Large dendrinids meet giant clam: the bioerosion trace fossil Neodendrina carnelia igen. et isp. n. in a Tridacna shell from Pleistocene–Holocene coral reef deposits, Red Sea, Egypt

Abstract. The rosette-shaped microboring trace fossil Neodendrina carnelia igen. et isp. n. – a large representative of the ichnofamily Dendrinidae – is identified on the inner side of the giant clam Tridacna maxima from Pleistocene to Holocene coral reef deposits of the El Quseir district at the Egyptian Red Sea coast. The new dendritic bioerosion trace fossil is diagnosed as a radial rosette comprised of a prostrate system of roofless canals that ramify in a strictly dichotomous fashion forming intermittent branches of uniform width and rounded terminations. The trace appears to be rare, although in the type material it occurs in a cluster of more than a hundred specimens. The location of traces on the interior surface of the shell suggests that boring occurred post-mortem to the host. Its record is presently restricted to shallow marine, euphotic, tropical coral reef settings in the Western Indo-Pacific (Red Sea and Madagascar). The biological identity of the trace maker cannot be resolved yet, but several lines of reasoning allow speculations directed towards a complex attachment scar, perhaps produced by a benthic foraminiferan or a macrophyte.