Euphysilla pyramidata Kramp, 1955

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 : 504-506

Euphysilla pyramidata Kramp, 1955

Euphysilla pyramidata Kramp, 1955: 245 , pl. 1 fig. 1 , pl. 2 fig. 3 ; Kramp, 1965: 4; Vannucci & Santhakumari, 1969: 40; Schmidt, 1973: 16; Hamond, 1974: 554, figs 4–6 ; Segura-Puertas, 1984: pl. 2 fig. 2 ; Buecher & Gibbons, 2000: 127; Xu & Huang, 2004: 560, fig. 9 ; Schuchert & Collins, 2021: 265 , fig. 17.

Sphaerocoryne sp. Di Camillo et al. 2008: 1591; Maggioni et al. 2017: 737.

Examined material: Sample sp002, Maldives, April 2015, polyps in ethanol. – Sample MA 16001, Maldives, 19/01/2016, polyps in ethanol and formalin. – Sample MA 16007, Maldives, 21/01/2016, polyps in ethanol. – Sample MA 16014, Maldives, 22/01/2016, polyps in ethanol and formalin. – Sample MA 16022, Maldives, 25/01/2016, polyps in ethanol and formalin. – Sample MA 16039, Maldives, 29/01/2016, polyps in ethanol. – Sample MA 16054, Maldives, 09/02/2016, polyps in ethanol and formalin. – Sample MA 0117032, Maldives, 31/01/2017, polyps in ethanol. – Sample MA 0117133, Maldives, 13/02/2017, polyps in ethanol and formalin (MHNG-INVE-0137430). – Sample STE040, Sint Eustatius, 18/06/2015, polyps in ethanol.– Sample BFLA4396 , off Florida, 17/05/2020, medusa in ethanol and in situ photos. – Sample BFLA4397 , off Florida, 17/05/2020, medusa in ethanol and in situ photos. – Sample BFLA4478 , off Florida, 18/06/2020, medusa in ethanol and in situ photos.

Description: Polyp. Colonies monomorphic, living in association with sponges and occasionally growing on carbonatic rock ( fig. 4A-C). Hydrorhiza tubular, branched, covered by perisarc and growing in the sponge host. Pedicels long (up to 5 mm), unbranched, covered by a smooth, thin perisarc ( fig. 4A ), occasionally highly covered by debris ( fig. 4C ). Hydranth pyriform, up to 2.5 mm long, with variable diameter (150–420 Μm) ( figs. 4 A-D), in some cases directed at an angle of 90° to the pedicel ( figs. 4B, C ). Hypostome proboscis-like, contractile, with a band of nematocysts below the mouth ( fig. 4E ). Up to 45 tentacles arranged in 3–5 close whorls in the broadest part of the polyp, and grouped longitudinally ( fig. 4F ). Each tentacle with a terminal, nematocyst-rich capitulum (diameter: 100–140 Μm in the distal whorls; 85–95 Μm in the proximal whorl). Tentacles up to 600 Μm long in the distal whorls, shorter in the proximal whorl. Up to seven medusa buds at the same stage of maturation develop above distal tentacles, singly on blastostyles ( fig. 4G). Living hydranths with white mouths, an irregular yellow-orange band below the hypostome, at the level of the gastric cavity, and white, clearly visible, mesenteries ( figs. 4A-D). Small and large stenoteles ( fig. 4H ) and desmonemes ( fig. 4I ) occurring simultaneously and concentrated in the capitula, and rarely also scattered in the hydrorhiza and in the hydranth; heteronemes rarely found in the hydrocaulus ( fig. 4J ); small stenoteles in a band around the hypostome.

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Polyp cnidome. i) Desmonemes (undischarged: 10 × 4–5 Μm; discharged capsule: 8 × 5 Μm). ii) Heteronemes (undischarged: 16 × 7). iii) Large stenoteles (undischarged: 22–24 × 12–15 Μm; discharged capsule: 19–21 × 12–13 Μm). iv) Small stenoteles (undischarged: 11–14 × 8–10 Μm; discharged capsule: 10 × 7–8 Μm).

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Adult medusa (from Schuchert & Collins, 2021). Umbrella 2–4 mm in height, oviform, with apical thickening of very variable height, lateral walls thin, exumbrella with scattered nematocysts ( fig. 4K, L ). Above manubrium an apical chamber, without apparent connection to gastric cavity, size variable depending on size of apical process. Manubrium an inverted cone, as long as bell cavity, base broad and cruciform in life, more square-shaped when preserved, upper part of manubrium cylindrical, narrowing to tubular lower part of manubrium ending in small, circular mouth. All observed medusae were budding medusae, buds in groups on all four perradial sides of the manubrium in about the middle of the manubrium. Gonad-like opaque tissue layer covers manubrium above buds. Colour of manubrium intensively yellow-orange. Radial canals connected to manubrium by apparent short mesenteries (giving cruciform manubrium base), thin; circular canal more rectangular than circular. Four tentacles, contracted about half the length of the bell height, each with 8–12 crescent-shaped, clasping nematocyst pads, all in one row on adaxial side, terminal button ovoid, as wide as rest of tentacle. Four tentacle bulbs relatively small, orange-yellow, with inconspicuous orange-yellow dots on abaxial side of tentacle bulbs resembling reduced ocelli ( fig 4M ).

Adult medusa cnidome (preserved material). i) Desmonemes (4 × 9 µm). ii) Small stenoteles (7 × 10 µm). iii) Large stenoteles (12 × 13 µm). iv) Spherical microbasic euryteles with barbed filament, shaft appears without barbs (7 × 10 µm).

Distribution: Atlantic Ocean and Caribbean Sea ( Benin, Florida; Sint Eustatius), Red Sea and Indo-West Pacific (Northern Red Sea; Australia, India, Indonesia, Madagascar, Maldives, South Africa, Taiwan Strait), and East Pacific. The records from Papua New Guinea may refer to another species ( Schuchert & Collins, 2021).

Remarks: The polyp stage of E. pyramidata is herein described for the first time, and largely resembles Sphaerocoryne and Kudacoryne polyps. However, differences are found in the colouration of the hydranth, tentacle organisation, lack of inclusions in the capitula, and organisation and number of medusa buds. It is possible that polyps of this species were assigned to the genus Sphaerocoryne in previous works, as for instance Sphaerocoryne sp. from Indonesia by Di Camillo et al. (2008) (CG Di Camillo, pers. comm.). The medusa shows strong similarities to Sphaerocoryne medusae as well, but is distinguished by the absence or reduction of ocelli and the common presence of medusa buds on the manubrium. Schuchert & Collins (2021) initially detected the genetic similarities in the 16S rRNA region between a Sphaerocoryne polyp from Maldives ( Maggioni et al., 2017) and E. pyramidata medusae from Florida, here confirmed on the basis of multiple DNA regions and phylogenetic analyses. They also suggested that E. pyramidata in the sense of Bouillon (1978) may be a species complex due to morphological differences, but further sampling is still needed to address this issue.

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 5 Euphysilla sp. A, B) Ethanol-fixed polyps from Martinique.C) Desmonemes, D) small and E) large stenoteles, and F) heteronemes from the polyp. Scale bars:A, B) 50 Μm;C-F) 5 Μm.

FIGURE 6 Heterocoryne caribbensis. A-C) Polyps from Sint Eustatius. D, E) Tentacles partially fused. F) Large stenoteles (ls), small stenoteles (ss), and desmonemes (d). Scale bars: A-C) 0.5 mm; D, E) 0.1 mm; F) 5 Μm.

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.