Pseudolibera cookei, 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 : 47-48

Pseudolibera cookei sp. nov.

Figures 25 C; 28; 36G; 38D; 39.

Examined material (9 specimens). Holotype: MNHN 25675, Mk13. Paratypes: MNHN 25676, 8 shells, Mk13. Type locality. West coast of Makatea, approximately 3 km south of Temao (15.85189°S; 148.28018°W). Cave. Limestone, alt. 10 m; station Mk13.

Diagnosis. Shell less than 7 mm in diameter, depressed, tinted; apex and spire elevated; peripheral keel slightly angled towards the shell base; teleoconch sculptured by coarse, relatively well-spaced primary axial ribs (<100 ribs on body whorl) and low spiral riblets, the former much reduced and the latter absent on shell base; palatal wall devoid of barriers; 1 parietal barrier extending 3/4 whorl, not bifurcated.

Description. Shell depressed, dome-shaped, white, with an amber tint covering most of the surface, absent from the vicinity of the umbilicus. Shell wall thin, opaque to subpellucid; periostracum adherent, shiny. Apex and spire elevated, latter whorls descending slightly more rapidly. Apical suture adpressed at apex, progressively deepening in subsequent whorls; umbilical suture impressed at apex, adpressed approximately from the third whorl onwards. Peripheral keel slightly angled towards the shell base; whorls concave above and below peripheral keel, transitioning into broadly convex toward the apical suture and shell base; junction of basal and columellar walls initially obtusely angled, developing a keel approximately from the fourth whorl onwards. Transition between protoconch and teleoconch indistinct. Primary axial sculpture of the protoconch composed of relatively broad ribs, with interspaces c. 3 times their width; 4–6 secondary axial riblets, each c. 1/5 the width of the primary ribs and wavy in morphology, occupying the interspaces between primary ribs. Primary ribs of the protoconch gradually transitioning into taller ribs, which comprise the primary axial sculpture of the teleoconch; secondary riblets of the protoconch gradually increasing in number and persisting as the secondary axial sculpture of the teleoconch. Spiral sculpture developing approximately from the third whorl onwards, composed of very low, broad riblets, with interspaces similar to their width, forming nodules at intersections with the axial sculpture. Spiral sculpture absent and axial sculpture much reduced on shell base. Umbilicus rapidly expanding in diameter for approximately the first 3 whorls, remaining constant in diameter for approximately 1 whorl, subsequently constricted by inward growth of the lower columellar wall and lip. Peristome elongated crescent, with rostrate periphery; columellar lip reflected. Palatal wall devoid of barriers. Parietal wall with 1 barrier, extending c. 3/4 whorl, positioned slightly closer to the apical than the umbilical suture, descending gradually anteriorly and posteriorly. Other shell features that can be expressed numerically are shown in Table 3.

Remarks. The prominent and well-spaced axial sculpture of P. cookei confers a pleated aspect to its shell periphery and, together with the absence of spiral sculpture on the shell base, are the best features to distinguish this species from similarly shaped Pseudolibera species, namely P. lillianae , P. solemi and P. matthieui .

Etymology. This species is dedicated to Charles Montague Cooke, Jr., pioneer of the study of the malacofauna of Makatea.

Figures

FIGURE 25. Holotypes of: A. Pseudolibera solemi sp. nov.; B. P. matthieui sp. nov.; C. P. cookei sp. nov.; D. P. aubertdelaruei sp. nov. Scale bars = 5 mm.