Hincksella sibogae Billard, 1918

Galea, Horia R. & Schuchert, Peter, 2019, Some thecate hydroids (Cnidaria: Hydrozoa) from off New Caledonia collected during KANACONO and KANADEEP expeditions of the French Tropical Deep-Sea Benthos Program, European Journal of Taxonomy 562, pp. 1-70 : 19-20

Hincksella sibogae Billard, 1918

Figs 6B , 7 K–L; Table 3

Hincksella sibogae – Vervoort & Watson 2003: 245 , fig. 58D–E.

Material examined

PACIFIC OCEAN • two colonies without gonothecae, ca 9 cm high; one of them was cut into two pieces for convenient microscopical examination; off New Caledonia, stn DW4736; 22°42′ S, 167°41′ E; 303–308 m; 22 Aug. 2016; KANACONO leg.; a cladium from the same colony, containing remains of coenosarc, was removed for DNA extraction, DNA1368; voucher MHNG-INVE- 120802; barcode identifier MK 073092 ; MNHN-IK-2015-391 .

Remarks

The present material agrees well with the descriptions given by Billard (1925) and Vervoort & Watson (2003), and it is characterized by the following: a) the unbranched hydrocaulus is fascicled for most of its length; b) its main tube is undivided and has a regular structure, with equivalents of internodes composed of a basal cladial apophysis and its associated axillary hydrotheca, two alternate hydrothecae above, and a second cladial apophysis (on side opposite to preceding one) with its associated axillary hydrotheca; c) hydrocladia are simple and undivided into internodes, up to 1.3 cm long, and bear up to 13 alternate hydrothecae; the first internode is comparatively longer than subsequent ones and provided with a couple of proximal twists; ordinary internodes are moderately-long; d) the hydrothecae are immersed for about half their adaxial length into their corresponding internodes, and they narrow basally; their base is convex, entire, with occasional fenestrae below (as sites for the origin of gonothecae); e) the hydranth is attached to the lower third of the inner hydrothecal wall; f) the perisarc of the colonies is rather thin and easily collapsible, especially on hydrothecae.

Distribution

Indonesia, the Great Barrier Reef, Tasman Sea near Lord Howe Island ( Vervoort & Watson 2003), New Caledonia (present study).

Genus Synthecium Allman, 1872

Figures

Fig. 6. A. Hincksella immersa Galea, sp. nov., holotype colony, MNHN-IK-2015-390. — B. Hincksella sibogae Billard, 1918, one colony from sample MNHN-IL-2015-391. — C–F. Synthecium hians Millard, 1957, one colony from sample MNHN-IK-2015-494 (C) and detail of its fascicled base (D); individual stems diverging from common base (E) and fertile stem (F), both from sample MNHN-IK-2015-486. — G–H. Synthecium rectangulatum Galea, sp. nov., holotype colony (G) and gonothecae on proximal parts of the stems (H), both from sample MNHN-IK-2015-485. Scale bars: A–B, D–E = 1 cm; C, G = 2 cm; F, H = 5 mm.

Fig. 7. A–F. Hincksella immersa Galea, sp. nov., portion of stem with three cladia (A), four hydrothecae (B–E) showing varied degree of immersion, portion of cladium with gonothecae (F), all from sample MNHN-IK-2015-390. — G–J.? Hincksella neocaledonica Galea, 2015, portion of stem with three hydrothecae (G), immature gonotheca in frontal (H) and lateral (I) views, all from sample MNHN- IK-2015-384; fully-formed gonotheca (J) from sample MNHN-IK-2015-385. — K–L. Hincksella sibogae Billard, 1918, portion of colony showing branching pattern (K), three hydrothecae (L), all from sample MNHN-IK-2015-391. Scale bars: A, K = 1 mm; B–J, L = 500 µm.