Type material.

Holotype MZSP 105740 (37.3 mm × 38.2 mm). Paratypes: MZSP 91745, 4 specimens, from type locality. São Paulo state; São Sebastião, Therezinha wreck, 23°54'26"S, 45°27'57"W, 10 m (col. 20.i.2012), MZSP 103766, 2 specimens; Alcatrazes Archipelago, Farol Island, 24°05'44.7"S, 45°42'08.0"W, 6–9 m (coll. 05.x.2011), MZSP 102223, 7 specimens, MNRJ 30603, 1 specimen, MOFURG 51661, 1 specimen; Ilhabela, Saco do Eustáquio, 23°50'11"S, 45°14'21"W, 12 m (col. 09.i.2012), MZSP 105118, 1 specimen; Vitória Island, Saco do Paiá, 23°44.658'S, 45°01.343'W, 6–9 m (15.v.2012), MZSP 105660, 4 specimens, MNRJ 30602, 1 specimen, MOFURG 51662, 1 specimen.

Type locality.

Brazil, Rio de Janeiro state, Angra dos Reis, Jorge Grego Island, 23°13'S, 44°08'W, 5–7 m (col. 08–09.viii.2009).

Etymology.

Reference to the Ecological Station (Esec) Tupinambás for expeditions along the southeastern coast of Brazil and is an arbitrary combination of letters.

Diagnosis.

Shell reaching 38 mm in height, with sharply suprasutural carina starting on the third whorl and forming a large peripheral rounded keel. Umbilicus deep, white, funnel-shaped, narrow (5% to 10% of maximum shell width). Base convex.

Description.

Shell (Figs 1–9, 16). Attaining 37.6 mm × 38.2 mm; depressed trochoid; 8 whorls, slightly convex. Sharp suprasutural carina starting on third whorl and forming peripheral rounded keel. Basic color of shell pale or tawny brown to pinkish-brown with white and dark red to purple spots and axial flammules, especially on periphery; apex purple; base with numerous white dots on beads. Protoconch (Figs 9, 16) of 0.75 whorls, sculptured with tiny pustules. Transition to teleoconch marked by a weak terminal varix. Teleoconch sculptured by beaded spiral cords (beads crowded and rounded), with one or two smaller intercalary beaded spiral cords between, without a pattern. About 20 beaded cords on the last whorl. Cords on the body whorls becoming remarkably narrower towards periphery. First three whorls of teleoconch with weak axial riblets. First whorl with about 15 axial riblets and two weakly spiral cords that produce reticulate sculpture at their intersections (Fig. 16). The spiral cords become stronger starting on the second whorl. Base convex (flattened in juveniles), with about 15 cords between umbilicus and periphery. Cords equal in size and smoother than that of the teleoconch. Spire angle ~80º. Aperture subquadrate, with base round in adults but flat in juveniles; outer lip at ~55º angle from base. Columella truncated, heavily arched, thickened, white, terminating in a rounded denticle. Umbilicus deep, white, funnel-shaped, 5% to 10% of maximum shell width.

Head-foot (Figs 29–30, 32). Total length two whorls. Head rounded located approximately at anterior end of head-foot. Snout reddish, wide, cylindrical; distal end slightly wider than base; dorsal surface papillated, with short, rounded and white papillae; distal surface folded. Outer lips with pseudoproboscis (Fig. 32: pb). Mouth circular, located in middle of ventral surface of snout. Cephalic lappets absent. Cephalic tentacles usually twice larger than snout, sometimes asymmetrical, reddish, dorsoventrally flattened, grooved, narrowing gradually up to lightly pointed tip. Ommatophores located at outer base of cephalic tentacles, ~1/3 of tentacles’ length. Eyes dark and round, at tip of ommatophores.

Foot thick, occupying ~3/4 of total head-foot length; reddish colored; dorsal region covered by numerous white papillae. Epipodium (Figs 29–30) surrounding lateral-dorsal region of foot, equidistant from sole and base of ommatophore. Opercular pad (Fig. 29: opd) located in the middle of dorsal region; rounded, edge free on posterior area; posterior end with several V-shaped furrows, apex pointed toward posterior end and pair of longitudinal furrows on median line. Furrow of pedal glands present along entire anterior edge of foot (Fig. 30: pg); single aperture of pedal glands located in median region of furrow. Anterior third of epipodium formed by well-developed neck lobes (Figs 29–30: nl); left neck lobe smooth, right neck lobe with fine digitations. Remaining 2/3 of epipodium relatively low, thick; 4 pairs of slender tentacles inserted at its distal edge on each side and located approximately equidistant, well away from each other, symmetrical on both sides, becoming shorter towards posterior end. Epipodial sense organ present at base of each tentacle, indistinguishable from the foot papillae on the lateral sides of the foot. Pair of columellar muscles thick, ~¼ whorl, fused with each other in median line.

Operculum. About 13 mm in diameter, closing entire aperture. Yellowish gold, thin, corneous, multispiral, nucleus central. Inner side convex, outer side concave.

Mantle organs (Fig. 31). Pallial cavity ~3/4 whorl. Mantle border (mb) thick, white with irregular band of brown; anterior end papillated, occupying ~1/3 of mantle border. Gill located on left side of pallial cavity, occupying almost its entire length, projecting anteriorly and sustained by gill rod (sg) and suspensory membrane. Anterior end of gill narrow, with pointed tip, gradually increasing towards narrow posterior end. Osphradium rounded located at base of gill road. Afferent gill vessel ~2/3 of gill’s length, arising from transverse pallial vessel, running in distal region of central axis of gill. Transverse pallial vessel arising off from left nephrostome, discharging in afferent gill vessel. Ctenidial vein (cv) (= efferent gill) vessel about 1/3 longer than afferent vessel, running in basal region of gill central axis; its posterior 1/9 free from gill filaments, lying parallel, at left from afferent vessel up to pericardium. Hypobranchial gland (hg) on both sides of rectum; more developed on left side. Rectum ~¼ of pallial cavity width, sigmoid on posterior region under kidneys, gradually straightening towards the anus. Anus siphoned, smaller than rectum’s width; pleated, short free end, located on anterior right side of pallial cavity. Kidneys posteriorly located in pallial cavity, ~1/3 of rectum’s length.

Visceral mass. Not studied.

Circulatory and excretory systems (Fig. 31). Pericardium (pc) located between pallial cavity and visceral mass, immediately posterior to kidneys, close to median line; its left side receiving ctenidial vein and right side receiving right pallial vein.

Papillary sac (ps) of left kidney ~1/3 of rectum’s length; oval, with wide base; gradually narrowing towards anterior, ending at left of nephrostome; inner wall with numerous thin and long papillae projecting inward from all surfaces. Right kidney (rk) divided in two regions: anterior region hollow, a tube ~1/3 of rectum’s length and ~1/2 width of papillary sac in male; in female called ampulla (ap), large, oval, hollow, filled by mucus, ~3/4 larger than papillary sac; kidney expanding ventrally, covering right half of surface of adjacent visceral hump; posterior region spreading around visceral mass immediately beneath mantle, encircling inner surface of columellar muscle.

Digestive system (Figs 17–28; 32–38). Oral tube ~1/2 of odontophore in length and width; walls with circular muscles. Jaws triangular in shape, dark brown; very long denticles on anterior end, projecting in tufts (Figs 17–19). Pair of dorsal folds starting posteriorly to jaws (Fig. 33: dc), each dorsal fold bending, partially overlapping, forming two slits; upper slit rounded, ventral slit triangular. Series of transverse muscles separating outer surface of esophagus from odontophore. Odontophore about twice longer than snout. Odontophore muscles (Figs 34–38): m1, series of small muscles connecting buccal mass with adjacent inner surface of snout and haemocoel; m1d, pair of small dorsal retractors muscles, originating in postero-lateral region of mouth sphincter (Figs 35–36: mc), inserting itself in antero-lateral edge of posterior cartilage; m1v, pair of small ventral protractors muscles of odontophore, originating on surface central of oral tube, running posteriorly away from each other, inserting in postero-ventral region of odontophore, in median surface of posterior cartilages; m2a, anterior retractor muscles of odontophore, originating in antero-lateral surface of anterior cartilages and inserting in hemocelic lateral walls; m2b, posterior retractor muscles of odontophore, originating in lateral surface of anterior cartilages, posterior to m2a, inserting in haemocelic lateral walls; m4, broad pair of dorsal tensor muscles of radula, subradular membrane, originating partly in anterior cartilages, along their ventral surfaces at some distance from median line, and partly in posterior cartilages, in their posterior, lateral surfaces, surrounding anterior cartilages lateral, ventral surfaces, and inserting along subradular membrane, in its dorsal region exposed inside buccal cavity, with portion in radular ribbon in its region preceding buccal cavity; m5, pair of large accessory dorsal tensor muscles of radula, originating in ventral surface of posterior cartilages, running towards median dorsal region, subsequently running anteriorly, inserting in in posterior region of radular ribbon; m6, horizontal muscle, uniting both anterior cartilages almost along entire ventral edge, except for short posterior region, in their external surface; m7a, very long, thick pair of muscles, originating in hemocelic ventral surface, running dorsally, inserting in radular sac, posteriorly to insertion of m5; m7b, pair of muscles originating in lateral inside wall of radular sac, dividing into three thin beam muscles, two of them inserting in posterior cartilage and other entering through m10l; m8, pair of broad approximator muscles of cartilages, originating in anterior cartilages, along its lateral surface, posterior to insertion of jm, running posterior, decreasing gradually, inserting in middle region of anterior surface of posterior cartilages; m10, pair of broad ventral protractor muscles of odontophore, originating from ventral region of mouth and buccal sphincter, running posteriorly, inserting in anterior region of posterior cartilage just ventral to m8 insertion; m10l, pair of broad lateral protractor muscles of odontophore, originating from lateral oral cavity, inserting in outside of anterior region of posterior cartilage; m11, two pairs of ventral tensor muscles of radula, originating in middle region of ventral surface of posterior cartilage, one separated from other by distance equivalent to their width, running anteriorly covering m6, anterior cartilage’s ventral surface, becoming wider in anterior region, inserting in subradular membrane distal edge; m11a, very long, thin pair of oblique tensor muscles of radula, originating in hemocelic anterior surface near pleural ganglia, running dorsally through between anterior edge of anterior cartilages, inserting in subradular membrane distal edge; jm, jaw muscles, originating gradually from dorsal surface of oral tube, close to median line, running divergently towards posterior and sides, inserting themselves in latero-ventral surface of the anterior cartilage; jma, dorsal jaw pair muscles, originating in antero-dorsal region of anterior cartilage, running dorsally for short distance, surrounding oral cavity; ml, two pairs of wide and thick lateral muscles, originating in hemocelic lateral wall, running straightly forward, internal through the side wall of buccal cavity, inserting themselves in median line of lateral surface of anterior cartilage.

Radula (Figs 20–28): symmetrical, arched. Radichian (Figs 21, 25: rc) ~1/10 of total radula width, with very large base slightly rounded in shape; slender shaft; cutting edge turned posteriorly, tip narrowly tapered; finely serrated with delicate, thin, pointed and slightly elongated cusps on both sides; apical portion short, with rounded tip. Lateral teeth (Figs 21, 22, 27, 28): four pairs, ~1/3 of total radular width; shaped similarly to radichian, but with narrower base; shaft finely denticulate with long, slender cusps, becoming very slender on outer laterals; two pairs of lateromarginal plates (Figs 24, 28: pl) between innermost marginal teeth and outermost lateral teeth. Marginal teeth (Figs 23, 24, 26): about 30 teeth, occupying more than ½ of total radula width; more than twice as tall and thinner (~½) than lateral and radichian teeth; innermost pair greatly enlarged (Fig. 24), with broad base and coarsely serrated and hooked cusps; cusps curved, inner ones twice as large as outer ones; succeeding inner marginals of uniform shape; outer marginals becoming slender towards outermost region; food groove on anterior edge of shaft, below the posterior secondary cusps.

Salivary gland indistinguishable from dorsal region of buccal cavity; salivary aperture in mid-dorsal region of buccal cavity, on dorsal folds. Four dorsal fold channels; two of them are a continuation of dorsal folds in mid esophagus (Fig. 33: df); ventral food channel continuing ventral esophageal fold; esophageal valve (Fig. 33: ev) located on ventral food channel; mid esophagus with two esophageal folds, a higher ventral fold and right dorsal fold. Posterior esophagus narrow; inner surface with some longitudinal, narrow folds. Esophagus insertion and stomach not observed. Rectum, anus described above (pallial organs).

Genital system: not observed due to damage during extraction of soft parts.

Central nervous system (Figs 34–35): Nerve ring surrounding anterior half of buccal mass. Cerebral ganglia (Fig. 35: ce) rounded, located on lateral region of buccal mass and occupying ~1/3 of it; commissure thick, long; both dorsoventrally flattened cerebropleural and cerebropedal connectives (Fig. 35: cp, ccn) long and thin, originating in anterior region of cerebral ganglia, running ventrally and back to pedal and pleural ganglia. Cerebropleural connective twice as thick as cerebropedal. Labial ganglia (Fig. 35: lg) very small, ~1/5 of cerebral ganglia, located in ventro-lateral region of buccal mass, anteriorly to cerebral ganglia; linked to cerebral ganglia by short cerebrolabial connective. Buccal ganglia about same size as labia ganglia; located posteriorly to cerebral ganglia; connected united to cerebral ganglia by buccolabial connective; buccal commissure (Fig. 34: bc) thick, lying dorsally to radular sac.

Distribution.

From southern Rio de Janeiro to northern São Paulo, 23° to 24°S, 44° to 45°W, only on coastal islands (from Alcatrazes Archipelago to Jorge Grego Island).

Habitat.

On rocks and sessile invertebrates, at 3–5 meters.