Sertularella recta Galea & Schories, 2017

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 : 297-299

Sertularella recta Galea & Schories , sp. nov.

Fig. 15 I-M; Table 21

Sertularella ? implexa . – Galea & Schories, 2012a: 40, pl. 3 fig. 4F-J [non Sertularella implexa ( Allman, 1888) ].

Sertularella polyzonias . – Allman, 1888: 55, pl. 26, figs 3, 3A. – El Beshbeeshy, 2011: 141, fig. 45 [non Sertularella polyzonias ( Linnaeus, 1758) ].

Holotype material: MHNG-INVE-79627; Chile, Región de Magallanes y de la Antártica Chilena, Punta Arenas, Faro San Isidro, -53.78174° -70.97391°, 40 m, coll. D. Schories, lot #11; 05.01.2011; colony composed of several fertile stems, up to 5.5 cm high.

Additional material: ZMH C11895; Argentine Shelf, no additional data; several branched and unbranched colony fragments, up to 1.5 cm high, one of which bears 3 female gonothecae. – ZMH C11888; FRV Walther Herwig, Stn. 327, -51.18333°, -56.95000°, 225 m; 29 Jun. 1966; two small, sterile colony fragments likely not belonging to the present species, although considered as conspecific by El Beshbeeshy (2011).

Diagnosis: Irregularly-pinnate colonies, with monosiphonic stems branched several times; internodes moderately long, slightly geniculate; hydrothecae flaskshaped, adnate for 1/3rd their length, swollen adaxially, abaxial cusps slightly produced, rim not thickened, internal cusps absent; gonothecae broadly ovoid, transversely wrinkled, aperture surrounded by 3-4 spines.

Etymology: From the Latin rectus, -a, -um (rego), meaning straight, with reference to the macroscopic appearance of both stems and branches.

Description: Hydrorhiza missing, but stems above origin from stolon comprising a monosiphonic, ahydrothecate basal part of varied length, with several proximal wrinkles; remainder of stems divided into moderately-long, slightly geniculate internodes by means of oblique constrictions of the perisarc slanting in alternate directions; nodes brownish in older parts of the colony, becoming transparent in younger ones. Branching pattern irregular, with side branches arising every 1-8 stem hydrothecae, immediately below their bases, through short, lateral apophyses; branching repeated several times, introducing a slight torsion in lower-order branches so as to accommodate the newly-formed ones, giving the colony a somewhat three-dimensional appearance, though it is rather compressed antero-posteriorly. Stems and branches of similar structure, except for the first internodes of the latter, which are comparatively longer than the subsequent ones, and provided with a couple of basal wrinkles. Hydrothecae placed distally on internodes, biseriate, alternate, adnate for about 1/3rd their adaxial length; free adaxial wall conspicuously swollen basally, decidedly convex, becoming concave towards aperture; abaxial wall straight or nearly so basally, becoming convex distally, where it forms a neck region, widening towards aperture; the latter tilted outwards and upwards, provided with 4 pointed, triangular cusps separated by deep, rounded embayments; no submarginal, intrathecal cusps. Gonothecae borne on stems and side branches, arising from below bases of hydrothecae; broadly ovoid, walls transversely wrinkled, wrinkles more obvious distally, becoming obsolete proximally; aperture surrounded by 3-4 pointed perisarc projections.

Dimensions: See Table 21.

Remarks: The material from the Falkland Is. assigned by Allman (1888) to S. polyzonias ( Linnaeus, 1758) shows striking resemblances to the present species, and is thought to be conspecific (N.B.: Allman’s specimen could not be examined, as it is apparently no longer extant in the collection of NHML; A. Cabrinovic, pers. comm.).

In addition, the reexamination of El Beshbeeshy’s (2011) sample ZMH C11895, assigned to the Linnean taxon, revealed that it belongs to the new species described herein. Among the material described by El Beshbeeshy, some colonies are reportedly said to reach as much as 19 cm high, their stems remaining always monosiphonic.

The typical shape of the colonies is illustrated in Galea & Schories (2012a, pl. 3F, as S.? implexa ), and a gonotheca in fig. 4J of the same paper.

Distribution: Chile – Región de Magallanes y de la Antártica Chilena [south of Peninsula Brunswick ( Galea & Schories, 2012a, as S.? implexa )]. Argentina – scattered records from the Patagonian Shelf, between 43°-53°S ( El Beshbeeshy, 2011, as S. polyzonias ). Falkland Is. ( Allman, 1888; El Beshbeeshy, 2011; both as S. polyzonias ).

Figures

Fig. 15. (A-E) Sertularella patagonica (d’Orbigny, 1842). Portion of fertile colony after Genzano (1990, as S. striata Stechow, 1923 b) (A), Blanco (1967, as S. atlantica Stechow, 1920) (B), Blanco (1974, as S. striata) (C, D), and Millard (1964, as S. striata) (E). (F, G) Sertularella pauciramosa Galea & Schories, 2014. Portion of colony from MHNG-INVE- 86235 (F) and hydrotheca from HRG- 0717 (G). (H) Sertularella quadrispinosa Watson, 2003, redrawn after original. (I-M) Sertularella recta Galea & Schories, sp. nov. Portions of colonies from MHNG-INVE- 79627 (I) and ZMH C 11895 (J). Hydrothecae from the same sources (K and L, respectively). Portion of fertile colony with gonotheca from MHNG-INVE- 79627 (M). N-R Sertularella robusta Coughtrey, 1876. Colony fragments from HRG- 0356 (N), Blanco [1963, as S. tenella (Alder, 1857)] (O) and NMSZ 1959.33. 499 (P). Hydrothecae from former and latter sources (Q and R, respectively). Scale bars: 200 μm (G, H, K, L, Q, R), 500 μm (M), 1 mm (A-F, I, J, N-P).