Thaleia nisonis ( Dall, 1889b )

Souza, Leonardo Santos De, Pimenta, Alexandre Dias & Barros, José Carlos Nascimento De, 2021, Revision of the deep-sea Eulimidae (Gastropoda, Caenogastropoda) from off Northeast Brazil, Zootaxa 4927 (4), pp. 451-504 : 491-492

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.

Figures

FIGURE 22. A–F. Thaleia nisonis (Dall, 1889b): MNRJ 33512. C. Detail of teleoconch sculpture. Scale bars:A, B, D= 1.0 mm; C= 100 µm; E, F= 500 µm.

FIGURE 23. A–C. Thaleia nisonis (Dall, 1889b): MNRJ 33512. A. Detail of protoconch, frontal view. B. Detail of protoconch surface, frontal view. C. Detail of protoconch, apical view. Scale bars: A= 500 µm; B= 50 µm; C= 100 µm.