Ectopleura dumortieri ( van Beneden, 1844 )

Galea, Horia R., 2007, Hydroids and hydromedusae (Cnidaria: Hydrozoa) from the fjords region of southern Chile, Zootaxa 1597 (1), pp. 1-116 : 31-33

Ectopleura dumortieri ( van Beneden, 1844)

(fig. 8A–C, pl. 2A)

Tubularia dumortieri van Beneden, 1844: 50 , pl. 2.

Ectopleura dumortieri (i): Hincks, 1868: 124, pl. 21 fig. 4; Mayer, 1910: 69, pl. 5 figs 4–5, pl. 6 figs 1, 1’, 2; Stechow, 1923: 50; Hargitt, 1924: 472, pl. 1 figs 3–4; Fraser, 1944: 92, pl. 15 fig. 65; Russell, 1953: 76, figs 33A–C, pl. 3 figs 5–6; Kramp, 1959: 88, fig. 37; 1961: 34; 1968: 13, fig. 23; Brinckmann-Voss, 1970: 22, figs 22–25, pl. 2 fig. 1; Russell, 1970: 233; Calder, 1971: 23, pls 1B, 6B; Fagetti, 1973: 36, pl. 1 fig. C; Hirohito, 1988 (English text): 16, fig. 3A–B; Goy et al., 1991: 103, fig. 7; Migotto, 1996: 24; Bouillon et al., 2004: 105, fig. 55G–J.

Material examined. Stn. COM 04 —28.i.2006, 19– 23 m, S166: one colony composed of numerous stems, up to 6 cm high, on wood ( MHNG INVE 53491). Stn. COM 06 —26.i.2006, 28– 30 m, S156: one colony with ca 12 hydranths, some with medusa buds, stems up to 6 cm high, on polychaete tube ( MHNG INVE 53481). Stn. COM 10 —25.xii. 2004, 10 m, S66: one colony with numerous stems 2–3 cm high, most of the hydranths shed, with medusa buds, on dock chain. Stn. COM 14 —26.ii.2005, 10– 15 m, S25: several stems, about 3 cm high, hydranths with immature medusa buds, on polychaete tube, 2 slides ( MHNG INVE 53180). Stn. IVM — 28.iii. 2005, 25 m, S32: several sterile stems about 1 cm high ( MHNG INVE 53193). Stn. CFQ — 29.iii. 2005, 32 m, S73: one stem, hydranth relatively badly preserved and probably without gonophores, on gorgonian. Stn. SWA — 15.iii. 2006, 30 m, S135: one colony with ca 12 stems, up to 3.5 cm high, some hydranths shed, with mature medusa buds ( MHNG INVE 53416). Plankton —off the Huinay Scientific Field Station, 07, 11, 12, 13, 18, 19.ii.2006, 50–0 m, several medusae ( MHNG INVE 49039).

Type locality. Ostende , Belgium .

Remarks. This well-known species needs no additional redescription. A recent description of the hydroid stage is found in Bouillon et al. (2004). The structural details and the developmental stages of the medusa were studied by Russell (1953).

The hydranths in the present material have 21–28 tentacles in both the aboral and oral rows. The number of blastostyles is, however, remarkable: up to 20 such structures were seen in some hydranths. The medusae caught from the plankton were up to 1.9 mm in height and 2.0 mm in width. Cnidome (polyp stage):

a) microbasic mastigophores, undischarged (10.4–11.4) x (3.5–4.0) µm, discharged (9.6–9.9) x 3.5 µm;

b) large stenoteles, undischarged (10.4–11.9) x (9.9–10.9) µm, discharged (9.4–10.4) x (7.9–8.9) µm;

c) small stenoteles, undischarged (6.9–8.4) x (5.9–6.4) µm, discharged (5.4–5.9) x (3.5–4.0) µm;

d) desmonemes, undischarged (4.9–5.4) x (3.2–3.5) µm;

e) anisorhizas, discharged (7.9–8.4) x (7.4–7.7) µm.

Cnidome (medusa stage):

a) stenoteles, on tentacles and the longitudinal nematocyst rows, undischarged (8.5–8.8) x (7.4–7.7) µm, discharged (5.8–6.4) x (5.6–5.9) µm;

b) microbasic mastigophores, on the longitudinal nematocyst rows, undischarged (9.0–10.1) x (3.7–4.2) µm, discharged (8.5–9.0) x (3.2–3.4) µm;

c) anisorhizas, on the longitudinal nematocyst rows, undischarged ca 8.5 x 8.0 µm, discharged (8.0–8.5) x (7.4–8.5) µm;

d) desmonemes, on tentacles, undischarged (5.8–6.4) x (3.7–4.0) µm.

World distribution. The polyp stage was recorded from eastern and western Atlantic, Mediterranean and Japan ( Migotto 1996). The medusa stage is found along the European coasts, including Mediterranean, west coast of Africa, North America (from South Carolina to Cape Cod), Brazil, India, Pacific coast of Mexico ( Kramp 1959), China and Vietnam ( Kramp 1968). This species has probably a worldwide distribution.

Records from Chile. The polyp stage was found along nearly the entire study area, between 42°S and 48°S. Medusae were collected from fjord Comau. Additional records of the medusa stage are those of Fagetti (1973), from Valparaíso Bay, and Palma et al. (2007) who extended southwards its known distribution to the southern channels (from the Gulf of Corcovado to Pulluche-Chacabuco channels).