Eudendrium moulouyensis Marques, Pena Cantero and Vervoort, 2000

Gravili, Cinzia, Vito, Doris De, Camillo, Cristina Gioia Di, Martell, Luis, Piraino, Stefano & Boero, Ferdinando, 2015, The non-Siphonophoran Hydrozoa (Cnidaria) of Salento, Italy with notes on their life-cycles: an illustrated guide, Zootaxa 3908 (1), pp. 1-187 : 30-32

Eudendrium moulouyensis Marques, Pena Cantero and Vervoort, 2000

Fig. 19 A–F

See Schuchert (2008b) for a complete synonymy.

Material examined. HCUS-S 0 23 and HCUS-S 0 24 (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula).

Description (based on our own observations; Marques et al. 2000a; De Vito et al. 2008; Schuchert 2008b):

Hydroid. Hydrorhiza stolonal; colonies erect, minute; hydrocaulus monosiphonic, sometimes moderately polysiphonic (2–4 tubes) at base, up to 20–90 mm high, fragile , rarely branched in an irregular plane up to second order over its whole extension, perisarc delicate and thin, often with 3–4 annulations at the origins of hydrocladia, sometimes 1–2 perisarc rings beneath the hydranth, annulations can be found also in large colonies along the main stem and throughout the hydrocladia, colonies collected from the deepest levels of the species distribution (25–30 m depth) with few or no perisarc annulations along the main stem; hydranths on pedicels arising directly from main stem,, with a ring of glandular cells at the base of large hydranths, this region without nematocysts, with zooxanthellae in hydranth body and coenosarc; hypostome large; 22–28 filiform tentacles arranged in one whorl. Gonophores as fixed sporosacs; females oval, up to 5–6, born originally in a single whorl in the middle of a hydranth body (gonozooids) with a distinct hypostome but fewer and shorter tentacles than the gastrozooids, spadix simple, thick and unbranched, entirely clasped around the egg until a late stage of differentiation; males develop in high number (8–10 per gonozooid), usually with 2 spermatic chambers, sometimes three, on partially reduced zooids. Colours: perisarc brownish to yellowish; hydranths whitish to brown.

Cnidome. Heterotrichous microbasic euryteles can be found in two sizes: numerous large microbasic euryteles (15–16 x 8–10 µm), bean-shaped, densely distributed on the whole hydranth body, loosely occurring also on hypostome, and small microbasic euryteles (6– 8 x 3–4 µm), oval, on tentacles and hydranth. Both types can be also found scattered throughout the coenosarc in the stem and the hydrorhiza, sites of cnidoblast differentiation.

Habitat type. On shallow (from about 1 to 15 m) subhorizontal substrates characterized by photophilic algae or pre-coralligenous assemblages ( Marques et al. 2000a; Peña Cantero & García Carrascosa 2002; De Vito et al. 2008; Puce et al. 2009).

Substrate. Epilithic or epibiontic on different organisms with variable calcium carbonate content, such as red coralline algae ( Peyssonnelia spp.), green algae (Udothea sp. and Halimeda sp.) and calcified bryozoans, but also on artificial substrates such as fishing lines, plastic pieces and iron.

Seasonality. Throughout the whole year ( De Vito et al. 2008; Puce et al. 2009).

Reproductive period. Sexual reproduction in Adriatic populations was recorded in winter–spring months; in Salento waters ( De Vito et al. 2008) from December to May; in the Ligurian Sea from September to December (Puce et al. 2009).

Distribution: endemic to the Mediterranean Sea, perhaps also southern Brittany ( Castric et al. 1987, as Eudendrium hargitti ; Bouillon et al. 2004; De Vito et al. 2008; Gravili et al. 2008a).

Records in Salento. Common at: Otranto (De Vito 2006; Gravili 2006; De Vito et al. 2008; Gravili et al. 2008a); Torre Lapillo, Torre dell’Inserraglio ( Andreano 2007); La Strea (Porto Cesareo) ( Ventura 2011).

Remarks. This species is very similar to Eudendrium ramosum (except for the zooxanthellae) (see Schuchert 2008b). Castric et al. (1991) included in their list of Brittany’s hydroids a zooxanthellate Eudendrium hargitti colony that, according to the identification made by Picard (1950), could also belong to this species (see Schuchert 2008b). According to De Vito et al. (2008) all records of Eudendrium hargitti / Myrionema amboinense in the Mediterranean Sea ( Picard 1958a; Marinopoulos 1981, 1992; Piraino et al. 1999) should be regarded as doubtful and a re-examination of available material would be required. De Vito et al. (2008) noted that most polyps from the Otranto Channel and other Mediterranean localities, possessed concretions of unknown nature, packed between bases of each tentacle pair, or scattered along the hydranth body or on the perisarc of the stem: these bodies resemble large, spumous cells.

References. Marques et al. (2000a), Peña Cantero & García Carrascosa (2002), De Vito (2006), Gravili (2006), De Vito et al. (2008), Gravili et al. (2008a), Puce et al. (2009).

Figures

FIGURE 19. Eudendrium moulouyensis: A, colony silhouette; B, drawing of terminal hydrocladia with three hydranths; C, undischarged large microbasic euryteles; D, mature male gonozooid; E, mature female blastostyle (D, E same scale bar); F, drawing of gastrozooid polyp, showing the homogeneous dense distribution of large microbasic euryteles (capsule size in scale) on the hydranth body, and on the hypostome, and the presence of concretions between tentacle bases, hydranth body, and perisarc (drawn by C. G. Di Camillo). Scale bars: A, 1.0 cm; B, 1.0 mm; C, 20 µm; D, E, 0.2 mm; F, 300 µm.