Sphaerodoridium minutum, paratypes USNM 22873, SEM. A Whole specimen, side view B Whole specimen, ventro-lateral view C Same, ventral view D Detail of stalked, dorsal macrotubercle E Dorsal macrotubercle and papilla F Anterior end, frontal view, showing head appendages and tubercles of anterior chaetigers G Mid-body parapodium, side view H Mid-body parapodia, anterior view I Posterior end and pygidium, ventral view J Chaetae anterior chaetigers K Chaetae mid-body parapodium L Detail of Mid-body chaeta. Abbreviations: al, acicular lobe; la, lateral antenna; ma, median antenna; mc, macrotubercle; mi, microtubercle; pa, palp; tc, tentacular cirrus; vc, ventral cirrus.