Pilargis, de Saint-Joseph, 1899

Salazar-Vallejo, Sergio I. & Harris, Leslie H., 2006, Revision of Pilargis de Saint-Joseph, 1899 (Annelida, Polychaeta, Pilargidae), Journal of Natural History 40 (3 - 4), pp. 119-159 : 133

Pilargis sp. California, juvenile

( Figure 4E )

Material examined

Eastern Pacific Ocean: one specimen (LACMNH), collected during the Southern California Bureau of Land Management Study, accession number 85401, code BF1, no further data.

Description

Specimen complete, body folded, transparent, pale; slightly pigmented prostomium, pharynx and gut contents, 4.5 mm long, 2 mm wide, 22 setigers and eight asetigers. Integument rugose but without verrucae ( Figure 4E ).

Prostomium dorsally distinct from peristomium, not embraced by the peristomium, about twice as long as peristomium; palps rounded, massive, palpostyles elongated. Antennae cirriform rising from posterior margin of prostomium; few dorsal eyespots slightly ahead of antennae, arranged in two lateral and one median groups. Tentacular cirri cirriform, dorsal tentacular cirri about as long and wide as ventral tentacular cirri.

Parapodia elongated. First dorsal cirri as long as second dorsal cirri. Dorsal cirrophore elongated truncate cone, no glandular material visible either on the surface or below the integument. No pigment spots over ventral parapodial lobe. Dorsal cirrostyles digitate, elongated, no distinction observable from cirrophore. Ventral cirri cirriform, elongated, longer than setal lobe, about as long as dorsal cirri. Neurosetae include very long capillaries and smaller finely spinulose bidentates.

Pygidium rounded, two conical, ventrolateral anal cirri, as long as last three to four asetigers. Pharynx conical, wider anteriorly, as long as first three setigers. Gut diverticula penetrate about half parapodial lobe in setigers 1–9; from setiger 10, diverticula not yet formed; gut empty but in posterior region with fine particles and sediments.

Discussion

By the presence of elongated capillary setae and by the incomplete development of the gut diverticula and posterior end, this form is an early juvenile or a just settled postlarva. Whether it belongs to other species in the region like P. berkeleyae or P. maculata (see below) is difficult to say, because there is no glandular development. However, because of the long dorsal cirrophore, it may be conspecific with P. angeli n. sp., but the setae differ. There are no other records of juvenile or postlarval Pilargis , and the few records available are on Ancistrosyllis ( Bhaud 1974; Blake 1975); it is interesting that this juvenile has antennae placed towards the posterior end of the prostomium; they could migrate anteriorly as the peristomium grows more laterally and fuses with the prostomium. Tentacular cirri and parapodial cirri are little specialized too, they undertake differential growth since in adults, dorsal tentacular cirri is longer than ventral one, dorsal cirri of first setiger becomes larger than those present in setiger 2, and ventral cirri is smaller than dorsal cirri. More and better materials would help in solving its affinity or specific placement.

Figures

Figure 4. (A–D) Pilargis angeli n. sp. UANL-1474: (A) anterior end in dorsal view (verrucae are mostly restricted to parapodia); (B) right setiger 10 in anterior view; (C) median setiger in anterior view; (D) right setiger 60 in anterior view. (E) Pilargis sp. juvenile BLM 85401 BF1, complete organism in dorsal view, slightly distorted by cover slip. Scale bars: 225 mm (A); 120 mm (B–D); 500 mm (E).