Trophon plicatus (Lightfoot 1786)

“Trophon plicatus. (Lightfoot, 1786)

(Figures 22-42)

Le Sabot Magellanique Favanne, 1780: 342, pl. 79, fig. I., nomen nudum.

Buccinum laciniatum Martyn, 1784: fig. 42, nomen nudum.

Murex plicatus Lightfoot, 1786: 104.

M. lamellosus Martyn.—Gmelin, 1791: 3536; Wood and Han­ley, 1856: 133, pl. 27, fig. 100

Polyplex gracilis Perry, 1811: pl. 9, fig. 4.

Fusus laciniatus Martyn.—Reeve, 1847: spec. 14, figs. a, b, c.; Hupé in Gay, 1854: 168; Gould, 1861: pl. 16, fig. 278.

Trophon laciniatus Martini.—H. and A. Adams, 1853: 77, pl. 8, figs. 3 a, b.; Kobelt, 1878: 280, pl. 72, figs. 6, 7; Tryon, 1880: 143, pl. 31, figs. 330-332. Rochebrune and Mabille, 1889: H.53; Strebel, 1904: 199, pl. 3, figs. 1-8; Lamy, 1906: 3; Strebel, 1908: 37; Castellanos, 1970: 74, pl. 5, fig. 1.

?Trophon antarcticus Philippi, 1868: 225 (sensu Tryon 1880).

T. lacineatus Martyn. Sowerby II, 1880: pl. 404, fig. 13.

T. (Stramonitrophon) laciniatus (Martyn).—Powell, 1951: 156, fig. L, 86.

T. (Stramonitrophon) lamellose (Gmelin).—Dell; 1971: 212.

T. plicatus (Lightfoot, 1786).—Rehder, 1967: 20; Cernohorsky, 1977: 117, fig. 18; Vokes, 1991: 7, fig.; 1991b: 9, figs. 14-16; 1992: 3, figs. 2, b, c, d.; Castellanos and Landoni, 1993: 5, figs. 16, 15, 22.

Description: Shell of medium to large size (to 50 mm), smooth, fusiform, thin, somewhat chalky; proto­conch smooth of 2½ whorls; teleoconch of 6 shouldered whorls, spire less than ½ of total shell height. Spire angle about 50°; suture impressed; subsutural ramp straight, aperture small, ovoidal, interior pale brownish; anterior siphonal canal long (more than half height of the aper­ture), narrow, curved, open; umbilicus absent; outer lip rounded with reflected edges; inner lip curved, adpressed. Axial ornamentation of irregular, low lamellose varices in the first whorls, that become 8-10 real lamellae in the last ones. Lamellae growing over the entire whorl, but attached to the shell, sometimes curving adaxially. Lamellae ending in a peripheral spine, in some specimens growing adapically. Spiral ornamentation poorly developed to almost smooth, sometimes consisting of 6 weak cords on the base of the last whorl and the back of the siphonal channel. Regular, very weak growth lines present throughout shell.

Shell ultrastructure composed of two layers; inner­most layer (25% of shell thickness), composed of cola­brally aligned crossed lamellar aragonite, outer layer thick (75% of shell thickness) with amorphous calcite (Figure 42).

Operculum oval, with terminal nucleus. External surface covered by concentric, irregular, growth lines. Inner surface attachment area with two or three horseshoe-shaped scars, glazed rim present in all specimens (Figure 36).

Animal of medium size relative to shell. Mantle large, mantle roof thin. Cephalic tentacles broad in basal half, flat, blunt, with rounded large black eyes in the middle; mantle edge thickened, smooth; pallial organs arranged as in other rachiglossans; brown osphradium less than half of ctenidium length, slightly asymmetrical, with 50 -55 leaflets per side; ctenidium as wide as osphradium, containing triangular leaflets. Hypobranchial gland brownish and inconspicuous, rectum to the right of hypobranquial gland.

Proboscis pleuroembolic, long, broad. Radular ribbon extending beyond rear of buccal mass, long (0.69 × ap­erture height vs. 0.78 × aperture height in Trophon geversianus). Esophagus loops beneath buccal mass, where esphagus receives embedded ducts of salivary glands an­terior to a small Leiblein valve. Esophagus curving dis­tinctly and running along entire side of gland of Lei­blein. Esophageal glands ("Glandule framboise") whitish in color, posterior to nerve ring slightly marked on the external side of the esophagus. Large salivary glands en­veloping Leiblein valve and accessory salivary glands. Ac­cessory salivary glands distinctly large, sometimes dark-colored, tubular, compact, coiled, embedded in salivary glands. Gland of Leiblein conspicuous, brown, ending in a medium size blind duct and very small ampulla.

Radula rachiglossan with rachidian teeth wide (~150 µm), central cusp thin, large; lateral cusps wider and slightly shorter than central cusp, with inner edge straight; with sharp straight denticle in upper third of internal edge of lateral cusp, external edge with 6 very well defined denticles, always present. Base of rachidian tooth sinuous, sliding beneath base of next tooth. Mar­ginal area with single conspicuous cusp. Lateral teeth with single, long and narrow cusp, slightly attached basal plate. Cusps of rachidian teeth pyramid-like in lateral view (Figures 38-40).

Male and female organs as in Trophon geversianus (see Harasewych, 1984).

Type Locality: Islas Malvinas.

Type Material: Probably lost. According to Dance (1966) part of the material from the Portland Catalogue is in London (BMNH), however this is not the case of T. plicatus.

Additional Material Examined: 52°30' S, 67°14' W, 2 D, R/V ELTANIN Cruise 11, Sta. 980, 14 February 1964, 82 m (USNM 870535); 53°35' S, 69°45' W, 1 D, R/V HERO Cruise 692, Sta. 404, 37-46 m (USNM 901620); 52°56' S, 75°00' W, 1 D, R/V ELTANIN Cruise 11, Sta. 958, 5 February 1964, 92-101 m (USNM 870423); 53°06' S, 67°04' W, 3 D, R/V HERO Cruise 702, Sta. 450, 5 March 1970, 86 m (USNM 901622); 53°39'24" S, 70°55'30" W, 1 D, R/V HERO Cruise 702, Sta. 467, 25 April 1970, 24 m (USNM 901623); 52°35' S, 65°08' W, 1 D, R/V ELTANIN Cruise 11, Sta. 976, 13 February 1974, 128 m (USNM 870525); 46°04' S, 83°55' W, 1 A, R/V ELTANIN Cruise 25, Sta. 326 9 October 1966, 298 m (USNM 901621); 53°48.7' S, 70°24.1' W, 1 D, R/V HERO Cruise 702, Sta. 489, 29 April 1970, 13-18 m (USNM 901624); 53°32' S, 64°57' W, 2 A, R/V ELTANIN Cruise 11, Sta. 974, 12 February 1964, 119-­124 m (USNM 881960); 53°39' S, 70°55.5' W, 1 A, R/V HERO Cruise 702, Sta. 466, 20 m (USNM 901754); Ba­hia Golondrina, Ushuaia, 1 A, (MLP 27202); Rocamora, Ushuaia, 1 A, 8-10 m (MACN-In 36053); Bahía Ensen­ada, Ushuaia, Tierra del Fuego, (MACN-In 36033); 45°07' S, 65°W, 1 A, Discovery Station WS788, 13 De­cember 1931, 82-88 m (AK 133035) illustrated in figs. 28-29; Comodoro Rivadavia, 17 D (MACN-In 9032-16); 54°34' S, 64°00'18" W, 1 D, 1 A, R/V HERO Cruise 715, Sta. 870, 24 October 1971, 84 m (USNM 881128); Bahía Buen Suceso, 1 A, 23 October 1941, (MLP27230); Cabo Colnett, Isla de los Estados, 1 A, R/V HERO Cruise 712, Sta. 853, 20 October 1971, 91 m (USNM 869720); 2 D, 78 m (USNM 96176); Orange Harbor (USNM 5676); Paso Richmond, Tierra del Fuego 55 m, (MACN-In 24940); 55°7' S, 66°33' W, 82 m (MACN-In 23938); Ti­erra del Fuego (MACN-In 5240-2); Punta Peñas, San Julián, Santa Cruz province, Argentina, 4 A (MLP 27232); Punta Peñas, San Julián, Santa Cruz, Argentina, 1 A (MLP 27212); Puerto San Julián, Santa Cruz prov­ince, Argentina (49°15' S, 67°39' W), 4 A, 2-3 m (MACN-In 36034); 45°55.219' S, 73°39.522' W intertid­al, Islet NE shore of Isla Huemules, Golfo Elefantes, Chile (BMNH 19990384).

Distribution: This is a typical species from the Ma­gellanic province. It has been recorded from Peninsula Valdés to Tierra del Fuego in Argentina and Chile to 49°S in the north (Reid and Osorio, 2000).

Remarks: The authorship of the name according to Dance (1962) and Rehder (1967) should be credited to J. Lightfoot, the anonymous compiler of the "Catalogue" where the name was used for the first time, not to So­lander.

There is an interesting range of conchological varia­tion in Trophon plicatus, from almost smooth specimens to highly lamellate. However, the profile is always slen­der. Trophon bahamondei McLean and Andrade, 1982, is a morphologically similar species, with peripheral spines and shallow lamellae. On the other hand, T. ba­hamondei has no spiral ornamentation and Trophon pli­catus has 6 weak cords on the base of the last whorl and the back of the siphonal canal.

The gross anatomy is that customary for most Pata­gonian Trophoninae. However, a distinctive anatomical feature is the morphology of the accessory salivary glands, which are compact, tubular, somewhat coiled and large, and completely embedded in the salivary glands. Most Patagonian Trophoninae (e.g., T. bahamondei as well as T. geversianus), have small, kidney-shaped, ac­cessory salivary glands.

Radular features of T. plicatus are clearly different from T. bahamondei (see Figures 26-27). The latter has a distinctive small cusp on the outer margin of the lateral cusp on the rachidian teeth. In addition, the rachidian base is thinner and wider.

Trophon antarcticus Philippi, 1868, is probably a syn­onym according to Tryon (1880); however, the type ma­terial is missing and the description is rather obscure.

Powell (1951) described the subgenus Stramonitro­phon to include only T. plicatus [(as T. laciniatus Martyn, nomen nudum rejected by Opinion 456 (ICZN, 1957)] a species with Stramonita-like radula, i.e., rachidian teeth with three cusps, where the marginal side of the lateral cusps bears several denticles. This radula illus­trated by Powell (1951: 194, fig. L, 86) was dissected from the specimen illustrated in figs. 28-29. The radular morphology of T. plicatus is different from that of T. geversianus. However, Coronium coronatum (Penna-­Neme and Leme, 1978) and T. acanthodes Watson, 1882, bear the same denticles on the lateral cusps of the rachidian teeth. This appears to be a common feature in several Trophoninae from the southwestern Atlantic.

The shell of Trophon iarae Houart, 1998, shows some similarity with some specimens of T. plicatus. It was based on only two specimens collected by fishing boats apparently from Brazil and off Uruguay. The anatomy and soft parts of T. iarae remain unknown. The radula apparently has been illustrated by Calvo, 1987 (although according to Houart, 1998: 127, there is no certainty about the identity of the specimen from where this rad­ula was taken). In any event, this illustration does not allow for a detailed comparison with other species. Fur­ther comments about the validity of this species or its affinity with other species of Trophon mostly depends on anatomical data which are not available.

Houart (1998: 127) mentioned the specimen of T. pli­catus illustrated by Cernohorsky (1977) from Lively Is. (Malvinas Is.) as belonging to his new species, T. iarae. However, Cernohorsky's specimen could be easily in­cluded in the range of geographic distribution and mor­phological variation of T. plicatus. He also illustrated two specimens of T. patagonicus as T. plicatus (Figures 8-10 in Houart, 1998).”

(Pastorino, 2005:60-64)

Trophon plicatus is a species of sea snail, a marine gastropod mollusk in the family Muricidae, the murex snails or rock snails.

Trophon plicatus là một loài ốc biển, là động vật thân mềm chân bụng sống ở biển trong họ Muricidae, họ ốc gai.