Osservazioni su Raadshoovenia Van Den Bold e i suoi rapporti col nuovo genere Scandonea (Foraminiferida, Miliolacea)

  • Nei sedimenti neritiei del Cretacico superiore dell'Appennino sono presenli dei miliolidi planispirali, involuti, spesso provvisti di stadio svolto. con apertura cribrata ed endoscheletro costituito, nelle logge adulte, da strato basale e da lame. Questi caratteri sono quelli che fino ad ora caratterizzavano il genere Raadshoovenia VAN DEN BOLD. Allo scopo di accertare fino a che punto le forme da me riscontrate differissero da quelle' guatemalteche ho esaminato alcuni esemplari di Raadshoovenia guatemalensis raccolti da VAN DEN BOLD. In essi ho potuto riscontrare dci caratteri interni più complessi di quelli che figurano nella diagnosi generica; questi sono costituiti, nelle logge adulte, oltre che da lame anche da strato basale e da pilastri che, lateralmente, si saldano tra loro e con le lame determinando camerette centrali e marginali. Si è reso perciò opportuno l'emendamento del genere Raadshoovenia e della sua specie tipo R. guatemalellsis. In base alla diagnosi emendata risultano sinonimi del genere di VAN DEN BOLD Cuvillierinella (PAPETTI e TEDESCHI, 1965) e Murciella (FOURCADE, 1966). Le forme da me rinvenute nell'Appennino e che soddisfano alla vecchia diagnosi di Raaclshoovenia sono state attribuite a Scandonea n. gen. la cui specie tipo è Scandonea samnitica n. sp. Si è proposta, inoltre, una diagnosi più comprensiva per ]a famiglia Alveolinidae al fine di poter inserire in essa il genere di VAN DEN BOLD. In questo lavoro ho accennato, in un apposito paragrafo, alla nomenclatura adottata. In particolare, le misure di altezza sono espresse da segmenti perpendicolari all'asse di avvolgimento o all'andamento della spira; per questo motivo altezza del guseio o dei giri sono sinonimi di diametro del guscio e diametro dei giri. Le misure di larghezza sono espresse da segmenti paralleli all'asse di avvolgimento; quelle di lunghezza vengono eseguite parallelamente all'andamento della spira.
  • In neritic sediments of upper Cretaceous of Apennines it is possibile to find planispiral miliolids, involute, very often with uncoiled stage, with cribrate aperture and endoskeleton constituted, in the adult chambers, by basal layer and subepidermal partitions. These characters are the ones that so far had characterized the genus Raadshoovenia VAN DEN BOLD. In order to ascertain up to which point the forms I have found are different from those found in Guatemala, I have examined some specimens of Raadshoovenia guatemalensis picked up by VAN DEN BOLD. It has been possible for me to notice some internal characters more complex than those appearing in generical diagnosis; these are constituted, in tlIe adult chambers, in addition to subepidermal partitions also by pillars that, laterally, are joined one another as well as with subepidermal partitions, thus giving rise to centrai and marginal chamberlets. Therefore it has been useful to emend the genus Raadshoovenia along with its type species R. guatemalensis. As a consequenee of the emended diagnosis, Cuvillierinella (PAPETTI & TEDESCHI, 1965) and Murciella (FOURCADE, 1966) are synonymous of Raadshoovenia. The forms I have found in the Apennines alld that were compatible with the old diagnosis ol Raadshoovenia have been attributed to Scandonea n. gen. whose type species is Scandonea samnitica n. sp. As far as we know at the present moment, I think it is possible to recognize the validity of the following genera characterized by the similar internal structure: - Sellialveolina, completely coiled and missing final flabelliform stage. - Pseudedomia and Chubbina, probably derived from Sellialveolina, with chambers with a flabelliform arrangement in the last stage. - Raadshoovenia, most likely derived from Scandonea, characterized by an uncoiled cilindrical or subcilindrical stage. The reference to the rank of family of the above mentioned genera is not far from doubt. Howerer, structural anologies that genera present with aiveolinids push me to assume, as it has been indicated by others, that the former have to be grouped together with the latter. So that reference he correct, the diagnosis of the family Alveolinidae should be enlarged to embrace: « test calcareous, imperforate, porcelaneous, planispirally coiled or with a marked tendency to become planispiral ; an uncoiled stage may be present in the adult. B farm with initial milioline coiling; A form with proloculus followed bay a flexostyle canal. At least in the adult stage the chambers are internally subdivided into chamberlets that are spirally arranged and comunicate among themselves, in the inner and anterior part of a chamber, by means of a preseptal space. The latter, if more developped linearly and in coiling axial way, specializes itself in a preseptal canal. In this work I have mentioned, in a speciai paragraph, the adopted nomenclature. More specifically, height measures are expressed by segments perpendicular to axis of coiling or spirai patterns; for this reason height of the test or of the whorls are synonimous with diameter of the test and diameter or the whorls. Measures of width are expressed by segments parallel to the axis of coiling; measures of length are taken on lines parallel to spiral patterns.

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Author:Piero De Castro
Parent Title (Italian):Bollettino della Società dei Naturalisti in Napoli
Document Type:Article
Date of Publication (online):2009/12/17
Year of first Publication:1971
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2009/12/17
Page Number:109
First Page:161
Last Page:235
Signatur: 8 Q 17.127
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 56 Fossilien, Paläontologie / 560 Paläontologie; Paläozoologie
Sammlungen:Sammlung Biologie / Weitere biologische Literatur (eingeschränkter Zugriff)
Licence (German):License LogoArchivex. zur Lesesaalplatznutzung § 52b UrhG