Halecium banzare, Watson, 2008

Watson, Jeanette E., 2008, Hydroids of the BANZARE expeditions, 1929 – 1931: the family Haleciidae (Hydrozoa, Leptothecata) from the Australian Antarctic Territory, Memoirs of Museum Victoria 65, pp. 165-178 : 167-168

Halecium banzare sp. nov.

Figure 3A-F

Holotype NMV F147450, Station 41 , three microslides displaying branch fragments; also preserved male colony. Paratypes NMV F147451, Station 34, one microslide displaying one branch. NMV F147452, Station 107, one microslide displaying small branch fragment; preserved fragmented female stem or branch 70 mm long. NMV F147479, Station 107, one microslide displaying small branch fragment. NMV F147455, Station 107, two microslides displaying branch fragments; a small fragmented preserved colony. NMV F147479, one microslide displaying small branch fragment .

Diagnosis. Colonies originally 80 - 140 mm high, the tallest stem arising from a tufted hydrorhiza of thin, tangled, shining stolons. Stem thick, brittle, branched, heavily fascicled; polysiphonic tubes parallel, running almost to top of stem, along primary branches and along some secondary branches. Primary branches long, held out stiffly more or less in plane almost perpendicular to stem, succeeding branches in three or four orders; new branches given off from a hydrophore or from within a hydrotheca, typically long, monosiphonic, thin and flaccid with one to three deep basal annulations. Monosiphonic branch internodes moderately long, cylindrical, walls smooth, widening distally to hydrophore, nodes deeply indented, oblique to transverse, typically one or two constrictions above and below node.

Hydrophores alternate, distal on internode and directed outwards, projecting above level of node, walls cylindrical, smooth, abcauline wall often faintly bulging, adcauline wall slightly concave, often an internal thickening in perisarc about two thirds distance up wall, joining abcauline wall with a faint diagonal line in perisarc. Hydrotheca shallow, expanding a little from diaphragm to margin; rim circular, weakly everted. Diaphragm distinct, transverse, a row of desmocytes just above. Secondary hydrophores common, arising from diaphragm of hydrotheca, a transverse constriction in perisarc of secondary hydrophore just above rim ofhydrotheca.

Gonothecae of both sexes inverted conical, compressed, borne prolifically on younger branches, inserted without distinct pedicel in wall of hydrophore or lower down on internode; male gonotheca with a minute apical peak (visible only in side view), female similar in shape to male, gonophore containing large scattered ova; gonophores of both sexes with an apical pad of tissue. No visible aperture in either sex.

Perisarc of fascicled stem and branches firm, thinner on monosiphonic branches, very thin on gonotheca.

Colour of lower stem pale honey-brown, becoming paler distally, apex of stem and monosiphonic branches colourless.

Measurements (μm) Remarks. Although now much fragmented, the colonies were probably tall and sparsely branched, arising from a thick, mattedhydrorhiza.Internalthickeningof theperisarcispresent in many hydrophores. The ova are scattered, not clustered around the spadix of the gonophore. Both sexes appear to be near maturity but as none of the gonothecae show any sign of anapertureitseemslikelythatreproductivematerial isreleased by rupture of the very thin perisarc.

The outwardly directed hydrophores and hydrothecae are structurally similar to those of Halecium antarcticum Vanhöffen (1910) . However, according to Totton (1930), colonies of that species from McMurdo Sound were only 30 mm high, straggling, lightly fascicled, and with anastomoses, unlike the robust habit of H. banzare . Afurther important distinction is the much shallower hydrotheca in H. banzare which is only half as deep as that of H. antarcticum .

Etymology. The species name commemorates the BANZARE expedition.

Figures

Figure 3. A - F. Halecium banzare sp. nov. A, branch from holotype. B, part of branch from holotype. C, D, hydrophores from paratype. E, male gonotheca from holotype. F, (NMVF 147452) female gonotheca. Scale bar: A, 50 mm. B, 1 mm. C, 0.3 mm. D-F, 0,.5 mm.