Antennella megatheca, Agís & Vervoort & Ramil, 2009

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 : 39-41

publication ID	https://doi.org/ 10.5252/z2009n1a3
persistent identifier	https://treatment.plazi.org/id/038E87B3-965D-FFEC-ED38-FB7DACCD4C42
treatment provided by	Marcus
scientific name	Antennella megatheca
status	sp. nov.

Treatment

Antennella megatheca n. sp.

( Fig. 3 View FIG ; Table 4)

TYPE MATERIAL. — New Caledonia. BIOCAL 1, stn DW 38, 22°59.74’S, 167°15.31’E, 360 m, 30.VIII.1985, 1 colony with 7 stems, no gonothecae, holotype ( MNHN Hy 1295). — Stn DW 41, 22°45.133’- 22°45.129’S, 167°11.744’- 167°11.998’E, 380-410 m, 30.VIII.1985, 2 stems, no gonothecae, paratype (RMNH-Coel. 35230, slide 815).

ETYMOLOGY. — The species name megatheca refers to the big size of the hydrotheca.

DISTRIBUTION. — Material collected near New Caledonia between 360 and 410 m.

DESCRIPTION (HOLOTYPE)

Colony with seven stems arising, alternately directed left or right, from tubular stolon without nematothecae. Basal part of stem composed of two athecate internodes, the first short and separated by transverse nodes; the second long, with two or three frontal nematothecae and distal oblique node. Remainder of stem divided into hydrothecate and ahydrothecate internodes by well-marked oblique and weak straight nodes.

Hydrothecate internodes with basal oblique and distal straight node, one hydrotheca and three nematothecae: one mesial inferior and two laterals. Hydrotheca tubular, deep and of big size, walls straight (or nearly straight) and almost parallel; adcauline wall adnate for c. ⅓ its length, abcauline wall straight; hydrothecal rim smooth and lowered laterally. Mesial inferior nematotheca immovable, not reaching hydrothecal base; adcauline wall of upper chamber deeply scooped. Lateral nematothecae movable, placed on well-developed apophyses, one on each side, reaching middle of hydrothecae; rim of upper chamber rolled inwards and with a deep emargination on both sides.

Ahydrothecate internodes with one movable basal nematotheca; adcauline wall of upper chamber deeply scooped. All nematothecae are bithalamic.

Gonothecae absent.

VARIABILITY

Some stems show one or two frontal nematothecae (one basal and the other distal) in the first ahydrothecate internode. First hydrotheca of all stems with abcauline wall slightly convex in its basal part and concave below the margin ( Fig. 3B View FIG ).

REMARKS

This material is characterised by big and deep hydrothecae; the lateral nematothecae are inserted on well-developed apophyses with the upper chamber deeply scooped on both sides, and there is a single nematotheca on the ahydrothecate internodes.

The trophosome of Antennella megatheca n. sp. shows similarity with A. siliquosa (Hincks, 1877) , A. tubulosa (Bale, 1894) and A. kiwiana Schuchert, 1997 , but it differs by the great size of its hydro-

SMIB 4 stn DW 55

Maximum height of stem (in mm) 14

Length hydrothecate internode 410-500

Length ahydrothecate internode 410-710

Diameter at node 50-90

Hydrotheca:

Length abcauline wall 140-150

Length free portion adcauline wall 60-80

Diameter at rim 190-200

Mesial infracalycine nematotheca:

Length 120-150

Diameter at rim 35-50

Lateral nematotheca:

Length 75-100

Diameter at rim 50-60

Axillar nematotheca:

Length 60-70

Diameter at rim 25-30

Nematotheca of ahydrothecate internode:

Length 75-100

Diameter at rim 30-40

thecae (twice that of A. kiwiana and A. tubulosa ). In the presence of a single nematotheca on ahydrothecate internodes instead of two, this material also differs from A. siliquosa . The insertion of the lateral nematothecae on well-developed apophyses separates this species from A. tubulosa , where the apophysis is short or lacking.