Euphysilla 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 : 506-507

Euphysilla sp.

Sphaerocoryne cf. agassizii . Miglietta et al. 2018: 105, suppl. data, p. 27.

Examined material: Sample BT 012, Panama, August 2015, polyps in ethanol. –BT015, Panama, August 2015, polyps in ethanol. – Sample AL 04, Martinique, 30/01/2014, polyps in ethanol (MHNG-INVE-0137432) .

Description: Polyp. Colonies monomorphic, living in association with sponges. Pedicels long (up to 8 mm), unbranched, covered by a smooth, thin perisarc ( fig. 5A ). Hydranth pyriform, up to 0.3 mm long when contracted, with a proboscis-like hypostome ( fig. 5B ). Up to 40 tentacles whose arrangement was not clear in preserved specimens, each with a terminal, nematocyst-rich capitulum. Small ( fig. 5C ) and large stenoteles ( fig. 5D ) and desmonemes ( fig. 5E ) occurring simultaneously and concentrated in the capitula, found also in the hydrocaulus; heteronemes rarely found in the hydrocaulus ( fig. 5F ).

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

Distribution: Currently only known from the Caribbean Sea ( Martinique, Panama).

Remarks: This species was identified as belonging to the genus Euphysilla based on genetic data alone, since no comprehensive information on its polyp stage was available (e.g., colour of living polyps). Additionally, the medusa stage is currently unknown. However, the general morphology and the cnidome composition and size are comparable to those of E. pyramidata . Other than E. pyramidata , the genus Euphysilla currently includes two additional species, namely E. peterseni Allwein, 1967 , and E. tubularia Huang, Xu & Lin, 2015 , from NW Atlantic and China Sea, respectively ( Allwein, 1967; Huang et al., 2015). Morphological differences among the medusae of Euphysilla species are only slight and they might represent intraspecific variation. However, the finding of another Euphysilla species based on genetic data may support the presence of multiple species, and our material may be later demonstrated to be conspecific with E. peterseni , E. tubularia , or other species. The medusae identified by Bouillon (1978) as E. pyramidata lack an apical chamber and have a different bell shape. It is likely distinct from E. pyramidata and thus another potential candidate that could be the medusa of the present species.

Figures

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.