Antennella varians ( Billard, 1911 )

Agís, José Ansín, Vervoort, Willem & Ramil, Fran, 2009, Hydroids of the family Halopterididae (Cnidaria, Hydrozoa) collected in the western Pacific by various French expeditions, Zoosystema 31 (1), pp. 33-61 : 36-39

Antennella varians ( Billard, 1911) ( Fig. 1 ; Table 2)

Plumularia varians Billard, 1911: 62 , fig. 2. — Van Praët 1979: 930, fig. 72A-C.

Antennella varians – Billard 1913: 11, fig. 4A-E, pl. 1, figs 5, 8. — Rees & Vervoort 1987: 117, fig. 23c, d. — Schuchert 1997: 32, figs 10a-f, 11a-f.

Antenella varians – Hirohito 1969: 24, fig. 17.

MATERIAL EXAMINED. — New Caledonia. MUSORSTOM 5, stn DC 388, 20°45.35’S, 160°53.69’E, 500-510 m, 22.X.1986, bunch of unbranched hydrocladia arising from small tuft of fibres, with female and male gonothecae ( MNHN).

DISTRIBUTION. — Antennella varians was collected from various localities in the eastern part of the Malayan Archipelago ( Billard 1913), from several Japanese localities ( Hirohito 1969), from Zanzibar ( Rees & Vervoort 1987) and from Madagascar ( Schuchert 1997). The depth range varies between 16 and 165 m.

The material examined was collected at a single station near New Caledonia, between 500 and 510 m.

DESCRIPTION

Colonies with numerous unbranched stems arising from a tubular hydrorhiza attached to substrate.

Basal part of stem divided into several ahydrothecate internodes by transverse nodes, with exception of an ultimate, strongly oblique node. Each internode with variable number of nematothecae in two rows. First hydrothecate internode separated by strongly oblique nodes (hinge-joints), remainder of stem undivided although sometimes, after damage and subsequent regeneration, a well-marked oblique node was observed.

Hydrotheca cup-shaped in lateral view, abcauline wall straight and slightly thickened, adcauline wall fully adnate, rim smooth, perpendicular to axis or slightly tilted towards adcauline side. Two pairs of lateral nematothecae, one pair placed at end of well-developed apophyses, long and conical. Second pair of lateral nematothecae smaller, inserted on base of apophyses, with slightly scooped rim of apical chamber; both pairs of lateral nematothecae surpassing the hydrothecal rim. Between two consecutive hydrothecae, two to five mesial nematothecae arranged in two frontal rows at first and second hydrothecate internode and in a single row in the remaining internodes; adcauline wall of upper chamber slightly scooped. All nematothecae bithalamic and movable.

Gonothecae inserted at hydrothecal base, between the two rows of mesial nematothecae. Gonothecae of both sexes on same stem, female gonotheca distal to male ones. Female gonotheca sack-shaped with distal end truncated and large terminal aperture; two nematothecae near base. Male gonotheca smaller, ovoid, with circular aperture closed by a lid and basal part with two nematothecae; one male gonotheca without nematothecae. Nematothecae on gonothecae of both sexes bithalamic, movable and with rim of apical chamber slightly scooped at sides adjacent to gonotheca.

REMARKS

Antennella varians is considered a variable species by Rees & Vervoort (1987). Variations described by Billard (1913) were related to the length of hydro- and nematothecae and the position of the hydrothecal rim, perpendicular or oblique to stem. Later, Rees & Vervoort (1987) found in material of the John Murray expedition, a strong development of apophyses of the lateral nematothecae, specimens with a mesial nematotheca under each hydrothecae and the absence on the first hydrothecate internodes of a pair of hinge-joints.

Our material also shows some variations. The arrangement of nematothecae in a double row is only visible on the first or sometimes second hydrothecate internodes.The male gonothecae have normally two nematothecae; only one, probably an immature male gonotheca, is devoid of nematothecae and agrees with the putative male gonothecae described by Schuchert (1997: 33, fig. 10f).

The other morphological characters of the New Caledonian material agree with the available descriptions of Antennella varians . Therefore we included the present material in this species.

Figures

FIG. 1. — Antennella varians (Billard, 1911), MUSORSTOM 5, stn DC 388: A, colony; B, internodes from middle of hydrocladia, lateral view;C, internode,frontal view;D, female gonotheca,frontal view; E, female gonotheca,lateral view;F, male gonotheca,latero-frontal view. Scale bar: A, 1 cm; B-E, 0.2 mm; F, 0.1 mm.