Original paper

Ostrakoden aus dem Rollsteinkalk (= Macrouruskalk, unteres Ober-Ordoviz)

[Ostracodes from the Rollsteinkalk (= Macrourus limestone, lower Upper Ordovician)]

Schallreuter, Roger; Hinz-Schallreuter, Ingelore

Kurzfassung

Es wird erstmals eine Synopsis aller bisher aus dem Rollsteinkalk (= Macrouruskalk) beschriebenen/erwähnten Ostrakoden gegeben. Die bisherigen Daten sind in der Literatur sehr verstreut. Bei den Rollsteinkalken handelt es sich um Mergelkalke, die mit Hilfe von Flusssäure aufbereitet werden können. Mit Hilfe der Ostrakodenfaunen können zwei altersmäßig verschiedene Typen unterschieden werden: die vor allem durch Sigmoopsis rostrata (Krause 1892) gekennzeichneten, der Keila-Stufe (D2) Estlands entsprechenden, älteren Macrouruskalke, und die durch Sigmoopsis granulata (Sarv 1956) charakterisierten, jüngeren Macrouruskalke, die gleichalt mit der Oandu-Stufe (D3) Estlands sind. Die Ostrakodenfaunen unterscheiden sich sehr stark voneinander, nur wenige Arten, v. a. Pentagona oanduensis und Lembitites posterovelatus, kommen in beiden Typen vor. Nach Unterarten von Tetrada krausei lassen sich bei den älteren Macrouruskalken vermutlich mehrere Untertypen unterscheiden, die möglicherweise auf verschiedene, im Bereich der Ostsee liegende oder nicht mehr existierende Herkunftsgebiete hinweisen. Es wurden über 60 Arten gefunden. Neu sind: Tetrada (Neotsitrella) pseudoperita sp. n., Circulinella latogutta sp. n., Disulcinoides sinecristata sp. n., Bulbosclerites? ponos sp. n. und Brevichoides biumbones sp. n. Einige bisher nur aus dem Anstehenden bekannte Arten werden erstmals aus Geschieben bekannt gemacht: Ectoprimitia inconstans Meidla, 1996, Bolbihithis superus Sidaravičienė, 1992, Hemiaechminoides minusculus Meidla, 1986, Hemeaschmidtella witoldi Sztejn, 1989, Krauselloides peregrinus Meidla, 1996.

Abstract

Descriptions and mentionings of certain ostracode species are scattered in the literature about Rollsteinkalk (= Macrourus limestone). Therefore, a synopsis of the ostracode fauna of the respective geschiebes (glacial erratic boulders) is presented. The Rollsteinkalk is a more less marly limestone, of which calcareous microfossils can be extracted by hydrofluoric acid. Based on ostracodes, two main types of Macrourus limestone – besides of various subtypes – are distinguishable: the older Macrourus limestone, which corresponds to the Keila stage (D2) of Estonia, and the younger Macrourus limestone, which is contemporaneous with the Oandu stage (D3) of Estonia. The ostracode faunas of the two types are distinctly different, only few species do occur in both types, mainly Pentagona oanduensis and Lembitites posterovelatus. Based on different subspecies of Tetrada krausei within the older Macrourus linestone possibly several subtypes can be distinguished presumably originating from different regions in the Baltic Sea or from today completely eroded deposits. Taxonomic results: More than 60 species have been found. New are: Tetrada (Neotsitrella) pseudoperita sp. n., Disulcinoides sinecristata sp. n., Circulinella latogutta sp. n., Bulbosclerites? ponos sp. n., and Brevichoides biumbones sp. n. The following synonyms have been recognized: Primitiella magna Sarv, 1956 = ?Platybolbina temperata Sarv, 1956, Pentagona veloreducta Schallreuter, 1967 = Haploprimitia oanduensis Sarv, 1956, Uhakiella rete Schallreuter, 1971 = Sigmobolbina quanta reticulata Sarv, 1959, Braderupia pozdziechi Schallreuter, 1993 = Pseudostrepula pseudoacuta Sidaravičienė, 1992, Unisulcopleura? molli altior Schallreuter, 1993 = Tior carina (Sidaravičienė, 1992), Tvaerenella stossmeisteri Schallreuter, 1985 = Oepikella canaliculata (Krause, 1892) = O. tvaerensis Thorslund, 1940 = O. asklundi Thorslund, 1940. Bolbina latimarginata (Bonnema 1909) is considered to be synonymous to B. ornata (Krause 1897). The smaller females of B. latimarginata are not preadults; the differences in size are the result of phylogenetic increase in size within one species. The holotypes of Entomis oblonga Steusloff, 1895 (= Vittella? oblonga) and Beyrichia krausei Steusloff, 1895 are refigured. Tetrada krausei is an older synonym of T. iewica (Neckaja 1953), T. troppenzorum Schallreuter, 1988, and of T. pseudoiewica Sidaravičienė, 1992 but T. iewica and T. troppenzorum remain valid as subspecies of T. krausei. The species Bolbina rakverensis Sarv, 1956 and B. major (Krause 1892) which were considered as synonyms by Schallreuter (1985) are cryptic species in respect of their tecnomorphs. The females are distinguished by their domiciliar dimorphism. The holotype of B. rakverensis is a tecnomorph and the possibility exists that it belongs to B. major indeed and both nominal species, which may occur together are synonyms. If this were the case, the specimens described as B. rakverensis by most authors would in fact represent a new species. The assumed synonymy of Disulcinoides longocristatus Schallreuter, 1982 with Diculcina perita Sarv, 1959 is confirmed. D. wachsae Schallreuter, 1988 is considered as a subspecies of D. perita. The type-species of Easchmidtella Schallreuter, 1967, E. crassiumbonata Schallreuter, 1967 is considered as a synonym of Schmidtella fragosa Neckaja in Abushik et al., 1960. However, both taxa maintain the status of own subspecies. The designation of Bubnoffiopsis incognitus to Lembitites is rejected. Contrary to Sarv (1956, 1959) and Meidla (1996), Leperditella prima is not considered as a representative of the genus Leperditella. Presently, Leperditella is a “sack genus”. The type-species has quite another outline (“leperditellid”) and is probably characterized by domiciliar dimorphism as documented in a species by Copeland (1974). The latter species is possibly identical with the type-species as presumed by the author already in 1984 and later also by Lundin, William & Siveter (1995).

Keywords

OstrakodenRollsteinkalkMacrouruskalkOber-OrdovizOstracodesMacrourus limestonelower Upper Ordovician