Lafoea tenellula Allman, 1877

Watson, Jeanette W., 2003, Deep-water hydroids (Hydrozoa: Leptolida) from Macquarie Island, Memoirs of Museum Victoria 60 (2), pp. 151-180 : 156-157

Lafoea tenellula Allman

Figures 6A–C

Lafoea tenellula Allman, 1877: 12 , pl. 8 figs 3, 4.— Ritchie, 1911: 820, pl. 88 fig. 5.— Stechow, 1913: 110.— Stechow, 1923a: 10.— Stechow, 1923b: 143.— Stechow, 1925: 453, fig. 23.— Leloup, 1940: 14.— Fraser, 1943: 90.— Fraser, 1944: 227, pl. 47 fig. 211.— Fraser, 1948: 232.— Deevey, 1954: 646.— Riedl, 1959: 646.— Yamada, 1959: 49.— Vervoort, 1968: 101.— Millard, 1973: 28.— Hirohito, 1995: 128, figs 36d–f.

Material examined. Stn 44, NMV F91312, specimen alcohol-preserved, NMV F91339, malinol mounted microslide of coppinia; fertile colonies on Eudendrium and on primnoid gorgonian. Stn 90, NMV F91333, malinol-mounted microslide, fragment detached from substrate. Stn 119, TM K2772, specimen alcohol-preserved, NMV F91334, malinol-mounted microslide, colony on Eudendrium . Stn 120, NMV F91313, sparingly fertile colony on Tulpa diverticula and Eudendrium , specimen alcohol-preserved.

Description. Hydrorhiza reptant on host hydroids, stolons crumpled, colony predominantly stolonal but sometimes a short length of stolon becoming free as an erect monosiphonic stem.

Hydrothecae given off irregularly in all directions from hydrorhiza; hydrothecae long, elongate conical, radially symmetrical, straight to faintly sinuous, no true pedicel but a tubular narrowing of hydrotheca. A faint transverse to slightly oblique ring of scattered punctae sometimes present marking distal junction of pseudopedicel with hydrotheca, sometimes a faint constriction in perisarc of hydrotheca at desmocyte ring. Margin transverse to hydrothecal axis, circular, rim weakly everted with up to seven, usually widely spaced, regenerations. Persiarc of hydrotheca moderately thick near base, thinning distally to margin. Hydranths not well preserved, deeply contracted into hydrothecae, but probably with eight to 10 tentacles.

Coppinia comprising a tightly packed circle of gonothecae seated on a thin, dish-shaped basal plate adherent to stem of hydroid host; protective nematophore tubules scattered in irregular groups around and throughout coppinia. Gonothecae small, crowded, flask-shaped, bases rounded, widening from base to shoulder, surmounted by a short tubular neck with transverse, slightly everted circular orifice; perisarc of gonothecae rather thin. Ovoid gonophores (or planulae) present in some gonothecae but too degenerate for description. Protective tubules varying in length from short to very long, tubular in section, single or bifid, some completely or partially conjoined proximally, straight or curved, narrowing from base to apex; terminal orifice circular; perisarc thick, usually smooth; some undulated; others showing scars from interruptions to growth.

Colour. Colonies and coppiniae transparent colourless; gonophores pale creamy white.

Measurements (µm)

Hydrorhiza diameter 68–88 Hydrotheca length of unregenerated hydrotheca 360–500

length of regenerated hydrotheca 1060–1440 width at puncta ring 76–112 diameter at margin 168–240 Coppinia overall length of gonotheca 320–440 maximum width of gonotheca 80–112 diameter of gonothecal orifice 48–60 length of nematophorous tubules 500–1700 width of tubule at base 96–104 diameter of orifice of tubule 48–56

Distribution. Australian east coast ( Ritchie, 1911), California ( Fraser, 1948), Carribean, West Indies ( Vervoort, 1968), Japan ( Hirohito, 1995). The geographical and bathymetric distribution of L. tenellula ranges from moderately deep tropical and temperate waters to deep subantarctic waters (this collection).

Remarks. The hydrothecae on younger parts of the colonies are less crowded than those on older regions. The hydranths are deeply contracted into the hydrothecae and the tentacles of reasonably well preserved ones appear to be enclosed in a sheath of tissue.

The present material generally matches the description, dimensions and figure of Lafoea tenellula given by Stechow (1925) for specimens from Madeira and the Canary Islands but conforms less well with the figure of hydrothecae given by Hirohito (1995) for the species from Japan.

Three coppiniae were found among colonies in the collection; one was attached to the stem of Eudendrium from Stn 119 and the others to a primnoid gorgonian stem (Stn 44). Because of intergrowth of the material with hydrorhizae of several other hydroid species the coppiniae are ascribed with some hesitation to L. tenellula , the gonosome of which is not known. Vervoort (1966) renamed L. tenellula recorded by Ritchie (1911) from off the Australian temperate east coast Hebella ritchei . I have examined Ritchie’s material and other Australian east coast specimens held in the Australian Museum, Sydney; as they are identical with the present specimen, Ritchie’s identification of L. tenellula is correct.

Figures

Figures 6A–C. Lafoea tenellula, stn 97. A, stolonal colony on branch of Eudendrium, hydrorhiza produced into free stolon. B, regenerated hydrotheca. C, longitudinal section through coppinia. Scale bar: A, 1 mm; B, C, 0.5 mm.