Zyzzyzus robustus Petersen 1990

• Main Authors: Campos, Carlos J. A., Marques, Antonio C., Migotto, Alvaro E.
• Format: Other/Unknown Material
• Language: unknown
• Published: Zenodo 2007
• Subjects: Biodiversity; Taxonomy; Animalia; Cnidaria; Hydrozoa; Anthoathecata; Tubulariidae; Zyzzyzus; Zyzzyzus robustus; Greenland; Petersen; Cape Farewell; Qeqertat
• Online Access: https://doi.org/10.5281/zenodo.6244328; http://treatment.plazi.org/id/3F26D74DFFCD8930FF7268B1FD09FD14

Zyzzyzus robustus (Petersen, 1990) Table 4 Zyzzyzus robustus Petersen, 1990: 183, figs. 32–33.— Schuchert, 2001: 42 (footnote). Material examined. Preserved: Greenland: off Akuliaruseq (60°09’N. 44°10’W) (140 m), 12 Jul 1970, polyps on steep rocky slope (type with sponge fibers in the hydrorhiza); Cape Farewell Expedition st. 93; southwest Qeqertat (59°52.8`N, 43°31.5`W) (225 m) (no date), 10 polyps without gonophores, on encrusting bryozoans, ZMUC (without collection number). Description. Hydroids 7.3–29.0 mm in height, covered by thick, heavy perisarc, growing on rock, sponge, and encrusting bryozoans. Hydrorhiza swollen, with 1–3 large, strong, club-shaped processes, covered by stiff perisarc. Hydranth large, oblong; hydranth body 1.4–3.7 mm high, 0.7–3.5 mm in diameter at base. Oral tentacles filiform, ca. 40 in number, arranged in five whorls, adnate to hypostome around mouth, tentacles laterally flattened in cross section; most proximal whorl arising at right angles to hypostome, most distal whorl reaching no more than one-third of hypostomial length, 0.8– 0.14 mm long, 0.06–0.21 mm in diameter. Aboral tentacles filiform, 28–30 in number, tentacular bases contiguous to each other at base of hydranth body and in one whorl, tentacles laterally flattened in cross section, 0.8–3.8 mm long, 0.08–0.30 mm in diameter. Fertile hydranths with 21 blastostyles, ca. 1 mm in length, arranged in one imperfect or irregular whorl above aboral tentacles, each blastostyle with 8–14 spherical cryptomedusoid gonophores. Hydrocaulus trunk-like, bent from median to distal parts, cylindrical and covered by heavy, stiff perisarc at basal part, distal part of hydrocaulus narrowing, marked by end of stiff perisarc, surrounded by thinner perisarc. Transition between hydranth base and hydrocaulus smooth, without marked groove at region of perisarc secretion. Cnidome. Large stenoteles 10.2–13.5 x 8.2–12.2 Μm (11.2 ± 0.7 x 9.1 ± 0.8, n = 55); basitrichous isorhizae 5.3–6.8 x 1.8–2.5 Μm (6.2 ± 0.6 x 2.2 ± 0.3, n = 11) (aboral ...