Study of the morphological affinity between two species of benthic foraminifera from restricted environments: Rosalina douvillei (Cushman, 1928) and Trichohyalus aguayoi (Bermúdez, 1935)

Abstract

A biometric comparison is carried out on selected tests of the foraminiferal species Rosalina douvillei (Cushman, 1928) and Trichohyalus aguayoi (Bermudez, 1935). The Rosalina douvillei specimens were recovered from the marginal marine Oligocene/Miocene site of Russingen (Mainz Basin, Germany), the lacustrine beds of the lower Miocene site of Bunol (Valencian Community, Spain) and the middle/ upper Miocene site of Fuendetodos (Aragon, Spain). The Trichohyalus aguayoi tests were collected in the current coastal lagoon of Torreblanca and recovered from Holocene cores sampled in the Peniscola marsh and in the coastal lagoon of l’Albufera de Valencia, all them in the Valencian Community (Spain). In addition, the chronostratigraphic and geographical distribution of both species is also summarized. Trichohyalus aguayoi and Rosalina douvillei share many morphological characteristics but the measured specimens of Trichohyalus aguayoi are characterized by generally larger sizes, narrower and more elongate chambers and a higher number of chambers in the outer whorl. The Rosalina douvillei specimens from Fuendetodos are as large as Trichohyalus aguayoi and show particularly high chamber size increase rates but also few and less elongate chambers in the last whorl. The number and shape of chambers in the last whorl seem thus to be controlled at least in part by hereditary factors. The morphological affinity between the two species probably constitute an example of convergence derived from similar environmental conditions but further research is required to discard phylogenetic proximity.