Hincksella neocaledonica, Galea, 2015

Galea, Horia R., 2015, Two new genera and nine new species of hydroids (Cnidaria: Hydrozoa) from off New Caledonia, European Journal of Taxonomy 135, pp. 1-19 : 15-16

Hincksella neocaledonica sp. nov.

urn:lsid:zoobank.org:act:69FDB75D-8E59-4CFB-9387-35B0C1B1D65F

Fig. 5 E–F; Table 3

Diagnosis

Stems simple, monosiphonic, divided into rather long internodes, each bearing a hydrotheca; the latter alternate, long, tubular, facing out- and upward; rim often renovated; surface of hydrotheca densely and finely striated.

Etymology

Named for its area of occurrence, New Caledonia.

Material examined

Holotype

NEW CALEDONIA: campaign Biocal, station DW46, 22°53’ S, 167°17’ E, 570–610 m, 30 Aug. 1985; 2.5 cm high, infertile stem devoid of hydrorhiza (IK-2012-10299).

Description

The 2.5 cm high stem fragment is devoid of its hydrorhiza and seems to have been broken off just above its origin from it. Monosiphonic throughout and unbranched; very basal part (ca. 2.5 mm long) ahydrothecate; remainder of stem divided into 21 moderately long, slender and geniculate internodes, by means of transverse nodes; perisarc of internodes smooth; a distally-placed hydrotheca per internode. Hydrothecae alternate, tubular, adnate for one-third of adcauline length, facing up- and outward, and oriented at an angle of c. 45° with internode; free adcauline wall nearly straight to imperceptibly convex; abcauline wall convex at inflexion point, then straight and parallel to its free adcauline counterpart; perisarc of hydrotheca finely and densely striated throughout; rim often renovated; aperture circular, perpendicular to long axis of hydrotheca. Gonotheca unknown. Large, parallel-walled macrobasic heteronemes (none seen discharged), with either straight or slightly curved axes and rounded ends, common in coenosarc.

Remarks

The alternate, long, tubular, non-operculate hydrothecae and the large nematocysts scattered in the coenosarc place this species, with little doubt, in the genus Hincksella Billard, 1918 . It superficially resembles H. pusilla (Ritchie, 1910) (see Galea & Ferry 2015 for taxonomical considerations) through the shape of its internodes and hydrothecae. However, Ritchie’s species is comparatively smaller ( Galea 2010: table 3) and the perisarc of its hydrothecae is smooth throughout.

Figures

Fig. 5. — A–D. Hincksella cornuta sp. nov. A. Basal portion of stem with hydro- and gonothecae. B. Hydrotheca. C. Detail of the foramen for the passage of the hydranth into hydrotheca. D. Gonotheca arising from within a hydrotheca. — E–F. Hincksella neocaledonica sp. nov. E. Portion of stem. F. Hydrotheca, showing outer striations. — G–H. Hincksella similis sp. nov. G. Portion of stem. H. Hydrotheca, showing extent of external striations. Scale bars: A, E, G = 1 mm; B, D, F, H = 500 μm; C = 200 μm.