Ptychogena crocea Kramp & Dumas, 1925

Peter Schuchert, 2017, Systematic notes on some leptomedusa species with a description of Neotima galeai n. spec. (Hydrozoa, Cnidaria), Revue suisse de Zoologie 124 (2), pp. 351-375 : 356

Ptychogona crocea Kramp & Dumas, 1925: 290 , pl. 1 figs 1-7. ‒ Kramp, 1933: 558, fig. 21. ‒ Russell, 1940: 519, figs 18-19. – Rees, 1952: 5. – Kramp, 1959a: 137, fig. 158. – Kramp, 1961: 146. ‒ Schuchert et al., 2017: 168, figs 3-4.

? Ptychogona crocea . ‒ Léon et al., 2007: 57, photo 1.

in part Lafoea plicatilis M. Sars, 1863: 31 .

in part Stegopoma plicatile . – Kramp, 1913: 15, figs 1-2. – Broch, 1918: 26, fig. 8. – Edwards, 1973a: 590. – Cornelius, 1995: 114, fig. 25. – Schuchert, 2001: 51, fig. 37A-E. ‒ Schuchert et al., 2017: 168, fig. 4.

Material examined: MHNG-INVE-94101, 1 fully grown, formalin preserved specimen of a catch of about 10 specimens; Norway, Korsfjord, 60.1846°N 5.196°E, 0-600 m depth; collection date 14.06.2016; other, younger specimens were used to extract DNA and RNA; sample DNA sample 1163 giving 16S sequence KY363953 , 18S KY363983 ; DNA sample 1195 resulting in 16S sequence KY363958 ; DNA sample 1196 giving 16S sequence KY363959 (16S all identical, see Schuchert et al., 2017).

Diagnosis: Umbrella up to 25 mm wide, height 15 to 25 mm but often flatter than a hemisphere (depending on state of contraction and health). Jelly thick, apical jelly about one third of bell height. Stomach relatively large, prismatic, attached to subumbrella via crossshaped base, mouth wide, irregular. Four radial canals, transparent but relatively thick in distal half or third of radius, connected to stomach via a funnelshaped, laterally compressed, mesentery-like basal outgrowth of the manubrium, this structure bears on both sides up to 7 thick, large transverse folds, their upper end not connected to subumbrella and covered by the gonads in a thick layer. Bell margin with up to 80 bulbs of different sizes, about 30 developed into tentacles, others mere marginal warts or rudimentary tentacles and all intermediate stages to fully developed tentacles. Between pairs of tentacles 2-4 cordyli, some attached to bell margin, many also on small marginal warts/rudimentary bulbs. Cordyli club-shaped, with few (<10) nematocysts (about 16 μm long spindleshaped microbasic mastigophores). Colour: stomach, basal extensions, and gonads all with a characteristic, Distribution: Deep waters (0-1000 m) of Norway. ( Kramp & Damas, 1925; Kramp, 1961) and off the south-west coast of Scotland ( Fraser, 1974). A single, much damaged specimen has also been recorded from deep waters of the Cape Verde Islands and three specimens from the Gulf of Maine ( Léon et al., 2007). Type locality: Norway, Romsdal, deep waters of Moldefjord.

Figures

Fig. 4. Ptychogena crocea, after living and preserved specimens from Norway. (A) Lateral view. The slight concave lateral walls are a typical sign of beginning deterioration. (B) Stomach and gonads in aboral view. (C) Bell margin seen from oral side (not to scale with A). Abbreviations: cc ‒ circular canal, cor ‒ cordylus, ex ‒ exumbrella, rc ‒ radial canal, rt ‒ rudimentary tentacle or marginal wart, te ‒ tentacle, ve ‒ velum. (D) Cordylus.