Pseudopotamilla platensis ( Hartman, 1953 ),

Tovar-Hernández, María Ana, León-González, Jesús Ángel De & Bybee, David R., 2017, Sabellid worms from the Patagonian Shelf and Humboldt Current System (Annelida, Sabellidae): Phyllis Knight-Jones’ and José María Orensanz’s collections, Zootaxa 4283 (1), pp. 1-64: 48-50

publication ID 10.5281/zenodo.828032

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Pseudopotamilla platensis ( Hartman, 1953 )

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Pseudopotamilla platensis ( Hartman, 1953)  , new combination

( Figs 25–27View FIGURE 25View FIGURE 26View FIGURE 27, 33View FIGURE 33 C)

Potamilla platensis Hartman, 1953: 53  –54, fig. 19a –f.

Potamilla reniformis  .— Rullier & Amoreux 1979: 191.

Potamilla (Pseudopotamilla) reniformis  .— Augener 1931: 311.

Material examined. ARGENTINA, UANL 8104View Materials: Mar del Plata, Playa Grande, 38°01’30”S, 57°31’41”W, rocky intertidal, February 1965, coll. J.M. Orensanz, 1 specimenGoogleMaps  ; UANL 8105: Campaña R/V Almirante Saldanha, Sta. 2287, shelf off Mar del Plata, 38°05’S, 56°43.5’W, 67 m depth, 16 November 1969, 1 specimen; UANL 8107: Campaña SAO II, Golfo de San Matías, St. 125, 41°42’S, 64°52’W, 70 m depth, 3 May 1971, 1 specimen. URUGUAY, UANL 8108View Materials: R/ V Walther Herwig 15, St. 234, 35°14’S, 52°28’W, 200 m depth, 12 June 1966, 2 specimensGoogleMaps  ; UANL 8109: Campaña Akademik Knipovich, St. 1054, 35°56.5’S, 54°15.7’W, 58–65 m depth, 1967, coll. V.N. Semenova & V. Scarabino, 1 specimen; UANL 8110: St. 1059, 35°25.9’S, 53°27.9’W, 80– 72 m depth, 1967, coll. V.N. Semenova & V. Scarabino, 1 specimen.

Redescription. Trunk length 12–16 mm, width 2 mm. Branchial crown length 10 mm, with 14 pairs of radioles. Eight –12 thoracic and 48–62 abdominal segments. Radiolar flanges and palmate membrane absent. Long pinnules arranged in two alternating rows, decreasing in length distally; radiole tips short, as long as space of two pinnules ( Fig. 26View FIGURE 26 A). Compound eyes located proximally in dorsal radioles, except for dorsal-most pair; unequal in size within same radiole: radiole 2 (2–3 eyes), radiole 3 (2–3 eyes) ( Fig. 25View FIGURE 25 H, I). Branchial lobes short, with dorsal and ventral flanges: dorsal pair triangular ( Fig. 25View FIGURE 25 A, C, E), ventral pair rounded ( Fig. 25View FIGURE 25 D). Collar with dorsal margins fused to faecal groove; mid-dorsal collar margins long, triangular extending to base of radioles and covering one-half of branchial lobe dorsal flanges ( Fig. 25View FIGURE 25 A –C); dorso-lateral v-shaped incisions. Anterior peristomial ring partially exposed dorsally ( Fig. 25View FIGURE 25 B). Ventral lappets even, divided mid-ventrally by a depth incision (1/2 of the collar length). Dorsal lips triangular, erect, with radiolar appendages ( Fig. 26View FIGURE 26 B); ventral lips short, broadly triangular. Ventral sacs present. Ventral shield of chaetiger 1 entire, rectangular with anterior margin rounded ( Fig. 25View FIGURE 25 D). Chaetiger 1 notochaetae in two rows, broadly-hooded. Other thoracic shields rectangular but divided transversely ( Fig. 24View FIGURE 24 D, F). Second thoracic segment with pair of large, whitish glandular areas dorsolaterally ( Fig. 25View FIGURE 25 A, C, G). Thoracic neuropodial tori separated from ventral shields by broad gap ( Fig. 25View FIGURE 25 D). Superior notochaetae elongate narrowly-hooded; inferior thoracic chaetae paleate, arranged in two rows, with long and pointed mucro ( Fig. 27View FIGURE 27 A). Thoracic neuropodia with avicular uncini with several rows of small and similarlysized teeth above main fang; breast well developed ( Fig. 27View FIGURE 27 B), handles long, three times the length of main fang. Companion chaetae with asymmetrical membranes and long handles, slightly longer than uncini handles ( Fig. 27View FIGURE 27 B, C). Abdominal neurochaetae elongate broadly-hooded ( Fig. 27View FIGURE 27 D). Notopodia with uncini with several rows of teeth above main fang along two thirds of its length, breast well developed, handles short ( Fig. 27View FIGURE 27 E). Posterior abdomen narrow ( Fig. 26View FIGURE 26 D, E). Pygidium bilobed, eyes absent ( Fig. 26View FIGURE 26 D, E). Internal layer of tube translucent, chitinous; external surface covered by sand grains.

Type locality. North Argentina (37°15’S, 56°8’W), 100 m depth.GoogleMaps 

Remarks. In this study, Potamilla platensis  is shown to belong to Pseudopotamilla  , as it has unpaired compound eyes in dorsal radioles and flanges on bases of branchial lobes.

Pseudopotamilla reniformis ( Bruguière, 1789)  was reported by Augener (1931) as Potamilla (Pseudopotamilla) reniformis  , from near Golfo de San Matías (42°17’S, 62°20’W), and Rullier & Amoureux (1979) reported Potamilla reniformis  collected from 18–132 m depth at platforms off Brazil, Uruguay and ArgentinaGoogleMaps  . In this study, we consider records by Augener (1931) as belonging to P. platensis  because tubes, eye distribution and collar described by that author agree with those present in P. platensis  . According to João Nogueira, pers. com. (Universidade de São Paulo), records by Rullier & Amoureux (1979) from Brazil cannot be assigned to P. platensis  . 

For comparative purposes, we used images of Pseudopotamilla reniformis  from the White Sea, kindly shared by Glafira Kolbasova (Moscow State University) from adult forms, not exhibiting regeneration. The most distinctive features between P. platensis  and P. reniformis  is the presence of two large, dorsal glandular areas on chaetiger 2 (absent in P. reniformis  ); presence of 2–3 eyes only on radioles 2 and 3 (1–2 eyes on radioles 2 to +8 radioles in P. reniformis  ); mid-dorsal collar margins triangular and long (rounded and short in P. reniformis  ); and ventral lappets of collar even, divided by a depth incision (rounded, divided by a short incision in P. reniformis  ) ( Table 4).

Since its original description, there are no new records of Pseudopotamilla platensis  , although Obenat et al. (2001) recorded? Potamilla  sp. cf. P. platensis  in an ecological survey about 11–12 m depth, in aggregations of Phyllochaetopterus socialis Claparède, 1869  , near the Rio de la Plata mouth (35°23′– 35°31′S; 55°36′W - 55°48′W).

Differences between P. polyopthalma  and P. platensis  are the following: mid-dorsal collar margins are short, distally rounded in P. polyopthalma  (long, triangular in P. platensis  ); dorso-lateral glandular shields in chaetiger 2 absent in P. polyopthalma  (two glandular rectangular areas dorsally in P. platensis  ); 1–3 eyes present in dorsal and lateral radioles (radioles 2–6) in P. polyopthalma  (2–3 eyes in dorsal radioles 2–3 in P. platensis  ) ( Table 4).


Universidad Autonoma de Nuevo Leon














Pseudopotamilla platensis ( Hartman, 1953 )

Tovar-Hernández, María Ana, León-González, Jesús Ángel De & Bybee, David R. 2017

Potamilla reniformis

Rullier 1979: 191

Potamilla platensis

Hartman 1953: 53

Potamilla (Pseudopotamilla) reniformis

Augener 1931: 311