Sertularella

Sertularella ? lagena Allman, 1876

(fig. 4K, L)

Sertularella lagena Allman, 1876: 114. — Allman, 1879: 283, fig.

not Sertularella lagena — Stechow, 1925: 475, fig. 34 (=? S. antarctica Hartlaub, 1901).

Material examined. Stn. FSI — 04.i. 2011, S25 (40 m): three minute sterile stems, epizoic on Symplectoscyphus patagonicus sp. nov.

Description. Three monosiphonic, unbranched stems, ca. 3 mm high, with 3, 4, and 5 hydrothecae, respectively, arising from creeping hydrorhiza. Basal part, of varied length, with several wrinkles just above origin from stolon, then perisarc smooth; remainder of stem divided into internodes by means of twin, oblique constrictions of perisarc; internodes slender, 595–790 µm long, 130–155 µm wide at node; widening gradually towards distal end, where they bear a hydrotheca. Hydrothecae flask-shaped, distinctly swollen basally (maximum width 290–315 µm), narrowing distally to form a short neck region, then widening again at aperture; adnate for about 1/3rd of their adcauline length (205–265 µm); free adcauline wall 295–400 µm long, sigmoid, convex below, concave distally, perisarc smooth; abcauline wall 420–580 m long, concave below, though not as much as its free adcauline counterpart, then convex distally; aperture 210–270 µm wide, facing outwards and upwards, provided with 4 marginal cusps, the abcauline one most developed; cusps separated by moderately deep, semi-circular embayments; aperture composed of four triangular plates forming a pyramidal roof; internal projections of perisarc missing. Gonothecae absent.

Remarks. The small habit of the present specimens, along with the characteristic shape of their hydrothecae and the twin, basal constrictions of the perisarc delimiting the stem internodes, place them close to S. lagena Allman, 1876. However, the brief description, the limited illustrations and the lack of measurements in the account by Allman (1879) prevent us from determining whether they are conspecific or not, and examination of the type of S. lagena is required.

Stechow’s (1925) record of the species is suspect: the intrathecal perisarcal projections observed by him may, indeed, have been overlooked by Allman when he described S. lagena, but the characteristic position of the hydrothecae (the two rows being shifted unidirectionally so as to form an angle of ca. 90°), would certainly have not been overlooked. Additionally, the short branches springing alternately left and right from the stem resemble the characteristic habit of young colonies of S. antarctica Hartlaub, 1901 (see plate 3D).

Hartlaub (1901) placed, with a query, Allman's species in the synonymy of S. contorta Kirchenpauer, 1884, stating that a number of internodes observed by him in specimens originating from the Le Maire Strait, completely matched those originally illustrated for S. lagena. He also added that S. contorta was clearly distinguishable from S. picta (Meyen, 1834). However, from the account by Kirchenpauer, S. contorta appears similar to the type of S. gaudichaudi (Lamouroux, 1824) examined by Billard (1909, 1922), a species suspected by us to be a junior synonym of S. picta (Meyen, 1834) 8.

It becomes clear that, in order to solve these difficult taxonomic issues, a re-examination of the types of all the nominal species from the subantarctic is urgent and necessary.

Distribution in Chile. Strait of Magellan (present study).

World records. Kerguelen (Allman 1876, 1879).