Sertularella subantarctica Horia R. Galea & Dirk Schories & Verena Häussermann & Günter Försterra 2017, sp. nov.

Sertularella subantarctica Galea, sp. nov.

Figs 1G, 12E, F, 16 H-Q, 17 A-B; Table 24

Sertularella protecta p.p. Hartlaub, 1901: 79.

Sertularia (Sertularella) polyzonias. – Pfeffer, 1889: 54 [non Sertularella polyzonias (Linnaeus, 1758)].

Sertularella Allmani. – Jäderholm, 1905: 32, pl. 12 fig. 11; 1910: 5 [non Sertularella allmani Hartlaub, 1901].

Sertularella antarctica. – Jäderholm, 1905: 32, pl. 13 fig. 1 [non Sertularella antarctica Hartlaub, 1901)].

Sertularella sp. – El Beshbeeshy, 2011: 121, fig. 37E.

(?) Sertularella picta. – p.p. Millard, 1971: 405, fig. 6B [non S. picta (Meyen, 1834)].

non Sertularella picta. – Millard, 1971: 405, fig. 6A [= (?) Ser- tularella gaudichaudi (Lamouroux, 1824)].

Holotype material: SMNH 123839; South Georgia, Cumberland Bay, coll. Swedish South Polar Expedition 1901-1903; 09.05.1902; microslide (Fig. 12F) comprising three sterile colony fragments, 2.6, 3.0 and 3.5 cm high [material incorrectly assigned to S. antarctica Hartlaub, 1901 by Jäderholm (1905); illustrated by him in his pl. 13 fig. 1, re-illustrated herein in Fig. 17A; note that the identification written down on the label of the slide is “ Sertularella Allmani Hartl ”].

Paratype material: ZMH C04206; South Georgia, German International Polar Year Expedition 1882-1883, coll. K. von den Steinen; (day and month unavailable) 1883; a colony composed of numerous sterile stems, up to 3.2 cm high, on stem of tubulariid hydroid and unidentified substrate, labeled S. protecta Hartlaub, 1901, and suspected by El Beshbeeshy (2011) to belong to an undescribed species.

Additional material: SMNH 123851; Falkland Is., Port William, coll. Swedish South Polar Expedition 1901-1903, Stn. 39, 40 m; 04.07.1902; microslide (Fig. 1G) containing 2 species: 1) on the right-hand side, two sterile colony fragments, 1.3 and 1.5 cm high, assignable to S. subantarctica Galea sp. nov., but identified by Jäderholm (1905) as S. allmani Hartlaub, 1901, and illustrated by him in his pl. 12 fig. 11, re-illustrated herein in Fig. 16K, P; 2) on the left-hand side, a ca. 2 cm high, fertile colony of S. contorta Kirchenpauer, 1884, illustrated by Jäderholm (1905, pl. 12 figs 9-10), and re-illustrated herein in Fig. 6C, I. – SMNH 123835; Falkland Is., Port William, 12 m, Swedish Magellanic Expedition 1907-1909, coll. C. Skottsberg; 07.11.1907; microslide (Fig. 12E) containing 3 colony fragments, 0.5-1.5 cm, the largest bearing two female gonothecae [material assigned by Jäderholm (1910) to S. allmani Hartlaub, 1901]. – ZMH C04384; South Georgia, German International Polar Year Expedition 1882-1883, coll. K. von den Steinen; (day and month unavailable) 1883; two sterile fragments 1.7 and 3.8 cm high (most probably branches) on seaweed, labeled S. protecta Hartlaub, 1901 (it cannot be excluded that this material is part of ZMH C04206). – ZMH C04211; South Georgia, German International Polar Year Expedition 1882-1883, coll. A. Zschau, no additional data; likely 1883; about 3 short (up to 7 mm high), sterile stems (material labeled S. protecta Hartlaub, 1901).

Diagnosis: Stems monosiphonic, densely and pinnately branched; internodes uniformly short and thick; both hydrothecae and side branches shifted on to one side of the stem at a very acute angle, not exceeding 90°; hydrothecae big, though short (with respect to their width) and swollen adaxially, abaxial cusp produced, rim thickened, 3 internal, submarginal projections of perisarc, not always present.

Etymology: Named after its area of distribution.

Description: Undamaged colonies most probably exceeding 4 cm high; arising from tortuous, creeping, branching stolon; stems monosiphonic in all material inspected, with 1-5 basal twists; densely and pinnately branched; both stems and branches divided into uniformly short, thick internodes, by means of deep, oblique nodes slanting in alternate directions; a hydrotheca, or a hydrotheca and a short apophysis immediately below its base, confined to the distal end of each internode; a bulge at each end of the internodes; both hydrothecae and apophyses conspicuously shifted on to one side of the colony, giving it an anterior and a posterior side; angle between the two rows of branches acute, not exceeding 90°. Branching pattern (Fig. 16L) distinctive: branches occur in “pairs” composed of two successive internodes bearing lateral apophyses in opposite directions; each pair of branches is separated from the next one through one (upper part of the stem) or two (lower part of the stem) hydrothecate internodes devoid of apophyses. Branches with similar structure as the stems, except for the 1 st internode that is imperceptibly longer than subsequent ones, and provided basally with a couple of distinct twists. Hydrothecae large, flask-shaped, adnate for about 2/5th their adaxial side to the corresponding internode, conspicuously swollen adaxially; abaxial wall slightly concave in middle, to nearly straight throughout; free adaxial wall distinctly sigmoid: convex for most of its length, becoming suddenly concave below aperture; the latter quadrate, surrounded by 4 prominent, triangular cusps; abaxial one conspicuously produced, adaxial one the shortest, lateral ones unequally developed (“anterior” one shorter than “posterior” one); rim thickened, without renovations; 3 internal, submarginal projections of the perisarc (2 latero-adaxial, 1 abaxial), inconstantly present; a 4-flapped operculum. Perisarc thick throughout the colony. Gonothecae borne on side branches, given off from below the base of a hydrotheca; urn-shaped, transversely wrinkled, tapering below, distally provided with a short, neck region, bearing apically the aperture surrounded by 4 short, though strong spines.

Dimensions: See Table 24.

Remarks: The internal, submarginal cusps are variably present either among the hydrothecae of various stems, or among those of the same stem. For example, in sample SMNH 123839, the abaxial cusp is nearly always present, while the 2 latero-adaxial occur less frequently; conversely, in sample SMNH 123851, the cusps seem to be constantly absent.

Distribution: South Georgia – Pfeffer (1889, as S. polyzonias); p.p. Hartlaub (1901, as S. protecta); Jäderholm (1905, as S. antarctica in text, and S. allmani on the label of slide material); El Beshbeeshy (2011, as S. sp. nov.). Falkland Is. – Port William (Jäderholm, 1905, p.p. 1910, both as S. allmani). (?) South African Subantarctic Islands – Marion I. (Millard, 1971, as S. picta).