general shape of the hydrothecae, but we believe they are different species unless the redescription of the unlocated type material of the latter proves the contrary. According to Jarvis’s (1922) figures, the branches have a distinct zigzag arrangement, whereas in A. pseudoangulata n. sp. the branches only are slightly geniculate or straight. Jarvis (1922), when comparing its species with A. angulata, made it clear that A. rectangularis is characterized by “the straightness of the upper wall of the hydrotheca in its divergent portion”. In A. pseudoangulata n. sp. the hydrotheca has a double curvature, being strongly curved outwards where it becomes free of the axis, where it is roughly perpendicular to the adnate portion (just as in A. rectangularis), but farther on it is markedly bent upwards (contrary to the “straightness” of A. rectangularis). Moreover, some longer hydrothecae may even present a third slight bend outwards (Fig. 24D). In addition, the hydrothecae are much longer in A. pseudoangulata n. sp. In A. rectangularis the diameter at the adnate part of the hydrotheca gradually disminishes basally, being almost fusiform, but that diameter distinctly increases in the basal, adnate part of the hydrotheca of A. pseudoangulata n. sp. past a narrowed part of variable extension, which forms a slight concavity (cf. Fig. 24C, D); later the diameter sharply decreases again at the hydrothecal base.