2 literature references for Hemigellius arcofer (Vosmaer, 1885):

Author: Vosmaer, G.C.J.
Year: 1885
Title: The Sponges of the ‘Willem Barents’Expedition 1880 and 1881.
Source: Bijdragen tot de Dierkunde 12(3): 1-47,pls I-V.
Author: de Weerdt, W.H.; van Soest, R.W.M.
Year: 1987
Title: A review of north-eastern Atlantic Hemigellius (Niphatidae, Haplosclerida)
Source: in: Vacelet, J. Boury-Esnault, N. (Ed.) (1987). Taxonomy of Porifera from the N.E. Atlantic and Mediterranean Sea. NATO ASI Series G: Ecological sciences, 13: