Thieleella equatoria ( Hedley, 1899 )

Geiger, Daniel L. & Jansen, Patty, 2004, Revision of the Australian species of Anatomidae (Mollusca: Gastropoda: Vetigastropoda), Zootaxa 415 (415), pp. 1-35 : 26-27

Thieleella equatoria ( Hedley, 1899) : Figures 14 , 18

Scissurella equatoria Hedley, 1899: 551–552 , fig. 61.

Scissurella aequatoria [sic]: Hedley, 1903: 330.

Scissurella equatoria: Thiele, 1912: 20 , pl. 3, fig. 4 [copy of figure in Hedley, 1899].

Anatoma equatoria: Habe & Kosuge, 1964: 4 .

Type material. HOLOTYPE ( AMS C.5639), 3 x 2.68 mm (H x W).

Type locality. Tutaga Islet, Funafuti Atoll, 200 fms. [= 365 m, 8.617°S, 179.083°E,] (OD).

Etymology. Most likely named for its occurrence near the equator.

Description. Shell globular, medium size (to 3 mm: holotype). Protoconch almost 1 whorl, with reticulate sculpture, no varix. Teleoconch I slightly more than 1/2 whorl, with 15 axials, spirals not visible. Teleoconch II with up to 3.5 whorls (holotype: fide Hedley, 1899), axials 75 (1.83 mm specimen: figure 13) to 85 (3 mm specimen: holotype) on body whorl. Spirals on shoulder extremely faint, on base very fine, forming reticulate interstices with axials. Umbilicus open, deep, sloping continuously from base. Selenizone at periphery, strong keels, axials on keels finer and more numerous than axials on shell proper; margins of slit parallel. Aperture rounded, flared towards umbilicus. Animal unknown.

Differential Diagnosis. Anatoma turbinata has flocculant protoconch sculpture compared to a reticulated one, is more turreted, has a smaller aperture compared to overall shell size, has fewer axials, and more prominent spirals.

Specimen records. Off NE point, Christmas Island, Australia, 183 m (AMS C.405015, 1: shell only).

Remarks. This species is currently only known from two specimens, the holotype and the additional specimen figured here ( Fig. 13 ).

Figures

FIGURE 13. Anatoma tobeyoides paratypes. AMS C.402673. W of D’Entrecasteaux Channel, TAS, Australia. B. AMS C.402674. Off Moreton Bay, QLD, Australia. C. AMS C.406337. Off Long Point, N of Bicheno, TAS, Australia. Scale bars shell = 200 µm. Scale bars spire and protoconch = 50 µm.

FIGURE 14. Thieleella equatoria. AMS C.405015. Off NE point, Christmas Island, Australia, 183 m. Scale bar shell = 200 µm. Scale bars spire and protoconch = 50 µm.

FIGURE 18. Distribution maps of Australian species of Anatomidae. Circle with star: type locality. Solid dots: specimen records. Squares: literature records.