Pseudolibera lillianae Solem, 1976

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 : 39-41

Pseudolibera lillianae Solem, 1976

Figures 23 ; 24; 36A; 37F; 39.

Libera sp. Cooke 1934, pp. 5–6.

Endodonta obolus (Gould) —Aubert de la Rüe & Soyer 1958, p. 365, non Helix obolus Gould 1846b . Trochonanina obconica (Pease) [in part]—Aubert de la Rüe & Soyer 1958, p. 365, non Helix obconica Pease 1865 . Pseudolibera lillianae Solem 1976 , pp. 384–385, figs 168a–b.

Examined material (1140 specimens). Holotype: BPBM 115805, Tuamotu Islands: Makatea, 1 mile inland at 250 ft. elevation. Collected on a hillside around roots of a plant by Mrs. G.P. Wilder on October 24, 1932. Additional material: MNHN, unregistered, 13 shells, one of which gold coated, det. A. Solem [presumably collected by E. Aubert de la Rüe in 1955 in Makatea; see remarks below]; MNHN 25589, 18 shells, Mk04; 4 shells, Mk09; 14 shells, Mk10; 361 shells, Mk12; 362 shells, Mk13; 226 shells, Mk16; 133 shells, Mk19; 6 shells, Mk20; 2 shells, Mk25.

Type locality. Tuamotu Islands: Makatea, 1 mile inland at 250 ft. elevation.

Diagnosis. Shell less than 9 mm in diameter, depressed, flammulated; apex and spire elevated; peripheral keel long and narrow; teleoconch sculptured by subequal axial and spiral ribs, reduced on shell base; palatal wall devoid of barriers; 1 parietal barrier extending 1/2 to 1 whorl, not bifurcated.

Description. Shell depressed, dome-shaped, white, with regularly spaced, amber flammulations, frequently interrupted at the shell periphery and vicinity of the umbilicus; flammulations on the shell base larger and fewer, commonly absent on the last half whorl; shell base rarely tinted with an amber background coloration, in addition to flammulations. Shell wall thin, opaque to subpellucid; periostracum adherent, shiny. Apex and spire elevated, later whorls descending slightly more rapidly. Apical suture adpressed at apex, progressively deepening in subsequent whorls; umbilical suture adpressed. Whorls concave above and below long, narrow 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 fifth 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 occupying the interspaces between primary ribs, each approximately 1/5 the width of the primary ribs and wavy in morphology. Primary ribs of the protoconch gradually transitioning into narrower and less conspicuous ribs, which comprise the primary axial sculpture of the teleoconch; secondary riblets of the protoconch persisting as the secondary axial sculpture of the teleoconch. Spiral sculpture developing approximately from the beginning of the third whorl onwards, composed of wavy ribs, similar in prominence and spacing to the primary axial ribs of the teleoconch; nodular projections present at intersections between spiral and axial ribs. Sculpture less prominent on shell base than above periphery. Umbilicus rapidly expanding in diameter for approximately the first 3 whorls, remaining constant in diameter or expanding slightly from approximately the third to the fifth 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 1/2 to 1 whorl, positioned slightly closer to the apical than the umbilical suture, descending gradually anteriorly and posteriorly, rarely flanked by 1 trace on each side. Parietal traces, when present, extending c. 1/4 whorl. Other shell features that can be expressed numerically are shown in Table 3.

Remarks. Solem (1976, pp. 5, 384) found a preliminary description of this species among Montague Cooke’s unpublished notes and, wishing to recognize Cooke’s contribution, attributed authorship of P. lillianae to “Cooke & Solem”. However, Solem (1976, p. 5) clearly stated that all diagnoses and descriptions published in his monograph were prepared by himself. Hence, Solem was alone responsible for satisfying the criteria of availability and, following ICZN Article 50 ( ICZN 1999), is the sole author of P. lillianae .

Solem (1976) established P. lillianae based on only two specimens—the considerably worn holotype ( Fig. 23 A) and a very small juvenile specimen collected by Aubert de la Rüe & Soyer (1958) and misidentified as Endodonta obolus . Solem (1983, pp. 279–280) noted that, during a visit to the MNHN, he found several additional specimens of this species mixed in a lot that Aubert de la Rüe & Soyer (1958) had reported as Trochonanina obconica , which also contained three new species of the genus. Solem’s premature death prevented him from establishing those three new species; they are described herein as P. solemi sp. nov., P. aubertdelaruei sp. nov. and P. extincta sp. nov. As for the specimens of P. lillianae collected by Aubert de la Rüe & Soyer (1958) and recognized by Solem (1983), it seems clear that they are contained in the first lot we list in our examined material, even though the lot now lacks labels detailing its history and collection data. The lot contained 14 specimens, but one of them proved to be P. solemi sp. nov.

P. lillianae was the most abundant Pseudolibera in the material recovered in 2005 ( Fig. 39 ). A few wellpreserved specimens were found, which reveal the color pattern of the species ( Fig. 23 B) and details of its sculpture ( Fig. 24 A–C). Only one specimen among the hundreds recovered displayed parietal traces in addition to the single barrier ( Fig. 24 D). P. lillianae is the largest Pseudolibera in shell diameter and the only species of the genus with a long and narrow peripheral keel that is frequently chipped off.

Figures

FIGURE 23. Pseudolibera lillianae. A. Holotype (BPBM 115805); B. Specimen 1 (MNHN 25589); Scale bars = 5 mm.

FIGURE 24. Pseudolibera lillianae. A – C. Specimen 1 (MNHN 25589), apical views; A. General view; B. Sculpture of the protoconch and early teleoconch; C. Sculpture of the late teleoconch; D. Specimen 9 (station Mk 16), umbilical view, showing parietal traces flanking the barrier; Scale bars: A, D = 2 mm; B, C = 0.4 mm.

FIGURE 39. Diagrammatic representation of the abundance per station and per species of the endodontid specimens collected in Makatea. The thickness of the bars along the axes and the area of the circles in the grid is proportional to the number of collected specimens.