[Mollusca • 2026] Landouria tumpeesuwanorum & L. flagellolonga • Molecular Phylogeny of recognised Thai Landouria Species (Gastropoda: Camaenidae), with Descriptions of Two New Species

 

Landouria tumpeesuwanorum & L. flagellolonga  

 Nahok & K. Tanmuangpak, 

in Nahok, Chanlabut et Tanmuangpak, 2026. 

DOI: doi.org/10.3897/zookeys.1278.172545

Abstract

The molecular phylogeny and morphological–anatomical characteristics of the terrestrial snail genus Landouria Godwin-Austen, 1918 from Thailand are investigated, and we describe two new species. Phylogenetic analysis of 11 recognised Thai Landouria species reveal that these species are phylogenetically well separated from each other by mtDNA phylogeny and COI sequence divergences of 0.048–0.192. Landouria tumpeesuwanorum sp. nov. is described from a limestone hill in Nong Bua Lamphu Province, northeastern Thailand; it is characterised by its angulated whorls, a strongly keeled shell, and small flagellum with curved ends. The second new species, Landouria flagellolonga sp. nov. is described from a limestone hill in Sa Kaeo Province, eastern Thailand. It has a conical-lenticular, sharply keeled shell, and a very long, slender flagellum.

Key words: 16S rRNA, Camaenidae, COI, genitalia, integrative systematics, phylogeny, taxonomy, terrestrial snail, Thailand

Systematics

Family Camaenidae Pilsbry, 1895

Subfamily Bradybaeninae Pilsbry, 1934

Tribe Aegistini Kuroda & Habe, 1949

Genus Landouria Godwin-Austen, 1918

 

Living adults of two Landouria new species.
A. Landouria tumpeesuwanorum sp. nov. (paratype: NHLRU027); B. L. flagellolonga sp. nov. (paratype: ZCPRU-0050).

Landouria flagellolonga Nahok & K. Tanmuangpak, sp. nov.

Etymology. Specific epithet derived from Latin word longus, meaning “long” and referring to the elongated flagellum of this species.

Diagnosis. Shell small, light brown-corneous, sharply keeled. Flagellum very long, epiphallus long and slender; penis long, cylindrical, dilated at its middle part; vagina and free oviduct short. Radula with lanceolate central and lateral teeth.

Landouria tumpeesuwanorum Nahok & K. Tanmuangpak, sp. nov.

Diagnosis. Shell large, brownish-corneous, angulated whorls, strongly keeled. Flagellum small with blunt ends; epiphallus cylindrical and abruptly tapering at its distal part; penis swollen at its basal; vagina large and bulged. Radula with triangular central and lateral teeth.

Etymology. In honour of Assoc. Prof. Chanidaporn Tumpeesuwan and Sakboworn Tumpeesuwan, Thai malacologists and our beloved advisor and co-advisor, respectively, who initiated the taxonomic study of Landouria in Thailand and whose inspiration has led to our study of molluscs.

 Benchawan Nahok, Utain Chanlabut and Kitti Tanmuangpak. 2026. Molecular Phylogeny of recognised Thai Landouria Species (Gastropoda, Camaenidae), with Descriptions of Two New Species. ZooKeys. 1278: 181-200. DOI: doi.org/10.3897/zookeys.1278.172545 [28 Apr 2026]

[Mollusca • 2025] Hypselostoma pongrati & H. sichomphuense, ... • Two New Species of terrestrial Microsnails of the genus Hypselostoma W.H. Benson, 1856 (Gastropoda: Eupulmonata: Hypselostomatidae) from northeastern Thailand

 

A, B. Hypselostoma pongrati sp. nov. 
 C, D. Hypselostoma sichomphuense sp. nov.  

Tanmuangpak & S. Tumpeesuwan,

in Tanmuangpak, Nahok, Chanlabut, C. Tumpeesuwan et S. Tumpeesuwan, 2025.

 DOI: doi.org/10.3897/zookeys.1265.160661

Abstract

Two new species of hypselostomatid land microsnails, Hypselostoma pongrati Tanmuangpak & S. Tumpeesuwan, sp. nov. from Nong Bua Lamphu Province and H. sichomphuense Tanmuangpak & S. Tumpeesuwan, sp. nov. from Khon Kaen Province, are described based on the morphology of their shell, radula, and genital system. Both new species are very similar in shell shape to H. phupaman from Chaiyaphum Province, possessing a double-keeled last whorl. However, H. pongrati Tanmuangpak & S. Tumpeesuwan, sp. nov. is distinguished by the absence of apertural barriers, whereas H. sichomphuense Tanmuangpak & S. Tumpeesuwan, sp. nov. possesses three apertural barriers, and H. phupaman possesses six or seven. The three species were found on isolated limestone hills in the Chaiyaphum-Khon Kaen-Nong Bua Lamphu-Loei area.

Key words: Apertural barriers, double-keeled last whorl, genital system, limestone hills, radula

Taxonomy

Family Hypselostomatidae Zilch, 1959

Genus Hypselostoma W.H. Benson, 1856

Living Hypselostoma spp.
A, B. Hypselostoma pongrati sp. nov. paratype NHLRU015;
C, D. H. sichomphuense sp. nov. paratype NHLRU033.

 Hypselostoma pongrati Tanmuangpak & S. Tumpeesuwan, sp. nov.

Diagnosis. This new species has a prominent keel on the upper part of the last whorl and a weaker keel on the lower part. Apertural barriers absent (Fig. 3A, G, H, L). Terminal part of the last whorl is adnated to penultimate whorl.

Etymology. This new species is dedicated to the late Pongrat Dumrongrojwattana, our highly respected senior who was an expert on microsnails and who provided us with many land snails references, knowledge, and inspiration.

 Hypselostoma sichomphuense Tanmuangpak & S. Tumpeesuwan, sp. nov.

 

Diagnosis. This new species differs from Hypselostoma phupaman by the presence of a non-prominent lower keel on the last whorl and the absence of basal and parietal apertural barriers. Aperture has three smooth tooth-like swellings (Fig. 4A, G–I), whereas there are no apertural barriers in H. pongrati sp. nov. (Fig. 3A, G–I). Spire shorter than the spire of H. pongrati sp. nov.

Etymology. The specific epithet sichomphuense refers to Si Chomphu District, Khon Kaen Province, northeastern Thailand, where this species was discovered.

 Kitti Tanmuangpak, Benchawan Nahok, Utain Chanlabut, Chanidaporn Tumpeesuwan and Sakboworn Tumpeesuwan. 2025. Two New Species of terrestrial Microsnails of the genus Hypselostoma W.H. Benson, 1856 (Gastropoda, Eupulmonata, Hypselostomatidae) from northeastern Thailand. ZooKeys. 1265: 49-67. DOI: doi.org/10.3897/zookeys.1265.160661

[Mollusca • 2024] Landouria bella & L. monodon • Two New Species of Landouria Godwin-Austen, 1918 (Gastropoda: Camaenidae) from Thailand, with A Key to Thai Species

Landouria bella

Nahok, Chanlabut, S. Tumpeesuwan & C. Tumpeesuwan, 2024 

DOI: 10.3897/zookeys.1208.117056

 

Abstract

The present work contains descriptions of two new species of Landouria and a key to Thai species of this genus. Landouria bella sp. nov. is described from isolated limestone hills in Ratchaburi and Phetchaburi provinces, western Thailand. This new species is characterized by its small depressed-globose shell without a peripheral keel, the presence of a small, thin lamella on the columellar side of the inner aperture, a long, cylindrical distally bent flagellum, a short penis with a rounded verge, and a short, thick free oviduct and vagina. The second new species, Landouria monodon sp. nov. is described from sandstone hills in Kalasin Province, northeastern Thailand. This species has a depressed-conic shell with a blunt peripheral keel, a thick prominent lamella on the columellar side of the inner aperture, a short, finger-shaped, distally bent flagellum, and a long penis with a small, short verge.

 

Key words: Aegistini, Bradybaeninae, radula, reproductive anatomy, shell morphology

Landouria bella sp. nov. A holotype (NHMSU-00056) B paratype (ZCPRU-0042) C, D empty shell from Khao Nang Panthurat Forest Park, Phetchaburi Province (NHMSU-00058).

Benchawan Nahok, Utain Chanlabut, Sakboworn Tumpeesuwan and Chanidaporn Tumpeesuwan. 2024. Two New Species of Landouria Godwin-Austen, 1918 (Gastropoda, Camaenidae) from Thailand, with A Key to Thai Species. ZooKeys. 1208: 347-362. DOI: doi.org/10.3897/zookeys.1208.117056

[Mollusca • 2017] Leoparreysia gen. nov. & Trapezidens gen. nov., Radiatula mouhoti, Trapezoideus panhai, ... • New Taxa of Freshwater Mussels (Unionidae) from A Species-rich but overlooked Evolutionary Hotspot in Southeast Asia

Shells of the endemic Parreysiinae taxa from the Sittaung River basin, Myanmar.
 (a) Leoparreysia canefrii Vikhrev, Bolotov et Kondakov gen. et sp. nov., Sittaung River near Taungoo, 
(b) Radiatula mouhoti Vikhrev, Bolotov et Konopleva sp. nov., Sittaung River near Taungoo, 
(c) Lamellidens brandti Bolotov, Konopleva et Vikhrev sp. nov., Pathi River, 
(d) Trapezidens obesa feae Kondakov, Konopleva et Vikhrev gen. et ssp. nov., Myit Kyi Pauk Stream,  

Scale bar = 2 cm.

in Bolotov, Vikhrev, Kondakov, Konopleva, Gofarov, Aksenova et Tumpeesuwan, 2017. 

 DOI: 10.1038/s41598-017-11957-9  

ResearchGate.net/publication/319713215

 (Photos: Ekaterina S. Konopleva).

Abstract

Southeast Asia harbors a unique and diverse freshwater fauna of Mesozoic origin, which is under severe threat of extinction because of rapid economic development and urbanization. The largest freshwater basins of the region are certainly the primary evolutionary hotspots and they attract the most attention as key biodiversity areas for conservation. In contrast, medium-sized rivers are considered low-importance areas with secondary biodiversity, whose faunas originated via founder events from larger basins during the Pleistocene, although such a scenario has never been tested by using a phylogenetic approach. In this investigation, we used freshwater mussels (Unionidae) as a model to estimate the levels of endemism within the Sittaung, a little-known remote basin in Myanmar, compared with the surrounding larger rivers (Irrawaddy, Salween and Mekong). We discovered that the Sittaung represents an exceptional evolutionary hotspot with numerous endemic taxa of freshwater mussels. On the basis of our extensive dataset, we describe two new tribes, two genera, seven species and a subspecies of Unionidae. Our results highlight that medium-sized basins may represent separate evolutionary hotspots that harbor a number of endemic lineages. These basins should therefore be a focus of special conservation efforts alongside the largest Southeast Asian rivers.

Leoparreysiini Vikhrev, Bolotov et Kondakov tribe nov. 

Pilsbryoconchini Bolotov, Vikhrev et Tumpeesuwan tribe nov.

Shells of the endemic Parreysiinae taxa from the Sittaung River basin. (a) Leoparreysia canefrii Vikhrev, Bolotov et Kondakov gen. et sp. nov., Sittaung River near Taungoo, Myanmar (holotype RMBH biv254_4). (b) Radiatula mouhoti Vikhrev, Bolotov et Konopleva sp. nov., Sittaung River near Taungoo, Myanmar (holotype RMBH biv256). (c) Lamellidens brandti Bolotov, Konopleva et Vikhrev sp. nov., Pathi River, Myanmar (holotype RMBH biv243_14). (d) Trapezidens obesa feae Kondakov, Konopleva et Vikhrev gen. et ssp. nov., Myit Kyi Pauk Stream, Myanmar (holotype RMBH biv250_4).

Scale bar = 2 cm. (Photos: Ekaterina S. Konopleva).

Shells of the endemic Pseudodontinae and Rectidentinae taxa from the Sittaung River basin.
 Pseudodontinae (a,b), including (a) Pseudodon bogani Bolotov, Kondakov et Konopleva sp. nov., Kanni River, Myanmar (holotype RMBH biv241_5), and (b) P. manueli Konopleva, Kondakov et Vikhrev sp. nov., Pyowne Stream, Myanmar (holotype RMBH biv246_3).
Rectidentinae (c,d), including (c) Trapezoideus nesemanni Konopleva, Vikhrev et Bolotov sp. nov., Tauk Ue Kupt River, Myanmar (holotype RMBH biv255_2), and (d) T. panhai Konopleva, Bolotov et Kondakov sp. nov., Kyan Hone River (holotype RMBH biv138_4).

Scale bar = 2 cm. (Photos: Ekaterina S. Konopleva).

Haplotype-level phylogeny and distribution of Indo-Chinese Unionidae.
(a) Multi-locus fossil-calibrated phylogeny based on the BEAST 1.8.4 model and obtained for the complete data set of mitochondrial and nuclear sequences (five partitions: three codons of ...
(b) Map of distribution areas. Red circles indicate our collecting localities ...

 

Ivan N. Bolotov, Ilya V. Vikhrev, Alexander V. Kondakov, Ekaterina S. Konopleva, Mikhail Yu. Gofarov, Olga V. Aksenova and Sakboworn Tumpeesuwan. 2017. New Taxa of Freshwater Mussels (Unionidae) from A Species-rich but overlooked Evolutionary Hotspot in Southeast Asia. Scientific Reports. 7, Article number: 11573. DOI: 10.1038/s41598-017-11957-9

  Researchgate.net/publication/319713215_New_taxa_of_freshwater_Unionidae_from_Southeast_Asia

[Mollusca • 2021] Landouria circinata, L. elegans, L. trochomorphoides, etc. • Five New Species of the Land Snail Genus Landouria Godwin-Austen, 1918 (Gastropoda: Camaenidae) from northeastern Thailand, with Note on Genitalia and Radula Morphology of Landouria diplogramma

A. Landouria circinata sp. nov. B. L. tuberculata sp. nov. C. L. trochomorphoides sp. nov. D. L. chloritoides sp. nov. E. L. elegans sp. nov. 

Nahok, S. Tumpeesuwan & C. Tumpeesuwan, 2021

F. L. diplogramma (Möllendorff, 1902) comb. nov.

 DOI: 10.5852/ejt.2021.767.1495

ABSTRACT

Five new species of the terrestrial snail genus Landouria Godwin-Austen, 1918 (Camaenidae) are described from northeastern Thailand, based on shell features, radular morphology, genital anatomy, and DNA sequence data: Landouria circinata sp. nov., L. tuberculata sp. nov., L. trochomorphoides sp. nov., L. chloritoides sp. nov., and L. elegans sp. nov. These species are phylogenetically well separated from each other by mtDNA phylogeny and COI sequence divergences of 0.073–0.156. The record of Thaitropis Schileyko, 2004 (currently synonymized with Landouria) in Thailand is re-interpreted as referring to L. diplogramma (Möllendorff, 1902) comb. nov.

Keywords: Camaenidae, Landouria, Thailand, systematics, phylogeny

External shell morphology of Landouria spp. from northeastern Thailand.
A. Landouria circinata sp. nov., holotype (NHMSU-00023). B. L. tuberculata sp. nov., holotype (NHMSU-00025). C. L. trochomorphoides sp. nov., holotype (NHMSU-00027). D. L. chloritoides sp. nov., holotype (NHMSU-00029). E. L. elegans sp. nov., holotype (NHMSU-00032). F. L. diplogramma (Möllendorff, 1902) comb. nov. (NHMSU-00034).

Scale bar = 10 mm.

Living adults of Landouria spp. from northeastern Thailand.
 A. Landouria circinata sp. nov. B. L. tuberculata sp. nov. C. L. trochomorphoides sp. nov. D. L. chloritoides sp. nov. E. L. elegans sp. nov. F. L. diplogramma (Möllendorff, 1902) comb. nov.

 Scale bars = 10 mm.

Benchawan Nahok, Sakboworn Tumpeesuwan and Chanidaporn Tumpeesuwan. 2021. Five New Species of the Land Snail Genus Landouria Godwin-Austen, 1918 (Gastropoda, Camaenidae) from northeastern Thailand, with Note on Genitalia and Radula Morphology of Landouria diplogramma (Möllendorff, 1902). European Journal of Taxonomy. 767(1); 142–166. DOI: 10.5852/ejt.2021.767.1495

  

[Mollusca • 2021] Aenigmatoconcha eunetis • Systematic Revision of the Limestone Karst-restricted Land Snail Genus Aenigmatoconcha (Eupulmonata: Helicarionidae), with Description of A New Species

[F, G, H] Aenigmatoconcha eunetis Pholyotha & Panha  

in Pholyotha, Sutcharit, Tongkerd & Panha, 2021.

DOI: 10.5852/ejt.2021.767.1487 

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ABSTRACT

Thai limestone karsts are known to contain a rich biodiversity of animals, especially terrestrial snails, but still require further intensive exploration to evaluate their biodiversity. To date, only a few studies on the limestone karst-inhabiting land snail genera have been published. The present work focuses on the species diversity and phylogenetic relationships of the limestone karst-restricted land snail genus Aenigmatoconcha from Thailand, based on comparative morphology and molecular evidence. The results yielded three known species (A. clivicola Tumpeesuwan & Tumpeesuwan, 2017, A. sumonthai Tumpeesuwan & Tumpeesuwan, 2018, and A. mitis (Pfeiffer, 1863) comb. nov.), plus a new species (A. eunetis Pholyotha & Panha sp. nov.). The phylogenetic analyses of partial fragments of the mitochondrial cytochrome oxidase c subunit I (COI) gene confirmed the monophyly of all recognized species and congruence with the traditional morphology-based species designations. Average uncorrected p-distances of COI sequences between species were 9.7–12.0% and within species were 0.2–4.2%. This study also provides the re-description of penial sculpture, penial sheath, flagellum, penial caecum, and mantle lobe morphology that were neglected from the type species description. The present discovery of a new species increases the known diversity of Thai land snails and will support the conservation planning to protect karst biodiversity.

Keywords: Endemic, Indochina, limestones, COI gene, DNA barcoding

 Arthit Pholyotha, Chirasak Sutcharit, Piyoros Tongkerd and Somsak Panha. 2021. Systematic Revision of the Limestone Karst-restricted Land Snail Genus Aenigmatoconcha (Eupulmonata: Helicarionidae), with Description of A New Species. European Journal of Taxonomy. 767(1), 55-82. DOI: 10.5852/ejt.2021.767.1487

 facebook.com/BioChula/photos/3087163664897206

[Gastropoda • 2019] Landouria strobiloides • First Verified Record of the Genus Landouria Godwin-Austen, 1918 (Stylommatophora: Camaenidae) from Thailand with Description of A New Species

Landouria strobiloides

C. Tumpeesuwan & S. Tumpeesuwan, 2019

RAFFLES BULLETIN OF ZOOLOGY. 67.

Abstract

A new species of land snail is described from the Suan Hin Pha Ngam Limestone Area in Loei Province, northeastern Thailand. This species is placed in the genus Landouria Godwin-Austen, 1918 based on the presence of a slightly long club-shaped flagellum with variably sized tubercles, a gametolytic sac with swollen basal part, and absence of dart sacs and mucous glands. This is the first verified record of the genus Landouria in Thailand. 

Key words. new species, Landouria, Aegista, Thaitropis, reproductive anatomy, Loei Province, Thailand 

Fig. 2. Living specimen of Landouria strobiloides, new species. Photograph by: Benchawan Nahok.

Fig. 3. Empty shell of Landouria strobiloides, new species, holotype (NHMSU-00017). Photograph by: Benchawan Nahok.

Superfamily Helicoidea Rafinesque, 1815 

Family Camaenidae Pilsbry, 1895 

Genus Landouria Godwin-Austen, 1918

Landouria strobiloides, new species

Diagnosis. Body whorl of shell with very sharp keeled, aperture slightly thickened and with a reflexed rim. Flagellum slightly long, club-shaped, with variably-sized tubercles. Base of gametolytic sac enlarged and swollen.

...

Etymology. The specific epithet strobiloides derived from the strobilus, referring to the flagellum of the new species, which looks similar to the strobilus of non-flowering plants because it possesses many tubercles on its surface. 

Remarks. The genitalia of the new species agree in general detail with the genital anatomy of congeneric species, but it has the longest tubercles on the flagellum within the genus. The anatomy of Landouria differs from Aegista by the absence of a well-developed dart sac, lateral accessory sacs, and mucous glands (Schileyko, 2004). In Thailand, the snails that have the last whorl slightly descending in front and large umbilicus were assigned to Aegista, but this needs to be confirmed by a study of their anatomical characters.

Chanidaporn Tumpeesuwan and Sakboworn Tumpeesuwan. 2019. First Verified Record of the Genus Landouria Godwin-Austen, 1918 from Thailand (Gastropoda: Stylommatophora: Camaenidae) with Description of A New Species. RAFFLES BULLETIN OF ZOOLOGY. 67; 298–305. lkcnhm.nus.edu.sg/app/uploads/2018/11/RBZ-2019-0021.pdf

 Takahiro Hirano, Yuichi Kameda, Kazuki Kimura and Satoshi Chiba. 2014. Substantial Incongruence Among the Morphology, Taxonomy, and Molecular Phylogeny of the Land Snails Aegista, Landouria, Trishoplita, and Pseudobuliminus (Pulmonata: Bradybaenidae) occurring in East Asia. Molecular Phylogenetics and Evolution. 70; 171-181. DOI:  10.1016/j.ympev.2013.09.020

[Gastropoda • 2018] Aenigmatoconcha sumonthai • A New Helicarionid Land Snail (Helicarionidae: Durgellinae) from Chumphon Province, Southern Thailand

 Aenigmatoconcha sumonthai

C. Tumpeesuwan & S. Tumpeesuwan, 2018

 RAFFLES BULLETIN OF ZOOLOGY. 66 

 Abstract

 Aenigmatoconcha sumonthai, new species, is described from Tham Chang Phueak, a limestone range in Chumphon province, southern Thailand. The external morphology of the shell and soft parts, the genital system, and radula morphology were examined and compared with the type species of the genus, A. clivicola C. Tumpeesuwan & S. Tumpeesuwan, 2017 from northeastern Thailand. Externally the new species differs from A. clivicola in having a smaller shell, presence of black bands from the base of the long tentacles to the mantle edge, and both mantle shell lobes have numerous tiny white spots and irregular black marbling. The radula comprises approximately 22–35 transverse v-shaped rows of teeth, with each row having 11–150 unicuspid spatulated teeth. In the genital system, the penis is longer than the epiphallus and the base of the gametolytic sac is longer than the middle part. 

Key words. Aenigmatoconcha, mantle shell lobes, radula, karst, endemic taxa, disjunct distribution 

Fig. 2. Aenigmatoconcha sumonthai, new species, in natural habitat at the type locality; photographs taken on June 2017. A, two snails with the dorsal shell surface complately covered by the mantle shell lobes; B, two snails with mantle shell lobes retracted. (Photograph courtesy of Mr. Montri Sumontha).

Superfamily Helicarionoidea Bourguignat, 1877

Family Helicarionidae Bourguignat, 1877

Subfamily Durgellinae Godwin-Austen, 1888

Tribe Durgellini Godwin-Austen, 1888

Genus Aenigmatoconcha C. Tumpeesuwan & S. Tumpeesuwan, 2017

Type species. Aenigmatoconcha clivicola C. Tumpeesuwan & S. Tumpeesuwan, 2017

Aenigmatoconcha sumonthai, new species

Etymology. The species is named after the collector Montri Sumontha; the specific epithet “sumonthai” is from the family name “Sumontha”.

Diagnosis. The characters distinguishing Aenigmatoconcha sumonthai, new species, from A. clivicola are the colour patterns on mantle shell lobes and body, as well as morphology of radula and genital organs. Mantle shell lobes bear irregular black marbling pattern and numerous tiny white spots (Fig. 2A). Two black bands, each running from the base of a long tentacle (eyestalk) to mantle edge, are present (Fig. 2A). Central teeth of radula have a globose unicuspid cusp, with their size smaller than the 1st lateral teeth and only the distal halves of the globose cusps emerge from the 1st lateral teeth (Fig. 4C). The epiphallus is shorter than penis, and the middle part of the gametolytic sac in the new species is shorter than in A. clivicola (Fig. 5).

....

Chanidaporn Tumpeesuwan and Sakboworn Tumpeesuwan. 2018. Aenigmatoconcha sumonthai, A New Helicarionid Land Snail from Chumphon Province, Southern Thailand (Helicarionidae: Durgellinae). RAFFLES BULLETIN OF ZOOLOGY. 66; 170–176. 

 lkcnhm.nus.edu.sg/app/uploads/2018/01/66rbz170-176.pdf

[Gastropoda • 2017] Aenigmatoconcha clivicola • Discovery of An Overlooked Helicarionid Land Snail (Helicarionidae: Durgellinae) from northeastern Thailand, with Description of A New Genus and New Species, and Note on Radula Morphology and Genital System

หอยพิศวงเขาหินปูน  |  Aenigmatoconcha clivicola

  Tumpeesuwan & Tumpeesuwan, 2017 

 lkcnhm.nus.edu.sg/nus/index.php/65

Abstract

 Aenigmatoconcha clivicola, new genus and new species, was described from a limestone hill in Loei Province, northeastern Thailand. Morphological features of the shell, genital system, and radula were examined and compared with Sophina calias and S. schistostellis from Southeastern Myanmar, and Chalepotaxis infantilis from Southern China. It differs from all previously described Sophina species due to its more flattened and depressed, thin glossy shell, and its soft parts possessing broad right and left mantle shell lobes. The radula comprises approximately 20–25 transverse V-shaped rows of teeth; each row having 17–137 unicuspid spatulate teeth. The genital system lacks an amatorial organ and has a very large cylindrical penis without a penial sheath. 

Key words: Sophina, Chalepotaxis, Aenigmatoconcha, V-shaped rows of teeth, amatorial organ, limestone dweller

Living Aenigmatoconcha clivicola, new species, in natural habitat.  

Superfamily Helicarionoidea Bourguignat, 1877 

Family Helicarionidae Bourguignat, 1877 

Subfamily Durgellinae Godwin-Austen, 1888

Tribe Durgellini Godwin-Austen, 1888 

Aenigmatoconcha, new genus 

Type species. Aenigmatoconcha clivicola, new species. 

Diagnosis. The radula possesses similar unicuspid spatulate teeth arranged in V-shaped rows. The genitalia lack an amatorial organ and possess a large, stout penis and slender elongate epiphallus. 

Etymology. “Aenigma” from the Latin word meaning something obscure, a riddle or mystery, and “concha” from the Latin word meaning snail or shell. 

Remarks. The radula and genital organs form the unique characters distinguishing Aenigmatoconcha, new genus, from other morphologically close helicarionid genera. 

Aenigmatoconcha clivicola, new species, in natural habitat. A, living snail; B, foraging behavior.

 Photographs: Kitti Tanmuangpak. 

Aenigmatoconcha clivicola, new species

Helicarionidae gen. indet.: Tanmuangpak et al., 2012: 18–24.
 Sophina sp.: Tanmuangpak. 2016: 93–94.

Etymology. The specific epithet “clivicola” comes from two Latin words: “clivus”, meaning sloping side of hill, and “-cola”, meaning dweller.

Chanidaporn Tumpeesuwan and Sakboworn Tumpeesuwan. 2017. Discovery of An Overlooked Helicarionid Land Snail (Helicarionidae: Durgellinae) from northeastern Thailand, with Description of A New Genus and New Species, and Note on Radula Morphology and Genital System. RAFFLES BULLETIN OF ZOOLOGY. 65; 181–188. 

http://lkcnhm.nus.edu.sg/nus/images/data/raffles_bulletin_of_zoology/vol65/65rbz181-188.pdf

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