3.1.1 Subfamily Buccinanopsinae Galindo, Puillandre, Louzet & Bouchet, 2016

Additional diagnosis: Fusiform shell from obese to relatively elongated. Sculptured mainly with undulating growth lines. Suture well-marked. Aperture simple, from 1/3 to 1/2 of shell length. Outer lip simple, non-determinate growth. Siphonal canal simple, wide, non-protruded. Callus normally thin. Head-foot usually unpigmented, lacking eyes; head flap-like, with tentacles on both sides. Siphon long, bearing small fold in its base. Lateral, dorso-ventral muscles uniting anterior regions of esophagus and odontophore. Pair of odontophore retractor muscles (m2) with multiple origins. Rachidian flattened, arched, ~20 cusps in cutting-edge. Stomach with posterior bulge. Penis duct thick-walled, convolute, muscular. Nerve ring with cerebral commissure long, widely arched.

Included taxa: Genera: Buccinanops (type), Buccinastrum gen. nov.

3.1.2 Genus Buccinanops d'Orbigny, 1841

Type species: Buccinum cochlidium Chemnitz, 1795 (=B. cochlidium Dillwyn, 1817) by original designation (d’Orbigny, 1841: 432). Chemnitz's work was rejected by the ICZN Direction 1 (1954). Cernohorsky (1984: 23) mentioned Herrmannsen (1846) as the source of designation. However, while on page 127 of Herrmannsen (1846) it is clearly stated that cochlidium is the type species, it is evident that Herrmannsen was only following d’Orbigny's original designation and not designating the type species himself. Allmon (1990: 20) wrongly stated that the type species was Buccinum globulosum Kiener, 1834. No reference to this type designation can be found in d’Orbigny (1841). Buccianops Adams & Adams, 1858: 113 is a typing error pro Buccinanops. The gender is masculine according to the art. 30.1.4.3 of the ICZN (1999).

Diagnosis: Shell bucciniform, medium or large, smooth, slightly shining; walls thin. Sometimes with shallow subsutural flat cords and/or small sharp nodes or spines along keel in last two or three whorls. Flat cords also covering basal surface of last whorl. First teleoconch whorls with axial riblets. Spire variable, always less than 1/3 of maximum shell height. Weak terminal columellar fold always present. Parietal callus variable, ranging from thin glazed area to thicker protuberant callus. Operculum large with smooth margins and terminal nucleus. Duplicity of pair of extrinsic odontophore muscles m1b; aperture of salivary glands ventral, close to median line; simplified anterior esophagus; papilla-like female genital pore. Radular central tooth multicuspidate, with 5–12 cusps increasing in size towards middle of tooth, rachidian base strongly curved; lateral teeth with inner and outer cusps hook-shaped, always with 1 to 3 intermediate cusps. Egg capsules always attached on the callus area of female shells only. Nurse eggs, non-planktonic larvae and crawling veliger.

Species included: B. cochlidium, B. latus sp. nov., and B. monilifer.

3.1.3 Buccinanops cochlidium (Dillwyn, 1817)

(Figures 1-8)

Buccinum cochlidium Chemnitz, 1795: 275, pl. 209, figs. 2053, 2054 (invalid name); Dillwyn, 1817: 627. Kiener, 1834: 10, pl. 6, fig. 17; Anton, 1838: 91; Deshayes, 1844: 187.

Buccinum Lamarkii (sic) Kiener, 1834: 5, pl. 3, fig. 6.

Buccinanops cochlidium: d'Orbigny, [1839] pl. 61, fig. 25; M. E. Gray, 1850: 20, 139, pl. 98, fig. 9; Carcelles & Parodiz, 1939: 751, figs. 2, 6; Carcelles, 1944: 250.

Bullia Cochlidium: Gray, 1839: 126.

Buccinum (Buccinanops) cochlidium: d'Orbigny, [1841]: 434.

Buccinum gradatum Deshayes, 1844: 186.

Bullia gradata: Reeve, 1846: pl. 1, fig. 3; Chenú, 1859: 160; Peile, 1937: 185, fig. 21; Abbott & Dance, 1986: 177, fig. 9.

Bullia cochlidium: Reeve, 1847: pl. 4, fig. 23; Hanley, 1856: 117, pl. 23, fig. 95; Chenú, 1859: 159, fig. 747.

Bullia (Buccianops) (sic) cochlidium: H. & A. Adams, 1858: 113.

Bullia (Buccinanops) cochlidium: H. & A. Adams, 1858: 113; Tryon, 1882: 13, pl. 5, fig. 73, pl. 6, figs. 76, 78.

Buccinanops (Buccinanops) cochlidium: Fischer, 1884: 636.

Bullia (Buccinanops) gradatum: Watson, 1886: 190.

Bullia (Buccinanops) cochlidium: Paetel, 1888: 116.

Bullia cochlidium: Cossmann, 1901: 220.

Bullia gradata pampeana Ihering, 1907: 445; Feruglio, 1933: 236, 239.

Buccinanops (Buccinanops) cochlidium: Thiele, 1929: 32.

Buccinanops gradatum: Carcelles & Parodiz, 1939: 754, pl. 3–5, fig. 3; Barattini & Ureta, 1960: 114; Castellanos, 1970: 92, pl. 7, fig. 6; Rios, 1970: 93, pl. 27, 1985: 103, pl. 35, fig. 453; Penchaszadeh, 1971a, 1971b: 480, figs. 1e, 2f, 2g, 1973: 15, fig. 1; Scarabino, 1977: 188, pl. 5, fig. 4; Cernohorsky, 1984: 28; Farinatti, 1985: 219; Calvo, 1987: 143, fig. 110.

Buccinanops cochlidium: Barattini & Ureta, 1960: 113, 114; Castellanos, 1970: 93, pl. 7, fig. 10; Cernohorsky, 1984: 27, figs. 94–95; Aguirre, 1993: 33, pl. 2, figs. 2 a-b; Pastorino, 1993a: 162, fig. 4–6; 1993b: 153, figs. 2–5.

Buccinanops lamarckii: Richards & Craig, 1963: 140; Rios, 1970: 93; Rios, 1975: 96, pl. 27, fig. 401; Scarabino, 1977: 189, pl. 5, fig. 3; Rios, 1985: 103, pl. 35, fig. 454; Calvo, 1987: 143, fig. 111.

Bullia (Buccinanops) cochlidia: Allmon, 1990: 20, pl. 3, figs. 1, 13, pl. 6, fig. 34.

Type material: Buccinum cochlidium: holotype ZMUC, figured by Aguirre (1993a, pl. 2, Figure 2a–b), here in Figure 1a–c; B. gradatum: holotype MHNG 1296/18 (Figure 1d–f); B. lamarckii: holotype MHNG 1296/4 (Figure 1i–k); Bullia gradata pampeana: holotype MACN-Pal 855 (Figure 1g–h).

Type localities: Buccinum cochlidium: Islands of South seas (in error); B. gradatum: New Zealand (in error); B. lamarckii: unknown, no locality mentioned; Bullia gradata pampeana: “dépôts pampiens de Puerto Militar” (Quaternary deposits at Puerto Belgrano, Buenos Aires province).

3.1.4 Description

Shell: (Figures 1, 2) Large (maximum height 95 mm), somewhat variable, usually fusiform. Protoconch paucispiral of 1.5 to 2 whorls, 1.5–1.7 mm wide in second whorl; first whorl smooth, followed by 10–12 weak axial riblets after second whorl (Figure 3a–b). Teleoconch of 6–7 shouldered or globose whorls. Spire rounded, ~1/3 of total shell length. Suture well defined, impressed; blunt subsutural carina in ~50% of specimens; aperture large, usually half of total shell length. Parietal callus usually weak, stronger in large specimens. Sculpture absent except for growth lines and shallow undulations. Left edge of siphonal canal with pointed anterior beak of ~30°. Ultrastructure of shell usually with three layers, outermost layer very thin or absent, of amorphous calcite, intermediate layer thicker, of crossed-lamellar aragonite, with crystal faces oriented collabrally, and innermost layer thinner, of crossed-lamellar aragonite oriented perpendicular to outer lip.

Head-foot: (Figures 3a–c, 4a–c) Head weakly protruded, somewhat socket-like, narrow (~50% of head-foot width); color dark-brown, almost black (Figure 3c) in exposed areas (except for foot sole and opercular pad), particularly darker in head and in median-dorsal area of foot. Tentacles well-separated from each other; elongated and narrow, eyes absent (Figure 4a–c). Rhynchostome as longitudinal slit located in middle region of lightly protruded head ventral surface (Figure 4a–c: ry). Foot broad, of about 3/4 whorl when retracted. Sole rather triangular, edges thick and rounded (Figure 4a–b: fs). Anterior furrow of pedal glands almost imperceptible, marked by narrow furrow in anterior edge (Figures 3a: pg, 4b); pedal gland thick in medial region, immersed in pedal musculature (Figure 3a: superior pg). Single, small epipodial tentacle (ed) located in dorso-posterior end of foot, originating in dorsal region of edge posterior to operculum. Opercular pad elliptical, ~50% as wide as dorsal surface of foot; attachment with operculum occupying ~80% of its area (Figures 3c, 4b: oa). Columellar muscle thick, spanning, ~1.5 whorl; distal end bifid, right element wide (cm), left element narrow (cs), encased in furrow kept by columellar fold (Figure 4a-b). Female with small orifice of cement gland located on median line of anterior sole region (Figure 3a: cl); inner space wider than narrow duct.

Operculum: (Figures 2m-n, 4a: op) Elliptical, corneous, pale brown, translucent. Nucleus terminal in inferior corner. Outer edge straighter than inner edge. Outer surface with concentric growth lines, forming undulations. Scar oval, occupying about 80% of inner area, somewhat dislocated closer to inner edge.

Pallial cavity: (Figure 5a, d) Mantle edge simple, thick. Siphon long, slender, ~10% of mantle edge length, almost as long as 2/3 of pallial cavity when retracted (Figure 5a: si); edges simple. Osphradium of ~1/2 length, and 1/10 width of pallial cavity; anterior end pointed, but more rounded than narrow, tail-like posterior third (Figure 5a: os); osphradium filaments symmetrical, relatively low, isosceles-triangular (Figure 5d: os). Very narrow area between osphradium and gill. Ctenidial vein (cv) narrow, with uniform width along its length. Gill (gi) ~80% of pallial cavity length, ~1/2 its width at widest middle region; anterior end broadly pointed, located at some distance from mantle edge. Posterior gill end slightly more pointed than anterior end, touching pericardial area. Afferent gill vessel very narrow, lying at short distance from right edge of gill (Figure 5d: af). Gill separated from right edge of pallial cavity by area equivalent to its width. Hypobranchial gland thin, light-brown, covering most of area between gill and rectum, slightly thicker in anterior quarter, vaguely pigmented light-brown. Rectum broad, with thick walls, running along right edge of pallial cavity (Figure 5d: rt). Anus simple, siphoned (terminally detached), located near mid length of pallial cavity (Figures 5d, 7c: an). Pallial gonoducts located between rectum and pallial right edge as described below.

Visceral mass: (Figure 5a) Anterior quarter of whorl mostly occupied by kidney (km) and pericardium (pc). Digestive gland light-brown, located along inferior (siphonal) region of each visceral whorl, covering middle digestive tubes and two whorls posterior to stomach. Gonad pale light-brown, lying along superior and columellar surfaces of visceral whorls posterior to stomach. Stomach small, located half whorl posterior to pallial cavity (Figure 5a: st).

Circulatory and excretory systems: (Figure 5a) Pericardium located just posterior to gill, along left anterior region of visceral mass (pc), slightly dislocated anteriorly along right side of posterior 1/10 of gill. Auricle (au) small, attached to anterior surface of pericardium, with ctenidial vein entering from left and connected to kidney at its right end. Auricle connected to anterior surface of ventricle. Ventricle (ve) large, rounded. Aortas located along postero-left region of ventricle. Kidney volume equivalent to ~1/4 of pallial cavity volume, 4-times larger than pericardium; located along middle and right regions of anterior end of visceral mass. Nephridial gland (ng) triangular in section; lying along dorsal-right region of reno-pericardial wall. Renal lobe (kl) in three longitudinal, thick flaps, turned to left, transversely folded, occupying most of kidney's interior volume (Figure 5a: kl); intestine running along kidney right side. Efferent renal vessel (ek), well-developed, inserted in dorsal kidney lobe flap.

Digestive system: (Figures 4c, 5b, c, e–f, 6) Proboscis as long as foot, 1/4 of head-foot width (Figure 4c: pb). Circular mouth at proboscis tip (Figure 5b: mo). Buccal cavity with pair of broad and low dorsal folds (Figure 6a: df), occupying ~1/3 of dorsal wall, with interval between them slightly broader than each fold. Odontophore oval, as long as retracted proboscis (Figure 5b: od). Odontophore tube connecting it with buccal cavity, length equivalent to ~1/5 of odontophore length, possessing mostly longitudinal muscles (Figure 6a, c: ot). Odontophore muscles (Figure 6a–f): m1, several small jugal muscles connecting buccal mass to adjacent inner surface of proboscis; one pair more developed originating in peribuccal lateral region of proboscis, running posteriorly, inserting in lateral side between middle and posterior thirds of odontophore (Figure 6b–c: m1l); tm, pair of transverse muscles connecting lateral walls of odontophore with adjacent wall of esophagus (Figures 5b, 6a: tm), along anterior third of odontophore; set of m2, several retractor muscles of odontophore, part of them working also as dorsal tensor muscles of radula, all originating in ventral surface of hemocoel, in region just posterior to proboscis, running anteriorly, some median fibers running through nerve ring, insertions as following: m2m, median m2, single, inserting on radular nucleus together with small branch of aorta (Figure 6b–e); m2a, broad and thick pair auxiliary of m2 and dorsal tensor muscles of radula, with 4–5 separated pairs of bundles, inserting along radular sac in its middle-lateral regions (Figure 6b–e); m2c, lateral odontophore retractors, inserting at posterior end of each odontophore cartilage (Figure 6b–e); m3c, single circular, constrictor muscle covering? dorsal surface of odontophore, inserting along outer side of dorsal edge of cartilages at along ~70% their length (Figure 6b–f); m3l, pair of narrow, lateral longitudinal muscles, originating in lateral region of odontophore tube, running posteriorly attached to odontophore lateral surface, inserting in fan-like manner lateral side of m3c posterior surface (Figure 6b); m4, strong pair of dorsal tensor radular muscles, originating in odontophore cartilages on posterior-ventral surface, running toward dorsal surrounding lateral surface of cartilages, inserting laterally along radular sac (Figure 6b–f); m4a, 4–5 small pairs auxiliary of m4, of similar attributes, but originating in bundles along outer-dorsal edge of cartilages, in their posterior quarter (Figure 6c–f); m5, pair of secondary dorsal tensor muscles of radula, originating in posterior-dorsal surface of posterior end of cartilages, running dorsally and medially mixing with m4, inserting into radular sac alongside and medial to m4 insertion (Figure 6e–f); m6, thin horizontal muscle, uniting both odontophore cartilages just posterior to anterior fusion, along ~70% of cartilage length, inserting along ventral and internal edge of cartilages, becoming gradually wider posteriorly (Figure 6e–f); m8, pair of cartilages shortener muscles, located along dorsal edge of anterior region of cartilages, along almost 1/3 their length, thicker anteriorly, gradually narrowing posteriorly (Figure 6d–f); m9, two pairs of narrow protractor muscles of radula, one located just anterior from another (posterior slightly broader), originating on posterior half of dorsal edge of cartilages, running medially towards anterior, inserting along m3c anterior fibers (Figure 6c–d); m11, pair of ventral tensor muscles of radula, thin, narrow, originating in posterior-ventral end of cartilages, running anteriorly, and medially covering m6, inserting into ventral edge of radula and subradular cartilage, and some inner portion preceding this (Figure 6e). Subradular cartilage expanding in exposed region of radula into buccal cavity, covering neighboring surface of radula (Figure 6c: sc); oc, odontophore cartilages, elongate, furrow-like, flattened, ~20 times longer than wide; fusion between both cartilages in anterior-medial end, along ~20% their length (Figure 6e–f); subradular membrane, covering inner surface of subradular cartilage and radula, having insertions of m4, m5 and m11 (Figure 6d–e). Radula (Figure 3e–f): slightly longer than odontophore, ~50 rows of teeth; rachidian tooth wide, comb-like, occupying ~half of radular width; base curved, width ~3 times greater than its length; ~9 long, sharp pointed cusps of similar size, except for some diminishment toward lateral edges, lateral cusps very small, sometimes vestigial; distance between rachidian and lateral tooth equivalent to 1/3 of rachidian width; lateral tooth with two major and 2–4 minor long cusps; base equal in width to rachidian tooth; base deflected posteriorly by ~50 degrees; outer cusp about as long as tooth base, scythe-shaped; inner cusp shorter, stout, with 2–4 shorter cusps of decreasing size emerging from its surface outer cusp and set of inner cusps separated from each other by smooth area equivalent to 1/4 tooth's width. Salivary glands enveloping esophagus along region of valve of Leiblein and nerve ring (Figures 4c, 5b: sg), size slightly larger than nerve ring; their ducts very narrow, running along anterior esophagus wall and, more anteriorly, inside dorsal folds of buccal cavity (Figure 6a: sd); opening with very small pore (Figure 6a: sa), into anterior-middle region of dorsal folds of buccal cavity; salivary ducts with enlarged bulges along middle area of dorsal folds (Figure 6a: ss). Anterior esophagus with somewhat thick walls, twice length of odontophore; inner surface with 12–15 narrow, uniform longitudinal folds; posterior half zigzagging intensely (Figures 4c, 5b: ae). Valve of Leiblein almost imperceptible externally; inner structure only marked by transverse wide glandular fold (Figure 5f: vl), lacking any valve or long cilia; smooth area anterior and posterior to transverse fold (Figure 5f); oblique furrow (bypass) absent. Middle esophagus ~5% of anterior esophagus length (Figure 5e: me), walls thin; inner surface like that of anterior esophagus; aperture of gland of Leiblein as a minute pore. Gland of Leiblein narrow, elongated (Figures 4c, 5b: gl), ~70% posterior esophagus length; anterior region ~double of middle esophagus width, gradually tapering toward posterior; middle portion surrounding local portion of anterior aorta (Figures 4c, 5b: aa). Duct of gland of Leiblein short, narrow, simple (Figure 5b, e: gd). Posterior esophagus (Figures 4c, 5b: ep) ~70% anterior esophagus length, very wide (4–5 times wider than wider portion of anterior esophagus), slightly flattened, narrowing gradually posteriorly (Figure 5a: ep) in same width as anterior esophagus; inner surface with 12–15 narrow, tall, irregular, sometimes coalescent longitudinal folds. Stomach small blind sac, ~1/4 width of adjacent visceral whorl, ~1/4 whorl long; located ~half whorl posterior to pallial cavity, approximately in middle position of that whorl (Figure 5a: st). Esophageal insertion and intestinal origin in anterior side of stomach relatively well-separated from each other; 2 narrow ducts to digestive gland, being one in esophageal insertion, turned posteriorly, another in intestinal origin, turned left (Figure 5a: dd). Gastric inner surface mostly smooth. Intestine about as wide as adjacent posterior esophagus; weakly sigmoid visceral loop (Figure 5a: in) immersed initially in digestive gland, afterwards passing though ventro-left side of kidney, immersed in renal lobe. Rectum and anus described above (pallial cavity).

Genital system: Male: (Figures 4a, 7a, b, e) Gonad along columellar region of each visceral whorl. Intensely coiled seminal vesicle (Figure 7a: sv) along ~1/2 whorl in region preceding pallial cavity; placed slightly obliquely; more posterior region narrower, gradually widening anteriorly; narrowing in region preceding pallial cavity in short zigzag in central-left region of visceral anterior border, just posterior to nephrostome (Figure 7a: ne). gonopericardial duct relatively wide, inserting in vas deferens at end of its coiled portion (Figure 7a: go). Prostate spanning about 1/3 pallial cavity length, narrow, closed (tubular), lying ventrally and to right of rectum (Figure 7a: pt). In region posterior to anus, vas deferens gradually crossing to pallial cavity floor, narrow; walls relatively thick, running relatively straight up to penis base (Figure 7b: vd) immersed in pallial floor integument. Penis slender, curved backwards in base, about ~80% of pallial cavity length, ~15 times longer than its width, dorso-ventrally flattened (Figures 4a, 7b: pe); base narrow, located at some distance from right tentacle (Figure 4a); middle level twisting, narrowing gradually up to blunt tip, with small right papilla (Figures 3d, 7b, e: pp). Penial duct running approximately along penis center, narrow, intensely coiled along its entire length, slightly less coiled and narrow in distal 1/5 (Figure 7b: pd). Penial aperture in apex of papilla (Figure 7e: pd), very small.

Female: (Figure 7c–d) Visceral oviduct narrow, running along middle region of columellar surface of last whorl of visceral mass, closely preceding pallial cavity (Figure 7c: vo). Posterior region of pallial oviduct protruding into kidney. Albumen, whitish, (Figure 7c: ag) and capsule, pale beige, (cg) glands adjacent, albumen gland spanning posterior 1/5 of pallial oviduct. Seminal receptacle absent. Capsule gland with flat lumen, vaginal furrow running along its left edge, with surface smooth (Figure 7d: cg). Vaginal duct as tapering region preceding female pore (Figure 7c–d: vg), wall thin, inner surface narrow longitudinal folds. Female pore narrow, weakly protruded, papilla-like, sheltered in shallow cavity (Figure 7c: fp). Bursa copulatrix absent. Cement gland in pedal sole described above (head-foot) (Figure 3a: cl).

Central nervous system: (Figure 8a–b) Well-concentrated, most connectives and commissures indistinct; total nerve ring volume ~1/30 that of hemocoel. No distinction between pleural and cerebral ganglia (ce). Each cerebral/pleural ganglia ~1/4 of nerve ring volume. Cerebral commissure very long, strap-like, extending dorsally ~30% more than nerve ring size; narrow in middle, thickening on both sides, without clear distinction with cerebral ganglia (Figure 8a–b: cc). Pedal ganglia (pl) slightly smaller than cerebro-pleural ganglia; located just ventral to cerebro-pleural ganglia as almost single mass; deep furrow separating both pedal ganglia (Figure 8b: pl). Buccal ganglia (Figure 8a: bg) small, located side by side in region close to left cerebral ganglion. Visceral ganglion (Figure 8a: vg) ~1/4 of pedal ganglion size, located 3-times nerve ring length posteriorly to it. Subesophageal ganglion not detected, possibly embedded within nerve ring.

Habitat: Inhabits sandy bottoms, from 6 to ~50 m depth. It feeds primarily on dead fishes and crustaceans. It is frequently found associated with the sea anemone Antholoba achates (Drayton in Dana, 1846) (as Phlyctenanthus australis in Pastorino, 1993) in the Peninsula Valdes area (~42°S), living on the dorsum of the shell. Occasionally it has been observed feeding on live bivalves.

Distribution: From Rio Grande do Sul, Brazil (~32°S) to Puerto Madryn, Golfo Nuevo, Chubut, Argentina (~42°S).

Material examined: BRAZIL. Rio Grande do Sul. Rio Grande, Tramandaí, MZSP 77556, 1 spm, MNRJ 6092, 2 spm; Praia do Imbe, MNRJ 2923, 2 spm, MNRJ 6062, 2 spm; Cassino, MZSP 61463, 7 spm, MZSP 19197, 3 spm, MZSP 44023, 2 spm, MACN-In 8221, 2 spm, MNRJ 690, 2 spm, MNRJ 3467, 3 spm, MNRJ 4172, 1 spm; Albardão, MZSP 16203, 2 spm; MZSP 51731, 1 spm in 13 m, 32°58'S, 52°30'W; MZSP36633, 1 spm; MZSP 53201, 3 spm; 531, 6 spm; MZSP 19178, 3 spm; MZSP 19179, 5 spm; MZSP 19180, 3 spm; MZSP 19181, 1 spm; MZSP 19182, 3 spm; MZSP 19184, 1 spm; MZSP 19186, ~10 spm; 29°43′S 49°55′W, 24 m, MZSP 19187, 1 spm (GEDIP sta. 1715, RV W. Besnard col, 8.iv.1972); MZSP 19188, 5 spm; MZSP 19189, 1 spm, Albardão-Sarita, 18–28 m, MNRJ 2872, 3 spm; Pta. Cidreira, MNRJ 2922, 3 spm; São Jose do Norte, Praia Grande, MNRJ 691, 2 spm; Ponta da Cidreira, MNRJ 2177, 2 spm; No precise locality, MZSP 19190, 1 spm; MZSP 19192, 2 spm; MZSP 19197, 1 spm; MZSP 32892, 3 spm; MZSP 32902, 3 spm; MZSP 51313; 33°24′S, 52°47′W, MACN-In 15347, in 13 m, 3 spm. URUGUAY. Rocha; MZSP 51679, 2 spm, MZSP 52424, 1 spm; Cabo Santa Maria, MZSP 13394, 1 spm; MACN-In 23569, 6 spm; USNM 331316, 1 spm; La Coronilla, USNM 359259, 1 spm; La Paloma, MZSP 19183, 2 spm, MZSP 19196, 3 spm; MZSP 33348, 1 spm; MZSP 33400, 2 spm, MNRJ 1236, 3 spm, MNRJ 6546, 2 spm, MACN-In 15151, 14 spm; MACN-In 30484, 3 m, 3 spm, MACN-In 15314, 6 spm. Maldonado; MZSP 10050, 10 spm, MZSP 51654, 2 spm; Punta del Este, MZSP33353, 1 spm; Piriapolis, MACN-In 18158, ~30 spm, MZSP 57510, 34°5′S 53°30′W, in 20 m, MACN-In 15922, 34°38′S, 52°15′W, 128 m, 1 spm. ARGENTINA. Buenos Aires; MACN-In 15851, 35°24′S, 53°10′W, 28 m, 1 spm, MACN-In 25200, 35°40′S 56°03′W, 9 m, 22 spm, MACN-In 15980, 35°08′S 52°35′W, 6 spm, MACN-In 24147 36°24′S 55°53′W; MACN-In 24300, 36°44′S 56°34′W, 9 m, 9 spm; off Ostende, MACN-In 21779, 1 spm; Mar Chiquita, MACN-In 3922, 1 spm; Mar del Plata, MACN-In 10287, 2 spm, MACN-In 19140, 3 spm, MACN-In 19273, 8 spm, MACN-In 10768, 5 spm, MACN-In 12069, 1 spm, MACN-In 11999, 3 spm, MACN-In 9363-12, MACN-In 19139-1, 1 spm; Villa Gesell, MACN-In 28827, 2 spm; 38°08′S 56°58′W, MACN-In 23380, 60 m, 4 spm; Puerto Quequén, MACN-In 23206, 26 spm, MACN-In 18672, 5 spm; Necochea, MACN-In 9368-28, 2 spm; Ostende, MACN-In 20099, 7 spm; Monte Hermoso, MACN-In 6619–31, 8 spm, MACN-In 11230, 18 spm, MACN-In 9209-17, 3 spm, MZSP 51650, 10 spm, MZSP 389, 7 spm, 10056, 1 spm; USNM 219862, 6 spm; USNM 465581, 1 spm; Cabo San Antonio, MACN-In 16306, ~36 spm; Carmen de Patagones, MZSP10058, 10 spm; Arroyo Parejas, Bahía Blanca, MACN-In 11232, 12 spm; Puerto Belgrano, MACN-In 11123–1, many spm; Bahía San Blas MACN-In 22943, 3 spm, MACN-In 20273–1, 2 spm; Mouth of Rio Negro river, MACN-In 20526, 1 spm; 40°56′S 62°28′W, 17 m, MACN-In 20671, 2 spm. Rio Negro; Puerto San Antonio, USNM 568254, 2 spm; San Antonio, MZSP52101, 1 spm; Faro Punta Villarino, San Antonio Oeste, MACN-In 13146-2, 2 spm, MACN-In 9376; MACN-In 9379–30, 4 spm, MACN-In 9152, MACN-In 9152-14, 18 spm, MACN-In 9379–31, ~26 spm, MACN-In 23705, 1 spm. Chubut; Golfo San Matias, MZSP 51328, 1 spm, MZSP 10057, 2 spm, MACN-In21203, 4 spm, MNRJ 36, 1 spm; Faro Punta Villarino, MACN-In 13146-1, 1 spm; Puerto San José, MACN-In 9174, 2 spm; Playa Larralde, MACN-In 37814, 12 spm; Puerto San José, MACN-In 26435, 128 m, 14 spm; Golfo San José, MACN-In 9174–15, 2 spm, MACN-In 9441-6, 9 spm; Playa Villarino, 42°24′S 64°17′W, MACN-In 38162, 10 m, 25 spm; Peninsula Valdes, MNRJ 2927, 2 spm, MNRJ 9399, 2 spm; Puerto Pirámides, MACN-In 26434, 14 spm. MACN-In 11484, 7 spm; Punta Norte, MACN-In 9158-7, 2 spm; Puerto Madryn, MZSP10054, 2 spm.

Remarks: Buccinum cochlidium Chemnitz, 1795 was rejected by ICZN Opinion 184 (1944) and Direction 1 (1954), which rejected and made invalid all new specific names proposed in that work. The next available name in line was also Buccinum cochlidium, changing the author to Dillwyn (1817). When Deshayes (1844) reviewed the 2nd edition of Lamarck's Histoire Naturelle des animaux sans vértebrés, he described Buccinum gradatum based on the specimen housed in Lamarck's collection and figured by Kiener (1834: 10, pl. 6, Figure 17) (Figure 1d) as Buccinum cochlidium. The material is now at MHNG (Figure 1e–f). Tryon (1882) raised some doubts about the validity of B. gradatum; however, the name was sustained by most later authors. The probable holotype of Buccinum lamarckii Kiener, 1834, housed in MNHNG (Figure 1i–k) clearly represents the southern morph of Buccinanops cochlidium.

A. d'Orbigny (1839, pl. 61, Figure 25) (reillustrated by M. E. Gray, 1850) depicts an apparently juvenile specimen of Buccinanops cochlidium. Later, Pilsbry (1897) considered it as Bullia uruguayensis. The figure is not clear and based on a juvenile specimen and could be any one of these species. The Buccinanops material from d’Orbigny's collection, housed in NHMUK was examined, and we conclude that it contains several lots with the following species: B. deforme: 1854.12.4.469, 4 sp., 1854.12.4.470, 11 sp.; 1854.4.466, 6 sp.; B. uruguayense 1854.12.4.467, 12 sp.; B. monilifer: 1854.21.4.465, 9 sp.; B. paytense: 1854.21.4.463, 1 sp.; B. cochlidium: 1854.21.4.461, 4 sp.; 460, 2 sp.; 462, 1 sp.; 464, 3 sp.; 459, 1 sp.; 458, 1 sp.

Ihering (1907) described Bullia gradata pampeana, a fossil subspecies from Quaternary deposits of Pleistocene age according to Parodiz (1996). Ihering (1907) also mentioned doubts about the differences between his Bullia gradata and B. cochlidium, showing that the typical form without subsutural cord (B. cochlidium) gradually change to that of thicker shell, with subquadrate profile and rectangular whorls (B. gradatum). Cernohorsky (1984) also mentioned the possibility that Buccinanops gradatum could be only a variation of B. cochlidium. However, several modern authors (e.g., Calvo, 1987; Rios, 1985) keep both names in use. Later, Allmon (1990) included B. gradatum in the list of synonyms of B. cochlidium. Allmon (1990) also subordinated Buccinanops as a subgenus of Bullia which was discussed by Pastorino (1993a) who reinstated the full generic status.

Buccinum turritum Perry, 1811, was mentioned by Deshayes (1844) as a dubious synonym of B. cochlidium Chemnitz. Petit (2010) stated that Perry's name could be nomen dubium until “specialist with all the available types rule out about the validity of this name.” We have seen all the existent type material related with these names, and there is none with real similarity to the picture of B. turritum. The regular axial ribs, particularly on the last whorl, appear as a characteristic feature of B. turritum, which are absolutely absent in any species of Buccinanops. We agree with Petit's designation of B. turritum as a nomen dubium and according to our observations, without any relationship with the genus Buccinanops.

Tryon (1882) and Allmon (1990) synonymized Buccinum labyrinthum Gmelin, 1791 from the Netherlands coast with Buccinanops cochlidium. Pastorino and Kantor (1998) discovered that Gmelin's species is actually an anomalous specimen of Buccinum undatum L. with no connection to the South American species.

Penchaszadeh (1971, 1973) described the egg capsules of several species of Buccinanops including material of the form "gradatum" from Mar del Plata, Buenos Aires, Argentina. The morphology and ornamentation of the capsules are exactly the same of those from specimens from Puerto Pirámide, off Chubut Province where the only available form is "cochlidium."

3.5.1 Distinctive description

Shell: medium size (to 70 mm, with usually 45 mm), globose. Protoconch (Figure 16c–e) of 2–2.5 whorls, of ~1.3 to 1.6 mm wide in second whorl (n=3), smooth or with weak sparse spiral lines (Figure 16e); whorls convex, globose. Spire short, ~40% of length; last whorl very globose, of ~60% of total length. Suture well defined. Sculpture wanting, except for growth lines (Figure 16c, h, k). Aperture large, oval, ~60% of shell length and width. Siphonal fasciole simple, rising below anterior half of callus. Columellar callus defined, weak (Figure 16a, j) or strongly pronounced (Figure 16d, g, m). Columella curved, ending in characteristic terminal plait. Outer lip barely sigmoid (Figure 16b, e, l, n).

Head-foot and operculum: Similar to those of preceding species (Figure 17a). Clearly bilobed posterior end of columellar muscle (cm), left-slender component tall (cs). Females with cement gland in middle region of anterior third, ending away from hemocoel (Figure 17d: cl). Operculum (Figure 17o, p) large, suboval, with subterminal nucleus.

Pallial cavity: (Figure 17c, e) Features similar to preceding species. Gill (gi) proportionally broader, occupying ~half of pallial roof; gill filaments relatively lower, with right edge usually convex. Osphradium slightly asymmetrical, with left filaments ~20% smaller than right filaments. Small fold separating anterior end of gill from osphradium, perpendicular to mantle border (ac).

Circulatory and excretory systems: (Figures 17b–c, 19a) Most characters alike those of preceding species. Kidney with two flaps of renal lobes (kl), both connected to efferent renal vessel (ek) and to intestine (in). Hollow inner space wider, mainly in posterior region.

Digestive system: (Figures 18, 19) Most features similar to those of preceding species. Exclusivities and notable characters are lateral transverse muscles (tm) slightly less developed (Figure 18a), odontophore cartilages slightly broader and shorter, with pair m8 longer (~45% of cartilage's length); fusion of cartilages along ~25% of their length (Figure 18d: oc); pair of muscles m9 as single, broad bulk in each side (Figure 18b: m9); pair m4 with broader origins (Figure 18d: m4); posterior end of m6 and m3c closer to posterior end of cartilages (Figure 18d), at ~1/7 of cartilages length from their posterior end. Radula: rachidian tooth with 6–12 cusps increasing towards center; rachidian base strongly curved; lateral teeth with outer cusp hook-shaped, inner cusp larger than 2–3 intermediate cusps. Lateral teeth base with blunt inner cusp. Salivary gland ducts lacking subterminal bulged region (Figure 18c: sd); salivary aperture close to median line on ventral wall, at middle level of oral tube (Figure 18c: sa); inner surface with 5–6 longitudinal, low folds, separated from each other (Figure 18e: ae). Anterior esophagus simpler, almost straight (Figure 18a: ae). Valve of Leiblein well-developed (Figure 18a, e: vl), with an inner transverse glandular fold and long iridescent cilia turned proximally; no bypass furrow. Middle and posterior esophagus internally smooth (Figure 18e: me, ep); middle esophagus very short; posterior esophagus gradually acquiring 5–6 inner, longitudinal folds (Figure 19a: ep). Gland of Leiblein narrow, shorter (Figure 18a: gl), its duct short, simple, hollow; opening as simple pore (Figure 18e: gd). Pair of ducts to digestive gland (Figure 19a: dd), being esophageal duct ~half of intestinal duct. Stomach bulged backwards, with strong circular muscle (Figure 19a: st); internally with two transverse folds, one in esophageal insertion, another in intestinal origin.

Genital system: (Figure 19b–e) Most attributes similar to those of preceding species, distinctions following. Male seminal vesicle slightly less-developed (Figure 19b: sv), with gonopericardial duct present (go). Prostate simple, narrow, simply as duct swelling. Penis broad in base (Figure 17a: pe), tapering gradually and uniformly up to bluntly pointed tip (Figures 19e, 21a: pe); penis duct smoothly zigzagging along penis center (pd); papilla very small, subterminal (pp). Female pallial oviduct with shallow constriction between albumen and capsule glands (Figure 19c–d: ag, cg), albumen ~half of capsule gland length; inner lumen very flat. Vaginal atrium ~1/5 of pallial oviduct length, with posterior, dark-colored ingesting gland (ig). Female pore simple, with elevated edges (Figure 19c: fp).

Central nervous system: (Figure 19f–g) Characters similar to those of preceding species, being slightly broader. Cerebral commissure (cc) relatively short, broad, rounded. Pair of buccal ganglia (bg) located slightly separated from each other.

Habitat: Sandy and sandy-mud beaches, intertidal to shallow subtidal levels.

Distribution: Cabo Santa Maria, Uruguay to southern Santa Cruz, Argentina.

Material examined: URUGUAY. Rocha; Cabo Santa Maria, USNM 340683, 3 spm. Maldonado; USNM 334528, 2 spm, USNM 270864, 1 spm; Punta del Este, MZSP 32081, 5 spm, MZSP 43098, 1 spm; MZSP 51347, 2 spm, MZSP 51628, 6 spm, MNRJ 6163, 2 spm; Ilha Dos Lobos, MNRJ 1215, 1 spm, USNM 359242, 2 spm; Solis, MACN-In 9536–2, 2 spm; Piriapolis, MACN-In 15433, 4 spm; Punta Negra, MNRJ 1772, 2 spm, USNM 359231, 4 spm. Canelones; Montevideo, MZSP 52109, 6 spm, USNM 364197, 7 spm; Isla Flores, MACN-In 28970, 2 spm; MNRJ 856, 3 spm. ARGENTINA. MZSP 54048, 2 spm. Buenos Aires; Cabo San Antonio, MACN-In 16310, 10 spm; Mar del Plata, MACN-In 8653–7, 2 spm, MACN-In 9155–4, 3 spm; Punta Carballido, Puerto Quequén, MACN-In 26280, 1 spm; Monte Hermoso, MZSP 51592, 7 spm, MZSP52112, 2 spm, MACN-In 11235, 23 spm, USNM 219861, 1 spm, USNM 465578, 2 spm; Bahía Blanca, MZSP 10045, 3 spm, MACN-In 14868, 40 spm, MACN-In 11236, 21 spm; Puerto Belgrano MACN-In 11236–1, 2 spm, MACN-In 6620–17, 2 spm; Arroyo Parejas, MACN-In 22471, 2 spm, MACN-In 11234, 3 spm; Bahia San Blas, MACN-In 20252, 61 spm, MACN-In 20273–2, 3 spm; Isla Trinidad, MACN-In 19678, 1 spm; Carmen de Patagones, MZSP 52104, 15 spm; MZSP 10048, 4 spm, MZSP 52102, ~100 spm; mouth of the Río Negro, MACN-In 20528, 17 spm; Río Negro; Puerto San Antonio, MACN-In 9379, 3 spm, MACN-In 9379–28, 14 spm, MACN-In 9152–13, 12 spm, MACN-In 13359, 15 spm, MACN-In 9379–24, 2 spm, MACN-In 9379-26/27, 113 spm, MACN-In 9379, 25 spm, USNM 346842, 3 spm; Puerto San Antonio Este, MACN-In 23703, 12 spm, MACN-In 13358, 6 spm, MACN-In 29138, 2 spm, MZSP 52103, 3 spm, MZSP 10032, 2 spm, MZSP 78270, 3 spm, MACN-In 29662, 2 spm, USNM 381691, 3 spm; Punta Villarino, MACN-In 13145, 16 spm, MACN-In 13146–3, 5 spm; San Antonio Oeste, USNM 807981, 2 spm Chubut; Golfo San Matias, MACN-In 33041, 3 spm; Puerto San José, MACN-In 9174–13, 5 spm; Puerto Madryn, MACN-In 38163, 42°24′S 64°17′W, 3 spm, MACN-In 9676–1, 5 spm, MACN-In 9281–2, 2 spm, MACN-In 22477, 35 spm, MACN-In 10953, 41 spm, MACN-In 9171–20, 25 spm, MACN-In 9040, 12 spm, MACN-In 9171–31, 3 spm, MACN-In 9675, 32 spm, MZSP 52111, 8 spm; Golfo San José, MACN-In 9032–14, 12 spm; Punta Norte, MACN-In 11485, 51 spm, MACN-In 9158–6, 5 spm; Puerto Pirámides, MACN-In 26400, ~100 spm, MACN-In 26402, 3 spm, MACN-In 9177–4, 12 spm; Bahía Craker, MACN-In 26437, 20 spm; Bahía Bustamante, MACN-In 26436, 2 spm, MACN-In 14447, 1 spm, MACN-In 26401, 2 spm, MACN-In 9032–34, 3 spm; Camarones, MACN-In 26438, 11 spm; Rada Tilly, MACN-In 30881, 28 spm; Comodoro Rivadavia, MACN-In 6826, 12 spm; Golfo de San Jorge, MNRJ 2069, 2 spm. Santa Cruz; Caleta Olivia, MACN-In 35384, 3 spm.

Remarks: Buccinastrum deforme (King, 1832) was described in one of the first molluscan reports from southern South America. However, the type was never illustrated. Kiener (1834) described Buccinum globulosum without any reference to King (1832). Later authors (e.gBarattini & Ureta, 1960; Carcelles & Parodiz, 1939; Castellanos, 1970; Cernohorsky, 1984) used both names as distinct species. The two syntypes housed at the NHMUK (Figure 16a–f) clearly show extremes of variation of only one species (Figure 16g–h). Usually, individuals living in Buenos Aires province and Uruguay have shorter spire, heavier columellar callus, and reduced aperture. This is probably related to the selective predation of crabs of the genus Danielethus Thoma, Ng & Felder, 2012 which fracture the shell using a special denticle on the master claw. Along the coast of Chubut province and southwards, these crabs are absent. Thus, the shells develop a higher spire, thinner whorls, and larger aperture (Figure 16j–l). Gomez Espinosa et al. (2018) showed the relationship between the crab D. crenulatus and B. deforme. Narvarte (2006) studied the population ecology of the so-called B. globulosum. It is sympatric with B. cochlidium particularly around Peninsula Valdes area; however, both species live at different depths. While B. deforme is found in intertidal settings—usually never deeper than 6 m—B. cochlidium never is exposed during low tide, living in considerably deeper environments. The interaction between the American Oystercatcher (Haematopus palliatus) and B. deforme (as B. globulosum), which feeds on the leftovers of the crabs (Cyrtograpsus angulatus), was studied by Daleo et al. (2005).

In the original description of B. deforme, King (1832: 349) mentioned the presence of “eggs” attributed to it. According to his description, those capsules—“transparent nidus, the size of a turtle's egg”—actually belong to the volutid Adelomelon brasiliana (Lamarck, 1811), a species fairly common in the area.

The radula of B. deforme is uniform in interpopulational studies. There is no sexual dimorphism, neither differences between distant populations nor variation correlated with size in specimens (Avaca et al., 2010).

3.6.1 Distinctive description

Shell: (Figures 20e–i, l–n, 21e) Medium size (up to 35 mm), fusiform. Protoconch paucispiral of 2 globose, smooth whorls. Teleoconch up to 6 flat whorls. Growth lines all over shell, otherwise smooth. Most grown specimens usually with small scars—probably boring sponges (Clionaidae) (Figure 20h–i). Color pinkish, purplish, or clear brownish; irregular subsutural white line usually present. Spire less than half of total shell length. Suture impressed, sometimes irregular, overgrown, showing enameling. Aperture large, usually half of total shell length (Figure 20e, h, l). Parietal callus usually well-developed, reducing aperture. Inner lip concave, siphonal inflexure strong. Outer lip barely convex, almost straight (Figure 20f, m). Inferior inner groove internally in each whorl (Figure 21e: arrow).

Shell ultrastructure similar to other Buccinastrum spp.

Head-foot and operculum: (Figures 22a, 23a) Characters similar to preceding species. Operculum (Figure 20j–k) large, suboval, margin smooth, subterminal nucleus. Female cement gland close to anterior edge, depth almost touching propodium (Figure 22e: cl).

Pallial cavity: (Figure 22b–c) Most features similar to those of preceding species. Those unique to this species are as follows: Siphon (si) proportionally longer, small pallial fold between anterior ends of gill and osphradium (ac), perpendicular to mantle border; cavity slightly shallower, ~3/4 whorl; gill (gi) and osphradium (os) proportionally broader; wider portion of gill close to rectum; gill anterior and posterior ends bluntly pointed; osphradium with uniform width along its length; osphradium less sessile, with base smaller than filaments (Figure 22b: os); Gill filaments relatively tall, tip protruded, right edge straight (Figure 22b: gi).

Circulatory and excretory systems: (Figure 22c–d) Similar to that of preceding species, with following differences: relatively small kidney ventral lobe attached to intestine, forming glandular cover of intestine (Figure 22d: superior kl); presence of dorsal lobe, formed by pair of zigzagging glandular folds surrounding posteriorly and left lobe attached to intestine (Figure 22d: left kl); efferent renal vessel large (rv), connected only to ventral lobe.

Digestive system: (Figures 23a–f, 24a) General organization similar to those of preceding species, with following interesting features: Proboscis retractor muscles thick posteriorly (Figure 24a: mr), mainly in ventral branches; sparse lateral transverse muscles connecting esophageal origin and odontophore (Figure 23b: tm). Odontophore muscles: pair m1l inserted more posteriorly and medially (Figure 24a); retractor set of muscles m2 (m2m, m2a, m2c) relatively thinner and slender (Figure 23b, f); m3l as continuous dorsal cover with longitudinal fibers (Figure 23b); pair m4 as single bundle originated at posterior end of cartilages (Figure 23f); m11a, presence of two pairs of auxiliary ventral tensor muscles of radula (beyond m11), originated on inner surface of m3c, in its posterior region, running anteriorly covered by m9, inserting at end of radular ribbon, ventrally to insertions of pair m11. Odontophore cartilages slenderer, anterior fusion at ~1/5 of their length (Figures 23f, 24a: oc). Radula (Figure 21a–b): central tooth with 7–10 cusps usually of equal size, except lateral cusps slightly smaller, central cusps larger or thicker; rachidian base slightly curved. Lateral teeth outer cusp hook-shaped, inner cusp larger, thicker than cusps 2 or 3; sometimes asymmetric intermediate cusps; base with faint blunt inner cusp. Salivary ducts with small subterminal bulged region (Figure 23d: sp); salivary apertures in lateral region of dorsal folds, in posterior level of oral tube (Figure 23d: sa). Anterior esophagus wide and flattened, smooth inner surface (Figure 23b: ae). Valve of Leiblein well-developed, including transverse glandular fold and long cilia turned anteriorly (Figure 23c, e: vl), no bypass groove. Middle esophagus with clear glandular surface, small longitudinal folds, length ~15% of anterior esophagus (Figure 23c: me). Gland of Leiblein slender and sinuous, ~half of anterior esophagus length and width (Figure 23a, c: gl); duct small, simple, hollow. Posterior esophagus very wide, flaccid walls; internally sparse, narrow longitudinal folds (Figure 23a, c: ep). Stomach as blind sac, ~1/3 whorl long, ~half local visceral width; posterior end bluntly pointed; walls thin; inner surface with sparse longitudinal, narrow folds directed toward intestine (Figure 24b: st); single small duct to digestive gland in esophageal insertion (Figure 24b: dd). Anus wide, shortly projected (Figures 22c, 24d: an).

Genital system: (Figure 24c–e) Most characters like those of preceding species. Distinctions following. Male with seminal vesicle narrow, as simple zigzagging wide tube along ~1 whorl (Figure 24c: sv). Prostate simple, short (~1/3 length of seminal vesicle), elliptical (Figure 24c: pt). Penis (Figures 21c–d, 22d, 24c, e) relatively narrow, weakly narrowing along its length, distal half flattened; tip rounded; penis duct narrow, weakly zigzagging along penis middle region (Figure 24e: pd); papilla subterminal, very small (Figure 24e: pp). Pallial oviduct (Figure 24d) preceded by gonopericardial duct (go) inserting close to visceral oviduct (vo); capsule gland (cg) as continuation from albumen gland (ag), separated by loose ingesting gland (ig); albumen with ~60% of capsule gland length, but broader than it. Vaginal atrium (Figure 24d: vg) ~1/6 of pallial oviduct length, walls flaccid, hollow, tapering toward pore. Female pore as simple, longitudinal, small aperture (Figure 24d: fp), located posterior and to right of anus.

Central nervous system: (Figure 24f–g) Most characters similar to those of preceding species. Cerebral commissure (cc) narrow, short (slightly shorter than each cerebral ganglion width). Shallow constrictions between dorsal and ventral set of ganglia. Small orifice between both cerebral/pleural set and both pedal ganglia; anteriorly edged by apparent extra cerebro-pleural commissure (Figure 24f). Buccal ganglia (bg) lacking clear commissure between both. Subesophageal/visceral ganglion (ge) small, spherical, connected by narrow nerve with ~double nerve ring length.

Habitat: Intertidal, in sandy and sandy-mud beaches.

Distribution: Rio de Janeiro (~23°S), Brazil to Miramar, Buenos Aires province (~38°S), Argentina.

Material examined: BRAZIL. Rio de Janeiro; Recreio Dos Bandeirantes, MNRJ 9104. Santa Catarina; Florianópolis, MZSP 51771, 2 spm, MZSP 51659, 1 spm, Praia da Armação, MZSP 51322, 2 spm. Rio Grande do Sul; MACN-In 25624, 1 spm; off Rio Grande, USNM 654363, in 25 m, 2 spm; Tramandaí, MZSP 33413, 4 spm, MZSP 52160, 8 spm, MNRJ 6051, 2 spm, USNM 710317, 4 spm; Torres, MZSP 16131, 3 spm, MZSP 77556, 2 spm; Pinhal, MZSP 27314, 2 spm; São Jose do Norte, MNRJ 1156, 2 spm; Tamandaré, MNRJ 2928, 2 spm; Ponta da Cidreira, MNRJ 9332, 3 spm. URUGUAY. Rocha; USNM 381150, 11 spm; Chuy, barra del arroyo, USNM 875579; La Coronilla, MZSP 33408, 23 spm, MACN-In 28772, 6 spm, MZSP 51616, 2 spm; Cabo Santa Maria, MNRJ 1771, 2 spm, MNRJ 6541, 2 spm; La Paloma, MACN-In 30480, 5 spm, MACN-In 30171, 2 spm. Maldonado; Punta del Este, MACN-In 15375, 34°55′S 55°19′W, 20 m, 1 spm. ARGENTINA. Buenos Aires; Villa Gesell, MACN-In 29373, 6 spm; Mar del Plata, MACN-In 9363–10, 5 spm, MACN-In 10240, 2 spm; Miramar, MACN-In 8451–25, 1 spm, MACN-In 8421–25, 2 spm.

3.7.1 Distinctive description

Shell: (Figures 25a–d, j–l, 26a) Medium (up to 57 mm), fusiform. Color reddish brown. Protoconch paucispiral of 1 1/2 to 2 whorls, 1.6 mm wide in second whorl (Figure 26f–h). Sculpture wanting, except for growth lines. Teleoconch of 6–7 slightly convex whorls, spire shorter than 1/2 of shell length. Suture well defined, impressed; 2–3 subsutural spiral cords, sometimes vanishing, very weak. Aperture large, sub elliptic, more than half of total shell length. Parietal callus very weak, but visible (Figure 25a, d, g, j). Inner lip shallowly concave; siphonal inflexure weak. Outer lip simply convex (Figure 25b, h).

Head-foot and operculum: (Figures 26a–b, 27a, e) General features similar to preceding species. Epipodial tentacle small, preceded by medial white region (Figure 26b). Females with cement gland close to anterior end of sole (Figure 27e: cl); relatively short, ending far from hemocoel (Figure 27f: cl). Operculum more rounded, mainly close to nucleus (Figure 25e–f).

Pallial cavity: (Figure 27b, g) Most attributes like those of preceding species, with a few distinctions: Siphon (si) relatively shorter, stubby. Gill (gi) and osphradium (os) relatively shorter and broader; right edge of gill close to tectum. Gill filaments low, with right edge highly convex (Figure 27g: gi). Osphradium with base narrower than filaments (Figure 27g: os).

Circulatory and excretory systems: (Figures 27b, 28e) Characters similar to those of preceding congeneric species, except for single kidney lobe, not organized in folds (Figure 28e: kl).

Digestive system: (Figures 27c–d, 28a–e) Most attributes alike those of preceding congeneric species, distinctive features following. Buccal mass with lateral transverse muscles very developed (Figure 27c: tm). Odontophore with narrow and thin pair m1l (Figure 27c), originating in septum between esophagus and odontophore, running posteriorly at short distance from median line, covering m3c, multiple insertions distributed in postero-dorsal region of odontophore surface; narrow and thin pair m3l, similar to m1l, but originated from lateral surface of odontophore in level of esophageal origin (Figure 27c: m3l); m3c and m6 relatively shorter, keeping free ~1/3 of cartilage length (Figure 28b–c); pair m4 separated in 5–6 separated, narrow bundles (Figure 28b), main posterior branch (m4), another smaller set antero-lateral (m4a); pair m11 relatively thick and broad. Radula (Figure 26d–c): central tooth with 9 cusps of similar size, last two cusps of each margin smaller; rachidian base curved. Lateral teeth with outer cusp large, hook-shaped; inner cusp larger than 3, similar sized, intermediate cusps. Lateral teeth base with blunt inner cusp weakly developed. Salivary ducts possessing subterminal bulged portion (Figure 28a: ss); salivary aperture in lateral side of oral tube, in its posterior level (Figure 28a: sa). Anterior esophagus relatively simple, wide, flattened (Figure 27c, d: ae). Inner surface of entire esophagus with longitudinal, low, narrow folds, slightly more numerous in posterior esophagus (Figure 28d). Valve of Leiblein well-developed, complete, with transverse glandular fold and long cilia (Figures 27d, 28d: vl). Middle esophagus with ~1/3 of anterior esophagus length. Hollow gland of Leiblein relatively long, transversely folded on one side; aperture simple (Figure 28d: gd). Posterior esophagus wide, walls thick, ~as long as anterior esophagus (Figure 28e–f: ep). Stomach (st) with slightly bilobed posteriorly bulged region, walls thick but weakly muscular, but possessing strong gastric muscle (Figure 28e: sm) originated in columella close to end of columellar muscle, running for a short distance up to ventral wall of stomach. Duct to digestive gland single, wide (Figure 28e: dd), located close to intestinal origin.

Genital system: Most features similar to preceding species, except for following: Male with seminal vesicle of medium size (Figure 28f: sv), very narrow caliber; no detected gonopericardial duct. Prostate as simple bulged region in middle portion of pallial vas deferens, preceding its crossing to pallial floor (Figure 28f: pt). Penis (Figures 27a, 29a: pe) possessing elliptical penial gland in dorsal side, from its middle level up to its tip (Figure 29a: pn); penis papilla very small, subterminal (Figure 29a: pp). Female with shallow constriction between albumen and capsule glands (Figure 27b: ag, cg), with albumen gland ~half of capsule gland. Genital atrium with small muscular bursa copulatrix (Figure 27b: bc) in its ventral side. Female aperture as simple transverse pore (fp).

Central nervous system: (Figure 29b–c) Closely similar to preceding species, but with cerebral commissure short, broad, and rounded (cc). Pair of buccal ganglia very small (bg), located close to each other.

Habitat: This is a locally common species that hides buried in sandy beaches during low tide. It can be found because of a low bulge where the animal waits for the rising tide. Averbuj and Penchaszadeh (2016) described the reproductive biology of this species.

Distribution: South of Santa Cruz province, to Tierra del Fuego Is., in Argentina to Punta Arenas, Straits of Magellan in Chile.

Material examined: ARGENTINA. Santa Cruz; San Julián, MACN-In 9200–5, 1 spm, MACN-In 9040–22, 1 spm. Tierra del Fuego; USNM 126896, 1 spm; San Sebastián, MACN-In 12576, 6 spm; Punta Maria, Rio Grande, MACN-In 35385, 20 spm, MZSP 37899, 24 spm; Rio del Fuego, MACN-In 12574, ~80 spm; Bahía San Martín, MACN-In 12578, 1 spm; Punta Sinaia, MACN-In 12577, 3 spm; Ushuaia, MZSP 12574, 1 spm, MZSP 52158, 1 spm; Cabo Peñas, MACN-In 12575–1, 7 spm. CHILE. Magallanes; Bahia Gregorio, USNM 102533, 15 spm, USNM 96528, 1 spm; Punta Arenas, MACN-In 12135–1, 3 spm; Isla Dawson, MACN-In 12135, 2 spm, MACN-In 14135, 3 spm; Straits of Magellan, San Gregorio, MNRJ 1563, 2 spm.

Remarks: King (1832) described this species without illustrating it. He did not notice the previous usage of the name by Gmelin (1791), making his name a homonym. It was later figured and described as Buccinum paytense by Kiener (1834) and as Buccinum citrinum by Reeve (1847). Kiener (1834: 17) cited Valenciennes as author of the species; however, the latter author never published any mention of B. paytense. It was erroneously recorded from Payta, Perú, but it was never recorded further north than Punta Arenas, in the Chilean Pacific.

3.8.1 Distinctive description

Shell: (Figure 30a–p) small to medium size (to 31 mm), fusiform. Protoconch paucispiral, of 2 globose, smooth whorls. Teleoconch up to 7 weakly convex whorls, spire around 1/2 of total shell length. Suture well defined, impressed. Sculpture 3–4 subsutural spiral lirae present in most of specimens, vanishing in middle of whorl, reappearing at base of last whorl (Figure 30c, f, h–i, n–o). Aperture large, shorter than half of total shell length. Parietal callus weak (Figure 30a, d, g, j, l, p); inner lip weakly concave; siphonal inflexure relatively strong. Outer lip profile almost straight (Figure 30b, e, k, m).

Head-foot and operculum: Most features similar to those of preceding species (Figure 32b). Colorless, with epipodial tentacle well-developed (Figure 31d: ed). Operculum elongated, pointed close to nucleus (Figure 30q–r).

Pallial cavity: (Figure 32a) Attributes alike those of preceding species, with following special features: Siphon very larger (si). Gill (gi) and osphradium (os) with anterior and posterior ends more sharply pointed. Wide space between gill and rectum. Gill and osphradial filaments similar to B. deforme.

Circulatory and excretory systems: (Figure 32a) Similar to preceding species. Heart proportionally smaller (ve). Kidney lobe with two flaps attached to intestine (ki), transversely folded.

Digestive system: (Figures 32c–d, 33) General characters similar to those of preceding species. Interesting features following. Transverse lateral muscles connecting esophageal origin and odontophore composed of more sparse fibers (Figure 33b: tm). Odontophore muscles: pair m1l inserted in middle level of odontophore length (Figure 33b: m1l); ventral pair m3l broad (Figure 33b); pair m4 divided into three portions, larger bundle originated at posterior end of cartilage, smaller bundle originating preceding posterior 1/4 of cartilages (Figure 33c–d), another very small bundle originating in median side of main bundle (Figure 33e: m4); pair m9 divided into two separated bundles, anterior one inserted at middle length of radular sac (Figure 33c). Pair of odontophore cartilages slenderer, fused portion shorter than 1/4 of length (Figure 33c–d: oc). Radula (Figure 31a–c) central tooth with 7–10 cusps, usually of same size, except for usually smaller lateral cusps. Rachidian base curved. Lateral teeth with outer cusp hook-shaped; inner cusp larger, thicker than 2 intermediate cusps; lateral teeth base with very weak blunt inner cusp. Pair of salivary ducts possessing bulged subterminal portion (Figure 32d: ss); salivary aperture on medial edge of dorsal folds, at middle length of oral tube (Figure 32d: sa). Portions of esophagus similar to those of B. paytense (Figures 32c, 33a: ae, me, ep); inner surface with longitudinal, irregular, narrow folds. Valve of Leiblein complete, lacking bypass (Figures 32c, 33a: vl). Gland of Leiblein small, anterior half hollow (Figure 33a: transverse section), with 5–6 longitudinal, glandular folds; duct very short (gd) simple. Stomach with non-muscular walls (Figure 32a: st), as deep blind-sac, ~1/3 whorl long; pair of small ducts to digestive gland located in esophagus-intestine intersection (Figure 32a: dd).

Genital system: Most structures similar to those of preceding species, remarkable features following. Male with seminal vesicle of medium size. Prostate like that of B. paytense. Penis marked by sudden bottleneck portion, producing slender, elongated distal region of ~1/3 length of penis (Figures 32b, 34a). Penis duct (pd) convolute, running closer to right side, except for slender distal portion, containing duct narrow, straight, running centrally; penis apex blunt, flattened; papilla small, subterminal (Figure 34a: pp). Female with clear constriction separating albumen and capsule glands (Figure 34b: ag, cg), capsule gland ~twice length of albumen gland. Vaginal atrium (vg) relatively long, ~1/4 of total pallial oviduct length, tapering toward female pore; brown triangular portion of ingesting gland in its posterior region, small muscular concavity in its right-side corresponding to a small bursa copulatrix. Female pore (fp) simple.

Central nervous system: (Figure 34c–d) As concentrated and with similar attributes as in preceding species. Cerebral commissure broad and short (cc). Pair of buccal ganglia apparently fused with each other (bg). Visceral ganglion located posteriorly at a distance equivalent to nerve ring length (Figure 34d: vg).

Habitat: rare, usually subtidal up to 30 m depth.

Distribution: Angra dos Reis, Rio de Janeiro, Brazil to Bahía San Blas, Buenos Aires province, Argentina.

Material examined: BRAZIL. Rio Grande do Sul; Pinhal, MZSP 27314, 2 spm; GEDIP expedition MZSP 33750, 1 spm, MZSP 33898, 2 spm, MZSP 57522, 5 spm; off Mostardas, 31°09′S, 50°43′W, 21 m, MZSP 51405, 4 spm (sta. 1725). URUGUAY. Rocha; La Paloma, MZSP 51406, 1 spm, MACN-In 28784, 2 spm, MACN-In 30481, 1 spm, MACN-In 30487, 1 spm, MACN-In 30171–2, 2 spm, MNRJ 6543, 2 spm, MACN-In 15151, 1 spm, MNRJ 1248, 2 spm, MZSP 78248, 33°54.7′S, 53°17.6′W, 15 m; Cabo Santa Maria, MACN-In 23582, 1 spm. Maldonado; Punta del Este, MZSP 51617, 2 spm. ARGENTINA. Buenos Aires; Necochea, MACN-In 25199, 35°40S 56°03 W, 9.1 m, 14 spm, MACN-In 24202, 35°27′S 54°11′W, 23 m, MACN-In 24146, 36°24S 55°53 W, 16 m, 6 spm, MACN-In 24295, 37°18′S 56°49′W, 8 m, 2 spm, MZSP 10046, 1 spm; Mar del Plata, MACN-In 25364, 17 spm, MACN-In 4660–4, 2 spm; Miramar, MACN-In 9247–14, 12 spm; Monte Hermoso, MACN-In 6619–53, 5 spm, MACN-In 11230–1, 1 spm, MZSP 10052, 16 spm; Arroyo Parejas, MACN-In 11232–1, 3 spm; Puerto Belgrano, MACN-In 11341, 3 spm; Bahía San Blas, MACN-In 20254, 23 spm, MACN-In 20273–3, 1 spm.

Remarks: Buccinastrum uruguayense has been scarcely mentioned in the local or international literature since its original description. Probably it was not easily recognized because of the similarity with young specimens of B. cochlidium and others, one of the locally most common species of Buccinanops. In addition, Ihering (1907: 445) stated that it can be only a local variety of B. cochlidium, an assumption that can justify its absence in subsequent surveys. Despite the size, which is clearly smaller, and the slender spire, the presence of several subsutural lirae in the first whorls (Figure 30h–i, k, n, o) as well as on the base of the last whorl, are distinguishing characters. In addition, the shape and ornamentation of the egg capsules are different from those of B. cochlidium which has a characteristic and unique sculpture on one side. Averbuj and Penchaszadeh (2016) provided some data on the reproductive biology of this species.