Polydora rickettsi Woodwick, 1961

Radashevsky, Vasily I., Lana, Paulo C. & Nalesso, Rosebel C., 2006, Morphology and biology of Polydora species (Polychaeta: Spionidae) boring into oyster shells in South America, with the description of a new species, Zootaxa 1353, pp. 1-37 : 22-24

Polydora rickettsi Woodwick, 1961

Polydora rickettsi Woodwick (1961, pp. 78–81, Figs 1–7 ). — Blake (1983, p. 257). — Radashevsky & Cárdenas (2004, pp. 244–252, Figs 2–6 ).

? Polydora sp. II: Carrasco (1976, pp. 34–37, Figs 12 , 13 L–O, 21C).

Polydora sp.: Basílio, Cañete & Rozbaczylo (1995, pp. 72–74, Fig. 1 A–H).

Polydora cf. rickettsi: Sato-Okoshi & Takatsuka (2001, pp. 489–490, Fig. 2 A–D).

Adult morphology (based on material from Brazil)

Specimens in poor condition. Up to 15 mm long and 0.6 mm wide at chaetiger 7 for 130 chaetigers. Black pigment diffused on palps along longitudinal ciliated grove, on sides of prostomium and on 1–4 anterior chaetigers; present only on prostomium or absent in some specimens. Largest individual with 130 chaetigers and with black bands on palps. Prostomium blunt to rounded anteriorly. Caruncle extending to middle of chaetiger 3. Occipital antenna absent. One to four eyes present or eyes absent.

Chaetiger 1 with short capillaries in neuropodia and postchaetal lamellae in both rami; notochaetae absent. Posterior notopodia with only capillary chaetae.

Chaetiger 5 greatly modified, with 2–3 dorsal superior capillaries, 4–6 major spines alternating with bilimbate-tipped companion chaetae, and ventral tuft of 4–6 capillaries; postchaetal lamellae absent. Dorsal superior and ventral capillaries shorter and fewer than those on chaetigers 4 and 6. Major spines falcate, with lateral tooth and narrow longitudinal flange located laterally on main fang above accessory tooth.

Branchiae from chaetiger 7 to almost end of body, full-sized from chaetiger 10–11, greatly diminishing on posterior chaetigers.

Hooks in neuropodia from chaetiger 7, bidentate, with constriction on shaft, up to 9 in a series.

Pygidium small, cup-shaped to disc-like with dorsal incision.

Gizzard-like structure in digestive tract not distinguished.

Remarks

Polydora rickettsi was originally described by Woodwick (1961) as associated with calcareous tubes of the serpulid polychaete Spirobranchus incrassatus Mörch from Lower California, Mexico. Sato-Okoshi & Takatsuka (2001) reported P. cf. rickettsi boring into shells of the oysters Crassostrea gigas and Ostrea chilensis (Philippi, 1845) in southern Chile. The worms resided in U-shaped burrows within the shells. More than 50 worms were found in one oyster shell, and 1–2 worms per cm2 were found on the shell surface ( Sato-Okoshi & Takatsuka 2001). Radashevsky & Cárdenas (2004) also described adult and larval morphology of the species from Chile and indicated that identification of the Chilean worms should be verified by further studies on specimens from Mexico.

In Brazil, worms were found in a shell of the scallop Nodipecten nodosus (Linnaeus, 1758) . The scallop was collected off the coast of the state of São Paulo and maintained for a long time in an aquarium of the University of São Paulo (USP). The fixed scallop shell with worms was received for examination from João M. de M. Nogueira in 2001. Specimens from Brazil appear similar to P. rickettsi from Chile. Both have an entire prostomium, characteristic falcate spines on chaetiger 5, and a small disc-like pygidium. The only difference is that the largest specimen (with 130 chaetigers) from Brazil has black bands on the palps and black pigment on the sides of the prostomium. Worms from Mexico and Chile (largest with 125 chaetigers) have no such pigmentation on palps. The presence of black bars or bands on palps is a diagnostic feature appearing stable in some species (e.g., Polydora brevipalpa Zachs, 1933 ) and variable in others (e.g., P. ecuadoriana , P. h a s w e l l i, P. neocaeca ). Further studies are needed to verify the identification of worms boring in N. nodosus in Brazil.

Distribution

Pacific Mexico; Chile;? Brazil: São Paulo.

Figures

FIGURE 1. Map showing reports of Polydora ecuadoriana (1 — Blake, 1983) and Polydora cf. haswelli in South America. New records of both species from Brazil are depicted by filled circles: ES — Espírito Santo, RJ — Rio de Janeiro, SP — São Paulo, PR — Paraná, SC — Santa Catarina.

FIGURE 2. Polydora ecuadoriana adult morphology, Paraná (USNM 1022185). A, anterior end of a 40 - chaetiger juvenile, dorsal view, showing narrow black band along ciliated groove on right palp; left palp omitted. B, bidentate hooded hook from neuropodium of chaetiger 20. C, bidentate hooded hook from neuropodium of chaetiger 7. D, heavy falcate spines and bilimbate-tipped companion chaetae from notopodium of chaetiger 5; right side chaetae in ventral view; older, worn chaetae on right.

FIGURE 3. Polydora ecuadoriana adult morphology and distribution of fertile (gametogenic) chaetigers, São Paulo and Paraná. A, relationships between number of eyes and total number of chaetigers in worm, and distribution of number of eyes in population. B, relationships between pigmentation of palps and total number of chaetigers in worm; abs — absence of pigmentation on palp; line — black line along longitudinal ciliated groove on palp; 2 – 7 — number of black bars on palp. C, relationships between length of caruncle and total number of chaetigers in worm. D, relationships between position of the first and last fertile chaetigers and total number of chaetigers in males. E, same in females.

FIGURE 4. Polydora ecuadoriana adult morphology, Paraná (USNM 1022185). A, anterior end, dorsal view, showing palp scars (pa), lateral organs (lo) on chaetiger 1, ciliary bands of nuchal organs (no), nototrochs (nt), and flattened branchiae (br) from chaetiger 7. B – E, posterior end in various views, showing large, scoop-shaped pygidium with wide middorsal gap, dorsal anus (an), and postanal ciliary band (cb). Scales: A – E, 100 µm.

FIGURE 5. Polydora ecuadoriana adult morphology, Paraná (USNM 1022185). A, anterior end, left lateral view, showing narrow, downwards-curved prostomium (pr), low caruncle (ca), and peristomium (pe). B, same, ventral view, showing narrow incision on anterior edge of prostomium. C, chaetigers 2 – 6, left lateral view, showing lateral ciliated organs (lo) on chaetigers 2, 3 and 6; enlarged chaetiger 5 with tuft of dorsal superior capillaries (ds), two kinds of modified notochaetae (mn) arranged in horizontal double row, and tuft of ventral capillaries (vc). D, chaetigers 6 – 8, left lateral view, showing ventral capillaries on chaetiger 6, vertical rows of hooded hooks (hh) and external parts of secretory cells of glandular pouches (gp) on chaetigers 7 and 8. E, F, posterior ends in left lateral view, showing various pygidia. Scales: A, B, F, 100 µm. C, E, 50 µm. D, 30 µm.

FIGURE 6. Polydora ecuadoriana shell-boring life style Espírito Santo (MZSP 168). A, pair of feeding palps protruding out of short silty tube that extends burrow in shell, showing characteristic black bars regularly arranged along length of each palp. B, external opening of burrow in shell, with silty tube extensions removed, showing joined apertures and pair of short palps. C, shells of mangrove oyster Crassostrea rhizophorae infested by Polydora ecuadoriana, showing U-shaped burrows (bu) and small mud blisters (mb) with worms on inner side of shells. Scales: A, B, 1 mm. C, 1 cm.

FIGURE 7. Polydora ecuadoriana life cycle diagram. A, sinuous spermatophore released by male and caught by female. B, female brooding early larvae in egg capsules joined to each other in string, with each attached by two stalks to inner wall of burrow in shell. C, fragment of egg capsule string. D, 3 - chaetiger larva hatched from egg capsule and entered into the plankton. E, 16 - chaetiger pelagic larva ready for settlement and metamorphosis. F, juvenile in silty tube at beginning of boring into shell, with palps lacking pigmentation.

FIGURE 12. Polydora carinhosa sp. nov. larval morphology, Paraná. A, anterior fragment of early 14 - chaetiger larva from egg capsule, dorsal view, showing short caruncle with one pair of large glandular cells, and rounded nuchal ciliary patches on the posterior dorso-lateral sides of the prostomium. B – C, late 14 - chaetiger larva from egg capsule, showing pigmentation pattern. B, dorsal view, showing arrangement of melanophores. C, ventral view, showing distribution of yellow pigment.

FIGURE 13. Polydora carinhosa sp. nov. life cycle diagram. A, female brooding larvae in egg capsules joined to each other in string, with each attached by two stalks to inner wall of burrow in shell. B, fragment of egg capsule string. C, 14 - chaetiger larva hatched from egg capsule and ready for settlement and metamorphosis. D, juvenile in silty tube at beginning of boring into shell.