Pareurythoe Gustafson, 1930

Pareurythoe Gustafson, 1930 View in CoL , restricted

Pareurythoe Gustafson, 1930: 309 View in CoL (species list), 319, 391–393 (diagnosis); Hartman 1940: 203 (composition); Hartman 1948: 45 (type species: P. californica ( Johnson, 1897)) View in CoL ; Hartman, 1959: 137 (type species: P. japonica Gustafson, 1930 View in CoL ); Fauchald 1977: 102 (diagn.); Bleeker et al. 2023: 438 (key).

Type species. Pareurythoe japonica Gustafson, 1930 View in CoL (by subsequent designation, Hartman 1959: 137).

Diagnosis (modified from Fauchald, 1977: 102; modifications in bold type). Amphinominae with body with parallel sides, usually abruptly tapered anteriorly and posteriorly; caruncle narrow, without lateral lobes, reaching chaetigers 1–3, longer than median antenna; branchiae dendritically branched present along body from chaetiger 2–3; parapodial cirri smooth.

Remarks. Among Amphinomin genera, Pareurythoe is very similar to Cryptonome because both have chaetiger 1 dorsally incomplete, a small caruncle, and branchiae along most body chaetigers. However, there are two consistent differences between them. In Pareurythoe the median antenna is shorter than the caruncle, and first branchiae have a few filaments, whereas in Cryptonome the median antenna is as long as, or longer than caruncle, and first branchiae have many filaments. Another interesting difference is ecological, because the species of Pareurythoe have been found in sediments, whereas most Cryptonome species have been found in decaying wood.

Composition. Besides the type species, P. japonica Gustafson, 1930 , the genus includes five other species: P. borealis ( Sars, 1862) from Norway, P. californica ( Johnson, 1897) from California, P. chilensis ( Kinberg, 1857) from Chile, P. gracilis Gustafson, 1930 apparently based upon specimens from the Marshall and Gilbert Islands, and P. pitipanaensis de Silva, 1965 from Sri Lanka. Hartman (1968: 201) transferred Eurythoe spirocirrata Essenberg, 1917 to Pareurythoe , but the study of the type specimen allowed us to return it to Eurythoe (see below)

On the other hand, P. parvecarunculata ( Horst, 1912) from Malaysia was transferred to the genus by Imajima (2003), and regarded as belonging in Cryptonome by Borda, Kudenov, Bienhold & Rouse (2012, see above).