Dysponetus, Levinsen, 1879

Darbyshire, Teresa, 2012, Re-description of Dysponetus joeli Olivier et al., 2012 (Polychaeta, Chrysopetalidae), with a new key to species of the genus, European Journal of Taxonomy 27, pp. 1-9 : 6-7

Key to Dysponetus species

1 Ventral tentacular cirri absent on segment 1 ………………………………………………………2 – Ventral tentacular cirri present on segment 1 ………………………………………………………6

2 Elongate palps; 4 eyes …………………………………… D. bulbosus* Hartmann-Schröder, 1982 – Sphaerical palps; 2 eyes or eyes absent ……………………………………………………………3

3 Anterior median antenna; double mouth appendage on lower lip; 2 eyes ………………………… ……………………………………………………………… D. hebes ( Webster & Benedict, 1887)

– Dorsal median antenna; eyes absent ………………………………………………………………4

4 Ventral tentacular cirri present on segment 2 ………………………… D. gracilis Hartman, 1965 – Ventral tentacular cirri absent on segment 2 ………………………………………………………5 5 Mouth appendage absent; paleae present among notochaetae …………………………………… ………………………………………………………… D. paleophorus Hartmann-Schröder, 1974

– Double mouth appendage on lower lip; paleae absent …………… D. pygmaeus Levinsen, 1879

6 Mouth appendage absent …………………………………………………………………………7 – Single mouth appendage on lower lip ……………………………………………………………8

7 Elongate palps, ventral tentacular cirri present on segment 2 …… D. hesionides Böggemann, 2009 – Sphaerical palps, ventral tentacular cirri absent on segment 2 …… D. profundus Böggemann, 2009

8 Eyes absent, ventral cirri present on segment 3 …………………… D. caecus ( Langerhans, 1880) – Eyes present, ventral cirri absent on segment 3 …………………………………………………9

9 16 or less notochaetae in mid-body segments ………… D. bulbosus* Hartmann-Schröder, 1982 – 20 or more notochaetae in mid-body segments …………………………………………………10

10 Ventral tentacular cirri absent on segment 2 …………………………… D. bidentatus Day, 1954 – Ventral tentacular cirri present on segment 2 ……………………………………………………11

11 Few neurochaetae, only 9–13 in mid-body segments …………… D. bipapillatus Dahlgren, 1996 – Numerous neurochaetae in mid-body segments, 19 or more …………………………………12

12 Small body size, 2–3 mm; 19–22 neurochaetae ………………… D. macroculatus Dahlgren, 1996 – Large body size,> 3 mm; 20–26 neurochaetae …………………… D. Joeli Olivier et al., 2012

* Descriptions of D. bulbosus ( Hartmann-Schröder 1982, 1986) contradict each other over the presence or absence of ventral cirri on each of the first few segments. For this reason, D. bulbosus is included twice in the key to account for the discrepancy in descriptions. Dysponetus bulbosus will be reviewed in a forthcoming paper.