Mautodontha (Garrettoconcha) makateaensis, Sartori, André F., Gargominy, Olivier & Fontaine, Benoît, 2014

Sartori, André F., Gargominy, Olivier & Fontaine, Benoît, 2014, Radiation and decline of endodontid land snails in Makatea, French Polynesia, Zootaxa 3772 (1), pp. 1-68 : 22-24

Mautodontha (Garrettoconcha) makateaensis sp. nov.

Figures 14 A; 15; 35J; 38B; 39.

Examined material (19 specimens). Holotype: MNHN 25683, Mk12. Paratypes: MNHN 25684, 8 shells, Mk12. Additional material: 10 shells, Mk12.

Type locality. Approximately 1 km north of Temao port, Makatea (15.81638°S; 148.27639°W). Large fault in the cliff, shaded. Ferns. Limestone, alt. 10 m; station Mk12.

Diagnosis. Shell less than 4 mm in diameter, subdepressed, without flammulations; teleoconch sculptured by narrow, tall, relatively well-spaced primary axial ribs (<90 ribs on body whorl); umbilicus V-shaped; palatal wall with 3 barriers; parietal wall with 2 barriers, rarely accompanied by 2 traces.

Description. Shell subdepressed, white, without flammulations. Shell wall thin, opaque to pellucid; periostracum adherent, shiny. Apex and spire strongly elevated; later whorls descending slightly more rapidly. Apical and umbilical sutures impressed; whorls and periphery uniformly rounded; basal and columellar walls transitioning smoothly. Transition between protoconch and teleoconch indistinct. Axial sculpture of the protoconch initially composed of pairs of fine riblets separated by interspaces 10–15 times the width of an individual riblet; riblets within each pair initially separated by a narrow interspace 1–2 times their width, subsequently coming closer and progressively merging into prominent ribs, which comprise the primary sculpture of the teleoconch. Single axial riblets between pairs occurring approximately from the second half of the first whorl, progressively increasing in number and transitioning into the secondary sculpture of the teleoconch. Spiral sculpture of the protoconch composed of lirae with interspaces 3–6 times their width, fading out approximately on the second half of the second whorl. Teleoconch sculptured by tall, narrow, prominent axial ribs, with interspaces 4–5 times their width, overlaid by a secondary ornament of crowded axial riblets, with interspaces c. 3–4 times their width.

Teleoconch devoid of spiral sculpture approximately from the third whorl onwards. Umbilicus very deep, Vshaped. Peristome subovate; columellar lip slightly reflected. Palatal wall with 3 barriers, all basal in position, extending c. 1/8 whorl, descending gradually anteriorly, similar in prominence, approximately equidistant, slightly recessed within the aperture; barriers 1 and 2 descending gradually posteriorly; barrier 3 descending abruptly posteriorly. Parietal wall with 2 barriers, both extending c. 3/16 whorl, descending gradually anteriorly and posteriorly, similar in prominence, taller than palatal barriers, not recessed within the aperture. Rarely with 1 trace between parietal barriers and 1 trace between parietal barrier 2 and umbilical suture. Other shell features that can be expressed numerically are shown in Table 2 .

Remarks. Little intraspecific variation is observable in our sample of this species, all specimens being very similar to the holotype. The pattern of two parietal and three palatal barriers, together with a larger shell at the same whorl count, are the easiest criteria for distinguishing this species from M. (G.) temaoensis . Only M. (G.) passosi sp. nov. and M. (G.) spelunca sp. nov. are also characterized by two parietal barriers; both may be distinguished from M. (G.) makateaensis by their more closely-set sculpture.

Etymology. From Makatea.

Figures

FIGURE 14. Holotypes of: A. Mautodontha (Garrettoconcha) makateaensis sp. nov.; B. M. (G.) passosi sp. nov.; C. M. (G.) spelunca sp. nov. Scale bars = 2 mm.