Pista Malmgren, 1866

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 : 32

Genus Pista Malmgren, 1866

Type species: Amphitrite cristata Müller, 1776 , by original designation.

Diagnosis. Usually two or three pairs of branchiae, on segments 2–3 or 2–4, a few species with a single pair of branchiae on segment 2; branchiae usually with long basal stem. Lobes present on segments 1–4, sometimes extending posteriorly for some more segments. Usually 17 pairs of notopodia, beginning from segment 4, with broadly-winged notochaetae. Neuropodia from segment 5, with long-handled uncini on some anterior segments, frequently until end of notopodia (segment 20), then short-handled until end of body; long handle originating exclusively from heel; uncini in double rows, usually in a completely intercalated arrangement, on segments 11–20. Nephridial papillae usually on segment 3, dorsally to insertion of lobes on segment 3, genital papillae usually on segments 6–7, posterior to notopodia and dorsally aligned to them.

Remarks. Pista is a large genus, reported worldwide, characterized by the presence of lobes on anterior segments, long-handled uncini occurring for variable number of segments on the region with biramous parapodia, and 17 pairs of notopodia with broadly-winged notochaetae.

The morphology of lobes in this group, especially in regards to the shape of lobes on segment 1, is important in distinguishing species. Some species, including the type-species, P. cristata ( Müller, 1776) , have low ventro-lateral lobes on segment 1, just around the lower lip and not extending anteriorly and covering the anterior end, while other species, including the species described in this paper, have larger lobes on segment 1, extending anteriorly and laterally covering the anterior end, connected to each other by lower mid-ventral membrane partially exposing the lower lip.

Most species of Pista have two pairs of branchiae, but a few species have three pairs, such as P. cretacea ( Grube, 1860) , discussed below. Some species have been described as having a single pair of branchiae, however most of these taxa also have short-handled uncini throughout and therefore they should be transferred to the genus Pistella Hartmann-Schröder, 1996 ; the exception is Pista sp. B sensu Kritzler, 1984, discussed below.

The shape of branchiae also shows great variability from plume-shape to branching branchiae, usually with long basal stem (see Hutchings & Glasby 1988).

The number of pairs of notopodia, and the segment on which they start also exhibit some intrageneric variation. Most species have 17 pairs of notopodia, beginning from segment 4, but P. quadrilobata ( Augener, 1918) has notopodia on segments 4–21, and Pista sp. A sensu Kritzler, 1984 has notopodia on segments 4–18.

In Brazil, four species of Pista have been recorded prior to this study, P. corrientis McIntosh, 1885 , occurring from the state of Rio Grande do Sul to Rio de Janeiro ( Lana 1981; Blankensteyn 1988; Nogueira 2000; Alves 2008) and in Sergipe ( Santos et al. 1994), P. cretacea , only known from the State of São Paulo, P. cristata , from the State of Rio Grande do Sul to Alagoas, and P. herpini Fauvel, 1928 , from the State of São Paulo to Rio de Janeiro ( Amaral et al. 2006). Except for P. corrientis , type locality off Argentina, the other three species were originally described from localities distant from Brazil and their occurrences in the country are unlikely, however it is not possible to check these identifications, because the Brazilian specimens are not lodged in any museum.

On the other hand, although P. corrientis was described from an area close to Brazil, off the mouth of Rio de la Plata, the holotype was collected from ~ 1100 m deep (600 fathoms) and all recent material is from the intertidal zone to shallow water. In order to confirm that identification, the holotype of P. corrientis was examined and the Brazilian material belongs to a separate species, still undescribed and treated herein as Pista sp. The redescription of P.corrientis and the description of Pista sp. are beyond the scope of the present paper and will be published elsewhere (Nogueira at al. in prep.).