Corresponding authors: Chirasak Sutcharit (
Academic editor: Thierry Backeljau
Thailand is located at the crossroads of several biogeographical regions, and boasts a high level of biodiversity, especially among the malacofauna. The most recent checklist of land snail species in Thailand was compiled more than twenty years ago, and so this checklist needs revision and the addition of newly discovered taxa. This study updates the taxonomy and species list of the operculated land snail family
This annotated checklist contains 30 nominal species and two subspecies from seven genera currently known to occur in Thailand. We describe two species of
Thailand boasts a high diversity of both flora and fauna, as the country is located within the Indo-Burma biodiversity hotspot, which is deemed the “crossroads” of three biogeographical regions: southern China in the north, the Indian subcontinent and the Himalayas in the west, and Sundaland in the south (
Although the terrestrial malacofauna exhibits a particularly high diversity, studies on species diversity in Thailand have only been sporadically published in the past (
Thereafter, and until the twentieth century, studies on Thai land snails were fragmentary and occasionally done by western malacologists who obtained specimens from merchants, naturalists and missionaries visiting Thailand. For example, Otto F. von Möllendorff studied land snails and described new species based on Carl Roebelen’s collections from the Samui Islands and based on Hans Fruhstorfer’s collections from several localities (
More recently, land snail research in Thailand was boosted after SP began studying Thai land malacofauna in the 1990s (
The family
Recently, the taxonomy of some genera has been reviewed; i.e.,
This study is the first comprehensive work to update the taxonomy and species list of operculated land snails in the family
The data compiled in this checklist are from two main sources. The first source is the published malacological literature ranging from the nineteenth century until the present (February 2022). These historical works, i.e., the “Proceedings of the Zoological Society of London”, are available online at
The direct searching for snails involved all potential land snail microhabitats that could be accessed, such as deep litter beds, decaying tree trunks, rock surfaces and crevices and, especially, limestone cliffs and caves. All sampled locations were recorded. At each locality, land snails were searched for intensively for ca. 1–2 h by three or four well-trained assistants. All living snails were photographed and killed by the two-step method for euthanasia (
Sampling localities of the
Habitat and vegetation around
Species identification of specimens is based on the literature and comparisons with the type specimens and/or reference collections from several natural history museums. The classification of the higher taxa in the list is according to
The terminology of teeth follows those of pupillid snails in
General shell morphology of
Photographs of the type specimens from the Molluscs Collection (IM) of
All the nominal species and subspecies names described as new to science in this work are attributed to the first author (Jirapatrasilp). Thus, a complete citation of the authors is “Jirapatrasilp in Jirapatrasilp et al., 2022”
A total of 195 voucher specimen lots was collected over the entire survey period and represented in this study. In total, 30 nominal species with two subspecies from seven genera are currently known to occur in Thailand. Two species of
List of species of the family
Subfamily | Genus (and species group) | Species with recently collected material | Species not recently collected but based on literature and museum collections | Species with uncertain record from Thailand, based on literature only |
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Total | 7 | 25 | 3 | 4 |
Currently, there are three subfamilies within the family
The subfamily
There are a total of six genera with 12 species and one subspecies of pupinellinid known to occur in Thailand, and two additional species have uncertain records.
Shell high conical to elongate ovate. Sculpture mostly smooth, rarely ribbed. Periumbilical keel either present or absent. Aperture round without any tubes or apparent slits, sometimes with a slight angular indentation at peristome upper junction. Operculum thin, flat, closely coiled.
Shell size and matt surface of
For the resurrection of
Shell elongate conical without any periumbilical keel. Aperture round with a slight angular indentation at upper junction of peristome.
Myanmar and western Thailand (
As the original description did not explicitly state that the description of this species was based on a single specimen (nor could this be inferred), the designation of a holotype by
Shell elongate conical without any periumbilical keel. Apertural round without any indentation.
Peninsular Malaysia, Sumatra Island, and southern Thailand (
No material of this species was found during this survey. Although
The name “
Shell of great size (up to 50 mm in shell height); pupoid shape with shallow posterior angled groove at palatal edge as breathing device; with or without parietal declining shoulder inside the peristome.
The taxonomic history of
Shell height 35–40 mm. Last whorl and penultimate whorl purple to black; spire and apex distinct yellow to bright orange. Dorsal side of last whorl with bold wrinkles. Aperture round, without apertural groove; apertural lip expanded, bright orange to red. Umbilicus subumbilicate.
Phetchabun Range in central and northeastern Thailand, and probably in both Cambodia and Laos (
One differential diagnostic character of
Shell height < 35 mm. Shell entirely black to purple. Dorsal side of last whorl with bold wrinkles. Aperture almost round, shallow posterior angled groove present; apertural lip expanded, yellow to pale orange. Umbilicus narrow.
This subspecies is different from the nominotypical subspecies by a smaller shell size, an entirely black to purple shell, and a distinct karyotype pattern of (7m+3sm+2st+1t) (
Loei and Nong Bua Lam Phu provinces, northeastern Thailand (
DNA data are required to demonstrate whether
Shell height > 40 mm. Shell elongated, reddish brown to bright orange or red. Dorsal side of last whorl with very fine wrinkles. Aperture round, without apertural groove; apertural lip expanded, yellow to pale orange. Umbilicus narrow.
Laos and an uncertain record from northern Thailand (
No material of this species was found during this survey, and the record in Thailand needs further confirmation. The type material of this species was presumably lost (
Shell turriform or spindle-shaped, rather regularly ribbed, without additional groove above the suture, and without basal keel. Aperture rather round with slight columellar-parietal and more angled parietal-palatal transitions.
The taxonomic history of
Shell slender turriform; ca. 9 whorls, with regular strong ribs. Area between ribs with very fine spiral striation mostly on upper whorls. Peristome reflected.
Mae Hong Son Province and Kayah State, Myanmar (
Although the apex of the
Doi Ang Khang, Fang District, Chiang Mai Province, Thailand,
Shell ovate to ovate conical, widest at penultimate whorl; ca. 7½ whorls, with regular weak ribs. Area between ribs with very fine radial striation. Outer peristome expanded and reflected.
Shell height 8.8–9.2 mm; shell width 4.4–4.6 mm. Shell ovate to ovate conical, widest at penultimate whorl, solid, semi-transparent, pale orange. Whorls ca. 7½ with sutures deep. Protoconch ca. 2 whorls (slightly eroded), first ca. 1½ whorl very finely granulated; remaining whorls and teleoconch very finely, regularly ribbed every 0.2 mm; ribs weak and 0.1 mm wide. Area between ribs with very fine radial lines, visible only under high magnification (> 20×), getting weaker in earlier whorls. Last whorl with 28–30 ribs. Apex obtuse. Spire angle ca. 50°. Aperture rounded with very slightly angled columellar-parietal transition and more sharply angled parietal-palatal transition; outer peristome expanded and reflected (0.4–0.5 mm wide and 0.3 mm thick), white to pale pinkish in colour. Umbilicus closed. Operculum unknown.
The specific epithet is named after Doi Ang Khang, the type locality of this species.
Known only from the type locality.
This species exhibits infraspecific variation in shell shape from ovate to ovate conical (Fig.
Pha Daeng Cave, Mueang Mae Hong Son District, Mae Hong Son Province, Thailand,
Shell elongate turriform; ca. 11 whorls, with regular strong ribs separated by wide space. Area between ribs with very fine spiral striation. Outer peristome expanded and strongly reflected.
Shell height 14.0–14.6 mm; shell width 4.8–5.1 mm. Shell elongate turriform, widest at its base, solid, semi-transparent, whitish to pale pinkish. Whorls ca. 11 with sutures deep. Protoconch ca. 2 whorls (slightly eroded), first ca. 1½ whorl very finely granulated; remaining whorls and teleoconch very finely, regularly ribbed every 0.4–0.5 mm; ribs strong 0.1 mm wide, triangular in cross section. Area between ribs with very fine spiral lines, visible only under high magnification (> 20×). Last whorl with 20–26 ribs. Apex obtuse. Spire angle ca. 30°. Aperture rounded with very slightly angled columellar-parietal transition and more sharply angled parietal-palatal transition appearing as indentation; outer peristome expanded and strongly reflected (0.5–0.6 mm wide and 0.5 mm thick), white to pale pinkish in colour. Umbilicus closed. Operculum unknown.
The specific epithet is dedicated to B. Páll-Gergely, a Hungarian malacologist who extensively studies the taxonomy and systematics of Southeast Asian land snails, especially revising the taxonomy of the genus
Known only from the type locality.
Shell with funnel- or gutter-like [= umbilical passage in
The most comprehensive compilation of members of this genus could be traced back to
Shell fusiform; last whorl ca. 60% of shell height. Apertural lip highly expanded and reflected; inner peristome thickened and cord-like; apertural lip when observed from lateral view almost straight. Parietal callus thickened and cord-like. Parietal tooth fin-shaped, highly thickened, covering posterior canal. Anterior canal funnel-like. Umbilicus closed.
Northern Vietnam (
Upon examining the type specimens of
Shell elongate fusiform; last whorl ca. 55–60% of shell height. Apertural lip expanded and slightly reflected; apertural lip when observed from lateral view almost straight. Parietal callus absent. Parietal tooth pointily sharp, located next to wide posterior canal. Anterior canal funnel-like. Umbilicus closed.
Northern Vietnam (
This taxon is allocated to the genus
Upon examining the type specimens of both
Shell ovate-fusiform; last whorl ca. 60% of shell height. Apertural lip slightly expanded and reflected, thickened cord-like peristome absent; apertural lip when observed from lateral view almost straight. Parietal callus somewhat distinct and cord-like. Parietal tooth sharp with wide base, thickened and covering posterior canal. Anterior canal funnel-like, appearing as a slit on the inside, widened on outer margin, bordered by a thickened columellar margin. Umbilicus closed.
Muong La District, Thuan Chau District, and Van Ho District, Son La Province, Vietnam (
This taxon is allocated to the genus
Shell ovate-fusiform; last whorl ca. two-thirds of shell height. Apertural lip expanded and slightly reflected; apertural lip curved when observed from lateral view. Parietal callus somewhat thickened and cord-like. Parietal tooth thickened, fin-shaped, covering posterior canal. Anterior canal forming a long gutter, extending into a spike-like protrusion. Umbilicus open and deep.
Known only from the type locality (
This taxon is allocated to the genus
Shell pupoid, with large penultimate whorl dominating the shell, being almost as wide as upper whorls combined when observed from apertural view. Peristome continuous, with parietal callus well-developed. Aperture shifting to the right side of the shell. Inner tube or breathing device short (of c. 0.25 whorl). Outer tube not perforated and varies in direction, never running strictly along the suture.
Shell ovate; body whorls bulging. Tube cylindrical, pointing upward and forward.
Malaysia and southern Thailand (
It is possible that
Shell elongate ovate; body whorls slightly bulging. Tube cylindrical, pointing diagonally downward and backward.
Northern Peninsular Malaysia and southern Thailand (
No material of this species was found during this survey.
Shell ovate; body whorls not bulging. Tube cylindrical and pointing straight upward.
Southern Thailand (
No material of this species was found during this survey.
Shell elongated ovate; body whorls slightly bulging. Tube thick and flat, turning first straight upward then abruptly downward, highly widening and extending to nearly the entire last whorl height.
Northern Vietnam (
The tube of one specimen from Tham Luang, Mae Sai District, Chiang Rai Province when turning downward does not adhere to the apertural margin (Fig.
Shell ovate; body whorls slightly bulging. Tube cylindrical, pointing upward and backward.
Northeastern India, Myanmar, and an uncertain record from Thailand (
No material of this species was found during this survey, and the record in Thailand needs further confirmation. The type locality on the label of the possible type specimen is “Siam”, which is different from that reported in the original description as “Arva”. A lack of a tube in a possible syntype
Shell elongated ovate. Periumbilical keel present. Aperture almost round; basal edge of peristome with a canal or indentation extending below into periumbilical keel. Operculum moderately thick to thick, corneous, circular, flat or cylindrical, closely coiled, multi-layer.
This genus comprises two subgenera: the nominotypical subgenus and
Shell rounded, spindle-shaped, translucent whitish to brown. Whorls 7, convex; third to penultimate whorls broader; last whorl narrower, detached, brought forward, with a filiform basal keel broader at the mouth. Aperture almost circular, always with basal indentation; palatal indentation obvious in specimens with thicker shell. Operculum thick cylindrical, corneous, multi-layer, spring-like when extended by force; inner operculum (attached to dorsal side of posterior body) translucent yellow, convex with crater within and conical protrusion in the middle; outer operculum (free surface) dark brown and usually eroded.
Northern Peninsular Malaysia and southern Thailand. The type locality of this species is still controversial while the occurrences in India and Nicobar Islands need further confirmation (
The name
Map of southern Thailand showing the distribution of
Map of northern Thailand showing the distribution of
Live specimens of
Umbilical, columellar and parietal views of
Shells of
Infraspecific variation of shell shape and colour found in the same collecting locality of
Only one genus,
Shell elongate ovate, smooth, with a shining enamel-like coating. Peristome with two canals; posterior canal at the suture; anterior canal oblique at the middle of columellar margin. Parietal callus normally thickened, and bordered by two teeth; parietal tooth located near or covering posterior canal; lower columellar tooth located near or covering anterior canal (Figs
Various diagnoses between
Diagnoses of the subgenera
Author and citation | ||
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P.M. Heude (Heu |
– | … interrupted peristome; columella cloven, right margin intact, parietal callus with tooth and slit. |
… The aperture is rather that of |
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(as of |
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W. Kobelt ( |
Canal simple, formed by a tongue-like projecting callus on the apertural wall. | Upper canal formed by a tongue detached from the callus and the edge of the mouth. |
W.J. Clench ( |
Possessing a well-developed parietal tooth within margin of aperture; possessing a columellar notch cut parallel with face of aperture. | Possessing a well-developed parietal tooth extending outward and up onto body whorls; possessing a columellar notch. |
The single character upon which the genus is based is only the extension of the parietal tooth outward and upward as a tongue-like process on the body whorl in |
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R. Egorov ( |
Parietal canal simple, formed by tongue-shaped projecting callus, sometimes reduced. Parietal tooth differently developed. | Parietal canal formed by apertural margin and tongue-shaped projected in front process separated from callus. |
Based on the distinction of shell teeth, canals (Figs
Figs
This species group is characterised by a triangular or fin-shaped parietal tooth covering a posterior canal. A columellar tooth is less thickened, never ear-shaped and mostly fin-shaped, located next to or covering an anterior canal. When observed from apertural view, the anterior canal mostly appears slit-like and the posterior canal is not visible. An apertural lip is straight or slightly curved when observed from lateral view. An operculum is round, thin, multispiral, yellowish, transparent corneous, and with a smooth edge.
The
This species group from mainland Southeast Asia contains seven species, including three nominal species and one new species (
Specimen of
External shell morphology of three mainland Southeast Asian
Shell ovate; last whorl ca. three quarters of shell height. Apertural lip slightly thickened, not expanded. Both parietal and columellar teeth fin-shaped and slightly thickened; parietal tooth covering posterior canal; columellar tooth next to slit-like anterior canal.
Peninsular Malaysia, Myanmar (
The type specimen of
The specimen of
All specimens from Thailand with a slightly thickened, fin-shaped parietal tooth covering the posterior canal are herein identified as
Shell ovate; last whorl ca. three quarters of shell height. Apertural lip slightly thickened, not expanded; basal position widened. Both parietal and columellar teeth fin-shaped and slightly thickened; parietal tooth covering posterior canal; columellar tooth next to slit-like anterior canal.
The type locality (
Shell ovate; last whorl ca. 60% of shell height. Apertural lip highly thickened, not expanded. Both parietal and columellar teeth fin-shaped and very thickened; parietal tooth always covering posterior canal; columellar tooth either next to or covering slit-like anterior canal.
Eastern Myanmar, Laos (
The specimen of
As this species is highly similar to
Khao Wong Cave, Ban Rai District, Uthai Thani Province, Thailand,
Shell ovate; last whorl ca. two thirds of shell height. Apertural lip thickened, not expanded to slightly expanded; with a furrow between inner and outer peristomes; inner peristome thickened and cord-like. Parietal tooth thickened, long trapezoid shaped, reaching beyond the middle of last whorl, outer border nearly straight, always covering posterior canal; columellar tooth thickened, curvedly triangular shaped, located next to slit-like anterior canal.
Shell height 7.0–8.6 mm; shell width 4.0–6.0 mm. Shell ovate, solid, semi-transparent, whitish to brown, devoid of prominent sculpture on glazed smooth surface. Apex obtuse. Growth lines on shell surface inconspicuous. Whorl 5½–6, last whorl large ca. two-thirds of shell height. Spire angle ca. 90°; somewhat extended. Sutures slightly impressed, but shallow. Aperture circular; lip thickened with paler colour (ca. 0.2–0.3 mm wide and 0.5–0.6 mm thick), not expanded to slightly expanded. Apertural lip with a furrow between inner and outer peristomes, with inner peristome thickened and cord-like. Parietal callus sharply defined and thickened with paler colour. Peristome interrupted by two canals; posterior canal ca. 1.5 mm long and 0.3 mm at its widest, continuing slightly obliquely forming narrow groove bordered by parietal tooth and extended part of apertural lip; anterior canal curved and slit-liked continuing horizontally ca. 1.7 mm. Parietal tooth thickened, long trapezoid shaped (ca. 2.0 mm high, 0.7 mm wide and 0.3 mm thick), outer border somewhat straight, located at angular corner of aperture, extending beyond apertural lip and reaching beyond the middle of last whorl, always covering posterior canal. Columellar tooth somewhat thickened, curvedly triangular shaped (ca. 0.9 mm high, 2.2 mm long and 0.3 mm thick), located next to anterior canal. Umbilicus closed. Operculum round, yellowish, transparent corneous with smooth edge.
The specific epithet is dedicated to W.H. Benson, an Irish malacologist, who made large collections of molluscs and described numerous species from India and Myanmar, especially the two oldest
This new species is found from Uthai Thani Province, central Thailand.
Shell ovate; last whorl ca. two thirds of shell height. Apertural lip thickened. Parietal tooth thickened, long fin-shaped, reaching beyond the middle of last whorl, outer border curved, covering posterior canal; columellar tooth somewhat thickened, curvedly triangular shaped, located next to slit-like anterior canal.
Known only from the type locality (
As
Shell ovate; last whorl ca. 70% of shell height. Apertural lip extremely thickened; with a furrow between inner and outer peristomes; inner peristome thickened and cord-like; parietal callus distinct. Both parietal and columellar teeth extremely thickened; parietal tooth covering posterior canal; columellar tooth next to slit-like anterior canal.
Northern Vietnam (
As
Shell ovate-fusiform; last whorl ca. 70% of shell height; suture very shallow. Apertural lip somewhat thickened, not expanded. Both parietal and columellar teeth fin-shaped and thickened; parietal tooth somewhat covering posterior canal; columellar tooth next to slit-like anterior canal.
Northern Vietnam (
The specimen of
Opercula of three mainland Southeast Asian
Distribution map of the
Shells of
Live specimens of
Figs
This species group is characterised by an indistinct to thick parietal tooth, extending from a parietal callus. When observed from lateral view, the parietal tooth continues horizontally. A columellar tooth is fin-shaped, or the outer margin is curved downward appearing as an earlobe shape covering an anterior canal. The anterior canal is either not visible or appears slit-like when observed from apertural view, where the anterior canal is as long as the apertural lip width. A posterior canal is always wide and curved outward, bulging at the outer margin, sometimes slit-like. An outer apertural lip is slightly curved (Fig.
This species group from mainland Southeast Asia contains 10 species, including five nominal species and two new species (
Specimen
Shell globose to ovate-fusiform; last whorl ca. 75–80% of shell height. Apertural lip thickened but not expanded; apertural lip curved when observed from lateral view. Columellar tooth fin-shaped or curved downward like an earlobe.
Myanmar (
Given that the holotype of
All specimens in the
Shell fusiform; last whorl ca. three quarters of shell height. Apertural lip somewhat thickened, but not expanded; apertural lip when observed from lateral view somewhat curved. Columellar tooth fin-shaped.
Cambodia and central Thailand (
As the original description did not explicitly state that the description of this species was based on a single specimen (nor could this be inferred), the designation of a holotype by
Shell globose; last whorl ca. 80% of shell height. Apertural lip thickened, but not expanded; apertural lip when observed from lateral view almost straight. Columellar tooth fin-shaped.
Eastern and northeastern Thailand (
As the original description did not explicitly state that the description of this species was based on a single specimen (nor could this be inferred), the designation of a holotype by
The type locality of this species in Bangkok, the capital city of Thailand, as designated by
Banpot Pisai Temple, Lang Suan District, Chumphon Province, Thailand,
Shell ovate-fusiform to fusiform; last whorl ca. three quarters of shell height. Apertural lip highly thickened, slightly expanded; with a furrow between inner and outer peristomes; inner peristome thickened, cord-like; apertural lip curved when observed from lateral view. Columellar tooth curved downward like an earlobe.
Shell height 4.0–8.4 mm; shell width 4.4–5.7 mm. Shell ovate-fusiform to fusiform, solid, semi-transparent, whitish to pale brown, devoid of prominent sculpture on glazed smooth surface. Apex obtuse. Growth lines on shell surface inconspicuous. Whorls 5½–6, last whorl large (ca. three quarters of shell height) and bulging slightly. Spire angle ca. 80°, somewhat extended. Sutures slightly impressed, but shallow. Aperture circular; lip thickened to highly thickened (ca. 0.5–0.6 mm wide and 0.3–0.6 mm thick) with paler colour, slightly expanded; apertural lip curved when observed from lateral view. Apertural lip with a furrow between inner and outer peristomes, with inner peristome thickened and cord-like. Parietal callus sharply defined and thickened with paler colour. Peristome interrupted by two canals; posterior canal ca. 0.8–0.9 mm long, 0.5 mm at its widest, curved outward and bulging at outer margin; anterior canal slit-like, as long as apertural lip width. Parietal tooth indistinct to thick; columellar tooth curved downward like an earlobe (ca. 1.5 mm long, 0.9 mm wide and 0.5 mm thick), covering anterior canal. Umbilicus closed. Operculum round, yellowish, transparent corneous with uneven edge.
The Latin specific epithet
Northeastern and southern Thailand.
This new species has a disjunct distribution and shows varying degrees of thickness of the inner peristome within specimens from the same collecting localities.
Khao Wong Cave, Ban Rai District, Uthai Thani Province, Thailand,
Shell globose; last whorl ca. 80% of shell height. Apertural lip very thickened and slightly expanded; with a furrow between inner and outer peristomes; inner peristome thickened, cord-like; apertural lip angled when observed from lateral view. Columellar tooth curved downward like an earlobe.
The globose shell shape of
Shell height 7.7–9.5 mm; shell width 5.5–7.0 mm. Shell globose, solid, semi-transparent, brown, devoid of prominent sculpture on glazed smooth surface. Apex obtuse. Growth lines on shell surface inconspicuous. Whorls 5, last whorl large (ca. 80% of shell height) and bulging. Spire angle ca. 90°, somewhat extended. Sutures slightly impressed, but shallow. Aperture circular; lip highly thickened (ca. 0.4–0.5 mm wide and 0.5–0.6 mm thick) with darker colour, slightly expanded; apertural lip when observed from lateral view angled. Apertural lip with a furrow between inner and outer peristomes, with inner peristome thickened and cord-like. Parietal callus thickened with darker colour. Peristome interrupted by two canals; posterior canal ca. 1.0–1.2 mm long, 0.6 mm at its widest, curved outward and bulging at the outer margin; anterior canal slit-like, as long as apertural lip width. Parietal tooth thick; columellar tooth curved downward like an earlobe (ca. 2.2 mm long, 1.2 mm wide and 0.5 mm thick), covering anterior canal. Umbilicus closed. Operculum round, yellowish, and transparent corneous with uneven edge.
The specific epithet is dedicated to H.H. Godwin-Austen, a British malacologist, who prominently contributed to malacological studies in South and Southeast Asia.
This new species is found in Uthai Thani Province, Thailand.
Specimen
Shell ovate; last whorl ca. 80% of shell height. Shell surface matt. Apertural lip thickened but not expanded; apertural lip curved when observed from lateral view. Columellar tooth fin-shaped.
Myanmar and an uncertain record from northern Thailand (
No material of this species was found during this survey. The specimen of
Shell ovate-fusiform; last whorl ca. 80% of shell height. Apertural lip slightly thickened and slightly expanded; apertural lip when observed from lateral view almost straight. Columellar tooth curved downward like an earlobe.
Cambodia, Laos, and an uncertain record from Thailand (
No material of this species was found during this survey. The specimens from Srakeo Province mentioned in
Shell ovate-fusiform; last whorl ca. three quarters of shell height. Apertural lip slightly thickened and slightly expanded; apertural lip when observed from lateral view almost straight. Parietal tooth small, indistinct; columellar tooth fin-shaped, not covering slit-like anterior canal.
South Vietnam (
Shell ovate-fusiform to fusiform; last whorl ca. three quarters of shell height. Apertural lip somewhat thickened but not expanded; apertural lip slightly curved when observed from lateral view. Columellar tooth fin-shaped.
Northern Vietnam (
Shell fusiform; last whorl ca. 70% of shell height. Apertural lip thickened but not expanded; apertural lip curved when observed from lateral view. Parietal callus and parietal tooth highly thickened; columellar tooth curved downward like an earlobe.
Perak and Pahang States, Malaysia (
This taxon has always been treated as a subspecies of
By comparing with the type specimen, the specimen of
Shell ovate with higher spire; last whorl ca. three quarters of shell height. Apertural lip somewhat thickened but not expanded; apertural lip when observed from lateral view angled. Columellar tooth curved downward like an earlobe.
Kelantan and Perak States, Malaysia (
Figs
This species group is characterised by an indistinct to thickened triangular or fin-shaped parietal tooth located next to a posterior canal. A columellar tooth is less thickened, never ear shaped and mostly fin-shaped, located next to an anterior canal. Both the anterior and posterior canals are either slit-like or widening toward the outer margin when observed from apertural view. An outer apertural lip is straight or slightly curved when observed from lateral view. An operculum is round, thick, flat to concave, multispiral, whitish to pale yellow, opaque corneous with smooth edge.
This species group from mainland Southeast Asia contains 13 species and one subspecies, including three nominal species, two new species (
Shell ovate to fusiform; last whorl ca. 70–75% of shell height. Apertural lip thickened to highly thickened but not expanded. Parietal tooth thickened, fin-shaped or tooth-like, always located next to but not covering posterior canal; columellar tooth fin-shaped, thickened, located next to anterior canal. Posterior canal slightly bulging outward.
Malaysia and southern Thailand (
This species has high variation in shell shape from ovate to fusiform, and the parietal tooth varies from fin-shaped to tooth-like. Despite those shell variations, we assign these shell morphs to
By comparing with the possible type specimen, the specimen of
Paralectotypes
Shell globose to ovate; last whorl ca. three quarters of shell height. Apertural lip slightly thickened but not expanded. Parietal tooth triangular, not thickened to slightly thickened, covering posterior canal but not extending beyond apertural lip; columellar tooth fin-shaped, slightly thickened, located next to slit-like anterior canal.
Cambodia (
As the original description did not explicitly state that the description of this species was based on a single specimen (nor could this be inferred), the designation of a holotype by
Shell ovate; last whorl ca. 70–75% of shell height. Apertural lip slightly thickened but not expanded. Parietal tooth sharp, tooth-like, thickened; columellar tooth fin-shaped, slightly thickened, located next to slit-like anterior canal. Posterior canal gradually widening like a keyhole.
Malaysia (
Both similar species
Pa Pha Ya Temple, Suwannakhuha District, Nong Bua Lam Phu Province, Thailand,
Shell ovate-fusiform; last whorl ca. 70% of shell height. Apertural lip thickened but not expanded. Parietal tooth triangular, thickened, covering posterior canal, approaching but not extending beyond the outer margin of apertural lip; columellar tooth fin-shaped, thickened, located next to slit-like anterior canal.
This new subspecies is slightly different from the nominotypical subspecies in having the apertural lip, and parietal and columellar teeth more thickened.
Shell height 6.0–6.6 mm; shell width 4.2–4.6 mm. Shell ovate-fusiform, solid, semi-transparent, grey to pale brown, devoid of prominent sculpture on glazed smooth surface. Apex obtuse. Growth lines on shell surface inconspicuous. Whorls 5½, last whorl large (ca. 70% of shell height). Spire angle ca. 75–80°, slightly extended. Sutures slightly impressed, but shallow. Aperture circular; lip thickened (ca. 0.2 mm wide and 0.3–0.4 mm thick) with paler colour, not expanded. Parietal callus not sharply defined and somewhat thickened with paler colour. Peristome interrupted by two canals; posterior canal slit-like ca. 0.7 mm long; anterior canal slit-like continuing horizontally ca. 0.8–0.9 mm. Parietal tooth triangular, thickened (ca. 0.7 mm long, 0.5 mm at its widest and 0.3 mm thick), covering posterior canal, approaching but not extending beyond the outer margin of apertural lip. Columellar tooth thickened (ca. 1.0 mm long, 0.3 mm at its widest and 0.3 mm thick), fin-shaped. Umbilicus closed. Operculum round, thin, flat, multispiral, whitish to pale yellow, opaque corneous with smooth edge.
The specific epithet refers to the Thai name “Isan” for the northeastern region of Thailand, where this new subspecies is mainly distributed.
Northeastern and eastern Thailand.
Although the collecting localities of this new subspecies are ca. 600 km from the known occurrence of the nominotypical subspecies, DNA data and morphometric analyses are required to demonstrate whether these Thai specimens are distinct from the Vietnamese specimens and should be elevated to specific status.
Khao Ok Talu, Mueang Phatthalung District, Phatthalung Province, Thailand,
Shell ovate; last whorl ca. three quarters of shell height. Apertural lip thickened but not expanded. Parietal tooth sharp, tooth-like; columellar tooth sharp, triangular shaped. Both anterior and posterior canals widening like keyholes bordered by its respective tooth and a small bulge of the outer lip.
Shell height 4.0–4.5 mm; shell width 5.9–6.3 mm. Shell ovate, solid, semi-transparent, whitish to pale brown, devoid of prominent sculpture on glazed smooth surface. Apex obtuse. Growth lines on shell surface inconspicuous. Whorls 5¾, last whorl large (ca. three quarters of shell height). Spire angle ca. 90°, slightly extended. Sutures slightly impressed, but shallow. Aperture circular; lip thickened (ca. 0.1–0.2 mm wide and 0.1–0.2 mm thick) with paler colour, not expanded. Parietal callus not sharply defined and somewhat thickened with paler colour. Peristome interrupted by two canals; posterior canal ca. 0.6 mm long, 0.4 mm at its widest, continuing obliquely to form a narrow groove that widens upward like a keyhole; bordered by parietal tooth and more thickened lip appearing as a small bulge. Anterior canal slit-like continuing horizontally ca. 0.7–0.8 mm, widening towards outer margin like a keyhole, bordered by columellar tooth and more thickened lip. Parietal tooth sharp, thickened (ca. 0.6 mm long, 0.4 mm at its widest and 0.2 mm thick), tooth-like. Columellar tooth thickened (ca. 0.6 mm long, 0.9 mm at its widest and 0.2 mm thick), sharp, triangular shaped. Umbilicus closed. Operculum unknown.
The specific epithet
This new species is found from Phatthalung Province, southern Thailand.
Wat Ratburana School, Lang Suan District, Chumpon Province, Thailand,
Shell ovate-fusiform; last whorl ca. 70% of shell height. Apertural lip highly thickened and slightly expanded; with a furrow between inner and outer peristomes; inner peristome thickened, cord-like. Both parietal and columellar teeth fin-shaped, very thickened, always located next to and not covering its respective canal. Posterior canal slightly bulging outward.
Shell height 6.3–6.4 mm; shell width 9.0–9.5 mm. Shell ovate-fusiform, solid, semi-transparent, reddish brown, devoid of prominent sculpture on glazed smooth surface. Apex obtuse. Growth lines on shell surface inconspicuous. Whorls 6–6½, last whorl large (ca. 70% of shell height). Spire angle ca. 80–90°; slightly extended. Sutures slightly impressed, but shallow. Aperture circular; lip highly thickened (ca. 0.4–0.5 mm wide and 0.6–0.7 mm thick) with paler colour, slightly expanded. Aperture with a furrow between inner and outer peristomes, with inner peristome thickened, cord-like. Parietal callus sharply defined and thickened with paler colour. Peristome interrupted by two canals; posterior canal ca. 1.4 mm long and 0.7 mm at its widest, slightly bulging outward, continuing obliquely and widening vertically upward when observed from lateral view. Anterior canal curved and continuing obliquely upward ca. 2.0 mm. Parietal tooth fin-shaped, highly thickened (ca. 1.5 mm long, 0.5 mm at its widest and 0.3 mm thick), always located next to and not covering posterior canal. Columellar tooth fin-shaped, highly thickened (ca. 1.9 mm long, 0.5 mm at its widest and 0.3 mm thick), located next to anterior canal. Umbilicus closed. Operculum round, thick, flat, multispiral, whitish to pale yellow, opaque corneous with smooth edge.
The specific epithet is dedicated to F. Stoliczka, a Czech palaeontologist and zoologist, who described
This new species is found only from the type locality.
Distribution map of the
Shells of
Shells of
Live specimens of
Shell globose; last whorl ca. three quarters of shell height. Apertural lip slightly thickened but not expanded. Parietal tooth sharp, tooth-like, thickened; columellar tooth fin-shaped, thickened, located next to slit-like anterior canal. Posterior canal gradually widening like keyhole.
Perak and Perlis States, Malaysia (
By comparing with the type specimen, the specimens of
Shell ovate-fusiform; last whorl ca. 70–75% of shell height. Apertural lip slightly thickened but not expanded. Parietal tooth triangular, slightly thickened, covering posterior canal, approaching but not extending beyond the outer margin of apertural lip; columellar tooth fin-shaped, slightly thickened, located next to slit-like anterior canal.
Northern Vietnam (
As the original description did not explicitly state that the description of this species was based on a single specimen (nor could this be inferred), the designation of a holotype by
Shell globose; last whorl ca. three quarters of shell height. Apertural lip very slightly thickened, not expanded. Both parietal and columellar teeth thin, sharp, tooth-like; columellar tooth next to slit-like but widening anterior canal.
Known only from the type locality (
Shell fusiform; last whorl ca. 65% of shell height. Suture very shallow. Apertural lip highly thickened but not expanded. Parietal tooth triangular, thickened, covering posterior canal, approaching but not extending beyond the outer margin of apertural lip; columellar tooth fin-shaped, thickened, located next to slit-like anterior canal.
Northern Vietnam (
As the original description did not explicitly state that the description of this species was based on a single specimen (nor could this be inferred), the designation of a holotype by
Shell fusiform; last whorl ca. 70% of shell height. Suture very shallow. Apertural lip highly thickened but not expanded. Parietal tooth sharp, tooth-like, thickened; columellar tooth fin-shaped, thickened, located next to slit-like anterior canal. Posterior canal gradually widening like keyhole.
Known only from the type locality (
As the original description did not explicitly state that the description of this species was based on a single specimen (nor could this be inferred), the designation of a holotype by
Shell yellow, ovate-fusiform; last whorl ca. three quarters of shell height. Suture very shallow. Apertural lip highly thickened but not expanded. Parietal tooth fin-shaped, thickened, not covering posterior canal; columellar tooth fin-shaped, thickened, located next to slit-like anterior canal.
Northeast Vietnam (
Shell ovate-fusiform; last whorl ca. three quarters of shell height. Apertural lip somewhat thickened, slightly expanded. Parietal tooth sharp, tooth-like, thickened; columellar tooth fin-shaped, slightly thickened, located next to slit-like anterior canal. Posterior canal widened.
Known only from the type locality (
As the original description did not explicitly state that the description of this species was based on a single specimen (nor could this be inferred), the designation of a holotype by
Shell ovate-fusiform; last whorl ca. three quarters of shell height. Apertural lip thickened but not expanded. Parietal tooth fin-shaped, thickened, located next to wide posterior canal; columellar tooth fin-shaped, thickened, located next to slit-like anterior canal.
Known only from the type locality (
As
This species has an uncertain affiliation as there is no figure in the original description or in other later works. The type series were searched for in March 2022 and could not be located in the
Distribution map of the
Shells of
Shells of
This is the first comprehensive study focusing on the family
This project was mainly funded through grants received from the Thailand Research Fund, TRF-DPG628001 and TRF-DBG6080011 to SP. The authors are grateful to all members of the Animal Systematics Research Unit members, Chulalongkorn University for their kind help during field trips in Thailand, and especially to N. Nantarat for providing the preliminary checklist of the genus