FRAGMENTA MINERALOGICA E T PALAEONTOLOGICA

18. BUDAPEST, 1996 p. 63-70

Some new species of Adeorbisina (Adeorbisininae, Colloniidae, Trochoidea) in the Bajocian gastropod fauna of Somhegy

(Bakony Mts., Hungary)

by

J . Szabó

SZABÓ, J. (1996): Some new species of Adeorbisina (Adeorbisininae, Colloniidae, Trochoidea) in the Bajocian gastropod fauna of Somhegy (Bakony Mts., Hungary). - Fragm. Min. et Pal., 18: 63-70.

Abstract: Three species of Adeorbisina Greco, 1899 is described below as completion to the Bajocian gastropod fauna of Somhegy (Bakony Mts., Hungary). Two of them, Adeorbisina conica sp. n. and Adeorbisina nitens sp. n. are new. Systematics, stratigraphy, paleoecology and paleobiogeography of Adeorbisina is also discussed.

INTRODUCTION

The locality is in the top area of Somhegy, a hill near Bakonybél in the Northern Bakony Mountains within the Transdanubian Central Range (Hungary). The Jurassic strata of Somhegy are strongly discontinuous and consist exclusively of limestones of Mediterranean type pelagic facies in a rather complicate structure. The Bajocian limestones, which contained also a rich, well preserved gastropod fauna (Szabó 1979, 1980, 1981, 1982, 1983, Conti & Szabó 1986), were found as infilling of a multi-phase fissure system. Recent collections in the outcrop resulted some specimens indicative also of new species of the Colloniidae Cossmann, 1916.

Here, the interpretation of the Colloniidae is the same as given by Monari, Conti & Szabó (1996) after recognition of close phylogenetic relations between some groups (Szabó, Conti & Monari 1993) that have been separated into independent families.

The holotypes of the new species are deposited in the collection of the Geological and Palaeontological Department of the Hungarian Natural History Museum, Budapest.

Abbreviations for measurements, given in mm: H height of shell HL height of last whorl HP height of peristome W width of peristome D diameter A apical angle SL spiral angle of last whorl(s)

measured on slightly damaged shell part

SYSTEMATICS

Class GASTROPODA, Cuvier, 1797 Order Archaeogastropoda Thiele, 1925

Superfamily Trochoidea Rafinesque, 1815 Family Colloniidae Cossmann, 1916

Subfamily Adeorbisininae Monari, Conti & Szabó, 1996 Genus Adeorbisina Greco, 1899

Adeorbisina was established on a single, imperfectly preserved specimen but the most important feature of the genus, an abaxial deviation from the normal coiling on the last whorl, was clearly visible. Later CONTI & FISCHER ( 1 9 8 1 ) applied a new name, Mariottia, for a species, having also abaxial deviation and a rather different shape. While in the description of Adeorbisina, presence of an umbilicus is mentioned, Mariottia is anomphalous. Unfortunately, because of technical troubles of the depository museum, GRECO'S original specimen cannot be studied recently, therefore the exact relation of the two forms has not yet been checked. Anyway, the systematical importance of presence or absence of an umbilicus is lower than the genus level (CONTI & SZABÓ 1987; HICKMAN & M C L E A N 1990). Therefore the name Adeorbisina is applicable also for the anomphalous forms. However, a final decision about the name "Mariottia" can be given after the comparison of the two type species.

The stratigraphically earliest, Late Pliensbachian, published species of Adeorbisina was described as "Teinostoma macrostoma Stol. sp. var. angulata v. n." by M . GEMMELLARO ( 1 9 1 1 , p 233 , Pl. X . , Fig. 5-6). This species clearly has the most specific character of Adeorbisina, the abaxial deviation from the normal coiling. Comparing the original figure of the referred species (Rotella macrostoma Stoliczka, 1 8 6 1 ) to GEMMELLARO's figures and the originals, deposited at the "Gemmellaro Museum" (University of Palermo), the two species seemed to belong to different genera. In the figures and the description of STOLICZKA'S species, the abaxial deviation does not appear. No abaxial deviation is visible also on STOLICZKA'S originals and a lot of other specimens from Hierlatzberg (deposited in the Museum of the Geologische Bundesanstalt and in the Naturhistorisches Museum, Vienna). These specimens clearly show that "Rotella" macrostoma is in reality a species of Crossostoma Morris & Lycett, 1851 (Crossostomatinae, Colloniidae) without abaxial deviation but with trumpet-like, strongly enlarged peristome (simple in GEMMELLARO's species). However, the last whorl of the Hierlatzberg specimens show definite downward bend in the coiling little before the adult peristome, just on the same shell part where the abaxial deviation of Adeorbisina developes. The downward deviation from normal coiling is rather widespread not only in the Colloniidae but also in many other groups (SZABÓ et al. 1993, MONARI et al. 1996) therefore its systematical value is lower than that of the other deviation type.

The form of the downward bend sometimes makes an impression of Adeorbisina shell in a view, not parallel to the axis. Probably this was the reason of the misidentification or M . GEMMELLARO attributed low systematical value to the differences in the orientation of the deviations. In a true Adeorbisina, the outline of the

deviation swings out of the spiral, followed by the earlier whorls but remains within in case of a simple downward turn.

In spite of the clear differences between GEMMELLARO's and STOLICZKA'S species, the characters in common, especially the similarities in the inner lip (callosity) structure, suggest that Crossostoma macrostoma is one of the possible ancestor forms for Adeorbisina.

Adeorbisina conica sp. n. (Pl. I : 1-4)

Type specimen: Plate I : 1-4 Type locality: Bakonybél, Somhegy. Type strata: condensed limestone; Niortense to Garantiana Zones. Name: referring to the almost regularly conical spire. Diagnosis: high, nearly conical spire; strongly convex, anomphalous base; top of

abaxial deviation sharp, developed at 70° before peristome. Material: A single specimen in which the shell is substituted by micrite; a

ferromanganiferous film is keeping details of the ornament. The protoconch and the outer lip region is lacking but the preserved parts are enough to find specific characters to give a reliable distinction from other species.

Measurements: H HL HP W D A SL

*21 Descrip

*15 tion: Conica

*10 l-turbiniform shell of ty] )ical "Ataphi

73° ^ws-shape" tl

63° iát means a

cyrtoconical spire. Differences from Ataphrus appear at and near the adult aperture. Peristome continuous, inner lip simple and narrow callous band joins it with the base. Callus forms semicircular pad close to the foot of columella. Boundary between callus and base hardly observable. Preserved part of aperture circular. Presumably, as in most species of Adeorbisina, entire aperture also circular. Abaxial deviation terminates in axially flattened, sharp outermost part, bending slightly upward. Basal part of last whorl between aperture and abaxial deviation expands downward. Peristome moderately thickened. Ornament of extremely fine, somewhat prosocline growth lines.

Remarks: The species, most similar to A. conica sp. n. is Adeorbisina gibbosa (Conti & Fischer, 1981) (= Adeorbisina procera Szabó, 1981) but, in the latter species, the whorls are more covex, the suture runs in a deep furrow, the last whorl is rather expanded at the peristome (trumpet-like) and the outermost part of the abaxial deviation does not bend upward. Al l other described species are lower spired than A. conica sp. n. and have abaxial deviation of different morphology. Their deviation is either simple and rounded or with a peripheral carina (spiral angulation) of different length.

Stratigraphical distribution: Condesed Niortense to Garantiana Zones.

Adeorbisina nitens sp. n. (PI. I : 5-8)

Type specimen: Plate I : 5-8 Type locality: Bakonybél, Somhegy. Type strata: condensed limestone; Niortense to Garantiana Zones.

Name: nitens (Lat.) = bright; referring to the glaze-like outer enamel of the shell. Diagnosis: low, conical spire; periphery and abaxial deviation rounded; flattened,

anomphalous base with median depression; peristome slightly thickened. Material: a single, rather badly damaged specimen, showing enough specific

features to establish a new species. Measurements:

H HL HP W D A SL *15

Descrip *12

tion: Low sp *9

ired, turbinil 11.3

brm species, 20.3

having feeb 123°

ly concavo-c 123°

onvex spire whorls; concave band little below incision-like suture. Slightly flattened last whorl with rounded periphery. Arch of whorl surface and base of similar radius. Definite abaxial devation, top of which 75° backward from peristome. No umbilicus on base but only shallow median depression, partly filled by moderately large (semicircular) callus. Peristome somewhat thickened and also depressed but aperture orbicular. Columellar lip with wide, almost flat outer face. Smooth shell surface, ornamented only by delicate, slightly prosocline growth lines (visible only by magnification).

Remarks: The mesurements are not too different from that of Adeorbisina lateumbilicata (Uhlig, 1881), A. intermedia (Uhlig, 1881) and A. carinata (Uhlig, 1881) but they bear a peripheral carina that is lacking in A. nitens sp. n.. This difference makes an easy distinction possible. A. conica sp. n. and A. gibbosa (Conti & Fischer, 1981) has substantially different measurements and a prominent shell process at the abaxial deviation. The type species of Adeorbisina (A. canavarii Greco, 1889) is low lenticular and smaller than A. nitens sp. n.

Stratigraphical distribution: Condensed Niortense to Garantiana Zone.

Adeorbisina aff. nitens sp. n. (Pl. I : 9-12)

Material: a rather badly preserved shelly specimen. Measurements:

H HL HP W D A SL *14 *12.4 *10.2 •11.3 *21.5 120° 120°

Remarks: The available specimen is a little larger than A. nitens sp. n. and the preserved shell parts suggest a peripheral keel just at the weak abapical deviation (weaker than in A. nitens sp. n.). Other differences from A. nitens sp. n.: the whorls are not depressed, the base is rather convex and has no excavation but a heavy, large median callosity. The specimen probably represents another new species but the shell, imperfectly preserved at the abaxial deviation, does not make a reliable description possible.

Stratigraphical distribution: Condensed Niortense to Garantiana Zone.

STRATIGRAPHY, PALAEOBIOGEOGRAPHY, P A L A E O E C O L O G Y

Following the single Liassic (Late Pliensbachian - Toarcian) and Early Middle Jurassic (Aalenian) lineage, a Bajocian diversification is observable in Adeorbisina; four or five Bajocian and four ?Bathonian and/or ?Callovian species have been known.

No species of Adeorbisina were found out of the Mediterranean Province therefore the genus is a good "palaeobiogeographical index". Within the Mediterranean Province, the genus is widespread, known from the Eastern Carpathians (Klippen Belt; UHLIG 1878, 1881; ?Bathonian and/or ?Callovian; possibly Bajocian, mixed to Bathonian-Callovian ammonites), Bakony Mts. (SZABÓ 1981, CONTI & SZABÓ 1987; herein; Bajocian), Southern Alps (PARONA 1894; Bajocian), Umbria (CONTI & FISCHER 1981, CONTI & SZABÓ 1987; Bajocian), Calabria (GRECO 1899; Aalenian), Eastern Sicily (M. GEMMELLARO 1911; Upper Pliensbachian), Western Sicily (WENDT, 1971; condensed Aalenian to Lower Bajocian).

No reliable actualistic datum can be collected about the probable mode of life of Adeorbisina because the Colloniidae seems to be an extinct family (MONARI et. al. 1996). The shells of the Adeorbisina species are thick-walled, strongly built as that of the other members of the family (Colloniinae, Ataphrinae, Crossostomatinae). The development of this shell type may be the result of adaptation to highly agitated water and/or shell crushing prédation. In the Mediterranean Faunal Province, Adeorbisina (and other genera of the Colloniidae) were found only in facies, containing fossils from the most elevated biotopes where the substratum was probably hard

Members of the family, occurring also in "stable" European localities, are usually components of shallow water faunas but only a few data of detailed facies analysis are available: FISCHER (1969) reported highest frequency (but not high abundance) of Bathonian ataphrids and crossostomatids in slightly agitated upper infralittoral biotopes from the SW edge of the Massif Ardennais. However, the bottom in the studied paleoenvironment was, at least partly, unconsolidated. Therefore significant amount of sediment must have been suspended in the agitated water biotopes that makes these environments unfavourable for the Archaeogastropods (without Neritoidea and Patelloidea of traditional classifications). That may be the reason why members of the Colloniidae (and other archaeogastropods) appeared only in the "protected" and "calm" biotopes where the lowest amount of suspended sediment was present. In case of hard bottom and low rate of sedimentation, colloniids probably lived also in highly agitated (littoral and shallow infralittoral) water.

Though Adeorbisina is a rather diversified genus, its species are sporadic in the known gastropod assemblages

A C K N O W L E D G E M E N T

Preparation and publication of this paper was supported by the Hungarian Scientific Research Fund (OTKA T 4431).

R E F E R E N C E S

CONTI, M. A. & FISCHER, J.-C. (1981): Preliminary notes on the aalenian gastropods of Case Canepine (Umbria, Italy). - In: FARINACCI, A. & ELMI , S. (Eds.): Rosso Ammonitico Symposium Proceedings, Roma: 137-145.

FISCHER, J.-C. (1969): Géologie, Paléontologie et Paléoecologie du Bathonien au Sud-Quest du Massif Ardennais. - Mém. Mus. Natn. Hist. Nat, [n.s., C] 20: 1-319.

GEMMELLARO, M . (1911): Sui fossili degli strati a Terebratula Aspasia délia Rocche Rosse presso Galati (prov. di Messina). Cephalopodi (fine). - Gasteropodi. - Giorn. Sei. nat. econ. Palermo, 28 : 203-242.

GRECO, B. (1899): Fauna délie Zona con Lioceras opalinum Rein. sp. di Rossano in Calabria. - Paleontogr. Itai, 4: 93-139.

H l C K M A N , C. S. & MCLEAN, J. H. (1990): Systematic revision and suprageneric classification of trochacean gastropods. - Nat. Hist. Mus. of Los Angeles County, Los Angeles., [Science] 35: 1-169.

PARONA, C. F. (1894): La fauna fossile (Calloviana)di Acque Fredde sulla sponda Veronese del Lago di Garda. - Mem. R. Acc. Lincei, [4] 7: 364-396.

STOLICZKA, F. (1861): Über die Gastropoden und Acephalen der Hierlatz-Schichten. -Sber. Akad. Wiss. Wien. math.-naturw. CL, 43: 157-204.

SZABÓ, J., (1979): Lower and Middle Jurassic Gastropods from the Bakony Mountains (Hungary). Part I . Euomphalidae (Archaeogastropoda). - Annls. hist.-nat. Mus. natn. hung., 7 1 : 15-31.

S Z A B Ó , J., (1980): Lower and Middle Jurassic Gastropods from the Bakony Mountains (Hungary). Part I I . Pleurotomariacea and Fissurellacea (Archaeogastropoda). -Annls. hist.-nat. Mus. natn. hung., 72 : 49-71.

SZABÓ, J., (1981): Lower and Middle Jurassic Gastropods from the Bakony Mountains (Hungary). Part I I I . Patellacea and Trochacea (Archaeogastropoda). - Annls. hist.-nat. Mus. natn. hung., 73 : 55-67.

SZABÓ, J., (1982): Lower and Middle Jurassic Gastropods from the Bakony Mountains (Hungary). Part IV. Neritacea, Craspedostomatacea, Amberleyacea (Archaeo­gastropoda). -Annls. hist.-nat. Mus. natn. hung., 74: 17-33.

SZABÓ, J., (1983): Lower and Middle Jurassic Gastropods from the Bakony Mountains (Hungary). Part V. Supplement to Archaeogastropoda; Caenogastropoda. - Annls. hist.-nat. Mus. natn. hung., 75: 27-46.

CONTI, M. A. & SZABÓ, J: (1987): Comparison of Bajocian gastropod faunas from the Bakony Mts. (Hungary) and Umbria (Italy). - Annls. hist.-nat. Mus. natn. hung., 79: 43-59.

SZABÓ, J., CONTI, M.A. & MONARI, S. (1993): Jurassic gatropods from Sicily; new data to the classification of Ataphridae (Trochoidea) - Scripta Geologica, Special Issue 2: 406-416.

EXPLANATION TO P L A T E I.

1-4. Adeorbisina conica sp.n., holotype, M 96 351, x 1.5

5-8. Adeorbisina nitens sp. n., holotype, M 96 352, x 1.5

9-12. Adeorbisina ajf. nitens, M 96 353, x 1.5

MONARI, S., CONTI, M. A. & SZABÓ, J. (1996): Evolutionary systematics of Jurassic Trochoidea: the family Colloniidae and the subfamily Proconulinae. - In: TAYLOR, J. (Ed.): Origin and evolutionary radiation of the Mollusca., Oxford University Press, 199-204.

UHLIG, V. (1878): Beiträge zur Kentniss der Juraformation in den Karpatischen Klippen. - Jb. k. k. Geol. Reichsanst., 28: 641-658.

UHLIG, V. (1881): Über die Faune des rothen kellowaykalkes des penninischen Klippe Babierzówka bei Neumarkt in West-Galizien. - Jb. k. k. Geol. Reichsanst., 31: 381-422.

WENDT, J. (1971): Genese und Fauna submariner sedimentärer Spaltenfüllungen im Mediterranen Jura. - Palaeontographica, [A] 136:122-192.

Author's address: Dr. János SZABÓ Department of Geology and Paleontology Hungarian Natural History Museum H - 1341 Budapest P.O.B. 137 HUNGARY