Australdonta florencei, Sartori, André F., Gargominy, Olivier & Fontaine, Benoît, 2013

Sartori, André F., Gargominy, Olivier & Fontaine, Benoît, 2013, Anthropogenic extinction of Pacific land snails: A case study of Rurutu, French Polynesia, with description of eight new species of endodontids (Pulmonata), Zootaxa 3640 (3), pp. 343-372 : 358-359

Australdonta florencei sp. nov.

Figures 3 D, 7, 14D, 15D

Examined material (1744 specimens). Holotype: MNHN 25203, Rr4. Paratypes: MNHN 25204, 8 shells, Rr38. Additional material: 58 shells, Rr19; 821 shells, Rr20; 11 shells, Rr21; 19 shells, Rr22; 1 shell, Rr30; 338 shells, Rr35; 14 shells, Rr36; 377 shells, Rr38; 5 shells, Rr40; 1 shell, Rr43; 23 shells, Rr52; 13 shells, Rr54; 54 shells, Rr66.

Diagnosis: Shell with a rounded periphery; teleoconch sculpture of spiral riblets and well-spaced axial ribs; palatal wall lacking barriers or displaying two to four traces.

Description: Shell depressed, white to light fawn; usually without markings, seldom with narrow, oblique or curved flammulations fading out towards the shell base. Shell thin, opaque to subpellucid; periostracum adherent, shiny. Apex flat to barely elevated; spire slightly to moderately raised, last whorl descending more rapidly. Apical and umbilical sutures impressed; whorls and periphery evenly rounded. Transition between protoconch and teleoconch indistinct. Protoconch ornamented by very fine, wobbly spiral lirae, forming a reticulated pattern with primary and secondary elements of axial sculpture. Primary axial sculpture present from the second whorl onwards, comprised of ribs that become coarser at the transitional zone between protoconch and teleoconch; primary ribs with interspaces four to eight times their width, persisting on the teleoconch. Secondary axial sculpture present from the nucleus approximately to the end of the second whorl, consisting of fine lirae that gradually transition into wavy riblets; secondary riblets with interspaces three to five times their width. Spiral sculpture of low to moderately prominent riblets, with interspaces two to four times their width, present from the third whorl onwards, occasionally forming minute nodules at intersections with axial ribs. Umbilicus wide, deep. Peristome crescent-shaped. Palatal wall usually with two or three barrier traces, rarely displaying four or lacking traces altogether; palatal traces similar in prominence, shallowly recessed, extending approximately one-sixteenth to one-eighth whorl, with gradual anterior and posterior descension; first and second basal in position; third infraperipheral, usually lacking. Parietal barriers usually three, less commonly two in number, not recessed within aperture, extending inwards a little less than one quarter whorl, with gradual anterior and posterior descension, gradually decreasing in prominence from the first to the third barrier; first and second barriers invariably present, third often lacking; first and third approximately constant in height throughout their extent; second higher posteriorly. Rarely with two traces between the second and third barriers. Other shell features that can be expressed numerically are shown in Table 2 .

Remarks: A. florencei is somewhat variable in spire elevation, even though the apex is always flat or only barely elevated. The vast majority of examined specimens were similar to the holotype in having a slightly raised spire ( Fig. 3 D), but some were found with a considerably higher spire ( Fig. 7 E). Individuals with the spire almost flat are rare and resemble A. sibleti in shape. They can be distinguished from that species by the narrower, deeper umbilicus and conspicuous spiral ornamentation that characterize A. florencei . These same criteria, together with presence of palatal traces instead of barriers, easily separate A. florencei from the somewhat similar A. pseudplanulata .

Etymology: This species is dedicated to Jacques Florence, eminent botanist and delightful field companion.

Figures

FIGURE 3. Holotypes of: A. Australdonta oheatora sp. nov.; B. A. anneae sp. nov.; C. A. sibleti sp. nov.; D. A. florencei sp. nov. Scale bars = 1 mm.

FIGURE 7. Australdonta florencei sp. nov. A – C. Holotype (MNHN 25203), apical views; A. General view; B. Sculpture of the protoconch and early teleoconch; C. Sculpture of the late teleoconch; D. Paratype 1 (MNHN 25204), detail of the peristome; E. Specimen from station Rr 38, displaying an unusually high spire. Scale bars: A, E = 1 mm; B – D = 200 µm.