Turritopsis nutricula McCrady, 1857

Schuchert, Peter & Collins, Richard, 2021, Hydromedusae observed during night dives in the Gulf Stream, Revue suisse de Zoologie 128 (2), pp. 237-356 : 256-257

Turritopsis nutricula McCrady, 1857

Fig. 11 A-D

Oceania (Turritopsis) nutricula McCrady, 1957: 55 , pl. 4 figs 1-10.

Turritopsis nutricula . ‒ Brooks, 1883: 465. ‒ Brooks, 1886: 388, pl. 37. – Brooks & Rittenhouse, 1907: 429, pls 30- 35, development. – Mayer, 1910: 143, figs 10-13, pls 14-15. – Goy, 1979: 270, fig. 4. – Wedler & Larson, 1986: 86, fig. 5B. – Schuchert, 2004: 327, figs 2A- B, 3D-E, revision. – Miglietta et al., 2018a: fig. 2. – Calder, 2019: 12 , fig. 1e.

Modeeria multitentaculata Fewkes, 1881: 149 , pl. 3 figs 7-9.

Examined material: BFLA4391 ; 1 specimen; 17 -MAY-2020; size 3 mm; preserved in alcohol for DNA extraction; 16S sequence MW528718 . – BFLA4416 ; 1 specimen; 28 -May-2020; size 2 mm; preserved in alcohol for DNA extraction; 16S sequence MW528724 .

Observations: Typical Turritopsis medusae, bell heights up to 3 mm, manubrium yellow, blocks of vacuolated cells at manubrium base with deep interradial clefts, thus clearly separated ( Fig. 11 B-C), tentacle numbers about 50, base with an adaxial ocellus, tentacle tips swollen in life. Nematocyst buttons lining the mouth margin with stalks like in Oceania armata .

16S Data: The two 16S sequences obtained had only 0.5% base pair divergence. In order to compare them to other existing sequences, they were added to the set of sequences used in Miglietta et al. (2018a) and a maximum likelihood phylogenetic analysis was made (results not shown). Both sequences of this study clustered with sequences of T. nutricula from Woods Hole (GenBank numbers EU624349 and EU624348 ) and others from Panama (e.g. EU62435), thus fall within the clade of T. nutricula of Miglietta et al. (2018a).

Distribution: Temperate to tropical coastal regions of the western Atlantic Ocean from Woods Hole to Brazil, Gulf of Mexico, Caribbean Sea. Type locality: Atlantic Ocean, USA, South Carolina, Charleston Harbor.

Remarks: The samples examined here matched unambiguously Turritopsis nutricula in the restricted sense of Schuchert (2004). The yellow manubrium and particularly the interradially split blocks of vacuolated cells at the manubrium base are diagnostic for Turritopsis medusae of this region. Moreover, the sampling site is in the same biogeographic region as the type locality, the latter being about 800 km away. There can thus be little doubt that these specimens represent the true T. nutricula .

Species delimitation in the genus Turritopsis was difficult and until the revision of Schuchert (2004) most authors assumed that there is only a single, circum-globally occurring species named T. nutricula . Schuchert (2004) using morphological data showed that this is not the case and re-established several previously synonymized names. This was then later confirmed using genetic data [see summary in Miglietta et al. (2018a) and references therein]. However, so far it was not clear which of the molecular clades corresponded to the true T. nutricula . Although the studies of Miglietta et al. included specimens identified as T. nutricula , their identity was uncertain because they were either based on young medusae or polyps. Both of them are not unambiguously identifiable. The results of the present study confirm the correct identification of the T. nutricula clade in Miglietta et al. (2018a).

Figures

Fig. 11. Turritopsis nutricula. (A-C) Specimen BFLA4416, bell height 2 mm. (D) Specimen BFLA4416, 3 mm height. (A) Oblique view of animal. (B) Oral view, note nematocyst clusters along mouth margin and the interradially separated blocks of vacuolated cells at manubrium base. (C) Oblique view. (D) Lateral view, in the background some appendages of a decapod.