Laonice Malmgren, 1867
Laonice sp. 1
Voucher specimens. Sea Lion: Station 26MFC, Station 35MFC, Station 38MFA, Station 52MFA.
Diagnosis. Voucher is the largest specimen; incomplete, an anterior fragment 37mm long, 4mm wide for 42 chaetigers. Anterior part of body enlarged and flattened; colour in alcohol off white to yellow.
Prostomium narrow, anteriorly rounded; indistinctly fused with peristomium by a thin membrane (peristomial lateral wings not rising above prostomium); eyes absent or present as only one pair of small red eyes; occipital antenna present, rudimentary, cirriform; caruncle long, continuing posteriorly to chaetiger 15. Palps not observed.
Branchiae from chaetiger 2; small, cirriform at first increasing in length and thickness in subsequent segments; fused to notopodial postchaetal lamella basally; exact number of branchiae impossible to define, since all the specimens are incomplete.
Chaetiger 1 slightly shorter than chaetiger 2, with triangular, short notopodial postchaetal lamellae and rounded neuropodial lamellae; postchaetal lamellae of following chaetigers increasingly larger, triangular and acutely pointed in notopodia, rounded in neuropodia.
Dorsal crests not observed. Neuropodial pouches present; first occurrence varies from segment 6-10, most commonly appearing from segment 7; initially these may be small and translucent (can be easily overlooked) developing into obvious fleshy pouches by segment 10.
Capillaries narrowly limbate, with fine granules imbedded in shaft arranged in two rows in both notopodia and neuropodia throughout. Sabre chaetae, granulated throughout most of its length, present form chaetiger 15, 1-3 per fascicle. Neuropodial hooded hooks present from chaetigers 27 - 31; 8 -10 per fascicle; hooks bidentate (in lateral view) with main fang surmounted by a smaller apical tooth; shaft stout and finely striated.
Pygidium missing in all specimens studied.
Remarks. This species was very abundant in samples from FI, but its superficial similarity to widespread Southern Ocean species Laonice weddellia in the shape of prostomium and start of genital pouches which might have led to misidentification of this species previously. In fact the presence of Laonice weddellia has not been confirmed in the FI material so far, but it has been recorded by previous faunistic studies (Blake, 1983). As recent taxonomic description (e.g. Lopez 2011 for Laonice vieitezi) shown, the existence of new species could have been easily overlooked in the past. The most important characters which set Laonice sp. 1 apart from Laonice weddellia are: chaetae arranged in two rows only in both rami (it is 4-5 in L. weddellia), and the later start of neuropodial hooks in segments 27-31 (it is 16-25 in L. weddellia), see comparative Tables 1. and 2. for details. Many small specimens, which agreed with Laonice sp. 1 were also recorded and are considered to be juveniles.
