Aricidea (Acmira) Hartley, 1981
Aricidea (Acmira) simplex Day, 1963 (sensu Blake, 1996)
Voucher specimen. Sea Lion: Station 38MFB, Station 44MFA
Diagnosis. Vouchers are complete specimens 12-14 mm long, 0.8-0.9mm wide, for about 106-110 segments. Colour in alcohol opaque, white to light tan, sometimes dots of brown-reddish pigment on body segments. Body robust, thick, dorso-laterally flattened anteriorly, with numerous crowded segments, narrowing posteriorly.
Prostomium short wider than long, partially fused to peristomium. Antenna very short, clavate, arising from the posterior part of prostomium, reaching anterior margin of first chaetiger; eyes absent; pair of nuchal organs originating from posterior margin of prostomium, extending anteriorly as oblique slits nuchal slits, sometimes with dark pigment. Lateral lips of mouth formed by peristomium; posterior lip formed by chaetigers 1-2.
Branchiae from chaetiger 4, 16 pairs in voucher specimen, but can be variable; all branchiae except last few similar in size, very short (extending half way to dorsal midline), last few about half that length; each narrow, often narrowing to short, blunt terminal papilla.
Notopodial postchaetal lobes of chaetigers 1-3 shorter than following; those of branchial region longer, digitate somewhat inflated at the base, each about one-half as long as branchiae; lobes in postbanchiale segments becoming slender and long.
Capillary setae present in all parapodia becoming much longer in postbranchial segments; modified neurosetae from chaetigers 27 and 28 in two voucher specimens (this varies with size), each thick (stem somewhat bulging in the middle), can appear striated with yellow hues, distally curved, lacking arista, at first only one spine present, then increasing in number with up to 8 in posterior segments; accompanied by very fine capillaries. Pygidium collar-like segment with 1 short terminal cirrus and 2 long thin lateral ones.
Remarks. Aricidea simplex is very distinctive, and easily recognized by its thick, robust body, short head with the rounded prostomium, short antenna, and robust curved neuropodial spines. In specimens stained with Rose Bengal there are often distinct red stripes in the ventral anterior chaetigers. Preserved specimens are also often dorsally arched.
There appears to be some discrepancy when it comes to length of branchiae between South African and Pacific specimens. Day (1963, 1967) described anterior branchiae as overlapping at midline, however Blake (1996) noted that all branchiae are short (reaching half way to midline). Further there appear to be some differences in structure of spines, with Pacific specimens having shorter, stubbier and more strongly curved spines than those pictured by Day (1967). Specimens collected from FI agree well with Blake (1996) description in possessing short branchiae and robust, well curved spines. It is possible that they are actually different species but this requires examination of material from a range of localities which is beyond the scope of the present study.
Distribution. Apparently widespread but see Remarks above, found in outer shelf to lower continental slope depths 100¬3000+ m: South Africa; Uruguayan shelf; Patagonian shelf; Scotia Sea; Southern Ocean; New Zealand slope; Bering Sea; Japan; Caroline Islands; California, Falkland Islands.
