Silicularia

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 : 8-10

Silicularia ? bilabiata ( Coughtrey, 1875)

( Fig. 1 K, L, Table 2 )

Campanularia bilabiata Coughtrey, 1875: 291 , pl. 20 Figs 46–49.

Silicularia rosea ― Galea et al., 2009: 18 , Fig. 4 G–M (not S. rosea Meyen, 1834 ).

Material examined. Corral, Chaihuin/Huiro, lat. -39.95000, long. -73.61667, 30.xi.2011, 8‒ 10 m, sample 58: small colony with immature, most probably female gonothecae. HF6, “Inio 5”, lat. -43.40000, long. -74.08333, 24.ii.2008, 8 m, sample A504: colony with incompletely formed female gonothecae, on seaweed (MHNG-INVE- 62833).

Remarks. A small colony (sample 58) with immature (likely female) gonothecae occurs in the present collection and corresponds in every respect to the material assigned earlier ( Galea et al. 2009, MHNG-INVE- 62833) to S. rosea Meyen, 1834 . Both specimens exhibit laterally flattened hydrothecae with equally developed walls, and their gonothecae are comparatively wider with respect to those in the material described below, that we are now assigning to Meyen’s species. In spite of the opinion expressed by Vervoort & Watson (2003, p. 444), stating that “there are no reliable characters that separate Silicularia rosea Meyen, 1834 from Campanularia bilabiata Coughtrey, 1875 ”, the peculiar position of the hydrothecal rim (compare Fig. 1 K with 1M) and the comparatively broader gonothecae (compare Fig. 1 L to 1N; see Table 2 ) set the present material apart from the typical concept of S. rosea , as illustrated through the redescription of the type by Hartlaub (1905, p. 573, Fig. T1).

However, owing to the scarcity of specimens in hand, it is impossible to ascertain the degree of morphological variation of the hydrotheca, especially regarding the position of its aperture. Though all specimens inspected had the plane of the aperture perpendicular to the long axis of the theca, thus resembling to the original illustration provided by Coughtrey (1875, Pl. 20 Fig. 46), it was already shown ( Hilgendorf 1898, Bale 1924) that it may be inclined to one side, exactly as in S. rosea . Since the present identification is provisional and not intended to clarify the taxonomy of this nominal species at this stage, it should be taken with care, pending the re-examination of the syntype of Campanularia bilabiata designated by Ralph (1956, p. 287).

The relationships between S. bilabiata and both Eucopella campanularia von Lendenfeld, 1883 and E. reticulata Hartlaub, 1905 , all provided with broad, ovate, laterally flattened gonothecae, are unclear at present. Distribution in Chile. South of Chiloé ( Galea et al. 2009), and Corral (present study).

World records. The lack of knowledge on the specific limitation of S. bilabiata prevents us from establishing an exhaustive list of distributional records.

Figures

FIGURE 1. A, B: Hebella cf. scandens (Bale, 1888) — hydrotheca (A); gonotheca (B). C ‒ D: Hebella striata Allman, 1888 — hydrotheca (C); gonotheca (D). E, G, H: Phialella? falklandica Browne, 1902 — portion of erect stem (E) compared with that of P. quadrata (Forbes, 1848) (F); gonotheca seen laterally (G) and apically (H), compared with those of P. quadrata (I, stolonal; J, borne of stem). K, L: Silicularia? bilabiata (Coughtrey, 1876) — two hydrothecae (K); female gonotheca (L). M ‒ O: Silicularia rosea Meyen, 1834 — two hydrothecae (M) compared with specimens from Tristan da Cunha assigned to S. hemisphaerica (Allman, 1888) (P); female (N) and male (O) gonothecae, compared to homologous gonothecae (Q and R, respectively) from Tristan. S: Halecium corrugatissimum Trebilcock, 1828 — small stem with female gonotheca. Scale bars: 300 µm (A, B, E, F, S), 500 µm (C, D, G ‒ J), and 1 mm (K ‒ R).

FIGURE 4. A ‒ F, M: Cnidomes of some Halecium species discussed herein— H. flexile Allman, 1888 (A); H. balei (B); H. humeriformis sp. nov. (C); H. maximum sp. nov. (D); H. tristaniensis sp. nov. (E); H. modestum sp. nov. (F). G: Halecium pallens Jäderholm, 1904 — female gonotheca. H ‒ M: Halecium tehuelchum (d’Orbigny, 1842) — fragments of colonies (H), primary hydrophore and renovated hydrotheca (I); female gonotheca (J) and shape variation (K); male gonothecae (L); cnidome (M). Scale bars: 10 µm (A ‒ F, M); 300 µm (I, J, L), 500 µm (G, K), 1 mm (H).

Tables

TABLE 2. Comparison of species of Silicularia Meyen, 1834; dimensions are given in µm.

	S. bilabiata (Coughtrey, 1875)	S. rosea Meyen, 1834	S. hemisphaerica (Allman, 1888)
Reference	Present study, as S. bilabiata	Present study, as S. Blanco (1967b), as rosea S. bilabiata	Galea (2010b), as S. Markannerrosea; present study Turneretscher (1890), as H.atlantica
Pedicel
- length	725–4335	≤ 8000 331–8000	≤ 5500 1000–5000
- diameter	170–240	150–270 147–276	100–175 180
Hydrotheca
- length lowered wall	635–970	535–680 736–993	330–450 350
- length raised wall	635–970	720–900 828–1159	540–640 660
- height basal chamber	135–365	280–415 –	215–265 –
- diameter at aperture	500–700	770–925 699–828	480–550 300–630
♀ Gonotheca
- length	1560–1845	≤ 4000 3128–3827	≤ 2500 2700
- max. width	1105–1170	730–855 644–883	575–685 670
- diameter at aperture	–	645–805 552–828	295–425 –
♂ Gonotheca
- length	–	≤ 5000 2024–4340	≤ 2000 1700
- max. width	–	550–695 239–570	250–305 250