Acryptolaria cf. operculata Stepanjants, 1979

Peña Cantero, Álvaro L. & Vervoort, Willem, 2010, Species of Acryptolaria Norman, 1875 (Cnidaria, Hydrozoa, Lafoeidae) collected in the Western Pacific by various French expeditions, with the description of nineteen new species, Zoosystema 32 (2), pp. 267-332 : 311-312

Acryptolaria cf. operculata Stepanjants, 1979 ( Figs 22 ; 30 ; Table 23)

Acryptolaria operculata Stepanjants, 1979: 52 , pl. 9 fig. 5A, B. — Peña Cantero et al. 2007: 258-261 , figs 12, 16D, 18D, 19E, tab. XII.

Acryptolaria patagonica El Beshbeeshy, 1991: 67-70 , fig. 14.

? Acryptolaria patagonica – Watson 2003: 162, 163, fig. 12A-C. — Vervoort & Watson 2003: 51-53, fig. 7A-G.

MATERIAL EXAMINED. — Norfolk Ridge. BIOCAL 1, 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. 8 mm high and a few stolonal hydrothecae on coral (MNHN-Hy.2009-0207).

CHALCAL 2, stn DW 76, 23°40.50’S, 167°45.20’E, 470 m, 30.X.1986, 1 stem c. 14 mm high (RMNH-Coel. no. 31523).

ECOLOGY AND DISTRIBUTION. — Acryptolaria operculata has been collected from depths between 98 and 980 m (El Beshbeeshy1991).Its confirmed known distribution includes sub-Antarctic waters of the Patagonian shelf ( Stepanjants 1979; El Beshbeeshy 1991). Our material originates from the Norfolk Ridge area where it was collected at depths between 470 and 965 m, living epibiotic on corals.

DESCRIPTION

Stems up to 14 mm high, unbranched.Hydrothecae tubular, roughly cylindrical at free part ( Fig. 22 ), diameter decreasing basally at adnate portion; minimum diameter at base. Hydrotheca strongly and regularly curved outwards ( Fig. 22 ), adnate in one-third of its adcauline length (adnate/free ratio 0.6). Adcauline wall convex; abcauline wall concave. Hydrothecal aperture circular, directed upwards, forming an angle of 30° with long axis of branch. Rim even, with few short renovations.

Large nematocysts relatively small and fusiform ( Fig. 30 ).

Coppinia not found.

REMARKS

See Peña Cantero et al. (2007) for an extensive discussion of this species, mentioning also the presence of a one-flap operculum in the hydrothecae. These authors characterized the species by the size and arrangement of the hydrothecae.Although there are other species of a similar size (e.g., A. infinita n. sp.) and with hydrothecae arranged in two planes making an obtuse angle (e.g., A. tortugasensis ), the combination of these characters with others such as the shape of the hydrothecae and the size of the nematocysts, makes this species easily identifiable.

Peña Cantero et al. (2007) included into this species the material assigned to Acryptolaria patagonica by Watson (2003) and Vervoort & Watson (2003) on morphological and dimensional grounds, since no information concerning the cnidome was provided by those authors. However, in the light of the diversity shown by the genus, we consider wiser to regard those records as doubtful, waiting for the study of the cnidome.

Concerning our present material, we have doubts about its conspecificity with Acryptolaria operculata . The material from BIOCAL 1 stn DW 70 is so scarce that it is not possible to compare branching pattern or hydrothecal arrangement. Moreover, it is practically deprived of coenosarc and only a single nematocyst could be found. It differs from the material studied so far in having much shorter hydrothecae with a relatively much longer free portion, though it agrees in the general shape of the hydrothecae and the size of the nematocyst. On the other hand, the material from CHALCAL 2 stn DW 76, a single c. 14 mm high stem, with hydrothecae arranged in two planes making an obtuse angle, agrees with previously studied material in the general shape of the hydrothecae and the size of the nematocysts, but differs in having much smaller hydrothecae and a flared hydrothecal rim.

Figures

FIG. 22. — Acryptolaria cf. operculata Stepanjants, 1979, hydrothecae: A, from BIOCAL 1 stn DW 70; B, C, from CHALCAL 2 stn DW 76. Scale bar: 250 μm.

FIG. 30. — Outline drawings of the large type nematocysts of Acryptolaria species discussed in the present report. Scale bar: 30 μm.