Asclerocheilus Ashworth, 1901
Asclerocheilus sp. 1
Voucher: SEA LION: station 19MFA.
Diagnosis. A small-sized species, body elongate, arenicoliform, expanded in anterior half then tapering in abdominal region; voucher specimen incomplete with 27 chaetigers, fragment 5mm long and 0.5mm wide at its widest. Colour in alcohol tanned. Body segments triannulate; annulations formed of small squared cells; annulation distinct. Pygidium missing.
Prostomium small, with prominent rounded anterolateral horns giving it overall heart-shaped appearance; posterior margin of prostomium visible dorsally; eyes absent. Peristomium achaetous, not concealing posterior margin of prostomium, consisting of single ring complete dorsally.
Branchiae absent. Parapodia biramous, reduced, inconspicuous throughout. Dorsal and ventral cirri not developed.
All chaetigers with noto- and neuropodial fascicles of slender capillaries. Chaetiger 1 and 2 with a row of about 10 large, heavy, slightly curved spines, with long filamentous tips. Lyrate chaetae present from chaetiger 2; tines unequal, the longer tine with long slender filamentous tip with distinct subdistal kink.
Remarks. The combination of the following characters – arenicoliform body shape, shape of prostomium, presence of large spines, absence of branchiae and absence of dorsal and ventral cirri make this specimen consistent with genus Asclerocheilus (see Blake, 1981). This genus is represented in the region by only two known species Asclerocheilus capensis Day, 1963 and A. ashworthi Blake, 1981. Falkland Island specimen differs from this species in having distinct rounded prostomial lobes. Such lobes are also present in South African species A. capensis, but Falkland specimen differs in having a heart-shaped prostomium (posteriorly narrower than anteriorly) and lyrate chaetae possess a distinct subdistal kink of the longer tine. Falkland Islands specimen likely represents a new species.
