Chaetoderma attenuatum Heath, 1911: 43, 55–59; pl. 4, figs. 3, 10; pl. 5, fig. 1; pl. 12, fig. 4; pl. 25, figs. 1–10; pl. 36, fig. 2; pl. 37, fig. 8.
Current taxonomic status. Synonym of Chaetoderma argenteum Heath, 1911.
Type locality. vicinity of Prince Wales Island (~ 56 42’N, 132 25’W), Alexander Archipelago, Southeast Alaska, USA, 61–66 fathoms (87–94 m).
Type material. Paratypes MCZ 302673 (1 spm + 5 slides), MCZ 302674 (2 spms), MCZ 302675 (2 spms + 23 slides).
Remarks. Heath (1911) originally described C. attenuatum based on samples from ‘Albatross stations’ 4244, 4250 and 4252. Two individuals from station 4250 are mixed with the single specimen from station 4244, and together they form the lot MCZ 302675. Originally, five specimens were obtained from station 4250 (Heath 1911), and the two remaining animals from this station are in MCZ 302674. The two specimens from station 4252 correspond to MCZ 302673. The holotype is in the California Academy of Sciences, San Francisco, USA (CAS 21393) as slides with serial sections and spicules prepared from one of the specimens from station 4250 [it is listed as ‘CAS 191’ in Stasek (1966)]; however, Salvini-Plawen (1993) argued that Heath “obviously confused or mixed up” the material he examined, and that this specimen is actually an individual of C. montereyense. This species is currently accepted as a synonym of C. argenteum Heath, 1911, a matter which was initially proposed by Scheltema et al. (1991), and followed by Salvini-Plawen (1993) and Scheltema (1998).