Lafoea dumosa (Fleming)

Watson, Jeanette W., 2003, Deep-water hydroids (Hydrozoa: Leptolida) from Macquarie Island, Memoirs of Museum Victoria 60 (2), pp. 151-180 : 157-158

Lafoea dumosa (Fleming)

Figures 7A–E

Sertularia dumosa Fleming, 1820: 83 (nomen nudum).

Campanularia dumosa .— Fleming, 1828: 548–549.

Lafoea dumosa .— Hutton, 1904: 319.— Fraser, 1911: 51.— Billard, 1912: 464.— Stechow, 1912: 357.— Stechow, 1913: 30.— Fraser, 1914: 86.— Fraser, 1918: 333, 354.— Stechow, 1919: 80, fig. A1.— Fraser, 1921: 73.— Fraser, 1922: 5.— Stechow, 1923a: 10.— Billard, 1927: 331.— Fraser, 1927: 326.— Totton, 1930: 158, fig. 14.— Billard, 1931: 245.— Leloup, 1934: 8.— Fraser, 1935: 144.— Kramp, 1935: 123, figs. 52a, 53.— Fraser, 1937: 119–120, pl. 25 fig. 137.— Fraser, 1938: 110.— Fraser, 1939: 160.— Leloup, 1940: 14.— Vervoort, 1942: 285.— Fraser, 1944: 221, pl. 45 fig. 205, pl. 46 fig. 205.— Fraser, 1948: 229.— Teissier, 1950: 17.— Deevey, 1954: 270.— Hamond, 1957: 295, 307.— Ralph, 1958: 310.— Riedl, 1959: 646.— Yamada, 1959: 50.— Leloup, 1960: 221.— Naumov, 1960: 276, fig. 165.— Rees and Thursfield, 1965: 79.— Teissier, 1965: 19.— Redier, 1967: 389.— Vervoort, 1968: 100.— Calder, 1970: 1524, pl. 5 fig. 3.— Christiansen, 1972: 296.— Calder, 1975: 299, fig. 3D.— Cornelius, 1975: 385, fig. 4.— Millard, 1975: 185.— Millard, 1977a: 15.— Millard, 1978: 195.— García Corrales et al., 1979: 19, fig. 8.— Millard, 1980: 131.— Stepanjants, 1980: 116.— Hirohito, 1983: 6, 21.— Stepanjants, 1985: 127, 131.— Antsulevich, 1987: 49, fig. 11B.— Rees and Vervoort, 1987: 40, figs 7–8.— Cornelius, 1988: 76.— Llobet et al., 1988: 38, fig. 4E.— Gili, Murillo and Ros, 1989: 23.— Gili, Vervoort and Pagès, 1989: 73, fig. 3B.— Cornelius and Ryland, 1990: 135, fig. 4.13.— El Beshbeeshy, 1991: 84, fig. 20.— Peña Cantero, 1991: 70, pl. 5 figs a–d.— Calder, 1992: 1080.— Cornelius, 1992: 254, 257.— Ramil and Vervoort, 1992: 55.— Boero and Bouillon, 1993: 263.— Branch and Williams, 1993: 10.— Cornelius, 1995: 261, fig. 60.— Hirohito, 1995: 126, figs 36a–c, pl. 8 fig. A.—Medel and López–González, 1996: 198.— Peña Cantero and García Carrascosa, 1995: 23, figs 4A–D.— Stepanjants et al, 1996: 7.— Peña Cantero and García Carrascosa, 1999: 212.— Schuchert, 2000: 413.— Schuchert, 2001: 67, figs 54 A–D, 55, 56.

Lafoea?dumosa . — Ralph, 1958: 310.

Campanularia fruticosa M. Sars, 1850: 131 , 138.

Campanularia gracillima Alder, 1856: 361 , pl. 14 figs 5, 6.

Lafoea gracillima .— Ralph, 1958: 310, figs 1y, 2a–c.

Lafoea capillaris G.O. Sars, 1874: 115 , pl. 4 figs 4, 5.

Lafoea elegantula Broch, 1903: 5–6 , pl. 1, figs 5, 6, pl. 2, figs 7–9.

Material examined. Stn 44, TM K2773, NMV F91314, specimen alcohol-preserved. NMV F91340, malinol-mounted microslide from colony, abundant infertile colonies on primnoid gorgonian.

Description. Colonies arborescent, delicate and rather lax, the largest 25 mm high and 15 mm wide across the branches, stem 0.8 mm wide above base; smallest colonies 3–5 mm high. Hydrorhiza thread-like tubular stolons reptant on substrate; stolons bunched at base of complex colonies. Smallest stems monosiphonic, taller colonies with 2 or more polysiphonic tubes running up stem and along branches. Colonies branched at acute upward angles but in no particular order around stem; branches fascicled proximally, becoming monosiphonic distally, perisarc smooth without nodes. In proximal stem region of larger colonies tubes rather twisted, gradually becoming more or less parallel.

Hydrothecae given off from stem and branches, on monosiphonic branches (hydrocladia) arranged in whorls of three at an angle of c. 120° around hydrocladium, but occasionally an opposite pair; each hydrotheca well separated from its neighbour; in polysiphonic branches where hydrothecae given off from outer tubes of stem or branch this verticil arrangement obscured. Hydrothecal pedicel long, directed at an acute upward angle to hydrocladium, tubular, expanding distally to merge smoothly into hydrotheca, pedicel undulated with to 1–4 bends; a thin transverse line of punctae marking junction of hydrotheca with pedicel, a small annular internal ledge in hydrothecal wall at puncta line. Hydrothecae long, narrowly conical, widening smoothly to margin; body typically asymmetrically bent, adcauline side weakly convex in proximal third, then becoming almost straight or faintly sinuous to margin; abcauline side straight to weakly concave; both walls expanding a little below margin. Margin of hydrotheca circular, perceptibly everted but with no outrolling of rim; some hydrothecae with two or three marginal replications, basal-most replication typically at some distance below margin. Most hydrotheca contain remnants of hydranths with c. 12 tentacles.

Perisarc thickest on lower stem and branches, thinning distally along branches, hydrothecae very thin and smooth.

Colour. Colonies pale yellowish in lower regions, becoming translucent distally. Hydrothecae transparent, shining.

Measurements (µm)

Hydrorhiza width of stolon 88–120 Branch diameter of monosiphonic part 112–136

length from axil to first hydrotheca 680–720 Hydrotheca distance between successive hydrothecae on hydrocladium 240–464

length of pedicel to puncta line 240–280

diameter of pedicel 80–88

diameter at puncta line 96–112

length, puncta line to margin (including replications) 600–664

diameter at margin 176–232

Distribution. Near-cosmopolitan, in Atlantic, Pacific and Indian Oceans, Arctic and Antarctic, depth range from the sublittoral zone to deep sea ( Cornelius, 1995; Schuchert, 2001).

Remarks. The hydrothecal pedicels are bent rather than twisted or smoothly annulated with up to 4 kinks; the perisarc is smooth throughout. Most colonies are fascicled, only the very youngest and shortest being monosiphonic. Single hydrothecae are abundant on the hydrorhiza between complex stems. The colonies are quite lax and unable to support their weight out of fluid.

The present material conforms in most respects with earlier descriptions of Lafoea dumosa . It does, however, differ somewhat from most descriptions in having an almost invariable triseriate arrangement of the hydrothecae on monosiphonic hydrocladia, this condition usually being obscured in polysiphonic stems and branches, rather than the incipiently triseriate or multiseriate arrangement described by some authors.

Figures

Figures 7A–E. Lafoea dumosa, stn 44. A, colony. B, part of branch. C, hydrotheca with typically twisted pedicel and diaphragm. D, hydrotheca with replicated margin. E, radial arrangement of hydrothecae around stem. Scale bar: A, 10 mm; B, E, 1 mm; C, D, 0.5 mm.