Phylo Kinberg, 1866
Phylo cf. felix Kinberg, 1866
Voucher specimens. Sea Lion: Station 65MFC (adult), Station 51MFA (adult), Station 29MFA (juvenile), Station 37MFC (juvenile).
Diagnosis (Adult). A large, robust species; vouchers incomplete 29 - 45mm long and 2.7 - 3mm wide for 50 and 58 segments; thorax anteriorly wide, dorsoventrally flattened, narrowing posteriorly; abdomen cylindrical. Colour in alcohol dark yellow. Prostomium short, conical, sharp. Branchiae from chaetiger 5, continuing to the end of the fragments, strap-like, triangular, progressively increasing in size. Thorax divided into anterior (chaetigers 1-10) and posterior (chaetigers 11-18(19)) areas, with spear-shaped spines in neuropodia, with ventral papillae regions. Notopodia of anterior thoracic region with large bulbous (very wide and round basally extending into slender tip) postchaetal lobes and dense crenulated capillaries (long and sort). Neuropodia of anterior thoracic region low lobes with a single row of large (up to 15), triangular podial papillae, with single row of crenulated capillaries and 3 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 5-7 large, brown, protruding, spear-shaped spines (often broken off but dark broken stems can be observed). In addition to modified spines and crenulated capillaries; posterior thoracic region with ventral papillae (in addition to similar podial papillae in neuropodia), up to around 20, greatly reduced in number (around 5) in the last chaetiger of this region.
Abdomen from chaetiger 18-19; with bulbous notopodial lobe (similar to those in thorax); long, slender, lanceolate (slightly bulging in the middle) inter-ramal cirrus present; neuropodia with barrel-shaped distally notched lobes; with small triangular ventral cirrus. Notochaetae long, thin, serrated capillaries and furcate chaetae; neurochaetae very few long capillaries (often broken off). Ventral papillae absent. Pygidium not observed.
Diagnosis (Juvenile). Smaller than adults; vouchers incomplete 3 - 5.5mm long and 0.7 - 0.8mm wide for 25 and 30 segments; body shape as in adults; branchiae start from chaetiger 5 as in adults. Thorax (overall) shorter than in adults; anterior region with 1-10 chaetigers (as in adults), posterior region much shorter than in adults with 2-4 chaetigers, bearing protruding spear-shaped spines (often broken off); spear-shaped spines less robust than in adults, often colourless or with yellow to light brown hues, 2-3 per ramus, Ventral papillae present in posterior thoracic region (but in the smallest specimens these are not developed). Abdomen as in adults. All other chaetae as in adults.
Remarks. The juvenile specimens can be easily misidentified as Orbinia (if the ventral papillae are clearly present) or as Scoloplos (if the ventral papillae are very few or overlooked), because the spear-shaped spines (hallmark of genus Phylo) are so often broken off. While in adults the spear-shaped spines are also often broken off, their dark, robust stems can be clearly visible. This is often not the case for juveniles (although this is somewhat dependent on the size of the juveniles) and careful examination under compound microscope may be necessary.
There appears to be some variation in specimens identified as Phylo felix by previous authors subsequent to species original description by Kinberg (1866) (see Ehlers 1900, 1901, Monro 1930, Hartman 1966). Phylo felix heterosetosa has been described by Hartmann-Schröder (1965) from Chile as a result of this variation (e.g. spines not protruding from body wall), but it is possible that other as yet unrecognised species may be present. For example, Hartman (1966) reported spear-shaped spines protruding in chaetigers 11-19 (consistent with FI specimens) in Phylo felix, but ventral papillae were present in chaetigers 11(12) 20 (21), while in FI specimens (adults) the ventral papillae are found in chaetigers 14-18 (19). However it is not possible to establish this without re-examination of specimens from different locations and revision should be carried out.