Sertularella robusta Coughtrey, 1876

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 : 299

Sertularella robusta Coughtrey, 1876

Figs 12D , 15 N-R; Table 22

Sertularella robusta Coughtrey, 1876: 27 , pl. 3 fig. 6. – Leloup, 1960: 234, fig. 7. – Blanco, 1968: 215, pl. 4 figs 4-7. – p.p. Vervoort, 1972: 129, figs 40A, 41A. – Leloup, 1974: 33, fig. 27. – Blanco, 1976: 42, pl. 4 figs 1-3; 1994: 200. – Galea, 2007: 66, fig. 15E-I. – Galea et al., 2009: 2, 4. – p.p. El Beshbeeshy, 2011: 144, fig. 46A-D.

non Sertularella robusta . – p.p. Vervoort, 1972: 129, fig. 40B (= Sertularella microtheca Leloup, 1974 ). – p.p. El Beshbeeshy, 2011: 144, fig. 46E-H (= S. microtheca ). – Soto Àngel & Peña Cantero, 2015: 996, fig. 7G [= (?) Sertularella tenella ( Alder, 1856) ].

Sertularella tenella . – Jäderholm, 1905: 31, pl. 12 fig. 8. – Ritchie, 1907: 78. – p.p. Rees & Thursfield, 1965: 138. – Blanco, 1963: 173, figs 7-8 [non Sertularella tenella ( Alder, 1856) ].

Sertularella stepanyantae El Beshbeeshy, 2011: 20 [new name for Vervoort’s (1972, p. 129) record of S. robusta Coughtrey, 1876 ; nomen nudum].

Material examined: HRG-0626; Chile, Región de los Lagos, southern Chiloé, west of Punta Inio, -43.39300° -74.11769°, 26 m, coll. HSFS, HF6, lot A565; 22.02.2008; male colony composed of both stolonal and erect stems, up to 5 mm high, epizoic on Symplectoscyphus milneanus (d’Orbigny, 1842) . – HRG-0356; Chile, Región de Magallanes y de Antártica Chilena, Punta Arenas, Faro San Isidro, -53.78174° -70.97391°, 10 m, coll. D. Schories, lot PTA002; 25.02.2010; colony composed of numerous sterile stems, up to 15 mm high. – HRG-0797; Chile, Región de los Ríos, north of Corral, Chaihuin, -39.95730° -73.60245°, 6-12 m, coll. D. Schories; 06.03.2012; sterile stolonal colony epizoic on Halecium sp. – HRG- 0788; Chile, Región de Aysén, west of Canal Messier, -47.86020° -74.76023°, 5.3 m, coll. HSFS, HF13, lot C176; 16.03.2012; small colony composed of both stolonal hydrothecae and up to 4 mm high erect stems, bearing single male gonotheca. – HRG-1099; Chile, Región de los Lagos, Roca Gloria, -45.662433° -73.849266°, 20 m, coll. HSFS, HF21, lot #99; 05.04.2014; rich, fully fertile (male) colony composed mainly of stolonal hydrothecae and, occasionally, of short, erect stems (2-4 hydrothecate internodes), epizoic on Symplectoscyphus filiformis ( Allman, 1888) . – HRG- 1173; Chile, Región de los Lagos, southern Chiloé, Isla Yencouma, -43.4193° -74.0818°, 10 m, coll. HSFS, HF22, lot #65; 18.01.2015; a male colony composed of mostly stolonal hydrothecae, and a few, up to 3 mm high, erect stems. – NMSZ 1959.33.499; Burdwood Bank, -54.41667° -57.53333°, ca. 102 m, coll. Scottish National Antarctic ( Scotia ) Expedition 1902-1904; 01.12.1903; microslide ( Fig. 12D ) comprising 4 sterile stem fragments, 6-8 mm high, one of them branched once [material studied by Ritchie (1907, as S. tenella ), and listed by Rees & Thursfield (1965, p. 138)].

Description: Stolonal hydrothecae or short, erect, unbranched or sparingly-branched stems arising from creeping, branching, filiform hydrorhiza. A varied number of annuli at the stem bases, immediately above origin from stolon. Stems and side branches, when present, exclusively monosiphonic, divided into moderately-long, geniculate internodes by means of oblique nodes slanting in alternate directions. A hydrotheca, or a hydrotheca and a lateral apophysis immediately below its basis, confined to the distal end of each internode; basally, a twist. Branches arise irregularly (every 1-7 stem hydrothecae) and in the same plane as the stem; up to 2nd order branching observed; structure similar to stem, though 1 st internode comparatively longer than subsequent ones. Hydrothecae biseriate, alternate, coplanar; flask-shaped, swollen basally, adnate for 2/5th their adaxial length; surface provided by 4-6 transverse ridges; rim with 4 small, triangular, equally-developed cusps separated by deep, rounded embayments; 3 distinctive, plate-shaped, internal projections of perisarc below the hydrothecal aperture (2 latero-adaxial, 1 abaxial); operculum composed of 4 triangular flaps forming a pyramidal roof. Gonothecae arising from below the hydrothecal bases; broadly ovoid, surface with 6-7 transverse ribs, aperture apical, surrounded by 4 pointed cusps; external acrocysts in female.

Dimensions: See Table 22.

Remarks: The typical shape of a stolonal colony is illustrated in Galea (2007, fig. 15E), and of an erect stem in Galea (2007, fig. 15F). The gonothecae are illustrated in Galea (2007, fig. 15G, I).

Distribution: Chile – Región de los Ríos [north of Corral (present study)]; Región de los Lagos [around Isla Grande de Chiloé ( Leloup, 1974; Galea et al., 2009); Golfo de Ancud ( Leloup, 1974); Roca Gloria (present study)]; Región de Aysén [Guaitecas Archipelago ( Leloup, 1974; Galea, 2007); Canal Puyuhuapi ( Galea et al., 2009); Canal Messier (present study)]; Región de Magallanes y de la Antártica Chilena [Canals Castillo, Copihue, Pasaje, and Pitt Chico, as well as Angostura Inglesa and Isla Camello ( Galea, 2007); around Punta Arenas (present study); Magellan Strait (p.p. Vervoort, 1972)]. Patagonia – no localities given ( Leloup, 1960). Argentina – Provincia de Río Negro [Golfo de San Matías ( Blanco, 1994)]; Provincia de Santa Cruz [Puerto Deseado, Bahía Uruguay ( Blanco, 1963, as S. tenella )]; Provincia de Tierra del Fuego, Antártida e Islas del Atlántico Sur [Argentinean waters off the northern coast of Isla Nueva, Tierra del Fuego ( Blanco, 1968); off the eastern entrance of the Magellan Strait ( Blanco, 1976); south of Sloggett Bay, Beagle Canal ( Jäderholm, 1905, as S. tenella ; p.p. Vervoort, 1972); around Península Mitre (p.p. Vervoort, 1972)]; numerous scattered records from the Patagonian Shelf, between 40°-54° S (p.p. El Beshbeeshy, 2011). Between Tierra del Fuego and the Falkland Is. (p.p. Vervoort, 1972). Burdwood Bank ( Ritchie, 1907, as S. tenella ).

Figures

Fig. 12. (A) Sertularella (?) hermanosensis El Beshbeeshy, 2011. Likely a fragment of this species mounted on slide, as part of the type material of S. implexa (Allman, 1888). (B) Sertularella implexa (Allman, 1888), fragment from type colony mounted on slide. (C) Sertularella juanfernandezensis Galea, sp. nov., identified as S. polyzonias (Linnaeus, 1758) by Jäderholm (1910). (D) Sertularella robusta Coughtrey, 1876, identified as S. tenella (Alder, 1857) by Ritchie (1907). (E, F) Sertularella subantarctica Galea, sp. nov. Materials identified as S. allmani Hartlaub, 1901 by Jäderholm (1910, 1905) (E, F, respectively). (G, H) Sertularella valdiviae Stechov, 1923 a, two slides prepared from type colony.