Integrative systematics illuminates the relationships in two sponge-associated hydrozoan families (Capitata: Sphaerocorynidae and Zancleopsidae) Author Maggioni, Davide Author Schuchert, Peter Author Arrigoni, Roberto Author Hoeksema, Bert W. Author Huang, Danwei Author Strona, Giovanni Author Seveso, Davide Author Berumen, Michael L. Author Montalbetti, Enrico Author Collins, Richard Author Galli, Paolo Author Montano, Simone text Contributions to Zoology 2021 2021-11-02 90 487 525 http://dx.doi.org/10.1163/18759866-bja10023 journal article 10.1163/18759866-BJA10023 1875-9866 8343324 Kudacoryne diaphana Maggioni sp. nov. http://zoobank.org/ urn:lsid:zoobank.org:act: 741D2566-6F92-408B-AE3A-261A7A6F19E9 Type Material : Holotype – Sample KA079, Saudi Arabia , 16/12/2015 , polyps in formalin and ethanol ( MHNG-INVE-0137429 ) . Paratype – Sample MA0117113, Maldives , 09/02/2017 , polyps in formalin and ethanol ( MHNG-INVE-0137428 ) . Examined material : Sample FB 011, Saudi Arabia , 30/04/2017 , polyps in ethanol and formalin. – Sample FB 056, Saudi Arabia , 01/05/2017 , polyps in ethanol and formalin. – Sample FB 138, Saudi Arabia , 03/05/2017 , polyps in ethanol and formalin. – Sample FB 143, 03/05/2017 , polyps in ethanol and formalin. – Sample FB 190, 04/05/2017 , polyps in ethanol and formalin. – Sample KA 083, Saudi Arabia , 16/12/2015 , polyps in ethanol and formalin. – Sample KA 088, Saudi Arabia , 16/12/2015 , polyps in ethanol and formalin. – Sample KA 089, Saudi Arabia , 16/12/2015 , polyps in ethanol. – Sample KA 090, Saudi Arabia , 16/12/2015 , polyps in ethanol. – Sample KA 093, Saudi Arabia , 16/12/2015 , polyps in ethanol and formalin. – Sample KA 114, Saudi Arabia , 14/12/2015 , polyps in ethanol and formalin. – Sample KA 129, Saudi Arabia , 15/12/2015 , polyps in ethanol and formalin. – Sample KA 173, Saudi Arabia , 17/12/2015 , polyps in ethanol. – Sample KA 177, Saudi Arabia , 17/12/2015 , polyps in ethanol. – Sample KA 180, Saudi Arabia , 17/12/2015 , polyps in ethanol. – Sample MA 16021, Maldives , 25/01/2016 , polyps in ethanol. – Sample MA 16050, Maldives , 08/02/2016 , polyps in ethanol and formalin. – Sample MA 16051, Maldives , 08/02/2016 , polyps in ethanol and formalin. – Sample MA 16064, Maldives , 31/03/2016 , polyps in ethanol. – S ample MA0416125, Maldives , 17/04/2016 , polyps in ethanol and formalin . 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. Description: Polyp . Colonies monomorphic ( fig. 3A ), living in symbiosis with sponges, and occasionally sharing the host with other hydrozoan species (e.g., Zancleopsis cabela in the Maldives ). Hydrorhiza tubular, branched, covered by thin perisarc, extending within the sponge host. Pedicels short (up to 180 Μm), unbranched, covered by a thin perisarc, often overgrown by the sponge. Hydranth pyriform, up to 0.7 mm long, with variable diameter (50–230 Μm) ( figs. 3 A-D). Hypostome proboscis-like, contractile ( fig. 3E ). Up to 22 tentacles arranged irregularly in 2–3 close whorls in the broadest part of the polyp, with the distal whorl directed upward ( figs. 3 A-D). Tentacles 100–300 Μm long. Each tentacle with a terminal, nematocyst-rich capitation (diameter: 70–100 Μm) ( fig. 3F ). Up to two medusa buds at different stages of maturation develop above tentacles, singly on blastostyles ( fig. 3G ). Living hydranths transparent, with white mouths ( figs. 3 A-D). Desmonemes, small and large stenoteles ( fig. 3I ) occurring in the capitula, as well as scattered in the hydrorhiza; macrobasic mastigophores ( fig. 3J ) occurring in the pedicel and hydrorhiza. Newly liberated medusa . Bell-shaped umbrella, 370–410 Μm wide and 405–420 Μm high, with several nematocysts scattered on the exumbrella ( fig. 3H ). Manubrium cylindrical, about 300 Μm long, 2/3 to 3/4 of the bell height,distally provided with a circular mouth. Four radial canals ending in four bulbs with a diameter of 70–80 Μm, containing nematocysts. When released, medusae with no tentacles and no ocelli. Living medusae transparent with reddish manubrium. Microbasic mastigophores and small stenoteles scattered on the exumbrella and large stenoteles in bulbs. Polyp and newly released medusa cnidome . i) Desmonemes(undischarged:9–10 × 4–5 Μm; discharged capsule: 6 × 4 Μm). ii) Macrobasic mastigophores (undischarged: 10–11 × 5–6 Μm; discharged capsule: 8‒9 × 5 Μm; shaft: 45–55 Μm). iii) Microbasic mastigophores (undischarged: 8 × 4–5 Μm; discharged capsule: 7 × 4 Μm; shaft: 5–8 Μm). iv) Large stenoteles (undischarged: 18–20 × 12–14 Μm; discharged shaft: 16–17 × 11 Μm). v) Small stenoteles (undischarged: 10–13 × 7–10 Μm; discharged capsule: 7–11 × 5–8 Μm). Etymology : The species name derives from Greek diaphanes , referring to the absence of a typical colouration of polyps, being almost completely transparent. Distribution : Red Sea and Indo-West Pacific ( Saudi Arabia ; Maldives ). Remarks : The polyps of this species largely agree with the description of other sphaerocorynid polyps. The main differences to other species rely on the colour and size of polyps, being transparent, smaller, and with shorter pedicels in Kudacoryne diaphana . Additional differences are in medusa buds, being in this species up to two in number, not in clusters, and giving rise to free-swimming medusae. Given these differences, and the divergent position in the proposed phylogenetic hypotheses, the new genus Kudacoryne was established (authored by Maggioni). However, we admit that the morphological differences are minimal and likely not useful to distinguish the genera in practice. Therefore, we resorted to a more objective genetic diagnosis. Since the adult medusa of Kudacoryne diaphana is currently unknown, it is possible that this species will later be synonymised with a Sphaerocoryne or Euphysilla species with a name that is based on the medusa stage, but for which no genetic data are available yet.