Aricidea (Allia) Strelzov, 1973
Aricidea (Allia) cf. antennata Annenkova, 1934
Voucher. INFLEXIBLE: Station 1MFA.
Diagnosis. Medium sized, robust species. Voucher specimen incomplete with 35 segments, 2.5mm long and 0.75mm wide. Body robust, dorsoventrally flattened with crowded segments in anterior part of the body, widest between chaetigers 4-9; colour in alcohol dark yellow.
Prostomium much wider than long, often arched dorsally with hunchback look, large middle lobe anteriorly flattened and separated from the side lobes by notches; nuchal slits prominent on two prostomial lateral lobes. Long thin antenna extends to chaetiger 5 in voucher specimen.
Branchiae from chaetiger 4, 8 pairs, not meeting at midline where the body is widest (chaetigers 4-9), reducing in size posteriorly (reaching midline as the body becomes more narrow), all very broad, oval, distally narrowing into short but acute tips.
Notopodial postchaetal lobes developed, smaller on segments 1-3 then getting longer in branchial region, branched (bi-lobed) lobes occur on segments 3- 8 (the second branch is extremely small in chaetiger 3, but clearly observed in shirla-stained specimens). Neuropodial lobes prominent, oval flaps, largest in branchial region.
Notochaetae always capillaries, long and dense in anterior part of the body; modified neurochaetae begin to transition from chaetiger 21 in voucher specimen, increasing in number and in thickness (up to 7 per fascicle on the last segment), only thickened gently curved chaetae with long thin arista observed in 35 chaetigers long fragment, accompanied by several long capillaries.
Pygidium not observed.
Remarks. Aricidea antennata and A. quadrilobata Webster and Benedict, 1887 were synonimized by Strelzov (1973), but represent distinct species according to Blake (1996) who based this conclusion on an examination of numerous specimens from both the Atlantic and Pacific sides of North America. According to Blake (1996) the Atlantic species should be called A. quadrilobata and has the broad prostomium and single notopodial postsetal lobes, while the Pacific form has the truncated prostomium and double notopodial lobes. Our specimens agree well with A. antennata in possessing double notopodial lobes in anterior segments 3-8, although Blake's specimens had these in segments 5 -14. Further, there appear to be some differences in branchial structure as Blake's Pacific specimens have posterior branchiae with long, filamentous tips, but tips in FI specimens are all short. Heavy spines reported by Blake were not observed, but it is possible that FI specimens are too shorter fragments in order to observe full variety of modified notochaetae. Until more material is available, we assign the FI specimens to Aricidea (Allia) cf. antennata Annenkova, 1934.
