Plumularia sp. 1

Agís, José Ansín, Vervoort, Willem & Ramil, Fran, 2014, Hydroids of the families Kirchenpaueriidae Stechow, 1921 and Plumulariidae McCrady, 1859 (Cnidaria, Hydrozoa) collected in the Western Pacific Ocean by various French Expeditions, Zoosystema 36 (4), pp. 789-840 : 830-831

Plumularia sp. 1

( Fig. 25 ; Table 16)

MATERIAL EXAMINED. — Norfolk Ridge. SMIB 4 , stn DW 57, 23°21.5’- 23°21.0’S, 168°04.6’- 168°04.5’E, 210-260 m, 09.III.1989: many c. 30 mm high plumes on shell fragments ; no gonothecae ( MNHN). — SMIB 5 , stn DW 101, 23°21.2’S, 168°04.9’E, 270 m, 14.IX.1989: Bunch of c. 10 stems, up to 30 mm high, no gonothecae ( MNHN) .

DISTRIBUTION. — Known only from Norfolk Ridge, between 210-270 m depth.

DESCRIPTION

Hydrorhiza tubular, attached to sponge, supporting various monosiphonic, unbranched hydrocauli. Hydrocaulus divided into internodes by straight nodes. Basal part of hydrocaulus, below first apophyses, with two rows of nematothecae. Remainder stem internodes all have one distal apophysis and one to four nematothecae between two consecutive apophyses of the same side. Apophyses alternately directed left and right, with a small opening as a mamelon on superior surface and three nematothecae: two axillary and one above; one perisarcal ring sometimes appears at distal end.

Hydrocladia arranged left and right, slightly frontally in the basal half and gradually put almost frontally in the younger parts. Hydrocladia begin with an athecate internode with one nematotheca in the middle and a perisarcal ring at each extremity. Remainder of hydrocladium a succession of thecate and athecate internodes, separated by oblique nodes; thecate internodes with basal oblique and distal slightly oblique node, athecate internodes reverse. Thecate internodes with one hydrotheca on basal half of internode and four nematothecae: one mesial inferior, two laterals and one supracalycine. Hydrotheca cup-shaped, adcauline wall fully adnate, abcauline wall straight, hydrothecal aperture slightly tilted downwards, rim smooth. All nematothecae bithalamic, movable and conical. Lateral nematothecae are bigger than mesial. Thecate internodes also with two internal perisarc rings at both extremities. Athecate internodes with one nematotheca approximately halfway their length and two internal thickenings, one basal and one distal.

Gonothecae have not been observed.

VARIABILITY

Material from stn DW 57 and stn DW 101 sometimes having thecate internodes without suprahydrothecal nematothecae, and consecutive athecate internodes with two nematothecae; this distribution of nematothecae was always seen after damage and subsequent regeneration.

REMARKS

This species approaches Plumularia setacea ( Linnaeus, 1758) , but it differs by the presence of a suprahydrothecal nematotheca.

The absence of gonothecae prevents us from a more precise identification.

Figures

FIG. 25.— Plumularia sp.1, SMIB 5, stn DW 101:A, colony;B, internode of stem with apophyses;C, internodes basal part of hydrocladia; D, E, internodes apical part of hydrocladia. Scale bars: A, 1 cm; B-E, 0.1 mm.