NEW OBSERVATIONS ON AMMOLAGENA CLAVATA () FROM THE MEDITERRANEAN SEA

One hundred and sixty specimens of Ammolagena clavata (Jones and Parker), encrusted on various bioclastic substrates, were collected from recent foredeep sediments of the Pontine Archipelago (Tyrrhenian Sea). Numerous specimens were measured, photographed, and analyzed, using energy dispersive spectrometry (EDS). The wall of A. clavata is composed of an agglutinated layer between two organic films. An EDS analysis showed high concentrations of Si and, subordinately, Al, both in the agglutinated and organic layers; the latter also contain high amounts of Fe. The presence of an incipient lip (pseudoseptum) at the beginning of the tubular chamber confirms the pseudo-bichambered architecture of the test. Its most problematic morphological feature is a second aperture at the base of the first chamber (proloculus). The variable morphology of the second pseudochamber is interpreted to be an adaptive behavior for avoiding occlusion of its aperture by the sediment. The presence of coccoliths and coccospheres within the chambers suggests that A. clavata is a suspension feeder. The upper limit of its bathymetric range in the Mediterranean Sea coincides with the upper limit of Mediterranean Levantine Intermediate Water.