FIGURE 1. Study area and sampling operation. A in Manned submersible dives reveal a singular assemblage of Hexactinellida (Porifera) off the Amazon River mouth, Northern Brazil

FIGURE 1. Study area and sampling operation. A, map of South America and Brazil depicting the study area (rectangle); B, insert depicting the Amazon River mouth region with the two manned submersible diving stations where hexactinellids were sampled: one dive included sites 1–3, off Pará State and the other included site 4, off Maranhão State. Site 1—Claviscopulia facunda, site 2—Dactylocalyx pumiceus (white morphotype), site 3—Hyalonema (Cyliconemaoida) alucia sp. nov., site 4—aggregation of Dactylocalyx pumiceus (cream morphotype); C, MV Alucia launching the manned submersible Deep Rover; D, sampling of Hyalonema (Cyliconemaoida) alucia sp. nov. using the submersible's mechanical arm. C-D, photographs by F. Moraes.