Thaleia nisonis (Dall, 1889b)

(Figures 22 A–F, 23A–C)

Benthonella nisonis Dall, 1889b: 283 .

Thaleia nisonis: Warén (1979: 284, figure 5); Absal„o et al. (2003: 324, figs. 4–5).

Type material. Holotype USNM 93802.

Type locality. USA: off Lousiana, UFSC stn. 2384 (28°45′00″N 88°15′30″, 1719 m), coll. 03/iii/1885 .

Material examined. Holotype; USA: USFC stn. 2668: USNM 108092 [5 dd]. Bahamas: USFC stn. 2654 (27°57′30″N 77°27′30″W, 1207 m), coll. 18/v/1886: USNM 330620 [1 dd]; Cuba: Blake stn. 30 (24°33′N 84°34′W, 1770 m), coll. 01/i/1877: USNM 94289 [2 dd]; USFC stn. 2352 (22°35′N 84°23′W, 847 m), coll. 21/i/1885: USNM 323107 [1 dd]. Brazil: Rio Grande do Norte: off Rio Grande do Norte, REVIZEE Nordeste (06°14′04″S 34°52′33″W, 510 m), 26/xi/2001: MNRJ 35263 † [1 dd]; Bahia: Camamu-Almada Basin (14°30′42″S 38°44′02″W, 1400 m): MNRJ 34498 † [1 dd]; Rio de Janeiro: Oceanprof II stn. A-13: IBUFRJ 16639 † [1 dd]; Oceanprof I stn. 84: MNRJ 33512 † [1 dd]; Oceanprof II stn. 74: IBUFRJ 17317 † [2 dd]; Oceanprof II stn. 68: IBUFRJ 17570 † [1 dd].

Measurements. Holotype USNM 93802, 10 whorls (protoconch partially broken), SL= 9.1 mm; BWL= 4.1 mm; AL= 2.4 mm; SW= 4.0 mm; AW= 1.8 mm. MNRJ 33512†, ~10 whorls, SL= 4.3 mm; BWL= 2.1 mm; AL= 1.3 mm; SW= 2.0 mm; AW= 1.1 mm. MNRJ 34498†, ~8 whorls, SL= 3.6 mm; BWL= 1.8 mm; AL= 1.1 mm; SW= 0.9 mm; AW= 1.7 mm.

Remarks. Warén (1979) provided a redescription of the shell and of the soft parts of Thaleia nisonis . Absal„o et al. (2003) recorded T. nisonis for the first time in Northeast and Southeast Brazil. One of the shells recorded by Absal„o et al. (2003) was collected in 50 m (IBUFRJ 12699), an odd shallow water record. This lot was not located and we consider this record doubtful.

Thaleia nisonis is a peculiar species and easily distinguished from other deep water eulimids by the brownish protoconch (Figure 23A) and by the sculpture on the protoconch (Figure 23B) and teleoconch (Figure 22C). Other genera occurring in the deep Atlantic have a brown protoconch: Batheulima Nordsieck, 1968, that also presents axial sculpture on the protoconch and teleoconch (Bouchet & Warén 1986: 334); and Fuscapex Warén, 1981a, which usually does not have sculpture on the protoconch, except for F. microcostellata Bouchet & Warén, 1986 (Bouchet & Warén 1986: 325). Despite these similarities, T. nisonis can be distinguished from any of the species in these other genera by the presence of a spiral thread on the upper region of the protoconch whorls and the small denticles present on the thin axial lines of the protoconch (Figure 23B, C). These denticles resemble spiral sculpture (Absal„o et al. 2003).

Geographical distribution. USA: Florida (Off Fernandina); Gulf of Mexico; Bahamas; Cuba (Warén 1979); Brazil: Rio Grande do Norte state (present study), Bahia and Rio de Janeiro states (Absal„o et al. 2003, present study).

Bathymetric distribution. From 510 m to 1950 m.