Prionospio Malmgren, 1867
Prionospio? sp.
Voucher. Hero: Station 1MFA
Diagnosis. Voucher is the only specimen collected in this study. Incomplete, small and slender specimen 4mm long and 0.2mm wide for 23 chaetigers (of these last 6 are enlarged, swollen, without obvious segmentation, likely regenerating).
Prostomium anteriorly rounded, posteriorly extending to the end of chaetiger 1 as an elongated, slender caruncle; eyes absent. Peristomium partially fused to chaetiger 1, not pronounced into lateral wings. Branchiae missing in all chaetigers, but at chaetiger 2 a small, digitiform branchia was observed (on one side only). Notopodial and neuropodial lamellae are prominent, both narrow, elongated, protruding away from the body (rather than lying flat on the body), similar size in chaetigers 2-16, smaller in chaetiger 1, absent from chaetiger 17 until end of fragment (the swollen, regenerating region). All chaetae capillaries; sabre chaetae and hooded hooks absent in 23 chaetigers long fragment. Dorsal crests absent. Pygidium unknown.
Remarks. The presence of small branchial stumps (initially observed at least on chaetigers 2 and 3, but now lost due to damage during the examination), the shape of prostomium suggest this species may belong to genus Prionospio Malmgren, 1867. However absence of neuropodial hooks in 23 chaetigers is unusual in this genus (hooded hook normally start in chaetigers 10-20, see Paterson et al., 2015). The distribution and form of branchiae, an important diagnostic feature is also unknown in this specimen. While this species can be distinguished from the other spionid material from Falkland Islands by combination of shape of prostomium, podial lamellae and absence of any modified chaetae, its identity cannot be established based on currently available material.
