Five new species of Homoscleromorpha (Porifera) from the Caribbean Sea and re-description ofPlakina jamaicensis

Abstract

Five new species of Homoscleromorpha (Porifera) of four genera,Oscarella,Plakortis,PlakinaandCorticium, are described from vertical walls of reef caves at depths ranging from 23 to 28 m in the Caribbean Sea.Oscarella nathaliaesp. nov. has a leaf-like thinly encrusting, flat body, loosely attached to the substrate and a perforated, not lobate surface.Oscarella nathaliaesp. nov. contains two bacterial morphotypes and is characterized by two mesohylar cell types with inclusions.Plakortis myraesp. nov. has diods of two categories: abundant large ones (83–119 μm long) and rare small ones (67–71 μm long) with sinuous, S-bent centres; triods Y- or T-shaped (18–5 μm long), and abundant microrhabds (5–12 μm long).Plakortis edwardsisp. nov. has diods of one category with thick, sinuous, S-bent centres (110 to 128 μm long); triods T-shaped (actines 28–59 μm long). It is the only species of this genus showing small diods (22–31 μm long).Plakortis dariaesp. nov. has diods of two categories: large ones (67–112 μm long) and small, rare, irregular ones, slightly curved, often deformed with one end blunt (30–59 μm long); triods rare and regular (actines 20–44 μm long).Corticium diamantensesp. nov. has oscula situated near its border, regular non-lophose calthrops of one size-class, very rare tetralophose calthrops and candelabra with the fourth actine ramified basally in 4–5 microspined rays. In addition, a re-description ofPlakina jamaicensisis based on newly collected material and the type specimen.Plakortis jamaicensishas a convoluted brain-like surface; well developed sub-ectosomal cavities; irregular sinuous diods, triods, calthrops, rare monolophose calthrops, rare dilophose calthrops, rare trilophose calthrops and common tetralophose calthrops. Molecular ‘barcoding’ sequences for mitochondrial cob are given forPlakortis edwardsisp. nov.,P. dariaesp. nov.,Plakina jamaicensisandCorticium diamantensesp. nov. An identification key for all western Atlantic Homoscleromorpha is provided.