Clytia spec.2

Schuchert, Peter & Collins, Richard, 2021, Hydromedusae observed during night dives in the Gulf Stream, Revue suisse de Zoologie 128 (2), pp. 237-356 : 314

? Clytia spec.2

Fig. 46 D-G

Examined material: BFLA4253 ; 1 specimen; 23-NOV- 2019; size 3 mm, with developing gonads; preserved in alcohol for DNA extraction; 16S sequence MW528694 . – BFLA4257 ; 1 specimen; 23-NOV-2019; size 2 mm, with developing gonads; preserved in alcohol for DNA extraction; 16S sequence identical to MW528694 . – BFLA4269 ; 1 specimen; 04-DEC-2019; size 4 mm, with developing gonads; preserved in alcohol for DNA extraction; 16S sequence identical to MW528694 . – BFLA4274 ; 1 specimen; 04-DEC-2019; size 3 mm, with developing gonads; preserved in alcohol for DNA extraction; 16S sequence identical to MW528694 . – 06-DEC-2019; 1 specimen, 6 mm, photographed, not collected; most probably also belongs to this species.

Observations: Umbrella 2 to 4 mm in diameter when gonad development starts, flatter than hemisphere when relaxed, mesoglea moderately thick, thinning towards margin. Manubrium small, urn shaped, with 4 (5?) short perradial lips, margin smooth. Gonads just developing in middle of complete radial canals and also on some incomplete ones. Complete radial canals thin, numbering 5 to 9, originating from manubrium, often irregularly spaced, rarely seen branched, some not entirely straight. With 0 to 15 incomplete centripetal canals originating from circular canal ( Fig. 46D ), usually from marginal bulbs but not always, not reaching manubrium, length variable from very short to about 3/4 of complete radial canal length. 16 to 22 tentacles arising from small conical bulbs, few atentacular bulbs (3-6) present. Usually 2 statocysts between pairs of bulbs, variable from 1 to 4. Colour: Most specimens without colour, one had pink bulbs. A specimen for which no 16S data is available, but which looked otherwise indistinguishable, had two manubria ( Fig. 46G ), one being smaller.

16S Data: The four sequenced specimens gave all the same 16S sequence ( MW528694 ). In a maximum likelihood tree (not shown) obtained by comparing it to the Campanulariidae 16S dataset of Cunha et al. (2017) it came out as sister lineage to a clade tentatively identified as Clytia cf. stolonifera Blackburn, 1938 (GenBank KX665270, KX665268) in Cunha et al. (2017). The base pair divergence between KX665270 and MW528694 is 7.2%.

Remarks: While the 16S data clearly identified it as a Campanulariidae , finding the correct genus of this material was difficult and is still unsettled. A specimen with five radial canals ( Fig. 46F ) suggests that it could be Pseudoclytia pentata Mayer, 1900 , but the presence of centripetal canals is not compatible with this species. Mayer (1910) found and examined an immense number of P. pentata over several years and the number of radial canals was somewhat variable, but he never observed centripetal canals. Mayer’s medusae rarely had two manubria, just like in our case ( Fig. 46G ), although we have no 16S data for this specimen to assure that it is the same species as the others examined here.

Our 16S sequence was relatively similar to sequences obtained from two campanulariid hydroids from Belize that resembled the Australian Clytia stolonifera (see Cunha et al., 2017). The observed divergence of 7.2% represent likely an interspecifc difference when compared to the values of Table 1 , but with so few samples the value is currently inconclusive. In the phylogeny of Cunha et al. (2017), their hydroids did not cluster within the Clytia clade, but had an ambiguous phylogenetic position, frequently placed at the base of Obeliinae . This could mean that a genus other than Clytia may be needed for the specimens of Cunha et al. (2017) and also the medusa BFLA4253 of this study. DNA sequence information of the type species of Pseudoclytia and Gastroblasta must be obtained to resolve if one of these genera also belongs to this clade and could be the appropriate genus. For recent discussion of these genera see Gravili et al. (2007).

Figures

Fig. 46. Clytia ssp. (A-B) Clytia linearis, BFLA4077, bell dimeter 3.5 mm. (C) Clytia spec. 1, BFLA4283, bell diameter 10 mm. (D)? Clytia spec. 2, BFLA4274, 3 mm; arrow points to incomplete centripetal canal. (E)? Clytia spec. 2, BFLA4269, 4 mm. (F)? Clytia spec. 2, BFLA4253, 3 mm, has 5 complete radial canals. (G)? Clytia spec. 2, doubled manubrium of animal photographed 06-DEC-2019, 6 mm bell, not collected.