Volume 53(9):115‑127, 2013 ANATOMY OF PHYLLODINA PERSICA (BIVALVIA: TELLINIDAE), AND ITS FIRST OCCURRENCE IN SOUTHEASTERN BRAZILIAN WATERS 1,2 RODRIGO CESAR MARQUES 2 LUIZ RICARDO L. SIMONE ABSTRACT This study presents a detailed anatomy of a rare Western Atlantic tellin, Phyllodina persica, under a comparative scenario. Some characters are shared with other tellinids such as the large hemipalps compared to gills; gills with outer demibranch with a single lamella absent from the pericardial region; the type‑V stomach associated with the style sac conjoined with the proxi‑ mal intestine, and distal intestine presenting a dorsal and ventral group of loops, separated by the transverse muscle. The stomach presents a laterally enlarged typhlosole, although shallow, without flange in the margins. This feature is not found in other tellinid species. Another noteworthy feature in the stomach is the aperture of both caeca, which are larger than the left pouch aperture, and as wide as the style sac aperture. Furthermore, there is an interesting small process in the anterior hinge, and a pair of oblique protractor muscles placed posteriorly to the anterior foot retractor muscle, being a new type of intrinsic muscle described in bivalves. In addition to anatomy, this study presents the southernmost record of P. persica, expanding its distribution to the southeastern region of Brazil. Key-Words: Tellinidae; Anatomy; Morphology; Phyllodina; Western Atlantic. INTRODUCTION present in the American continents: Phyllodina fluctig‑ era (Dall, 1908) and P. pristiphora (Dall, 1900) from Phyllodina Dall 1900 is a tellinid taxon of rare Mexican to Costa Rica Pacific coasts (Keen, 1971), occurrence, characterized by an elongated oval out- P. persica (Dall & Simpson, 1901) and P. squamifera line, oblique and detached pallial sinus connected to (Deshayes, 1855) in the Western Atlantic, ranging the pallial line by a linear scar and a foliated concen- from North Carolina, USA (Boss, 1969), through Ca- tric sculpture (Boss, 1969). It has traditionally been ribbean, and Brazilian Northeastern Coast (Tenório, considered as a subgenus of Tellina Linné, 1758. Due 1984; Cauquoin, 1967). P. persica, the focus of the to this distinctive characteristics, Phyllodina possibly present paper, is characterized by a more ellipsoid out- constitutes a natural group (Boss, 1966, 1969). Re- line and a sculpture less foliated than P. squamifera and cently this taxon, like of most subgenera belonging P. pristophora, resembling P. fluctigera of the Eastern to Tellina, have been shifted to the genus status (e.g., Pacific, a possible closely allied species (Boss, 1969). Turgeon et al., 2009). Four species of Phyllodina are P. persica presents a very rare record, characterized so 1. Programa de Pós-Graduação em Zoologia, Instituto de Biociências da Universidade de São Paulo. E-mail: [email protected] 2. Museu de Zoologia, Universidade de São Paulo. Caixa Postal 42.494, 04218-970, São Paulo, SP, Brasil. E-mail: [email protected] 116 Marques, R.C. & Simone, L.R.L.: Anatomy of PHYLLODINA PERSICA far by few occurrences from Cuba through the Lesser muscle; pr, foot protractor muscle; ps, septal siphonal Antilles, and the Colombian Caribean. The present muscle; pt, posterior lateral tooth; r, dorsal stomach reported occurrence in northern Rio de Janeiro State ridge; r1, minor dorsal stomach ridge; ra, anterior expands the geographic distribution of the species. All foot retractor muscle; rc, right caecum; rd, radial si- the registers are in depths below 25 m up to 400 m. phonal muscle re, rectum; rg, ring around style sac All of these past registers are constituted only by aperture; rm, esophageal rim; rp, posterior foot retrac- valves, without soft parts preserved. tor muscle; rs1, superior branch of siphonal muscle; Recently, in a marine research study carried out rs2, inferior branch of siphonal muscle; sa, selection by Petrobras S/A, called Habitats Project, a well-pre- area; si, blood sinus; sm, siphonal muscle; sn, sipho- served specimen was dredged from northern Rio de nal nerve; sp, intestine-style sac septum; ss, style sac; Janeiro State. Due to paucity of the Phylodina records, st, stomach; tp, projections around distal siphon as well as the first occurrence of a sample with soft tip; tm, middle transverse muscle; tt, siphonal ten- parts, the assessment of the anatomy of P. persica im- tacle; ty, typhlosole; vc, ventral channel; ve, ventricle; proves considerably the systematics of the taxon, this vg, visceral ganglion; vi, visceral sac; vs, vestibule. being a concern of the present paper in a comparative scenario. DESCRIPTION MATERIAL AND METHODS Phyllodina persica Dall and Simpson 1901 (Figs. 1‑40) The specimen is fixed in Alcohol 70% and dis- sected by standard techniques, immersed in alcohol. Tellina (Arcopagia; Phyllodina) persica: Dall & Simp- Pictures were taken with a digital camera mounted son 1901: 479 (pl. 55, fig. 1). on stereomicroscope and later edited in Corel Photo- Tellina (Arcopagia) persica: McLean, 1951: 94. Paint®. Drawings were done with the aid of a camera Tellina (Eurytellina) persica: Warmke & Abbott, lucida and later edited in Corel Draw®. 1961: 195 (pl. 29, fig. g). Tellina persica: Cauquoin, 1967: 227. Abbreviations in figures and text: aa, anterior adduc- Tellina (Phyllodina) persica: Boss, 1969: 255 (pl. 136, tor muscle; ab, aortic bulb; am, anterior transverse fig. 2); Rios, 1975: 241 (pl. 77, fig. 1157); muscle above stomach; ap, dorsal-posterior appendix; 1994: 271 (pl. 93, fig. 1328); Abbott, 1974 497 bm, branchial muscle; bn, branchial nerve; an, an- (fig. 5646); Díaz & Puyana, 1994: 88 (fig. 219). terior nerve; at, anterior lateral tooth; au, auricle; bt, bifid cardinal tooth; ci, circular siphonal mus- Type locality: Mayaguez, Puerto Rico. cle; cc, cerebral commissure; cg, cerebral ganglion; cm, cruciform muscle; cp, cerebro-pedal connective; Shell (Figs. 1‑3, 6‑11) cs, cruciform to siphonal muscle; ct, ctenidial axis; cv, cerebro-visceral connective; dd, diverticulum; General outline elliptic, elongated. Length de, outer demibranch; dh, dorsal hood; di, inner ~18 mm. Length/height ratio ~1.65. Width/length demibranch; es, excurrent siphon; fl, flap over style ratio ~0.4. Umbo positioned on shell half as mall, sac aperture; fn, pedal nerve; ft, foot; gd, gonoduct; pointed upturned. Anterior margin rounded. Ven- gf, gastric flap; go, gonad; gp, gonopore; gs, gastric tral margin slightly rounded. dorso-posterior margin shield; he, outer hemipalp; hi, inner hemipalp; ig, in- straight. Posterior margin bounded by angles well de- testinal food groove im, intestinal transverse muscle; veloped, rounded. Poorly rostrated. Walls relatively is, incurrent siphon; ki, kidney; lg, ligament; la, lat- thick. Outer surface opaque white, suffused with yel- eral extension of typhlosole; lc, left caecum; le, ex- low close to umbo; inner surface white suffused with ternal mantle lamella; li, internal mantle lamella; red. Ornamentation with commarginal ribs, elevated, lm, middle mantle lamella; lo, longitudinal siphonal laminated, separated by broad sulcus; taller and more muscle; lp, left pouch; lt, laminate cardinal tooth; irregular in posterior and anterior surface than me- mp, pallial muscle; mo, mouth; ne, nephropore; dian; sulcus around six times wider than ribs (Fig. 6). ny, nymph; oe, esophagus; om, oblique protactor Umbonal cavity deep. Cardinal teeth on infraumbo- muscle; pa, posterior adductor muscle; pg, pedal gan- nal region, comprising two teeth in both valves, dis- glion; pl, palp; po, posterior pallial muscle; pp, pa- posed divergently (Figs. 10-11); right cardinal pos- pilla; pn, posterior nerve; pm, posterior transverse terior tooth bifid (Fig. 7: bt); right cardinal anterior Papéis Avulsos de Zoologia, 53(9), 2013 117 tooth laminate (Fig. 7); left cardinal posterior tooth from posterior third to posterior half of dorso-an- laminate (Fig. 8: lt); left cardinal anterior tooth bi- terior margin, with taller elevation in half, turned fid (Fig. 8: bt). Cardinal laminate teeth not reaching dorsally upward (Fig. 10: at); posterior lateral teeth cardinal plate margin (Fig. 9). Anterior and posterior distal, located above posterior adductor scar level, in lateral teeth present in both valves, sockets present in third posterior of dorso-posterior margin, equivalent right valve only; anterior lateral teeth distal, ranging to 30% of anterior lateral teeth length (Fig. 10: pt). FIGURES 1‑11: Shell and anatomic aspects of Phyllodina persica (MZSP 96780): 1, left valve, external view; 2, right valve, internal view; 3, dorsal view; 4, right view, valves and part of mantle removed; 5, detail of right mantle edge, internal view (gray arrow = thin muscles; white arrow = thick muscles); 6, detail of commarginal ornamentation on posterior surface of left valve; 7, right cardinal hinge tooth, inferior view; 8, left cardinal hinge tooth, inferior view; 9, right cardinal tooth and process anterior hinge (white arrow); 10, right hinge; 11, left hinge. Scales bar = 1.5 mm. 118 Marques, R.C. & Simone, L.R.L.: Anatomy of PHYLLODINA PERSICA Small process on third posterior between cardinal bundles, equally spaced (Fig. 5: gray arrow) and thick teeth and anterior lateral teeth (Fig. 9). Ligament seat- bundles, about three times thickness of thin bundles, ed on nymph, brown, ranging from posterior side of ventrally branched, spaced at 4 thin bundles (Fig. 5: umbo to half of dorso-posterior margin (Figs. 10-11). white arrow). Siphonal muscle ranging from proximal Nymph wall shorter than lateral teeth, parallel to mar- aperture of siphons (Fig. 29) to lateral median region gin. Muscle scars well visible; both adductor muscle of shell, spreading in numerous fibers (Fig. 12); in- scars of equivalent size, each scar occupying ~10% of sertion area fan-like, antero-posteriorly elongated valve inner surface. Anterior adductor muscle scars el- (Fig. 30); origin divided in two bundles of same thick- liptical, dorso-ventrally elongated. Posterior adductor ness (Fig. 29: rs1), connected to proximal excurrent muscle scars rounded. Pallial line parallel and at 1/10 aperture, and rs2, below rs1, connected to proximal of shell height distant from margin.