Eulimella torquata, Pimenta & Santos & Absalão, 2011

Pimenta, Alexandre Dias, Santos, Franklin Noel Dos & Absalão, Ricardo Silva, 2011, Taxonomic revision of the genus Eulimella (Gastropoda, Pyramidellidae) from Brazil, with description of three new species, Zootaxa 3063 (1), pp. 22-38 : 28-30

Eulimella torquata new species

Figures 19–25

Diagnosis. Eulimella species with a pronounced constriction in the middle of teleoconch whorls, causing them to be bilobed in profile.

Description. Shell tall, elongate turriform, reaching 6.0 mm in length; glossy white. Teleoconch with up to nine whorls, with pronounced constriction at middle of each whorl, caused by spiral furrow marked by highly visible axial growth lines and producing concave, bilobed whorl profile. Suture shallow, rectilinear. Protoconch heterostrophic planispiral, type B with “spiral” shaped suture and ~2.25 whorls; diameter 310µm to 333µm (mean =327µm, n=4). Axial sculpture absent, except for growth lines, visible from third whorl on as strong, short, microscopic axial threads organized in a spiral belt at middle of whorls. Spiral sculpture absent. Aperture ovoid to subquadrate, inner lip slightly projected into parietal region; columella slightly arcuate, without columellar fold. Outer lip thin. Not umbilicate.

Dimensions. Holotype with 6.0 mm length, 1.56 mm width (nine teleoconch whorls), protoconch width: 314 µm, angle to shell axis: 120 o.

Type material. Holotype: MNRJ 13251 , off Bacia de Campos (1,084 m), 24/viii/2001; paratypes: MNHN 24588 , MD 55 sta CB79 [2]; MNHN 24589 , MD 55 sta CB77 [1]; MNHN 24617 , MD 55 sta DC70 [5]; MZSP 101567 , MD 55 sta CB77 [2]; IBUFRJ 19120 , off Bacia de Campos [1]; MNRJ 13095 , off Bacia de Campos (1,080 m), 12/xi/2001, [1]; MNRJ 13096 , off Bacia de Campos (1,080 m), 17/xi/2001 [1]; MNRJ 13252 , type locality [1]; MNRJ13506 , off Bacia de Campos (1170m), 24/viii/2001 [1].

Type locality. Off Bacia de Campos (1,084 m), Rio de Janeiro state, southeast of Brazil .

Etymology. From Latin torquatus = adorned with a collar. An allusion to the spiral constriction in each teleoconch whorl.

Geographic distribution. Restricted to deep water (790 – 1,575 m) localities of southeast Brazilian coast (~19 o S to ~23 o S).

Remarks. Eulimella torquata ( Figs. 19–25 ) has the same general shell shape and dimension as E. smithii (Figs. 1–3, 7, 10) and E. rudis (Figs. 11–12, 16); however, some differences are visible in the sculpture and profile of the teleoconch whorls. Eulimella torquata has a marked spiral groove in the middle of the teleoconch whorls, which resembles a “false suture” ( Figs. 23–24 ). This groove creates a constriction in the middle of each whorl, producing a bilobed profile ( Figs. 20, 23–25 ).

In E. rudis the spiral groove is much less pronounced (Figs. 16–18), and it is inconspicuous in E. smithii (Figs. 7–9). Also the axial threads located in the groove are much stronger in E. torquata ( Figs. 24–25 ) than in any other species.

A very similar spiral furrow is present in the Indo-Pacific Turbonilla mercedesae Peñas & Rolán, 2010 . However, in this species, the first 5–6 teleoconch whorls have axial ribs, and from whorl 6–7 on, the shell surface is smooth with a very similar spiral constriction to that of E. torquata .

Figures

FIGURE 19–25. Eulimella torquata n. sp. 19, 23: whole shells (lengths: 19. 6.0 mm; 23. 5.72 mm); 20: last whorl; 21–22: protoconchs; 24–25: detail of sculpture. 19–21. holotype (MNRJ 13251). 22–25. paratype (MNHN 24588). Scale bars: 19, 23. 1.0 mm; 20. 500 µm; 21–22, 24–25: 100 µm.