Parasabella columbi ( Kinberg, 1867 )

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: 28-31

publication ID

10.5281/zenodo.828032

publication LSID

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persistent identifier

http://treatment.plazi.org/id/EE3E87C6-FFB0-A352-FF7F-DC09FEDB5993

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scientific name

Parasabella columbi ( Kinberg, 1867 )
status

 

Parasabella columbi ( Kinberg, 1867)  , redescription

( Figs 13View FIGURE 13, 14View FIGURE 14, 32View FIGURE 32 C)

Sabella columbi Kinberg, 1867: 353  ; 1910: 72, pl. 28, fig. 3.— Johansson 1925: 10, fig. 3 (1–4).— Johansson 1927: 128.— Hartman 1949: 15.— Hartman 1969: 559.

Demonax columbi  .— Knight-Jones & Perkins 1998: 404.

Parasabella columbi  .— Tovar-Hernández & Harris 2010: 3.

Material examined. ARGENTINA, UANLAbout UANL 8063View Materials: Campaña SAOAbout SAO I, Golfo de San Matías , St. 46, 41°27’S, 64°57’W, 36 m depth, gravel, February 1971, coll. J.M. Orensanz, 2 specimensGoogleMaps  . UANLAbout UANL 8064View Materials: Golfo de San José, Isla de los Pájaros , 42°25’S, 64°31’W, sand flat, low intertidal, in patches of Phyllochaetopterus  , coll. J.M. Orensanz, 18 January 1975, 1 specimenGoogleMaps  . UANLAbout UANL 8065View Materials: Campaña Sanjo II, Golfo de San José, off Las Covachas, E of Punta Tehuelche , 42°24’S, 64°19’W, scallop ground, May 1976, coll. J.M. Orensanz, 1 specimen regenerating posterior abdomenGoogleMaps  . UANLAbout UANL 8066–8067View Materials: Puerto Deseado, Dos Hermanas , 10 March 1981, coll. P. Knight-Jones & W.Knight-Jones, on bed rock at foot of waterfall, 20 specimens, and on holdfasts and rocks, 10 specimens, respectively  . UANLAbout UANL 8068View Materials: Golfo de San José, Banco de Enfrente, El Riacho , intertidal mussel bed on sand, December 2005, coll. J.M. Orensanz, 44 specimens, 12 specimens regenerating. 

Redescription. Trunk length 17 mm; width 1.5 – 3 mm. Branchial crown length 5 – 6 mm, with 7 – 11 pairs of radioles. Thorax with 5 – 8 segments (17 specimens with 6 segments, 2 with 5 segments, 1 with 8 segments). Abdomen with 101 – 103 segments for complete specimens. Semicircular branchial lobes, fused dorsally ( Fig. 13View FIGURE 13 A), separate ventrally ( Fig. 13View FIGURE 13 B). Radioles with brown pinnules along entire radiolar length ( Fig. 13View FIGURE 13 A, B). Palmate membrane and radiolar eyes absent. Radioles with narrow flanges along entire lengths ( Fig. 13View FIGURE 13 D), wider towards radiolar tips ( Fig. 13View FIGURE 13 C). Longest pinnules at mid-radiole lenght. Radioles with short, flattened, digitiform tips, as long as equivalent space of 8 – 9 pinnules ( Fig. 13View FIGURE 13 C). Dorsal lips triangular ( Fig. 13View FIGURE 13 F), as long as 1/4 branchial crown length, erect, with distinct longitudinal brown radiolar appendage forming two lateral lamellae and one dorsal pinnular appendage. Ventral lips broadly rounded ( Fig. 13View FIGURE 13 E), brown, with two ventral pinnular appendages. Parallel lamellae present. Mid-dorsal collar margins not fused to faecal groove, exposing anterior peristomial ring ( Fig. 14View FIGURE 14 A, B). Ventral collar lappets triangular with rounded distal margins ( Fig. 14View FIGURE 14 C, D), not overlapping when contracted (slightly overlapped when retracted). Lateral collar margins even, covering basal union of radioles. Ventral shield of chaetiger 1 swollen, quadrangular with rounded antero-lateral corners and slight antero-medial indentation, two times longer than second thoracic shield ( Fig. 14View FIGURE 14 B, C). Collar with double row of elongate narrowly hooded chaetae. Body uniformly slender. Faecal groove wide and depth in thorax ( Fig. 14View FIGURE 14 A, B).

Thoracic ventral shields rectangular ( Fig. 14View FIGURE 14 C, D). First thoracic torus slightly shorter than others, not contacting ventral shield. Second thoracic neuropodial torus contacting or not contacting ventral shield. Third to sixth thoracic tori always contacting shields ( Fig. 14View FIGURE 14 C, D). Superior thoracic notochaetae narrowly hooded, two times longer than inferior group, hood 1/8 times wider than shaft. Inferior thoracic notochaetae narrowly hooded (Type B: slender hoods and a progressively tapering distal tip according to Capa & Murray, 2015) ( Fig. 13View FIGURE 13 G), shorter than superior notochaetae, hood 1/4 times wider than shaft. Thoracic uncini with 5 – 7 rows of equal size teeth above main fang, occupying one-half of main fang length, hood absent, breast well developed, handles as long as two times the distance from main fang to breast (medium size). Companion chaetae with denticulate bulbous head with one tooth longer, with elongate membranous tip ( Fig. 13View FIGURE 13 K). Abdominal neurochaetae with two rows of elongate narrowly hooded (all chaetae equal in size). Abdominal uncini with dentition similar to those in thorax but with handles short, as long as main fang. Pygidium bilobed ( Fig. 14View FIGURE 14 E, F). Pygidial eyes absent. Tubes amber colored, covered with sand grains.

Type locality. La Plata, Argentina.

Remarks. Parasabella columbi  was described as Sabella  by Kinberg (1867) from La Plata (Argentina) and illustrated posteriorly in Kinberg (1910: pl. 28, fig. 3). Johansson (1925) examined the holotype (NRM 1084), that is broken into four parts: branchial crown, thorax, anterior abdomen and posterior abdomen, considering it as a member of Sabella  . Due to bad preservation and rupture of the type, Johansson did not add other characters to Kinberg’s description (1867) and drawings (1910), except for some chaetae. Later, Knight-Jones & Perkins (1998: 404) grouped it with Demonax  based on the examination of the holotype but a description was not provided. The species was only known for the type locality. In this study, we report and redescribe P. columbi  from several localities in Golfo de San José (Argentina).

Parasabella columbi  has ventral shield of chaetiger 1 quadrangular, twice as long as the length of 2nd thoracic shield (in P. leucaspis  complex and P. yonowae  sp. nov., it is rectangular, 1.5 longer than the length of 2nd thoracic shield). In P. columbi  , P. leucaspis  complex and P. yonowae  , radiolar tips are digitiform versus lanceolate, leaf-like as in P. fernandezensis  . The ventral lappets of collar are triangular, long in P. columbi  (rounded, short in P. leucaspis  complex and P. yonowae  ) Parasabella columbi  does not have pygidial eyes whereas they are present in P. fernandezensis  and P. yonowae  ) ( Table 2).

Regarding the shape of broadly hooded inferior thoracic notochaetae, Capa & Murray (2015) show that a range of forms are present, from those with broader hoods and distal ends narrowing abruptly (referred to as type A), and those with more slenderer hoods and a progressively tapering distal tip (referred to as type B). Type A is found in P. leucaspis  ( fide Capa & Murray 2015  ), whereas type B is present in P. columbi  , P. fernandezensis  and P. yonowae  sp. nov. ( Table 2).

Lengths of handles of thoracic uncini in Parasabella  were also classified by Capa & Murray (2015) as short (less than the distance from the main fang to breast), medium (1–2 times distance from main fang to breast), and long (2.5 to 3.5 times distance main fang and breast). All species from South America ( P. leucaspis  P. columbi  , P. fernandezensis  and P. yonowae  sp. nov.) have handles of medium length.

Transverse fission and regeneration is a common phenomenon in P. columbi  ( Fig. 13View FIGURE 13 H, J). This process was found in 13, out of 45 specimens (28.8%). In these worms, branchial crowns exhibit some degree of regeneration: radioles may be short, thin ( Fig. 13View FIGURE 13 H, I), or rudimentary ( Fig. 13View FIGURE 13 J). The number of thoracic segments is variable in worms where branchial crowns are at an advanced regeneration stage, with 5–6 thoracic segments being the most common condition ( Fig. 13View FIGURE 13 I). In these regenerating worms, the first thoracic neuropodial torus does not contact the ventral shields ( Fig. 13View FIGURE 13 I), in comparison to non-regenerating worms, in which the first thoracic tori always contacts shields ( Fig. 14View FIGURE 14 D). In other regenerating worms, there are abdominal segments immediately posterior to the regenerated branchial crowns, indicated by 1) the presence of ventral abdominal shields divided longitudinally by the faecal groove; 2) chaetal arrangement and reorganizing chaetigers (some anterior segments lost chaetae and uncini; others have two pairs of parapodia in a single segment; or the most anterior segments have neuro and notochaetae (as regular abdominal chaetal arrangement) and the following posterior segments have noto- and neurochaeta (as regular thoracic chaetal arrangement), but with ventral abdominal shields. Thus, tori contacting (or lack of contact) with the ventral shields is not a diagnostic feature for species level identification, and must be used with carefully.

UANL

Universidad Autonoma de Nuevo Leon

SAO

Sammlung Oberli

Kingdom

Animalia

Phylum

Annelida

Class

Polychaeta

Order

Sabellida

Family

Sabellidae

Genus

Parasabella

Loc

Parasabella columbi ( Kinberg, 1867 )

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

2017
Loc

Parasabella columbi

Tovar-Hernandez 2010: 3

2010
Loc

Demonax columbi

Knight-Jones 1998: 404

1998
Loc

Sabella columbi

Hartman 1969: 559
Hartman 1949: 15
Johansson 1927: 128
Johansson 1925: 10Kinberg 1867: 353

1925