Zancleopsis cabela ( Maggioni et al., 2017 ) Maggioni & Schuchert & Arrigoni & Hoeksema & Huang & Strona & Seveso & Berumen & Montalbetti & Collins & Galli & Montano, 2021

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 : 511-514

Zancleopsis cabela ( Maggioni et al., 2017) comb. nov.

Zancleopsis dichotoma . Bigelow, 1938: 102, figs 1–2 ; Schuchert & Collins, 2021 (large form): 272, fig. 23.

Astrocoryne cabela Maggioni et al., 2017: 737 , figs. 2–4 .

Examined material: Sample MA 16053, Maldives, 08/02/2016, polyps in ethanol and formalin (MSNM-Coe-341) and young medusae in formalin (MSNM-Coe-342). – Sample MA 16052, Maldives, 08/02/2016, polyps in ethanol and formalin. – Sample MA 1016013, Maldives, 12/10/2016, polyps in ethanol and formalin. – Sample KA 175, Saudi Arabia 17/12/2015, polyps in ethanol. –Sample BFLA4408 , off Florida, 26/05/2020, part of medusa in ethanol and in situ photos. – Sample BFLA4467 , off Florida, 17/06/2020, medusa in formalin (UF-014072), ethanol and in situ photos .

Description: Polyp. Colonies monomorphic, living in association with sponges ( figs. 8 A-C). Hydrorhiza tubular, covered by moderately thick and slightly wrinkled perisarc, embedded by the sponge host. Pedicels short to moderately long (up to 580 Μm), unbranched, covered by a smooth, thin, cup-shaped or elongated perisarc. Hydranth pyriform or slightly pyriform, up to 0.8 mm long, with variable diameter (up to 250 Μm). Hypostome proboscis-like, contractile. Up to 10 tentacles (range 8–10) arranged in one or two close whorls in the broadest part of the polyp. Each tentacle with terminal and sub-terminal capitula (diameter: 50–110 Μm in the distal whorl; 25–45 Μm in the proximal whorl) ( fig. 8D ). Tentacles up to 550 Μm long in the distal whorl, shorter in the proximal whorl (up to 320 Μm) when present. Nematocyst clusters about 100 Μm distant from one other, closer when tentacles are contracted. Up to 11 medusa buds at different stages of maturation develop among tentacles, singly or in couple on blastostyles ( fig. 8E ). Living hydranths transparent, with white mouths and whitish or light orange gastric cavities. Desmonemes, microbasic euryteles, small, large and medium-sized stenoteles ( figs. 8F, G ) occurring simultaneously in the terminal and proximal capitula, and in the hydrorhiza, rare in the hydranth.

Newly liberated medusa. Newly liberated medusa hemispherical, up to 500 Μm wide and high, with nematocysts scattered on the exumbrella. Manubrium cylindrical, up to 200 Μm long and 110 wide at the base, spanning from 1/3 to 1/2 of the bell height, distally provided with a circular mouth. Four radial canals ending in four bulbs with a diameter of up to 70 Μm, and a circular canal. Bulbs and circular canals containing nematocysts. At release medusae with no tentacles, but with bulbs showing swellings filled with nematocysts. Two opposite tentacles after two days from release. Tentacles up to 300 Μm long, with terminal spherical nematocyst-rich capitula with a diameter of up to 85 Μm. Ocelli absent at release. Microbasic mastigophores and rarely microbasic euryteles scattered on the exumbrella, medium-sized stenoteles in the circular canal, medium-sized stenoteles and desmonemes in the bulb swellings and in the terminal capitula of tentacles.

Polyp and newly liberated medusa cnidome. i) Desmonemes (undischarged: 7–9 × 4–5 Μm; discharged capsule: 6–8 × 4–5 Μm). ii) Microbasic euryteles (undischarged: 13–15 × 5–6 Μm; discharged capsule: 10–12 × 4–5 Μm; shaft: 9–11 Μm). iii) Large stenoteles (undischarged: 18–21 × 13–17 Μm; discharged capsule: 15–18 × 11–15 Μm). iv) Medium-sized stenoteles (undischarged:9–10 × 6–7 Μm;discharged capsule: 8–9 × 5 Μm). v) Small stenoteles (undischarged: 5–6 × 4–5 Μm; discharged capsule: 5 × 4–5 Μm). vi) Microbasic mastigophores (undischarged: 6–7 × 5–7 Μm; discharged capsule: 5 × 5 Μm; shaft: 5 Μm).

Adult medusa (from Schuchert & Collins, 2021, Z. dichotoma large form). Similar but much larger than Z. dichotoma (= small form), height 8 to 15 mm and 5 mm diameter, apical process larger reaching 1/2 of total height, tip of apical process whitish, more and larger vertical gonad folds, approximately up to 15, grouped in 2–3 folds adradial, brownish, oocytes yellow, tentacle bulbs with intense yellow colour, shorter tentacle pair longer than in Z. dichotoma ( figs. 8 H-K).

Distribution: Atlantic Ocean ( Bermuda, Florida), and Red Sea and Indo-West Pacific ( Saudi Arabia; Maldives).

Remarks:The polyp stage of this species was previously identified as A. cabela , but genetic data allowed us to link it to the large morph of Z. dichotoma described by Schuchert & Collins (2021), further confirming the synonymisation of Astrocoryne with Zancleopsis . The main differences to Z. dichotoma are a larger adult medusa and larger polyps with tentacles less regularly organised. Kramp (1968) suspected that Z. dichotoma and Zancleopsis tentaculata Kramp, 1928 could be conspecific. Zancleopsis tentaculata (type locality: Banda Sea, Indonesia) generally shows a larger size and the short tentacles are longer than in Z. dichotoma , something shared with Z. cabela . However, given the uncertainties in the morphological identification of Z. tentaculata we prefer to ascribe these specimens to Z. cabela , because genetic data of the type material of A. cabela were included in the analyses.

Figures

FIGURE 1 Phylogenetic hypotheses for the Sphaerocorynidae and Zancleopsidae.A) Sampling localities.B) Phylogenetic reconstruction of the Capitata based on the concatenated multi-locus dataset, with numbers at nodes representing ML bootstrap values, Bayesian posterior probabilities, and MP bootstrap values, respectively; asterisks denote maximal support for all analyses, whereas dashes denote absence of the node in the analysis; samples corresponding to medusa stages are highlighted in grey. C) Species tree of the Sphaerocorynidae and Zancleopsidae, with numbers at nodes representing Bayesian posterior probabilities.

FIGURE 2 Sphaerocoryne bedoti. Polyps from A, B) Maldives and C) Sint Eustatius. D) Tentacles organisation. E) Close-up of a hydranth showing the typical colouration.F) Hypostome, with a nematocyst band (arrowhead).G) Living polyp detached from the host and trying to ingest a portion of the host sponge.H) Capitulum with a central inclusion.I) Polyp with medusa buds organised in clusters.J) Close-up of a polyps with medusa buds clusters arising from the red band area. K) Polyp with medusa buds showing reproductive exhaustion.L) Newly released medusa.M) Desmonemes (d) and small stenoteles (ss) from the polyp. N) Large stenoteles (ls) and small stenoteles (ss) from the polyp. O) Heteroneme from the polyp.Scale bars: A, B) 0.5 mm; C-G, I-K) 0.2 mm; H, L) 25 Μm; M-O) 5 Μm.

FIGURE 3 Kudacoryne diaphana. Polyps from A, B) Red Sea and C, D) Maldives.E) Hypostome. F) Capitulum.G) Polyps with medusa buds a few hours before release. H) Newly released medusa. I) Large stenoteles (ls), small stenoteles (ss), and desmonemes (d) from the polyp stage.J) Macrobasic mastigophore from the polyp stage.K) Small stenoteles (ss) and microbasic mastigophores (mi) from the newly released medusa.Scale bars: A-D,G) 0.2 mm; E, H) 50 µm; F) 20 µm; I-K) 5 µm.

FIGURE 4 Euphysilla pyramidata. A, B, C) Polyps from the Maldives.D) Close-up of a hydranth showing the typical colouration. E) Hypostome with nematocysts (arrowhead). F) Longitudinal organisation of tentacles.G) Polyps with medusa buds. H) Large stenoteles (ls), small stenoteles (ss), I) desmonemes, and J) heteronemes from the polyp.K, L) Medusae with medusa buds.M) Detail of a bulb showing a reduced abaxial ocellum (arrowhead). Scale bars: A) 0.5 mm; B-D, G) 0.2 mm; E, F) 0.1 mm; H-J) 5 Μm; K, L) ~ 1 mm; M) ~ 0.3 mm.

FIGURE 8 Zancleopsis cabela. Polyps from A) Saudi Arabia and B, C) Maldives.D) Tentacle with terminal and sub-terminal capitula. E) Maldivian polyp with medusa buds.F) Large stenoteles (ls), medium-sized stenoteles (ms), small stenoteles (ss), and desmonemes (d). G) small stenoteles (ss) and microbasic euryteles (e). H, I) Female and male medusae, respectively. Details of J) manubrium with female gonads and K) tentacles. Scale bars:A-C, E) 0.2 mm; D) 50 Μm;F, G) 5 Μm; H-K) ~ 1 mm.