Eudendriidae L. Agassiz, 1862

Cantero, Álvaro Luis Peña, 2024, New Insights into the Biodiversity of Benthic Hydroids (Cnidaria, Hydrozoa) from Seamounts in the Remote Macquarie Ridge, with the Description of Three New Species, Zoological Studies 63 (17), pp. 1-25 : 4

Family Eudendriidae L. Agassiz, 1862 Eudendrium sp.

Material examined: Stn 98, numerous monosiphonic stems up to 70 mm high, with gonophores, in very poor condition, growing on the axis of a gorgonian ( NIWA 114752).

Description: Monosiphonic stems up to 70 mm high, scarcely branched (up to second-order branches present). Perisarc dark brown, fading to light brown distally, and smooth, except for a few rings at origin of stems, branches and pedicels. No polyps present, but remnants of a few mature female gonophores observed.

Remarks: The material is unidentifiable, as it is in very poor condition, devoid of polyps and with only remnants of a few mature female gonophores. Regarding the cnidome, only a few empty capsules could be observed, some 9−10 × 3−3.5 µm and one 20 × 10 µm.

Watson (2003) reported four species of Eudendrium Ehrenberg from the area, only two of which have monosiphonic stems, Eudendrium deforme Hartlaub, 1905 , with stems up to 70 mm high, and Eudendrium macquariensis Watson, 2003 , with stems up to 7 mm high. According to this, the present material would be closer to the former.

Ecology and distribution: The material was collected from Seamount 9 Hjort, south of Macquarie Island, at a depth of 676− 750 m.