Aglaophenia postdentata Billard, 1913

Galea, Horia R., 2010, Additional shallow-water thecate hydroids (Cnidaria: Hydrozoa) from Guadeloupe and Les Saintes, French Lesser Antilles, Zootaxa 2570, pp. 1-40 : 31

Aglaophenia postdentata Billard, 1913

(fig. 8A–F)

Aglaophenia postdentata Billard, 1913: 100 , fig. 89.― Jäderholm, 1920: 8, pl. 2, fig. 8.― Vervoort, 1941: 231.― Redier, 1966: 97, pl. 3, fig. 4.― Millard & Bouillon, 1973: 90, fig. 11G, H.― Ryland & Gibbons, 1991: 557, fig. 24A–D.―? Watson, 1994: 158, fig. 4C–H.―? Watson, 1996: 79, tab. 1.―? Watson, 2005: 563.

Aglaophenia pluma pluma ― Spracklin, 1982: 246, fig. 117I [not Aglaophenia pluma ( Linnaeus, 1758) ].

Material examined. Stn.19: 26.11.2009, 6–11 m—numerous sterile cormoids to 1 cm high, on Halimeda sp. and basal part of Eudendrium sp. (parts as MHNG-INVE-68733 and MNHN-IK.2009-828).

Remarks. This species is readily distinguished from its congeners by its delicate appearance, the shape of cormidia, the presence of ten hydrothecal cusps, and the opened corbula. For a good redescription of its trophosome, see Ryland & Gibbons (1991). The gonothecae were first described by Millard & Bouillon (1973).

The Australian specimens described by Watson (1994) differ in several respects from the previous accounts: 1) the anterior and posterior hydrothecal cusps were hypertrophied, the former being almost rectangular in frontal view, and the latter “much longer and arched inwards over the aperture, edges rolled upwards”; 2) the lateral nematothecae had a circular aperture, while normally they are gutter-shaped ( Billard 1913, Ryland & Gibbons 1911, present study fig. 8F1); 3) the corbulacostae were provided with a single basal (axillar) nematotheca, while two were found in the specimens studied by Millard & Bouillon (1973). This material is provisionally kept conspecific with Billard’s (1913) species, pending additional, broader studies on its intraspecific variability.

The specimen figured by Spracklin (1982, fig. 117I) has obviously ten hydrothecal cusps and the cormidium is quite long, as in the present specimens; it is here included in the synonymy of A. postdentata .

Schuchert (2003) remarked that only minor differences exist between A. postdentata and A. sibogae Billard, 1913 , and that more material of both species is needed to clarify their relationship.

Caribbean records. Belize ( Spracklin 1982, as A. pluma pluma ).

World distribution. Indonesia ( Billard 1913, Jäderholm 1920, Vervoort 1941), New Caledonia ( Redier 1966), Seychelles ( Millard & Bouillon 1973), Belize ( Spracklin 1982), Fiji ( Ryland & Gibbons 1991), south and western Australia ( Watson 1994, 1996, 2005). The present record is the first for the Atlantic Ocean.