Corresponding author: John Slapcinsky (
Academic editor: M. Schilthuizen
We describe a new stylommatophoran land snail of the family
Slapcinsky J, Kraus F (2016) Revision of Partulidae (Gastropoda, Stylommatophora) of Palau, with description of a new genus for an unusual ground-dwelling species. ZooKeys 614: 27–49. doi:
The land-snail fauna of oceanic islands in the Pacific is disharmonic, with about 20 of the nearly 130 terrestrial snail families represented. Except for camaenid and bradybaenid species near the Asian and Australian continental margins (
More than 50% of all extinctions documented since 1500 are mollusks; nearly 40% of these are terrestrial snails from oceanic islands (
Palau harbors an estimated 200 species of land snails, of which only 78 have been described (
During a visit in 1998, one of us (
We hand-collected specimens, drowned them overnight, and preserved them in 75% ethanol. We dissected pallial organs, genitalia, and buccal masses from specimens under 75% ethanol using a dissecting microscope, and we isolated radulae from buccal masses using a 3% sodium hypochlorite solution. We imaged radulae and jaws using a Field Emission-SEM, photographed genital anatomy, and drew pallial organs with the aid of a drawing tube. We used Helcion Focus software for photo stacking. We counted whorls from the suture of the first whorl to the body whorl (Fig. Fred Kraus collection
Shell measurements:
We isolated genomic DNA from 1 cubic mm of foot tissue of the new taxon using a solution of 10% Chelex beads (Bio-Rad Laboratories) in sterile water heated to 65 °C for 4 hours. DNAses and other protein contaminants were digested using Proteinase K. We amplified a 655-bp nucleotide fragment of cytochrome oxidase I
The familial placement of this new, unusual stylommatophoran species is not immediately obvious based on shell characters. The shell resembles some
Pallial organs of = mantle collar = nephridium = pericardium = pulmonary vein = renal pore
= apical chamber = albumen gland = bursa copulatrix = hermaphroditic duct = free oviduct = penis = prostate gland = penial pilasters = penial retractor muscle = vas deferens
The penis in
Known only from Palau.
Shell large, elongate, with a tall, relatively flat-sided and acutely pointed spire (Fig.
Shells of
Apical sculpture of partulid genera:
Schematic summary of penial anatomy of partulid genera, from = apical chamber = epiphallus = flagellum = penial pilasters = penial retractor muscle = vas deferens
This genus is isolated to the west of all previously named partulid genera (Fig.
Geographic ranges of the five partulid genera. Map modified from
An unrooted network of partial
One species,
Shell obese-pupoid (Fig.
The shells of
A comparison of a partial
Known only from Palau.
Palau: Eil Malk (Mecherchar) Island: southeastern peninsula, from hermit crab, F. G. Thompson, 22 October 1985 (
Large, obese-pupoid shell approximately 18–23 mm in height and 13–15 mm in width, with 4.5–5.1 whorls. Body whorl descends below the penultimate whorl. Protoconch sculptured with growth lines, strongest near the sutures; spiral sculpture lacking or, less commonly, comprising faint and irregular striae. Wavy spiral striae are progressively stronger and more regular on penultimate and body whorls but never become regular and strong. Peristome widely expanded and reflexed, palatal and parietal margins nearly parallel, base evenly rounded. Palatal margin with slight central thickening; parietal margin attaching to the body whorl at umbilicus. Penis long, with apical insertion of the vas deferens and retractor muscle. Approximately ten longitudinal pilasters coalesce to form a ridge that defines a small apical chamber below the insertion of the vas deferens.
Shell obese-pupoid, height 22.2 mm, width 14.0 mm, with 4.9 whorls (Fig.
The new species differs from other partulids as stated for the genus.
The trivial name is a feminine Latin adjective meaning unusual, in recognition of both the unusual shell shape and ecological habits for a partulid.
Known only from southeasternmost Ngeruktabel (Uruktapel) and nearby Mecherchar (Eil Malk) Islands, Palau, Caroline Islands (Figs
Live individuals of the new species were collected only from beneath rocks, between soil and the overlying rock, or deep in rock piles. Dead shells were also found on the soil surface and in leaf litter among stones. The site is well-developed limestone rainforest (Fig.
Photos of forested habitat at the type locality of
Palau comprises more than 700 small islands at the western end of the Pacific Ocean, totaling 490 km2 of land and extending over 700 km, although the majority of islands lie within a single fringing reef approximately 130 km in length. These islands are situated some 800 km east of the Philippines and 850 km north of New Guinea and form the westernmost component of the Caroline Islands. They lie along the southern end of the Kyushu-Palau Ridge, a relict intra-oceanic volcanic-arc system the evolution of which ended 15–25 MYA (
All known partulids, like many other Central Pacific taxa, including
We thank Ron Crombie for providing GPS coordinates along the trail to the German lighthouse and for information on the type locality and Palau in general; Ron Leidich for kindly providing habitat photos; Don Cameron for advice on Greek etymological options; Taehwan Lee and Diarmaid O'Foighil for a copy of Yoshio Kondo’s thesis and information from their