Nominal taxa of freshwater Mollusca from Southeast Asia described by Dr. Nguyen N. Thach: A brief overview with new synonyms and fixation of a ...
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Ecologica Montenegrina 41: 73-83 (2021)
This journal is available online at: www.biotaxa.org/em
http://dx.doi.org/10.37828/em.2021.41.11
https://zoobank.org/urn:lsid:zoobank.org:pub:2ED2B90D-4BF2-4384-ABE2-630F76A1AC54
Nominal taxa of freshwater Mollusca from Southeast Asia described
by Dr. Nguyen N. Thach: A brief overview with new synonyms and
fixation of a publication date
IVAN N. BOLOTOV1,2, EKATERINA S. KONOPLEVA1,2,*, ILYA V. VIKHREV1,2,
MIKHAIL Y. GOFAROV1,2, MANUEL LOPES-LIMA3,4,5, ARTHUR E. BOGAN6, ZAU LUNN7,
NYEIN CHAN7, THAN WIN8, OLGA V. AKSENOVA1,2, ALENA A. TOMILOVA1,
KITTI TANMUANGPAK9, SAKBOWORN TUMPEESUWAN10 & ALEXANDER V. KONDAKOV1,2
1
N. Laverov Federal Center for Integrated Arctic Research of the Ural Branch of the Russian Academy of Sciences,
Northern Dvina Emb. 23, 163000 Arkhangelsk, Russia.
2
Northern Arctic Federal University, Northern Dvina Emb. 17, 163002 Arkhangelsk, Russia.
3
CIBIO/InBIO – Research Center in Biodiversity and Genetic Resources, University of Porto, Campus Agrário de
Vairão, Rua Padre Armando Quintas 7, 4485-661 Vairão, Portugal.
4
CIIMAR/CIMAR – Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Terminal de
Cruzeiros do Porto de Leixões, Avenida General Norton de Matos, S/N, 4450-208 Matosinhos, Portugal.
5
SSC/IUCN – Mollusc Specialist Group, Species Survival Commission, International Union for Conservation of Nature,
c/o The David Attenborough Building, Pembroke Street, CB2 3QZ Cambridge, United Kingdom.
6
North Carolina Museum of Natural Sciences, 11 West Jones St., Raleigh, NC 27601, United States of America
7
Fauna & Flora International – Myanmar Programme, Yangon, Myanmar.
8
Department of Zoology, Dawei University, Dawei, Tanintharyi Region, Myanmar.
9
Department of Science, Faculty of Science and Technology, Loei Rajabhat University, Loei, Thailand.
10
Department of Biology, Faculty of Science, Mahasarakham University, Maha Sarakham, Thailand.
*Corresponding author: es.konopleva@gmail.com
Received: 27 February 2021│ Accepted by V. Pešić: 21 April 2021 │ Published online: 26 April 2021.
In this correspondence, we present a summary of taxonomic names of freshwater Mollusca introduced by Dr.
Nguyen N. Thach, an enthusiastic and productive malacologist from Vietnam. We show that this researcher
described one new genus and 12 new nominal species of freshwater molluscs from Southeast Asia. Two of
these nominal species, Sinanodonta hunganhi Thach, 2016 and Lanceolaria bogani Thach, 2016 (Bivalvia:
Unionidae), were already considered junior synonyms of S. jourdyi (Morlet, 1886) and L. fruhstorferi
(Dautzenberg, 1900), respectively (Do et al. 2018; Đặng and Hố 2019). Here, we propose one more synonym
for the invasive Golden Apple Snail as follows: Pomacea canaliculata (Lamarck, 1822) [=Pomacea thachi
Huber in Thach, 2020 syn. nov.] (Gastropoda: Ampullariidae). Furthermore, we establish the formal
synonymy for the following taxa: Taia Annandale, 1918 [=Boganmargarya Thach, 2018 syn. nov.]; Taia
shanensis (Kobelt, 1909) [=Boganmargarya huberi Thach, 2018 syn. nov.] (Gastropoda: Viviparidae);
Brotia henriettae (Gray in Griffith & Pidgeon, 1833) [=Brotia frankhuberi Thach, 2020 syn. nov.; Brotia
bogani Thach & Huber in Thach, 2020 syn. nov.] (Gastropoda: Pachychilidae); Pila pesmei (Morlet, 1889)
Ecologica Montenegrina, 41, 2021, 73-83FRESHWATER MOLLUSCA DESCRIBED BY DR. NGUYEN N. THACH
[=Pila huberi Thach, 2020 syn. nov.] (Gastropoda: Ampullariidae); and Paludomus andersoniana Nevill,
1877 [=Paludomus huberi Thach, 2020 syn. nov.] (Gastropoda: Paludomidae). Additionally, four nominal
species are treated here as taxa inquirenda: Melanoides thachi Huber in Thach, 2020 (Gastropoda:
Thiaridae), Trochoita frankohleri Thach & Huber in Thach, 2020 (Gastropoda: Viviparidae), Paracrostoma
huberi Thach, 2018 (Gastropoda: Pachychilidae), and Pseudodon artbogani Thach & Huber in Thach, 2020
(Bivalvia: Unionidae). We also show that the publication date written on the title page of the book “New
Shells of South Asia. Volume 2” (Thach, 2020a) is a bit misleading and that this book appeared in the
printed form on 23 June 2020. The latter date is fixed here as the date of availability of taxonomic names
introduced in this work. Finally, we present an annotated checklist of freshwater Mollusca described by N.
N. Thach with approximate coordinates of the type localities and reference to corresponding river drainage
basins.
Nguyen N. Thach is a productive amateur malacologist, who initially published several faunal
reviews and guides on Mollusca from Vietnam (Thach 2005, 2007, 2012). These works were considered an
important source of taxonomic and distributional information on the regional malacofauna, at least for
freshwater taxa (Do et al. 2018). Later, this author described multiple new taxa of marine, terrestrial, and
freshwater molluscs from Southeast Asia in a series of papers and books (e.g., Thach 2016a, 2016b, 2017,
2018, 2020a). In summary, these works contain descriptions of one new genus and 12 new nominal species
of freshwater Mollusca (Appendix). The new species-group names were attributed to three bivalves and nine
gastropods. Several of these species were co-authored/authored by Franz Huber, who is an amateur shell
collector from Austria (Thach 2020a).
All the Mollusca taxa under discussion conform to the requirements of the International Code of
Zoological Nomenclature and must be considered taxonomically available names (see Appendix). The
holotypes of these nominal species were deposited in the following museums:
North Carolina Museum of Natural Sciences [NCSM], Raleigh, North Carolina, United States of America
(8 species);
Muséum National d’Histoire Naturelle [MNHN], Paris, France (2 species);
British Museum of Natural History [NHMUK], London, United Kingdom (1 species);
Royal Belgian Institute of Natural Sciences [IRSNB], Brussels, Belgium (1 species).
The protologues contain color images of the type series of each new taxon (Thach 2016b, 2016c,
2018, 2020a). It is nice to see that four names are dedicated to Dr. Arthur Bogan, a prominent American
malacologist, who is working in the NCSM (Thach 2016c, 2018, 2020a; see Appendix for detail). These
names are as follows: Pseudodon artbogani Thach & Huber in Thach, 2020 and Lanceolaria bogani Thach,
2016 [=L. fruhstorferi (Dautzenberg, 1900)] (Bivalvia: Unionidae), Brotia bogani Thach & Huber in Thach,
2020 (Gastropoda: Pachychilidae), and the genus Boganmargarya Thach, 2018 (Gastropoda: Viviparidae).
Although a complete reappraisal of N. N. Thach’s freshwater Mollusca will be published elsewhere,
here we would discuss and revise a few remarkable nomenclatural cases which appeared in this work. These
examples mostly arose because the author overlooked several historical works on the target taxa. In
particular, one genus and five nominal species were described from Lake Inle in Myanmar as follows:
Boganmargarya Thach, 2018; Boganmargarya huberi Thach, 2018; Brotia frankhuberi Thach, 2020; B.
bogani Thach & Huber in Thach, 2020; Melanoides thachi Huber in Thach, 2020; and Paludomus huberi
Thach, 2020 (see Appendix). This lake and surrounding water bodies were a focus of comprehensive
surveys, the results of which were published in a special volume of “Records of the Indian Museum” (Vol.
14, 1918) edited by the Director of the Zoological Survey of India Dr. Nelson Annandale. This 214-page
volume contains 13 chapters characterizing the geography, geology, natural history, and fauna of this lake in
detail (Annandale 1918a). Three chapters comprise the results of taxonomic and morphological research on
freshwater malacofauna from the lake (Annandale 1918b, 1918c; Prashad 1918), including the
comprehensive “Aquatic Molluscs of the Inle Lake and connected waters” with numerous shell images of
gastropods and bivalves (Annandale 1918b). Regrettable, however, N. N. Thach overlooked those historical
works, presenting a thorough taxonomic revision of freshwater molluscs from Lake Inle with descriptions of
taxa from several families such as Viviparidae, Pachychilidae, Thiaridae, Paludomidae, and others. Hence, a
genus and five nominal species described by N. N. Thach from this lake could represent junior synonyms of
some already known taxa, and certainly need a revision.
The genus Boganmargarya was introduced on the basis of conchological features alone. In the
diagnosis, it was compared with Tchangmargarya He, 2013 and Margarya Nevill, 1877 (Thach, 2018).
Unfortunately, the author was not aware of the genus Taia Annandale, 1918 that was described from
74BOLOTOV ET AL.
Myanmar. This genus was established for a group of peculiar viviparids from the Salween and Irrawaddy
river basins, reaching the maximum species diversity in Lake Inle (Annandale 1918b). In the original
description, Annandale (1918b: 124) wrote that “The shells of these remarkable species exhibit affinities both
with Vivipara (s.s.) and with Margarya, Nevill; they also have some resemblance to those of Tulotoma,
Haldeman”. Furthermore, Annandale (1918b: 124) developed a key for identification of the 11 fossil and
recent Taia species from the Shan State of Myanmar based on conchological features. Using this key, we
found that the holotype of Boganmargarya huberi undoubtedly belongs to Taia shanensis (Kobelt, 1909).
The formal synonymy is proposed here as follows: Taia shanensis (Kobelt, 1909) [=Boganmargarya huberi
Thach, 2018 syn. nov.]; and Taia Annandale, 1918 [=Boganmargarya Thach, 2018 syn. nov.] (Gastropoda:
Viviparidae).
The status of Brotia frankhuberi and B. bogani, two other nominal species described from Lake Inle,
could also be accessed based on the work of Annandale (1918b). This researcher illustrated shells of Melania
baccata elongata Annandale, 1918 (see Annandale 1918b: 115, pl. 12, figs 3–7) that are conchologically
identical to the type series of Brotia frankhuberi. The first nominal taxon was considered a junior synonym
of Brotia henriettae (Gray in Griffith & Pidgeon, 1833) (Köhler and Glaubrecht 2002), and hence Brotia
frankhuberi became a synonym of the latter species. In its turn, Brotia bogani shares the same shell sculpture
as does Brotia frankhuberi (compare pl. 5, figs 57–58 and pl. 4, figs 50–56 in Thach 2020a) but differs from
the latter taxon by the lack of dark periostracum. It became clear that the type series of Brotia bogani was
cleaned from the periostracal layer artificially or naturally. Hence, the formal synonymy is proposed here as
follows: Brotia henriettae (Gray in Griffith & Pidgeon, 1833) [=Brotia frankhuberi Thach, 2020 syn. nov.;
Brotia bogani Thach & Huber in Thach, 2020 syn. nov.] (Gastropoda: Pachychilidae).
A new Paludomus species was also described from Lake Inle, i.e. Paludomus huberi. In the original
diagnosis, this nominal taxon was compared with Paludomus siamensis Blanford, 1903. Unfortunately, the
author did not notice several Paludomus taxa described from Myanmar (e.g., Benson 1856; Nevill 1877).
Annandale (1918b) identified two shells from Lake Inle as Paludomus ornatus Benson, 1856. However,
Paludomus huberi is more similar to P. andersoniana Nevill, 1877 from northern Myanmar (“Upper
Burma”). The latter taxon was described as follows: “Large and globose; spire produced and pointed; of a
very striking greenish yellow colour, with four intense black bands on the last whorl, the one at the suture
and the two near the base about the width of the broadest band on P. ornata; the second band from the
suture twice this width, this latter, in all but very old specimens, is very distinctly visible within the aperture;
whorls seven, the first two or three generally decollated, transversely superficially ridged, ridges more or
less obsolete towards the centre of the upper whorls, one of them below the suture more prominent that the
rest; columella pure white” (Nevill 1877: 35). It is clear that Paludomus huberi and P. andersoniana are
conspecific based on the identical shell shape, similar size, and the same coloration patterns. The formal
synonymy is proposed here as follows: Paludomus andersoniana Nevill, 1877 [=Paludomus huberi Thach,
2020 syn. nov.] (Gastropoda: Paludomidae).
The nominal taxon Pomacea thachi described from Laos is a striking example of incorrect
identification of an alien and economically important species. Recent phylogenetic and phylogeographic
surveys have shown that only two Pomacea species were introduced to Asia (Hayes et al. 2015; Yang et al.
2018). It is clear that Pomacea thachi is conspecific with P. canaliculata (Lamarck, 1822), the invasive
Golden Apple Snail, native to South America (Joshi et al. 2017). Currently, this introduced species is
common and widespread throughout Laos and other Southeast Asian countries, where it inhabits a variety of
stagnant waters such as paddy fields, swamps, canals, ponds, and lakes (Halwart 1994; Carlsson and
Lacoursiere 2005; Ng et al. 2020). It is unclear why the author (F. Huber in this case) compared the type
series of Pomacea thachi with P. maculata Perry, 1810 only (see Thach 2020a: 21), while the presence of
another alien species, P. canaliculata, in Laos was omitted completely in the differential diagnosis. Indeed, it
is itself an unfortunate failure but this taxonomic novelty may strongly affect the management of invasive
pest species in the region. Therefore, we propose the formal synonymy here: Pomacea canaliculata
(Lamarck, 1822) = Pomacea thachi Huber in Thach, 2020 syn. nov. (Gastropoda: Ampullariidae).
Pila huberi Thach, 2020 is another example of a new nominal species, the diagnosis of which was
developed on the basis of incomplete taxonomic analyses. This taxon was compared with Pila ampullacea
(Linnaeus, 1758), P. gracilis (Lea, 1856), P. scutata (Mousson, 1848), and P. polita (Deshayes, 1830)
[currently P. virescens (Deshayes, 1824)] (Thach 2020a). Unfortunately, the author did not include reference
to Pila pesmei (Morlet, 1889), a conchologically variable species, which often shares a flattened spire and
somewhat triangular shell shape (e.g., Brandt 1974; Ng et al. 2020). The deep black periostracum of the type
Ecologica Montenegrina, 41, 2021, 73-83 75FRESHWATER MOLLUSCA DESCRIBED BY DR. NGUYEN N. THACH
shells of Pila huberi almost certainly resulted from an exposition in organic-rich anaerobic sediments of a
highly eutrophic water body such as paddy fields mentioned in the original description (Thach 2020a).
Samples of gastropod and bivalve shells from such tropical water bodies often share similar glossy-black
coloration (Bolotov, pers. observ., 2012–2020). Anyway, the periostracum color cannot be used as a
diagnostic character for freshwater molluscs (both gastropods and bivalves) due to its high environment-
induced variability. The formal synonymy is proposed here as follows: Pila pesmei (Morlet, 1889) [=Pila
huberi Thach, 2020 syn. nov.] (Gastropoda: Ampullariidae).
Other nominal species such as Melanoides thachi, Trochoita frankohleri Thach & Huber in Thach,
2020, Paracrostoma huberi Thach, 2018, and Pseudodon artbogani Thach & Huber in Thach, 2020 belong
to taxonomically complicated and conchologically variable groups of Mollusca (see comments in Appendix).
Indeed, species-level taxa within such groups can be delineated by means of a molecular approach only. A
description of a new species in such a group using a few shells from a single locality in the absence of
available molecular data looks exactly like playing Russian roulette with taxa. Therefore, we prefer to assess
the status of these nominal species in the future based on a more scientifically valid ground despite the fact
that they were introduced using conchological features alone. However, the taxonomic status of these taxa
cannot be justified on the basis of original diagnoses, and we would treat the four nominal species, listed
above, as taxa inquirenda until the validity of their species-level status is confirmed.
The publication date of a taxonomic work is essential to estimate the priority of described taxa,
especially when such a work introduces a large number of new names. Regrettably, however, the publication
date of the book “New Shells of South Asia. Volume 2” (Thach 2020a) indicated on the title page (“First
published in April 8th, 2020”) is a bit misleading, most likely due to a typo. This book could not have been
published on 8 April 2020, as on 24 April 2020 its author requested permission to use a shell photo from
Bolotov et al.’s (2017b) work (Bolotov, pers. comm., 2020) that appeared in the printed book later on (Thach
2020a: 189, fig. 992). On 23 June 2020, Thach sent an e-mail to several malacologists worldwide (Bolotov
and Bogan, pers. comm., 2020). This e-mail contained three attachments, i.e. front and back cover images of
the book, and a letter addressed personally to a given scientist and dated 23 June 2020. In the letter, Thach
(2020b) stated that: “With this email, I would like to present my new shell book (written in English) with one
New Genus and 140 new Species and Subspecies that has been published”. Based on the author’s statement
and the date posted on the letter, we conclude that this self-published book has appeared in a printed form on
23 June 2020. Hence, this date is fixed here as the book’s publication date, being available for further
taxonomic revisions of the corresponding genus and species-group names. This recent issue with a
misleading printing date of the book partly resembles that with Isaac Lea’s dates of publication before 1850.
Bogan and Bogan (2002) described that historical example in detail. It was because Lea used the date the
paper was read before a meeting, instead of the date when the paper was actually published. The time
elapsed between the manuscript presentation and the actual date of its publication may have been as much as
three years (Bogan and Bogan 2002). Conrad (1853) published a paper correcting the dates of publication
and making many of Lea’s names junior synonyms.
Finally, one genus and six nominal species of freshwater Mollusca described by N. N. Thach are
considered here to be junior synonyms of older available names. Unfortunately, this researcher was not
aware of several important taxonomic works on freshwater Mollusca of Southeast Asia that led him to the
description of a few taxa that were already named by other (mostly historical) scholars. Moreover, the
identity of four nominal species belonging to conchologically variable and poorly known groups cannot be
justified for now because they were defined incompletely. Here, we consider these four nominal species as
taxa inquirenda until their validity is confirmed. Some inconsistencies in the land snails descriptions
authored by this malacologist were also noticed recently (Páll-Gergely et al. 2020; Thach 2021). However,
we would conclude that N. N. Thach made an interesting contribution to the knowledge of freshwater
Mollusca in Southeast Asia. The fully illustrated faunal books published by this scholar are of use to tropical
zoologists and malacologists, and found a place on the shelves of malacological libraries worldwide.
Acknowledgements
This study was partly supported by the Ministry of Science and Higher Education of the Russian Federation
(projects 0409-2019-0042 to O.V.A. and 0793-2020-0005 to I.N.B.). Morphological research on freshwater
Mollusca was supported by the Russian Science Foundation (project No. 21-17-00126 to I.N.B., I.V.V. and
E.S.K).
76BOLOTOV ET AL.
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Ecologica Montenegrina, 41, 2021, 73-83 79FRESHWATER MOLLUSCA DESCRIBED BY DR. NGUYEN N. THACH
Appendix
List of nominal taxa of freshwater Mollusca described by N. N. Thach with new synonyms
Class Bivalvia Linnaeus, 1758
Family Unionidae Rafinesque, 1820
Lanceolaria bogani Thach, 2016
=Unio fruhstorferi Dautzenberg (1900): 429.
=Lanceolaria bogani Thach (2016c): 9; fig. 1A–I.
Holotype: IRSNB IG.33095/MT.3235 (Royal Belgian Institute of Natural Sciences, Brussels, Belgium).
Type locality: Huế city, Thừa Thiên Huế Province, Vietnam [approx. 16.47°N, 107.58°E, Perfume
River basin].
Comments: This nominal species was considered a junior synonym of Lanceolaria fruhstorferi
(Dautzenberg, 1900) (Do et al. 2018; Đặng and Hố 2019). We agree with this decision.
Pseudodon artbogani Thach & Huber in Thach, 2020 [taxon inquirendum]
=Pseudodon artbogani Thach (2020a): 94; pl. 86, figs 986–989.
Holotype: NCSM 113635 (North Carolina Museum of Natural Sciences, Raleigh, North Carolina, United
States of America).
Type locality: “Las Freci River, near Thakhek, Laos” [approx. 17.4352°N, 104.8359°E, Mekong
River basin].
Comments: This nominal species may belong to the genus Nyeinchanconcha Bolotov et al., 2020,
which is endemic to the Mekong Basin in Laos (Bolotov et al. 2020). It needs further research because the
tribe Pseudodontini contains multiple species and genera, most of which can be distinguished by means of a
molecular approach only (Bolotov et al. 2017a, 2017b, 2020). At this stage, we would prefer to consider it as
taxon inquirendum until a more convincing proof of its validity and taxonomic placement is presented.
Sinanodonta hunganhi Thach, 2016
=Anodonta jourdyi Morlet (1886): 76.
=Sinanodonta hunganhi Thach (2016b): 7, fig. 23; 80; pl. 38, figs 472, 473; pl. 39, figs 475, 478.
=Sinanodonta jourdyi Do et al. (2018): 12.
Holotype: NHMUK 20160308 (British Museum of Natural History, London, United Kingdom).
Type locality: Around Vinh City, Nghệ An Province (North Vietnam) [approx. 18.67°N, 105.67°E,
Cả River basin].
Comments: This taxon was considered a junior synonym of Sinanodonta jourdyi (Morlet, 1886) (Do
et al. 2018; Kondakov et al. 2018; Graf and Cummings 2021). We agree with this decision. The genus
Sinanodonta contains several cryptic species that can be delineated on the basis of a molecular approach
exclusively (Bolotov et al. 2016; Bespalaya et al. 2018; Kondakov et al. 2020; Graf and Cummings 2021).
Class Gastropoda Cuvier, 1795
Family Ampullariidae Gray, 1824
Pila huberi Thach, 2020 syn. nov.
=Ampullaria pesmei Morlet (1899): 185; pl. 8, fig. 2.
=Pila pesmei Brandt (1974): 51; pl. 5, figs 70, 71.
=Pila pesmei Ng et al. (2020): 123; fig. 5B.
=Pila huberi Thach (2020a): 21; pl. 3, figs 29–38.
80BOLOTOV ET AL.
Holotype: NCSM 113628 (North Carolina Museum of Natural Sciences, Raleigh, North Carolina, United
States of America).
Type locality: Battambang, Cambodia [approx. 13.1°N, 103.2°E, Tonlé Sap Lake – Mekong River
basin].
Comments: This nominal species is a conchological form of Pila pesmei (Morlet, 1889) that was
described from Cambodia (Morlet 1899; Brandt 1974; Ng et al. 2020). Regrettably, the latter species was
overlooked in the protologue (Thach 2020a). The deep black periostracum of the type shells should reflect an
exposition in organic-rich anaerobic sediments of a highly eutrophic water body, i.e. rice fields, where the
type series was collected (Thach 2020a).
Pomacea thachi Huber in Thach, 2020 syn. nov.
=Ampullaria canaliculata Lamarck (1822): 178.
=Pomacea thachi Thach (2020a): 21; pl. 2, figs 17–24.
Holotype: NCSM 113634 (North Carolina Museum of Natural Sciences, Raleigh, North Carolina, United
States of America).
Type locality: South of Attapeu Province, Laos [approx. 14.51°N, 106.84°E, Mekong River basin].
Comments: This nominal species represents a junior synonym of Pomacea canaliculata (Lamarck,
1822), the invasive Golden Apple snail, native to South America (Joshi et al. 2017; Ng et al. 2020). This
species is a pest of rice and other aquatic plants (Halwart 1994; Carlsson and Lacoursiere 2005; Khay et al.
2018; Ng et al. 2020), and it could negatively affect native snail assemblages (Maldonado and Martín 2019).
We establish the synonymy here because we want to avoid confusion among regional researchers, pest
control managers, conservation biologists, and stakeholders in Laos and other Southeast Asian countries.
Family Viviparidae Gray, 1847
Boganmargarya Thach, 2018 syn. nov.
=Taia Annandale (1918b): 123–125 [type species: Paludina naticoides Theobald, 1865; by original
designation].
=Boganmargarya Thach (2018): 23 [type species: Boganmargarya huberi Thach, 2018; by original
designation].
Comments: This name is a junior synonym of the genus Taia Annandale, 1918. Unfortunately, Thach (2018)
was not aware of the latter genus and did not include reference to it in the protologue.
Boganmargarya huberi Thach, 2018 syn. nov.
=Vivipara shanensis Kobelt (1909): 411; pl. 77, figs 4, 5.
=Taia shanensis Annandale (1918b): 129–130; pl. 15, figs 14, 15; pl. 16, fig. 10; pl. 18, figs 4–6.
=Boganmargarya huberi Thach (2018): 23; pl. 14, figs 156–163.
Holotype: MNHN-IM-2000-34037 (Muséum National d’Histoire Naturelle, Paris, France).
Type locality: Inle Lake, Nyaungshwe Township of Taunggyi, District of Shan State, Myanmar
[approx. 20.6606°N, 96.9250°E, Salween River basin].
Comments: This nominal taxon is a junior synonym of Taia shanensis (Kobelt, 1909) based on
conchological features (see Annandale 1918b: 125, 129–130). Unfortunately, Thach (2018) completely
overlooked the work of Annandale (1918b) with a revision of Taia spp. from Lake Inle and other water
bodies of the Shan State of Myanmar.
Trochoita frankohleri Thach & Huber in Thach, 2020 [taxon inquirendum]
=Trochoita frankohleri Thach (2020a): 22; pl. 4, figs 45–48.
Ecologica Montenegrina, 41, 2021, 73-83 81FRESHWATER MOLLUSCA DESCRIBED BY DR. NGUYEN N. THACH
Holotype: NCSM 113632 (North Carolina Museum of Natural Sciences, Raleigh, North Carolina, United
States of America).
Type locality: Huahin District, Prachuap Khiri Khan Province, 200 km south of Bangkok, Thailand
[approx. 12.57°N, 99.96°E, Pran Buri River basin].
Comments: This nominal taxon seems to be a conchological variety of Trochotaia trochoides
(Martens, 1860). The latter species shares a vague type locality (Siam = Thailand) and could hardly be
distinguished from Thach’s taxon by conchological features (Brandt 1974; Li-Na et al. 2011). Small rivers
draining into the Gulf of Thailand were connected with Mekong and Chao Phraya basins via continuous
paleo-river systems during the Pleistocene (Bolotov et al. 2017a; Pfeiffer et al. 2021). However, the
morphological delineation of taxa in this genus is next to impossible, and hence we would treat Trochoita
frankohleri as taxon inquirendum until its status is confirmed based on a more convincing set of
morphological and molecular evidences.
Family Pachychilidae Fischer & Crosse, 1892
Brotia bogani Thach & Huber in Thach, 2020 syn. nov.
=Melania baccata elongata Annandale (1918b): 115; pl. 12, figs 3–7.
=Brotia henriettae Köhler & Glaubrecht (2002): 137.
=Brotia bogani Thach (2020a): 23; pl. 5, figs 57–58.
Holotype: NCSM 113629 (North Carolina Museum of Natural Sciences, Raleigh, North Carolina, United
States of America).
Type locality: Inle Lake, Myanmar [approx. 20.55°N, 96.92°E, Salween River basin].
Comments: It is unfortunate that Thach (2020a) did not notice the work of Annandale (1918b) on the
malacofauna of Lake Inle and surrounding waters. The shell appearance and sculpture of Brotia bogani are
identical to those of B. frankhuberi Thach, 2020 but the type series of the first taxon lacks the dark
periostracum due to artificial or natural cleaning. In its turn, Brotia frankhuberi is conspecific with Melania
baccata elongata Annandale, 1918 that was considered a synonym of Brotia henriettae (Gray in Griffith &
Pidgeon, 1833) [=B. baccata (Gould, 1847)] (see below for detail and references).
Brotia frankhuberi Thach, 2020 syn. nov.
=Melania baccata elongata Annandale (1918b): 115; pl. 12, figs 3–7.
=Brotia henriettae Köhler & Glaubrecht (2002): 137.
=Brotia frankhuberi Thach (2020a): 22; pl. 4, figs 50–56.
Holotype: NCSM 113630 (North Carolina Museum of Natural Sciences, Raleigh, North Carolina, United
States of America).
Type locality: Inle Lake, Myanmar [approx. 20.55°N, 96.92°E, Salween River basin].
Comments: Regrettably, Thach (2020a) overlooked the work of Annandale (1918b) on the
malacofauna of Lake Inle and surrounding waters. This nominal species is a junior synonym of Melania
baccata elongata Annandale, 1918 from Lake Inle on the basis of identical shell shape, sculpture, and size
(see Annandale 1918b: 115, pl. 12, figs 3–7). The latter taxon was considered a synonym of Brotia
henriettae (Gray in Griffith & Pidgeon, 1833) [=B. baccata (Gould, 1847)] (Köhler & Glaubrecht 2002).
Paracrostoma huberi Thach, 2018 [taxon inquirendum]
=Paracrostoma huberi Thach (2018): 23–24; pl. 15, figs 168–172.
Holotype: MNHN-IM-2000-34038 (Muséum National d’Histoire Naturelle, Paris, France).
Type locality: “300 km north of Rangon [=Yangon], Myanmar” [it might be somewhere around
Naypyidaw (the capital of the country), approx. 19.75°N, 96.11°E, Sittaung River basin].
Comments: The type locality of this nominal species is uncertain. It was also the case of some land
snail taxa introduced by N. N. Thach (see Páll-Gergely et al. 2020). The genus Paracrostoma is rather poorly
82BOLOTOV ET AL.
known (Köhler and Glaubrecht 2007). This nominal species seems to be a synonym of Paracrostoma
huegelii (Philippi, 1843), because the diagnostic features mentioned in the original description are within the
range of conchological variability of the latter species. However, taxa in this genus are almost
indistinguishable conchologically (Köhler and Glaubrecht 2007), and we prefer to consider Paracrostoma
huberi as taxon inquirendum until the separate species-level status of this taxon is confirmed on the basis of
more convincing morphological and molecular evidences.
Family Thiaridae Gill, 1871 (1823)
Melanoides thachi Huber in Thach, 2020 [taxon inquirendum]
=Melanoides thachi Thach (2020a): 23; pl. 5, figs 61–66.
Holotype: NCSM 113631 (North Carolina Museum of Natural Sciences, Raleigh, North Carolina, United
States of America).
Type locality: Inle Lake, Myanmar [approx. 20.55°N, 96.92°E, Salween River basin].
Comments: It seems to be a junior synonym of the widespread and variable species Melanoides
tuberculata (O. F. Müller, 1774) (see Annandale 1918b: 114, pl. 12, figs 1–2). It was shown that Melanoides
tuberculata sensu lato represents a complex of distant phylogenetic lineages that cannot be separated by
means of a morphological approach alone (Facon et al. 2003; Van Bocxlaer et al. 2015; Chiu et al. 2019).
The validity of Melanoides thachi cannot be justified based on the original diagnosis, and hence we would
consider it as taxon inquirendum until its full species status is reaffirmed using a body of more convincing
evidences.
Family Paludomidae Stoliczka, 1868
Paludomus huberi Thach, 2020 syn. nov.
=Paludomus andersoniana Nevill (1877): 35.
=Paludomus huberi Thach (2020a): 23; pl. 5, figs 67–68; pl. 6, 69–74.
Holotype: NCSM 113633 (North Carolina Museum of Natural Sciences, Raleigh, North Carolina, United
States of America).
Type locality: Inle Lake, Myanmar [approx. 20.55°N, 96.92°E, Salween River basin].
Comments: In the original diagnosis, this nominal taxon was compared with Paludomus siamensis
Blanford, 1903. Regrettably, however, the author overlooked several Paludomus taxa described from
Myanmar (Benson 1856; Nevill 1877; Annandale 1918b). Paludomus huberi is conspecific with P.
andersoniana Nevill, 1877 based on the identical shell shape, similar size, and the same coloration patterns
(Nevill 1877).
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