Szabó János szerk.: Fragmenta Mineralogica Et Palaentologica 19. 2001. (Budapest, 2001)

VÖRÖS, A. Genus Encoiloceras HYATT in ZlTTEL, 1900 Encoiloceras was used for a long time as subgenus of Pleuronautilus (see e.g. DI EN ER 1915, p. 346 and KUTASSY 1932, p. 728); in the "Treatise", KUMMEL (1964) put it on the rank of genus. DZIK (1984, p. 173) regarded Encoiloceras as synonym of Anoploceras without any reasoning or comment. In the present paper, the systematics of the "Treatise" is accepted and Encoiloceras is used as an independent genus characterized mainly by its large umbilical perforation and slender, evolute whorls. Earlier authors (cited above) agreed that Encoiloceras was restricted stratigraphically to the Carnian. The two new species described below came from the Anisian; their attribution to Encoiloceras expands considerably the stratigraphie range of the genus downward, apparentiy without record in the Ladinian. It is probable that Encoiloceras was more widespread in the Middle Triassic: e.g. the species "Temnocheilus (Pleuronautilus ?) quadrangulus" HAUER, 1892 and "Temnocheilus triserialis" HAUER, 1896 described from the Bosnian "Muschelkalk" may well belong to this genus. Encoiloceras balatonicum sp. n. (Plate I: 2, 3a-b; Figure 3) Holotype — Plate I: 2, Figs. 3A, C (M.99.105.) Paratype — Plate I: 3a-b, Fig. 3B (M.99.106.) Type locality — Aszófő, Farkó-kő (Balaton Highland, Hungary) Type strata — Brownish-grey, well-bedded limestone, Balatonicus Subzone of Balatonicus Zone. Derivation of name — After the Lake Balaton. Diagnosis — Very evolute and slender Encoiloceras with extremely wide umbilical perforation; height and width of whorls are nearly equal; ventrally widening, trapezoidal cross-section; flanks with strong ventrolateral and weak umbilical nodes. Material — Two incomplete specimens. Measurements: D WH WW U UP Holotype 69 21.8 (31.6) 25.6 (37.1) 33.3 (48.3) 18.2 (26.4) 41 13.6 (33.2) 15 (36.6) 20.7 (50.5) 15.2 (37.1) Description — The holotype is a medium-sized, incomplete internal cast with some remnants of silicified shell material of the phragmocone. The body chamber is partly worn and its adorai part is broken. The coiling is very evolute; the slender whorls are in contact, but overlap only very

7 slightly. There is an extremely wide umbilical perforation. The whorl-section is subquadratic, trapezoidal, and much wider ventrolaterally than at the umbilical margin. The umbilical wall is steep; the umbilical edge is well defined. The venter is arched, with a slight depression at the middle. The ornamentation of the lateral flanks consists of nodes. There is a row of regularly spaced, weaker nodes at the umbilical margin. The ventrolateral part of the phragmocone is ornamented with a double row of nodes; the double nodes coalesce toward the end of the phragmocone and appear as strong tubercles on the body chamber. Blunt radial ribs connect the umbilical and ventrolateral nodes. A half whorl of the phragmocone bears 10 ribs/nodes. Suture lines are very simple, having shallow lateral lobes and wide, arched ventral saddle without ventral lobe. The internal lobe is not visible. Remarks — E. balatonicum differs from E. superbum (Mojsisovics, 1873), the type species of the genus, by its more evolute and slender whorls, more trapezoidal whorl-section and its ornamentation (nodes and tubercles instead of coarse ribs). Furthermore, E. superbum is Figure 3 — Cross-sections and suture line of Encoiloceras balatonicum sp. n. — A: cross-section of the holotype (M.99.105), Aszófő I (scree), Balatonicus Zone (Balatonicus Subzone), B: cross-section of the paratype (M.99.106), Aszófő I, Bed 5, Balatonicus Zone (Balatonicus Subzone), C: suture line of the holotype at WH=13 mm.