? Solenoscyphus decidualis Galea, 2015

Solenoscyphus decidualis Galea, 2015a: 9, figs 3B, 4C–D.

Material examined

PACIFIC OCEAN • a 5.7 cm high colony and the 1.1 cm long tip of a second colony, both without gonothecae; off New Caledonia, stn DW4715; 22°50′ S, 167°27′ E; 424 m; 18 Aug. 2016; KANACONO leg.; one cladium from the largest colony was used for DNA extraction, DNA1354; voucher MHNG-INVE- 120788; barcode identifier MK 073084; MNHN-IK-2015-375 • a colony without gonothecae, 6.8 cm high; off New Caledonia, stn CP4676; 22°51′ S, 167°30′ E, 383 m; 13 Aug. 2016; KANACONO leg.; a basal cladium was cut off and used for DNA extraction, DNA1355; voucher MHNG-INVE- 120789; barcode identifier MK 073085; MNHN-IK-2015-376 .

Remarks

The present material, forming pinnate colonies with lightly fascicled stems and long, tubular, weakly adnate hydrothecae, is in full agreement with the holotype described earlier by Galea (2015a). The perisarc of the colony (including that of the hydrothecae) is uniformly smooth, and the hydrothecal rim is thickened distally for only a very short distance (ca 40 µm) just below the aperture.

Despite forming regularly-pinnate colonies provided with tubular hydrothecae possessing rounded, deciduous opercula, the present species and S. candelabrum may prove to not be congeneric. The available 16S sequences place this species clearly outside the clades of Solenoscyphus and Staurothecidae (Fig. 20 and ‘Molecular study’ section), but without any supported relationships to other taxa. This makes it likely that this species does not belong to the genus Solenoscyphus . However, the available 16S data do not resolve sufficiently well the family relationships, and additional markers are needed for this purpose. Therefore, and also because no diagnostic traits are evident, we decided to leave it in the genus Solenoscyphus until a more detailed study allows firmer conclusions.

Distribution

Only known from off New Caledonia (Galea 2015a; present study).