Zyzzyzus floridanus Petersen, 1990

Campos, Carlos J. A., Marques, Antonio C. & Migotto, Alvaro E., 2007, A taxonomic revision of the genus Zyzzyzus Stechow, 1921 (Cnidaria: Hydrozoa: Tubulariidae), Zootaxa 1627, pp. 1-22 : 5-7

Zyzzyzus floridanus Petersen, 1990

Table 2

Zyzzyzus floridanus Petersen, 1990: 178 , fig. 29.

Material examined. Preserved: United States of America: Florida, Miami (ca. 25°45’N, 80°15’W), west of Long Reef (2 m), 27 Jan 1965, coll. C. Nielsen, one hydroid, with one fully developed gonophore (type); one hydroid, without gonophores; several hydroids, without gonophores; embedded in the sponge Callyspongia vaginalis (paratypes), ZMUC (without collection number).

Description. Hydroids 2.2–4.4 mm high, with hydrocaulus stiffly embedded in sponge ( Callyspongia vaginalis ). Hydrorhiza with up to four rounded bulbs. Hydranth vasiform; hydranth body 0.5–0.9 mm high, 0.3–0.5 mm in maximum diameter. Oral tentacles short, filiform, 8–15 in number, arranged in two close whorls, with both whorls adnate to hypostome around mouth, 0.15–0.28 mm long, 0.03–0.05 mm in maximum diameter. Aboral tentacles long, filiform, 15–20 in number, evenly spaced at base of hydranth body in one whorl, space between adjacent tentacular bases equal to diameter of tentacles; tentacles ovate in cross section near base, circular in cross section at distal free part, 0.7–2.1 mm long, 0.03–0.08 mm in maximum diameter. Fertile hydranths with short blastostyles in one whorl above aboral tentacles, each blastostyle with cryptomedusoid gonophores. Only female gonophores observed. Developed female gonophores oval, widening distally, as long as hydranth, reaching tips of oral tentacles, distal end smooth around orifice, 0.47–0.50 mm long, 0.28–0.30 mm in maximum diameter. Gonophores when completely developed containing one actinula. Hydrocaulus flexible, sometimes twisted or bent in several directions, covered by thin perisarc at median and distal parts, basal part of hydrocaulus embedded in sponge with thickened perisarc; hydrocaulus widening proximally, distal part of hydrocaulus cylindrical, basal and median parts ovate in cross section. Perisarc secreted at region above circular groove, between hydrocaulus and hydranth base; preserved material with hydrocaulus having folded perisarc. Coenosarc of hydrocaulus with 8–11 basal longitudinal canals, anastomosed in 4–6 distal longitudinal canals.

Cnidome. Large stenoteles 11.1 x 10.0 Μm (n = 1); small stenoteles 5.3–6.0 x 4.0–5.3 Μm (5.6 ± 0.17 x 4.4 ± 0.35, n = 16); basitrichous isorhizae 5.3–6.1 x 2.0–2.5 Μm (5.5 ± 0.26 x 2.2 ± 0.13, n = 10); heterotrichous microbasic euryteles 7.4–8.4 x 4.2–5.0 Μm (7.8 ± 0.31 x 4.6 ± 0.26, n = 16); desmonemes 3.1–3.6 x 2.1– 3.1 Μm (3.4 ± 0.21 x 2.6 ± 0.25, n = 11) (hydranth).

Additional data. Petersen (1990: 178–179) described “about 14 tentacles” in the actinula of the type material and concentrations of nematocysts “at tip and along aboral side” in the oral tentacles and “along aboral surface” in the aboral tentacles [pseudofiliform type defined by Prévot (1959)]. Male gonophores are unknown.

Colour. Transparent white in alcohol-preserved material ( Petersen 1990, our observations).

Type. One hydroid removed from sponge, up to 2.3 mm high, with 15 short filiform oral tentacles and 16 filiform aboral tentacles. Hydranth supporting one completely developed gonophore containing one actinula and 5 short incompletely developed blastostyles, arising distal to aboral tentacles in a circular whorl, ZMUC (without collection number) ( Petersen 1990: 179).

Additional material. Several hydroids without gonophores, embedded in sponge ( C. vaginalis ), ZMUC (without collection number).

x ± SD (in Μm) Range (in Μm) n

Hydrorhiza

Number of processes 4 - 1 Length 1247 ± 27 1224–1276 3 Diameter 357 ± 82 274–466 6 Hydrocaulus

Length 1494 ± 612 469–2185 6 Proximal diameter 375 ± 114 250–586 15 Median diameter 283 ± 98 147–461 14 Distal diameter 273 ± 58 177–353 20 Hydranth

Total length 651 ± 116 504–901 12 Length from aboral tentacle bases to hypostomial tip 467 ± 92 373–648 10 Diameter at base 425 ± 68 320–547 16 Oral tentacles

Number 10 ± 3 8–15 6 Length 219 ± 50 149–284 11 Diameter 39 ± 5 29–49 21 Aboral tentacles

Number 17 ± 2 15–20 8 Length 1413 ± 420 685–2103 24 Diameter 59 ± 12 31–77 28 Gonosome

Total number 1 - 1 Male gonophore

Number - - - Length - - - Diameter - - - Female gonophore

Number 1 - 1 Length 479 ± 16 466–497 3 Diameter 282 ± 6 276–288 3 Blastostyles

Number 1 - 1 Length - - - Diameter - - -

Remarks. The diagnostic characters of Z. floridanus are the barrel-shaped hydranth, the two whorls of oral tentacles, and the smooth surface of the female gonophore around orifice.

The study of the material above corroborated most details of the general description by Petersen (1990). However, our observations do not coincide with his descriptions of the hydranth ("slimly vasiform") and the aboral tentacles (“rectangular cross-section”) ( Petersen 1990: 178). Although no morphometric data were given by Petersen (1990), the increasing number of oral tentacles might cause a projection enlarging the hypostome, changing the whole morphology of the hydranth. As for aboral tentacles being “rectangular in cross-section," there are no other accounts of this kind of tentacular morphology among tubulariid species. Instead, we adopted the general nomenclature and definitions following Prévot (1959).

Petersen (1990: 156) observed in several tubulariids the existence of a “reversed pear-shaped neck region, which in Zyzzyzus is very prolonged and constitutes about half of the hydrocaulus.” From our observations, Z. robustus is the only species ever assigned to the genus with a narrowed distal hydrocaulus, clearly distinguishable by perisarc thickness. Therefore, we did not establish any morphological differentiation between distal and median regions in the hydrocaulus of Z. floridanus [which Petersen (1990) considered as having a “ringshaped swelling”] or in any other species of the genus, and we discard the idea of distinguishing a “neck region" in the hydrocaulus of species of Zyzzyzus .

We (and Petersen, 1990) observed only female gonophores, and male gonophores of the species are unknown. Consequently, the nature of the blastostyles (whether mono- or dioecious) has not yet been determined for this species.

Distribution. Northwestern Atlantic: shallow-waters off west of long reef, Miami, Florida, United States of America (ca. 25°45’N, 80°15’W) ( Petersen 1990).

Ecology. Substratum. The thickness of the perisarc on hydrorhizal processes suggests that the species is strongly embedded on volcano-like projections of the sponge Callyspongia vaginalis .

Seasonality. January (one actinula present in type material) ( Petersen 1990).

Depth. 2 m at low tide ( Petersen 1990).