Sertularella clausa ( Allman, 1888 )

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 : 266-268

Sertularella clausa ( Allman, 1888)

Figs 1D , 5 ; Table 4

Sertularia clausa Allman, 1888: 54 , pl. 25 figs 3, 3a. – Bedot, 1916: 219.

Sertularella clausa . – Nutting, 1904: 93, pl. 21 figs 3-4 (reexamination of the type). – Bedot, 1918: 236. – Milstein, 1976: 84, figs 24, 35.

non Sertularella clausa . – Fraser, 1938: 141, pl. 20 fig. 10; 1948: 241.

Sertularella argentinica El Beshbeeshy, 2011: 121 , fig. 38 (syn. nov.). – Soto Àngel & Peña Cantero, 2015: 993, fig. 7A-B.

non Sertularella argentinica . – Galea, 2007: 59, fig. 14A-C. – Galea et al., 2007c: 312, fig. 3I (= Sertularella robustissima Galea, Häussermann & Försterra , sp. nov.).

Sertularella gayi gayi . – Blanco, 1982: 157, figs 6-9 [non Ser- tularella gayi ( Lamouroux, 1821) ].

Material examined: NHML 1888.11.13.41; Uruguay, off Montevideo, ca. 1097 m; colony composed of ca. 15 sterile stems, up to 1.2 cm high, as well as a slide (now dried out, Fig. 1D ) containing a ca. 1.5 cm high, branched colony fragment, labeled “Challenger Stat. 320, Sertularia clausa , type, Monte Video, Depth 600 faths”. – ZMH C11882; FRV Walther Herwig, Argentine Shelf, no additional data; several colony fragments, up to 2 cm high, at least one gonotheca, identified as Sertularella argentinica El Beshbeeshy, 2011 . – ZMH C12145; FRV Walther Herwig 31, Stn. 676, Argentine Shelf, off Provincia del Chubut, -43.80500° -59.53333°, 570 m; 22.06.1976; fragmentary, fertile colony with monosiphonic stems, on axis of dead antipatharian [material studied by El Beshbeeshy (2011), as S. argentinica ].

Description: Large, up to ca. 17 cm high, bushy, irregularly and much branched colonies with either mono- or reportedly polysiphonic stems. Monosiphonic parts divided into short, almost collinear, rather thick internodes, by means of oblique constrictions of the perisarc slanting in alternate directions, not always clearly demarcated; distally, a hydrotheca to each internode. Side branches originating not laterally, but in either front or rear side of the stem, from below the hydrothecal bases; 1 st internode slightly longer than subsequent ones; remainder of branches with similar structure as the stem; tips of branches commonly forming anastomoses with neighboring counterparts, resulting in much tangled, three-dimensional structure. Hydrothecae short, tronconical, adnate for slightly more than half their length to the corresponding internode; abaxial wall nearly straight to imperceptibly concave for most of its length, becoming convex below aperture; free adaxial wall slightly convex to nearly straight, surface smooth to wavy; rim with 4 short, triangular cusps separated by shallow embayments; renovations occasional; a 4-flapped operculum. Gonothecae borne on side branches, arising from below the hydrothecal bases; male similar to female; long, slender, tubular to spindle-shaped, tapering abruptly above origin, slightly constricted apically; lateral walls undulated; aperture distal, large, surrounded by 4 triangular cusps, and provided with a 4-flapped operculum.

Dimensions: See Table 4.

Remarks: Upon the comparison of the holotype of S. clausa with the Argentinean material assigned by El Beshbeeshy (2011) to his supposedly undescribed species, S. argentinica , it appears that both are indistinguishable morphologically (compare Figs 5A, B and 5C, D , as well as their respective measurements in Table 4). The former is an obviously young, sterile colony, with monosiphonic, unbranched or sparinglybranched stems, not surpassing 1.2 cm in height. Their mode of branching, with side branches arising in either the front or rear side of the stems, is peculiar and distinctive. Additionally, the frequent occurrence of terminal stolonization characterizes this species [present study; Blanco (1982, as S. gayi gayi )].

Distribution: Uruguay – off Montevideo ( Allman, 1888). Argentina – scattered records from the Argentine Shelf, between 40°-53°S ( El Beshbeeshy, 2011, as S. argentinica ); Provincia de Tierra del Fuego, Antártida e Islas del Atlántico Sur [ca. 80 km off the northeastern coast of Isla de los Estados ( Blanco, 1982, as S. gayi gayi )]. Burdwood Bank – Soto Àngel & Peña Cantero (2015, as S. argentinica ). Falkland Is. – off the SE coast ( El Beshbeeshy, 2011, as S. argentinica ).

Figures

Fig. 1. (A, B) Sertularella allmani Hartlaub, 1901. Two holotype slides of Sertularia secunda Allman, 1888 (= Sertularia unilateralis Allman, 1888). (C) Sertularella blanconae El Beshbeeshy, 2011, material identified as S. gayi (Lamouroux, 1821) by Jäderholm (1903). (D) Sertularella clausa (Allman, 1888), holotype slide. (E, F) Sertularella contorta Kirchenpauer, 1884 identified as S. polyzonias (Linnaeus, 1758) by Jäderholm (1910) (E) and S. lagena Allman, 1876 by Stechow (1925) (F), respectively. (G) Slide material studied by Jäderholm (1905), containing S. contorta (colony on the left-hand side) and S. subantarctica Galea, sp. nov. (colony on right-hand side), the latter identified by him as S. allmani. (H-K) Sertularella gaudichaudi (Lamouroux, 1824). Slide materials identified as S. picta (Meyen, 1834) (H), S. antarctica Hartlaub, 1901 (I) and S. protecta Hartlaub, 1901 (J) by Jäderholm (1903); as S. protecta by Stechow, according to Rees & Thursfield (1965) (K).

Fig. 5. Sertularella clausa (Allman, 1888). Colony fragments from holotype (A, B), and specimens ZMH C 11882 (C) and C 12145 (D) assigned to S. argentinica El Beshbeeshy, 2011. Hydrothecae from holotype (E), ZMH C 11882 (F), ZMH C 12145 (G, H), Blanco (1982, as S. gayi gayi) (I). Scale bars: 200 μm (E-I), 1 mm (A-D).