Scandia gigas Pieper 1884

Scandia gigas (Pieper, 1884)

(fig. 5A–C, table 8)

Lafoea gigas Pieper, 1884: 165.

Scandia gigas — Boero, 1981: 190, fig. 6.— Gili, 1986: 171, fig. 4.27B–C.— Altuna Prados, 1994: 158, pl. 23 figs A–E.— Peña Cantero & García Carrascosa, 2002: 59, fig. 11E–G.

Lafoea pocillum Hincks, 1868: 204, pl. 40 fig. 2.— Patriti, 1970: 27, fig. 27.

Campanularia (?) mutabilis — Broch, 1913: 10, fig. 13 [not Scandia mutabilis (Ritchie, 1907)].

Laomedea michael-sarsi Leloup, 1935: 22, fig. 9.

Scandia michael-sarsi — García Corrales et al., 1979: 20, fig. 9.

Scandia michaelsarsi — Boero et al., 1997: 31.

Hebella michael-sarsi — Vervoort, 1959: 242, fig. 16.

Hebellopsis michaelsarsi — Calder et al., 2003: 1188, fig. 10.

Material examined. Stn. 2: 22.01.2008 —a few hydrothecae, but no gonothecae, on algae. Stn. 7: 25.03.2008 —two hydrothecae, but no gonothecae, on gree alga; 27.03.2008 —a colony with male gonothecae, on Dictyota sp. and calcareous alga.

Type locality. Eastern coast of the Adriatic Sea.

Description. Colonies exclusively stolonal, with individual hydrothecae and gonothecae arising from creeping stolon. Hydrothecal pedicels of variable length, perisarc undulated to spirally grooved. Hydrothecae tubular, elongated, walls nearly parallel, perisarc smooth; narrowing towards base and merging imperceptibly into pedicel; margin distinctly everted, aperture circular, rim even; a thick diaphragm basally. Hydranths with 16–20 filiform tentacles. Male gonothecae elongated-ovoid, borne on short, undulated pedicel; gonophore, fixed sporosac, containing a homogenous mass of tissue around blastostyle; large nematocysts present in tissues. Female gonothecae not seen. Nematocysts (undischarged): small capsules (6.8–7.4) × (1.8–2.1) µm; medium-sized capsules (8.4–9.1) × (2.6–3.1) µm; large capsules (18.6–20.3) × (6.3–6.8) µm.

Remarks. The trophosome of Scandia michaelsarsi (Leloup, 1935) appears morphologically indistinguishable from that of S. gigas, based on descriptions and illustrations from the literature (Leloup 1935, Vervoort 1959, García Corrales et al. 1979, Calder et al. 2003). However, all of the records attributable to Leloup’s (1935) species were based on sterile material, and therefore no comparison could be made with the gonosome of S. gigas. The above-cited authors did not make any connection between the two species and considered S. michaelsarsi as valid, while others (Altuna Prados 1994, Peña Cantero & García Carrascosa 2002) included at least the eastern Atlantic records of S. michaelsarsi in the synonymy of Pieper’s (1884) species. However, Leloup (1935) considered the material described by Broch (1913) as Campanularia (?) mutabilis Ritchie, 1907 from Cape Bojador (eastern Atlantic) as being conspecific with his new Laomedea michaelsarsi from the Dry Tortugas (western Atlantic), suggesting the occurrence of his species on both sides of the Atlantic.

Moreover, Boero et al. (1997) examined the syntype material of Leloup’s species and found it similar with S. gigas, especially in the presence of a true diaphragm at the hydrothecal base. In addition to the close morphological similarities illustrated in various accounts from the literature, a comparison of measurements for several representative records of both S. gigas and S. michaelsarsi was established (table 8). It appears that only little variation in size could be noticed, which proves that they are undoubtedly conspecific.

The present, fertile material from the Lesser Antilles is solid evidence of the occurrence of S. gigas in the western Atlantic, although its presence was previously questionable (see Peña Cantero & García Carrascosa 2002). However, some if not all of Fraser’s (1944) records of Hebella (?) pocillum (Hincks, 1868) from boreal waters are more likely based on hydroids of Lafoea dumosa (Fleming, 1828), according to Cairns et al. (2002).

TABLE 8. Measurements of Scandia gigas (Pieper, 1884), in µm.(1)Microslide preparation, Mediterranean material from La Ciotat, France. (2)Approximate dimensions calculated from fig. 6A & C. (3)Approximate dimensions calculated from fig. 11E & G.

Scandia gigas (Pieper, 1884) Scandia michaelsarsi (Leloup, 1935) Distribution. Mainly known from the Mediterranean, but also reported from both the Lusitanian and Mauritanian Atlantic provinces (Peña Cantero & García Carrascosa 2002). Occurs additionally in the tropical western Atlantic (Leloup 1935, present study), and the Galapagos (Calder et al. 2003).