Hincksella neocaledonica Galea, 2015

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 : 18-19

? Hincksella neocaledonica Galea, 2015

Fig. 7 G–J

Hincksella neocaledonica Galea, 2015a: 15 , fig. 5E–F.

Material examined

PACIFIC OCEAN • a colony composed of 6 stems 0.7–2.3 cm high, one of which bears a gonotheca; off New Caledonia, stn DW4768; 23°25′ S, 168°01′ E; 180–210 m; 27 Aug. 2016; KANACONO leg.; one stem was used for DNA extraction, DNA1362; voucher MHNG-INVE- 120796; barcode identifier MK 073090 ; MNHN-IK-2015-384 • a colony composed of 12 stems 0.4–2.3 cm high, one of which bears a gonotheca; same collecting data as for preceding; one stem was used for DNA extraction, DNA1363; voucher MHNG-INVE- 120797; 16 S sequence identical to MK 073090 ; MNHN-IK-2015-384 • a profuse colony with 0.5–2.3 cm high stems, some bearing gonothecae; off New Caledonia, stn DW4781; 22°57′ S, 167°47′ E; 295– 255 m; 29 Aug. 2016; KANACONO leg.; one stem was used for DNA extraction, DNA1364; voucher MHNG-INVE- 120798; MNHN-IK-2015-385 • a colony composed of 8 stems 2–2.3 cm high, three of which bear gonothecae; off New Caledonia, stn DW4742; 22°53′ S, 137°37′ E; 290–345 m; 23 Aug. 2016; KANACONO leg.; one stem was used for DNA extraction, DNA1365; voucher MHNG-INVE- 120799; MNHN-IK-2015-386 • a profuse colony on fascicled axis of unidentified hydroid, with stems up to 2.2 cm high, many of them bearing gonothecae; same collecting data as for preceding; one stem was used for DNA extraction, DNA1366; voucher MHNG-INVE- 120800; MNHN-IK-2015-386 • a profuse colony with stems up to 2 cm high, some bearing gonothecae; off New Caledonia, stn DW4782; 23°00′ S, 167°55′ E; 856– 845 m; 29 Aug. 2016; KANACONO leg.; MNHN-IK-2015-387 • a colony composed of ca 10 stems without gonothecae, 0.5–2 cm high; off New Caledonia, stn DW4741; 22°52′ S, 167°41′ E; 210 m; 23 Aug. 2016; KANACONO leg.; MNHN-IK-2015-388 • a colony composed of ca 10 stems without gonothecae, 1–2 cm high; off New Caledonia, stn DW4743; 22°52′ S, 167°34′ E; 380– 340 m; 23 Aug. 2016; KANACONO leg.; MNHN-IK-2015-389 .

Remarks

Unlike the holotype, some colonies in the present material are fertile. The gonothecae, of undetermined sex, are given off from within the hydrothecal lumina; broadly ovoid, ca 1420 µm long (and ca 1505 µm long including the spines, only one measured), laterally flattened (ca 1080 µm wide on widest side, only one measured), with 9–12 transverse ridges on both flattened sides, not meeting laterally, where two longitudinal, rounded, smooth ‘ridges’ are present. The small (ca 55 µm wide), rounded aperture is placed sub-apically, on a short, conical neck region, sometimes projecting outwards. The pair of apical ‘horns’ (distant of ca 1545 µm at their tips) is variably developed among colonies; in material MNHN-IK-2015-386, for example, they are almost indistinct, while an unequal development could be observed in sample MNHN-IK-2015-387.

In the light of the present findings, it could be noted that the fully-formed gonothecae of H. neocaledonica are similar to those of H. cornuta Galea, 2015 through both their size and shape (compare Fig. 7J to Galea 2015a: fig. 5D). However, these species can be readily distinguished on characters displayed by their trophosomes (compare Galea 2015a: figs 5E and 5A, respectively).

Unlike the type species of the genus, H. sibogae Billard, 1918 (see below), the present hydroid does not form rather tall colonies with fascicled stems, and its hydrothecae protrude for a long distance from the internodes. It comes close instead to Cyclonia gracilis Stechow, 1921 (now included in the synonymy of H. pusilla (Ritchie, 1910) , see Galea (2010: 20) and Galea & Ferry (2015: 236)), suggesting a possible future resurrection of the genus Cyclonia Stechow, 1921 to accommodate a group of species with short, simple, monosiphonic stems, long, tubular hydrothecae, and gonothecae arising from within the hydrothecae (occasionally also from the stolon, as in H. pusilla ).

Distribution

Only known from off New Caledonia ( Galea 2015a; present study).

Figures

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.