Zygophylax cervicornis ( Nutting, 1905 )

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 : 9-12

Zygophylax cervicornis ( Nutting, 1905)

( Figs 4 , 5 , 25 ; Tables 3 , 8 )

Lictorella cervicornis Nutting, 1905: 946 , pl. 4 fig. 1, pl. 10 figs 5–9.

Zygophylax cervicornis – Schuchert, 2015: 332, fig. 7 (cum syn.).

Material examined. MNHN-IK-2015-3065, KANADEEP 2 Stn. CP 5108: a flabellate colony, 9 × 9 cm, bearing four coppiniae (largest 6 × 4 mm); GenBank: OP724366 .— MNHN-IK-2019-2147, KANACONO Stn. DW 4698: a colony of originally undeterminable size, now broken into four pieces, one of them (5 cm high) bearing a fullyformed coppinia (10 × 4 mm), and another one (4.5 cm high) with an incipient coppinia (6 × 1.5 mm); GenBank: OP724367 .

Description. Colonies erect, flabellate, largest 9 × 9 cm, relatively stiff, arising from dense stolonal network firmly adhering to various substrates; stem and branches (up to the 3 rd order) coplanar, fascicled for most of their length; stem 1.5 mm wide basally; auxiliary tubes straight, running parallel to the main tube, communicating through lateral, rounded pores in the perisarc, bearing scattered, long, club-shaped nematothecae; main tube straight, not regularly divided into internodes, but bearing occasional transverse constrictions of the perisarc, composed of successive modules, each comprising proximally a long apophysis (together with its axillary hydrotheca atop its own apophysis) supporting a cladium, two alternating, slightly shorter apophyses above, each supporting a hydrotheca, and a distal apophysis (with its axillar hydrotheca) supporting another cladium, given off on side opposite to its proximal counterpart; all apophyses coplanar. Cladia straight, up to 14 mm long, either monosiphonic or lightly fascicled proximally, occasionally becoming elongate, polysiphonic, and eventually transform into lower-order cladia-bearing branches; division into internodes irregular, through distinct, transverse nodes, each comprising 1–5 hydrothecal apophyses; up to 41 apophyses per cladium, alternate, coplanar, comparatively shorter than their cauline counterparts. Hydrothecae pedicellate; pedicels well-developed, either smooth-walled or with generally 1, occasionally 2, rarely 3 and exceptionally 4 distinct annuli proximally; pedicels gently flaring from base to distal end, and there merging smoothly with the hydrothecal wall, demarcation internal, though a transversely- to obliquelyset, relatively thin diaphragm, bearing centrally a rounded foramen (with slightly upturned edge) for the passage of the hydranth; adaxial wall of theca slightly sigmoid, convex in proximal half, concave in distal half; abaxial wall straight for ca. 2/3 of its proximal length, and slightly concave distally; distal part of hydrotheca cylindrical, proximal part tapering gently; perisarc thin, smooth; aperture transversely-set, circular, slightly everted, rim even, with up to 9 renovations. Nematothecae occurring indifferently singly or in pairs, on the apophyses supporting both the cladia and hydrothecae, occasionally (apparently only) singly on the apophyses of axillar hydrothecae; short, barrelshaped, tapering both above and below, aperture small, circular. Coppinia arising from both the stem and branches, composed of closely-set, though individual gonothecae, among which are given off protective tubuli that branch extensively and dichotomously above the gonothecae, branchlets often anastomosing and bearing numerous long, digitiform nematothecae; gonothecae inverted-conical, borne on indistinct pedicels, distally provided with a couple of upwardly-directed funnels, each bearing terminally a large, circular aperture.

Remarks. The New Zealand record by Vervoort & Watson (2003: 72) likely belongs to another species, due to the presence of a couple of nematothecae on the hydrothecal pedicels; in addition, their material was sterile and, hence, difficult to identify.

Distribution. Hawaii ( Nutting 1905, as L. cervicornis ), Japan ( Schuchert 2015), New Caledonia (present study).

Figures

FIGURE 4. Zygophylax cervicornis (Nutting, 1905) (part). A, B. Apical parts of two colonies. C–J. Cauline (C, D), axillar (E, F) and cladial (G–J) hydrothecae. From samples MNHN-IK-2015-3065 (A, C, E, G, H) and -2019-2147 (B, D, F, I, J). Scale bars: C–J = 300 µm; A, B = 1 mm.

FIGURE 5. Zygophylax cervicornis (Nutting, 1905) (continued). A. Nematothecae from the auxiliary tubes of the stem. B– D. Nematothecae associated to the cauline (B), cladial (C) and axillar (D) hydrothecae. E, F. Nematophorous tubules. G, H. Gonothecae. From samples MNHN-IK-2015-3065 (C, E, G) and -2019-2147 (A, B, D, F, H). Scale bars: A–D = 100 µm; E–H = 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.