Zygophylax medeae sp. nov.

(Figs 1E, 6, 7A)

urn:lsid:zoobank.org:act: 903897FE-7295-4144-8510-EADE9EB347FA

Material examined. BIOGEOCAL Stn CP 205, 22°40.61’– 22°41.07’S, 166°28.01’– 166°27.63’E (off SW of New Caledonia), 1350–1380 m, 08.04.1987: 27-mm-high stem, with gonothecae (all in slide) (Holotype, MNHN-IK-2019- 2045) .

Description. Stem polysiphonic, 27 mm high, with only a few hydrocladia and three hydrothecae left (Fig. 1E). Hydrocladial apophyses large (Figs 6A, D, 7A), much larger than hydrothecal apophyses, markedly separated from hydrocladia. Hydrocladia with a basal oblique ring (Fig. 6A, D). Basal part of first internode slightly swollen (Fig. 6A, D).

Hydrocladia monosiphonic (Fig. 1E), divided into very long internodes; hydrothecae relatively separated (Fig. 1E). Angle between apophyses and hydrocladia 80°.

Hydrothecal apophysis short, apparently without nematothecae. Distinct separation between hydrothecal apophysis and hydrothecal pedicel. Hydrothecae tubiform (Figs 6 B–D, 7A), more or less symmetrical, roughly straight, though slightly convex at adcauline side and slightly concave at abcauline side. Pedicel long (Figs 6 C–D, 7A), separated from hydrotheca by a slightly oblique diaphragm, marked by a thin ring of perisarc (Figs 6 C–D, 7A). Aperture circular, rim even with up to six renovations (Fig. 6C). Diameter of hydrothecae smoothly increasing to aperture.

Only a few nematothecae on accessory tubes present. Nematothecae elongate, cylindrical (Fig. 6 E–F).

Three gonothecae present (Fig. 1E). Gonotheca outline fusiform, but distal part with two opposing arms, each with a distal wide aperture (Figs 1E, 6F).

Measurements (in µm). Hydrothecae: length of abcauline wall 650–680, length adcauline wall 630–650, diameter at aperture 160–190, diameter at diaphragm 100, basal diameter 80–90, length of pedicel 480–500. Nematothecae: height 300–320, diameter at aperture 25, maximum diameter 40–50. Gonothecae: height 850–870, diameter at aperture c. 120, maximum diameter 350–380.

Remarks. The scarcity of material prevents me from determining the arrangement of the hydrothecae and the number of nematothecae on apophyses.

Zygophylax medeae sp. nov. is similar to Z. recta Jarvis, 1922 by the shape of the hydrotheca, although they are clearly distinguishable by the length of the pedicel, markedly much shorter in Z. recta . They also differ in the size of the hydrothecae, smaller in Z. recta (e.g. 150 µm in diameter at aperture), and nematothecae, shorter in Jarvis’s species (70–100 µm in height).

Etymology. The specific name medeae is a dedication to my daughter Medea Peña Sancho.