Sertularella tenella

Sertularella tenella (Alder, 1856)

Sertularia tenella Alder, 1856: 357, pl. 13 figs 3-6. – Galea & Schories, 2012a: 45, fig. 5H-J.

non Sertularella tenella. – Jäderholm, 1905: 31, pl. 12 fig. 8. – Ritchie, 1907: 78. – p.p. Rees & Thursfield, 1965: 138. – Blanco, 1963: 173, figs 7-8 [all = Sertularella robusta Coughtrey, 1876].

Sertularella jorgensis. – Galea, 2007: 63, fig. 14G, H. – Galea et al., 2007b: 312, fig. 4B [non Sertularella jorgensis El Beshbeeshy, 2011 = Sertularella valdiviae Stechow, 1923b].

(?) Sertularella robusta. – Soto Àngel & Peña Cantero, 2015: 996, fig. 7G [non Sertularella robusta Coughtrey, 1876].

Material examined: MHNG-INVE-53215; Chile, Région de Magallanes y de la Antártica Chilena, Canal Farquhar, -48.48853° -74.20714°, 32 m, coll. HSFS, HF2, lot #45; 29.03.2005; a colony composed of both stolonal hydrothecae and erect stems up to 1.2 cm high, formerly identified as S. jorgensis (see Galea, 2007). – HRG-0361; Chile, Región de los Lagos, Caleta La Arena, Caleta Yerbas Buenas, -41.67263° -72.65650°, 20 m, coll. D. Schories, lot DS095; 08.03.2009; two sterile stems, 4 and 7 mm high. – HRG-0359; Chile, Región de los Lagos, Caleta La Arena, Caleta Yerbas Buenas, -41.67263° -72.65650°, 20 m, coll. D. Schories, lot S15; 26.04.2011; several sterile stems, 4-11 mm high, on worm tube. – HRG-1244; France, Brittany, N of Pointe Penmarc’h, off Gaouac’h rock, 23 m, coll. F-X. Decaris; 14.05.2016; a sterile colony, 2.5 cm high.

Description: Short (up to 1.2 cm high), erect, monosiphonic, unbranched stems or stolonal hydrothecae arising from creeping hydrorhiza; divided into relatively long, slender, geniculate internodes by means of oblique constrictions of the perisarc slanting in alternate directions; a hydrotheca distally to each internode. Hydrothecae biseriate, alternate, coplanar, tronconic, adnate for 1/3rd to their corresponding internodes; abcauline wall straight to slightly concave, with smooth to slightly wrinkled perisarc; free adcauline wall with 3-4 undulations, not always reaching abcauline side; rim somewhat everted, provided with 4 pointed triangular cusps separated by moderately-deep, semicircular embayments; closing apparatus composed of 4 opercular flaps with concentric striations; no internal, submarginal cusps. Gonothecae absent in all material from the study area.

Dimensions: See Table 25.

Remarks: The typical silhouette of a stem is shown in Galea (2007, fig. 14G). The hydrothecae in this material are less wrinkled than those of European specimens (compare Fig. 17F, G and H).

The material assigned earlier to S. jorgensis El Beshbeeshy, 2011 by Galea (2007) (now recognized as a junior synonym of S. valdiviae Stechow, 1923b, see below) differs from that nominal species mainly through the morphology of its hydrothecae (compare Fig. 17F, G and Fig. 18 A-C).

The rather thick internodes and the hydrothecae devoid of submarginal, intrathecal cusps in the material identified as S. robusta Coughtrey, 1876 by Soto Àngel & Peña Cantero (2015) equally point towards the present species.

Distribution: Chile – Región de los Lagos [Seno de Reloncaví (Galea & Schories, 2012a)]; Región de Magallanes y de la Antártica Chilena [Canal Farquhar (Galea, 2007; Galea et al., 2007b; both as S. jorgensis)]. Scotia Arc – Burdwood Bank, South Sandwich Is. (Soto Àngel & Peña Cantero, 2015, as S. robusta).