Sertularella tenella ( Alder, 1856 )

Horia R. Galea, Dirk Schories, Verena Häussermann & Günter Försterra, 2017, Taxonomic revision of the genus Sertularella (Cnidaria: Hydrozoa) from southern South America and the subantarctic, with descriptions of five new species, Revue suisse de Zoologie 124 (2), pp. 255-321 : 304-306

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 ).

Figures

Fig. 17. (A-B) Sertularella subantarctica Galea, sp. nov. (continued), hydrothecae from SMNH 123839 (A), and female gonotheca from SMNH 123835 (B). (C-H) Sertularella tenella (Alder, 1857). Portions of stems from the Chilean materials HRG- 0359 (C) and HRG- 0361 (D), and comparison with the European specimen HRG- 1244 (E). Hydrothecae from the same sources (F, G and H, respectively). (I-L) Sertularella valdiviae Stechow, 1923 b (part). Portions of colonies from ZMH C 11886 (I), ANT XIX / 5 ID. 91 (J), and ZSM 20050522 (K). Hydrotheca from ZMH C 11886 (L). Scale bars: 200 μm (A, F-H, L), 500 μm (B), 1 mm (C-E, I-K).

Fig. 18. (A-D) Sertularella valdiviae Stechow, 1923 b (continued). Hydrothecae from ANT XIX / 5 ID. 91 (A), ZSM 20050522 (B) and ZSM 20050521 (C). Gonothecae from the latter source (D). (E) Sertularella vervoorti El Beshbeeshy, 2011, internode with hydrotheca. Scale bars: 200 μm (A-C, E), 500 μm (D).