Sertularella aff. sinensis Jäderholm, 1896

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 : 39-40

Sertularella aff. sinensis Jäderholm, 1896

Figs 10E , 14 A–B

Sertularella sinensis – Vervoort & Watson, 2003: 177 , fig. 41D–H.

Sertularella aff. sinensis – Galea 2016: 30 , fig. 8P–S.

Material examined

PACIFIC OCEAN • a 4.7 × 3.8 cm colony, now broken into two pieces, bearing one gonotheca; off New Caledonia, stn DW4741; 22°52′ S, 167°41′ E; 210 m; 23 Aug. 2016; KANACONO leg.; MNHN- IK-2015-418 • a colony without gonothecae, 3.5× 3.3 cm; same collecting data as for preceding; a small fragment was used for DNA extraction, DNA 1386; voucher MHNG-INVE- 120847; MNHN- IK-2015-418 • a 2.2× 1.7 cm colony fragment bearing three gonothecae; same collecting data as for preceding; MNHN-IK-2015-418 • a 4× 1.6 cm colony with one gonotheca; same collecting data as for preceding; MNHN-IK-2015-418 • a fertile colony, with stems up to 4 cm high; off New Caledonia, stn DW4720; 22°50′ S, 167°11′ E; 374–400 m; 19 Aug. 2016; KANACONO leg.; MNHN-IK-2015-466 .

Remarks

The colonies are flabellate, with no definite main stem, as this branches many times, first branching occurring a short distance after its origin from stolon. The stem and side branches are strongly fascicled, tending gradually to monosiphonic distally. The hydrothecae are provided with 14–16 transverse ridges, while Galea (2016) reported hydrothecae with 19–21 ridges in material from New Caledonia examined so far. The gonothecae, ca 2790 µm long and 1570 µm wide (only one measured), display 6–8 broad transverse ridges; in one colony with three gonothecae, there are 4–6 apical spines surrounding the aperture; in two other colonies, each with but one gonotheca, seven and eight spines could be found, respectively, demonstrating that in the New Caledonian population, at least, their number is inconstant, and ranges from four to eight.

Galea (2016) pointed out morphological and morphometrical differences in materials studied by various authors, notably the condition of the stem, the number of hydrothecal ridges, and the size of gonothecae. The latter, in the present material, are the largest ever reported in this species, while Vervoort & Watson (2003) found 1720–1935 µm long and 1230–1280 µm wide gonothecae, although even smaller ones occurred in material studied by Hirohito (1995) (750–800 × 550–700 µm).

A more comprehensive study, based on materials of different origins, is needed to understand the variations reported so far in the literature.

Distribution

Sertularella sinensis , sensu stricto, occurs from China ( Jäderholm 1896) and Korea ( Park 2010) to the Sea of Okhotsk ( Naumov 1969). Additional material, possibly not conspecific, was recorded from New Caledonia ( Vervoort 1993; Galea 2016; present study), Tonga ( Galea 2016) and New Zealand ( Vervoort & Watson 2003).

Figures

Fig. 10.A. DynamenaoppositaGalea, sp.nov.,holotype colony, MNHN-IK-2015-470.—B.Hydrallmania clavaformis Galea, sp. nov., holotype colony, MNHN-IK-2015-404. — C. Sertularella leiocarpoides Vervoort, 1993, one colony from sample MNHN-IK-2015-420. — D. Sertularella novaecaledoniae Vervoort, 1993, colony from sample MNHN-IK-2015-424. — E. Sertularella aff. sinensis Jäderholm, 1896, one colony from sample MNHN-IK-2015-418. — F. Sertularella tronconica Galea, 2016, colony from sample MNHN-IK-2015-419. Scale bars: A–B, D–E = 1 cm; C = 2 cm; F = 5 mm.

Fig. 14. A–B. Sertularella aff. sinensis Jäderholm, 1896, gonotheca in lateral view (A), apical view of gonotheca showing spines and central aperture (B), both from sample MNHN-IK-2015-418. — C–E. Sertularella tronconica Galea, 2015, hydrotheca (C), apical view of aperture showing internal, submarginal cusps (D), portion of colony with male gonotheca (E). Scale bars: A, E = 1 mm; B = 300 µm; C = 200 µm; D = 100 µm.