Parasabella Bush, 1905

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 : 27-28

Genus Parasabella Bush, 1905

Remarks. Perkins (1984) revised seven American species of Parasabella based on morphology and comparison of type material. Capa & Murray (2015) studied species of Parasabella from Australia based on the comparison of morphological data, nuclear and mitochondrial DNA sequence data. They found the presence of seven distinct genetic Parasabella lineages in Australia, four of which are assigned to previously described species, and two are considered as a complex of species. Capa & Murray (2015) emphasized that some of the more reliable features for distinguishing species are a combination of the degree of separation of ventral shields from thoracic neuropodial tori, the number of vacuolated axial cells supporting radioles near the base, absence/presence and arrangement of radiolar eyes, shapes of inferior thoracic notochaetae, lengths of handles of thoracic and abdominal uncini, and number and size of teeth over the main fang in uncini.

However, we assume that the degree of separation of ventral shields of thoracic tori can only be useful to separate species when working with adult forms without any evidence of regeneration. As noted in P. columbi ( Kinberg, 1867) (see below), as well as in Bispira brunnea ( Treadwell, 1917) (Dávila-Jiménez et al. 2017) , the lengths of tori and their indentation (or not) in ventral shields may be products of regeneration.

Currently, Parasabella includes 27 species after Tovar-Hernández & Harris (2010) and Capa & Murray (2015). Four species have been described from Argentina, Chile and Peru: P. columbi ( Kinberg, 1867) from La Plata ( Argentina), P. fernandezensis ( Augener, 1922) from Juan Fernandez Island, Chile, P. incerta ( Kinberg, 1867) and P. leucaspis ( Kinberg, 1867) , both from San Lorenzo ( Peru) ( Table 2).

Parasabella columbi has not been reported since its original description in 1867. Knight-Jones & Perkins (1998, p. 404) examined the type of Sabella fernandezensis Augener, 1922 , and concluded that it belongs to Demonax . Later, Tovar-Hernández & Harris (2010) formally transferred it to Parasabella . Johansson (1925, 1927) synonymized P. leucaspis with P. incerta Kinberg, 1867 , from Valparaiso, Chile, and other two species from Honolulu, Hawaii, P. cooki Kinberg, 1867 and P. krusensterni Kinberg, 1867 . Perkins (1984) followed the synonymies proposed by Johansson (1925), emphasizing differences among the types examined, with slight variations of shape of lower thoracic notochaetae between anterior and posterior rows, number of radioles, length of branchial crown compared with body length, width of thoracic ventral shields compared with body width and coloration of branchial crown. However, other features such as presence and extension of radiolar flanges were not detailed, as well as shape of dorsal margins of collar and abdominal chaetae. Detailed study of the variation in these features is needed to determine if Johansson (1925, 1927) and Perkins (1984) were correct in concluding that the types of P. leucaspis and P. incerta represent a single species.

In this study, we report the presence of P. columbi in Argentina and describe a new species from the Golfo de San José, also in Argentina .