Mautodontha (Mautodontha) daedalea (Gould, 1846)

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 : 9-12

Mautodontha (Mautodontha) daedalea (Gould, 1846)

Figures 3 D; 4; 5; 35A; 37A; 39.

Helix daedalea Gould 1846a , p. 173.

Helix daedalea Gould—Pfeiffer 1848 , p. 186.

Helix (Endodonta) daedalea Gould—Albers 1850 , p. 89.

Helix daedalea Gould—Gould 1852 , pp. 54–55.

Helix daedalea Gould—Gould 1860 , p. 4, pl. 4, figs 51,51a–d. Helix daedalea Gould—Pfeiffer 1853 , p. 144.

Pitys daedalea (Gould) — Adams & Adams 1858, p. 113.

Helix daedalea Gould—Pfeiffer 1859 , p. 155.

Helix (Endodonta) daedalea Gould—Albers 1860 , p. 90.

Helix daedalea Gould—Gould 1862 , pp. 21–22.

Helix daedalea Gould—Pfeiffer 1868 , p. 221.

Pitys daedalea (Gould) — Pease 1871, p. 474.

Helix daedalea Gould—Pfeiffer 1876 , p. 258.

Helix (Endodonta) daedalea Gould—Tryon 1887 , p. 64, pl. 12, figs 23–25. Endodonta (Thaumatodon) daedalea (Gould) — Pilsbry 1893, p. 27. Thaumatodon daedalea (Gould) — Cooke 1934, p. 5.

Endodonta consobrina (Garrett) —Aubert de la Rüe & Soyer 1958, p. 365, non Pitys consobrina Garrett 1884 . Helix daedalea Gould, 1846 — Johnson 1964, p. 65.

Mautodontha (Mautodontha) daedalea (Gould, 1846) — Solem 1976, pp. 157–158, table 65, figs 73c–d. Mautodontha daedalea (Gould, 1846) — Solem 1983, pp. 279–280.

Examined material (2780 specimens). MNHN, unregistered, 11 shells, Tuamotu Islands: Makatea, coll. E. Aubert de la Rüe 1955, det. Solem; 104 shells, Mk03; 425 shells, Mk04; 135 shells, Mk05; 10 shells, Mk06; 23 shells, Mk07; MNHN 25584, 29 specimens preserved in ethanol (21 with soft parts, 8 empty shells), Mk08; 1000 shells, Mk08; 372 shells, Mk09; 69 shells, Mk10; 2 shells, Mk11; 15 shells, Mk12; MNHN 25587, 1 shell (specimen 9), Mk13; MNHN 25588, 8 shells (specimens 10–17), Mk13; 221 shells, Mk13; 24 shells, Mk15; 28 shells, Mk16; 14 shells, Mk17; 13 shells, Mk18; 18 shells, Mk19; 31 shells, Mk20; 45 shells, Mk21; 141 shells, Mk22; 41 shells, Mk25.

Type locality. Matea Islands [= Makatea].

Diagnosis. Shell less than 4 mm in diameter, discoidal, flammulated, without a supraperipheral groove; teleoconch sculptured by narrow, tall and relatively crowded primary axial ribs (> 110 ribs on body whorl); palatal wall with 5–6 barriers, rarely accompanied by 1–3 traces; parietal wall with 3–4 barriers, rarely accompanied by 1– 2 traces.

Description. Shell discoidal, white to light brown, with maroon flammulations, regularly or irregularly spaced, often fading out in the vicinity of the umbilicus. Shell wall thin, opaque to pellucid; periostracum adherent, shiny. Apex flat to barely raised, spire barely elevated; last whorl descending more rapidly. Apical and umbilical sutures impressed; whorls slightly flattened above periphery or uniformly rounded; periphery rounded to obtusely angled. Transition between protoconch and teleoconch indistinct. Protoconch sculptured by fine axial riblets, initially with interspaces 10–15 times their width, undifferentiated; axial riblets progressively differentiating from the third quarter of the first whorl onwards, some increasing in prominence and transitioning into the primary ribs of the teleoconch, others becoming close-set and wavy, transitioning into the secondary riblets of the teleoconch. Spiral sculpture of the protoconch composed of approximately equidistant lirae with interspaces 4–6 times their width, persisting on the surface of the teleoconch. Primary axial sculpture of the teleoconch composed of narrow, tall ribs, with interspaces approximately 12–15 times their width, extended by deciduous periostracal lamellae. Secondary axial sculpture of the teleoconch composed of fine, crowded, wavy riblets, with interspaces approximately 3–5 times their width, extended by periostracal lamellae. Umbilicus shallow, V to U-shaped. Peristome crescentshaped; columellar lip very slightly reflected. Palatal wall usually with 5–6 barriers, all extending c. 1/8 whorl, slightly recessed within the aperture, descending gradually anteriorly and abruptly posteriorly; barrier 1 columellar in position, often absent or represented by a trace, often more deeply recessed than the others; barrier 2 at the junction of basal and columellar walls, intermediate in prominence between barrier 1 and barriers 3 to 5, similar in prominence to barrier 6; barriers 3 to 5 basal in position, approximately equidistant, similar in prominence; barrier 6 slightly supraperipheral. One to three additional traces rarely present on the palatal wall, variable in position, commonly occurring between barriers 2 and 3, or between barrier 6 and apical suture. Parietal wall usually with 3– 4 barriers, descending gradually anteriorly and abruptly posteriorly; barriers 1 to 3 extending c. 1/8 whorl, similar in prominence, equidistant, not recessed; barrier 4, when present, usually less prominent than the others, extending c. 1/8 whorl, not recessed; barrier 4 occasionally trace-like, extending c. 1/16 whorl, slightly recessed within aperture. One or two additional traces rarely present on the parietal wall, variable in position, commonly occurring between barriers 2 and 3, or between barrier 3 and umbilical suture. Other shell features that can be expressed numerically are shown in Table 2 .

Remarks. The deciduous periostracal lamellae projecting from the axial sculpture of the teleoconch were only visible in the few fresh shells and live specimens recovered from station Mk08. These specimens represent the only extant endodontid population found on Makatea in 2005. Based on material deposited in the Bishop Museum, Solem (1976, p. 158) established that M. (M.) daedalea also occurred in the atolls of Anaa and Niau, Tuamotu Archipelago. The presence of the species in Tahiti, Society Islands, was reported by Gould (1852, p. 55) but subsequently challenged by Cooke (1934, p. 5).

M. (M.) daedalea appears to be rather variable, particularly in the diameter and configuration of its umbilicus, number of apertural barriers, and in the shape of its periphery. The lectotype designated by Solem (1976) and most specimens we collected have V-shaped, widely open umbilici ( Fig. 4 A–B; Table 2 , specimens 1–8), but numerous shells display U-shaped umbilici ( Fig. 4 C–D) that vary in diameter from very wide ( Fig. 4 C; Table 2 , specimens 9– 17) to comparatively narrow ( Fig. 4 D; Table 2 , specimens 18–26). Variation in the number of apertural barriers appears to be loosely correlated with differences in the shape of the periphery; specimens with a more angular periphery ( Fig. 4 B) usually have fewer barriers than those with the periphery uniformly rounded ( Fig. 4 C–D), but numerous exceptions were found among the studied material.

Although isolated specimens may appear distinct, intermediates bridging the gap between morphological extremes were numerous, and ultrastructural examination failed to reveal noteworthy differences in sculpture and protoconch morphology among the three umbilical forms. We therefore interpret the observed variability as intraspecific.

Figures

FIGURE 4. Mautodontha (Mautodontha) daedalea. A. Lectotype (MCZ 169115); B. Specimen 1 (station Mk 13); C. Specimen 9 (MNHN 25587, station Mk 13); D. Specimen 18 (station Mk 22); Scale bar = 2 mm.

FIGURE 3. A – C. Photographs of Mautodontha (Garrettoconcha) spelunca sp. nov. (MNHN 25583, paratype 3), showing the placement of measurements used in this study; D. Peristome of Mautodontha (Mautodontha) daedalea (MNHN 25587, specimen 9), showing the numbering scheme for apertural barriers used in this study. Abbreviations: ah, aperture height; aw, aperture width; d, shell diameter; h, shell height; nr, number of ribs on body whorl (counted from this line to the aperture); nw, number of whorls (line marks the boundary between whorls); sp, spire protrusion; t 1, t 2, barrier traces; u, umbilicus diameter. Scale bars: A – C = 2 mm; D = 0.5 mm.