Nuevos datos para la determinación sistemática de Rhapidothyris delorenzoi (Böse, 1900): un Loboidothyridoidea (Brachiopoda) del Jurásico Inferior mediterráneo

Abstract

Se discute la atribución sistemática de Terebratula delorenzoi (Böse, 1900) dentro del género Rhapidothyris Tuluweit, 1965, a la luz de los resultados obtenidos a partir del estudio de su morfología interna, la cual se muestra por primera vez, conjuntamente con un análisis poblacional de sus rasgos externos más significativos, formalizando así su precisa caracterización. Se discuten además las afinidades y diferencias de R. delorenzoi con otras especies próximas y se concreta su distribución estratigráfica en el Jurásico Inferior dentro del dominio Subbético, en relación con su registro en las localidades estudiadas. Los datos obtenidos en la cuenca subbética ponen de manifiesto la presencia del género Rhapidothyris en los sectores más suroccidentales del Tethys, cuyas primeras atribuciones fueron realizadas en provincias paleobiogeográficas de carácter subboreal.

The systematic allocation for Terebratula delorenzoi (Böse, 1900) within the genus Rhapidothyris Tuluweit, 1965 is discussed, based on a comprehensive population analysis of their most significant external features and on the study of their internal anatomical structure, which have been characterized by the first time in the present work, formalizing its precise characterization. The main diagnostic features of Rhapidothyris delorenzoi distinguish it from similar species belonging to Linguithyris or Viallithyris genus or even of conspecific taxa as R. reversa or R. tendinea. These features are the rounded outline of the shell, its anterior commissure intraplicate and lack of ornamentation; the hinge plates narrow and arched, with strong ventral concavity, a crown-shaped cardinal process highly striated and the crural bases extremely thin. Rhapidothyris. delorenzoi is recorded at several localities located in the fundamentally calcareous Jurassic outcrops situated in the southern area of the province of Alicante and the northern zone of Murcia (SE Spain), belonging to the most easterly area of the External Zone of the Betic Cordillera. On the basis of these findings is inferred that the distribution range of R. delorenzoi can be established between Lavinianum Zone and the lowermost Polymorphum Zone. This age coincides with the records made by other authors in classical tethysic basins next to the Subbetic Domain. Through the records found in the Eastern Subbetic and updating some specimens housed in historical collections from the same area (Jiménez de Cisneros Collection), it is evidenced the presence of this species in the Southwestern Tethys areas, in addition to the few records known until now, in Hungary and Italy.