Nausithoe racemosa ( Komai, 1936 )

Molinari, Clarissa G., Collins, Allen G. & Morandini, André C., 2023, A morphological review of the jellyfish genus Nausithoe Kölliker, 1853 (Nausithoideae, Coronatae, Scyphozoa, Cnidaria), Zootaxa 5336 (1), pp. 1-32 : 20-22

Nausithoe racemosa ( Komai, 1936)

( Fig. 13 )

Stephanoscyphus racemosus Komai, 1936: 182 .

Nausithoe racemosa — Jarms, 1990: 11.

Holotype not known, possibly not extant.

Material examined: Living polyps kept in laboratory cultures (Shirahama, Japan, 2004; 5m depth; S. Kubota col.) .

Diagnosis: medusoid—no gastric filaments, developed mouth or tentacles; polyp—colonial without internal cusps and broad oral disc with small tentacles.

Description: Based on original description, and Werner (1970, 1971, 1973). A reduced medusa, medusoid with no gastric filaments, developed mouth or tentacles; males develop four elongated gonads while in the strobilation chain, so that the upper distal medusoid releases the spermatozoa before the others; females detach before shedding the large size eggs from the mouth, embedded in a mucus strand with nematocysts; the medusoid has a welldeveloped muscular system, but is not able to swim. Polyp colonial; there is a central/primary polyp from which secondary polyps emerge, as a “stem with nodes”, not randomly, but at an oblique angle; no internal cusps; soft body with enlarged oral crown, broad ring around the mouth and small delicate tentacles; the tentacle’s crown has kind of a square shape; dark yellow/brown coloration of tissues due to the large amount of as-yet uncharacterized algal symbiont.

Type locality: Seto, Japan.

Distribution: Japan, NW Pacific Ocean (shallow waters).

Remarks: This species is easily differentiated from other Nausithoe because of the colony’s structure and the polyps’ enlarged oral crown and small tentacles.

Figures

FIGURE 13. Nausithoe racemosa. A—Images adapted from Werner (1971, fig. 3, 4, 5); a: male polyp shedding off spermatozoa from the central opening of the operculum; b: female polyp showing the distal eumedusoid outside the tube; c: female eumedusoid releasing eggs embedded in a mass of mucus. B and C—Polyp colony, pointing to one individual polyp. D—Oral view of polyp showing the flat extended collar with the mouth (mo) and small tentacles (t).