Zygophylax levinseni, (SAEMUNDSSON, 1911)

Gu, Zhangjie, Ruthensteiner, Bernhard, Moura, Carlos J., Liu, Lihua, Zhang, Rui & Song, Xikun, 2022, Systematic affinities of Zygophylacidae (Cnidaria: Hydrozoa: Macrocolonia) with descriptions of 15 deep-sea species, Zoological Journal of the Linnean Society (Zool. J. Linn. Soc.) 196, pp. 52-87 : 68

ZYGOPHYLAX LEVINSENI ( SAEMUNDSSON, 1911)

( FIG. 11 )

Zygophylax levinseni: Vervoort, 2006: 240–242 , fig. 16 (synonymy).

Type locality: Near the Vestmannaeyjar Archipelago, Iceland ; 510 m.

Specimens examined: Five colonies from the Gulf of Cadiz, two fertile; see details in Supporting Information, Table S1 .

Molecular sequences: 16S rRNA ( Moura et al., 2008, 2012); 18S rRNA and 28S rRNA genes (this study); see sequence details in Supporting Information, Table S3 .

Measurements: See details in Supporting Information, Table S2 .

Description: Trophosome. Colonies erect, up to 4.5 cm in height ( Fig. 11A ). Hydrocaulus straight, polysiphonic, unsegmented, branching. Hydrocladia coplanar, dichotomously branched, straight, monosiphonic ( Figs 11A, B ), with irregular nodes ( Fig. 11E ), forming angles of 30°–60° with the hydrocaulus ( Fig. 11A ), axillary hydrothecae present at branching points ( Fig. 11E ). Hydrothecae arranged alternately in two planes forming angles of 30°–60° ( Fig. 11B ); borne on moderately long pedicels, tubular, distal part straight or slightly curved, one or two oblique diaphragms basally ( Fig. 11D ), margin slightly everted, with one to three renovations ( Fig. 11D–F ). One nematotheca present on apophyses of hydrocladia ( Fig. 11F, H ).

Gonosome: Gonothecae clustering into coppiniae encircling the hydrocaulus ( Fig. 11C ), with abundant protective tubes, one nematotheca observed on the base of one protective tube ( Fig. 11G, I ). Gonothecae free from one another, elliptical, tapering basally, apices with two lateral, curved tubes ( Fig. 11C, G ).

Distribution: Gulf of Cadiz ( Moura et al., 2008; this study); south of Iceland ( Saemundsson, 1911); the Azores region ( Leloup, 1940); near the coast of Rabat, Morocco ( Ramil & Vervoort, 1992); one tropical Atlantic locality, south of Cape Verde Islands ( Vervoort, 2006); Madeira ( Moura et al., 2012).

Remarks: Zygophylax tottoni Rees & Vervoort, 1987 resembles Z. leviseni by the hydrothecal morphology, but Z. leviseni has comparatively more numerous and smaller nematothecae; see details in Supporting Information, Table S2.

Figures

Figure 11. Zygophylax levinseni (Saemundsson, 1911). A, three colonies; B, hydrothecal arrangement along a hydrocladium; C, a coppinia; D, two hydrothecal diaphragms (arrows); E, axillary hydrotheca and a node (arrow); F, two hydrothecae and two clearly identifiable nematothecae (arrows); G, a gonotheca and one nematotheca on an accessory tube (arrow); H, magnification of nematothecae on apophysis of hydrocladia (in F, lower arrow); I, magnification of nematothecae on the accessory tubes (in G). From samples: A–I: ZSM 20220297, Gulf of Cadiz. A–D, light microscope images; E–I, SEM images. Scale bars: A = 1 cm; B, C = 1 mm; D–G = 200 µm; H, I = 50 µm.