A new species of Echinoderes is described from the Chuuk Islands, Micronesia. Echinoderes inaequalis sp. nov. clearly belongs to the Echinoderes coulli species group due to the presence of enlarged sieve plates, reduced trunk spines (excluding the terminal series) and a hairy habitus. E. inaequalis sp. nov. is characterised by the presence of a minute middorsal spine on segment 4; unpaired subdorsal tubes in alternating positions on segments 5–7; lateroventral tubes on segments 5, 7–9, midlateral tubes on segment 8, sexually dimorphic laterodorsal tubes on segment 10; numerous glandular cell outlets type 2 located on segments 2, 4–8; and very short and stout terminal spines (ca. 12% of the trunk length). The subdorsal unpaired tubes of segments 5–7 show intraspecific variation. E. inaequalis sp. nov. increases the count of the E. coulli group to 23 species.