Zygophylax pseudosibogae Gu, Moura & Song, 2022

Galea, Horia R., Maggioni, Davide & Galli, Paolo, 2022, On some species of Zygophylax Quelch, 1885 (Cnidaria: Hydrozoa: Zygophylacidae) from off New Caledonia, Zootaxa 5214 (1), pp. 1-46 : 30-32

Zygophylax pseudosibogae Gu, Moura & Song, 2022

( Figs 17 , 18 , 25 ; Tables 6 , 8 )

Zygophylax pseudosibogae Gu, Moura & Song (in Gu et al.), 2022: 75, figs 13C–D, 14C, 17.

Zygophylax sibogae – Ralph, 1958: 311, fig. 2E–I.— Millard, 1964: 21, fig. 5G–H.— Millard, 1975: 198, fig. 65A–C.—? Hirohito, 1983: 32, fig. 12.—Altuna Prados & Álvarez-Claudio, 1994: 10, figs 5, 6.— p.p. Vervoort & Watson, 2003: 80, fig. 13G–K (not 14A, B = Z. sibogae ).— Vervoort, 2006: 247, fig. 19B, C.—? Schuchert, 2015: 337, fig. 10.

Material examined. MNHN-IK-2019-2142, KANADEEP 2 Stn. CP 5095: two infertile colonies 5.5 × 5.5 cm and 6.5 × 5.5 cm; GenBank: OP724383 .—MNHN-IK-2015-2933, KANADEEP Stn. DW 4962: a colony composed of three stems, tallest 3.5 cm high, all bearing a coppinia (one of them was removed and dissected) .

Description. Colonies detached from their substrates above origin from hydrorhiza; erect, flabellate, reaching 6.5 × 5.5 cm (height × width), irregularly branched (up to the 3 rd order); stems and branches fascicled for most of their length, the former ca. 1 mm wide basally. Main cauline tube slightly geniculate, usually unsegmented, composed of a succession of modules comprising a proximal apophysis (and its axillar hydrotheca atop its own apophysis) supporting a cladium, two alternate apophyses above, each bearing hydrotheca, and a distal apophysis (together with its axillar hydrotheca mounted on its apophysis) supporting another cladium, given off on the opposite side to the preceding counterpart; apophyses shifted on to the “anterior” side of the stem, distant from one another, those supporting the cladia comparatively longer than those bearing the hydrothecae; usually a “fronto”- adaxial nematotheca (exceptionally twins) per cladial apophysis, sometimes a pair (a theca per side); hydrothecal apophyses with single, adaxial nematothecae; all apophyses ending distally in transverse node. Auxiliary tubes of the stem slightly tortuous, running parallel to the main tube, occasionally branching and anastomosing, bearing numerous tubular nematothecae (often renovated) of varied lengths. Cladia to 8 mm long, almost straight, either undivided or irregularly divided by transverse nodes into internodes bearing 1–3 apophyses, each supporting a hydrotheca, and bearing adaxially a single nematotheca, the latter simple or renovated; up to 12 distant hydrothecae per hydrocladium; hydrothecal apophyses of comparable length to their cauline counterparts, alternate, equally shifted on to the “anterior” side of the colony; developing cladia gain increasing fasciculation and length, and transform themselves into branches that can rebranch again. Hydrothecae biseriate, alternate, the two rows forming a very acute angle between them; pedicellate; pedicels of either the same length or longer than the hydrothecae themselves; occasionally one (exceptionally two) nematothecae (either simple or renovated) per pedicel, generally in middle part; pedicels smooth-walled, gradually widening and merging imperceptibly with their hydrothecae, demarcation internal, as transverse septa, with raised, V-shaped edge on abaxial side; hydrotheca relatively long, tubular, distinctly curved adaxially in middle, occasionally with conspicuous internal notch at the site of curvature; walls finely and densely striated transversely; apertures set at right angle to the main axis of hydrotheca, often renovated several times, margin everted, rim even, rounded in apical view; on stem, thecal apertures facing obliquely upwards on both sides; on cladia, apertures of the hydrothecae facing either obliquely upwards (row close to the stem) or outwards (row away from the stem); finally, all hydrothecal apertures, regardless their belonging to the stem or cladia, facing towards the “posterior” side of the colony. Nematothecae tubular, of varied length, often renovated (renovations marked by transverse constrictions), slightly tapering distally towards a small, circular, transversely-set aperture. Coppinia borne on a side branch; small (ca. 2 mm wide), globular, composed of 6–7 unfused gonothecae and nematophorous tubules, all arising from the accessory tubes of the branch; gonothecae vasiform, thick-walled, finely and densely striated transversely, tapering basally, distally with 2–3 lateral, curved projections, each bearing terminally a rounded aperture; sex female, about 7–8 large, ovoid oocytes per gonotheca; nematophorous tubules protruding from amidst the gonothecae, simple proximally for a length slightly surpassing the height of the gonothecae themselves, then dichotomously-branched several times, branchlets often anastomosing and forming a thick canopy over the gonothecae; nematothecae digitiform, tapering abruptly apically, where they are provided with a small, circular aperture.

Remarks. Several records of Z. sibogae Billard, 1918 are likely attributable to the present species. Indeed, the hydrothecae depicted by a number of authors (see the proposed synonymy above) do not show the distinctive bent of the adaxial wall (compare their illustrations to Fig. 21B herein).

Distribution. Portugal ( Gu et al. 2022), Gulf of Biscay (Altuna Prados & Álvarez-Claudio 1994, as Z. sibogae ), Canary Islands ( Vervoort 2006, as Z. sibogae ), South Africa ( Millard 1964, 1975, as Z. sibogae ),? Japan ( Hirohito 1983; Schuchert 2015; both as Z. sibogae ), New Zealand ( Ralph 1958; p.p. Vervoort & Watson 2003; both as Z. sibogae ), New Caledonia (present study).

Figures

FIGURE 17. Zygophylax pseudosibogae Gu, Moura & Song, 2022 (part). A. Apical part of a colony. B–E. Nematothecate from the auxiliary tubes of the stem. F–K. Cauline (F, G), axillar (H) and cladial (I–K) hydrothecae. From samples MNHN-IK-2015- 2933 (J, K) and -2019-2142 (A–I). Scale bars: B–E = 100 µm; F–K = 300 µm; A = 1 mm.

FIGURE 18. Zygophylax pseudosibogae Gu, Moura & Song, 2022 (continued). A–D. Simple or renovated nematothecae associated to a cladial apophysis and (occasionally to) a hydrothecal pedicel (A), and to the apophyses supporting cladial hydrothecae (B–D). E, F. Diaphragm in frontal (E) and (F) lateral aspects. G. Nematophorous ramulus; note basal nematothecae. H–J. Two gonothecae, one with two (H), the other with three (I, J) apertures, in lateral (H, I) and apical (J) views. From samples MNHN-IK-2015-2933 (G–J) and -2019-2142 (A–F). Scale bars: A–F = 100 µm; G–J = 500 µm.

FIGURE 21. Zygophylax sibogae Billard, 1918 (continued). A. Nematotheca associated to an apophysis supporting a cladial hydrotheca. B, C. Same hydrotheca in lateral (B) and dorsal (C) aspects. D. Nematothecate ramulus. E, F. Two gonothecae, one with two apertures (seen laterally, E), the other with three apertures (seen apically, F). All from sample MNHN-IK-2019-2136. Scale bars: A–C = 100 µm; D–F = 500 µm.

FIGURE 25. Phylogenetic hypothesis for the Zygophylaciidae based on the 16S rRNA gene. Numbers at nodes refer to support values of the maximum likelihood, Bayesian inference and maximum parsimony analyses, respectively, and are shown only when> 70 and 0.7. Sequences generated in this study are followed by voucher numbers.