Thieleella gunteri ( Cotton & Godfrey, 1933 )

Geiger, Daniel L. & Jansen, Patty, 2004, Revision of the Australian species of Anatomidae (Mollusca: Gastropoda: Vetigastropoda), Zootaxa 415 (415), pp. 1-35 : 27-29

Thieleella gunteri ( Cotton & Godfrey, 1933) : Figures 15–18

Schizotrochus gunteri Cotton & Godfrey, 1933: 23 : pl. 1, fig. 11.

Schizotrochus gunteri: Cotton, 1945: 150 .

Schizotrochus gunteri: Cotton, 1959: 41 , fig. 15.

Scissurella (Anatoma) gunteri: Wilson, 1993: 46 .

Anatoma guntheri [sic]: Jansen, 1999: 49, figs. 10–12.

Type material. HOLOTYPE ( SAM D.10769: Cotton, 1959, Jansen, 1999), 1.5 x 1.1 mm (W x H).

Type locality. Beachport , South Australia, 150 fms. [= 275 m] (OD) .

Etymology. Named after Rev. H. Gunter from South Australia (OD).

Description. Shell globular, medium sized to large (3 mm). Protoconch 3/4 whorls, reticulate sculpture, varix faint, not connecting to embryonic cap, aperture sinusoid. Teleoconch I 0.6–0.85 whorls, 16–22 axials, apical spiral in position of selenizone, interstices with fine growth lines. Teleoconch II 2 2/3 whorls, shoulder with strong axials, approximately 45 on body whorl, approximately 20 fine spirals running over axials. Base with more numerous but finer axials, spirals of equal strength to axials, base sloping continuously into umbilicus. Umbilicus narrow, deep, with indistinct funiculus. Selenizone at periphery, keels elevated but fragile, growth increments faint, not coordinated with axials on shoulder or base. Slit open, margins parallel. Aperture rounded, flared in lower adumbilical portion. Animal unknown.

Differential diagnosis. Anatoma australis from New South Wales, Queensland, and NW and SW Western Australia has axials on the shoulder and on the base of equal strength, while in T. gunteri the shoulder axials are markedly stronger. Anatoma australis also has flocculant protoconch sculpture whereas T. gunteri has a reticulate one. Anatoma tobeyoides from Tasmania, Victoria, New South Wales, and Queensland, also has axials of equal strength on the shoulder and base, a protoconch with a flocculant sculpture, and a teleoconch I of fewer than 0.5 whorls.

Distribution. Tasmania and South Australia, 219–667 m (shells only), sandy and silty bottoms.

Specimen records.

SA. 667 m, off Cape Martin, 38.125S, 140E ( AMS C.402691, 3). 174 m, 40 ml S of Cape Wiles , 35.65S, 136.667E ( AMS C.402690, 20+; AMS C.31845, 20+).

TAS. 212 m, S of Storm Bay , 43.783S, 147.808E ( AMS C.402634, 3) . 570.5 m, 9.5 ml NE of Tasman Is , 43.208S, 148.229E ( AMS C.402693, 6) . 113 m, NE of Cape Pillar , 43.167S, 148.112E ( AMS C.402723, 1) . 399 m, off Cape Naturaliste , 40.843S, 148.775E ( AMS C.402628, 22; AMS C.402692, 2).

Literature records. Beachport, 150 fms. [= 274 m], 200 fms. [= 365 m], SA; Cape Jaffa, 100, 130, 300 fms. [= 182, 237, 548 m], SA; Cape Wiles, 100 fms. [= 182 m], SA ( Cotton, 1945).

Remarks. Cotton & Godfrey (1933) also cite Cape Pillar, Tasmania, 100 fms. [= 182 m] as a locality for this species. This could indicate paratypes, but the whereabouts of these specimens is currently unknown (SAM?).

The characteristic strong axial sculpture on the shoulder and the more numerous weaker axials on the base of T. gunteri is shared with A. s.l. finlayi ( Powell, 1937) from Three King Is, New Zealand. If these two species should be synonymous, T. gunteri has priority. Although some species have been considered to be shared between continental Australia and New Zealand [e.g. Incisura rosea (Hedley, 1904) with nominate subspecies in New Zealand and Australian subspecies remota (Iredale, 1924)] such indications are dubious and may simply reflect our poor knowledge of microgastropods in general. Anatoma aupouria occurs in Australian territorial waters, though the area belongs to the New Zealand faunal province.

Figures

FIGURE 15. Thieleella gunteri. AMS C.31845. 40 miles S of Cape Wiles, SA, Australia, 174­–183 m. Scale bar shell = 200 µm. Scale bar protoconch = 50 µm.

FIGURE 16. Thieleella gunteri. A–B. AMS C.402690. 40 miles south of Cape Wiles, SA, Australia. C. AMS C.402691. Off Cape Martin, SA, Australia. Scale bars shell = 200 µm. Scale bars protoconch and spire = 50 µm.

FIGURE 17. Thieleella gunteri. A. AMS C.402628. Off Cape Naturaliste, TAS, Australia. B–C. AMS C.402692. Off Cape Naturaliste, TAS, Australia. Scale bars shell = 200 µm. Scale bars protoconch and spire = 50 µm.

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