Re-description of two marine sponge species (Demospongiae: Haplosclerida) from the coast of Karachi, Pakistan, Northern Arabian Sea

Marine sponges are a highly diversified group of invertebrates (phylum Porifera) which inhabit different substrates in the coastal regions of the world. These sponges play an important role in the food web and provide a protected and nutrient-rich habitat for a variety of organisms. This is the first report on the re-description of two marine sponges belonging to the class Demospongiae, order Haplosclerida inhabiting the coastal waters of Karachi (Pakistan; Northern Arabian Sea). Callyspongia (Cladochalina) fibrosa (Ridley and Dendy, 1886) (Family Callyspongiidae) was collected from Churna Island at 7 m depth through SCUBA diving and Haliclona (Soestella) hornelli (Dendy, 1916) (Family Chalinidae) was collected from the rock pools of Buleji rocky ledge. The skeletal framework of both sponges was observed in light and scanning electron microscope. The spicules of C. (C.) fibrosa were smooth and densely packed with thick ectosomal and choanosomal fibres. The choanosomal skeleton of H. (S.) hornelli was sub-anisotropic, forming a reticulation of meshes with unispicular and paucispicular lines, and its spicules were slender megascleres while microscleres absent. H. (S.) hornelli is assigned to the subgenus Soestella of the genus Haliclona.