Acryptolaria angulata

Acryptolaria angulata (Bale, 1914) (Figs 1; 30; 31A; Table 2)

Cryptolaria angulata Bale, 1914: 166, 167, pl. 35, fig. 1; 1915: 251. — Stranks 1993: 7.

Acryptolaria angulata – Schuchert 2003: 155, 156, fig. 14. — Peña Cantero et al. 2007: 235-237, figs 2, 17B; tab. II.

Not Acryptolaria angulata – Vervoort 1966: 116, 117, fig. 16 [=? A. rectangularis (Jarvis, 1922)]

Not Acryptolaria angulata – Hirohito 1995: 102, text-fig. 29a, b, pl. 6 fig. B [=? A. bulbosa (Stechow, 1932)]

MATERIAL EXAMINED. — Loyalty Islands. BIOCAL 1, stn CP 84, 20°43.498’- 20°42.948’S, 167°00.278’- 167°01.500’E, 210- 150 m, 6.IX.1985, 5 stems up to 40 mm high with coppinia (MNHN-Hy.2009-0176); 2 slides (MNHN-Hy.2009-0144 & RMNH-Coel. no. 37468, slide 288 with fragments up to 17 mm long). BIOGEOCAL, stn DW 292, 20°28.23’- 20°28.18’S, 166°48.45’- 166°48.48’E, 470- 465 m, 27.IV.1987, a few stems up to 12 mm high (slide MNHN-Hy.2009- 0145). MUSORSTOM 6, stn DW 399, 20°41.80’S, 167°00.20’E, 282 m, 14.II.1989, 1 stem c. 30 mm high (RMNH-Coel. no. 31494); 1 stem c. 23 mm high (RMNH-Coel. no. 35101, slide 662). — Stn DW 474, 21°08.80’S, 167°55.50’E, 260 m, 22.II.1989, 5 stems up to 20 mm high (MNHN-Hy.2009-0177). — Stn DW 487, 21°23.30’S, 167°46.40’E, 500 m, 23.II.1989, several stems up to 25 mm high, on coral (MNHN-Hy.2009-0178); 1 stem c. 33 mm high in slide (MNHN-Hy.2009-0146).— Stn DW 489, 20°48.37’S, 167°05.86’E, 700 m, 24.II.1989, 1 stem c. 62 mm high, with coppinia (MNCN 2.03 /402). 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, 3 stems up to 12 mm high, on coral (RMNH-Coel. no 31495). — Stn DW 44, 22°47.300’- 22°47.350’S, 167°14.300’- 167°14.500’E, 440-450 m, 30.VIII.1985, 1 fragment c. 10 mm long, with coppinia (RMNH-Coel. no. 31496). — Stn DW 51, 23°05.273’- 23°05.432’S, 167°44.951’- 167°45.355’E, 700- 680 m, 31.VIII.1985, 5 stems up to 10 mm high (MNCN 2.03/403). — Stn DW 66, 24°55.435’- 24°54.849’S, 168°21.678’- 168°21.995’E, 515- 505 m, 3.IX.1985, 3 stems up to 37 mm high, with coppinia (MNCN 2.03/404). — 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. 30 mm high, with coppinia (MNHN-Hy.2009- 0179). SMIB 4, stn DW 37, 24°54.5’- 24°53.9’S, 168°22.3’- 168°21.5’E, 515-540 m, 7.III.1989, 1 stem c. 24 mm high, with coppinia (MNHN-Hy.2009-0180). SMIB 5, stn DW 70, 23°40.6’S, 168°01.1’E, 270 m, 7.IX.1989, 1 stem c. 7 mm high and a few fragments up to 20 mm long (RMNH-Coel. no. 31497). — Stn DW 76, 23°41.2’S, 168°00.5’E, 280 m, 7.IX.1989, 1 stem c. 22 mm high (MNHN-Hy.2009-0181). — Stn DW 88, 22°28.6’S, 168°40.2’E, 350 m, 13.IX.1989, 1 stem c. 15 mm high (MNCN 2.03/405). — Stn DW 95, 22°59.7’S, 168°19.8’E, 200 m, 14.IX.1989, 3 stems up to 25 mm high (MNHN-Hy.2009-0182). — Stn DW 101, 23°21.2’S, 168°04.9’E, 270 m, 14.IX.1989, 1 fragment c. 18 mm long (MNCN 2.03/406).

ECOLOGY AND DISTRIBUTION. — Acryptolaria angulata seems to be a bathyal species. It was previously known from depths between 180 m (Bale 1914) and 324 m (Bale 1915); our material was collected at depths from 150 to 965 m, extending considerably the lower limit of its bathymetric range. Schuchert (2003) reported it on bottoms of sandy mud and small stones. Hitherto it was only known from the Great Australian Bight (Bale 1914, 1915) and the Kei Islands, Indonesia (Schuchert 2003). Our material originates from the Loyalty Islands and the Norfolk Ridge areas and was also epibiotic on coral. Coppiniae were found in February, March, August and September.

DESCRIPTION

Polysiphonic stems up to 62 mm high (Fig. 31A), with a variable degree of branching, but up fifth-order branches observed. Usually branching irregular and in one plane, frequently with anastomoses, giving a mesh-shaped appearance to the stems. Branches straight (Fig. 1A).

Hydrothecae alternately arranged and more or less in one plane (Fig. 1A), roughly cylindrical, but with a strongly marked constriction due to a sharp perisarc invagination at about basal third of adcauline wall (Fig. 1 A-F); diameter also decreasing at basal part. Hydrotheca curved twice: strongly outwards at distal part of adnate portion, becoming approximately perpendicular to the adnate part, and slightly or strongly upwards just after the adnate wall becomes free. Abcauline wall with a distinct inflexion point at approximately half its length; in some colonies forming a deep embayment at that point; some hydrothecae may there become collapsed (Fig. 1E, F). Basal part of abcauline wall usually straight, parallel to longitudinal axis of branch; distal part slightly to strongly convex. Adcauline wall broadly convex at adnate part and concave at free portion. Adcauline wall adnate over half its length (adnate/free ratio 1.6). Hydrotheca with a strongly marked, basal ring of desmocytes (Fig. 1C, D, F). Hydrothecal aperture circular, oblique, upwardly directed at a varied degree (35-75°). Rim even, sometimes with short renovations.

Large nematocysts very abundant, relatively small, ovoid (Fig. 30) and provided with a lateral opening.

Gonothecae set into a coppinia deprived of defensive tubes (Fig. 1I, G), bottle-shaped, with a distal neck (Fig. 1I, J). Gonothecal diameter gently increasing from base to distal neck where the diameter strongly decreases. In the material from SMIB 4 stn DW 37 the gonothecae are closely grouped, forming a tight mosaic in dorsal view (Fig. 1G), and provided with a short neck with a wide aperture (Fig. 1H). In the material from BIOCAL 1 stn CP 84, the gonothecae have a longer neck (Fig. 1J), with a slightly smaller distal aperture. Some gonothecae with renovations of the rim (Fig. 1I).

REMARKS

The degree of branching is varied; for example, in the material from BIOCAL 1 stn CP 84 the stems are much branched, with up to fifth-order branches observed, whereas in the material from SMIB 4 stn DW 37, only secondary branches are present.

The type material of Acryptolaria angulata was recently examined by Peña Cantero et al. (2007) who established the differences with the related species (i.e. A. bulbosa and A. rectangularis) (see Peña Cantero et al. 2007 for a fuller discussion). This material consisted of microslide preparations, which made it difficult to find nematocysts of which only inaccurate measurement could be taken; however, a few large nematocysts could then be observed. Through the study of our material it has also been confirmed the presence of the small-group nematocysts in this species.

The present material allowed a more precise characterization of Bale’s species, as well as the description of the unknown coppinia. Acryptolaria angulata is identifiable by the shape of the hydrotheca with its characteristic sharp perisarc invagination at about the basal third of its adcauline wall. The hydrothecal abcauline embayment has a varied development. In some hydrothecae it is just slightly appreciable (Fig. 1A, D), whereas in others there is a deep invagination (Fig. 1B, C). On the other hand, there are hydrothecae in which the deep embayment may be more or less closed, the two parts of the abcauline wall come in close contact and even become fused (Fig. 1E, F). This also happens in other species of the genus (cf. A. bulbosa and A. inversa n. sp.).

Notwithstanding the amazing variation in the size of the hydrothecae, we are apparently dealing with a single species, because there is an almost complete gradual overlap. Furthermore, there are no differences in the nematocysts of the larger size class. The differences in the shape of the gonothecae between the material from SMIB 4 stn DW 37 and BIOCAL 1 stn CP 84 could be due to sexual dimorphism.