Terebella Linnaeus, 1767

Santos, Andre Souza Dos, Nogueira, João Miguel De Matos, Fukuda, Marcelo Veronesi & Christoffersen, Martin Lindsey, 2010, New terebellids (Polychaeta: Terebellidae) from northeastern Brazil, Zootaxa 2389 (1), pp. 1-46 : 15

Genus Terebella Linnaeus, 1767

Type-species: Terebella lapidaria Linnaeus, 1767 , by monotypy.

Diagnosis. Terebellines with 3 pairs of branching branchiae, on segments 2–4, or on discontinuous segments. Lobes on anterior segments absent. Notopodia beginning from segment 4, extending for variable number of segments, frequently until posterior body; notochaetae distally serrated, with or without hispid wing at midlength, frequently both types present. Neuropodia starting from segment 5, sessile throughout; uncini shorthandled, arranged in double rows from segment 11 to posterior body.

Remarks. Terebella is a well known genus, reported worldwide. The genus presents variation in several characters which are not variable in the other genera of terebellines. The origin of the pairs of branchiae, for example, is variable in this genus, because although most species have branchiae inserted on segments 2–4, some species have pairs of branchiae inserted more posteriorly, on discontinuous segments ( Hutchings & Glasby 1988). However, the genera Polymniella Verrill, 1900 and Terebellobranchia Day, 1951 are characterized by having pairs of branchiae inserted on discontinuous segments, and are otherwise very similar to species of Terebella . Therefore, if it is accepted that the insertion of the pairs of branchiae is variable within Terebella , the genera Polymniella and Terebellobranchia should be considered as junior synonyms of this genus (see Nogueira 2008; Nogueira et al. in press).

The number of pairs of notopodia is another variable character within Terebella , since some species, such as T. leslieae sp. nov. (see below), have notopodia extending for a limited number of segments, with well marked “thoracic” and “abdominal” regions, while other species, including T. lapidaria and T. cf. verrilli ( Verrill, 1873) sensu Nogueira, 2008 , for example, have notopodia extending to posterior body and body regions are not clearly differentiated.

All species of Terebella have distally serrated notochaetae, but there is intrageneric variation on the subtypes of distally serrated notochaetae present. Most species, including T. lapidaria , have medially winged notochaetae with distally serrated blade on anterior notopodia, and not-winged notochaetae with distally serrated blade at an angle with the shaft on posterior chaetigers. Other species, however, such as T. pappus Hutchings & Murray, 1984 and T. tantabiddycreekensis Hartmann-Schröder, 1980 , have the same type of notochaetae throughout, not presenting a transition on the subtype of notochaetae from anterior to posterior notopodia. Most, if not all species of Terebella known previously to this study, however, have the same type of notochaetae on anterior and posterior tiers within the same notopodium, but T. leslieae sp. nov., has notochaetae from anterior tier different from those from posterior tier throughout and does not present transition on the subtypes of notochaetae present along the body (see below).

Finally, differently from what occurs in most other genera of terebellines, the arrangement of the double rows of uncini is also variable within Terebella . Most species have completely separated rows of uncini, with rows facing each other in a beak-to-beak arrangement, as is the case of T. lapidaria and T. cf. verrilli sensu Nogueira, 2008 , for example, but at least T. gorgonae Monro, 1933 has rows of uncini in a back-to-back arrangement ( Capa & Hutchings 2006), and a few species have rows of uncini intercalating to varying degrees, such as T. pappus , T. tantabiddycreekensis and T. leslieae sp. nov. (see below) (see Nogueira et al. in press for more details).

According to Amaral et al. (2006), a single species of Terebella is reported for Brazilian waters, T. pterochaeta Schmarda, 1861 , recorded for the State of São Paulo ( Morgado 1980; Duarte & Nalesso 1996), but this may be a doubtful record, because the type-locality of that species is South Africa. However, two other new species of Terebella were recently described in an unpublished M. Sc. Dissertation ( Alves 2008), and have not yet been formally described.