Trophon clenchi (Carcelles 1953)

“Trophon clenchi (Carcelles, 1953)

(Figures 101-114)

Murex clenchi Carcelles, 1953: 7, figs. 23-28; Castellanos, 1970: 80, pl. 5, fig. 7; Fair, 1976: 31, fig. 15; Vokes, 1992b: 24; Rios, 1994: 115.

Poirieria (Poirieria) clenchi (Carcelles).—Vokes, 1970: 18.

Description: Shell medium in size, delicate, thin, chalky, translucent white, protoconch known only from the holotype, asymmetrical, globose, of 2-2½ whorls; teleoconch of 5 shouldered whorls; spire short, less than ¼ of total shell height. Spire angle about 45º (without spines); suture impressed, subsutural shelf short, straight; aperture suboval, interior glossy white; anterior siphonal canal very long (longer than the aperture height), deep and slightly curved in the beginning and then straight, open but narrow; outer lip sharp, inner lip somewhat protruding, adpressed. Axial ornamentation of 7-9 regular axial lamellae growing across entire whorl surface, but attached to shell producing open, long and regularly spaced spines along periphery. Spiral ornamen­tation of 4-5 rounded cords on lower half of first whorls, becoming more than 20 in the last. Delicate growth lines present on entire shell surface.

Shell ultrastructure composed of two layers following the common pattern of the genus: innermost layer (40% of total thickness of shell) composed of crossed lamellar aragonite, outer layer (50%) of amorphous calcite. Sometimes, depending on the fracture mode, a basal aragonitic layer can be observed.

Radulae rachiglossate, rachidian teeth with three median cusps, the central one the larger and the lateral ones with a denticle, attached to the upper third of the interior margin of the lateral cusp; external margin with 2-3 obsolete denticles. Rachidian base sinuous, with the base offset under the proximal tooth. Marginal cusps sin­gle, never bifid. Lateral teeth curved, thin, with attach­ment area also thin (Figures 113-114).

Operculum triangular or suboval tear-shaped, attach­ment area elliptical, with horseshoe shape scars.

Type Material: 38°24' S, 55°36' W, off Mar del Plata, in 89.6 m, holotype and paratype (MACN-In 25146).

Additional Material Examined: 51°58' S, 56°38' W, 3 D, R/V ELTANIN Cruise 7, Sta. 558, 646-845 m (USNM 901774), 41°51' S, 57°34' W, collected by Uru­guayan fishermen, June 2002, 1062 m, 1A, MACN-In 36270; approximately 45°10' S, 57°20' Uruguayan fish­ermen, 1 A, MACN-In 36269; 54°50' S, 63°50.5' W, 2.5 miles south Punta Fallows, Isla de los Estados, Tierra del Fuego, 1 A, R/V HERO Cruise 715, Sta. 715/879, 28 October 1971, in 342-353 m (LACM 71-331).

Distribution: Known from off Buenos Aires province, Patagonia and Isla de los Estados, in 90-1050 m depth.

Remarks: Carcelles (1953) described Murex clenchi from two shells he received from the crew of the ARA BAHÍA BLANCA, an Argentine Navy ship that occasionally collected material for the collection of the Museo Ar­gentino de Ciencias Naturales (MACN). Both holotype and paratype were collected from the continental shelf off Buenos Aires province. This material remained housed at the MACN until it was sent on loan and it appears to have been lost for almost 30 years (see Cas­tellanos, 1986). The return of the material to MACN made the type material again available for studies. Per­haps because of these facts, the ordinary quality of the illustration and the absence of soft parts, the species was always reluctantly considered as the southernmost rep­resentative of the genus Murex.

E. H. Vokes, in a fundamental paper published in 1970, stated that Murex clenchi belongs in the genus Poirieria sensu stricto. Rios (1994) considered M. clenchi as an anomalous specimen of Trophon acanthodes Wat­son, a species that slightly resembles some specimens of M. clenchi (e.g., the paratype).

The morphology of the shell as well as the radula and penis of Murex clenchi allow the allocation in the genus Trophon. In fact, this was already suggested by E. H. Vokes (1992b). After studying the material of T. acan­thodes housed at the MACN she proposed that M. clen­chi belongs to Trophon sensu lato and not to Poirieria. It bears no relationship with Poirieria despite some ap­parent shell similarity. As it is shown in Figure 112, Poir­ieria zelandica, type species of Poirieria, has no calcitic layer on the shell but a thick aragonitic one instead (Fig­ure 112a). In contrast, the entire group of Patagonian Trophon (T. clenchi in particular), shows different de­grees of development of the typical calcitic layer on the distinct species.

The range of the very few lots studied falls within the geographic distribution of other species of Trophon. Tro­phon clenchi was known from two quite different geographic and bathymetric areas: off Buenos Aires prov­ince (in about 90 m) and the slope off Patagonia. A new lot is recorded here from Isla de los Estados, which sig­nificantly increases the range of distribution of the spe­cies. It is possible that like other Patagonian species of the genus, T. clenchi would be associated to hard bot­toms, thus hampering the collection of material. Its fra­gility, size, and inadequate sampling of the area adds other reasons for the scarcity of records. It is suggested that these variables accounts for the disjunt recorded distribution of this species. In fact, this species started to be repeatedly collected recently, when the fishery of the Patagonian toothfish (Dissostichus eleginoides) on the Argentinean slope provided the opportunity to catch accidentally entangled specimens (F. Scarabino, pers. comm.).”

(Pastorino, 2005: 71-74)

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

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