Halecium delicatulum Coughtrey, 1876

Watson, Jeanette W., 2003, Deep-water hydroids (Hydrozoa: Leptolida) from Macquarie Island, Memoirs of Museum Victoria 60 (2), pp. 151-180 : 166-167

Halecium delicatulum Coughtrey

Figures 16A–C

Halecium delicatulum Coughtrey, 1876b: 299 .— Coughtrey, 1876a: 26, pl. 3 figs 4, 5.— Stechow, 1913: 144.— Stechow, 1913: 9, 79.— Stechow, 1923a: 5.— Bale, 1924: 235.— Ralph, 1958: 334, figs 11e, h–n, 12 a–p.— Pennycuik, 1959: 173.— Yamada, 1959: 31.— Naumov and Stepanjants, 1962: 94, figs 16, 17.— Rees and Thursfield, 1965: 106.— Millard, 1966: 464, fig. 10L. — Ralph, 1966: 158.— Millard, 1968: 253, 256.— Day et al., 1970: 12.— Blanco and Bellusci de Miralles, 1972: 7, figs 3–5.— Naumov and Stepanjants, 1972: 34, 52.— Stepanjants, 1972: 72.— Vervoort, 1972a: 27, figs 4, 5.— Vervoort, 1972b: 341, fig. 2a.— Watson, 1973: 166.— Leloup, 1974: 10.— Millard, 1975: 145, figs 47F–L.— Watson, 1975: 159.— Millard, 1977a: 7, figs 1C, D.— Millard, 1978: 193.— Stepanjants, 1979: 105, pl. 20 figs 4A–V.— Watson, 1979: 234.— Hirohito, 1983: 5, 11.— Rho and Park, 1983: 41, pl. 2 figs 1–3.— Aguirrezabalaga et al., 1984: 90.— Rees and Vervoort, 1987: 25, fig. 5.— Aguirrezabalaga et al., 1988: 222.— Ramil et al., 1988: 72, fig. 2; Gili, Vervoort, and Pagès, 1989: 78, fig. 7B.— Altuna and García Carrascosa, 1990: 54.— Genzano, 1990: 38, figs 2–5.— El Beshbeeshy, 1991: 32, figs 4a, b.— Roca et al., 1991: 70: 14.— Genzano and Zamponi, 1992: 40, fig. 17.— Park, 1992: 286.— Ramil and Vervoort, 1992: 82, figs 20a–c.— Branch and Williams, 1993: 11.— Genzano, 1994: 5.— Watson, 1994: 66.— Altuna Prados, 1995: 54.— Bouillon et al., 1995: 45.— Hirohito 1995: 20, figs 5a–c, pl. 1, fig. C.— Park, 1995: 10.- Genzano, 1996: 290.— Medel and Vervoort, 2000: 12.

Halecium flexile Allman, 1888: 11 , pl. 5 figs 2, 2a.

Halecium gracile Bale, 1888: 759 , pl. 14 figs 1–3

Halecium parvulum Bale,1888: 760 , pl. 14 figs 4, 5.

Material examined. Stn 122, NMV F91343, NMV F91344, malinol-mounted microslides, colony of three damaged infertile stems, on Eudendrium .

Description. Two stems simple, stolonal, the other, the tallest 16 mm high, lightly fascicled. Tubes of fascicled stem running about two thirds distance up stem; stem thereafter monosiphonic with a few alternate branches standing out stiffly almost at right angles to axis, smaller branchlets arising at intervals along stem. Monosiphonic branch internodes long, nodes oblique to almost transverse, sloping almost parallel to primary hydrophore, weakly to deeply constricted, deeper nodes with tumescence above and below. Hydrophores alternate, distal on internode, a smooth, outwardly directed continuation of internode.

Primary hydrophores variable in length, cylindrical, expanding a little to below hydrotheca, perisarc smooth; some older hydrophores on lower stem region deeply corrugated; a secondary hydrophore sometimes given off from primary; linear series of up to eight hydrophores common, each hydrophore arising from diaphragm of preceding one, usually a strong basal constriction present, successive hydrophores usually becoming progressively shorter. Hydrotheca moderately deep, expanding smoothly to a wide, strongly everted margin with outrolled rim; diaphragm very strong, transverse, some concave with central hydropore, usually a row of desmocytes above.

Perisarc of polysiphonic tubes of stem quite thick, thinning along monosiphonic branches and hydrophore, becoming thin at hydrothecal margin.

Colour. Clear white (preserved material). Measurements (µm)

Branch length of internode 549–765 width at node 109–152

Hydrophore adcauline length of primary, to diaphragm 78–117 length of succeeding hydrophores, base todiaphragm 78–312 diameter at diaphragm 137–164 depth, margin to diaphragm 32–59 diameter, marginal rim 220–257

Distribution. Circumglobal in tropical, subtropical and boreal waters ( Vervoort and Watson, 2003).

Remarks. The rather stiff mode of branching in the largest colony does not precisely accord with the usually rather lax habit of H. delicatulum (pers. obs.) but may be an artefact of preservation. Although the hydrothecae are a little shallower than is normal for H. delicatulum I have no doubt the present material is referrable to that species.

Figures

Figures 16A–C. Halecium delicatulum, stn 122. A, distal part of colony. B, monosiphonic branch. C, hydrophores, enlarged. Scale bar: A, 5 mm; B, 0.5 mm; C, 0.3 mm.