Sertularella

Galea, Horia R. & Schories, Dirk, 2012, Some hydrozoans (Cnidaria) from Central Chile and the Strait of Magellan, Zootaxa 3296, pp. 19-67 : 45-46

Sertularella sp.

(fig. 5K–P, table 5)

Sertularella ellisi f. lagenoides — Leloup, 1974: 28, fig. 22. [not S. ellisii (Deshayes & Milne-Edwards, 1836) ]. Sertularella peregrina — Leloup, 1974: 31, fig. 25 (not S. peregrina Bale, 1926 ).

Material examined. Stn. RHO — 01.xi.2009, DS264 (15 m): several sterile stems, up to 1.4 cm high, on sponge substrate. Stn. TIB — 01.xi.2009, DS166 (15 m): numerous sterile stems, up to 1.4 cm high, epizoic on sponge (MHNG-INVE-79629); DS207 (17 m): a single, sterile stem, 0.9 cm high, on sponge. Stn. GNZ — 25.v.2007, S08 (10 m): several infertile stems, up to 1.4 cm high, on sponge. Stn. CHN — 25.iv.2011, S10 (2 m): six infertile stems, 4–7 mm high.

Description. Creeping, ramified, anastomosing stolon, giving rise to erect shoots up to 1.4 cm high; these unbranched or irregularly branched; divided into internodes of variable length by means of weak, oblique constrictions of perisarc; internodes collinear (fig.5L) or slightly zigzagging (fig. 5M). Each internode gradually widening from base to tip, bearing a hydrotheca distally. Side branches, when present, arising in front or rear side of stem, occasionally given off from within a stem hydrotheca (fig. 5N); structure similar to that of stem, though internode length may be comparatively short. Hydrothecae alternate, flask-shaped, slightly swollen basally, constricted below aperture; adcauline wall 2/5th adnate, free surface smooth or slightly wrinkled, abcauline wall slightly longer than free adcauline part; generally three internal perisarc cusps below the aperture: one abcauline and two latero-adcauline; hydrothecal margin with four triangular plates separated by rather shallow embayments. Gonothecae absent.

Remarks. In sample DS166 (Stn. TIB), this species co-occurs with Sertularella mixta sp. nov. (see above) on the same substrate, a sponge, and their size difference is striking, allowing rapid separation.

The pattern of branch formation in this species is peculiar for the genus: branches are given off not laterally, but in front or from rear side of the stem, perpendicular to it. The morphological variation within the available sample is illustrated in table 5. The development of intrathecal, submarginal cusps is variable, from absent, to slightly marked, to conspicuous, nearly reaching the center of hydrotheca. Hydrothecae in specimens from Stn. GNZ, S08 exhibit either 3 or 5 internal cusps (2 latero-adcauline, one abcauline, and, sometimes, 2 additional latero-abcauline), showing varied degrees of hypertrophy (fig. 5P).

Leloup's (1974) material assigned to both S. ellisi f. lagenoides and S. peregrina may belong to either this species or S. mixta , since no measurements allowing a reliable comparison were provided by this author. Sertularella ellisii is an essentially Mediterranean-eastern Atlantic species ( Ramil et al. 1992), while S. peregrina occurs in Australia ( Bale 1926); it is unlikely that their occurrence extends to the southwestern Pacific. Additionally, both S. ellisi and S. peregrina have more fusiform hydrothecae, thus different from the more tubular ones of the Chilean species.

Distribution in Chile. Recorded from Punta de Choros to Corral (present study).

World records. Impossible to evaluate based on current knowledge.