Van Kampen, 1922
Description
Umbrella hemispherical with thick apical jelly, much thinner at sides [E.flevensis-1 ] with four simple radial canals. Gastric peduncle absent, manubrium small, without black spots in preserved specimens (but present in fresh ones). Marginal tentacles 16, clearly separated from the bulbs; each tentacle bulb with two pairs of lateral cirri [E.flevensis-2 ]. Eight vesicular statocysts [E.flevensis-3 ].
Original drawings of subumbrellar view E.flevensis-su and tentacle bulb E.flevensis-tb.
Size
Umbrella diameter of type specimen was about 6 mm, but Tulp (2001a) reported 16 mm as largest diameter.
Ecology and depth range
Coastal, mainly in brackish waters.
Distribution in the North Sea
Described from the brackish Zuiderzee, the present-day Dutch freshwater lake IJsselmeer, E. flevensis was only known from the type locality (Van Kampen, 1922) and not recorded again after. The species has recently been re-discovered on the Dutch North Sea coast and in various brackish waters in the Netherlands (Tulp, 2001a).
World distribution
Unknown, except for the Dutch references in the previous section.
Remark
Tulp, 2001a reported catches of Eucheilota medusae from the Waddenzee which display the black spots on the stomach as described typically for Eucheilota maculata. However, these medusae bear two cirri on each side of the tentacle bulb, conform E. flevensis whereas Eucheilota maculata has only one cirrus on each side of the tentacle bulb. E. flevensis has been described without black stomach spots, however, from preserved specimens. This stomach pigmentation may be lost and therefore should be discarded as a distinguishing character for both species. Tulp, 2001a concluded that E. flevensis is not extinct, which is the reason for incorporating this species in this volume.