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

Middle Triassic (Anisian) nautilid cephalopods from Aszófő Genus Pleuronautilus MOJSISOVICS, 1882 Pleuronautilus mosis MOJSISOVICS, 1882 (Plate II: 4) 1882 Pleuronautilus Mosis E. v. MOJSISOVICS. — MOJSISOVICS, p. 274, pl. LXXXV, fig. 3a-b. 1896 Pleuronautilus Mosis MojS. — HAUER, p. 10 [246], pl. Ill, figs 3-6. 1916 Pleuronautilus Mosis MojS. — LÓCZY, p. 109. 1923 Pleuronautilus Mosis E. VON MOJSISOVICS — LUNIEWSKl, p.74, pl. I. non 1926 Pleuronautilus cf. Mosis MOJS. — ALMA, p. 114, pi. 10, fig. 1. Material — Three specimens; one incomplete phragmocone and two body chamber fragments. Measurements: D WH WW u UP M.99.118. — 27 — — — Description — The specimens are rather smallsized for the genus. The whorls are moderately depressed; the cross-section is subquadratic. The umbilical wall is steep and smooth; the umbilical edge is well defined. The flanks are flat and pass rather gradually into the moderately rounded venter. The flanks are ornamented with strong ribs and nodes. The posteriorly concave ribs project over the umbilical margin and pass into bullae at their ventral ends at about the 3/4 height of the flank. Here a longitudinal groove divides the ventral ends of the ribs from the row of the very strong ventrolateral nodes. A 1/4 whorl of the body chamber bears approximately 8 ribs and 10 ventrolateral nodes. The ventral part shows fine, dense, posteriorly arched riblets (growth lines?). Suture lines are not visible. Remarks — There are two, closely related species of Pleuronautilus, both described by MOJSISOVICS in 1882: P. mosis and P. trinodosus. The main difference between them clearly shown on the original figures, lies in the much coarser ornamentation of P. trinodosus showing two independent ventrolateral rows of strong nodes separated by two longitudinal grooves from each other and from the ventral ends of the strong lateral ribs, instead of only one row of nodes and one groove in P. mosis. On the basis of the latter character, our specimens can be ranged into P. mosis and the specimen figured by ALMA (1. c.) can be excluded from here. However, from the point of view of the coarseness of the ornamentation, the Aszófő specimens stand between P. mosis and trinodosus, perhaps closer to the latter. The Aszófő specimens seem to form a morphological group with those figured by HAUER (1. c, figs 3-4), LUNIEWSKl (1. c.) and DziK (1984, fig. 61, pi. 43, fig. 8, as P. trinodosus), where the coarseness of the ornamentation (e.g. the number of ribs) is in inverse correlation with the number of rows of nodes. The specimen figured by ALMA (1. c.) shows also transitional, though different, characters. These forms may fill the morphological gap between P. mosis and trinodosus, which may perhaps be united after a more detailed morphological study of the original material. The specimen mentioned from Felsőörs in the faunal list by LÓCZY (1. c.) (deposited in the collections of the Hungarian Geological Survey under the inventory number T 3376) and studied earlier also by MOJSISOVICS (1882, p. 275) belongs to the "transitional" group with fewer and coarser ribs. The specimen was first determined by J. BÖCKH, whose handwriting can be identified on the original label with the statement: "A köldök bordásabb voltánál fogva látszik nekem Pl. mosistól eltérni." [i.e.: "This seems to me to deviate from PL mosis by its more strongly ribbed umbilicus."] Distribution — P. mosis was described from the Middle and Upper Anisian of the Alps, Dinarides, Balaton area and southern Poland. Our specimens were collected from beds 3, 4 and 26 of Aszófő I. section (Balatonicus Subzone of the Balatonicus Zone). Genus TrachynautUus MOJSISOVICS, 1902 Trachynautilus cf. nodulosus (ARTHABER, 1896) (Plate II: 5a-b) 1896 Pleuronautilus nodulosus ART. — ARTHABER, p. 36, pl. II, figs 7a-b. Material — Two incomplete specimens. Measurements: D WH WW U UP M.99.119 38 18 (47) 19 (50) 14 (37) — Description — The better-preserved specimen is an incomplete cast of a body chamber with some remnants of the calcite-filled phragmocone. It is rather large-sized for the genus. The coiling is moderately evolute (convolute). The whorl-section is subquadrate; the venter is slightly arched, the lateral parts are vertical (parallel). The umbilical wall is steep; the umbilical margin is rather marked. The flank is ornamented with