Halecium delicatulum Coughtrey 1876

Halecium delicatulum Coughtrey, 1876

Figure 5A-B

Halecium delicatulum Coughtrey, 1876a: 299.- Coughtrey 1876b: 26, pl. 3, figs 4–5.- Stechow, 1913a: 144.- Stechow, 1913b: 9, 79.- Stechow, 1923b: 5.- Bale, 1924: 235.- Ralph, 1958: 334, figs 11e, h-n, 12 a-p.- Pennycuik, 1959: 173.- Yamada, 1959: 31.- Leloup, 1960: 218, fig. 1.- Naumov and Stepanjants, 1962: 94, figs 16–17.- Rees and Thursfield, 1965: 106.- Millard, 1966a: 464, fig. 10L. - Ralph, 1966: 158.- Blanco, 1968; 203, pl. 1, figs 14–18, pl. 2, figs 1–3.- Millard, 1968: 253, 256.- Day et al,. 1970: 12.- Patriti, 1970: 23, fig. 21.- Blanco and Bellusci de Miralles, 1972: 7, figs 3–5.- Naumov and Stepanjants, 1972: 34, 52.- Stepanjants, 1972: 72.- Vervoort, 1972 a: 27, figs 4–5.- Vervoort, 1972 b: 341, fig. 2a.- Morton and Miller, 1973: 152, fig. 54.10.- Watson, 1973: 166.- Leloup, 1974: 10.- Millard, 1975: 145, fig. 47F–L.- Watson, 1975: 159.- Gordon and Ballantine, 1977: 100.- Millard, 1977a: 7, fig. 1C–D.- Stepanjants, 1979: 105, pl. 20, fig. 4A–V.- Watson, 1979: 234.- Hirohito, 1983: 5, 11.- Rho and Park, 1983: 41, pl. 2, figs 1–3.- Blanco, 1984c: 262, figs 1–6.- Blanco 1984d: 271, figs 3–5.- Rees and Vervoort, 1987: 25, fig. 5.- Staples and Watson, 1987: 218.- Ramil, Blanco and Iglesias Diaz, 1988: 72, fig. 2.- Gili et al., 1989: 78, fig. 7B.- Altuna and García Carrascosa, 1990: 54 et se q.- Genzano, 1990: 38, figs 2–5.- El Beshbeeshy, 1991: 32, figs 4a, 4b.- Park, 1991: 544.- Roca et al., 1991: 70.- Genzano and Zamponi, 1992: 40, fig. 17.- Park, 1992: 286.- Ramil and Vervoort, 1992 a: 82, fig. 20a-c.- Branch and Williams, 1993: 11.- Watson, 1994a: 66.- Altuna Prados, 1995: 54.- Bouillon et al., 1995: 45.- Hirohito, 1995: 20, textfig. 5a-c, pl. 1, fig. C.- Park, 1995: 10.- Genzano, 1996 a: 290 et se q.- Medel and Vervoort, 2000: 12 (cum sy n.).- Vervoort and Watson, 2003: 88, fig.16 A-E.

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

Halecium gracile Bale, 1888: 759, pl. 14, figs 1–3 (not Halecium gracile Verrill, 1873: 729).

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

Material examined. NMV F147459, Station 97, one microslide displaying a branch fragment; some preserved material. NMV F147460 Station 98, one microslide displaying two branches. NMV F147461, Station 103, eleven microslides displaying branches from male colony; some preserved material. NMV F14762, Station 107, one microslide displaying a branch. NMV F147477, two microslides displaying branch fragments.

Description. Stems to 10 mm long, taller stems fascicled, arising from tangled tubular hydrorhizal stolons. Younger stems monosiphonic, flexuous. Basal cauline internodes with several deep proximal corrugations, internodes thereafter smoother, long, cylindrical, tending to become sympodial in older stems; nodes distinct, oblique to transverse, one to three shallow annulations in perisarc above and below node. Hydrophores alternate, one distal on each primary cauline internode sloping outwards from node, contiguous with direction of internode; hydrophores variable in length, walls cylindrical, smooth; branches when present, given off from below primary hydrophore.

Hydrothecae moderately deep, walls outwardly curved, margin circular, wide, rim strongly outrolled; margins not replicated. Diaphragm distinct, transverse to shallow funnelshaped, usually a distinct row of desmocytes above.

Hydrophores arising up to five linear in series; variable in length, each arising from diaphragm of preceding hydrotheca, typically becoming shorter along the series; proximal walls of younger hydrophores often weakly undulated.

Colonies dioecious; gonotheca inserted without distinct pedicel in internode or hydrophore; immature gonothecae of both sexes balloon-shaped, compressed, developing gonophores in all samples immature, surmounted by an apical pad of tissue.

Hydranth with c. 24 tentacles.

Perisarc of stems moderately thick, thinner on gonothecae.

Measurements (μm)

Internode length 941 – 1,078 width at node 74 – 111 Hydrophore length (abcauline) of primary 198 – 988 length of succeeding hydrophores 78 – 387 Hydrotheca depth, margin to diaphragm 43 – 82 diameter at margin 179 – 211 diameter of diaphragm 94 – 129 Gonotheca Length 537 – 672 Apical (maximum) width 435 – 577

Remarks. The gonophores in most samples are immature, those on only one stem showing developing ova.

Distribution. Circumglobal in tropical, subtropical, and boreal waters. Recorded at all depths to 2,250 m. It is sometimes considered conspecific with Halecium antarcticum Vanhöffen, 1910, and with H. mediterraneum Weismann, 1883, the former reported from isolated Antarctic localities and the latter from many Mediterranean Sea localities (Vervoort and Watson 2003). Such wide latitudinal and bathymetric distribution may indicate that several morphologically similar species are possibly lumped together as H. delicatulum.