Lyckholmoceras Teichert, 1930

Genus Lyckholmoceras Teichert, 1930

Type species

Lyckholmoceras estoniae Teichert, 1930 , from Saaremõisa (Lyckholm), N of Haapsalu, Läänemaa, Estonia, Kõrgessaare Formation, Vormsi Regional Stage; by monotypy.

Emended diagnosis

Slightly endogastrically curved, large brevicones with slightly compressed conch cross section, conch margin narrower at ventral side; mature body chamber uncontracted or at mid-length, with distinct hyponomic sinus; sutures with shallow lateral lobe; siphuncle marginal with slightly expanded segments; endosiphuncular bullettes occur.

Remarks

The genus was placed within the Cyrtogomphoceratidae by Flower in Flower & Teichert (1957) and without further discussion classified within the Diestoceratidae in Sweet (1964b: K295). Both families contain genera with swollen siphuncles and with annulosiphonate deposits or endosiphuncular bullettes. However, here I follow Teichert (1964b) to restrict the cyrtogomphoceratids to endogastrically curved and the diestoceratids to straight and exogastrically curved forms (see above). Hence, Lyckholmoceras is interpreted as a member of the Cyrtogomphoceratidae , herein.

The original diagnosis is emended herein regarding the presence of endosiphuncular deposits. In Teichert (1930: 301) it is stated “Keine Ausfüllungen des Siphos bekannt” (translated from German: “Endosiphuncular deposits unknown”. This statement was emended by Sweet (1964b: K295) to “actinosiphonate deposits not known”. In the Estonian material, assigned to Lyckholmoceras , studied herein, endosiphuncular bullettes occur. The genus diagnosis is changed accordingly.