Sertularella pauciramosa Galea & Schories

Galea, Horia R., Schories, Dirk, Försterra, Günter & Häussermann, Verena, 2014, New species and new records of hydroids (Cnidaria: Hydrozoa) from Chile, Zootaxa 3852 (1), pp. 1-50 : 35-36

Sertularella pauciramosa Galea & Schories , sp. nov.

(Plate 3B; Fig. 6F, H; 7D; Table 8 )

Material examined. Taltal, Punta Morada, lat. -25.36667, long. -70.45000, 20.iv.2012, 15 m, sample 13: up to 4 cm high, female colony on worm tube (paratype: MHNG-INVE-86234). Taltal, lat. -25.38333, long. -70.46667, 21.iv.2012, 20 m, sample 07: up to 3.5 cm high, sterile colony on algae (paratype: MHNG-INVE-86233); 23.iv.2012, 22 m, sample 17: up to 6 cm high, male colony on worm tube (holotype: MHNG-INVE-86235).

Description. Colonies arising from creeping, branching, anastomosing hydrorhiza. Stems erect, monosiphonic, slightly geniculate to almost straight (Pl. 3B), perisarc rather thick, almost transparent; a varied number of basal annuli above origin from stolon, followed by a short, smooth part; remainder of cauli divided into internodes by oblique constrictions of the perisarc, slightly marked to indistinct, slanting in opposite directions. Each internode rather short, carrying a latero-distal hydrotheca; adaxial cusp of one hydrotheca almost reaching the base of following one. Side branches, when present, arising irregularly from below bases of stem hydrothecae, generally laterally (giving the colony a coplanar appearance) or, more rarely, slightly in front or rear side of the colony (Fig. 6F). Base of branch delimited from stem by a rather distinct node; first internode generally longer than subsequent ones. Hydrothecae (Fig. 6H) alternate, flask shaped, slightly curving outwards; adnate for 2/5th their adaxial length; free adaxial wall smooth to wavy (in which case provided with 2–3 weak undulations); abcauline wall varied in shape, from slightly concave, to straight, to rarely convex; aperture perpendicular to long axis of hydrotheca, constricted below rim; four pointed triangular cusps separated by shallow embayments; operculum of four triangular plates. Gonothecae of both sexes given off from below the bases of stem hydrothecae; ovoid, walls undulated to occasionally rather smooth; male longer and slightly slender than female (compare Fig. 7D1 and 7D2); aperture mounted on short neck provided with 3–4 distal horns flanking the aperture; female containing up to 20 large oocytes.

Remarks. The general appearance, the mode of branching, the shape of both hydro- and gonothecae recall the widely-spread S. polyzonias (Linnaeus, 1785) . A comparison with specimens of the latter from Brittany, France (Fig. 6G), showed −however − that S. pauciramosa is a smaller species, with less adnate hydrothecae [about 2/5th, compared to 1/2 or less in S. polyzonias , this feature being also evident from the accounts of Ramil & Vervoort (1992) and Ramil et al. (1992)].

Etymology. The specific name results from the fusion of two Latin words, pauci (meaning few) and ramus (meaning branch), and illustrates the rather scarce branching pattern of the colonies.

Distribution in Chile. Only known from around Taltal (present study).

Sertularella pauciramosa sp. nov. S. polyzonias (Linnaeus, 1758)

Reference Present study Present study Ramil et al. (1992) Internodes

Material examined. Corral, Chaihuin/Huiro, lat. -39.95000, long. -73.61667, 17.x.2011, 18 m, sample 01: fertile colony on sponge, stems up 3.5 cm high (MHNG-INVE-86241); 22.iii.2012, 6 m, sample 13: fertile colony on sponge, stems up to 3.0 cm high (MHNG-INVE-86242).

Remarks. Besides its discovery in Chile by Hartlaub (1901b), the second record from the country ( Galea & Schories 2012a) was based on sterile specimens. The present material, with gonothecae, is in agreement with earlier descriptions [ Blanco (1967a), as S. glacialis ( Jäderholm, 1904) ; Blanco (1976), as S. modestus (Hartlaub, 1901) ; Blanco (1980)], and confirms our previous identification.

Distribution in Chile. Calbuco (Hartlaub 1901), Punta de Choros ( Galea & Schories 2012a), and Corral (present record).

World records. Argentina (see Galea & Schories 2012a).

Tables

TABLE 8. Comparison of Sertularella pauciramosa sp. nov. with S. polyzonias (Linnaeus, 1758); measurements in µm.

- length 815–1140	890–1170	816–912
- diameter at node 195–230	230–310	260–302
Hydrotheca
- free adaxial wall 390–425	445–535	330–375
- adnate adaxial wall 315–380	405–435	475–490
- abaxial wall 635–690	670–730	576–605
- maximum width 335–365	400–425	–
- diameter at aperture 220–275	275–290	303–345
Gonotheca
- length 1710–1965 (♂) 1490–1710 (♀)	Not seen	1770–1950
- width 660–730 (♂) 660–805 (♀)	Not seen	740–850
Symplectoscyphus flexilis (Hartlaub, 1901) (Fig. 7E, F)