Perkinsiana assimilis ( McIntosh, 1885 )

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: 39-43

publication ID 10.5281/zenodo.828032

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Perkinsiana assimilis ( McIntosh, 1885 )


Perkinsiana assimilis ( McIntosh, 1885)  , redescription

( Figs 19–21View FIGURE 19View FIGURE 20View FIGURE 21, 33View FIGURE 33 B)

Sabella assimilis McIntosh, 1885: 488  –489, pl. 29A, figs 23–25.

Perkinsiana assimilis  .— Knight-Jones 1983: 280 –281, fig. 16A –K.

Material examined. ARGENTINA, R/ V Walther Herwig, UANL 8077View Materials: Sta. 231, 35°14’S, 52°21’W, 200 m depth, 12 June 1966, 20 specimensGoogleMaps  ; UANL 8078: Sta. 383, 40°22’S, 59°02’W, 90 m depth, 19 July 1966, 1 specimen; UANL 8079: Sta. 391, 38°53’S, 55°22’W, 400 m depth, 21 July 1966, 10 specimens; UANL 8080: Sta. 392, 38°49’S, 55°14’W, 500 m depth, on gastropod shells, 21 July 1966, 8 specimens; UANL 8081: Sta. 389, 38°56’S, 55°31’W, 200 m depth, 21 July 1966, 4 specimens; UANL 8082: Sta. 399, 37°51’S, 55°10’W, 250 m depth, 22 July 1966, 26 specimens; UANL 8083: Sta. 400, 37°23’S, 54°48’W, 200 m depth, 23 July 1966, 6 specimens; UANL 8084: Sta. 415, 35°51’S, 52°53’W, 270 m depth, 25 July 1966, 2 specimens. Campaña Almirante Saldanha , UANL 8085View Materials: 2286, 38°05’S, 55°48’W, 95 m depth, 16 November 1969, 1 specimenGoogleMaps  . Campaña SAO II, UANL 8086View Materials: Golfo de San Matías, St. 111, 41°08’S, 64°53’W, 111 m depth, 30 April 1971, 2 specimensGoogleMaps  .

Redescription. Trunk length 34–60 mm; width 2–4 mm. Branchial crown length 9–16 mm, with 16–26 pairs of radioles. Four to five pairs of ventrally involute radioles. Thorax with 4–8 segments. Abdomen with 52–120 segments. Palmate membrane and radiolar flanges absent ( Fig. 20View FIGURE 20 A, D, E). Longest pinnules at mid-radioles. Radioles with long tips, as long as equivalent space of 15 pinnules ( Fig. 20View FIGURE 20 C). Dorsal lips triangular ( Fig. 20View FIGURE 20 B, F, G), erect, with distinct radiolar appendages and very narrow lateral lamella, 2–3 dorsal pinnular appendages united by thin membrane. Ventral lips broadly rounded ( Fig. 20View FIGURE 20 B), with 1–2 ventral pinnular appendages. Parallel lamellae present; ventral sacs visible above collar ventral lappets ( Fig. 19View FIGURE 19 E). Dorsal collar margins not fused to faecal groove ( Fig. 19View FIGURE 19 A, D, F). Anterior peristomial ring even all around, dorsally exposed ( Fig. 19View FIGURE 19 A, D, F). Ventral lappets of collar distally rounded, not overlapping ( Fig. 19View FIGURE 19 B, E). Lateral collar margins oblique, higher ventrally, covering junction between anterior peristomial ring and branchial lobes ( Fig. 19View FIGURE 19 C). Ventral shield of chaetiger 1 divided transversely: anterior part thin, subdivided mid-ventrally in two triangular areas; posterior part wide, rectangular with anterior margin convex ( Fig. 19View FIGURE 19 B, E). Chaetiger 1 with narrowly hooded notochaetae.

Thoracic ventral shields trapezoidal ( Fig. 19View FIGURE 19 B). Thoracic neuropodial tori of equal length, contacting ventral shields ( Fig. 19View FIGURE 19 B, C). Superior thoracic notochaetae narrowly hooded ( Fig. 21View FIGURE 21 A), hood one-half width of shaft. Inferior thoracic notochaetae paleate ( Fig. 21View FIGURE 21 C), symmetrical, hood as wide as shaft, short mucro. Thoracic uncini with 7–8 rows of teeth of equal size above main fang, occupying one-half length of main fang, hood absent, breast well developed, handles 2.5 times longer than main fang ( Fig. 21View FIGURE 21 B). Companion chaetae with teardrop-shaped membranes, asymmetrical ( Fig. 21View FIGURE 21 E). Abdominal neurochaetae elongate, narrowly hooded; hood one-half width of shaft, slightly curved at base of hooded area, Type C ( Fig. 21View FIGURE 21 D). Abdominal uncini with dentition similar as in thorax (7–8 teeth covering half the main fang), but with handles as long as 1.5 length of main fang ( Fig. 21View FIGURE 21 F). Pygidium triangular, eyes absent ( Fig. 19View FIGURE 19 G); anus ventral. Tubes translucent green, rigid, distally covered with gravel and proximally with sponges ( Fig. 19View FIGURE 19 D, E).

Type locality. Near Buenos Aires ( Argentina) at 1100 m depth. 

Remarks. Perkinsiana assimilis  is herein reported from 90–500 m depth, on the Uruguayan and Argentine shelf. Perkinsiana assimilis  is distinctive due to the absence of a palmate membrane (present in P. magalhaensis  ) and radiolar flanges (present in P. antarctica  and P. magalhaensis  ), as well as the presence of long radiolar tips (very short in P. antarctica  ) ( Table 3).

Among the species of Perkinsiana  distributed in South America, only P. corcovandensis  and P. pusilla  have Type A abdominal chaetae, whereas in P. antarctica  , P. assimilis  , P. magalhaensis  and P. minuta  they are Type C ( Table 3). In P. antarctica  the ventral shield of the chaetiger 1 is entire and rectangular. In P. magalhaensis  it is divided transversely in two parts, the anterior one slightly narrower than posterior. Sometimes the shield is also divided mid-ventrally, forming four square areas.

Two specimens (UANL 8078) were found with regenerating branchial crowns, and one regenerating posterior abdominal segments. Regeneration was also reported among type material by Knight-Jones (1983).


Universidad Autonoma de Nuevo Leon


Sammlung Oberli














Perkinsiana assimilis ( McIntosh, 1885 )

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

Perkinsiana assimilis

Knight-Jones 1983: 280

Sabella assimilis

McIntosh 1885: 488