Research Article |
Corresponding author: Somsak Panha ( somsak.pan@chula.ac.th ) Academic editor: Thierry Backeljau
© 2023 Nem Sian Man, Ngwe Lwin, 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:
Man NS, Lwin N, Sutcharit C, Panha S (2023) Further notes on the taxonomy of the land snail family Clausiliidae Gray, 1855 (Stylommatophora, Helicina) from Myanmar with description of two new species. ZooKeys 1160: 1-59. https://doi.org/10.3897/zookeys.1160.98022
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This study presents a complete species list of the door snails inhabiting Myanmar, updated to now include 33 taxa, and provides taxonomic notes together with a re-description of the shell, radula, and genitalia for 13 species and subspecies, including Oospira philippiana, the type species of the genus Oospira. The snails previously treated as subspecies or synonyms of Oospira gracilior and Oospira magna are reclassified and recognized as distinct species. The lectotype of Oospira insignis has been clarified and an illustration of the original type specimen provided. A long-overlooked species, Oospira andersoniana, has been collected and redescribed herein. Two new species from the limestone karsts in the Salween River Basin are introduced: Oospira luneainopsis Man & Panha, sp. nov. and Oospira zediopsis Man & Panha, sp. nov. A synoptic view of all clausiliid taxa known from Myanmar is presented along with taxonomic information and distributional records. Photographs of the type materials for all taxa are provided for further comparison or, if unavailable, photographs of the examined specimens or the original figure from the literature.
Biodiversity, door snail, endemic, gastropod, limestone, systematics
Door snails are well-known land snails belonging to the family Clausiliidae Gray, 1855, and are easily recognized by their usually sinistral fusiform shell and their unique clausilial apparatus: clausilium, plicae and lamellae (
Only two of the seven subfamilies of Clausiliidae have diversified in Southeast Asia: Phaedusinae Wagner, 1922 and Garnieriinae Boettger, 1926 (
Knowledge of Myanmarese door snails was primarily reported during the colonial period in the 19th century by the pioneering western naturalists (see
Traditionally, shell morphology employs apomorphic characters for species recognition, including lamellae development, and the number and position of palatal plicae (i.e.,
Myanmar is actively promoting knowledge of its malacofauna, especially the material obtained under the framework of a joint project between the Forest Department of Myanmar, the Fauna and Flora International (FFI), and the Animal Systematics Research Unit (ASRU) of Chulalongkorn University, Thailand. This effort has already provided information regarding the distribution, habitat, and essential morphological characters (e.g., genitalia and radula) of the Myanmarese malacofauna, including the description of several new ariophantids and helicarionids taxa (
This study was conducted within the MoU (Letter No. 0092) framework between the Forest Department, Ministry of Natural Resources and Environmental Conservation and Forestry, Myanmar and FFI from 2015 to 2016. Specimens were collected throughout northern and southern Myanmar (Fig.
Shell measurements of clausiliid species examined in this study. The numbers listed with collection localities correspond to the map in Fig.
Species no., locality no., and |
Number of specimens | Ranges, mean ± S.D. in mm | SH/SW ratio | Number of whorls | |
---|---|---|---|---|---|
Shell height | Shell width | ||||
1. Phaedusa shanica | |||||
1. Pyinyaung Village, Meiktila, Mandalay (13032, 13033) | 46 | 16.0–18.0 16.88 ± 0.87 | 3.0–3.4 3.25 ± 0.13 | 5.0–5.5 5.22 ± 0.26 | 11–13½ |
2. Phaedusa burmanica | |||||
2. Myin Ma Hti, Kalaw, Shan (13034, 13035) | 2 | 24.0–25.3 24.76 ± 0.68 | 5.0–5.4 5.16 ± 0.20 | 4.68–4.9 4.79 ± 0.10 | 12, 13 |
3. Phaedusa bocki menglunanensis | |||||
3. Aik Kham Cave, Taunggyi, Shan (13036) | 3* | 22.8, 23.9, 24.0 | 4.3, 4.5, 5.0 | 4.8–5.3 5.13±0.29 | 12–13 |
4. Oospira philippiana | |||||
4. Saddan Cave, Mawlamyine, Mon (13037) | 10 | 21.6–23.0 22.22 ± 0.64 | 7.0–8.2 7.76 ± 0.45 | 2.8–3.1 2.86 ± 0.12 | 5–6 |
5. Kayon Cave, Mawlamyine, Mon (13038, 13039) | 21 | 21.0–22.6 21.96 ± 0.61 | 7.2–8.0 7.52 ± 0.30 | 2.8–3.0 2.92 ± 0.07 | 5–6 |
6. Pha Boang Cave, Mawlamyine Mon (13040¸ 13041) | 24 | 25.5–26.6 25.95 ± 0.47 | 7.9–8.2 8.02 ± 0.12 | 3.2–3.3 3.23 ± 0.03 | 6–6½ |
5. Oospira bulbus | |||||
7. Sanbel Cave, Mawlamyine, Mon (13042, 13043) | 18 | 19.39–19.78 19.56 ± 0.17 | 8.00–8.55 8.30±0.19 | 2.28–2.42 23.57±0.05 | 5–5½ |
6. Oospira ovata | |||||
8. Pathein Mountain, Mawlamyine, Mon (13044, 13045) | 26 | 16.8–18.4 17.60±0.59 | 6.7–7.1 6.92 ± 0.20 | 2.5–2.7 2.54 ± 0.08 | 5–5½ |
7. Oospira stoliczkana | |||||
9. Phra Cave, Tanintharyi (13046, 13047) | 5 | 21.6–25 23.47 ± 1.64 | 6.7–7.1 6.92 ± 0.17 | 3.1–3.6 3.39 ± 0.22 | 6–6½ |
8. Oospira gouldiana | |||||
10. Bardai Mountain, Hpa-an, Kayin (13048) | 25 | 24.8–29.0 26.10 ± 1.69 | 5.7–6.2 5.90 ± 0.21 | 4.1–4.8 4.42 ± 0.25 | 10–11 |
11. Kaw Ka Thaung, Hpa-an, Kayin (13049) | 23 | 25.8–27.8 26.81 ± 0.88 | 6–7 5.97 ± 0.32 | 4.3–4.9 4.50 ± 0.28 | 10–11 |
12. Lun Nga Mountain, Hpa-an, Kayin (13050) | 18 | 24.0–27.0 26.32 ± 1.41 | 5.7–6.5 6.11 ± 0.34 | 4.0–4.9 4.31 ± 0.27 | 11–12 |
13. Sadhdan Cave, Hpa-an, Kayin (13051) | 2* | 25.0, 29.0 | 5.4, 6.2 | 4.63–46.7 4.65±0.34 | 11, 11½ |
14. Taung Lay Cave, Hpa-an, Kayin (13052) | 30 | 28.1–29.2 28.50 ± 0.47 | 5.6–5.9 5.80 ± 0.14 | 4.77–5.21 4.91 ± 0.17 | 11½–12 |
15. Waiponla Mountain, Hpa-an, Kayin (13053, 13054) | 4* | 26.0–27.5 26.42 ±0.72 | 6.0–7.0 6.52±0.41 | 3.92–4.33 4.05±0.18 | 8–8½ |
16. Rathye Pyan Cave, Hpa-an, Kayin (13055) | 1* | 21.83 | 6.1 | 3.57 | 6 |
9. Oospira andersoniana | |||||
17. Phra Cave, Tanintharyi (13056, 13057) | 34 | 18.6–22.0 19.75 ± 1.26 | 4.1–4.4 4.28 ± 0.13 | 4.3–5.0 4.60 ± 0.22 | 9–10 |
10. Oospira magna | |||||
18. Bayin Nyi Cave, Hpa-an, Kayin (13058, 13059) | 4 | 21.8–26.3 24.68 ± 1.76 | 5.3–5.5 5.38 ± 0.08 | 4.1–4.7 4.58 ± 0.27 | 10–11 |
11. Oospira shanensis | |||||
19. Nanthe Cave, Kalaw, Shan (13060, 13061) | 9 | 24.5–26.0 25.63 ± 1.00 | 5.9–0.6 5.93 ± 0.60 | 4.0–4.6 4.34 ± 0.31 | 12½–13 |
12. Oospira luneainopsis sp. nov. | |||||
20. Zwekabin Mountain, Hpa-an, Kayin (13062, 13063) | 8 | 18.7–21.6 20.34 ± 1.34 | 5.6–6.0 5.72 ± 0.16 | 3.3–3.9 3.50 ± 0.23 | 7–8 |
13. Oospira zediopsis sp. nov. | |||||
21. Weibyan Cave, Hpa-an, Kayin (13064, 13065) | 50 | 22.4–26.8 24.98 ± 1.43 | 5.7–6.8 6.25 ± 0.38 | 3.8–4.2 4.00 ± 0.14 | 10–11 |
Shell dimensions (height and width), whorl count, coloration and sculpture were assessed from intact adult shells. The parietal wall of the last whorl of one to three shells was removed to observe the shape, size, thickness and numbers of plicae and lamellae, and clausilium morphology. The terminology used for the clausilial apparatus and genitalia in this description is modified from
Clausilial apparatus terminology, with Oospira philippiana as a representative species A apertural, lateral and dorsal views from left to right, respectively, showing the lamellae B inside view of last whorl showing principalis and palatal plicae C front (left) and back (right) views of clausilium plate. Color indicates each lamella character.
Two nominal species names described as new to science in this work are attributed to the first and last authors (Man and Panha). Thus, a complete citation of the authorship is “Man and Panha in Man et al.”.
at atrium;
bb bursa (of bursa copulatrix);
db diverticulum (of bursa copulatrix);
dpb distal part of pedunculus (of bursa copulatrix);
ep epiphallus;
fo free oviduct;
p penis;
ppb proximal part of pedunculus (of bursa copulatrix);
pr penial retractor muscle;
v vagina;
vd vas deferens.
JG-C Jozef Grego collection, Banska Bystrica, Slovakia;
Subfamily Phaedusinae Wagner, 1922
Clausilia (Phaedusa)
Adams & Adams, 1855: 184.
Phaedusa
–Thiele, 1931: 530.
Clausilia corticina Pfeiffer, 1842, by subsequent designation of Martens in
Shell fusiform, more or less turreted, spire attenuated and shell surface with fine wavy to oblique striations. Palatal plicae short mostly, middle plicae weak to developed and 3 to 7 in number. Superior lamella low, connected to or separated from spiralis, and distinct at transition to spiralis. Inferior lamella spirally ascending and ending close to superior lamella from aperture view. Subcolumellaris visible or invisible in frontal view. Clausilium plate lateral side, rounded and broad.
Animal covered with reticulated, dark gray skin; tentacles short; body and tail with paler color on lateral margin of foot; foot moderately elongated, posteriorly obtusely pointed.
In the most recent generic classifications and species accounts by
Clausilia (Pseudonenia) shanica
Boettger & Ponsonby in
Clausilia
[Phaedusa (Pseudonenia)] shanica–
Phaedusa (Phaedusa) shanica
–
Phaedusa shanica
–
Limestone hills (Apache Cement Factory), Pyinyaung Village, Meiktila District, Mandalay Region, Myanmar (20°49'39.1"N, 96°23'35.1"E):
Living snails A Phaedusa shanica from Pyinyaung Village, Mandalay Region (SH ~ 14 mm) B Oospira philippiana from Kayon Cave, Mon State (SH ~ 22 mm) C Oospira bulbus from Sanbel Cave, Mon State (SH ~ 19 mm) D Oospira ovata from Pathein Mountain, Mon State (SH ~ 16 mm) E Oospira gouldiana from Kaw Ka Thuang Cave, Kayin State (SH ~ 26 mm) F Oospira shanensis from Nanthe Cave, Shan State (SH ~ 25 mm).
Shell and clausilial apparatus of A, B Phaedusa shanica, specimen
Shell fusiform, turreted, translucent, and pale yellowish brown; spire acute. Shell surface with thin and dense oblique striations; suture distinct. Whorls 11–13½, little convex, regularly growing and attenuated to apex, last whorl somewhat compressed. Aperture obliquely rounded to pear-shaped, basis rounded and narrowing towards parietal sinus; peristome slightly protruded, thickened, and expanded. Superior lamella low, continuous with spiralis, and very low at transition to spiralis to almost separated. Inferior lamella spirally ascending, close to superior lamella and ending at peristome. Subcolumellaris emerged and only visible in oblique view. Principalis running along lateral-dorsal side and anterior end visible through oblique apertural view. Palatal plicae lateral, three: first plica strong and longest; second plica very weak and close to first plica; third plica oblique from subcolumellaris and sometimes almost connected to second plica. Palatal plicae not visible without cracking shell. Clausilium plate lateral side, broad, rounded and slightly thickened at tip.
Comparison of shell characters of all species from Myanmar examined in this study.
Species | Inferior lamella | Transition from superior to spiralis lamella | Subcolumellaris in oblique view | Palatal plicae number/ positions | Clausilium position / shape | Spire |
---|---|---|---|---|---|---|
P. shanica | spirally ascending | connect to almost separate | visible | 3/ 2nd weakest and lateral | lateral/ broad and round | regularly attenuated |
P. burmanica | spirally ascending | connect or separate | visible | 5/ 3rd and 4th weakest and lateral | lateral/ broad, round and with hook | regularly attenuated |
P. bocki menglunanensis | spirally ascending | connect / low at transition to spiralis | visible | 4–5/ reduced towards anterior and lateral | lateral/ broad, round and with hook | regularly attenuated |
O. philippiana | steeply ascending | connected / distinctly low at transition to spiralis | visible | 7–9/ reduced towards anterior and lateral | lateral/ slightly broad | blunt and regularly attenuated |
O. bulbus | steeply ascending | connected / distinctly low at transition to spiralis | invisible | 5/ nearly equal, reduced towards anterior and lateral | lateral/ narrow | round and rapidly grow |
O. ovata | steeply ascending | connected / distinctly low at transition to spiralis | visible | 6–7/ gradually reduced towards anterior and lateral | lateral/ narrow | blunt and rapidly grow |
O. stoliczkana | steeply ascending | connected / distinctly low at transition to spiralis | visible | 8–10/ gradually reduced towards anterior and lateral | lateral/ slightly broad | blunt and regularly attenuated |
O. gouldiana | steeply ascending | connected / slightly low at transition to spiralis | invisible | 5/ 1st and 4th or 5th longest, parallelly, or irregularly oblique, and lateral | lateral/ narrow | regularly attenuated, 3 to 4 apical whorls white |
O. andersoniana | steeply ascending | connected / indistinct at transition to spiralis | invisible | 3–5 / 3rd longest, parallelly oblique, and lateral | lateral/ narrow | regularly attenuated |
O. magna | steeply ascending | connected / indistinct at transition to spiralis | invisible | 4–6 / 4th longest, parallelly oblique, and ventral-lateral (almost horizontal) | ventral/ narrow | regularly attenuated, 3 to 4 apical whorls white |
O. shanensis | steeply ascending | connected / indistinct at transition to spiralis | visible | 5 / 4th longest and curved, parallel, and ventral-lateral (almost horizontal) | lateral/ broad, round and with hook | regularly attenuated |
O. luneainopsis sp. nov. | steeply ascending | connected / slightly low at transition to spiralis | invisible | 4 / 4th longest, parallelly oblique, and lateral | lateral/ narrow, slightly pointed at tip | blunt and regularly attenuated |
O. zediopsis sp. nov. | steeply ascending | connected / slightly low at transition to spiralis | invisible | 4–5 / 4th longest, parallelly oblique, and lateral | lateral/ narrow | regularly attenuated, 4 to 5 apical whorls white |
Comparison of genital characters of all species from Myanmar examined in this study.
Species | Penis / epiphallus | Internal sculpture of penis | Internal sculpture of epiphallus | Distal and proximal lengths of pedunculus |
---|---|---|---|---|
P. shanica | muscular, large / ca. same diameter with penis | smooth surface of longitudinal folds | papillae arranged in oblique rows | distal longer than proximal |
P. burmanica | muscular, large / ca. same diameter with penis | wavy surface of longitudinal folds | wavy longitudinal folds and papillae arranged in oblique rows | distal longer than proximal |
O. philippiana | muscular, large / narrower than penis | chevron-shaped and smooth surface of longitudinal folds | elevated papillae arranged in oblique rows | distal shorter than proximal |
O. bulbus | muscular, large / narrower than penis | chevron-shaped and little wavy surface of longitudinal folds | elevated papillae arranged in oblique rows | distal ca. same as proximal |
O. ovata | muscular, large / narrower than penis | V-shaped rows and smooth surface of longitudinal folds | rounded papillae arranged in oblique rows | distal longer than proximal |
O. stoliczkana | muscular, large / narrower than penis | nearly V-shaped and oblique smooth surface of longitudinal folds | elevated papillae arranged in nearly oblique rows | distal longer than proximal |
O. gouldiana | moderately muscular, slender / nearly same or narrower diameter than penis | smooth surface of longitudinal folds | irregular corrugated folds and papillae arranged in oblique rows | distal ca. same as proximal |
O. andersoniana | moderately muscular, slender / nearly same or narrower diameter than penis | smooth surface of longitudinal folds | scattered papillae arranged obliquely to irregularly spaced rows | distal longer than proximal |
O. magna | moderately muscular, slender / nearly equal diameter with penis | smooth surface of longitudinal folds | papillae arranged in oblique rows | distal shorter than proximal |
O. shanensis | muscular, large / ca. same diameter with penis | corrugated surface of longitudinal folds | reticulated pattern | distal longer than proximal |
Genitalia
(n = 5). Atrium (at) short; penis (p) muscular, cylindrical, and gradually narrower towards epiphallus. Epiphallus (ep) muscular, cylindrical, ca. same as penis length and size, and gradually widening to proximal end. Penial retractor muscle (pr) attached proximally to epiphallus. Vas deferens (vd) slender, and shortly bounded at atrium and penis junction (Fig.
Genital anatomy of A–D Phaedusa shanica, specimen
Vagina (v) slender at junction of atrium, then bulging at connection of free oviduct (fo) and distal part of pedunculus (dpb), and almost as long as free oviduct. Distal part of pedunculus large, long, and basally stouter; diverticulum (db) slender, nearly equal to dpb length; proximal part of pedunculus (ppb) large, long, measuring ~ 3/4 of diverticulum length, and bursa copulatrix (bb) ovoid (Fig.
Radula. Each row contains ~ 47 teeth with half-row formula: central–(lateral)–marginal teeth (1–(11–12)–23). Central tooth symmetrically tricuspid; mesocone large with pointed tip; ectocones triangular and located near the base. Lateral teeth asymmetrically bicuspid with small and pointed ectocone located at base; endocone large with pointed tip. Marginal teeth with asymmetrical tricuspids starting at approximately tooth number 11 or 12; mesocone large with dull tip; endocone and ectocone with small and pointed tips. Marginal teeth gradually reduced in size and becoming multicuspid marginally (Fig.
Phaedusa shanica is collected from probably nearby the type locality and likely restricted in Myanmar. It appears to be quite abundant in the limestone hills based on the high numbers collected in our samplings.
Phaedusa shanica is very similar to P. theobaldi (Blanford, 1872) in having two or three palatal plicae which tend to connect at the second and third plicae. Phaedusa theobaldi (Fig.
Our specimens slightly differ from the type specimen in having three separated palatal plicae, or sometimes second and third plicae well developed and connected (Fig.
In addition, Phaedusa lypra (Mabille, 1887) from Shan State also resembles this species in shell form; however, P. lypra has a blunter spire, less turreted shell, and wider aperture sinus (
Clausilia [Phaedusa (Euphaedusa)] burmanica Gude, 1914: 311, fig. 106. Type locality: “Burma, Tonghu” [Taungoo District, Bago Region, Myanmar].
Phaedusa (Phaedusa) burmanica
–
Phaedusa burmanica
–
Myin Ma Hti Cave, Kalaw City, Shan State, Myanmar (20°35'26.1"N, 96°36'42.6"E):
Shell fusiform, turreted, translucent, and pale chestnut-brown; spire acute. Shell surface glossy with thin and dense striations; suture distinct. Whorls 12–13, little convex, regularly growing and attenuated to apex; last whorl compressed. Aperture vertically subquadrate, basis rounded and narrowing towards parietal sinus; peristome slightly protruded, thickened, and expanded. Superior lamella low, continuous with spiralis, and very low at transition to spiralis. Inferior lamella spirally ascending, close to superior lamella and ending at peristome. Subcolumellaris emerged, and visible in oblique view. Principalis running along lateral-dorsal side and anterior end visible through oblique apertural view. Palatal plicae lateral, distinctly five: first plica strong, longest, and nearly connected to principalis anteriorly; second and fifth plicae almost equal and slightly strong; third and fourth plicae weakest and almost not visible. Palatal plicae visible through translucent shell. Clausilium plate lateral side, broad, rounded and with hook.
Genitalia
(n = 1). Atrium (at) short and slender; penis (p) muscular, cylindrical, broadest at middle part and gradually narrower towards epiphallus. Epiphallus (ep) muscular, cylindrical, ca. same length and size as penis, gradually enlarging to proximal end. Penial retractor muscle (pr) attached proximally to epiphallus. Vas deferens (vd) slender, and shortly bounded at atrium and penis junction (Fig.
Vagina (v) slender at junction of atrium, then bulging at connection of free oviduct (fo) and distal part of pedunculus (dpb), and almost as long as free oviduct. Distal part of pedunculus large, long, basally stouter, and broadest near entrance of diverticulum; diverticulum (db) large, as long as dpb; proximal part of pedunculus (ppb) large, measuring ~ 1/2 diverticulum length, and bursa copulatrix (bb) ovoid (Fig.
Radula. Each row contains ~ 51 teeth with half-row formula: central–(lateral)–marginal teeth (1–(13–14)–25). Central tooth small, symmetrically tricuspid; mesocone large with dull tip; ectocones very small. Lateral teeth asymmetrically bicuspid: endocone large and with dull tip; ectocone very small, pointed tip and located near the base. Marginal teeth tricuspid starting at approximately tooth number 13 or 14; mesocone long and dull tip; endocone very small and located near tip of mesocone; ectocone small with pointed tip. Marginal teeth gradually becoming polycuspid towards radula margin (Fig.
Apart from the type locality, this species is widely known from Bhamo, Kachin State (
Phaedusa bocki menglunanensis from Shan State can be distinguished from this species by its inferior lamella less spirally ascending, palatal plicae longer, obliquely arranged and more spaced between them, shell surface finer and more curved striations, aperture vertically quadrate, and subcolumellaris distinctly visible in frontal view. Phaedusa bocki thompsoni Grego & Szekeres, 2021 also differs from this species in having a more vertical aperture, acute spire, and palatal plicae more on dorsal side (see
Variation was observed among the examined specimens in having the superior lamella and spiralis either separated or connected.
Hemiphaedusa menglunanensis
Phaedusa (Phaedusa) bocki menglunanensis
–
Phaedusa bocki menglunanensis
–
Aik Kham Cave, Taunggyi City, Shan State, Myanmar (20°49'7.0"N, 97°13'42.0"E):
Shell fusiform, translucent, and pale yellowish brown; spire regularly acute. Shell surface with fine and coarse striations; suture wide and distinct. Whorls 12 and 13 nearly flattened, regularly increasing, and attenuated to apex. Aperture vertically subquadrate, basis rounded and narrowing towards parietal sinus; peristome protruded, expanded and little reflexed. Superior lamella low, continuous with spiralis, and low at transition to spiralis. Inferior lamella spirally ascending, slightly horizontal before reaching peristome and close to superior lamella. Subcolumellaris emerged, ending at peristome margin, and clearly visible in frontal view. Principalis running along lateral-dorsal side and anterior end visible through oblique apertural view. Palatal plicae lateral, four or five: first plica distinct, longest, and nearly connected to principalis anteriorly; second plica ~ 1/2 of first plica length and remaining plicae oblique, equally spaced, and shorter. Palatal plicae visible through translucent shell. Clausilium plate lateral side, broad, rounded, and with hook.
Phaedusa bocki menglunanensis was originally described from Yunnan Province, China, which is near the borders with Vietnam and Laos. It was recently found in Shan State, along the Mekong River near the border with Laos (
No preserved specimens were found for examination of the genitalia. This subspecies and samples of P. bocki thompsoni collected from the same geographical range have a similar shell morphology, but P. bocki thompsoni has invisible subcolumellaris in frontal view, blunter and turreted spire, and whorls after antepenultimate whorl rapidly attenuated (see
Clausilia (Oospira)
Blanford, 1872: 205.
Phaedusa (Oospira)
–
Oospira
–
Clausilia philippiana Pfeiffer, 1847, by original designation.
Shell short to long fusiform, shell surface smooth to with striated ridges, spire blunt to attenuated, whorls few to numerous (6–13). Palatal plicae short to long, mostly developed and 3–10 in number. Superior lamella developed, usually connected to spiralis, distinct or indistinct at transition to spiralis. Inferior lamella steeply ascending and somewhat ending distant from superior lamella in aperture view. Subcolumellaris usually invisible in frontal view; clausilium plate lateral to ventral side and usually narrow.
Living animals possess reticulated skin; dark gray head; short tentacles; body and tail pale to dark brownish; foot moderately elongated, posterior nearly rounded to bluntly pointed.
Oospira is the most species-rich genus of the Phaedusinae, and more than a hundred species have been reported from a broad range in Southeast Asia (MolluscaBase 2022).
The genera Loosjesia from Thailand, Messageriella Páll-Gergely & Szekeres, 2017 and Castanophaedusa Páll-Gergely & Szekeres, 2017 from Vietnam, Musaphaedusa Nordsieck, 2018 from Laos, and Oospira have a similar shell morphology, especially in the form of the palatal plicae. However, Loosjesia can readily be differentiated by its predominantly curved basal inferior lamella with a long transverse palatal plica and clearly visible subcolumellaris (
Regarding the reproductive anatomy of this group, Oospira penangensis (Stoliczka, 1873) and O. philippiana were the first species examined for their genitalia (
Based on shell morphology, we have divided Oospira from Myanmar into two species groups comprised of those with (i) short and ovate fusiform shells and (ii) long and slender fusiform shells. The short and ovate fusiform group includes the species believed to be Oospira s.s. (type species Clausilia philippiana Pfeiffer, 1847), while the long and slender fusiform group assumed to be the species previously known as ‘Pseudonenia Boettger, 1877’ (type species Clausilia javana Pfeiffer, 1841).
In Myanmar, this group is comprised of five species, four of which were collected and examined, while O. vespa (Gould, 1856) was not.
Clausilia philippiana
Pfeiffer, 1847: 69. Type locality: “Mergui in imperio Birmanorum” [near Myeik, Tanintharyi Region, Myanmar]. Küster 1850: 100, pl. 11, figs 7–9.
Clausilia (Phaedusa) philippiana
–Adams and Adams 1855: 184.
Clausilia (Oospira) philippiana
–
Clausilia
[Phaedusa (Oospira)] philippiana–
Oospira (Oospira) philippiana
–
Oospira philippiana
–
Possible syntype
Shell and clausilial apparatus of A–C Oospira philippiana A possible syntype
Shell ovate-fusiform, opaque, and chestnut-brown color; spire blunt. Shell surface nearly smooth or with very thin striations; suture distinct. Whorls 5–6½, convex, regularly growing and bluntly attenuated to apex. Aperture obliquely pear-shaped, basis broader and narrowing towards parietal sinus; peristome detached, thickened, expanded and little reflexed. Superior lamella developed, continuous with spiralis, and low at transition to spiralis. Inferior lamella steeply ascending, distant from superior lamella and ending at peristome. Subcolumellaris emerged, and only visible in oblique view. Principalis running along lateral-dorsal side and anterior end visible through oblique apertural view. Palatal plicae lateral, 7–9: first plica strong and longest; following plicae shorter, parallel, nearly equal in length, gradually reduced towards anterior. Clausilium plate lateral side, slightly broad and rounded at tip.
Genitalia (n = 5). Atrium (at) short and slender; penis (p) muscular and cylindrical. Epiphallus (ep) muscular, cylindrical, ca. same length and half of the diameter of penis and broadest at middle part. Penial retractor muscle (pr) attaches proximally to epiphallus. Vas deferens (vd) slender, and shortly bounded at atrium and penis junction (Fig.
Genital anatomy of A–C Oospira philippiana, specimen
Vagina (v) thick and very short, ~ 1/3 of free oviduct (fo) length. Distal part of pedunculus (dpb) large and long; diverticulum (db) long, ~ 2× length and slightly larger diameter than dpb; proximal part of pedunculus (ppb) slender, ca. equal in length to diverticulum, and bursa copulatrix (bb) with distinct ovate shape (Fig.
Radula. Each row contains ≥ 39 teeth with half-row formula: central–(lateral)–marginal teeth (1–(11–12)–19+). Central tooth unicuspid with rounded to blunt tip. Lateral teeth bicuspid: endocone large and rounded tip; ectocone very small, pointed tip and located near the base. Marginal teeth asymmetrically tricuspid starting at approximately tooth number 11 or 12: mesocone large and curved to blunt tip; endocone small and located near tip of mesocone; ectocone triangular, pointed tip and located near the base. Outermost teeth have been lost during the preparation process (Fig.
In Myanmar, this species is reported from Kayin, Mon and Tanintharyi (
Oospira stoliczkana can be distinguished from O. philippiana by its elongate ovoid shell, pale color, and higher numbers of plicae. In terms of the genital organs, the male internal sculpture of O. philippiana has thicker and denser corrugated folds near the atrium than in O. stoliczkana (Fig.
Among the examined specimens, those from the Pha Boang Cave population (24 shells) have larger and darker shells with more widely spaced and up to nine developed palatal plicae. In contrast, specimens from the Kayon Cave (21 shells) and Saddan Cave (15 shells) populations are uniform in terms of a smaller shell and seven closer and weaker plicae (Table
No specimens were found at the type locality ‘Mergui’ [Myeik]; but
Clausilia bulbus
Benson, 1863: 321. Type locality: “ad ripas fluvii Attaran, non procul ab urbe Moulmein” [banks of Attaran River, Mawlamyine, Mon State, Myanmar].
Clausilia (Oospira) bulbus
–
Clausilia
[Phaedusa (Oospira)] bulbus–
Oospira (Oospira) bulbus
–
Oospira bulbus
–
Sanbel Cave, Mawlamyine Township, Mon State, Myanmar (16°22'26.0"N, 97°46'22.6"E):
Shell oblong-ovate, translucent, and brownish; spire rounded and almost flatted to apex. Shell surface with fine and distinct striations; suture wide and distinct. Whorls 5–5½; penultimate whorl rapidly growing and largest; last whorl compressed and narrower. Aperture obliquely pear-shaped, basis rounded and narrowing towards parietal sinus; peristome detached, thickened, slightly expanded, and not reflexed. Superior lamella sharp, oblique, continuous with spiralis, and low at transition to spiralis. Inferior lamella steeply ascending, distant from superior lamella and ending at peristome. Subcolumellaris emerged and invisible in oblique view. Principalis running along lateral-dorsal side and anterior end visible through oblique apertural view. Palatal plicae lateral, five: first plica longest; following four plicae parallel, equal in length and spacing, and slightly reduced towards anterior. Clausilium plate lateral side and narrow.
Genitalia
(n = 2). Atrium (at) short and slender; penis (p) muscular and cylindrical. Epiphallus (ep) muscular, cylindrical, ca. same length and half diameter of penis, and broadest at middle part. Penial retractor muscle (pr) attaches proximally to epiphallus. Vas deferens (vd) slender, and shortly bounded at atrium and penis junction (Fig.
Vagina (v) thick and short, ~ 1/2 of free oviduct (fo) length. Distal part of pedunculus (dpb) large and long; diverticulum (db) long, ~ 2× in length and slightly smaller in diameter than dpb; proximal part of pedunculus (ppb) slender, ca. equal in length to diverticulum and bursa copulatrix (bb) with distinct ovate shape (Fig.
Oospira bulbus has only been reported from Myanmar and is possibly endemic in the limestone hills along the lower course of Attaran River. The specimens examined herein were collected near the type locality.
Oospira ovata can be separated from this species by its a smoother striated shell, attenuated spire and usually seven plicae. In terms of the genital organs, the male internal sculpture of O. ovata has longer V-shaped folds in the region near the atrium and rounded papillae in epiphallus than this species. Although O. bulbus has a similar shell form to Atractophaedus pyknosoma (Gittenberger & Vermeulen, 2001) from Vietnam, A. pyknosoma has a narrower spire, visible subcolumellaris in frontal view, peristome reflected with nearly double lip and first palatal plicae shorter than the following plicae (see
Clausilia (Oospira) ovata
Blanford, 1872: 206, pl. 9, fig. 17. Type locality: “Ad Nattoung, juxta ripam Attaran fluminis, haud procul a Moulmain in Barma” [Shwe Nat Taung, Mawlamyine, Mon State, Myanmar].
Clausilia ovata
–Hanley and Theobald 1874: 48, pl. 118, fig. 4.
Clausilia
[Phaedusa (Oospira)] ovata–
Oospira (Oospira) ovata
–
Oospira ovata
–
Pathein Mountain, Mawlamyine Township, Mon State, Myanmar (16°14'7.5"N, 97°56'48.1"E):
Shell and clausilial apparatus of A–C Oospira ovata, specimen
Shell ovate or pupiform, opaque and chestnut-brown; spire blunt. Shell surface nearly smooth or with very thin growth lines; suture distinct. Whorls 5–5½ convex, rapidly growing; penultimate and antepenultimate whorls equally broad and rounded to apex. Aperture obliquely pear-shaped, basis rounded and narrowing towards parietal sinus; peristome detached, thickened, expanded and little reflexed. Superior lamella well developed, continuous with spiralis and low at transition to spiralis. Inferior lamella steeply ascending, distant from superior lamella and ending at peristome. Subcolumellaris emerged and only visible in oblique view. Principalis running along lateral-dorsal side and anterior end visible through oblique apertural view. Palatal plicae lateral, six or seven: first plica strong and longest; following plicae short, parallel, equal in length and gradually reduced towards anterior. Clausilium plate lateral side and narrow.
Genitalia
(n = 1). Atrium (at) short and slender; penis (p) muscular and cylindrical. Epiphallus (ep) muscular, cylindrical, ~ 1.5× diameter of penis, and broadest close to penis. Penial retractor muscle (pr) attaches proximally to epiphallus. Vas deferens (vd) slender and shortly bounded at atrium and penis junction (Fig.
Genital anatomy of A–D Oospira ovata, specimen
Vagina (v) thick, short, and almost half of free oviduct (fo) length. Distal part of pedunculus (dpb) large and long; diverticulum (db) large, slightly longer, and larger in diameter than dpb; proximal part of pedunculus (ppb) slender, ~ 2/3 diverticulum length and bursa copulatrix (bb) with distinct ovate shape (Fig.
Radula. Each row contains ~ 61 teeth with half-row formula: central–(lateral)–marginal teeth (1–(12–13)–26). Central tooth unicuspid with dull tip. Lateral teeth bicuspid; endocone large with curved to dull tip; ectocone very tiny to small and pointed tip. Marginal teeth asymmetrically tricuspid starting at approximately tooth number 12 or 13: mesocone large and dull tip; ectocone and endocone small with pointed tips. Outer marginal teeth increasingly asymmetrical and shorter than inner marginal teeth (Fig.
At present, O. ovata is only known from Myanmar. Many shells were collected in this study; it is likely endemic to the valley of Attaran River.
Oospira ovata and O. philippiana are generally similar in shell morphology, but O. ovata has a more expanded spire. The male internal sculpture of O. ovata has longer V-shaped folds in the region near the atrium and rounded papillae pattern in epiphallus, whereas O. philippiana has shorter V-shaped folds and more elevated and pointed papillae in epiphallus.
Clausilia vespa
–
Clausilia vespa
–
Clausilia (Oospira) stoliczkana
Sykes, 1893: 166. Type locality: “Tavoy, Burmah” [Dawei, Tanintharyi Region, Myanmar].
Oospira (Oospira) stoliczkana
–
Oospira stoliczkana
–
Phra Cave, Tanintharyi Region, Myanmar (11°13'46.2"N, 99°10'34.3"E):
Shell elongate ovoidal, glossy, translucent, and horny brown; spire blunt. Shell surface with very thin striations to smooth surface; suture wide and distinct. Whorls 6–6½, convex, regularly growing and bluntly attenuated to apex. Aperture obliquely pear-shaped, basis rounded and narrowing towards parietal sinus; peristome detached, thin and little expanded. Superior lamella developed, sharp, continuous with spiralis and low at transition to spiralis. Inferior lamella steeply ascending, distant from superior lamella and ending at peristome. Subcolumellaris emerged and only visible in oblique view. Principalis running along lateral-dorsal side and anterior end visible through oblique apertural view. Palatal plicae lateral, 8–10: first plica strong and longest; following four plicae parallel and equal in length, and remaining plicae shorter, closer, gradually reduced towards anterior. Clausilium plate lateral side and slightly broad at tip.
Genitalia
(n = 1). Atrium (at) short and slender; penis (p) muscular and cylindrical. Epiphallus (ep) muscular, cylindrical, slightly longer by 1.5× diameter of penis, and broadest at proximal part. Penial retractor muscle (pr) attaches proximally to epiphallus. Vas deferens (vd) slender, and shortly bounded at atrium and penis junction (Fig.
Vagina (v) large, short, and almost half the length of free oviduct (fo). Distal part of pedunculus (dpb) large and long; diverticulum (db) long, ca. same length as dpb; proximal part of pedunculus (ppb) slender, almost equal in length to diverticulum, and bursa copulatrix (bb) small, ovateshape (Fig.
This species is known from Mon State, along with its type locality in Tanintharyi Region; no reports have been made outside Myanmar to date (
Oospira stoliczkana can be distinguished from all other species with an ovate-fusiform shell (O. philippiana, O. ovata, O. bulbus, and O. vespa) by its elongate ovoidal shell, thinner peristome, and 8 to 10 palatal plicae. Although only one ethanol-preserved specimen could be examined, the internal sculpture of the penis and epiphallus of O. stoliczkana differs from O. philippiana, O. bulbus, and O. ovata by its very short V-shaped folds in the region near the atrium and more elevated and pointed papillae in epiphallus.
Some of the examined specimens had a thin and translucent shell, with more distinct palatal plicae.
In Myanmar, this group comprises 15 species including two new ones. Six of these species are examined herein; the remaining nine are O. arakana (Stoliczka, 1872), O. decollata (Likharev, 1962), O. fusiformis (Blanford, 1865), O. gracilior (Hanley & Theobald, 1870), O. insignis (Gould, 1843), O. limborgi Grego & Szekeres, 2021, O. malaisei Nordsieck, 1973, O. mongmitensis Grego & Szekeres, 2021 and O. sardicola Grego & Szekeres, 2021.
Clausilia gouldiana
Pfeiffer, 1857: 259. Type locality: “Mergui imperii Birmani” [Myeik Islands, Tanintharyi Region, Myanmar].
Clausilia (Phaedusa) gouldiana
–
Clausilia
[Phaedusa (Pseudonenia)] gouldiana–
Oospira (Oospira) gouldiana
–
Oospira gouldiana
–
Bardai Mountain, Hpa-an Township, Hpa-an District, Kayin State, Myanmar (16°59'10.4"N, 97°42'19.8"E):
Shell and clausilial apparatus of Oospira gouldiana A–C specimen
Shell fusiform, translucent, brownish to reddish pink, and 3–4 white apical whorls; spire regularly attenuated. Shell surface finely striated to nearly smooth surface; suture impressed and distinct. Whorls 10–12 convex, regularly growing or sometimes rapidly growing after antepenultimate whorl and attenuated to apex. Aperture pear-shaped, basis broader and narrowing towards parietal sinus; peristome slightly protruded, thickened, expanded, and indistinctly doubled. Superior lamella developed, continuous with spiralis and slightly low at transition to spiralis. Inferior lamella steeply ascending, distant from superior lamella and ending at peristome. Subcolumellaris emerged and invisible in oblique view. Principalis running along lateral-dorsal side and anterior end visible through oblique apertural view. Palatal plicae lateral, five or six: first plica strong and longest; following plicae short, more or less parallel; fourth or fifth plica longer than middle plicae. Clausilium plate lateral side and narrow.
Genitalia
(n = 5). Atrium (at) short and slender; penis (p) long, slender, and shortly narrower at transition to epiphallus. Epiphallus (ep) slender, ca. same length as penis, slightly smaller diameter, and broadest at middle. Penial retractor muscle (pr) attaches proximally to epiphallus. Vas deferens (vd) thin and shortly bounded at penis (Fig.
Vagina (v) thick, cylindrical, and almost half of free oviduct (fo) length. Distal part of pedunculus (dpb) large and middle part broadest; diverticulum (db) slender, very long, ca. same length as distal part and proximal part of pedunculus; proximal part of pedunculus (ppb) slender, nearly same length as (dpb), and bursa copulatrix (bb) ovoid (Fig.
Radula. Each row contains ≥ 39 teeth with half-row formula: central–(lateral)–marginal teeth (1–(11–12)–19). Central tooth tricuspid with large and triangular mesocone, and ectocones very small and pointed tips. Lateral teeth bicuspid: endocone large and triangular; ectocone very small and pointed tip. Marginal teeth asymmetrically tricuspid starting at approximately tooth number 11 or 12: endocone small located near the tip; mesocone large and dull to blunt tip; ectocone with triangular shape, pointed tip and located near the base (Fig.
Oospira gouldiana is the most abundant species of the genus in Myanmar, occurring mainly in the south-eastern part of the country. This species was abundant at seven limestone outcrops in Kayin State (Fig.
Oospira gouldiana specimens from Taung Lay Cave are quite similar to O. malaisei from Kachin State in terms of shell form. But O. malaisei (Fig.
Oospira gouldiana also shares a similar shell morphology with O. insignis exhibiting a regularly attenuated spire with whitish apical whorls, palatal plicae five, and a broad pear-shaped aperture. Nevertheless, O. gouldiana has a more attenuated spire, more parallel palatal plicae, aperture more vertical, and less glossy than O. insignis. In addition, this species can easily be separated from O. shanensis by its pale color, shorter and oblique palatal plicae, inferior lamella more spirally and closely ascending from spiralis and superior lamella. Oospira penangensis differs from this species by its less ventricose, narrower, and more vertical subquadrate aperture, inferior lamella ending straight at peristome and weaker superior lamella from apertural view.
Oospira gouldiana is highly variable in terms of shell color and shape. The typical form was found in the Bardai and Kaw Ka Thaung populations, showing a yellowish to pinkish color with a regular fusiform shape (Fig.
Except for the Sadhdan, Taung Lay, and Rathye Pyan populations, for which genitalia could not be examined, the remaining populations are similar in external genital morphology, with only slightly differing thickness of the longitudinal folds of the internal sculpture of the penis being observed. However, these four populations inhabit a very small geographical area, hence we attribute this minor difference to morphological variation.
Clausilia (Pseudonenia) andersoniana Möllendorff, 1882: 12, pl. 1, fig. 13. Type locality: “In insula Mergui provincise Tenasserim” [Myeik Islands, Tanintharyi Region, Myanmar].
Clausilia
[Phaedusa (Pseudonenia)] andersoniana–
The type specimens could not be located in the Senckenberg Museum, Frankfurt (K.-O. Nagel and S. Hof, pers. comm., April 2022). Phra Cave, Tanintharyi Region, Myanmar (11°13'46.2"N, 99°10'34.3"E):
Shell and clausilial apparatus of A, B Oospira andersoniana, specimen
Shell fusiform, translucent, and pale yellowish brown color; spire regularly attenuated. Shell surface glossy and almost smooth surface; suture impressed and distinct. Whorls 9–10, little convex, regularly growing and attenuated to apex. Aperture pear-shaped, and basis broader and narrowing towards parietal sinus; peristome protruded, little thickened and expanded. Superior lamella developed, continuous with spiralis, and indistinct at transition to spiralis. Inferior lamella steeply ascending, distant from superior lamella and ending at peristome. Subcolumellaris emerged and invisible in oblique view. Principalis running along lateral-dorsal side and anterior end visible through oblique apertural view. Palatal plicae lateral, 3–5 (usually 3): all plicae very strong, parallel, equal length, spacing, and one or two small plicae sometimes present in middle and at lowest. Clausilium plate lateral side and narrow.
Genitalia
(n = 5). Atrium (at) short and slender; penis (p) almost cylindrical and shortly narrower at transition to epiphallus. Epiphallus (ep) cylindrical, ca. same length and diameter as penis. Penial retractor muscle (pr) attaches proximally to epiphallus. Vas deferens (vd) thin and shortly bounded at penis (Fig.
Genital anatomy of A–D Oospira gouldiana, specimen
Vagina (v) thick, cylindrical, and almost equal to free oviduct (fo) length. Distal part of pedunculus (dpb) large and long; diverticulum (db) thin and ca. same length as dpb; proximal part of pedunculus (ppb) slender, nearly equal in length to diverticulum, and bursa copulatrix (bb) small, ovoid (Fig.
Radula. Each row contains ~ 45 teeth with half-row formula: central–(lateral)–marginal teeth (1–(10–11)–22). Central tooth tricuspid: mesocone triangular with dull cusp; ectocones small and pointed tip. Lateral teeth bicuspid: endocone large and with dull cusp; ectocone small with tip pointed laterally. Marginal teeth asymmetrically tricuspid starting at approximately tooth number 10 or 11: endocone very tiny; mesocone large, elongate, blunt tip; ectocone small, triangular, pointed tip. Outermost becoming smaller and more asymmetrical than inner teeth (Fig.
Currently O. andersoniana is only known from Tanintharyi Region, Myanmar.
This species was described based on two shells collected by the Scottish zoologist, John Anderson (1833–1900), approximately from southern Myanmar, and an illustration was included in the original publication (
In this survey, Oospira andersoniana and O. stoliczkana were collected from the same locality in the Tanintharyi Region. These two species are similar in possessing a nearly smooth shell glossy surface, thin peristome, pale yellowish color, and less developed inferior lamella. However, O. stoliczkana exhibits a shorter, blunt spire, broader clausilium and several palatal plicae (from 8 to 10).
Compared with the other congeners, Oospira andersoniana can be distinguished from O. insignis, O. gouldiana, and O. magna by its less ventricose shell, smoother surface and pale color, peristome and inferior lamella weaker, and palatal plicae longer and more uniformly arranged. In contrast, O. insignis possesses oblique palatal plicae, more ventricose and darker colored shell, while O. gouldiana has a ventricose shell, spire more attenuated and with whitish apical whorls, inferior lamella more bent, aperture thicker and broader, and palatal plicae closer and more oblique. In addition, O. magna can be distinguished from O. andersoniana by having a finely and densely striated shell surface, inferior lamella well developed, clausilium in ventral position, and palatal plicae longer and more ventral (nearly horizontal). In terms of the genitalia, O. andersoniana has a short male organ, internal penis with large longitudinal folds and epiphallus with a distinct reticulated papillae pattern. In contrast, O. gouldiana and O. magna possess slender and longer male organs, internal penis with thinner and denser longitudinal folds, and epiphallus with irregularly arranged reticulated papillae patterns. Furthermore, O. limborgi Grego & Szekeres, 2021, also described from the Tanintharyi Region, shares some characteristics with this species in having the same number of palatal plicae, nearly triangular aperture, glossy and pale yellowish color (see
Shell variation was observed with respect to a small and short plica between the first and second palatal plicae.
Clausilia [Phaedusa (Pseudonenia)] gouldianavar. magna Gude, 1914: 316, fig. 109. Type locality: “Moulmain and Phaboo” [Mawlamyine, Mon State and Pabu, Hpa-an, Kayin State, Myanmar].
Bayin Nyi Cave, Hpa-an Township, Kayin State, Myanmar (16°58'10.1"N, 97°29'30.6"E):
Shell fusiform, translucent, yellowish brown and 3–4 white apical whorls; spire regularly attenuated. Shell surface nearly smooth to with thin growth lines; suture deep and distinct. Whorls 10–11, convex, regularly growing and attenuated to apex. Aperture oval-pear-shaped, less oblique, basis broader and narrowing towards parietal sinus; peristome protruded, thickened, and slightly expanded. Superior lamella developed, continuous with spiralis, and indistinct at transition to spiralis. Inferior lamella well developed, steeply ascending, distant from superior lamella and ending at peristome. Subcolumellaris emerged and invisible in oblique view. Principalis running along ventral-lateral side and anterior end visible through oblique apertural view. Palatal plicae ventral-lateral, 4–6 (usually 4): first plica strong and longest; second and third plicae short, parallel, oblique, and equal in length; fourth plica longer and stronger than middle plicae. Clausilium plate ventral side and narrow.
Genitalia
(n = 1). Atrium (at) short and relatively large; penis (p) almost cylindrical and shortly narrower at transition to epiphallus. Epiphallus (ep) slender, ca. same length as penis and smaller diameter. Penial retractor muscle (pr) attaches proximally to epiphallus. Vas deferens (vd) almost same diameter as epiphallus and shortly bounded at penis (Fig.
Genital anatomy of A–D Oospira magna, specimen
Vagina (v) thick, cylindrical, and almost equal in length to free oviduct (fo). Distal part of pedunculus (dpb) cylindrical and long; diverticulum (db) very long, slightly enlarged at basis, then gradually slenderer, ~ 3× times length of dpb; proximal part of pedunculus (ppb) slender, slightly short, ~ 3/4 diverticulum length; bursa copulatrix (bb) large, ovoid (Fig.
Oospira magna is only recorded from the southern part of the country to the limestone area of the Salween River Basin in Mon and Kayin States, Myanmar.
Originally, Oospira magna was proposed as a subspecies of O. gouldiana based on its distinct less ventricose shell and seven palatal plicae (
Oospira shanensis
Grego & Szekeres in
Limestone outcrop at Nanthe Cave, Kalaw City, Shan State, Myanmar 20°35'16.6"N, 96°37'57.2"E:
Shell fusiform, opaque, and dark yellowish color; 5–6 apical whorls rapidly attenuated. Shell surface glossy and almost smooth; suture impressed and distinct. Whorls 12½–13, last four whorls regularly growing and then rapidly attenuated to apex. Aperture obliquely or elliptical, basis oblique and broadest and narrowing towards parietal sinus; peristome attached, thickened, and expanded. Superior lamella developed, continuous with spiralis and indistinct at transition to spiralis. Inferior lamella steeply ascending, anterior end weakly visible in apertural view, very distant from superior lamella and ending at peristome. Subcolumellaris emerged and visible in oblique view. Principalis running along ventral-lateral side and anterior end visible through oblique apertural view. Palatal plicae ventral-lateral, five: equally spaced, fourth plica curved most, two middle plicae equally shorter than first and fourth; fifth plica can only be seen when shell is opened. Clausilium plate lateral side, broad, rounded and with hook.
Genitalia
(n = 2). Atrium (at) small and short; penis (p) almost cylindrical and gradually narrower at transition to epiphallus. Epiphallus (ep) cylindrical and ca. same length and diameter as penis. Penial retractor muscle (pr) attaches proximally to epiphallus. Vas deferens (vd) very thin and shortly bounded at penis (Fig.
Vagina (v) very thin and ~ 1/3 of free oviduct (fo) length. Distal part of pedunculus (dpb) long and enlarged, cylindrical; diverticulum (db) long, enlarged at basal and gradually reduced and becoming slender at terminal, and nearly same length as dpb; proximal part of pedunculus (ppb) short, ~ 3/4 diverticulum length, and bursa copulatrix (bb) small, ovoid (Fig.
Radula. Central and lateral teeth contain ≥ 23 teeth with half-row formula: central–(lateral)–marginal teeth (1–(10–11)+). Central tooth tricuspid: mesocone large and triangular; ectocone small and located near the base. Lateral teeth bicuspid: endocone large and bluntly pointed tip; ectocone small and pointed tip. Marginal teeth asymmetrically tricuspid starting at approximately tooth number 10 or 11 (Fig.
Radula morphology A Oospira philippiana, specimen
This species is presently only known from Shan State, Myanmar.
Among all the Myanmar’s Oospira species studied herein, this is the only species with a clausilium hook (Fig.
Oospira sardicola can be distinguished from O. shanensis by having paler glossy yellowish color, wider and less oblique aperture, and less ventricose shell (
Oospira mongmitensis, O. sardicola, and O. shanensis were recorded from Shan State. All of them are similar in possessing distinct palatal plicae which can be seen through the shell, but different in their pale to dark color, more or less bulging shell and aperture oblique to nearly vertical (
Our specimens show variation in the development of palatal plicae, especially as the fourth or fifth plicae are horizontal to oblique.
Holotype
Shell and clausilial apparatus of A–C Oospira luneainopsis sp. nov. A shell of holotype
Limestone outcrop at Zwegabin Mountain, Hpa-an Township, Hpa-an District, Kayin State, Myanmar (16°48'44.5"N, 97°40'25.5"E).
The specific name luneainopsis is a compound of ‘lun-eain’, which in the Myanmar language refers to a bobbin used for traditional Myanmar weaving, and the Greek suffix -opsis meaning ‘having the appearance of or like’. It refers to the bobbin shape of the shell of this species.
Shell of A Oospira decollata, paratype
Shell ovate-fusiform, decollated with smooth surface and dense striations near suture. Last whorl neck subquadrate; aperture nearly roundish; peristome detached. Inferior lamella straight ascending and reaching at peristome; palatal plicae four, distinct, equally, and parallelly arranged, and superior lamella developed.
Shell ovate-fusiform, decollated, opaque, pinkish brown; spire blunt. Shell surface smooth to with fine growth lines on last whorl, denser near suture and last whorl neck subquadrate; suture impressed and distinct. Whorls 7–8, convex, regularly growing, and bluntly attenuated to apex. Aperture nearly round; peristome detached, thickened, expanded and little reflexed. Superior lamella developed, continuous with spiralis, and slightly low at transition to spiralis. Inferior lamella steeply ascending, distant from superior lamella and ending at peristome. Subcolumellaris emerged and invisible in oblique view. Principalis running along lateral-dorsal side and anterior end visible through oblique apertural view. Palatal plicae lateral, four: first and fourth plicae strong and longest; remaining plicae parallel and equal length; sometimes tiny lowest plica present. Clausilium plate lateral side, narrow and slightly pointed at tip.
Oospira luneainopsis sp. nov. is only known from the type locality.
No ethanol preserved specimens were available for anatomical study. This species can be distinguished from O. gouldiana, O. magna, and O. zediopsis sp. nov. by its small size, decollated, fewer whorls, roundish aperture, more spiral inferior lamella, and equal palatal plicae. This new species is clearly distinct from O. decollata by its spiral inferior lamella visible from aperture, smoother shell, pink color, and more bulging whorls.
Compared to the Vietnamese dextral species, O. duci Maassen & Gittenberger, 2007 exhibits thinner and oblique aperture, sinus higher, obviously emerged subcolumellaris, very fine striations and more ventrally unequal palatal plicae than this species.
Holotype
Weibyan Cave, Hpa-an Township, Hpa-an District, Kayin State, Myanmar (17°13'38.2"N, 97°37'24.0"E).
The specific name zediopsis is a compound word; ‘zedi’ is one of several terms in the Myanmar language that refer to a stupa or pagoda, and the Greek suffix -opsis means ‘having the appearance of or like’. It refers to the Myanmar pagoda-like shell shape of this species.
Shell fusiform, with four to five white apical whorls, and nearly smooth shell surface. Inferior lamella straight ascending or almost flattened, palatal plicae lateral, equally oblique, superior lamella distinct at transition to spiralis, and clausilium plate lateral side and less bent inwards.
Shell fusiform, opaque, and chestnut-brown color; 4–5 apical whorls white and rapidly attenuated. Shell surface smooth to with very thin growth lines; suture impressed and distinct. Whorls 10–11, convex, regularly growing, and attenuated to apex. Aperture obliquely pear-shaped, and basis rounded; peristome slightly protruded, large, relatively thickened and slightly expanded. Superior lamella developed, connected to spiralis and slightly low at transition to spiralis. Inferior lamella steeply ascending, distant from superior lamella and ending at peristome. Subcolumellaris emerged and invisible in oblique view. Principalis running along lateral-dorsal side and anterior end visible through oblique apertural view. Palatal plicae lateral, four or five: first and fourth plicae strongest and longest; remaining plicae parallel and equal length; fifth plica smallest. Clausilium plate lateral side and narrow.
This species is only known from the type locality with plentiful shells collected.
No ethanol preserved specimens were available for anatomical study. Oospira gouldiana can be distinguished from O. zediopsis sp. nov. by its less ventricose shell, denser and stronger striations, more spiral inferior lamella, palatal plicae and clausilium more ventrally positioned, and principalis not visible from the aperture view. Likewise, O. shanensis can be differentiated from this new species by wider spacing between spiralis and inferior lamella, anterior end of inferior lamella reduced at peristome, longer palatal plicae, attached peristome, and clausilium wider and with a hook. Furthermore, O. zediopsis sp. nov. can be differentiated from O. insignis by its more attenuated spire, narrower and more oblique aperture, shorter and more equal palatal plicae.
Among the 33 clausiliid taxa recorded from Myanmar, 13 species are redescribed here based on the shell, genitalia, and radular morphologies, including two new species. The remaining 20 species are known from literature, and images of the type specimens, authenticated specimens or original illustrations are provided for further comparison (Figs
Synoptic view of the clausiliid species recorded from Myanmar A Indonenia admirabilis, holotype
Synoptic view of the clausiliid species recorded from Myanmar A Phaedusa lypra, syntype
In Myanmar, Oospira is one the most diverse stylommatophoran genera. It comprises 20 species of which ten are redescribed herein, including the type species, O. philippiana. Based on the shell, clausilial apparatus and genital morphology, the genus is generally divided into two groups: (1) short and ovate fusiform shell group (including type species), and (2) long and slender fusiform shell group. The first group tends to have palatal plicae reduced towards the anterior, inferior lamella straight ascending and superior lamella distinct from spiralis at its transition point, a well-developed penis, diverticulum, and proximal of pedunculus almost similar in length, internal wall of epiphallus with equally and obliquely arranged papillae, and internal wall of penis consists of two shapes: oblique V-shaped near atrium and transitioning to longitudinal folds near epiphallus. The second group possess palatal plicae that are not reduced towards the anterior, inferior lamella more spirally ascending (S-shape) and superior lamella indistinct from spiralis at it transition point, slender to narrowly cylindrical penis, generally diverticulum longer than proximal of pedunculus in length, internal wall of epiphallus with irregularly arranged papillae, and internal wall of penis consists of longitudinal folds throughout the entire chamber. Additionally, the central tooth of group (1) has a more rounded cusp than group (2), which has a triangular shape and pointed cusp. These differences in shell and clausilial apparatus between the two groups rather agree with the diagnostic characters of the Pseudonenia Boettger, 1877 (see
Although the clausiliids seem evenly distributed throughout Myanmar, Phaedusa is distributed in the northeast to southwest, while Oospira occurs widely along the northernmost to the southernmost parts of the country (Fig.
Despite the numbers of the Myanmar clausiliids are increasing, the taxonomic placements of some species are still questionable, for example, Oospira gouldiana and O. insignis which are morphologically highly variable and have overlapping distributions. Previous studies have attempted to reveal their differentiation, but this remains ambiguous (
Below is an alphabetical list of 20 clausiliid species and subspecies belonging to the genera Cylindrophaedusa, Indonenia Ehrmann, 1927, Oospira, and Phaedusa that have been reported to occur in Myanmar, but that were not found during this study. The usages of each taxon name are provided in
1 Cylindrophaedusa bacillum (Hanley & Theobald, 1870)
Fig.
Clausilia bacillum Hanley & Theobald, 1870: 12, pl. 24, fig. 1. Type locality: “Nanclai, Khasi Hills”.
Clausilia (? Medora) bacillum–
Clausilia (Phaedusa) bacillum–
Hemiphaedusa bacillum–
Cylindrophaedusa (Montiphaedusa) bacillum–
Distribution. In Myanmar, this species is known from Schegoo (presumably Shwegu), Bhamo City in Kachin State; no further materials have been reported from Myanmar after its mention in
2 Oospira arakana (Stoliczka, 1872)
Fig.
Clausilia arakana Stoliczka, 1872: 210, pl. 9, fig. 20. Type locality: “Mai-i in provincia Sandoway” [Mwa-ywa, Thandwe Township, Rakhine State]. Hanley and Theobald 1874: 48, pl. 118. figs 8, 9.
Clausilia (Phaedusa) arakana–
Oospira arakana–
Distribution. This species is probably endemic to Rakhine State, Myanmar.
3 Oospira decollata (Likharev, 1962)
Figs
Pseudonenia decollata Likharev, 1962: 11–13, figs 1, 2. Type locality: “Nat Ma Taung, Chin State, Myanmar”.
Oospira (Oospira) decollata–
Oospira decollata decollata–
Distribution. This species was recorded from Nat Ma Taung, also called Victoria Mountain, Chin State, and as such it is the westernmost clausiliid species recorded in Myanmar. Another subspecies, O. decollata muspratti Grego & Szekeres, 2021 was recently reported from Naga Hills, India (
4 Oospira fusiformis (Blanford, 1865)
Fig.
Clausilia fusiformis Blanford, 1865: 80. Type locality: “Arakan Hill, west of Henzada” [Rakhine State or west of Hinthada Township, Ayeyarwady Region]. Hanley and Theobald 1870: 12, pl. 24, fig. 6.
Clausilia (Phaedusa) fusiformis–
Oospira fusiformis–
Distribution. In Myanmar, this species is known from Rakhine State and Ayeyarwady Region, and also reported from the Bago Region (
Remarks.
The specimen identified as Oospira insignis
5 Oospira gracilior (Hanley & Theobald, 1870)
Fig.
Clausilia insignis var. gracilior Hanley & Theobald, 1870: 12, pl. 24, fig. 3. Type locality: “Burma, Moulmain” [Mawlamyine Township, Mon State, Myanmar].
Clausilia (Phaedusa) gracilior–
Distribution. In Myanmar, this species is known from Mon State.
Remarks. Hanley and Theobald (1870) introduced this species as a variety of O. insignis but did not provide a description. Later
6 Oospira insignis (Gould, 1843)
Figs
Clausilia insignis Gould, 1843: 140. Type locality: “Tavoy, British Burma” [Dawei, Tanintharyi Region, Myanmar].
Clausilia (Phaedusa) insignis–
Oospira insignis–
Distribution. In Myanmar, this species is originally known from Dawei, Tanintharyi Region. Subsequent records were from Mon and Kayin states in Myanmar, and the range was further extended to include Tak and Kanchanaburi provinces in Thailand (
Remarks. Oospira insignis was the first clausiliid discovered from Myanmar, introduced by A.A. Gould based on specimens from the American missionary and naturalist Francis Mason (1799–1874). In the original description,
7 Oospira limborgi Grego & Szekeres, 2021
Fig.
Oospira limborgi Grego & Szekeres in
Distribution. In Myanmar, this species is known only from Tanintharyi Region.
8 Oospira malaisei Nordsieck, 1973
Figs
Oospira malaisei Nordsieck, 1973: 81, 82, pl. 3, fig. 3. Type locality: “Punkataung bei Myitkyina (3000 ft), NO-Birma” [near Punkataung, Myintkyina Township, Kachin State, Myanmar].
Distribution. This species was introduced from Kachin State, and no subsequent materials have been recorded from Myanmar. Recently, provisionally classified specimens belonging to this species were reported from Mae Hong Son Province in Thailand (
9 Oospira mongmitensis Grego & Szekeres, 2021
Fig.
Oospira mongmitensis Grego & Szekeres in
Distribution. In Myanmar, this species is only known from Shan State.
10 Oospira sardicola Grego & Szekeres, 2021
Fig.
Oospira sardicola Grego & Szekeres in
Distribution. In Myanmar, this species is only known from Shan State.
11 Oospira vespa (Gould, 1856)
Figs
Clausilia vespa Gould, 1856: 13. Type locality: “Tavoy” [Dawei, Tanintharyi Region, Myanmar].
Clausilia (Oospira) vespa–
Oospira vespa–
Distribution. In Myanmar, this species is known from Tanintharyi Region and Salween Valley (Sykes, 1893).
Remarks. Oospira vespa is the second clausiliid species introduced by
While describing Oospira stoliczkana from Myanmar,
12 Phaedusa kazueae Hunyadi & Szekeres, 2021
Fig.
Phaedusa kazueae Hunyadi & Szekeres in
Distribution. In Myanmar, this species is only known from Shan State.
13 Phaedusa lemani (Gude, 1914)
Fig.
Clausilia (Phaedusa) lemani Gude, 1914: 313, 314, fig. 107. Type locality: “Arakan, Burma” [Rakhine State, Myanmar].
Distribution. In Myanmar, this species is only known from Rakhine State and no further materials have been mentioned to date.
14 Phaedusa lypra (Mabille, 1887)
Fig.
Clausilia lypra Mabille, 1887: 117. Type locality: “Tonkin” [Vietnam].
Phaedusa (Phaedusa) lypra–
Phaedusa lypra–
Distribution. In Myanmar, this species is known from Shan State and Mandalay Region (
15 Phaedusa theobaldi (Blanford, 1872)
Fig.
Clausilia (? Medora) theobaldi Blanford, 1872: 201, pl. 9, fig. 5. Type locality: “Tonghu in provincia Barmana” [Taungoo Township, Bago Region, Myanmar].
Clausilia (Phaedusa) theobaldi–
Phaedusa theobaldi–
Distribution. In Myanmar, this species was first known from Bago Region. Later, the range was expanded records from Rakhine and Kayah States in Myanmar and from Thailand (
16 Phaedusa bocki thompsoni Grego & Szekeres, 2021
Fig.
Phaedusa bocki thompsoni Grego & Szekeres in
Distribution. In Myanmar, a single specimen was recorded in Shan State (
17 Indonenia admirabilis Grego & Szekeres, 2021
Fig.
Indonenia admirabilis Grego & Szekeres in
Distribution. In Myanmar, this species is only known from Kayah State.
18 Indonenia excellens (Nordsieck, 2002)
Fig.
Tropidauchenia (Indonenia) excellens Nordsieck, 2002a: 16, fig. 6. Type locality: “Karen Mountains, 1200–1300m” [Kayin or Kayah State, Myanmar].
Indonenia excellens–
Distribution. In Myanmar, this species is known from Kayin or Kayah States, originally given type locality was uncertain. Recently, it was reported from Shan State (
19 Indonenia masoni (Theobald, 1864)
Fig.
Clausilia masoni Theobald, 1864: 246. Type locality: “Tonghu” [Taungoo Township, Bago Region, Myanmar]. Hanley and Theobald 1870: 12, pl. 24, fig. 8.
Clausilia (? Nenia) masoni–
Clausilia (Garnieria) masoni–
Indonenia masoni–
Distribution. In Myanmar, this species is only known from Bago Region.
20 Indonenia tuba (Hanley, 1868)
Fig.
Clausilia tuba Hanley, 1868: 343. Type locality: “Shan, province” [Shan State, Myanmar]. Hanley and Theobald 1870: 12, pl. 24, fig. 9.
Clausilia (Garnieria) tuba–
Indonenia tuba–
Distribution. In Myanmar, this species is known from Shan State and the Upper Salween Valley (
The senior author is grateful to all members of the Animal Systematics Research Unit (ASRU), Chulalongkorn University for their kind help during field trips in Myanmar. The authors are indebted to AJ Baldinger (