Pista lizae, Londono-Mesa, 2012

Londoño-Mesa, Mario H., 2012, New Species of Pista Malmgren, 1866 (Polychaeta: Terebellidae) from the Caribbean, Zootaxa 3317 (1), pp. 39-48 : 43-45

Pista lizae sp. nov.

Figs. 2A–M

Material examined: Type material: Holotype ECOSUR 0126 CHA-14 Champoton , (19°22’N 90°45’W), Campeche, Mexico, 16.II.1999 . Paratypes: ECOSUR 0127 CHA-14 (23) Champoton , (19°22’N 90°45’W), Campeche, Mexico, 16.II.1999 . UMML 22.1031 (9) Card Sound , Florida Keys (25°22’N 80°17’W), Florida, USA, 30.XII.1970; 2–5 m depth. Col. J. García-Gómez. USNM 1157000 (3) Card Sound , Florida Keys (25°22’N 80°17’W), Florida, USA, 30.XII.1970; 2–5 m depth. Col. J. García-Gómez. Additional material: Florida: UMML 22 :65 (2) Biscayne Flats, Biscayne Bay , Florida (25°43’N 80°14’W), 8.VI.1936; 1 m depth. Gulf of Mexico: UANL (1) Pajaros Island , Veracruz, 14.IV.2002, P.1. Mexican Caribbean: UQROO (1) Chacmochuk (21°26’30’’N 86°53’49’’W), Northern Yucatan Península , Mexico, E-10, 6.IV.2000. Panama: MCZ 455 B (2) Panama, 29.III.2002 (as Eupolymnia regnans by A. Agassiz) .

Description: Holotype complete, 79 segments, 13 mm long, thorax 4 mm long, 1 mm wide ( Figs 2A–C ). Tentacular membrane short, with smooth edges; two dorsal groups of 5–6 eyespots, brown and rounded; each group almost aligned with branchiae bases. Tentacles short in preserved condition. Upper lip short, square, with ventral edges folded; lower lip long, swollen, triangular, not covered by ventral edge of first lateral lappets. Four pairs of lateral lappets; first on segment 1, longer than upper lip, lateral edges rounded, well developed, with slender margins and swollen bases; ventral edge V-shaped. Second pair reduced, with short lateral edges projecting between first and third lappets; connected to first ventral shield, not well differentiated. Third pair long, wide, rounded, projected and folded laterally, with dorsal margin well developed. Fourth pair the shortest, as a thin edge below third pair, between base of first notopodium and ventral shield. Dorsally, segment 4 with well-developed margin, carrying one long digitate lobe projecting anteriorly ( Fig. 2D ); base triangular, fused to dorsal edges of third pair of lateral lappets. Segments 5 and 6 with a short ventral lappet, almost inconspicuous, connected to ventral shields. Two pairs of nephridial papillae on segments 6 and 7, flattened, placed posterodorsally to notopodium, inside inter-segmental folds. Eighteen ventral shields from segment 2 ( Fig. 2E ); first shield wide, second and third shields curved, thinner; fourth, fifth, sixth and seventh slightly decreasing in size, then of similar size, swollen, separated from each other. Two pairs of branched branchiae on segments 2 and 3; pairs commonly incomplete; medium sized, stalk thick and ringed, distally ending in four secondary zig-zag-shaped stalks, emerging from same point; secondary stalks with dichotomous tips; branchiae on segment 3 with only three secondary stalks. Notopodia spherical, from segment 4; 17 notochaetigers; chaetae of two sizes ( Fig. 2F ), long chaetae lanceolate, symetrically bilimbate distally extended to fine tip ( Fig. 2G ); short chaetae wider in lanceolate region, as long as middle bilimbate region of long chaetae ( Fig. 2H ). Neuropodia from segment 5; uncini from segments 5–10 in single rows; uncini from first four uncinigers ( Figs 2 I-K) MF:3:2–3:1, PP thick, PF short, tapered, with rounded tip; Oc long, slightly convex; Cp with small teeth over very long MF; USr and LSr concave, SrP thick; SrA not seen; AP and AF absent; Bs slightly curved. Uncini from last three single thoracic uncinigers resemble those in double rows. Uncini from segments 11–20 ( Fig. 2L ) in intercalated double rows, face to face; MF:2–3:3:1–2, PP absent; PF weak and thin; Oc long, almost straight; Cp with small teeth over a stout MF; USr and LSr slightly concave, divided by a short, acute SrP; SrA triangular, reaching the MF tip; AP and AF absent; Bs convex. Abdominal uncini in single rows, smaller ( Fig. 2M ); MF:3:3:2–3:2–1, PP absent; PF long, thin; Oc short, concave; Cp with four series of teeth decreasing in size above the MF; Sr slightly concave, SrP and SrA absent; AP long, translucent; AF thin, long. Pygidium with smooth edge.

Staining pattern by methyl green: Tentacles often stain outside and laterally to longitudinal groove. Ventral shields 2–15 stain; first shield in the posterior middle stains deeply; next two shields stain barely; next shield stains completely as a central square. First three pairs of lateral lappets stain deeply only at the base; borders do not stain. Fourth pair of lateral lappets remains pale. Mid-dorsal lobe on segment 4 does not stain. Dorsally, notopodial glandular tissue stains barely, in inverted V, from segment 5 up to end of thorax. Branchiae do not stain. Nephridial papillae do not stain. Pygidial papillae stain deeply.

Variation: This species is considered having small sizes, although no specimens were found gravid; complete specimens have 71–82 segments, 9.0– 13.5 mm long, and thorax 0.7–0.8 mm long, and 0.9–2.0 mm wide, on average, meaning narrow variations. The nephridial papillae could be swollen and emerged on the inter-segmental divisions, as in species of Pista . A complete specimen from Florida has a pygidium with four concentric short rounded papillae.

Discussion: Pista lizae sp. nov., differs from P. vossae sp. nov., and from P. palmata ( Verrill, 1873) , having only one mid-dorsal lobe on segment 4, branchiae with secondary stalks arising alternately from the main stem, eyespots present, and uncini with long posterior process only in the most anterior three uncinigers. Pista lizae sp. nov., differs also from P. cetrata ( Ehlers, 1887) because of the absence of the internal cavity in the third pair of lateral lappets. Finally, even though P. lizae sp. nov., is similar to P. quadrilobata in the presence of eyespots according to Day (1973) and Kritzler (1984), they differ in the absence of mid-dorsal lobe, and the presence of uncini from uncinigers 2 and 3 with long posterior processes, presented by P. quadrilobata .

Finally, P.lizae sp. nov., could be considered a “small-bodied” species since, having 79 segments, and two well visible nephridial papillae on segments 6 and 7, it just reaches 13 mm in length.

Etymology: This species is named in honor of Lizette I. Quan-Young, my beloved girlfriend, for her unconditional company, and for being an excellent, passionate Mexican marine biologist.

Type locality: Champoton, Campeche, Northern Yucatan Peninsula .

Distribution: Type locality, Florida, Eastern Gulf of Mexico, and Atlantic Panamanian. Found from intertidal waters to 3 m depth.

Figures

FIGURE 2. Pista lizae sp. nov. A. Thoracic region in ventral view. B. Thoracic region in lateral view. C. Thoracic region in dorsal view. D. Anterior end in dorsal view. E. Anterior end in ventral view. F. Fascicle of notochaetae from segment 12. G. Long notochaeta from segment 12. H. Short notochaeta from segment 12. I. Uncinus from segment 5. J. Uncinus from segment 6. K. Uncinus from segment 8. L. Uncini from segment 11. M. Uncinus from segment 25. Abbreviations, in alphabetical order: Br, Branchia; DLb, Dorsal Lobe; LL, Lateral Lappet; NeP, Neuropodium; NoP, Notopodium; S, Segment; UpLi, Upper Lip; VS, Ventral Shield. Scale bars: A,B,C: 2 mm; D: 0.75 mm; E: 0.25 mm; F: 0.09 mm; G,H: 0.05 mm; I–M: 0.02 mm.