Paradoneis Hartman, 1965
Paradoneis sp. 1
Voucher specimen. Vinson West: Station 1MFA.
Diagnosis. Small sized, very slender species; voucher is the largest with 43 segments (incomplete specimen), 6mm long and 0.3mm wide; body of uniform width throughout, segments becoming bead-like in middle and posterior segments; colour in alcohol pale yellow.
Prostomium triangular, slightly longer than wide, anteriorly blunt; prostomial antenna absent; nuchal organs present as two short slits in posterior part of prostomium.
Branchiae from chaetiger 4, 5 pairs in voucher specimens (as few as 2 pairs in other specimens), the last pair short (not meeting at midline), the middle branchiae long (overlapping at midline), all with blunt tips.
Notopodial postchaetal lobes in prebranchial segments small digitiform, smallest in chaetiger 1 then lengthening progressively becoming largest in branchial region with their bases slightly inflated, slender, cirriform in postbranchial region.
Notochaetae long capillaries, most dense in the anterior part of the body. Modified chaetae lyrate (forked) from chaetiger 6 (very difficult to observe as notochaetae very dense), becoming easy to observe from around chaetiger 9, only one per fascicle, with unequal tines, with long filamentous tips, both tines with inner edges serrated. Neurochaetae capillaries only, most dense in anterior part of the body. Pygidium not observed.
Remarks. Only P. brunnea Hartmann-Schröder and Rosenfeldt, 1988 is a known Paradoneis species from the area (Southern Ocean), possessing three prebranchial chaetigers, short blunt form of branchiae, presence of modified lyrate chaetae only (i.e. no spines) in notopodia. However there are also differences in that FI specimens lack the brown pigmentation of P. brunnea, lyrate chaetae occur from chaetiger 6 (rather than 3 in P. brunnea) and possess a much smaller number of branchiae (5 observed versus 12 in P. brunnea).
P. forticirrata described by Strelzov (1973) from the deep Pacific Ocean in which first lyrate spines also occur in segment 4-6, but differs in possessing 15-17 pairs of branchiae and most importantly Strelzov described the notopodial postchaetal lobes on prebranchial segments as massive and made this important distinguishing character from other species of Paradoneis (Strelzov 1973, p.147). However, the accompanying drawing in Strelzov (p. 146) does not show large notopodial lobes. These are in fact similar to those found in FI specimens and also described in P. brunnea. A comparative table for known species of Paradoneis was provided by Aguirrezabalaga and Gil (2009). However, characters such as the number of branchial pairs is variable (probably size dependent) and so we cannot exclude the possibility that, given the small size of FI specimens, they are in fact juveniles of one of these species. Additional work will be necessary to confirm if FI specimens in fact represent a new species or merely a juvenile form.
