Zygophylax niobae, Peña Cantero, 2020

Peña Cantero, Álvaro L., 2020, On six new species of Zygophylax Quelch, 1885 (Cnidaria, Hydrozoa Zygophylacidae) from the New Calendonian region, Zootaxa 4822 (3), pp. 389-404 : 400

Zygophylax niobae sp. nov.

( Figs 1F , 7 B–C, 8)

urn:lsid:zoobank.org:act:353672F0-A2D0-4061-967A-081E319B74DC

Material examined. BIOCAL 1 Stn DW 36, 23°08.64’– 23°08.90’S, 167°10.99’– 167°11.29’E (S of New Caledonia), 650–680 m, 29.08.1985: a few stems up to 20 mm high (Holotype, MNHN-IK-2019-2046; paratype, MNHN-IK-2019-2047) .

Description. Stems up to 20 mm high, slightly polysiphonic except for their most distal part ( Fig. 1F ). Stems and branches in a distinct zigzag pattern ( Figs 1F , 7B , 8A ). Hydrocladia monosiphonic or slightly polysiphonic basally ( Fig. 1F ).

First-order branching alternate, in one plane, but with hydrocladia grouped in sub-opposite pairs ( Figs 1F , 7B , 8A ) and with two hydrothecae between successive pairs. Some hydrocladia becoming branches or lower-order stems and usually giving rise to a single hydrocladium, usually directed frontwards, at its first internode ( Fig. 1F ). However, some primary branches more developed, with extra secondary hydrocladia ( Fig. 1F ). Branching frequent (up to fourth-order branches present).

Separation between apophyses and hydrocladia usually marked only by a strong constriction of perisarc ( Figs 7B , 8 A–C). Angle between apophyses and hydrocladia 45–50°.

Hydrothecae on one side of stem, in two planes ( Fig. 8D ); angle more acute distally. Hydrotheca campanulate ( Figs 7 B–C, 8), bent adcaudally. Abcauline wall convex, adcauline one concave. Aperture circular, rim flared, usually with a few renovations. Pedicel short, cone-shaped ( Figs 7 B–C, 8), separated from hydrotheca by a thin ring of perisarc. Typically, with a relatively long intermediate internode between apophysis and pedicel ( Figs 7 B–C, 8); intermediate internode slightly swollen at distal end ( Figs 7 B–C, 8). Hydrothecal apophyses and intermediate internode separated by a strong constriction of perisarc ( Figs. 7C ).

Nematothecae not observed (they might be absent).

Gonothecae absent.

Measurements (in µm). Hydrothecae: length of adcauline wall 200–240, length of abcauline wall 250–350, diameter at aperture 100–120, diameter at diaphragm 50, length of pedicel 60–80, length of intermediate internode 160–250.

Remarks. Zygophylax niobae sp. nov. is similar to Z. bifurcata Billard, 1942 in the general shape of the hydrotheca. However, in Z. bifurcata the hydrotheca, more or less symmetrical, is straight, whereas in Z. niobae sp. nov. it is markedly bent. The hydrothecae are also distinctly larger in Z. bifurcata (155–185 µm in diameter at aperture, 320–365 µm in length from diaphragm to rim). In Z. bifurcata , according to Ramil & Vervoort (1992), who re-described the species, the pedicel is long, with wrinkled to indistinctly ringed portions. In Z. niobae sp. nov. the cone-shaped pedicel is short, and there is a long intermediate internode between hydrothecal apophysis and pedicel; occasionally, instead of a long intermediate internode there is a series of shorter ones, likely as a result of regeneration. The pedicel in Z. bifurcata is much longer (460–570 µm) than in Z. niobae sp. nov. (60–80 µm), even including the length of the intermediate internode (160–250 µm).

Etymology. The specific name niobae is a dedication to my daughter Níobe Peña Sancho.

Figures

FIGURE 1. Zygophylax dispersa sp. nov.: A, Colony shape, branching and coppiniae (arrows); B, detail of coppinia. Zygophylax encarnae sp. nov.: C, colony shape and branching. Zygophylax laertesi sp. nov.: D, colony shape, branching and coppinia (arrow). Zygophylax medeae sp. nov.: E, colony shape, branching and coppinia (arrow). Zygophylax niobae sp. nov.: F, colony shape and branching. Zygophylax pseudoabietinella sp. nov.: G, colony shape, branching and coppinia (circle); H, detail of coppinia. (All material from holotypes). Scale bar: 5 mm.

FIGURE 7. Zygophylax medeae sp. nov.: A, hydrocladial apophysis and axillary hydrotheca. Zygophylax niobae sp. nov.: B, stem fragment showing hydrocladial apophyses and axillary hydrotheca; C, hydrocladial hydrothecae. Zygophylax pseudoabietinella sp. nov.: D, distal stem fragment showing hydrocladial apophyses, axillary hydrotheca, and nematotheca; E, hydrocladial fragment showing shape and arrangement of hydrothecae. (All drawings from holotypes). Scale bar: 250 µm.

FIGURE 8. Zygophylax niobae sp. nov.: A–C, stem fragments showing hydrocladial apophyses and axillary hydrothecae; D–E, hydrocladial fragment showing shape and arrangement of hydrothecae; F–H, hydrothecae. (All photographs from the holotype). Scale bar: 200 µm (A–E), 100 µm (F–H).