Eudendrium deforme Hartlaub, 1905

Watson, Jeanette W., 2003, Deep-water hydroids (Hydrozoa: Leptolida) from Macquarie Island, Memoirs of Museum Victoria 60 (2), pp. 151-180 : 153-154

Eudendrium deforme Hartlaub

Figures 3A–D

Eudendrium deforme Hartlaub, 1905: 508 , 514, 552, figs B', C'.—

Bedot, 1925: 184.

Material examined. Stn 44, NMV F91308, many sparsely fertile colonies on dead stem of a primnoid gorgonian, colonies intergrown and entangled with Tulpa diverticula , sertularian and Eudendrium colonies, specimen alcohol-preserved. Stn 46, TM K2770, many colonies on dead stem of primnoid gorgonian, specimen alcohol-preserved.

Description. Colonies comprising many tangled stems up to 70 mm long and 0.3–0.4 mm diameter arising from a hydrorhiza entwining stem of host. Stems more or less straight to curved, monophonic, with 5–10 strong basal annulations and groups of annulations at intervals along stems.

Stems sparsely, alternately, but irregularly branched, more or less in one plane, occasionally secondary branching occurs; branchlets (pedicels) more or less alternate, spaced well apart, short to moderately long, beginning with up to 10 deep annulations; stems sometimes annulated throughout; perisarc otherwise smooth. A few hydranths in poor condition remain on colonies; hydranth large, with c. 24 tentacles. Perisarc of lower stems thick and smooth, thinning distally along smaller branches and pedicels.

Nematocysts all undischarged euryteles of one size: small, droplet-shaped, a few in coenosarc of stems and tentacles of hydranth, capsule 10 X 6 µm.

Male gonophores present on several colonies; clustered on short, smooth to corrugated pedicels near base of stems; up to 5 in a beaded chain, apical gonophore single, gonophores below paired; tentacles of hydranth partially resorbed and reduced in number, hypostome intact.

Colour. Lower stem shining in dark brown, fading distally to pale yellowish; gonophores white.

Distribution. Calbuco, Chile; Mar del Plata, Argentina ( Hartlaub, 1905).

Remarks. Due to entanglement of the stems it is difficult to decide if one or many colonies are present. The few hydranths are in very poor condition, due either to damage during collection or senescence of the colony. The species is distinguished by its strictly monosiphonic, shining brown stems and paired chain of immature gonophores.

Although Hartlaub’s description of the species is brief I have no doubt that the present specimens are referrable to Eudendrium deforme . Like much of the present material, Hartlaub’s specimens apparently comprised bare stems lacking hydranths or reproductive structures. The thin brown stems, as described and figured by Hartlaub are characteristic. The species has not been recorded since its first description.

Figures

Figures 3A–G. A, Eudendrium deforme. A, part of colony on dead branch of primnoid gorgonian, stn 46. B, single stem. C, cluster of male gonophores with paired immature gonophores and partially resorbed tentaclesof hydranth. D, undischarged nematocyst, probably eurytele from coenosarc of stem. E–G, Eudendrium macquariensis sp. nov., stn 44. E, stems from holotype colony on Eudendrium deforme. F, undischarged nematocyst from tentacles. G, undischarged nematocyst, site unknown. Scale bar: A, 25 mm; B, 10 mm; C, 0.5 mm; E, 1 mm; F, G, 10 µm.