Zancleopsis sp.

Maggioni, Davide, Schuchert, Peter, Arrigoni, Roberto, Hoeksema, Bert W., Huang, Danwei, Strona, Giovanni, Seveso, Davide, Berumen, Michael L., Montalbetti, Enrico, Collins, Richard, Galli, Paolo & Montano, Simone, 2021, Integrative systematics illuminates the relationships in two sponge-associated hydrozoan families (Capitata: Sphaerocorynidae and Zancleopsidae), Contributions to Zoology 90, pp. 487-525 : 514

Zancleopsis sp.

Examined material: Sample SN 006, Singapore, 28/11/2017, polyps in ethanol and formalin. – Sample SN 117, Singapore, 30/11/2017, polyps in ethanol and formalin. – Sample SN 120, Singapore, 30/11/2017, polyps in ethanol and formalin. – Sample SN 143, Singapore, 01/12/2017, polyps in ethanol and formalin .

Description: Polyp. Colonies monomorphic, living in association with sponges ( figs. 9 A-C). Hydrorhiza tubular and covered by a thin perisarc, embedded by the sponge host. Pedicels short and completely embedded in the sponge host, unbranched, covered by a thin perisarc. Hydranth cylindrical to slightly pyriform, up to 0.75 mm long, with variable diameter (80–150 Μm) ( figs. 9 A-D). Hypostome proboscis-like. Tentacles organised in two alternating whorls of 4–5 tentacles ( figs. 9 C-D). Each tentacle with terminal and sub-terminal capitula (diameter: 80–100 Μm in the distal whorl; 40–70 Μm in the proximal whorl) ( fig. 9E ). Tentacles 350– 380 Μm long in the distal whorl, shorter in the proximal whorl (about 250 Μm). Nematocyst clusters about 50–80 Μm distant from one other. Living hydranths transparent, with white mouths ( figs. 9 A-C). Desmonemes, microbasic euryteles, small and large stenoteles ( figs. 9 F-H) occurring simultaneously and concentrated in the capitula, as well as scattered in the hydrorhiza; microbasic euryteles also scattered in the hydranth.

Polyp cnidome. i) Desmonemes (undischarged: 7–8 × 4–5 Μm; discharged capsule: 6 × 4 Μm). ii) Microbasic euryteles (undischarged: 13–14 × 4–6 Μm; discharged capsule: 12 × 5 Μm; shaft: 20 Μm). iii) Large stenoteles (undischarged: 20–23 × 13–14 Μm; discharged capsule: 19 × 13 Μm). iv) Small stenoteles (undischarged: 9–10 × 6–7 Μm; discharged capsule: 9 × 6 Μm).

Distribution: Only known from the Indo-West Pacific ( Singapore).

Remarks: This species has polyps that are apparently identical to those of Z. dichotoma in both general morphology and cnidome, and was separated from the latter based on molecular data alone, nevertheless showing high genetic divergence. Since the adult medusa is unknown, it is currently not possible to identify these colonies to the species level using morphology alone. Because it could additionally also belong to an already named medusa, we prefer here not to give it a new species name, also because all the other Zancleopsis species not sampled in this work have their type localities in the Western Pacific, namely in the Banda Sea, Bismarck Sea, South China Sea, and Japan ( Uchida, 1927; Kramp, 1928; Bouillon, 1978, 1985; Wang et al., 2016).

Figures

FIGURE 9 Zancleopsis sp. A-C) Polyps from Singapore.D) Close-up of a polyp. E) Tentacle with terminal and subterminal capitula.F) Large stenoteles (ls), small stenoteles (ss), and desmonemes (d). G) undischarged and H) discharged microbasic eurytele.Scale bars: A-D) 0.2 mm; E) 20 Μm; F-H) 5 Μm.