Smithsonian National Museum of Natural History

Original Description
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“Trophon emilyae Pastorino, new species

Diagnosis

Shell small, slender, almost smooth; siphonal canal very long, twisted, narrow. Axial sculpture of regular, thin, gentle varices; spiral sculpture of four very weak cords in the first whorls, then obsolete.

Description

Shell small in size (up to 16 mm), slender, fusiform, very thin, translucid; protoconch of one and a half whorls; teleoconch of five mod­erately convex whorls; spire ¼ of total shell length; subsutural shelf faint. Spire angle about 40°, suture abutting; aperture small, its interior glossy white; anterior siphonal canal very long, twisted, narrow; umbilicus closed; outer lip rounded; columellar lip almost indistinct. Axial ornamentation of regular, thin varices, about 8-11 on last whorl, slightly developed, running along whorl surface from adapical suture to siphonal fasciole, weakly projecting outwards along keel. Spiral ornamentation of low, rounded spiral cords, four in the first whorls then obsolete, the entire shell surface covered by regular threads. Regular growth lines cover­ing whorls and lamellae.

Innermost shell layer very thin, comprising about 5% of shell, composed of aragonite (?), with the crystal planes oriented perpendicular to growing edge of shell; second layer arago­nitic crossed-lamellar, representing 95% of shell thickness.

Operculum suboval, completely covering aperture, brownish in color, thin, with terminal nucleus; growth lines covering external surface curved at upper ends; attachment area with two or three horseshoe-shape scars.

Rachiglossan radula with teeth very closely packed; rachidian two times wider than height; central cusp very thin; lateral cusps shorter but of similar thickness to central cusp, denticle between central and lateral cusp very large. Base of rachidian teeth curved, large; marginal area inclined, smooth. Lateral teeth large size, with a thick attached portion.

Etymology

This species is dedicated to Dr. Emily Vokes, of Tulane University, New Orleans, Louisiana (now retired), who helped me with my first steps on Trophon.

Type Material & Locality

Holotype: USNM 896438; R/V Eltanin Station 1343, 567-604 m, collected with rock dredge, 7 November 1964, 54°50'S/29°50'W.

Paratypes: USNM 1003475, from type local­ity, 3 specimen (one with animal); USNM 896441, R/V Eltanin Station 1346, 549 m, 54°49'S-129°48'W, 4 specimens; USNM 898917, R/V Eltanin Station 1345, 915-1153 m. 7 November 1964, 54°50'S/129°48'W, 4 shells, collected with Menzies trawl.

Distribution

Known only from the vicinity of the type locality.

Remarks

The shell morphology of T. emilyae is com­parable to some specimens of T. declinans Watson (Figs. 16, 17) despite the distance be­tween their distributions on the opposite sides of Antarctica (Fig. 44). The shell of T. emilyae is more slender, with a longer anterior canal. The axial lamellae in T. declinans are some­what protruding from the whorl side, whereas in T. emilyae they are never detached from the shell wall. The radulae are also different; the base of the rachidian in T. emilyae is some­what curved, with a long, thin intermediate den­ticle between the central and lateral cusps. The lateral cusps are thinner and longer in the new species (Figs. 10,11). To fix the identity of the taxon (ICZN, 1999: Art. 74.7), the specimen of T. declinans illustrated here in Figures 16 and 17 (NHM 1887.2.9.573) is here designated lectotype. The other three lots with one speci­men each therefore become paralectotypes (NHM 1887.2.9.574, 1887.2.9.575, and 1985041).

Cernohorsky (1977) mentioned the Magel­lanic T. ohlini Strebel, 1904, as being very simi­lar to T. declinans. The type material of T. ohlini, housed in the Zoologisches Institut and Zoologisches Museum der Universität Ham­burg, was studied as part of the complete revi­sion of the genus in progress. Based on the morphology of its protoconch, it is apparently not related to any Antarctic species.”

Table 1. Measurements (in mm), distribution, and depth range (in m) of Trophon emilyae, new species; T. arnaudi, new species; T. septus Watson, 1882; T. scolopax Watson, 1882; and T. cuspidarioides Powell, 1951.

(Pastorino, 2002: 354-357)