Annotated checklist of the terrestrial molluscs from Laos (Mollusca, Gastropoda)

The land area of Laos is composed of a large variety of undisturbed habitats, such as high mountainous areas, huge limestone karsts and the lower Mekong Basin. Therefore, Laos is expected to have a high species diversity, especially for the land snails. However, with respect to research on malacology, Laos is probably the least well-researched area for land snail diversity in Indochina (including Laos) over the past few centuries. The handful of species lists have never been systematically revised from the colonial period to the present, so these classifications are outdated. Herein we present the first comprehensive annotated checklist with an up-to-date systematic framework of the land snail fauna in Laos based on both field investigations and literature surveys. This annotated checklist is collectively composed of 231 nominal species (62 ‘prosobranch’ and 169 heterobranches), of which 221 nominal species are illustrated. The type specimens of 143 species from several museum collections and/or 144 species of newly collected specimens are illustrated. There are 58 species recorded as new to the malacofauna of the country, and two new replacement names are proposed as Hemiplecta lanxangnica Inkhavilay and Panha, nomen novum (Ariophantidae) and Chloritis khammouanensis Inkhavilay and Panha, nomen novum (Camaenidae). Four recently described species of the genus Amphidromus from Laos, “thakhekensis”, “richgoldbergi”, ZooKeys 834: 1–166 (2019) doi: 10.3897/zookeys.834.28800 http://zookeys.pensoft.net Copyright Khamla Inkhavilay et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. REVIEW ARTICLE Launched to accelerate biodiversity research A peer-reviewed open-access journal Khamla Inkhavilay et al. / ZooKeys 834: 1–166 (2019) 2 “attapeuensis” and “phuonglinhae” are synonymized with previously described species. In addition, thirteen nominal species are listed as uncertain records that may or may not occur in Laos. This annotated checklist may inspire malacologists to carry on systematic research in this region.


Introduction
Laos, or Lao PDR, is located in the center of the Indo-Burma region, one of the global biodiversity hotspots (Myers et al. 2000). The geographical subdivisions of the country comprise the mountainous and dry-evergreen forests in the north, massive limestone karsts, the Annamite ranges and deciduous forests in the central region, and sandstones with the Mekong floodplain and dry-dipterocarp forests in the south (King et al. 1975). These complex geographical areas associated with different climatic and vegetation conditions provide highly diverse habitats, many of which are still undisturbed, allowing the notion that Laos likely has numerous faunal and floral 'treasures' (Mittermeier et al. 2004, Prosperi et al. 2018. Several vertebrate faunal inventories have been performed and reported (see Duckworth et al. 1999). However, various groups of invertebrates well known as important bio-indicators for all types of forest (Hodkinson and Jackson 2005), especially the land snails are still poorly investigated.
The basic information on land snail biodiversity in Laos is scarce and scantly known. So far, the most likely first record dates back to around the middle of the nineteenth century. The well-known naturalist and traveller, Henri Mouhot, had explored the Indochina region especially during his fourth mission in Siam where he journeyed from Bangkok to Luang Phrabang (previously under the rule of Siam [Thailand]). The land snail collections gathered during Mouhot's travel were then sent back to England under the Hugh Cuming legacy (Dance 1980(Dance , 1986 and were primarily examined and described by L. Pfeiffer (1860aPfeiffer ( , 1861aPfeiffer ( , 1863a. However, the localities recorded by H. Mouhot were very rough and only at a broad scale, such as "Camboja", "Siam" and "Lao Mountains" (Mouhot 1864a, b). This has made the distribution range for several species to be far from certain.
Later in the late nineteenth century, the Siamese territory on the east bank of the Mekong River (forming the present-day Laos) was appended to the French colonial territories as French Indochina. Around this period, the most important explorer was the French civil servant and diplomat Auguste Pavie (his surveys so-called "Mission Pavie"), who dealed with not only diplomacy and politics but also geology and natural history (Pavie 1904). His collected natural objects included land snail specimens from French Indochina [Cambodia, Laos, Vietnam and a part of Thailand] which were subsequently examined and described by several malacologists such as C.-F. Ancey, A. Bavay, H. Crosse, P. Dautzenberg, P. Fischer and L. Morlet. There were fifty nominal species of land snails from so called "Laos" which were collected during the Mission Pavie (Fischer 1891, Fischer and, and these were the only species lists of land snails from this area. Later, the land snail collections by the French geologist H. Counillon, mainly from the Luang Phrabang area were examined and these included some 23 nominal species (Ancey 1898). In addition, land snail collections by the German orchid collector Carl Roebelen from "Boloven" which included 13 new species were studied and published by Möllendorff (1898). About 50 years later, the French geologist, Edmund  examined land snails from Pa Hia, Tran Ninh Province [probably refers to Ban Namthong, Longchaeng District, Xaisomboun Province, Laos; see Páll-Gergely et al. (2016: 13)] and described nine new species, which brought the diversity of land snails in Laos to 64 nominal species. Another fifty years later, Panha et al. (2002), Lehmann and Maassen (2004) and Maassen (2008) studied a range of land snails from various parts of Laos, recording five new taxa. The most recent treatments on Laotian land snails are from Inkhavilay et al. (2016aInkhavilay et al. ( , b, 2017 and Páll-Gergely et al. (2016, 2017b. This paper is the first comprehensive treatment to update the land snail diversity from Laos since the "Mission Pavie" by Fischer and Dautzenberg (1904). This study focuses on the list of the species that were formerly recorded in the literature and additionally collected from a two-year (2013-2014) field survey throughout the country, which yielded a number of new records. This includes the taxonomic updates, illustrations of type specimens (when possible) and photos of newly collected specimens. Although many land snail groups have been paid little attention and never been subjected to modern systematic revision, we also attempt to classify and clarify the vague taxa in a modern systematic framework. We hope that this article will provide the fundamental and overall knowledge on land snail biodiversity in Laos and inspire local biologists who are interested in the country's land snail heritages.

Sources
The data compiled in the checklist of land snails from Laos are from two main sources. The first is from the published malacological literature ranging from the nineteenth century until 2017. This historical literature, including the "Journal de Conchyliologie", is available online at www.biodiversitylibrary.org and www.archive.org. The taxa described in Thach (2018) were not taken into account in this study. Furthermore, this list includes all taxa that have the type locality or subsequent reports as recorded in the areas forming the present-day "Laos". The taxa with the type locality of "Lao Mountains, Camboja" which were described by L. Pfeiffer based on specimens from the H. Cuming ex. H. Mouhot collection are also included. This uncertain and broad-scale geographical area more likely refers to the mountainous areas of the Luang Phrabang Ranges and Petchabun Ranges in Laos and Thailand, respectively (Fig. 1). There are many taxa described by Pfeiffer (1860aPfeiffer ( , 1861aPfeiffer ( , 1863a) that were found in several localities in Laos and Thailand, but not in present-day Cambodia. Moreover, two species, Moellendorffia horrida (Pfeiffer, 1863) and Naggsia laomontana (Pfeiffer, 1863), seem to be endemic to limestone karsts in present-day Laos. Although Fischer (1973a, b) listed Camaena illustris (Pfeiffer, 1863) and Haploptychius pellucens (Pfeiffer, 1863) as being found in Cambodia, the distribution of these species has to be verified with newly collected specimens and precise location records.
The other source of information was from field surveys performed during the years 2013-2014. Land snails in Laos were sampled using direct search techniques throughout The numbers 1 to 6 are located in presentday Thailand and 7 to 9 are in Laos. The present use of location names is given in the square brackets.  the country, including the north mountainous forests, limestone areas in the central area and deciduous forests in the south (Fig. 2). Moreover, surveys were conducted in both the National Protected Areas (NPA) with permission (NUL-2013(NUL- -2014, and non-protected areas including anthropogenic and plantation areas. The direct searching 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, we searched intensively for land snails for about 1 to 2 hours by 3 to 4 well-trained assistants. All living snails and slugs were photographed before being preserved in 70% ethanol, and empty shells were air dried in mesh-bags for one to two weeks before being sorted.

Structure of the list
Species determination and identification of specimens are 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 Bouchet et al. (2017) and the generic placements follow Kobelt (1902a), Wenz (1938), Zilch (1959Zilch ( -1960 and Vaught (1989). Within each family, genera and species are listed alphabetically. Within each species or subspecies, the treatment includes the original combination of the taxon name with original spelling, references to the page(s) and plate and/or figures. The type locality is given verbatim as stated in the original publication. However, when possible the modern name and/or regional name of the type locality is provided in square brackets. The most recent usage of the locality name and distribution records that addresses the occurrences of that particular taxon in "Laos" is also provided. When possible, the type materials with catalogue numbers, the illustrations of the type specimens and/or newly collected specimens are also provided. For taxa that could not be assigned to an existing name, a provisional taxonomic name is given (for example, Trochomorpha (?) sp.). The taxa that have long been known only from the literature, where the type specimens could not be traced and no new specimen was found during the field survey were also included, where their distribution records were based on the literature.

Photo credits
Photos of the type specimens from the Molluscs Collection (IM) of MNHN are credited to the museum taken under the project E-RECOLNAT: ANR-11-IN-BS-0004, or stated otherwise. Photos of the type specimens from FMNH and HNHM are credited to Jochen Gerber and Barna Páll-Gergely, respectively. Photos of the type specimens from the other museum collections are credited to each respective museum.

Results
This annotated checklist is based on the published literature up to 2017 and field surveys from 2013 to 2014. It comprises 231 nominal species of land snail fauna in Laos. There are 24 genera and 62 species of the 'prosobranchs', and 57 genera and 169 species and nine subspecies of the heterobranchs. Among these, 221 nominal species are accompanied with figures, 67 of which are known only from the type specimens. The list also includes 11 unidentified species that were collected during our field surveys and five species known only from the literature without newly collected specimens and without indication of the type specimens. In addition, thirteen taxa are considered as uncertain records requiring verification through further surveys.  , Solem 1966, Páll-Gergely et al. 2017b).

Class Gastropoda
Remarks. No material of this species was found, and only the type specimen was examined.  5D).
Remarks. This species has a shell morphology very similar to Dioryx bacca, except it has a relatively larger shell and a shorter sutural tube.

Remarks.
No material of this species was found, and only the type specimen was examined.
Distribution. Known only from the type locality in Vietnam .
Remarks. This species is the type species of Lagocheilus Blanford, 1864.

Remarks.
No material of this species was found, and only the type specimens were examined. For the current interpretation of Pa Hia, see Páll-Gergely et al. (2016: 13).

Rhiostoma morleti Dautzenberg & Fischer, 1906
Rhiostoma morleti Dautzenberg & Fischer, 1906: 429-431, pl. 10, figs 1-4.  Thach & Huber in Thach, 2017 from Laos and Vietnam in having a long, descending and curved detached-whorl (proboscis-like detachedwhorl), an aperture opened subventrally, and with a short and complete tubular accessory respiratory structure close to the aperture. In contrast, these four nominal species have a short to absent detached-whorl, a complete tubular or canal-like accessory respiratory structure, and an aperture opened laterally.

Spiraculum Pearson, 1833
Remarks. The name Spiraculum was nominated by Pearson (1833) with Spiraculum hispidum as a type species in order to replace the name Pterocyclos Benson, 1832. This was an invalid action and Spiraculum was treated as a junior subjective synonym or a subgenus to Pterocyclos by later authors (Benson 1836: 355-358, Pfeiffer 1852: 41, Adams and Adams 1855. Blanford (1863) discovered and described the second species, Spiraculum avanum and thus regarded Spiraculum as a valid genus. Kobelt (1902a: 171) incorrectly proposed a new replacement name, Pearsonia to replace Spiraculum due to the synonym, as he stated in the footnote that "The previously used name Spiraculum was introduced by Pearson as a synonym of Pterocyclos Benson". The name, Pearsonia, was subsequently adopted as a valid genus since then. However, this substitute name was invalid as the name Spiraculum was never preoccupied (ICZN 1999, Art. 60 (Fig. 12F).
Distribution. Known only from the type locality in Laos (Thach 2017).

Remarks.
There are two different original spellings "vilvensi" in the species description and "viviensis" in the figure caption. However, "viviensis" seemed to be an inadvertent error, since the author clearly proposed this species name in honor to "Claude Vilvens". Remarks. These specimens differ from Spiraculum massiei and S. vilvensi from Laos and Pterocyclos huberi Thach, 2015, S. franzhuberi (Thach, 2017) andS. thachi (Huber in Thach, 2017) from Vietnam in having a short complete tubular accessory respiratory structure located close to the aperture and projecting forward to the aperture. In comparison, S. massiei has a long complete tubular accessory respiratory structure located further away from the aperture and projecting up to the apex. Spiraculum vilvensi has a long complete tubular accessory respiratory structure laying in the suture and projecting backwards to the aperture, and an apertural lip expanded near the suture (see Thach (2017) for comparison). Pterocyclos huberi has an expanded lip forming a canal-like accessory respiratory structure and projecting forward to the aperture. Spiraculum franzhuberi and S. thachi have both an expanded lip forming a canal-like accessory respiratory structure and a short tubular accessory respiratory structure located away from the aperture (see Thach (2017) for comparison).

Remarks.
No material of this species was found, and only the type specimen was examined.

Remarks.
For the correct authorship of the name, see Wood and Gallichan (2008: 66).

Remarks.
No material of this species was found, and the type specimen could not be traced. This species was figured in Saurin (1953: pl. 4, fig. 3a, see Fig. 17A). For the current interpretation of Pa Hia, see Páll-Gergely et al. (2016: 13).
Remarks. These specimens differ from Diplommatina bifissurata in having less whorls (5 or 6), a circular aperture without anterior canal and protrusion, and with a strong columella tooth, while the latter species has 8 whorls, an anterior canal well developed resulting in a short protrusion on apertural lip, and with a small columellar tooth.  15D). Specimens from Nam Ork Roo, Ban Nathong village, Namo District, Oudomxay Province (Fig. 15E). Distribution. Vietnam (Do et al. 2015, Páll-Gergely et al. 2015.

Remarks.
No material of this species was found, and only the type specimen was examined.

Remarks.
No material of this species was found, and only the type specimens were examined.  Grimpe and Hoffmann 1925: 388, 390-392. Hoffmann 1925: 179-181, 256, 257. Solem 1966. Distribution. The origin of this species is probably from East Africa (Bequaert 1950). Currently it has been introduced to many tropical countries including all over Laos and Thailand.
Distribution. Known only from the type locality "Mong Sing, Siam Boundary" which is now located in Luang Namtha Province of Laos (Godwin-Austen 1920).
Remarks. No material of this species was found, and only the type specimens were examined.
Remarks. This species occurs in both natural and transformed anthropogenic habitats. This widespread and pan-tropical species has been introduced into many countries, including in greenhouses, and occurs throughout Laos and Thailand.

Distribution. Laos and Vietnam (Schileyko 2011).
Remarks. No material of this species was found, and only the type specimen was examined.

Family Enidae Woodward, 1903
Apoecus Kobelt, 1902 Remarks. All enid species from Southeast Asia have recently been assigned to the genus Coccoderma Möllendorff, 1901(Schileyko 2011, Köhler et al. 2017). However, this generic name is preoccupied by Coccoderma Zittel, 1887 (a fossil fish) and thus is not available. Here we provisionally assigned the Laotian species to the genus Apoecus Kobelt, 1902 (type species Bulimus colonus Möllendorff, 1895 from New Guinea) which has the closest distribution range to the taxa studied (Köhler et al. 2017). However, additional anatomical and molecular studies are required to confirm the taxonomic position.  ).

Remarks.
No material of this species was found, and only the type specimen was examined. For the current interpretation of Pa Hia, see Páll-Gergely et al. (2016: 13).

Remarks.
No material of this species was found, and only the type specimens were examined. Nordsieck (2002) and Páll-Gergely and Szekeres (2017)   Distribution. Known only from the type locality in Laos (Nordsieck 2002).

Remarks.
No material of this species was found, and only the type specimens were examined. Páll-Gergely and Szekeres (2017: 515) questioned the status of this subspecies as its slight difference could also be seen in the specimens from Thakhek District.

Remarks.
No material of this species was found, and only the type specimens were examined. The original description did not include an illustration. Later, Zilch designated and illustrated the lectotype of the species (Zilch 1954a: pl. 2, fig. 22; see Fig. 17F).

Remarks.
No material of this species was found, and only the type specimen was examined.

Remarks.
No material of this species was found, and the type specimen could not be traced. This species was figured in Saurin (1953: pl. 4, fig. 10a, see Fig. 17G). For the current interpretation of Pa Hia, see Páll-Gergely et al. (2016: 13).
Remarks. These specimens differ from Quantula weinkauffiana in having a smaller shell, upper shell surface with prominent nodules arranged on transverse ridges, and these ridges diminish below the periphery. In contrast, Q. weinkauffiana has a larger shell, an upper shell surface with smooth transverse ridges that terminate at the peripheral keel, and a smooth surface below the periphery.  33C). Specimens from limestone hills at Ban Oudom village, Pakbeg Ditrict, Oudomxay Province (Fig. 33D).

Remarks.
These specimens differ from all other known species in Indochina by having a trochiform with a dome-shaped shell with the upper periphery dome-shaped and the lower periphery flattened; the shell is thickened and relatively large; last whorl with a sharp peripheral keel; upper periphery with irregular growth lines and brownish subsutural band; aperture angulated, lip simple and slightly thickened; umbilicus widely open and deep.
The generic assignment of this species in Trochomorpha s.l. is still provisional, and additional anatomical studies are necessary to confirm the systematic position of this species.
Remarks. These specimens obviously differ from Trochomorpha paviei by having a trochiform shell with the upper periphery dome-shaped and the lower periphery flattened; shell thickened, with monochrome dark brown colour; shell surface with thin transverse ridges; apertural lip slightly thickened; umbilicus open and deep. In contrast, Trochomorpha paviei has a trochiform shell with the upper periphery depressed, dome-shaped and the lower periphery convex; shell thin, translucent with monochrome brownish colour; apertural lip simple; umbilicus widely open and deep.
The generic assignment of this species in Trochomorpha s.l. is still provisional, and additional anatomical studies are necessary to confirm the systematic position of this species.
Remarks. These specimens are similar to Trochomorpha bicolor Martens, 1864, but the distinct characters are an elevated conical shell with flattening below the periphery, and a narrower and deep umbilicus.
The generic assignment of this species in Trochomorpha s.l. is still provisional, and additional anatomical studies are necessary to confirm the systematic position of this species. Distribution. Cambodia, Laos, Thailand and Vietnam (Schileyko 2011 ; Fig. 34C).

Remarks.
No material of this species was found, and only the type specimen was examined.
Distribution. Known only form the type locality in Laos (Kobelt 1902b).

Remarks.
No material of this species was found, and only the type specimen was examined.

Remarks.
No material of this species was found, and only the type specimen was examined.
Remarks. The genus was first described from Peninsula Malaysia. These semi-slugs were founded on pomelo (Citrus maxima Merr) leaves. This is probably the second species of the genus. However, the genitalia characters of the type species are still unknown (Schileyko 2003a Distribution. Cambodia, Laos, Thailand and Vietnam , Solem 1966, Schileyko 2011.
Distribution. Known only from the type locality in Laos (Thach 2017).

Remarks.
No material of this species was found, and only the type specimens were examined.
Distribution. Known only from the type locality in Laos (Thach 2017).
Remarks. The genus Helminthoglypta Ancey, 1887 is mainly distributed in the California and northwest of Mexico (Schileyko 2004(Schileyko : 1722. In addition, the Xanthonychidae, to which this genus belongs, is mainly distributed in the New World: Central America, North America and north of South America (Schileyko 2004) and has never been recorded in the Oriental region. Placing this species in the Helminthoglypta seemed inappropriate. The medium size (width 27-34 mm and height 18-23 mm), rimate umbilicus, thin wrinkle shell surface and simple apertural lip make this species more closely resemble the genus Hemiplecta. However, examination of the genitalia anatomy is required to confirm their systematic position.

Remarks.
No material of this species was found, and only the type specimens were examined. The generic placement of this species is provisional. We placed this species into Macrochlamys s.l. because it has a depressed conic shell, thin and translucent shell, smooth and shining shell surface, with 4 to 7 whorls and the last whorl rounded, and a simple apertural lip. However, this species differs slightly from Macrochlamys s.l. in having varices and a widely opened umbilicus (see Godwin-Austen (1883: 76-84) and Blanford and Godwin-Austen (1908: 77-79) for further comparison).

Remarks.
No material of this species was found, and only the type specimens were examined. Recently, Schileyko (2011) placed this species within the semi-slug genus Megaustenia. However, the syntypes have 5 or 6 slowly increasing whorls and a narrowly opened umbilicus, so it is more appropriate to relocate it to Macrochlamys s.l. This generic placement is provisional and waiting for future genitalia information. Note that Souleyet (1852: pl. 28, fig. 15) illustrated a live specimen with large mantle lobes, and without a caudal foss and caudal horn on the posterior end of the body, which is distinct from the typical Indian Macrochlamys s.l. (see Godwin-Austen (1883: 76-84) and Blanford and Godwin-Austen (1908: 77-79) for further comparison).

Remarks.
For the correct authorship of the name, see Wood and Gallichan (2008: 66).

Remarks.
No material of this species was found, and only the type specimens were examined.

Distribution. Laos and Thailand (Martens 1867, Saurin 1953).
Remarks. No material of this species was found, and only the type specimen was examined.

Distribution.
Known only from the type locality in Laos ).

Remarks.
No material of this species was found, and the type specimen could not be traced. This species was figured in Saurin (1953: pl. 4, fig. 8a; see Fig. 17H). For the current interpretation of Pa Hia, see Páll-Gergely et al. (2016: 13).
Remarks. No material of this species was found, and only the type specimens were examined.
Remarks. The holotype of Amphidromus thakhekensis Thach & Huber, 2017 is identical to the un-banded colour form of A. fuscolabris, which probably reflects intrapopulation variation rather than separate biological species entities. Therefore, we recognised this name as a junior synonym of A. fuscolabris.
Distribution. Known only from the type locality in Laos (Thach 2017).

Remarks.
No material of this species was found, and only the type specimens were examined.

Remarks. Amphidromus richgoldbergi
Thach & Huber, 2017 has a dextral shell, yellowish-green periostracum and a brownish spot on the apex (Thach 2017). These characters are the intraspecific variations of A. givenchyi Panha 2006, Inkhavilay et al. 2017) rather than indicative of different biological species entities. Therefore, we recognised this name as a junior synonym of A. givenchyi.
Remarks. The holotype of Amphidromus attapeuensis Thach & Huber, 2017 has a greenish shell, purple lip and parietal callus, and brownish streaks on the apical whorls (Thach 2017). These characters are identical to that of the banded colour form of A. haematostoma (see Inkhavilay et al. 2017). Therefore, we recognised this name as a junior synonym of A. haematostoma.
Distribution. Known only from the type locality in Laos (Thach 2017).

Remarks.
No material of this species was found, and only the type specimens were examined.
Distribution. Known only from the type locality in Laos (Inkhavilay et al. 2017).

Remarks.
No material of this species was found, and only the old specimens were examined.

Remarks.
No material of this species was found, and only the type specimens were examined.
Remarks. No material of this species was found, and only the type specimens were examined.
Remarks. No material of this species was found, and only the type specimen was examined.
Distribution. Known only from the type locality in Laos (Inkhavilay et al. 2017).
Distribution. Known only from the type locality in Laos (Inkhavilay et al. 2017).
Distribution. Known only from the type locality in Laos (Thach 2017).
Remarks. This species was originally placed in the genus Megalacron Rensch, 1934. It seemed inappropriate since all the known members are distributed in the Bismarck and Solomon Islands. Moreover, the subfamily Papuninae where Megalacron belongs has a restricted distribution in New Guinea, Australia and Melanesia (Schileyko 2003b(Schileyko : 1605(Schileyko , 1606. With a medium shell size, depressed helicoid, expanded lip and rimate umbilicus, they are practically identical to the generic characters of Chloritis s.l., although this placement requires further anatomical study for confirmation. By relocating Megalacron huberi Thach, 2017 to the genus Chloritis, it becomes a junior secondary homonym of Chloritis huberi Thach, 2016 (see below). According to the ICZN guideline (ICZN 1999: Arts 57.3.1 and 60.3), the species name of a junior homonym has to be replaced, and so we propose Chloritis khammouanensis Inkhavilay & Panha, nomen novum as the new replacement name.
Distribution. Known only from the type locality and Khammouan Provinces (Thach 2017).

Distribution. Vietnam and Laos (Schileyko 2011).
Remarks. No material of this species was found, and only the type specimen was examined. As Schileyko (2011) did not give the exact locality and reference to the record of this species in Laos, and all other previous records were from "Annam" [the old name for Vietnam] (Siriboon et al. 2014a), the occurrence of this species in Laos is questionable. Distribution. Laos and Vietnam (Schileyko 2011).

Remarks.
No material of this species was found, and only the type specimen was examined. Schileyko (2011) listed this species as occurring in Laos from the Elephant Mountains. However, this locality is possibly more likely to be the Elephant Islet of Ha Long Bay, Quang Ninh Province, Vietnam. Thus, the occurrence of this species in Laos is questionable.

Remarks.
No material of this species was found and the type specimen could not be traced. This species was figured in Morlet (1887: pl. 12, fig. 5;see Fig. 17I). Schileyko (2011) listed this species as occurring in Laos from the Elephant Mountains. However, this locality is possibly more likely to be the Elephant Islet of Ha Long Bay, Quang Ninh Province, Vietnam. Thus, the occurrence of this species in Laos is questionable.
Remarks. No material of this species was found in this study and no specimen with a precise locality from Indochina has been recorded so far. Only the type specimens were examined, and the type specimen is illustrated herein for the first time. The species was originally described from West Papua, Indonesia (Pfeiffer 1864). Later, Pfeiffer (1868a) recorded this species from "Lao Mountains, Cambojae" based on H. Mouhot specimens. Since then, subsequent records followed the previous literature without specimens from Indochina. Thus, we place this species as an uncertain record in Laos.

Remarks.
No material of this species was found, and only the type specimen was examined. The type locality is mentioned as "Ménam-Pinh, Laos occidental" where Schileyko (2011) attributed this locality to Laos. However, this locality is probably the Ping River which flows from Chiang Mai to Lamphun, Tak, Kampang Phet and Nakhon Sawan Provinces in Thailand. This species has been collected from several localities in Chiang Mai, Lamphun and Tak Provinces, so these are likely to be a more precise type locality. Thus, the occurrence of this species in Laos is questionable. Material examined. Holotype NHMUK 1899.12.18.38 (Fig. 60A).

Distribution. Laos and Vietnam (Schileyko 2011).
Remarks. No material of this species was found, and only the type specimen was examined. Schileyko (2011) listed this species as occurring in Laos from Ban Lao. However, this locality is more likely to be Ban Lao in Muong Bum Commune, Thuan Chau District, Son La Province, Vietnam. Thus, the occurrence of this species in Laos is questionable.
Remarks. The relatively small size, and a simple apertural lip without constriction all probably indicate that the type specimens are juveniles. In the original description, Thach (2016) compared this new species with Chloritis bifoveata (Benson, 1856b: 251) from Myanmar instead of the proximal species, Chloritis diplochone from Southern Laos . However, a biconcave shell shape with a narrow umbilicus and spire side, and the last whorl superimposed on the penultimate whorl are likely to be unusual distinguishing characters of the species. As this species is similar to Chloritis diplochone (Fig. 48D, E), we surmise that this species could possibly occur in Laos. Therefore, we follow the original identification and wait for additional adult specimens to clarify the species status and its distribution range.