Pista alonsae, Santos & Nogueira & Fukuda & Christoffersen, 2010

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: 33-42

publication ID

http://doi.org/ 10.11646/zootaxa.2389.1.1

persistent identifier

http://treatment.plazi.org/id/8C6287D6-4330-FFCC-FF16-2F4239F8B130

treatment provided by

Felipe

scientific name

Pista alonsae
status

sp. nov.

Pista alonsae   sp. nov.

( Figs. 16–19 View FIGURE 16 View FIGURE 17 View FIGURE 18 View FIGURE 19 ; Table 4)

Material examined. Type material. Holotype and paratypes 1–4 coll. Sta. 8 (05°04’01.4”S 36°27’31.3”W), 9 Nov 2007; holotype MZUSP 01036, paratype 1 CIPY-POLY-1396, paratype 2 CIPY-POLY-1397, paratype 3 CIPY-POLY-1398, paratype 4 LACM-AHF POLY 2263. Paratype 5 LACM-AHF POLY 2258, coll. Sta. 12 (05°04’57.9”S 36°28’31.5”W), 10 Nov 2007. Paratypes 6–7 coll. Sta. 10 (05°04'30.3”S 36°27'53.9”W), 9 Nov 2007; paratype 6 MZUSP 01037, paratype 7 CIPY-POLY-1399. Paratypes 8–9 coll. Sta. 5 (05°04’44.7”S 36°26’33.5”W), 9 Nov 2007; paratype 8 MZUSP 01038, paratype 9 ZMUC-POL-2109. For more information on each specimen of type-series see Table 4.

Comparative material examined. Pista cetrata   ( Ehlers, 1887, as Terebella cetrata   ). Holotype ( MCZ 834 View Materials ), coll. Expedition Blake, USA, Florida, Key West, by A. Agassiz, 2–4 m, 1877–1878; incomplete spec., in relatively good state of preservation; slides: notochaetae from segment 18; neurochaetae from segments 6, 13, 23, 61.  

Pista corrientis McIntosh, 1885   . Holotype ( BMNH 1885.12.1.348): coll. Challenger Exp., South Atlantic   GoogleMaps , Argentina, off the mouth of Rio de la Plata (37 o 17’S 53 o 52’W), in sea bottom with green sand, ~ 1100 m (600 ft), 14 Feb 1876; complete spec., in poor state of preservation, but important characters still visible; all notochaetae shaved off; slides: neurochaetae from segments 9, 19, 23 and 83.

Pista cristata ( Müller, 1776)   . Non-type material. ZMUC Pol 707: coll. R/V “Ophelia” dredge 72, North Atlantic Ocean, Denmark, off Laesø, W edge of Kummelbankens, by C. Nielsen, 39–43 m, stones and mud, 7 Jul 1960; 2 specs in relatively good state of preservation, all posteriorly incomplete; slides: notochaetae from segments 6 and 19; neurochaetae from segments 5–11, 14 and anterior part of region after notopodia terminate. ZMUC Pol 2054: coll. North Atlantic Ocean, Denmark, Frederikshavn, by H. Ditlevsen, soft bottom, 15 Jul 1927; 3 specs in relatively good state of preservation, all posteriorly incomplete and partially inside the tubes. ZMUC Pol 2055: coll. Biological field course, North Atlantic Ocean, Denmark, Laesø Rende, 30 m, 29 Jul 1947; 3 specs in poor state of preservation, 2 of them inside the tubes. ZMUC Pol 2056: coll. Biological field course, North Atlantic Ocean, Denmark, Frederikshavn, 1 Aug 1947; 6 specs in relatively good state of preservation, 4 of them partially inside the tubes.

Pista palmata   ( Verrill, 1873, as Scionopsis palmata   ). Non-type material. USNM 090608: coll. North Atlantic Ocean, Gulf of Mexico, USA, Texas, off Port Isabel (26 o 10’N 97 o 08’W), BLM, Sta IV-4, ves: STOCS, winter 1977, 15 m; incomplete spec., in relatively poor state of preservation. USNM 090611: coll. North Atlantic Ocean , Gulf of Mexico , USA, Texas, off Port Isabel (26 o 10’00”N 97 o 08’00”W), BLM, Sta S- 53, ves: IXTOC, Dec 1980, 15 m; fragment in very poor state of preservation. USNM 090610: coll. North Atlantic Ocean , Gulf of Mexico , USA, Texas, off Port Isabel (26 o 10’N 97 o 08’W), BLM, Sta IV-4, ves: STOCS, fall 1983, 15 m; 2 specs, one complete and tiny, other incomplete, both in very poor state of preservation; slides: spec. USNM 090610 (incomplete spec.): notochaetae from segments 6 and 18; neurochaetae from segments 5, 11, 27 GoogleMaps   .

Pista sombreriana McIntosh, 1885   . Holotype ( BMNH 1885. 12.1.344): coll. Challenger Exp., North Atlantic Ocean, Caribbean, off Sombrero and St. Thomas; incomplete spec. in very poor state of preservation, in three pieces, anterior piece further cut in two halves along longitudinal midline; slides: notochaetae from segment 14; neurochaetae from segments 6, posterior part of region with biramous parapodia and anterior part of region after notopodia terminate (the state of preservation of the specimen prevents from counting the segments).

Pista sp.   : Brazil, southeastern continental shelf, off State   GoogleMaps of Paraná: AM W34750 View Materials : coll. 26°22'S 48°19'08”W, 49 m, sand with mud, 3 Nov 1985; 1 spec., mounted on SEM stub. MCEM-BPO 271: coll. 24°16'S 46°01'02”W, 45 m, sand, 26 Mar 1984; 2 specs. MCEM–BPO 273: coll. 26°22'S 48°19'08”W, 49 m, sand with mud, 17 Mar 1984; 2 specs. MCEM–BPO 274: coll. 25°04'S 46°26'00”W, 65 m, sand with mud, 22 Mar 1984; 1 spec.; slides: notochaetae from segments 5 and 14; neurochaetae from segments 5–14 and from region after notopodia terminate. MCEM–BPO 276: coll. 26°22'S 48°19'08”W, 49 m, sand with mud, 3 Nov 1985; 2 specs. MCEM–BPO 277: coll. 25°55'S 47°52'03”W, 49 m, sand with mud, 4 Nov 1985; 1 spec. MCEM–BPO 278: coll. 25°04'S 46°26'00”W, 65 m, sand with mud, 13 Nov 1985; 1 spec. State of Paraná, Paranaguá Bay : MCEM–BPO 282: coll. 25°33'S 48°25’W, 18 m, sand with gravel and mud, 27 Feb 1986; 2 specs GoogleMaps   . Brazil, southeastern continental shelf, off State of São Paulo, Project “REVIZEE”: coll. 24°46'S 45°11'W, 99 m, 12 Jan 1998; 1 spec. GoogleMaps   coll. 25°11'S 47°08'W, 157 m, 16 Dec 1997; 5 specs. State of São Paulo, Santos, Ilha das Palmas (24°00'S 46 ° 19'W), intertidal, on rocky shore, Project “Biodiversidade de Anelídeos Poliquetas em Costões Rochosos ao Longo do Estado de São Paulo ”: coll. 6 Mar 2004, 1 spec. GoogleMaps   ; coll. 5 Oct 2005, 1 spec. State of São Paulo, São Sebastião, offshore, Project “BIOTA/FAPESP/Benthic Marine Biodiversity in the State of São Paulo ”: coll. 23°42'S 45°11'W, 25.2 m, 13 Feb 2001, 2 specs; coll. 23°46'S 45°10'W, 39.3 m, 23 Jun 2001, 1 spec. GoogleMaps   ; São Sebastião, Praia da Baleia (23°46'S 45°39'W), intertidal, on rocky shore, Project “Biodiversidade de Anelídeos Poliquetas em Costões Rochosos ao Longo do Estado de São Paulo ”: coll. 23 Jul 2005, 1 spec. GoogleMaps   ; coll. 17 Out 2005, 1 spec.   ; São Sebastião, Praia de São Francisco (23°44'S 45°24'W), intertidal, on rocky shore, Project “Biodiversidade de Anelídeos Poliquetas em Costões Rochosos ao Longo do Estado de São Paulo ”: coll. 24 Jul 2005, 1 spec. GoogleMaps   State of São Paulo, Caraguatatuba, offshore, Project “BIOTA/FAPESP/Benthic Marine Biodiversity in the State of São Paulo ”: coll. 23°42'S 45°11'W, 25 m, 22 Apr 2001, 1 spec. GoogleMaps   ; coll. 23°43'S 45°18'W, 11 m, 27 Nov 2002, 1 spec.; coll. 23°53'S 45°30'W, 25 m, 15 Feb 2001, 1 spec.; Praia Martim de Sá (23°37'S 45°22'W), shallow water, in algae on rocky shore, Project “BIOTA/FAPESP/Benthic Marine Biodiversity in the State of São Paulo ”: 16 Mar 2001, 1 spec. GoogleMaps   State of São Paulo, Ubatuba, offshore, Project “BIOTA/FAPESP/Benthic Marine Biodiversity in the State of São Paulo ”: coll. 23°25'S 44°46'W, 35 m, 17 Mar 2001, 8 specs; coll. 23°25'S 44°46'W, 35 m, 10 Jun 2001, 1 spec. GoogleMaps   ; coll. 23°31'S 45°05'W, 8 m, 21 Mar 2002, 1 spec.; coll. 23°32'S 45°05'W, 15.5 m, 23 Mar 2002, 1 spec.; coll. 23°33'S 45°04'W, 23.4 m, 23 Mar 2002, 1 spec.; coll. 23°48'S 45°10'W, 30.1 m, 20 May 2002, 1 spec.; Ubatuba, Praia de Picinguaba (23°22'S 44°50'W), shallow water, in algae on rocky shore, Project “BIOTA/ FAPESP/Benthic Marine Biodiversity in the State of São Paulo ”: coll. 8 Jun 2001, 6 specs; coll. 8 Oct 2001, 1 spec. GoogleMaps   ; coll. 18 Oct 2001, 2 specs. Brazil, southeastern continental shelf, off State of Rio de Janeiro, Project “REVIZEE”: coll. 21°51'S 40°07'W, 110 m, 2 Mar 1998, 1 spec. GoogleMaps   ; coll. 24°02'S 43°30'W, 147 m, 14 Feb 1998, 23 specs.

Description. Thick tube, mucous, with sand, coarse stones and fragments of shells embedded ( Fig. 16A View FIGURE 16 ). All specimens incomplete, holotype longest specimen examined, 77 mm long, ~ 2 mm wide, with ~106 segments ( Table 4); all specimens with short buccal tentacles, up to 5 (3.5) mm long. Preserved body light brown, with darker pigmentation on lobes and around neuropodia ( Fig. 16A–J View FIGURE 16 ). Body not remarkably inflated dorsally ( Figs 16A, C–E, G–I View FIGURE 16 ; 17A–C, E, I–J View FIGURE 17 ); anterior segments compact, about same length, segments progressively longer from segment 8 until end of notopodia, more evident from segments 13–14 ( Figs 16A–I View FIGURE 16 ; 17A–F, H–J View FIGURE 17 ). Ventral shields on segments 2–16, shields smooth, rectangular, widest shield on segment 2, progressively narrower until segment 8, then about same width until segment 16; shields progressively longer from segment 6 ( Figs 16A–B, F View FIGURE 16 ; 17B, D, F, H, J View FIGURE 17 ); after segment 16 shields substituted by mid-ventral groove extending posteriorly. Prostomium at base of upper lip, laterally covered by lobes on segment 1 ( Figs 16A–J View FIGURE 16 ; 17A–B, D–F, H–J View FIGURE 17 ); distal part forming shelf-like process from which buccal tentacles originate; eyespots on basal part of prostomium absent. Peristomium restricted to lips; upper lip short, distinctly wider than long; lower lip short, cushion-like, partially covered by lobes on segment 1 ( Figs 16F, J View FIGURE 16 ; 17D, H View FIGURE 17 ). Segment 1 narrow, with one pair of large, distally rounded lobes originating dorso-laterally, extending anteriorly and ventrally, covering the anterior end, connected to each other by lower mid-ventral membrane, partially exposing lower lip ( Figs 16A–J View FIGURE 16 ; 17A–B, D–F, H–J View FIGURE 17 ). Segment 2 dorsally and laterally short, longer ventrally, with one pair of short and rounded ventro-lateral lobes, connected to each other by low membrane across ventrum ( Figs 16B, D–G, J View FIGURE 16 ; 17B, D–F, H, J View FIGURE 17 ). Segment 3 with one pair of large, distally rounded lobes originating close to dorsal midline, with deep dorso-lateral indentation dividing lobes into two rounded parts, and terminating ventro-laterally at level of lateral margins of ventral shields, far beyond level of ventral edge of neuropodia ( Figs 16A–J View FIGURE 16 ; 17A–F, H–J View FIGURE 17 ). Segment 4 with short lateral lobes as thin flaps ( Figs 16A–J View FIGURE 16 ; 17A– F, H–J View FIGURE 17 ); segments 5–6 with short ventro-lateral lobes, as low flaps between ventral shields and neuropodia ( Figs 16B–G View FIGURE 16 ; 17A–B, D–F, H–J View FIGURE 17 ). Two pairs of branchiae on segments 2–3, with long basal stem and secondary branches originating all at same level and similar in length ( Figs 16A–I View FIGURE 16 ; 17A–F, H–J View FIGURE 17 ); pairs of branchiae vertically aligned. Seventeen pairs of notopodia, starting from segment 4 and extending until segment 20, all similar in size; notopodia of segments 4–8 inserted progressively more laterally, then vertically aligned ( Figs 16A, C–E, G–I View FIGURE 16 ; 17A–C, E–F, I–J View FIGURE 17 ). Broadly-winged notochaetae on both tiers, wing basally bulbous and distinctly broader on one margin, notochaetae on posterior tier with wing starting from mid-length of chaetae ( Figs 18A–B View FIGURE 18 ; 19A–B View FIGURE 19 ); anterior notopodia with notochaetae on posterior tier about twice as long as those on anterior tier ( Figs 18A View FIGURE 18 ; 19A View FIGURE 19 ), posterior notopodia with notochaetae on posterior tier slightly longer than those on anterior tier ( Fig. 18B View FIGURE 18 ). Neuropodia starting from segment 5, as low rectangular ridges slightly raised from surface of the body until segment on which notopodia terminate ( Figs 16A–I View FIGURE 16 ; 17A– J View FIGURE 17 ), as raised pinnules thereafter, situated laterally on body, well separated from mid-ventral groove ( Fig. 17G View FIGURE 17 ), with short dorsal papilla ( Figs 17G View FIGURE 17 , 19J View FIGURE 19 ) and internal neuropodial shafts. Long-handled uncini present until segment on which notopodia terminate, with thin handle as an extension of heel, originating from lighter, less chitinized lower part of the base ( Fig. 18C–F View FIGURE 18 ); uncini on region with biramous parapodia with distally rounded prow, downwardly directed process present, dorsal button situated at mid-length between base of main fang and tip of prow, and crest with 3–4 rows of secondary teeth ( Figs 18C–F View FIGURE 18 ; 19C–F View FIGURE 19 ); uncini arranged in completely intercalated double rows from segment 11 until segment on which notopodia terminate ( Figs 18E View FIGURE 18 ; 19E–F View FIGURE 19 ); after notopodia terminate, uncini similar to anterior ones, but short-handled and with inconspicuous dorsal button ( Figs 18G–H View FIGURE 18 ; 19G–J View FIGURE 19 ). One pair of short nephridial papillae on segment 3, inserted dorsally to bases of lobes, between bases of lobes and bases of branchial stalks; genital papillae situated posterior and dorsally to notopodia on segments 6–7 ( Figs 16H–I View FIGURE 16 ; 17A, C, E, I View FIGURE 17 ). Pygidium unknown.

Variation. The specimens examined are all posteriorly incomplete and poorly preserved from the beginning of the region after notopodia terminate. The only character which shows variation among the material examined is the size of branchiae. In most specimens, at least one of the branchiae is missing and frequently they are different in size from one side of the body to the other, within the same pair. Most specimens have the branchiae of the first pair longer than those of the second pair, but the opposite occurs in some specimens. This possibly indicates that branchiae are easily lost and regenerated in this species.

Remarks. Pista alonsae   sp. nov., belongs to the group of species of Pista   with large lobes on segment 1, extending anteriorly and laterally covering the anterior end, as discussed above. Of the four other species of Pista   reported for the Brazilian coast, P. cristata ( Müller, 1776)   and P. cretacea ( Grube, 1860)   have short lobes on segment 1, just around the lower lip and not covering the anterior end, while Pista sp.   and P.herpini Fauvel, 1928   have lobes on segment 1 as those of P.alonsae   sp. nov.

Pista cristata   was originally described from Norway and its occurrence in Brazil is doubtful, however this species has been recorded worldwide ( Moore 1903; Fauvel 1927; Hartman 1945, 1965, 1966; Imajima & Hartman, 1964; Day, 1967) and is certainly a complex of sibling species. Pista cristata   has been recorded for a long extension along the Brazilian coast, from the State of Rio Grande do Sul to Alagoas ( Nonato & Luna 1970; Nonato 1973; Rullier & Amoureux 1979; Blankensteyn 1988). In addition to the different morphology of the lobes on segment 1, P. cristata   differs from P.alonsae   sp. nov., in having plume-shaped branchiae, with filaments originating in a spiral around basal stem, segment 2 with thickened anterior margin all around, forming a low collar completely encircling the body, and with one pair of longer and more laterally placed ventro-lateral lobes, and segment 3 with shorter lateral lobes and a mid-dorsal rectangular crest from which branchiae originate at each upper corner, while P.alonsae   sp. nov., has branching branchiae, with all branches originating at same level, segment 2 without thickened anterior margins encircling the body, especially dorsally, and with shorter and more ventrally placed pair of lobes, and segment 3 with larger lobes almost reaching dorsal midline, divided into two parts by dorso-lateral indentation, a mid-dorsal crest is absent.

.

Pista cretacea   was originally described from the Mediterranean. In Brazil, the only record for this species was provided in a thesis focused on ecological aspects, carried out on a bay off the State of São Paulo ( Forneris 1969); a complete description of Brazilian specimens was not provided and material was not deposited in any collection. In addition to the different morphology of the lobes on segment 1, P. cretacea   , according to the redescription by Fauvel (1927), differs from P. alonsae   sp. nov., in being a shorter and wider species, up to 25 mm long and 6 mm wide, and in having distinctly shorter lobes on segment 3, absence of lobes on segment 4, three pairs of branchiae, double rows of uncini in a partially intercalated arrangement, and nephridial and genital papillae on segments 3–15. In contrast, the holotype of P. alonsae   sp. nov., which is the longest specimen examined, is posteriorly incomplete and is 77 mm in length and around 2 mm in width; in addition, P. alonsae   sp. nov., has short lateral lobes on segment 4 as thin flaps, two pairs of branchiae, double rows of uncini in a completely intercalated arrangement, and nephridial and genital papillae only present on segments 3 and 6–7.

Pista herpini   was originally described from India ( Fauvel 1928). In Brazil, this species has been recorded from the States of São Paulo ( Morgado 1980; Morgado & Amaral 1989) and Rio de Janeiro ( Attolini 1997). Similarly to P. cretacea   , P. herpini   , according to the original description ( Fauvel 1928), differs from P. alonsae   sp. nov., in being a smaller species, reaching 25 mm in length, in not having lobes on segment 4, and in only having long-handled uncini on segments 5–6, while P. alonsae   sp. nov., has long-handled uncini on segments 5–20. Moreover, it is unclear whether Fauvel (1928) examined mature specimens or not, because he said genital papillae were not visible in his material, although he examined many specimens. In the case of P. alonsae   sp. nov., genital papillae are reduced, sometimes inconspicuous in immature specimens, but conspicuous in mature worms.

Pista sp.   is a common species in south and southeastern Brazil and it is morphologically very similar to P. alonsae   sp. nov. This species occurs along the Brazilian coast from the states of Rio Grande do Sul to Rio de Janeiro and in Sergipe, however, although it has been described in several unpublished M. Sc. Dissertations and Ph. D. Thesis ( Lana 1981; Blankensteyn 1988; Nogueira 2000; Alves 2008), a full description including most characters presently considered useful for the taxonomy of the group has not been formally published. In addition, this species has always been identified in those studies as Pista corrientis McIntosh, 1885   , but, as said above, the study of the holotype of the latter species showed they are different taxa. A formal description of Pista sp.   and a redescription of the holotype of Pista corrientis   will be provided soon (Nogueira et al. in prep.), but it is important to discuss here the differences between Pista sp.   and P. alonsae   sp. nov., especially because Pista sp.   is more similar to P. alonsae   sp. nov., than any of the other species of Pista   occurring in Brazil. Pista sp.   differs from P. alonsae   sp. nov., in having lobes on segment 3 not dorso-laterally indented and terminating dorsally more separated from each other, ventral shields on segments 2–20, anterior uncini with 5 rows of secondary teeth, long-handled uncini only present on segments 5–10, with more strongly chitinized handle, and larger nephridial papillae on segment 3, while P. alonsae   sp. nov., has ventral shields on segments 2–16, long-handled uncini on segments 5–20 and uncini with 4 rows of secondary teeth throughout.

On the other hand, the holotype of Pista corrientis   differs from P.alonsae   sp. nov., in having shorter lobes on segment 1, not covering the anterior end, shorter, not dorso-laterally indented lobes on segment 3, originating at level of notopodia of segment 4 and terminating at level of ventral edge of uncinial tori, well separated from ventral shields, ventral shields on segments 2–20, and nephridial papillae on segment 3 inserted dorsally to bases of branchial stalks, while P. alonsae   sp. nov., has larger lobes on segment 3, originating close to dorsal midline and terminating at level of lateral margins of ventral shields, and nephridial papillae on segment 3 inserted between bases of lobes and bases of branchial stalks.

In regards to the species of Pista   occurring in the Caribbean, Kritzler (1984) listed six species for the Gulf of Mexico, P. cristata   , P. fasciata ( Grube, 1870)   , P. palmata ( Verrill, 1873)   , P. quadrilobata ( Augener, 1918)   , and two undescribed species, Pista sp. A   and B, and Salazar-Vallejo (1996) listed two additional species, P. papillosa ( Tourtellote & Kritzler, 1988)   and P. sombreriana McIntosh, 1885   . However, P. papillosa   has a single pair of branchiae on segment 2 and short-handled uncini throughout (Tourtellotte & Kritzler 1988) and therefore it belongs to the genus Pistella Hartmann-Schröder, 1996   , rather than to Pista   . On the other hand, as said above, the study of the holotype of Terebella cetrata Ehlers, 1887   demonstrated that this species belongs to Pista   rather then to Nicolea   , as said by Hartman (1959).

Of those species, P. cristata   , P. sombreriana   and Pista sp. B   sensu Kritzler, 1984 have short ventral lobes on segment 1, while the other species have lobes on segment 1 originating dorso-laterally and extending anteriorly, similar to those of P. alonsae   sp. nov., although in P. fasciata   they are not long enough to cover the anterior end laterally.

Pista cetrata   differs from P. alonsae   sp. nov., in having distally straight, not dorso-laterally indented lobes on segment 3, segment 4 with, in addition to the pair of lateral flaps, one pair of dorso-lateral, distally pointed triangular lobes covering dorsal bases of lobes of segment 3, connected to each other by thick flap across dorsum, forming mid-dorsal pocket, and long-handled uncini only occurring on segments 5–10.

The differences between P. cristata   and P. alonsae   sp. nov., were discussed above. In addition to the difference on the lobes on segment 1, P. fasciata   , according to the redescription by Kritzler (1984), differs from P. alonsae   sp. nov., in having prostomial eyespots, branchiae with shorter basal stems, with secondary branches originating and terminating at different levels, absence of ventro-lateral lobes on segment 2, segment 3 with distinctly shorter lobes, probably not dorso-laterally indented, and narrowly-winged notochaetae. In contrast, P. alonsae   sp. nov., lacks prostomial eyespots, has ventro-lateral lobes on segment 2 and has notochaetae with broad, basally bulbous wing on one margin.

Pista palmata   differs from P. alonsae   sp. nov., in having lobes on segment 3 not dorso-laterally indented, connected to each other by lower mid-dorsal lobe, arborescent branchiae, ventral shields on segments 2–20 and long-handled uncini with distinctly thicker handle, while in P. alonsae   sp. nov., in addition to the lobes on segment 3 having deep dorso-lateral indentation, branchiae having secondary branches originating and terminating at same levels, and the uncini on anterior segments having thinner handles, such mid-dorsal lobe on segment 3 is absent.

As said above, the holotype of P. sombreriana   is in poor state of preservation, but most of the characters important to the taxonomy of the group are still visible. The holotype of P. sombreriana   has a ventral lobe on segment 1, below the lower lip, short ventro-lateral lobes on segments 2–4, as low flaps of tissue originating progressively more laterally, and long-handled uncini throughout the region with biramous parapodia. The morphology of the lobes of the holotype of Pista sombreriana   is in agreement with the diagnoses of several genera, but not Pista   , which always has much longer lobes. The presence of long-handled uncini on anterior segments, associated with the morphology of the lobes indicate that this taxon actually belongs to Lanicides Hessle, 1917   .

Pista quadrilobata   , according to Kritzler (1984), is also a smaller species than P. alonsae   sp. nov., reported to reach 35 mm in length. In addition, this species has prostomial eyespots, arborescent branchiae, ventral shields extending to segments 18–20, lobes on segment 3 not dorso-laterally indented, notopodia present on segments 4–21, and long-handled uncini only on segments 5–7. In contrast, in addition to what was said above, P. alonsae   sp. nov., has notopodia on segments 4–20, as occurs in nearly all species of this genus.

Pista sp. A   sensu Kritzler, 1984 differs from P. alonsae   sp. nov., in having lobes on segment 3 not dorsolaterally indented, ventral shields extending to segment 18, notopodia on segments 4–18, long-handled uncini only present on segment 5 and arrangement of double rows of uncini gradually changing from beak-to-beak to back-to-back, on last 2–3 segments of the region with biramous parapodia ( Kritzler 1984).

Finally, Pista sp. B   sensu Kritzler, 1984 does not have lobes of any type on segment 1, has upper lip and prostomium with a mid-dorsal cleft, a single pair of branchiae, notochaetae with broad limbation on both margins, and long-handled uncini only present on segments 5–9, while P.alonsae   sp. nov., in addition to what was said above, lacks such mid-dorsal cleft on prostomium and upper lip.

Etymology. We dedicate this species to Dr Carmen Alonso Samiguel, coordinator of the CIPY, who organized the expedition to RDSPT and participated on the collection of all material from RDSPT examined for the present study.

Kingdom

Animalia

Phylum

Annelida

Class

Polychaeta

Order

Terebellida

Family

Terebellidae

Genus

Pista