Pandeopsis prolifera, Peter, 2021

Schuchert, Peter & Collins, Richard, 2021, Hydromedusae observed during night dives in the Gulf Stream, Revue suisse de Zoologie 128 (2), pp. 237-356 : 252

Pandeopsis prolifera n. spec.

Fig. 9 A-E

Holotype: BFLA4442 ; collected 07-JUN-2020; size 8 mm; part of specimen preserved in formalin and deposited in Florida Museum of Natural History, catalogue number UF-014057 ; before formalin fixation, about 1/4 of animal was cut and preserved in ethanol for DNA extraction (MHNG-INVE-0137381); 16S sequence MW528727 .

Other examined material: BFLA4260 ; 1 specimen; 07 -MAY-2019; size 5 mm; preserved in ethanol for DNA extraction; 16S sequence MW528695 .

Type locality: USA, Florida, 5.5- 12 km east of Palm Beach; WGS84 26.70, -79.94 to 26.78, -79.94; depth 10 m .

Diagnosis: Pandeopsis medusa with medusa budding on manubrium wall in mature animals, eight tentacles, approximately 24 rudimentary bulbs; stomach base square-shaped in younger animals.

Description: Bell size up to 8 mm, bell higher than wide ( Fig. 9A ), bullet-shaped, jelly very thick, apical jelly takes up about 1/3 of total height, lateral walls also thick. Exumbrella smooth. Manubrium large, squareshaped base in younger individual, more cross-shaped in older specimen ( Fig. 9C ); manubrium with wide upper part (stomach) filling nearly half the subumbrella and attached to it via mesenteries, narrower lower part of manubrium with cross-shaped section, mouth drawn out into four lips with slightly undulated rim; manubrium colourless but with pigment dots ( Fig. 9D ). In holotype interradial stomach wall densely beset with a layer of medusa buds of different developmental stages, about 50 per quadrant, white, in some buds red pigment dots of developing ocelli. Radial canals thick, smooth. Eight tentacles, long, tapering, not much laterally compressed, with red abaxial ocellus at base. 24 adradial rudimentary bulbs with a very short, stump-like tentacle, with abaxial red ocellus ( Fig. 9B, D ).

16S Data: See Fig. 8 , Table 1 , and below under Remarks.

Distribution: Type locality only.

Remarks: Our main argument to separate P. prolifera from P. ikarii is the distinct separation in the phylogenetic analysis ( Fig. 8 ). The observed base pair differences between the two clades were 7.2 to 8.9 %, which is rather large in comparison to the intraspecific variation seen in the other Pandeidae (comp. Fig. 8 ) but could also be in part due to generally longer branches in this cluster.

However, there are also morphological differences between the animals identified here as P. prolifera and P. ikarii :

- medusa buds on manubrium ( Fig. 9A ) versus no buds on manubrium ( Fig. 7 A-B),

- three rudimentary bulbs between tentacle pairs even in younger medusae ( Fig. 9D ) versus one only ( Fig. 7B ), - colourless manubrium ( Fig. 9 ) versus greenish manubrium ( Fig. 7 ).

We acknowledge that all these differences could be due to a low sample number bias and not fully-grown individuals. More samples could blur the differences and require that both morphotypes be regarded as conspecific. The high intraspecific genetic divergence would be surprising though.

Figures

Fig. 9. Pandeopsis prolifera n. spec. (A-C) Holotype, BFLA4442, bell height 8 mm. (D-E) BFLA4260, size 5 mm. (A) Lateral view. (B) Bell margin in oral view. (C) Oblique view on aboral part, note shape of manubrium base which is not obviously squareshaped. (D) Lateral view. (E) Oblique view on aboral part, base is square-shaped, some incipient oocytes are visible, food items are in the lumen.

Fig. 8. 16S rRNA maximum likelihood phylogenetic tree of Pandeidae species obtained with PhyML (GTR+G+I model) and based

Fig. 7. Pandeopsis ikarii. (A-C) Specimen BFLA4088, size 2.5 mm, presumable incipient oocytes are visible in the stomach wall. (D) Specimen collected 08-AUG-2018, size 5 mm, the identification is somewhat unreliable as there is no sequence data available.