Rhodine cf. intermedia Arwidsson, 1911  

Rhodininae Arwidsson, 1906

Rhodine Malmgren, 1865

Rhodine cf. intermedia Arwidsson, 1911

Vouchers. LOLIGO: station L11FA.

Diagnosis.  Medium-sized species, voucher incomplete; with 17 chaetigers-long in total fragmented into anterior fragment of 8 chaetigers (25mm long and 2mm wide) and additional 5 body fragments of varying lengths; colour in alcohol pale to yellow.

Prostomium (both specimens) without cephalic plaque, but with high cephalic keel; prostomium together with peristomium fused with first chaetiger, with a well-developed dorsal crest. First chaetiger long (much longer than wide); chaetiger 2 short (about as long as wide), rounded; chaetiger 3 long again, chaetigers short from chaetiger 4 until end of anterior fragments, rounded. Chaetigers 2 and 3 with well-developed segmental collar; anterior margin of collar, middorsally with a wide, very shallow depression; well-developed collars also observed on at least 3 other fragmented body segments (likely from mid or posterior part of the body).  From chaetiger 3-9 ventral glandular shields present on the anterior half of segment.                                                                                                                                                                   

Chaetigers 1-4 with notochaetae only; notochaetae comprise long and short narrowly-limbate capillaries. Uncini from chaetiger 5 arranged in double, interlocking rows, uncini in such arrangement until chaetiger 14, with about 48 uncini per row; from chaetiger 15 uncini arranged in single row. The uncini have a large main fang surmounted by several rows of small teeth; breast of uncini with a stout subrostral spine above basal prow; with medium length handle.                                                                                                                                        

Posterior part and pygidium not observed. Tube not observed.

Remarks.  Specimen is consistent with genus Rhodine in possessing collared segments, uncini from chaetiger 5, arranged in double rows on several anterior chaetigers. Rhodine is a small genus with some species considered to have a cosmopolitan distribution, the last description of new Rhodine species dates to 1911. Of Rhodine species previously reported from the region: R. antarctica, R. intermedia and R. loveni, the first two are considered endemic, but the third is cosmopolitan. The features separating the species (particularly R. intermedia and R. loveni) are not clear, but R. antarctica was described from small specimen, while the other two species are large bodied.  Falkland Island specimens are assigned here to R. cf. intermedia (see table below) (holotype of R. intermedia was collected in South Georgia) rather than to cosmopolitan R. loveni.  Further, characters derived from the posterior, particularly the form of pygidium cannot be established and chaetiger 2 is short not long in Falkland Island specimen (limitation of having only heavily fragmented specimens available needs to be taken into account). Other species belonging to this genus were also encountered in Falkland Islands collection and these are compared in the table below.

Comparison of Rhodine species reported from the region (as reported in literature) and Falkland Island specimens.