Halopteris infundibulum Vervoort, 1966

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 : 51-52

Halopteris infundibulum Vervoort, 1966 ( Fig. 8 ; Table 8)

Halopteris infundibulum Vervoort, 1966:133 , fig.36a-d.— Schuchert 1997: 121, fig. 44a-d. — Vervoort & Watson 2003: 359, fig. 87C-J.

MATERIAL EXAMINED. — New Caledonia. BIOCAL 1, stn DW 36, 23°08.647’- 23°08.900’S, 167°10.994’- 167°11.296’E, 650-680 m, 29.VIII.1985, 1 colony with 2 immature gonothecae ( MNHN).

DISTRIBUTION. — This species is known from the Tasman Sea (42°10’S, 170°10’E) at 610 m depth ( Vervoort 1966), and from New Zealand waters south of 43°S, depth 512-1006 m. Our material comes from a single station in the New Caledonia area, collected between 650 and 680 m depth.

DESCRIPTION

Colony with a hydrorhiza composed of perisarcal fibres attached to substratum, from which rises a monosiphonic hydrocaulus. Nevertheless, basal part of colony shows several secondary tubes.

Hydrocaulus unbranched, with basal part divided into ahydrothecate internodes by transverse nodes as the result of regeneration processes after damage; last node with 14 frontal nematothecae in two longitudinal rows, separated from remain- der of stem by a hinge-joint. First hydrothecate internode, delimited by hinge-joints, bearing 10 nematothecae: one infracalycine, two pairs of laterals and five supracalycine in two rows; without lateral apophyses. Remainder of stem with hydrothecae, nematothecae and lateral apophyses but not divided into internodes. Cauline hydrothecae not strictly in one line, but slightly displaced towards hydrocladial apophyses, not as deep as hydrocladial hydrothecae and flanked by two pairs of lateral nematothecae; between two consecutive hydrothecae there are two mesial nematothecae. Apophyses short, without nematothecae, placed besides cauline hydrothecae and alternately directed left and right, except in second cauline hydrotheca where they are opposite

Hydrocladia inserted on lateral apophyses next to cauline hydrothecae. First hydrocladial internode short, ahydrothecate, without nematothecae, with basal transverse and distal oblique node. Remainder of hydrocladium unsegmented; only a weak trans-

BIOCAL 1 stn DW 36

Height of colony (in mm) 30

Axial segments:

Length

Diameter at node 220-380

Cauline hydrotheca:

Length 180-210

Diameter at rim 220-230

Hydrocladial internode:

Length 760-940

Diameter at node 90-150

Hydrotheca:

Length abcauline wall 330-370

Length adnate part adcauline wall 230-270

Length free portion adcauline wall 100-130

Diameter at rim 280-310

Lateral nematotheca (long pair):

Length 200-270

Diameter at rim 50-55

Lateral nematotheca (short pair):

Length 80-110

Diameter at rim 50-60

Gonotheca*:

Length 420-450

Maximum diameter 220-240

verse node above a hydrotheca can occasionally be found, usually in distal parts of hydrocladia. Each hydrocladial internode, when visible, with one hydrotheca and six nematothecae: two median inferior and two pairs of lateral nematothecae. Hydrothecae almost cylindrical, deep, with ¾ of adcauline wall adnate and abcauline wall almost straight. Mesial inferior nematothecae with apical chamber (slightly) lowered on adcauline side. First pair of lateral nematothecae on well-developed apophyses, long, slightly curved and surpassing the hydrothecal rim; basal chamber much longer than distal one, rim of apical chamber slightly lowered at side close to hydrotheca. Second pair of lateral nematothecae inserted on base of apophyses, small and with the rim of apical chamber deeply scooped. All nematothecae are bithalamic and movable.

Two immature gonothecae inserted at hydrothecal base by one-segmented pedicel, cone-shaped, and with one or two nematothecae on basal part; apical chamber of nematothecae lowered at side close to gonotheca.

VARIABILITY

Once three nematothecae were observed between two successive axial hydrothecae.

REMARKS

Material from New Caledonia shows the first axial internode limited by oblique nodes (hinge-joints),but it agrees with the type material of Halopteris infundibulum in all morphological characters of trophosome, gonosome and also with the measurements.

Figures

FIG. 8. — Halopteris infundibulum Vervoort, 1966, BIOCAL 1, stn DW 36: A, colony, frontal view; B, fragment of colony with immature gonotheca, latero-frontal view; C, basal internodes of stem, latero-frontal view; D, internodes from distal part of hydrocladium, lateral view; E, internodes, frontal view; F, immature gonotheca. Scale bars: A, 1 cm; B-E, 0.2 mm; F, 0.1 mm.