Symplectoscyphus paraglacialis El Beshbeeshy 2011

Symplectoscyphus paraglacialis El Beshbeeshy, 2011

(fig. 6K–N, table 8)

Symplectoscyphus paraglacialis El Beshbeeshy, 1991: 220, fig. 55 (nomen nudum). — El Beshbeeshy, 2011: 169, fig. 55.? Symplectoscyphus glacialis — Vervoort, 1972: 171, figs 56, 57B, C.

Material examined. Stn. FSI — 04.i.2011, S29 (40 m): several sterile stems, up to 3.5 cm high, epizoic on basal part of a stem of an unidentifiable hydroid, itself heavily overgrown by bryozoan (MHNG-INVE-79640); S33 (30 m): a single, sterile fragment, 1.9 cm high.

Symplectoscyphus paraglacialis El Beshbeeshy, 2011 Symplectoscyphus

glacialis

(Jäderholm, 1904) References Present study Vervoort (1972), as S. El Beshbeeshy Peña Cantero et al.

glacialis (2011) (2002), syntype

Internodes

– length 590–800 475–610 696–928 500–730 Description. Colonies attached to an unidentifiable hydroid substrate (the latter overgrown by bryozoan), their basal part could not be examined. Colonies irregularly ramified, stems and branches (up to 2nd order) monosiphonic, divided into internodes by more or less distinct constrictions of the perisarc; the latter rather thin and transparent. Internodes rather long, about two times as long as the adnate part of the hydrothecal wall, each bearing distally a hydrotheca, these alternate. Side branches originating immediately below the hydrothecal bases, either in front or the rear side of the colony, giving it a three dimensional appearance; basal internode of each side branch comparatively longer than the following ones. Hydrothecae tubular, curved outwards and facing slightly upwards; abcauline side rather straight basally, gently curving downwards in distal one third; adaxial side less than half adnate, free wall slightly sigmoid, adnate wall straight to slightly curved. Aperture with three pointed cusps separated by deep embayments, margin often renovated several times, though renovations obscured by each other. Lateral walls of hydrotheca with line of desmocytes running from junction between base of hydrotheca and lower part of adnate adaxial wall, to about one third of abcauline wall; occasionally a foramen just underneath the hydrothecal base. Gonothecae absent.

Remarks. El Beshbeeshy (2011), after comparing the syntype of Symplectoscyphus glacialis (Jäderholm, 1904) to his southwestern Atlantic specimens, concluded that the latter belonged to a different and new species, S. paraglacialis. Several distinctive features were listed by him, as follows: 1) shorter and slender internodes in S. glacialis; 2) absence of hydrothecal renovations in S. paraglacialis; 3) a much larger hydrothecal rim in S. paraglacialis; 4) hydrothecae about half adnate in S. glacialis, and with a much longer free adaxial wall in S. paraglacialis; 5) hydrothecal cusps more blunt in S. glacialis.

Some of these features seem more reliable taxonomically that others, e.g. the size of the hydrothecae (see table 8), its curvature, the relative length of the free and adnate parts of its adaxial wall, as well as the shape of the marginal cusps [compare our figure 6L–N to figure 6 in Peña Cantero et al. (2002)]. Based on these features, El Beshbeeshy (2011) included the material assigned by Vervoort (1972) to S. glacialis in the synonymy of his species, but some opinions diverge, as exemplified by Peña Cantero et al. (2002).

Both species share two common features: 1) the sides branches are given off in front of the stems, not laterally, giving the colonies a three dimensional appearance; 2) the relative position of the two rows of hydrothecae which, in some parts of the colonies, may form an obtuse angle. The latter was not obvious in our rather scarce material.

The finding of fertile specimens attributable to S. paraglacialis will improve our knowledge on this insufficiently-known species, and will clarify its relationships to S. glacialis.

Distribution in Chile. The present material originates from the Strait of Magellan and represents the first record of this species from Chile.

World records. Off the Argentinean provinces of Buenos Aires and Rio Negro (El Beshbeeshy 2011),? Ross Sea (Vervoort 1972).