Phylo Kinberg, 1866
Phylo felix heterosetosa Hartmann-Schröder, 1965
Voucher specimen. Loligo: Station L2FA, Vinson West: Station 3BMFA, Inflex: Station 3MFA.
Diagnosis. A large, robust species; vouchers incomplete, 2 large and 1 smaller specimens, 6-15mm long and 2-2.8mm wide for 35, 39 and 24 segments; thorax anteriorly wide, dorsoventrally flattened, narrowing posteriorly; abdomen cylindrical. Colour in alcohol dark yellow with brown inter-segmental patches mid-dorsally starting in between chaetigers 7-8 to 25-26; body segments narrow, crowded in abdomen. Prostomium short, conical, sharp. Branchiae from chaetiger 5 in smaller specimens or 6 in larger ones , continuing to the end of the fragments; strap-like, triangular, progressively increasing in size.
Thorax divided into anterior (chaetigers 1-11 in larger specimens and 1-10 in smaller ones) and posterior regions (chaetigers 12-16 and 11-15 respectively), categorised by spines in neuropodia, with ventral papillae. Notopodia of anterior thoracic region with elongated, slightly basally swollen bulbous postchaetal lobes and dense crenulated capillaries (long and short). Neuropodia of anterior thoracic region low lobes with a single row of large (up to 8), triangular podial papillae, with a single row of crenulated capillaries and 6 rows of modified spines; spines thick, short, distally bent, with transverse ridges, yellow to brown in colour. Notopodia of posterior thoracic region similar to preceding chaetigers; neuropodia of posterior thoracic region with 5 robust, dark yellow to light brown, protruding spines with enlarged, blunt, distal tip (not forming pronounced spear-head shape as in P. felix), in addition also modified spines of preceding segments (located ventrally to the large spines) and single row of crenulated capillaries. Ventrum of posterior thoracic region with ventral papillae (in addition to similar podial papillae in neuropodia), increasing in number from 1 (in ch. 12) to 6 to ~10.
Abdomen from chaetiger 16 or 17; with ventral papillae on chaetigers 17-21 (16-17 in small specimens), reducing in number from ~ 10 to 4 then 1 by chaetiger 21. Abdominal notopodia with lobe (similar to those in thorax), notopodia connected by low dorsal crests; long, slender, inter-ramal cirrus present. Neuropodia with barrel-shaped, distally notched lobes; small triangular ventral cirrus present. Notochaetae long, thin, serrated capillaries and furcate chaetae. Neurochaetae very few long capillaries (often broken off). Ventral papillae absent. Pygidium not observed.
Remarks. This species can be distinguished from Phylo felix in having 4 segments in posterior thoracic region (not 8-9), smaller number of neuropodial papillae in thorax with ~ 6 (not ~15), the presence of ventral papillae in up to 6 anteriormost abdominal chaetigers (as opposed to absent in abdomen). The smaller FI specimen is very similar to Phylo felix heterosetosa described by Hartmann-Schröder (1965) from Chile. In larger vouchers some variation occurs in that branchiae are present from chaetiger 6 (not 5). Also there are 11 segments in anterior thoracic region (not 10), the spines are clearly protruding well beyond the body wall in FI specimens and ventral papillae cover larger number of chaetigers.
Distribution. Chile, Falkland Islands in slope depths (~1000m).
