Research Article |
Corresponding author: Somsak Panha ( somsak.pan@chula.ac.th ) Academic editor: Frank Köhler
© 2022 Nem Sian Man, Thanit Siriboon, Aung Lin, Chirasak Sutcharit, Somsak Panha.
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.
Citation:
Sian Man N, Siriboon T, Lin A, Sutcharit C, Panha S (2022) Revision of the carnivorous land snail family Streptaxidae (Stylommatophora, Achatinina) in Myanmar, with description of four new species. ZooKeys 1110: 39-102. https://doi.org/10.3897/zookeys.1110.85399
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The carnivorous terrestrial snail family Streptaxidae, recognized by having a regular to eccentric shell with complex apertural dentition, remains little-known and largely unexplored in Myanmar. This article presents historically recorded species and provides new data on this family. A total of eighteen species in five genera, namely Carinartemis, Discartemon, Haploptychius, Oophana, and Perrottetia from the southeastern and eastern parts of Myanmar, is examined herein. Among these, Haploptychius is the most diverse with eight species, while the remaining genera are comprised of fewer than five species each. Streptaxis birmanica and Streptaxis blanfordianus are herein synonymized with Haploptychius blanfordi, while Streptaxis hanleyanus is synonymized with Carinartemis sankeyi. Furthermore, the first genitalia and radula descriptions for three previously known species, D. tonywhitteni, C. exacutus, and C. sankeyi, are provided. Using comparative morphological and anatomical approaches, four new species are described: D. paurodeviatus sp. nov., H. heliakosus sp. nov., H. tenasserimicus sp. nov., and H. karenorum sp. nov. This present study enhances the understanding of the land snail fauna in Myanmar, specifically the streptaxids, and highlights that limestone areas are important for biodiversity conservation.
Biodiversity, endemic, Fauna & Flora international, genitalia, limestone, systematics, taxonomy
Having the greatest land area in mainland Southeast Asia, Myanmar, formerly known as Burma, is recognized as having a high level of ecosystem diversity that can support a diverse variety of organisms and is part of the Indo-Burma biodiversity hotspot (
The members of family Streptaxidae Gray, 1860 are known as carnivorous land snails and are characterized by an eccentric to cylindrical shell with complex apertural dentition, genitalia with hook-like structures, and living animals usually having bright yellow to red or greenish bodies (
In Myanmar, the most recent reports on the superfamily Streptaxoidea (Streptaxidae and Diapheridae Panha & Naggs, 2010) were published more than one hundred years ago (see
During land snail expeditions in Myanmar in 2015 and 2016, streptaxid species were discovered in several localities in southeastern (Mon State, Kayin State, and Tanintharyi Region) and eastern (Shan State and Mandalay Region) parts of Myanmar under the cooperation of the Forest Department of Myanmar (FDM), Fauna & Flora International (FFI), and Chulalongkorn University. Herein, we discuss the taxonomy of the carnivorous terrestrial snail family Streptaxidae collected in Myanmar. The molecular phylogeny by
Streptaxid specimens were collected during 2015 and 2016 by the Animal Systematics Research Unit (ASRU) members, Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand. These field surveys were conducted under a MOU between the Forest Department, Ministry of Natural Resources and Environmental Conservation and Forestry, Myanmar and Fauna & Flora International (FFI) with Letter No. 0092. The field surveys focused on non-limestone and limestone areas in Shan State, Mon State, Kayin State, Mandalay Region, and Tanintharyi Region. The coordinates were recorded using GPS. Approximate collection localities are presented in Table
Shell measurements of streptaxid species from Myanmar recognized in this study. Numbers listed before collection locality correspond to those in the map in Fig.
Species, localities and CUMZ no. | Number of specimens | Ranges, mean ± S.D. in mm. | Number of whorls | ||
---|---|---|---|---|---|
Shell height | Shell width | H/W ratio | |||
Discartemon tonywhitteni | |||||
20. Phra (Buddha) Cave, Tanintharyi: (13001) | 7 | 3.4–5.1 4.5±0.64 | 9.5–12.7 11±1.05 | 0.27–0.5 0.4±0.08 | 6–6½ |
Discartemon paurodeviatus sp. nov. | |||||
17. Phataw Phatet Island, Tanintharyi: (13002, 13003, 13004) | 17 | 6.8–8.1 7.5±3.48 | 10.8–12 11.3±0.35 | 13.8–16.8 1.5±0.07 | 6–6½ |
Oophana mouhoti | |||||
19. Phra (Buddha) Cave, Tanintharyi: (13005) | 1 | 11.2 | 10 | 0.6 | 6½ |
Perrottetia theobaldi | |||||
3. Aik Kham Cave, Shan: (13006) | 4 | 3.6–4.2 3.8±0.31 | 5.6–5.8 5.7±0.10 | 1.4–1.6 1.5±0.10 | 5–5½ |
Haploptychius solidulus | |||||
16. Pathen mountain, Hpa-an, Kayin: (13007) | 15 | 10.8–12.4 11.6±0.61 | 11.3–12.6 11.8±0.46 | 0.9–1.1 1.02±0.03 | 6–6½ |
Haploptychius thebawi | |||||
1. Pyinyaung Village, Meiktila, Mandalay Region (Apache Cement Co. Ltd): (13008) | 4 | 7.5–9.0 7.8±0.69 | 7.5–8.7 8.1±0.51 | 0.8–1.1 1.03±0.13 | 6–6½ |
2. Lin Way Monastery, Ywangan, Shan: (13009) | 7 | 6.7–7.3 7.1±0.24 | 6.5–7.9 7.2±0.42 | 0.9–1.2 1.02±0.08 | 5½–6 |
3. Aik Kham Cave, Taunggyi, Shan: (13010) | 3 | 4.6–5.3 5.0±0.36 | 5.0–5.7 5.4±0.37 | 1.1–1.2 1.08±0.03 | 6–6½ |
Haploptychius tenasserimicus sp. nov. | |||||
18. Lampane Cave, Tanintharyi: (13011, 13012) | 5 | 4.1–5.0 4.5±0.36 | 8.1–9.7 8.7±0.59 | 1.7–2.0 1.9±0.08 | 6 |
Haploptychius heliakosus sp. nov. | |||||
9. Bardai Mountain, Hpa-an, Kayin: (13013, 13014, 13015) | 39 | 9.7–11.6 10.6±0.60 | 7.3–10.3 9.1±1.05 | 0.6–0.9 0.8±0.10 | 7–7½ |
6. Kyonknow Cave, Hpa-an, Kayin: (13016) | 7 | 8.4–9.9 9.2±0.61 | 8.1–9.9 8.9±0.57 | 0.8–1.2 0.9±0.10 | 6½–7 |
Haploptychius karenorum sp. nov. | |||||
10. Waiponla Mountain, Hpa-an, Kayin: (13017, 13018) | 6 | 11.4–12.4 11.8±0.40 | 8.2–10.0 8.9±0.70 | 0.6–0.8 0.7±0.08 | 6–7½ |
5. Taung Lay Cave, Hpa-an, Kayin: (13019) | 2 | 8.8–9.7 9.3±0.4 | 10.5–12 11.3±0.8 | 1.14–1.36 1.22±1.10 | 6½–7 |
Carinartemis exacutus | |||||
11. Sadhdan Cave, Hpa-an, Kayin: (13020) | 3 | 6.2–7.3 6.7±0.45 | 13.0–14.0 13.03±0.4 | 1.8–2.0 1.9±0.15 | 6–6½ |
4. Bayin Nyi Cave, Hpa-an, Kayin: (13021, 13022) | 23 | 6.3–6.8 6.6±0.22 | 6.8–12.6 12.2±0.4 | 1.7–2.0 1.8±0.09 | 6–6½ |
12. Lun Nga Mountain, Hpa-an, Kayin: (13023, 13024) | 64 | 5.5–6.3 5.9±0.33 | 13.2–13.9 13.5±0.28 | 2.1–2.5 2.2 ±0.16 | 5½–6 |
7. Taung Wine Cave, Hpa-an, Kayin: (13025, 13026) | 9 | 7.4–7.5 7.5±0.05 | 12.0–13.1 12.5±0.56 | 1.6–1.7 1.7±0.89 | 6–6½ |
8. Kaw Ka Taung, Hpa-an, Kayin: (13027) | 1 | 7.6 | 12 | 1.6 | 6½ |
Carinartemis sankeyi | |||||
14. Saddan Cave, Mawlamyine, Mon: (13028) | 7 | 6.9–8.3 7.6±0.51 | 9.0–10.5 9.7±0.55 | 1.2–1.4 1.3±0.11 | 6–7 |
13. Kayon Cave, Mawlamyine, Mon: (13029, 13030) | 18 | 7.0–8.2 7.5±0.49 | 9.1–10.2 9.7±0.49 | 1.2–1.4 1.2±0.07 | 6½–7 |
15. Dhammatat Cave, Mawlamyine, Mon: (13031) | 12 | 5.5–7.4 6.5±0.57 | 10.4–11.6 11.1±0.44 | 1.5–2.0 1.7±0.15 | 6–7 |
For anatomical studies, living specimens were photographed, euthanized following the protocol by the
All the nominal species names described as new to science in this work are attributed to the first and last authors (Man & Panha). Thus, a complete citation of the authors is Man & Panha in Man et al.
ag, albumen gland; at, atrium; fo, free oviduct; gd, gametolytic duct; gs, gametolytic sac; hd, hermaphroditic duct; ov, ovary; p, penis; pr, penial retractor muscle; ps, penial sheath; psr, penial sheath retractor muscle; sv, seminal vesicle; ta, talon; v, vagina; vd, vas deferens (
Materials examined in this study were deposited in the following institutions:
Discartemon
Pfeiffer, 1856: 173.
Odontartemon (Discartemon)
–
Streptaxis discus Pfeiffer, 1853, by subsequent designation by
Shell flattened to globose-heliciform. Last whorl rounded to angular, less distorted, and often with peripheral keel; whorls regularly to rapidly expanded. Apertural dentition varied, ranging from only one parietal lamella to additional dentition: upper palatal, palatal, basal, columellar and supracolumellar lamellae. Genitalia with short to long penis, sometimes with penial appendix and penial sheath covering entire penis length. Penial hooks present and vaginal hook absent.
This genus was recently revised in both shell and genital diagnostic characters, and the intrageneric relationship was discussed (
Discartemon tonywhitteni
Sutcharit & Panha in
Holotype
Living snails A Discartemon tonywhitteni from near Phra (Buddha) Cave, Tanintharyi Region (shell width ~ 10 mm) B Discartemon paurodeviatus sp. nov. from the type locality (shell width ~ 11 mm) C Haploptychius heliakosus sp. nov. from the type locality (shell height ~ 9 mm) D Carinartemis exacutus from Lun Nga Mountain, Kayin State (shell height ~ 14 mm) E, F Carinartemis sankeyi (E) from Kayon Cave, Mon State (shell height ~ 10 mm) and (F) from Saddan Cave, Mawlamyine, Mon State (shell height ~10 mm).
This species was clearly described in
Genital organs. Atrium (at) short. Penis (p) long and slender. Penial sheath (ps) thin and extending ~1/2 to 3/4 of penis length; penial sheath retractor muscle (psr) very thin, originating at atrium and inserting distally on penial sheath (Fig.
Internal wall of atrium generally smooth (Fig.
Internal sculpture of genitalia of Discartemon tonywhitteni, specimen
Vagina (v) short, ~ 1/3 of penis length. Gametolytic duct (gd) a long tube extending as far as albumin gland; gametolytic sac (gs) ovate. Free oviduct (fo) long, ~ 2 times of vagina length. Oviduct (ov) slender and folded; prostate gland inconspicuous and bound to oviduct. Talon (ta) small, short and club shaped. Hermaphroditic duct (hd) bearing long seminal vesicle (sv) ca. twice as long as the length from talon to branching point of seminal vesicle (Fig.
Vaginal wall with transverse vaginal folds; vaginal hook absent (Fig.
Radula. Each row consists of ~ 35‒49 teeth with formula (24‒17) ‒1‒ (17‒24). Central tooth very small with pointed cusp. Lateral and marginal teeth undifferentiated, unicuspid and lanceolate. Latero-marginal teeth gradually reducing in size, with outermost teeth much smaller and shorter than inner teeth (Fig.
Discartemon tonywhitteni is the southernmost distributed species and, currently, is known as the only form from the type locality (Fig.
Holotype
Small hill on Pahtaw Pahtet Island (~ 500 m west of Myeik Town), Myeik Township, Tanintharyi Region, Myanmar (12°26'3.5"N, 98°35'14.1"E).
Discartemon paurodeviatus sp. nov. can be distinguished from D. collingei (Sykes, 1902) from Malaysia by having a larger shell, rounded last whorl, semi-ovate and slightly reflected aperture, and sometimes supracollumellar lamellae are present. Compared with D. vandermeermohri van Benthem Jutting, 1959 and D. mekalostraka Siriboon & Panha, 2014 from Thailand, this new species has a slightly extended last whorl from the penultimate whorl, last whorl slightly axially deflected, widely open umbilicus, and semi-ovate aperture. The genital organs of D. paurodeviatus sp. nov. differ from D. mekalostraka by having corrugated atrium without pore, short penis, dense brownish and long slender penial hooks located on penial papillae, and short vagina with thickened and reticulated vaginal folds.
Shell globose-heliciform, white and translucent; whorls 6–6½; spire conical with distinct suture. Shell surface glossy with fine transverse ridges that diminish below periphery; varices present. Embryonic shell ~ 2½ whorls with smooth surface; following whorls regularly coiled. Last whorl rounded, little axially deflected and extruded from the penultimate whorl. Aperture semi-ovate; peristome yellowish to whitish, discontinuous, thickened, expanded, and slightly reflected. Apertural dentition with one strong parietal, one small palatal, one large basal, and one small columellar lamella; sometimes with small supracolumellar lamellae. Umbilicus open and deep (Fig.
Genital organs. Atrium (at) short. Penis (p) long and slender. Penial sheath (ps) very thin, extending entire penis length; penial sheath retractor muscle (psr) very thin, originating at atrium and inserting distally on penial sheath (Fig.
Internal wall of atrium corrugated with sparse atrial pores (Fig.
Internal sculpture of genitalia of Discartemon paurodeviatus sp. nov., paratype 13003 A junction of atrium, vagina, and proximal penis B, C lateral view of penial hooks on proximal part of penis D reticulated arrangement of penial hooks on middle part of penis E lateral view of penial hooks F arrangement of penial hooks on distal part of penis G arrangement of thickened reticulated vaginal folds.
Vagina (v) very short and stout, ~ 1/7 of penis length. Gametolytic duct (gd) a long and slender tube extending as far as albumin gland; gametolytic sac (gs) ovate. Proximal free oviduct (fo) convoluted and distally long and thick, ~ 3 times of vagina length. Oviduct (ov) enlarged and folded; prostate gland inconspicuous and bound to oviduct. Talon (ta) small, short and club shaped. Hermaphroditic duct (hd) bearing short and thickened seminal vesicle (sv) and ca. same length as from talon to branching point of seminal vesicle (Fig.
Vaginal wall generally with thickened reticulated vaginal folds, smooth surface, and vaginal pores present (Fig.
Radula. Each row consists of ~ 21‒33 teeth with formula (16‒10)‒1‒(10‒16). Central tooth small with pointed cusp. Lateral and marginal teeth largest and undifferentiated, unicuspidal, and lanceolate. Latero-marginal teeth rapidly reducing in size, with outermost teeth much smaller and shorter than inner teeth (Fig.
The specific name paurodeviatus is derived from the Greek word pauros meaning little or few and the Latin word devius meaning out of the way. It refers to the last whorl of the new species as being slightly axially deflected and extruded from the penultimate whorl.
The species is only known from the type locality in southern Myanmar (Fig.
Variation occurs in the possession of supracolumellar lamellae in some specimens. Currently, two species of Discartemon (D. paurodeviatus sp. nov. and D. tonywhitteni) have been recognized from Myanmar (
Oophana
Ancey, 1884: 508.
Odontartemon (Oophana)
–
Ennea bulbulus Morelet, 1862 by subsequent designation by
Shell globosely ovate to sub-heliciform, translucent to opaque. Penultimate whorl slightly extended beyond last whorl. Last whorl rounded or flattened along the periphery, and axially deflected from penultimate whorl. Aperture oblique-ovate to squarish; apertural dentition with parietal (one or two), palatal, basal, and columellar lamellae. Genitalia with penial sheath covering ~ 1/2 of penis length, and penial hook present.
The genus Oophana shares the ovate shell shape with the Haploptychius. However, Oophana can be distinguished by generally having a greater number of apertural dentitions (parietal, palatal, basal and columellar lamellae), while Haploptychius has only one parietal lamella (
Generally, despite Oophana and Indoartemon Forcart, 1946 possessing an ovate shell with a blunt spire, the former can be distinguished by its parietal, palatal, basal, and columellar lamellae, while the latter possesses only one parietal and one palatal lamella (
Generally, Oophana shows high variability in shell form, and apertural dentition with upper palatal and supracolumellar lamellae occurring in some species (
The phylogenetic relationships of the Oophana s.l. from Thailand were recently shown to be polyphyletic and comprised of three groups. These polyphyletic groups could possibly be recognized as distinct genera supported by their unique shell and genital characters (
Streptaxis elisa
Gould, 1856: 13. Type locality: an island in the Mergui Archipelago.
Odontartemon elisa
–
Perottetia elisa
–
Oophana elisa
–
The shell is oblique-heliciform with convex spire and a distinct suture. Whorls 7 and shell surface with transverse ridges that diminish below the periphery. Shell periphery is keeled, and last whorl axially deflected. Umbilicus open and deep. Aperture is subquadrangular, peristome reflected. Apertural dentition with one parietal, one basal, two weak palatal, and one columellar lamella.
This species is known only from the type locality, in the southern part of Myanmar. No fresh materials were collected in this survey. Herein, the description of this species is based only on the original description.
Streptaxis mouhoti
Pfeiffer, 1863 [1862]: 273. Type locality: Siam [Thailand].
Streptaxis johswichi Martens, 1864: 528. Type locality: Siam, bei Petchaburi [Petchaburi Province, Thailand].
Streptaxis mouhoti var. johswichi
–
Gonaxis mouhoti
–
Odontartemon (Oophana) mouhoti
–
Oophana mouhoti
–
Possible syntype
A, B Oophana mouhoti A possible syntype
Oophana mouhoti can be distinguished from O. obtusus (Stoliczka, 1871) by its higher spire, expanded aperture lip, deflected last whorl, and slightly angulate penultimate whorl. In contrast, O. obtusus exhibits a narrow aperture, spire convex, periphery of penultimate whorl usually equal to last whorl, strong columellar lamella, and small tubercle near the posterior angle of aperture.
Shell oblique-ovate, white, and translucent; whorls 6½; spire elevated conical with distinct suture. Shell surface glossy with fine transverse ridges that diminish below the periphery; following whorls regularly coiled. Shell periphery rounded and last whorl axially deflected. Aperture subcircular; peristome expanded, thickened, discontinuous, and reflected. Apertural dentition with one strong parietal, one small upper palatal, one small palatal, and one basal lamella. Umbilicus open and deep (Fig.
This species has been recorded from several localities in Peninsular Thailand (
The only shell was collected from the limestone hills at Buddha Cave, Tanintharyi Region; it matches well with this species.
Oophana mouhoti was originally described based on specimens in the collection of H. Cuming with the very brief collection locality given as Siam. The
Streptaxis obtusus
Stoliczka, 1871: 166, 167, pl. 7, figs 11–13, pl. 8, figs 1–4. Type locality: Prope Moulmein, provincia Tenasserim [Mawlamyine District, Mon State, Myanmar].
Odontartemon (Oophana) obtusus
–
Oophana obtusa
–
Moulmein:
Shell oblique-ovate, white, translucent; whorls 6–7; spire convex with distinct suture. Shell surface glossy with fine transverse ridges, nearly smooth with few transverse ridges near peristome. Embryonic shell ~ 2½ whorls with smooth surface; following whorls regularly coiled. Shell periphery rounded; last whorl slightly axially deflected. Aperture subcircular; peristome continuous, expanded, slightly reflected, and very short sinulus. Apertural dentition with one strong parietal, one palatal, and one strong columella lamella. Umbilicus open and deep (Fig.
This species is only known from the type locality, the southern part of Myanmar (
No new specimens were collected in this survey; however, authenticated museum specimens were examined. Regarding genitalia, Oophana obtusus and Haploptychius burmanicus were the first two species anatomically examined and illustrated among several streptaxids in Myanmar by
Streptaxis laevis
Blanford, 1899: 765, pl. 50, figs 11–12. Type locality: Tenasserim [probably Tanintharyi Region, Myanmar].
Streptaxis (Odontartemon) laevis
–
Odontartemon (Oophana) laevis
–
Indoartemon laevis
–
Possible syntype
Oophana laevis differs from O. mouhoti and O. obtusus by having a rounded penultimate whorl, convex spire, and apertural dentition with parietal and basal lamellae. Although O. mouhoti and O. obtusus have a slightly angular penultimate whorl and elevated spire, O. mouhoti usually has only a parietal lamella (sometimes with basal lamella). In contrast, O. obtusus has parietal, palatal, and columellar lamellae.
Shell oblique-heliciform, white, and translucent; whorls 5½; spire low convex with distinct suture. Shell surface glossy with transverse ridges that diminish below periphery. Embryonic shell ~ 2½ whorls with smooth surface; following whorls regularly coiled. Shell periphery rounded; last whorl axially deflected. Aperture subquadrangular with sinulus; peristome discontinuous, thin, expanded and reflected. Apertural dentition with one parietal and one basal lamella, and sometimes columellar lamella is absent. Umbilicus open and shallow (Fig.
This species is known only from the type locality, which was mentioned only as ‘Tenasserim’ (Blandford 1899). This locality possibly refers to the Tanintharyi Region, southeastern Myanmar.
No new specimens were collected in this study. However, we compared the possible type specimen with the other congeners.
Odontartemon (Perrottetia)
Kobelt, 1905: 91.
Oophana (Perrottetia)
–
Perrottetia
–
Helix perrotteti Petit, 1841 by subsequent designation by
Shell oblique-heliciform, and translucent. Longitudinal furrows present behind apertural lip. Apertural dentition usually consists of two parietal, one palatal, one basal and one columellar lamella, and upper palatal and supracolumellar lamellae may be present. Genitalia with long and slender penis, penial sheath thin and not extending the entire penis length. Penial hooks dense, pale brown, expanded at base, with pointed tips, located on penial papillae, and curved towards genital orifice. Vaginal hooks may be present.
Perrotettia and Discartemon are generally similar in having complex apertural dentition; however, their shell morphology is obviously different. Perrottetia has a sub-heliciform shell, smaller size, last whorl rounded and more or less deflected, and mostly with two parietal lamellae. Although parietal, palatal, basal and columellar lamellae are always present in Perrottetia, possession of second parietal, upper palatal and supracolumellar lamellae is variable, as is the presence of bifid lamellae (
Nonetheless, some Discartemon species from Thailand have two parietal lamellae, for example, D. afthonodontia (see
At present, the genus Perrottetia is comprised of about 30 nominal species distributed from India and Sri Lanka to Indochina and southern China (
Streptaxis theobaldi
Benson, 1859b: 187. Type locality: Nauclai (lat. 25°15', long. 92°30') [probably in Meghalaya State, India].
Odontartemon (Perrottetia) theobaldi
–
Perrottetia theobaldi
–
Syntype
UMZC I.102535 (2 shells) from unknown locality. Khasi Hill:
Perrottetia theobaldi is similar to P. dugasti (Morlet, 1892) from Vietnam; however, the former species can be distinguished by having a second parietal lamella running to the main parietal lamella, thicker and less reflected peristome, subquadrangular aperture, and shallow suture. In contrast, P. dugasti has a weak second parietal lamella running to the sinulus, thinner and more reflected peristome, semi-ovate aperture, and a deeper suture with a clear bifid columellar lamella. Similarly, P. mabillei (Bavay & Dautzenberg, 1903) from Vietnam can be separated from P. theobaldi by its strong radial ridges, wide and short sinulus, basal lamella absent, bifid columellar lamellae, and deep umbilicus, while P. theobaldi has a smooth shell surface, long and narrow sinulus, strong basal lamella, columellar lamellae separated, and shallow umbilicus. Furthermore, P. theobaldi differs from the Thai species P. aquilonaria Siriboon & Panha, 2013 by having a shallow suture, narrow and long sinulus, rounded last whorl, peristome thicker and less reflected, aperture subquadrangular and columellar lamellae are separated. In contrast, P. aquilonaria possesses deep suture, shorter and wider sinulus, the last whorl shouldered, aperture subcircular, more expanded peristome, and bifid columellar lamella.
Shell sub-oblique heliciform, white, and translucent; whorls 5–5½; spire convex with distinct suture. Shell surface glossy with transverse ridges that diminish below periphery. Embryonic shell ~ 2½ whorls with smooth surface; following whorls regularly coiled. Shell periphery rounded; last whorl axially deflected; two deep and short longitudinal furrows present. Aperture triangular with sinulus; peristome continuous, thickened, expanded, and reflected. Apertural dentition with one large and strong parietal, nearly adjoined small second parietal lamella; adjoined at right angles, one small upper palatal, one strong palatal, one strong basal, and bifid columellar lamella. Columellar lamella is sometimes absent. Umbilicus narrow (Fig.
This species has been widely recorded from India to Bhutan and Myanmar (
All the specimens of P. theobaldi (Fig.
Haploptychius
von Möllendorff in Kobelt, 1906: 127.
Odontartemon (Haploptychius)
– Thiele 1931: 730.
Oophana (Haploptychius)
–
Streptaxis sinensis Gould, 1859, by original designation.
Shell oblique-heliciform to ovate and last whorl deflected. Penultimate whorl round to bluntly angular and extended beyond last whorl. Apertural dentition includes only one parietal lamella. Genitalia with penial sheath thin to thick and extending ~ 1/2 to entire penis length. Penial hooks dense, slightly expanded at base, tips pointed, located on low to high conical papillae and vaginal hooks absent.
Haploptychius is almost identical with Carinartemis in having a deflected last whorl, extended penultimate whorl, and bearing a single parietal lamella. However, Haploptychius can be recognized by its oblique-ovate shell and rounded to angular penultimate whorl, while Carinartemis possesses an oblique-heliciform shell with sharply keeled penultimate whorl. In genitalia, Haploptychius has long and slender penial hooks, without vaginal hooks, while Carinartemis possesses shorter and blunt penial hooks, and sometimes transparent vaginal hooks may be present (
A recent molecular phylogeny revealed that Haploptychius is polyphyletic, and the traditional genus concept using shell shape and apertural dentition seems unreliable (
Currently, the genus Haploptychius is comprised of about 40 nominal species distributed from India to Indochina, southern and central China, and Sulawesi of Indonesia (
Helix bombax
Benson, 1859b: 186. Type locality: Moulmein, necnon and Phie Than in provincia Tenasserim [Mawlamyine, Mon State and Payathonzu, Kayin State, Myanmar].
Streptaxis bombax
–
Haploptychius bombax
–
Syntype
UMZC I.102470 (3 shells; Fig.
Haploptychius bombax can be differentiated from H. burmanicus by having a large oblique-ovate shell, without sinulus, and larger or wider last whorl. In contrast, H. burmanicus possesses a small sub-oblique heliciform shell, wide sinulus, and compressed last whorl. Compared with H. pellucens (Pfeiffer, 1863) from Laos, H. bombax differs by having strong radial ridges, convex spire, and narrow umbilicus, while H. pellucens exhibits a nearly smooth surface, more ovate shape, elevated spire, and umbilicus widely open.
Shell oblique-ovate, white, and translucent; whorls 5½–7; spire convex with distinct suture. Shell surface glossy with fine transverse ridges that diminish below periphery of penultimate whorl. Embryonic shell ~ 2½ whorls with smooth surface; following whorls regularly coiled. Shell periphery rounded; last whorl axially deflected. Aperture semi-ovate; peristome discontinuous, thickened, slightly expanded, and reflected. Apertural dentition with one strong parietal lamella. Umbilicus open and deep (Fig.
Haploptychius bombax is only known from the type locality in southeastern Myanmar (
The original description mentioned only 5½ whorls, but the museum specimen (Fig.
Streptaxis blanfordi
Theobald, 1864: 245. Type locality: Montibus Arakanensibus provincia Pegu [Arakan Mountains in Bago Region, Myanmar].
Streptaxis birmanica
Blanford, (in MSS.) Theobald, 1864: 245, 246 (in part). Type locality: Pegu [Bago Region, Myanmar].
Streptaxis blanfordianus
Streptaxis birmanica
–
Streptaxis blanfordi var. – Godwin-Austen 1895: 443.
Haploptychius blanfordianus
–
Haploptychius blanfordi
–
Streptaxis blanfordi
–
Streptaxis birmanicus
[sic] –
Syntype
A–C Haploptychius blanfordi A syntype
Haploptychius fischeri (Morlet, 1887) almost shares the same shell form as H. blanfordi, but the latter possesses a more depressed shell, penultimate whorl more bulging, aperture wider, longer and subquadrangular shape.
Shell oblique-heliciform, white, and translucent; whorls 6; spire convex with distinct suture. Shell surface glossy with fine transverse ridges that diminish below periphery. Embryonic shell ~ 2½ whorls with smooth surface; following whorls regularly coiled. Shell periphery rounded; last whorl axially deflected. Aperture semi-ovate; peristome discontinuous, thickened, expanded, and reflected. Apertural dentition with one strong parietal and small palatal lamellae. Umbilicus open and deep (Fig.
This species has been recorded with a wide distribution range from Arakan [Rakhine State], Pegu [Bago Region], and Shan State in Myanmar. However, the record from Cocos Islands in the southern Indian Ocean by
The taxonomic status of this species is still ambiguous because it is identical in shell morphology to Streptaxis birmanica.
The original spelling of the species was blanfordi, which was intentionally modified to blanfordianus by
Streptaxis burmanica
Streptaxis burmanicus
[sic] –
Haploptychius burmanicus
–
Possible syntype
Shell oblique-heliciform, white, and translucent; whorls 6; spire convex with distinct suture. Shell surface glossy with fine transverse ridges that diminish below periphery. Embryonic shell ~ 2½ whorls with smooth surface; following whorls regularly coiled. Shell periphery rounded; last whorl axially deflected. Aperture semi-ovate; peristome continuous; sometimes discontinuous, thin, expanded, and slightly reflected. Apertural dentition with one strong parietal lamella. Umbilicus open and deep (Fig.
Haploptychius burmanicus is still known only from the type locality in southern Myanmar (
This species highly resembles H. blanfordi in shell form, but H. burmanicus is more globosely heliciform, with a higher spire and only one parietal lamella. Without anatomical information, the generic placement of this species is still tentative, and we retain this as
Streptaxis solidulus
Stoliczka, 1871: 166, pl. 7, fig. 10. Type locality: Moulmein, Tenasserim [Mawlamyine District, Mon State, Myanmar].
Haploptychius solidulus
–
Moulmein:
Among the Haploptychius species from Myanmar, this species is distinctly large with an oblique-ovate shell, and less deflected last whorl. Haploptychius solidulus has almost the same shell form as Oophana mouhoti. However, it differs from O. mouhoti by having somewhat enlarged last whorl, more deflected last whorl, and a conical spire with only one parietal lamella. In contrast, O. mouhoti shows a depressed and obtuse conical spire, with one parietal and small basal lamellae.
Shell oblique-ovate, white, and opaque; whorls 6½–7; spire elevated conical with distinct suture. Shell surface glossy with fine transverse ridges that diminish below periphery. Embryonic shell ~ 2½ whorls with smooth surface; following whorls regularly coiled. Shell periphery rounded; last whorl axially deflected. Aperture semi-ovate; peristome discontinuous, thickened, expanded, and slightly reflected. Apertural dentition with one strong parietal lamella. Umbilicus open and deep (Fig.
This species appears to be restricted to limestone karsts and is only recorded from southern Myanmar.
Streptaxis thebawi
Godwin-Austin, 1888: 243. Type locality: Pingoung, Shan Hills [Pinlaung Township, Taunggyi District, Shan State, Myanmar].
Haploptychius thebawi
–
Limestone hills (Apache Cement Factory), Pyinyaung Village, Thazi Township, Meiktila District, Mandalay Region, Myanmar (20°49'39.1"N, 96°23'35.1"E):
Haploptychius thebawi is similar to H. solidulus in having a high conical spire and globosely ovate shell. The former species can be discriminated by its smoother shell surface and narrower aperture, more rounded and extended penultimate whorl, and less inflated last whorl. Additionally, H. thebawi resembles H. porrectus (Pfeiffer, 1863) from Laos in having strong radial ridges, conical spire, and an inflated and deflected last whorl, whereas H. thebawi exhibits a larger shell, less depressed and deflected last whorl, fine radial ridges, and higher spire.
Shell oblique-heliciform, white and translucent; whorls 5½–6½; spire conical with distinct suture. Shell surface glossy with transverse ridges that diminish below periphery. Embryonic shell ~ 2½ whorls with smooth surface; following whorls regularly coiled. Shell periphery rounded; last whorl axially deflected. Aperture subcircular; peristome discontinuous, thickened, expanded, and slightly reflected. Apertural dentition with one strong parietal lamella. Umbilicus open and deep (Fig.
This species occurs in central-eastern Myanmar, based on the type locality and two localities in Shan State, one locality in Mandalay Region, and it is relatively low in population density.
Originally, H. thebawi was described based on specimens from Pingoung, Shan Hills, which is probably now referred to as Pinlaung Township, Taunggyi District, Shan State. Unfortunately, the type specimens of H. thebawi could not be located in the
Among three populations of H. thebawi (Table
Holotype
This new species was found from the limestone karsts near Lampane Village, Tanintharyi Region, Myanmar (11°40'18.1"N, 99°13'30.1"E).
The specific name tenasserimicus refers to the type locality of this new species located on the Tenasserim Mountain Range, which forms the backbone of Indochina.
This species is distinguishable by its small size, angular penultimate whorl, low convex spire, and aperture that elongates and grows almost horizontally. Haploptychius tenasserimicus sp. nov. differs from H. burmanicus and H. blanfordi species by having oblique-ovate shells, prominent transverse ridges, higher spire, rounded penultimate whorl, and less deflected last whorl. This new species also differs from H. blaisei (Dautzenberg & Fischer, 1905) from Laos and Vietnam by having a relatively smaller shell (width ~ 8 mm), nearly flattened spire, angular penultimate whorl and rounded last whorl. In contrast, H. blaisei possesses a relatively larger shell (width ~ 10 mm), higher spire, rounded penultimate whorl, and compressed last whorl. In addition, H. tenasserimicus sp. nov. can be distinguished from H. dorri (Dautzenberg, 1894) from Vietnam (see
Shell sub-oblique heliciform, white and translucent; whorls 6; spire low convex with distinct suture. Shell surface glossy with fine transverse ridges that diminish below periphery; varices present. Embryonic shell ~ 2½ whorls with smooth surface; following whorls regularly coiled. Shell periphery angular; last whorl axially deflected. Aperture semi-ovate; peristome discontinuous, expanded and slightly reflected. Apertural dentition with one parietal lamella. Umbilicus open and shallow (Fig.
This species was only collected from the type locality; limestone hills in primary forest in the Tanintharyi Region, Myanmar.
The genitalia information is not known.
Holotype
A, B Haploptychius heliakosus sp. nov. A paratype
Bardai Mountain, Hpa-an Township, Hpa-an District, Kayin State, Myanmar (16°59'50"N, 97°41'48"E).
Kyonknow Cave, Hpa-an Township, Hpa-an District, Kayin State, Myanmar (17°01'00.1"N, 97°41'42.1"E):
Haplotychius heliakosus sp. nov. differs from H. bombax by having a deeper suture, higher spire, rounded penultimate whorl, and subquadrangular aperture. In contrast, H. bombax possesses a relatively shallower suture, lower spire, angular penultimate whorl, and semi-ovate aperture. Haplotychius heliakosus sp. nov. also differs from H. burmanicus and H. blanfordi by having an oblique ovate shell, higher spire, and less axially deflected last whorl. In contrast, the two latter species exhibit a depressed heliciform shell and lower spire, and more axially deflected last whorl. Although H. heliakosus sp. nov. has a shell similar to H. pellucens from Laos, this new species has a less axially reflected last whorl, subquadrangular aperture, and more ridges on the shell surface. Additionally, the genitalia of H. heliakosus sp. nov. has a thickened penial sheath covering almost the entire penis, and short and stout penial hooks on papillae, while H. pellucens has a thin penial sheath covering ~ 1/2 of the penis, and long and slender penial hooks without papillae. This new species differs from C. exacutus (Gould, 1856) by having penial sheath retractor muscle originating at atrium, vas deferens passing through a short section of thin penial sheath before extending ~ 1/3 of the penial sheath length to the curved portion, shorter free oviduct, seminal vesicle ca. twice the length from talon to branching point of seminal vesicle, thickened atrial folds with sparse atrial pores, and stout distal penial hooks.
Shell oblique-ovate, white, and translucent; whorls 7–7½; spire low conical with distinct suture. Shell surface glossy with transverse ridge, nearly smooth with few transverse ridges near peristome. Embryonic shell large, ~ 2½ whorls with smooth surface; following whorls regularly coiled. Penultimate whorl rounded; last whorl axially deflected. Aperture subquadrangular; peristome discontinuous, thickened, expanded, and slightly reflected. Apertural dentition with one strong parietal lamella and sometimes with small second parietal lamella adjoined at a right angle. Umbilicus open and deep (Fig.
Genital organs. Atrium (at) short. Penis (p) very thin, and long tube. Penial sheath (ps) muscularly enlarged, very thickened, and extending entire penis length; penial sheath retractor muscle (psr) thin, originating at atrium, and inserting distally on penial sheath (Fig.
Internal wall of atrium generally smooth with transverse thickened atrial folds with sparse atrial pores (Fig.
Internal sculpture of genitalia of Haploptychius heliakosus sp. nov. paratype
Internal wall of atrium generally smooth with sparse atrial pores (Fig.
Vagina very short, stout, and ~ 1/10 of penis length. Gametolytic duct (gd) a long tube extending as far as albumin gland; gametolytic sac (gs) ovate. Proximal free oviduct (fo) enlarged, tapering to a smaller tube in the middle part, then enlarged distally. Oviduct (ov) enlarged and folded; prostate gland inconspicuous and bound to oviduct. Talon (ta) small, short, and club shaped. Hermaphroditic duct (hd) bearing long seminal vesicle (sv) of about twice the length from talon to branching point of seminal vesicle (Fig.
Vaginal wall with longitudinal vaginal folds (Fig.
Radula. Each row consists of ~ 35 teeth with formula (17)–1–(17). Central tooth very small with pointed cusp. Lateral and marginal teeth undifferentiated, lanceolate, unicuspid, and lanceolate. Latero-marginal teeth gradually reduced in size, with outermost teeth much smaller and shorter than inner teeth (Fig.
The specific name heliakosus is derived from the Greek word heliakos meaning of the sun. It honors our colleague, Dr. Arthit Pholyotha, who collected the specimens and took the photos of the living snails used in this study. His first name Arthit means the Sun.
This new species is currently known from two localities in the limestone karsts near Salween (Thanlwin) Basin, Kayin State, southeastern Myanmar.
Shell variations of H. heliakosus sp. nov. were found between two populations. Specimens from the Kyonknow population (Fig.
Holotype
Limestone outcrops at Waiponla Hill, Hpa-an Township, Hpa-an District, Kayin State, Myanmar (16°56'7.4"N, 97°42'56.8"E).
Taung Lay Cave, Hpa-an Township, Hpa-an District, Kayin State, Myanmar (17°11'40.3"N, 97°37'47.0"E):
Haploptychius karenorum sp. nov. can be differentiated from H. heliakosus sp. nov. by having a convex spire, penultimate whorl angular and extended well beyond the diameter of the last whorl, and more axially deflected last whorl. In contrast, H. heliakosus sp. nov. possesses an elevated spire, penultimate whorl rounded, less extended beyond the diameter of the last whorl, and less axially deflected last whorl. This new species differs from H. bombax by having an angular penultimate whorl, more axially deflected last whorl, subcircular aperture, and broadly expanded lip. In comparison, H. bombax has a rounded penultimate whorl, less axially deflected last whorl, semi-ovate aperture, with thickened and slightly expanded lip. For further comparison, H. karenorum sp. nov. differs from H. burmanicus, H. blanfordi, and H. thebawi in having a more axially deflected last whorl, lower spire, penultimate whorl angular and strongly extended beyond the diameter of the last whorl, and without sinulus. The three latter species have an elevated spire, penultimate whorl rounded and slightly extended beyond the diameter of the last whorl, and less axially deflected last whorl.
Shell oblique-ovate, solid and translucent; whorls 6–7½; spire depressed convex and with distinct suture. Embryonic shell ~ 2½ whorls with smooth surface; following whorls growing regularly and last whorl intermediately expanded. Shell surface has moderately strong radial ridges that diminish below periphery of last whorl and around umbilicus. Penultimate whorl bluntly angular and extended beyond last whorl. Last whorl compressed to flattened, axially deflected from columellar axis. Aperture subcircular; peristome thickened, expanded, and slightly reflected. Apertural dentition with one strong parietal lamella. Umbilicus widely open and deep (Fig.
The specific name karenorum refers to the Karen people, the major ethnicity in Kayin State, Myanmar.
This species is known from two localities in the limestone karts of Kayin State, southern Myanmar.
Comparing populations from the two localities, shells of H. karenorum sp. nov. from the Taung Lay population (Fig.
Carinartemis
Siriboon & Panha in
Carinartemis vesperus Siriboon & Panha, 2014 by original designation.
Shell obliquely heliciform and with conical spire. Penultimate whorl keeled and extended beyond the diameter of the last whorl. Last whorl rounded to shouldered and strongly axially deflected. Aperture semi-ovate to subcircular; apertural dentition with or without one or two parietal lamellae. Genitalia with thin to thick penial sheath that covers entire penis length; penial hooks and vaginal hooks may be present.
The genus is comprised of two endemic species occurring in limestone outcrops in western Thailand. A recent phylogenetic study revealed that the previously recognized Haploptychius petitii (Gould, 1844) and Indoartemon medius Siriboon & Panha, 2014 are clustered with members of the Carinartemis (see
Streptaxis petitii Gould, 1844: 456, 457, pl. 24, fig. 7. Type locality: Tavoy [Dawei District, Tanintharyi Region, Myanmar].
Streptaxis petiti
[sic] –
Haploptychius petiti
[sic] –
Haploptychius petitii
–
Syntype
A, B Carinartemis petitii A syntype
Carinartemis petitii can be distinguished from C. sankeyi (Benson, 1859) by having a fine transverse ridge on the upper periphery, penultimate whorl keeled and little extended beyond the diameter of last whorl, and a subcircular aperture. In addition, C. petitii differs from I. medius from Thailand by having a more axially deflected last whorl, and only one parietal lamella present, while I. medius has a less axially deflected last whorl, and with one additional small palatal lamella. Carinartemis petitii is superficially similar to H. blaisei but it has an elevated spire, keeled penultimate whorl, subcircular aperture, and thicker lip.
Shell oblique-heliciform, white, and translucent; whorls 6½–7; spire conical with distinct suture. Shell surface glossy with fine transverse ridges, nearly smooth with a few transverse ridges near peristome. Embryonic shell ~ 2½ whorls with smooth surface; following whorls regularly coiled. Shell periphery keeled nearly the entire penultimate whorl; last whorl axially deflected. Aperture subcircular; peristome discontinuous, thickened, expanded, and reflected. Apertural dentition with one strong parietal lamella. Umbilicus open and deep (Fig.
This species is known from the type locality in Myanmar (
No new specimens were collected in this survey. However, the syntype (Fig.
Streptaxis exacutus Gould, 1856: 13. Type locality: Burma [Myanmar].
Streptaxis exacuta
[sic] –
Streptaxis exacutus
–
Haploptychius exacutus
–
Moulmein:
Carinartemis exacutus is superficially similar to C. sankeyi, C. vesperus Siriboon & Panha, 2014, and C. striatus Siriboon & Panha, 2014 from western Thailand, but it has a larger shell, convex spire, immediately expanded penultimate whorl, semi-ovate aperture, two parietal lamellae, very thickened penial sheath, vas deferens passes through penial sheath, curved portion of vas deferens with very thin connective tissue, and hooks located on irregular trapezoidal penial papillae separated by longitudinal folds. In comparison, C. sankeyi, C. vesperus, and C. striatus have an elevated spire, regularly expanded penultimate whorl, but C. sankeyi has fine transverse ridges on the entire shell, subquadrangular aperture, one parietal lamella, slender atrium, thin penial sheath, vas deferens does not pass through a penial sheath, curved portion of vas deferens is without connective tissue, proximal penial hook located on laterally-flattened penial papillae, and distal penial hooks located on laterally compressed penial papillae separated by reticulated folds. In contrast, C. vesperus has a subcircular aperture, lacks parietal lamellae, has a less axially deflected last whorl, vas deferens passes through the penial sheath, curved portion of vas deferens is without connective tissue, and penial papillae absent. Meanwhile, C. striatus has strong transverse ridges over the entire shell, a semi-ovate aperture, one parietal lamella, vas deferens is attached to the distal end of the penial sheath with very thin connective tissue, and hooks are located on papillae without connected longitudinal folds.
Shell oblique-heliciform, white, and translucent; whorls 6–6½; spire convex with distinct suture. Shell surface glossy with fine transverse ridges, nearly smooth with few transverse ridges near peristome; varices present. Embryonic shell ~ 2½ whorls with smooth surface; following whorls intermediately coiled. Shell periphery wide and sharply keeled along nearly the entire penultimate whorl; last whorl axially deflected. Aperture semi-ovate; peristome discontinuous, thickened, expanded, and slightly reflected. Apertural dentition with one strong parietal lamella and sometimes with a second parietal lamella adjoined at a right angle. Umbilicus open and deep (Figs
Genital organs. Atrium (at) short. Penis (p) a very thin, and long tube. Penial sheath (ps) muscularly enlarged, very thickened and extending entire length of penis; penial sheath retractor muscle (psr) thin, originating near genital orifice, attached to atrium with short and thin connective tissue, and inserting distally on penial sheath (Fig.
Internal wall of atrium generally smooth with sparse atrial pores (Fig.
Vagina (v) very short and ~ 1/12 of penis length. Gametolytic duct (gd) a long tube extending as far as albumin gland; gametolytic sac (gs) ovate. Proximal free oviduct (fo) enlarged then tapering to smaller diameter distally. Oviduct (ov) enlarged and folded; prostate gland inconspicuous and bound to oviduct. Talon (ta) small, short and club shaped. Hermaphroditic duct (hd) bearing long seminal vesicle (sv) ~ 1/2 the length from talon to branching point of seminal vesicle (Fig.
Vaginal wall with longitudinal oblique vaginal folds, folds with nearly smooth surface and vaginal hook absent (Fig.
Radula. Each row consists of 41–45 teeth with formula (22–20)–1–(20–22). Central tooth is very small with pointed cusp. Lateral and marginal teeth undifferentiated, lanceolate, unicuspid, and lanceolate. Latero-marginal teeth gradually reduced in size, with outermost teeth much smaller and shorter than inner teeth (Fig.
This species was collected from five limestone hills in Kayin State, southern Myanmar, in this survey.
This species appears at a high abundance among the limestone karsts in Hpa-an, Kayin State. All the specimens examined from the populations from Lun Nga Mountain and Bayin Nyi Cave have a very small to indistinct upper parietal lamella, and some specimens from Bayin Nyi Cave have strong transverse ridges on almost the entire whorl. Moreover, the Lun Nga Mountain population have a last whorl that is more extended anteriorly and an elongated semi-ovate aperture (Fig.
Although the type locality was listed as ‘Burma’ [Myanmar], all the known records and specimens examined in this study were collected from Kayin State. Therefore, the precise type locality of this species is probably southwestern Myanmar in Mon State and Kayin State.
Streptaxis sankeyi
Benson, 1859a: 472. Type locality: Moulmein [Mawlamyine Township, Mon State, Myanmar].
Streptaxis sankeyanus
Stoliczka, 1871: 167, 168, pl. 7, fig. 14 (unjustified emendation).
Streptaxis hanleyanus
Stoliczka, 1871: 168, 169, pl. 7, fig. 15. Type locality: Prope Moulmein, ad flumen Attaran [Attaran River, Mawlamyine, Mon State, Myanmar].
Haploptychius sankeyi
–
Oophana hanleyana
–
Syntype
UMZC I.102740 (6 shells; Fig.
Carinartemis sankeyi A specimen
Carinartemis sankeyi is superficially similar to C. vesperus and C. striatus in having a subquadrangular aperture, and less expanded and continuous peristome, slender atrium, vas deferens does not pass through a penial sheath, proximal penial hooks located on laterally flattened penial papillae, and distal penial hooks located on laterally compressed penial papillae separated by reticulated folds. In contrast, the shell of C. vesperus has fine transverse ridges (nearly smooth) with few transverse ridges near peristome, varices absent, periphery more extended beyond the diameter of last whorl, lacking parietal lamella, and penial papillae absent. Meanwhile, C. striatus has vas deferens attached to the distal end of penial sheath with very thin connective tissue, and hooks located on papillae without connected longitudinal folds.
Shell oblique-heliciform, white, translucent; whorls 6–7; spire conical with distinct suture. Shell surface glossy with fine transverse ridge across the entire shell; varices present. Embryonic shell ~ 2½ whorls with smooth surface; following whorls regularly coiled. Shell periphery wide and sharply keeled around nearly the entire penultimate whorl; last whorl axially deflected. Aperture subquadrangular; peristome continuous, thickened, expanded, and reflected. Apertural dentition with one strong parietal lamella. Umbilicus open and deep (Figs
Genital organs. Atrium (at) short, thin and slender. Penis (p) very thin and long. Penial sheath (ps) thin and extending nearly entire length of penis; penial sheath retractor muscle (psr) thin, originating near genital orifice and attached to atrium with short and thin connective tissue, and inserting distally on penial sheath (Fig.
Internal sculpture of genitalia of Carinartemis exacutus, specimen
Internal wall of atrium generally smooth with sparse atrial pores (Fig.
Internal sculpture of genitalia of Carinartemis sankeyi, specimen
Vagina (v) short, stout and ~ 1/5 of penis length. Gametolytic duct (gd) a long tube extending as far as albumin gland; gametolytic sac (gs) ovate. Proximal free oviduct (fo) enlarged then tapering to smaller diameter in middle section, and slightly enlarged distally. Oviduct (ov) enlarged and folded; prostate gland inconspicuous and bound to oviduct. Talon (ta) small, short and club shaped. Hermaphroditic duct (hd) bearing long seminal vesicle (sv) ca. the same length as from talon to branching point of seminal vesicle (Fig.
Vaginal wall generally smooth with vaginal pores, and vaginal hook absent (Fig.
This species occurs from three localities in Mon State, southern Myanmar and is likely to be endemic to this area.
Each row consists of 43–49 teeth with formula (21–24)–1–(21–24). Central tooth small with pointed cusp. Lateral and marginal teeth undifferentiated, unicuspid and lanceolate. Latero-marginal teeth gradually reduced in size, with outermost teeth much smaller and shorter than inner teeth (Fig.
Radula of specimens A Discartemon tonywhitteni, paratype
The original spelling of this nominal species was sankeyi, which was intentionally modified to sankeyanus by
Recently, the population collected from Dhammatat Cave showed a more rectangular aperture, slightly compact penultimate whorl, and larger parietal lamella (Fig.
This research presents all known Streptaxidae in Myanmar, comprising eighteen species belonging to five genera (Carinartemis, Discartemon, Haploptychius, Oophana, and Perrottetia), including fourteen formerly known species and four new species (Table
Comparative shell morphology of all recognized streptaxid species in Myanmar.
Species | Shell shape | Spire | Shell surface | Penultimate whorl | Last whorl | Apertural dentition (lamellae) |
---|---|---|---|---|---|---|
D. tonywhitteni | depressed heliciform | low-conical to convex | glossy with fine transverse ridges | flattened | angular (sometimes narrowly rounded) | one parietal, one palatal, one basal, one columellar, and one supracolumellar (sometimes with small upper palatal) |
D. paurodeviatus sp. nov. | globose heliciform | conical | glossy with fine transverse ridges | rounded, not extended beyond last whorl | rounded, little axially deflected | one parietal, one palatal, one basal, and one columellar (sometime with supracolumellar) |
O. elisa | oblique heliciform | convex | transverse ridges | angular, extended beyond last whorl | axially deflected | one parietal, one palatal, one basal, and one columellar (sometimes with supracolumellar) |
O. mouhoti | oblique ovate | elevated conical | glossy with fine transverse ridges | slightly angular, not extended beyond last whorl | axially deflected | one parietal, one upper palatal, one palatal, and one basal |
O. obtusus | oblique ovate | convex | glossy with fine transverse ridges | rounded to weakly angular and scarcely extended beyond last whorl | slightly axially deflected | one parietal, one palatal, and one columellar |
O. laevis | oblique heliciform | low convex | glossy with transverse ridges | rounded, not extended beyond last whorl | axially deflected | one parietal, and one basal, (columellar lamella present or absent) |
P. theobaldi | sub-oblique heliciform | convex | glossy with transverse ridges | rounded, not extended beyond last whorl | axially deflected | one parietal nearly adjoint with small second parietal, one upper palatal, one palatal, one basal, and one bifid columellar |
H. bombax | oblique ovate | convex | glossy with fine transverse ridges | rounded, slightly extended beyond last whorl | axially deflected | only one parietal lamella |
H. blanfordi | oblique heliciform | convex | glossy with fine transverse ridges | rounded, slightly extended beyond last whorl | axially deflected | one parietal (sometimes with small palatal) |
H. burmanicus | oblique heliciform | convex | glossy with fine transverse ridges | rounded, slightly extended beyond last whorl | axially deflected | one parietal |
H. solidulus | oblique ovate | elevated conical | glossy with fine transverse ridges | slightly angular, not extended beyond last whorl | axially deflected | one parietal |
H. thebawi | oblique heliciform | conical | glossy with transverse ridges | rounded, less extended beyond last whorl | axially deflected | one parietal |
H. tenasserimicus sp. nov. | sub-oblique heliciform | low convex | glossy with fine transverse ridges | angular, extended beyond last whorl | axially deflected | one parietal |
H. heliakosus sp. nov. | oblique ovate | low conical | glossy with transverse ridges | rounded, extended beyond last whorl | axially deflected | one parietal |
H. karenorum sp. nov. | depressed ovate | depressed-convex | moderately strong transverse ridges | bluntly angular, extended beyond last whorl | axially deflected | one parietal |
C. petitii | oblique heliciform | high to low conical | fine transverse ridges | subangular, slightly extended beyond last whorl | axially deflected | one parietal |
C. exacutus | oblique heliciform | convex | glossy with fine transverse ridges | sharply keel, extended beyond last whorl | axially deflected | one parietal (sometimes with second parietal) |
C. sankeyi | oblique heliciform | convex | glossy with fine transverse ridges | sharply keeled, extends beyond last whorl | axially deflected | only one parietal |
Most reported streptaxids in Myanmar occupy a narrow distribution, and some species were found in only a single area, such as one species of Perrottetia in Shan State, two species of Discartemon in the Tanintharyi Region, and two species of Carinartemis in Kayin and Mon States, which are adjacent regions. In contrast, Haploptychius has a wide distribution, ranging from central-northeastern to southern Myanmar, including previously recorded localities, such as Rakhine State and the Bago Region (
Herein, all previously documented species of Oophana have been redescribed, based on original descriptions compared with historical museum specimens except for O. mouhoti, a new record in Myanmar but based on only a single shell.
The most dominant genus, Haploptychius, are found mainly in Hpa-an, in the southern part of Myanmar. This genus also shows variability in its shell shape related to their geographic distribution. For example, snails from the (i) Kayin State have more globosely ovate shells and a larger size, while those from (ii) Tanintharyi Region have depressed shells, and those from (iii) Mandalay Region and Shan State have smaller, ovate shells and most bear only one parietal lamella. Exceptionally, H. heliakosus sp. nov. from the type population has an extra small tubercle next to the parietal lamella, and similarly, H. blanfordi has a small palatal lamella. While the male reproductive organ of the Haploptychius species in Laos shows a relatively thin penial sheath with slender, elongate penial hooks (
So far, five species in the genus Carinartemis have been recorded from Thailand and Myanmar (
The senior author is grateful to all members of the Animal Systematics Research Unit (ASRU) members, Chulalongkorn University for their kind help during field trips in Myanmar. The authors are indebted to AJ Baldinger (