Bulimus gracilis Hutton, 1834, by original designation.

Shell slender and conical; spire high and gradually attenuated; embryonic whorls pointed and smooth; subsequent whorls with striations. Aperture vertical, broad, and oblong; columella straight, and columellar margin expanded near umbilicus. Penis long, fusiform shape at base then narrowing towards epiphallus, and flagellum absent; vagina cylindrical and narrow tube, and ~ 1/2 of penis length.

The genus is sometimes confused with Paropeas Pilsbry, 1906 and Opeas Albers, 1850. Allopeas can be distinguished from Paropeas by its less turreted shell, finner striations, smooth embryonic whorls, straight columella, and columellar margin expanded (Table 2). Paropeas possesses a mostly turreted shell, stronger irregular striations throughout and entire whorls, concave columella, and columellar margin less expanded. Additionally, Allopeas can be differentiated from Opeas by having larger and broader shell, attenuated spire, and stronger striations (Schileyko 1999). By contrast, Opeas has a smaller and narrower shell, cylindrical or less attenuated spire, and finer striations (Pilsbry 1906).

The genus Allopeas consists of ~ 25 species distributed across tropical regions of Asia, Europe, Africa, and America (Schileyko 1999; MolluscaBase 2023). In Southeast Asia, Vietnam has recorded four species (Schileyko 2011), while Cambodia, Laos, Myanmar, and Thailand have reported only one species, namely Allopeas gracile (Gude 1914; Inkhavilay et al. 2019; Sutcharit et al. 2020b).

Lectotype NHMUK 1856.9.15.68/1 (Fig. 3A) ex. Hutton collection from Mirzapore, designated in Raheem et al. (2014: 118). Paralectotypes NHMUK 1856.9.15.68/2–11 (10 shells; Fig. 3B).

Limestone hills (Apache Cement Factory), Pyinyaung Village, Meiktila District, Mandalay Region, Myanmar (20°49'39.1"N, 96°23'35.1"E): CUMZ 13066 (8 shells; Fig. 3C, D).

Figure 3. 

A–D Allopeas gracile A lectotype NHMUK 1856.09.15.68/1 from Mirzapore B paralectotypes NHMUK 1856.09.15.68/2–11 and C, D specimen CUMZ 13066 from Mandalay Region, Myanmar with embryonic whorls and aperture E–H Bacillum obtusum E, F syntype NHMUK 1906.2.2.349 from Bhamo, Upper Burmah G, H specimen NHMUK 1903.7.1.1725 from Bhamo, Upper Burma and H juvenile shell with last whorl I Bacillum theobaldi, syntype NHMUK 1912.4.16.121 from Burmah with last whorl.

Shell conically elongated, narrow, translucent, glossy, pale yellowish colour, and with 7½–8 whorls. Apex blunt; protoconch ~ 2 whorls and smooth; subsequent whorls with obliquely more or less fine and crowded riblets. Spire gradually tapering; whorls flatly convex; suture wide and shallow; last whorl largest. Aperture high and oblong shape; peristome thin and columellar margin near umbilicus is little expanded; columella straight. Umbilicus narrowly opened.

Allopeas gracile is distributed worldwide in America, Africa, Europe, and Asia (Gude 1914; Horsák et al. 2020). In South Asia, it has been reported from India, Pakistan, Sri Lanka, Nepal, and all countries in Southeast Asia (van Benthem Jutting 1952; Panha 1998; Schileyko 2011; Do and Do 2014; Raheem et al. 2014; Budha et al. 2015; Foon et al. 2017; Inkhavilay et al. 2019; Nurinsiyah and Hausdorf 2019; Sutcharit et al. 2020b).

This species was previously reported in Myanmar from several localities, including Kayin State, Mon State, Kachin State, Rakhine State, Yangon Region, and Bago Region (see Gude 1914) and presently in the Mandalay Region.

Our material from the Mandalay Region matches well with the type specimen of this species. Allopeas gracile is a globally distributed alien species introduced to numerous countries and exhibits significant variability in both size and shape, influenced by its expansive distribution range. This species is commonly found in public parks, irrigation areas, greenhouse environments, and residential campuses (Pilsbry 1906; Neubert and Bochud 2020; Kalita 2022).

Achatina cassiaca Reeve, 1849a, subsequent designation by Pilsbry (1906: 1).

Shell slender and conical in shape; spire high, turreted, and gradually attenuated; embryonic whorls cylindrically rounded, and with or without radial striations; subsequent whorls with equally spaced thick or fine radial striations. Aperture oblique and narrowly ovate; columella concave and truncated, and columellar margin simple or slightly expanded.

Bacillum can be differentiated from Allopeas in being cylindrically rounded and with striations on the embryonic whorls, whilst the columella is concave and truncated (Pilsbry 1906; Schileyko 1999). While Allopeas has a narrowly attenuated and smooth embryonic whorls, columella straight, and columellar margin near umbilicus expanded (Table 2).

At present, this genus contains seven species mainly distributed in India, and among these, two species are known from Myanmar (Blanford 1869; Pilsbry 1906; Gude 1914; Ramakrishna et al. 2010; MolluscaBase 2023). All Bacillum species are known only from shell morphology, and none of the reproductive anatomy has been published so far. Godwin-Austen (1920) stated, ‘…extended knowledge of the animals of Bacillum and Glessula shows that the two genera come next each other…’, which suggests Godwin-Austen had dissected Bacillum, but his findings were never published.

Syntypes NHMUK 1906.2.2.349 [re-registered in error as 19850143] (4 shells; Fig. 3E, F) ex. Blanford collection from Bhamo, Upper Burmah.

NHMUK 1903.7.1.1725 (2 shells + 1 juvenile; Fig. 3G, H) ex. Godwin-Austen collection from Bhamo, Upper Burma. NHMUK 18/88.12.4.1012–1014 (3 shells) from Bhamo. NHMUK (1 shell) ex. TV Oldham collection from Bhamo, Burma. SMF 145947/2 (2 shells) ex. von Möllendorff collection from Bhamo.

Shell slender, elongate turreted and apical whorls rapidly attenuated; apex rounded, blunt and very large embryonic shell; subsequent whorls with fine radial striae. Suture shallow and whorls flattened. Aperture obliquely subovate; columella curved and truncated.

This species is known only from the type locality.

No new material of this species was collected in this study, but the syntypes are illustrated for the first time.

NHMUK 1912.4.16.121 (1 shell; Fig. 3G) ex. Beddome collection from Burmah.

Shell elongate turreted and gradually attenuated; apex rounded, blunt and very large embryonic shell; subsequent whorls with strong and equally spaced radial ribs throughout. Aperture ovate; columella curved and truncated.

This species was recorded from near the Salween River and in Shan State, Myanmar (Hanley and Theobald 1870; Pilsbry 1906). The additional report from ‘India’ by Ramakrishna et al. (2010) is possibly erroneous.

No new material of this species was examined. Bacillum theobaldi was initially proposed without a proper description other than comparing it with B. cassiacum (Reeve, 1849a) and with an imprecise type locality noted as ‘Near the Salwen’ (Hanley and Theobald 1870). Pilsbry (1906) confined the type locality as near to the Salween River in Shan State.

This species is superficially similar to B. obtusum in shell shape. However, B. theobaldi has equally spaced radial ridges (Fig. 3I), whereas B. obtusum processes finer radial striations (Fig. 3H).

Curvella sulcata Chaper, 1885, by original designation in Chaper (1885: 48).

Shell oblong-conical; spire low or high and rapidly attenuated; embryonic whorls smooth; subsequent whorls with equally or irregularly spaced thick or fine radial striations or ribs. Aperture vertical, broad-ovate, or oblong, and somewhat pointed above; columella straight; columellar margin expanded near umbilicus. Penis simple and short papillate or short tube; epiphallus and flagellum absent; vagina large, muscular, and nearly equal to penis length.

Curvella is clearly distinct from other subulinid genera such as Allopeas, Bacillum, and Opeas by its oblong-conical shell, short spire, high and wide aperture, and its much broader last whorls (Table 2). Regarding the genitalia, this genus displays a more rounded, muscular, short penis and a thicker vagina than Allopeas and Opeas (Schileyko 1999). In comparison, the two latter genera have a slender, narrow, more elongated penis and vagina compared to Curvella (Schileyko 1999; Budha 2017). However, only genitalia of Curvella sikkimensis (Reeve, 1850) is known for this genus at present (Budha 2017).

This genus is widely distributed from Africa to South Asia and China, and ~ 95 species have been reported (Pilsbry 1906; Gude 1914; Schileyko 1999; Ramakrishna et al. 2010; Budha et al. 2017; MolluscaBase 2023). There are scattered reports of four Curvella species in Myanmar, while one species, C. tonkiniana Jaeckel, 1950, has been reported in Vietnam and one species, C. jousseaumei (de Morgan, 1885), from Peninsular Malaysia (Gude 1914; Maassen 2001; Schileyko 2011; Vermeulen et al. 2015).

Syntypes NHMUK 1906.2.2.235 (2 shells; Fig. 4A) ex. Blanford collection from Thyetmyo, Pegu? Akouktoung.

Figure 4. 

A Curvella plicifera, possible syntype NHMUK 1906.2.2.235 from Thyetmyo, Pegu; Akouktoung B, C Curvella pusilla B possible syntype NHMUK 1906.2.2.234 from Akouktong, Pegu and C specimen NHMUK 1888.12.4.1003–1004 from Pegu D, E Curvella puta D holotype UMZC I.102795 from Tavoy, Birmah (after Preece et al. 2022: fig. 55f) and E specimen NHMUK 1888.12.4.1003–1004 from Pegu F Curvella scrobiculata, possible syntype NHMUK 1906.2.2.226 from Akouktong, Pegu.

Shell ovate conic; spire low; apex bluntly obtuse; subsequent whorls with prominent growth lines throughout. Suture shallow and whorls flattened. Aperture broadly ovate and somewhat pointed posteriorly; columella straight and expanded; parietal callus thin and with small parietal lamella. Umbilicus narrow.

This species is restricted to Myanmar and is known only from the type locality.

No new material of this species was found in this study, and only the available syntypes are examined here. The modern name of the type locality is Thayet District, Magway Region, central Myanmar [not in the Bago Region].

Among the four Curvella species from Myanmar, this species is similar to C. pusilla (Blanford, 1865) in shell shape. However, C. plicifera has a small parietal tooth, straight columella, and narrowly opened umbilicus, whereas C. pusilla possesses a smooth parietal wall (without tooth), slightly twisted columella plait, and closed umbilicus. Further confirmation from additional specimens is necessary to verify their distinctions.

Possible syntypes NHMUK 1906.2.2.234 (2 shells; Fig. 4B) ex. Blanford collection from Akouktong, Pegu.

NHMUK 1888.12.4.1003–1004 (1 shell identified as C. pusilla; Fig. 4C [another shell identified as C. puta]) ex. W. Theobald collection from Pegu.

Shell ovate conic; spire low; apex bluntly obtuse; subsequent whorls with prominent growth lines. Suture shallow and whorls slightly flattened. Aperture broadly ovate and pointed posteriorly; columella twisted and expanded; parietal callus thin. Umbilicus closed.

This species seems restricted to Myanmar and is known only from the type locality. The modern administrations of the type locality are ‘Prome district’ [Pyay District] and ‘Pegu’ [Bago Region].

No new material of this species was found in this study, and only the probable syntypes were examined. These are considered possible syntype material since the locality data (Akouktong, Pegu) does not precisely match that which was given in the original description (Prome district, Pegu).

Blanford (1865) noted that C. pusilla resembles the young specimen of C. puta (Benson, 1857), but this species has a closed umbilicus, while C. puta possesses an opened umbilicus. We recognise C. pusilla as a valid species following Blanford’s description, and no new materials of this species were examined in this study.

Holotype UMZC I.102795 (Fig. 4D; after Preece et al. 2022: fig. 55f) ex. R. McAndrew ex. Benson collection from Tavoy, Birmah.

NHMUK 1888.12.4.1003–1004 (1 shell identified as C. puta; Fig. 4E [another shell identified as C. pusilla]) ex. W. Theobald collection from Pegu. NHMUK 1906.1.1.1033 (1 shell) ex. Godwin-Austen collection from Bassein, Pegu.

Shell conical; spire high; apex obtuse; subsequent whorls with strong and prominent growth lines. Suture impressed and whorls slightly convex. Aperture semi-ovate and somewhat pointed above; columella straight and dilate; parietal callus thin. Umbilicus narrow.

This species was reported from the Tanintharyi and Bago regions of Myanmar and Thailand (Blanford 1865; Gude 1914; Panha 1998).

Curvella puta was described based on a single bleached specimen collected from ‘Tavoy’ in Myanmar. No new material of this species was found during this survey, but the type specimens and authenticated museum specimens are illustrated herein.

There is a mixed-species lot, NHMUK 1888.12.4.1003–1004, ex. the W. Theobald collection, labelled ‘Hapalus putus Benson’ from ‘Pegu’, consisting of two shells. The first shell (Fig. 4E) has a high, turreted, and pointed spire, narrowly opened umbilicus, and strong radial striations, which agree with the holotype of C. puta from ‘Tavoy’ (Fig. 4D). The other shell (Fig. 4C) has a lower and convex spire, fine radial striations, narrowly opened umbilicus, and without a parietal tooth, which more resembles C. pusilla. In comparison, C. pusilla possesses a closed umbilicus without a parietal tooth (Fig. 4B), while C. plicifera has an open umbilicus and a small parietal tooth (Fig. 4A).

This mixed-species lot suggests several interpretations: i) an extended distribution of C. puta beyond its type locality to the Bago Region in central Myanmar, and ii) the presence or absence of a parietal tooth and an open or closed umbilicus are possibly intraspecific variation rather than diagnostic characters distinguishing between C. plicifera and C. pusilla. Additional evidence and further specimens from a wider geographic range will clarify this issue.

Possible syntypes NHMUK 1906.2.2.226 (2 shells; Fig. 4F) ex. Blanford collection from Akouktong, Pegu.

Shell conical; spire high; apex obtuse; subsequent whorls with strong and equally spaced radial ridges throughout. Suture impressed and whorls flattened convex. Aperture truncate and somewhat pointed posteriorly; columella straight and thickened; parietal callus thin. Umbilicus narrowly open.

This species is known only from the type locality and is probably an endemic species in Myanmar.

No new material of this species was found in this study, and the probably syntype is illustrated here for the first time. Blanford (1865) described three Curvella species, C. plicifera, C. pusilla, and C. scrobiculata, from Myanmar consecutively in the same publication with their type localities as ‘Pegu’ [now in the Bago Region]. Compared to the authenticated museum specimens, C. scrobiculata is distinct from C. puta by having strong radial ribs, flatter whorls, and a more turreted, pointed, and higher spire. Furthermore, C. scrobiculata is easily distinguishable from C. plicifera and C. pusilla by its higher, pointed, turreted spire and prominent radial ribs. In contrast, the two latter species exhibit a lower and more convex spire with finer radial striations to nearly smooth shell surfaces. These are considered possible syntype material since the locality data (Akouktong, Pegu) does not exactly match that which was given in the original description (Pegu, west of Irawady).

Achatina gemma Reeve, 1850 by original designation.

Shell ovate-conical in shape; spire low or high conical, and regularly attenuated; embryonic whorls smooth or with striations; subsequent whorls with equally or irregularly spaced radial striations or ribs. Aperture oblique, narrow to wide, and ovate; columella concave and truncated, and columellar margin not expanded. Penis large, thick, and moderately long; epiphallus short, stout, terminally pointed, and curved; flagellum present (rarely absent) with comb-like or hand-like structures; epiphallic caecum absent; vagina muscularly and nearly equal to ~ 1/5–2/5 of penis length.

Superficially, Glessula and Rishetia are similar in having a concave and truncated columella, but they differ in their shell shape and genital structure (Godwin-Austen 1920; Raheem et al. 2014; Budha et al. 2017). In terms of shell morphology, Glessula can be differentiated by its ovate-conical shape, short spire, large and blunt embryonic whorls, while Rishetia possesses a slender, conical-shaped elongate spire which narrow and rather acute embryonic whorls (Table 2). Regarding the genital characters, Rishetia exhibits a simple, tubular-shaped flagellum with the epiphallic caecum present (Table 3), while Glessula displays a well-developed comb-like flagellum (appendage) and the epiphallic caecum absent (Budha et al. 2017); except G. mandalayensis sp. nov. which has no flagellum. Likewise, Glessula is also distinct from Curvella by its concave and truncated columella, not expanded columellar margin, and obliquely narrow and ovate aperture, while Curvella possesses a straight columella, expanded columellar margin, and more vertical, higher, and broader oblong aperture.

Glessula is widely distributed throughout the Indian subcontinent, and nearly 100 species have been described (Godwin-Austen 1920; Schileyko 1999; Ramakrishna et al. 2010; MolluscaBase 2023). Among the sporadic species recorded in Southeast Asia, Myanmar has 12 species (Gude 1914; Godwin-Austen 1920), while two species, G. latestriata von Möllendorff, 1899 and G. paviei Morlet 1893, have been recorded from Vietnam, Laos, and Thailand, and another two species, G. sumatrana (von Martens, 1864) and G. wallacei (Pfeiffer, 1856) from Indonesia (Tenison-Woods 1888; van Benthem Jutting 1952; Solem 1966; Schileyko 2011; Inkhavilay et al. 2019).

In this study, only five species including a new species, G. blanfordiana Nevill, 1877, G. feddeni Godwin-Austen, 1920, G. gemma (Reeve, 1850), G. latestriata, and G. mandalayensis sp. nov. have been collected and re-described.

Syntypes NHMUK 1988150 (2 shells; Fig. 5A, B) ex. Godwin-Austen collection from Ponsee, Yunnan, W. China.

Aik Kham Cave, Taunggyi Township, Taunggyi District, Shan State, Myanmar (20°49'07.0"N, 97°13'42.0"E): CUMZ 13067 (3 shells; Fig. 5C, D).

Figure 5. 

A–D Glessula blanfordiana A, B syntypes NHMUK 1988150 from Ponsee, Yunnan, W. China and C, D specimen CUMZ 13067 from Taunggyi, Shan State, Myanmar E, F Glessula crassilabris E syntype UMZC I.102430 from Bengal (after Preece et al. 2022: fig. 51e) and F specimen NHMUK from Cherrapoonji (M10604/2).

Shell ovately conical, solid, brownish colour, and with 6–6½ whorls. Apex rounded; protoconch ~ 2 whorls with weak radial striations; subsequent whorls with equally and widely spaced ribs, more raised, and coarser near suture of last whorl. Spire regularly attenuated, slightly turreted; whorls convex; suture deep; last whorl largest. Aperture obliquely and narrowly ovate; peristome white and thickened; columella short, concave, slightly twisted and abruptly truncated. Umbilicus closed.

This species was originally described from Yunnan, China, and subsequently reported from Bhamo, Kachin State, Myanmar (Nevill 1881). In this study, new material has been collected from Shan State, which borders Yunnan to the east and Bhamo to the north.

When nominating this species, Nevill (1877: 26) compared it with G. peguensis (Blanford, 1865) from Bago and stated that G. blanfordiana has slender (less convex) whorls, wavy or curving, and stronger radial ribs. Nevertheless, the type specimens of these two species, G. blanfordiana (height 8–9 mm, Fig. 5A, B) and G. peguensis (height ~ 7 mm, Fig. 10B, C), exhibit considerable similarity in terms of shell shape and shell size. Therefore, more specimens from the Bago Region are necessary to ascertain whether the difference in shell sculptures represents variations or are taxonomically informative characters separating these two species.

Glessula blanfordiana examined herein are noticeably distinct from their congeners recorded in Shan State and Mandalay Region, namely G. feddeni Godwin-Austen, 1920 and G. latestriata von Möllendorff, 1899. Specifically, G. blanfordiana has a shorter and bluntly attenuated spire, more bulging whorls, deeper suture, and stronger and densely radial ribbed sculptures. In contrast, the other species exhibit higher and pointed spires, more flattened whorls, and smooth to radial grooves sculptures (see Fig. 2D).

Glessula blanfordiana was described based on two specimens collected by J. Anderson during the Expedition to Yunnan and Upper Burma. The original description was very brief, without shell dimensions and illustrations. However, under the note of G. ponsiensis Godwin-Austen, 1920, states, ‘The type from Ponsee, Yunnan (Plate CLXIV. fig. 20, apex) [= G. blanfordiana], has been sent me from Calcutta by the Director of the Zoological Survey of India, Dr. N. Annandale…’ (Godwin-Austen 1920: 56). The NHMUK type collections contain a single lot with an original label stating ‘Type’ from ‘Dr. J. Anderson’, and collection locality from ‘Ponsee’. These two specimens match well with the species description; both are figured herein for the first time. It is possible that N. Annandale may have gifted this type specimen lot to Godwin-Austen for comparison with other species, as was the case with other specimens from the Zoological Survey of India.

Syntype UMZC I.102430 (1 shell; Fig. 5E after Preece et al. 2022: fig. 51e) from Bengal.

NHMUK (1 shell; Fig. 5F) from Cherrapoonji (M10604/2). NHMUK 20200349 (2 shells) from N.E. Bengal. NHMUK 20200350 (2 shells) M.10695/2 from Khasi.

Shell oblong ovate and regularly attenuated; spire high conical; apex rounded; subsequent whorls with weak and irregularly spaced radial ridges, slightly stronger near suture, and fine radial groves present. Suture impressed and whorls slightly convex. Aperture ovate; columella strong, concave, and truncated.

This species is known from India and Rakhine State, Myanmar (Godwin-Austen 1920).

The taxonomic history and clarification status of the type specimens have recently been published in Preece et al. (2022). Blanford (1865: 95) reported a small variety of Glessula crassilabris based on specimens from ‘Arakan’ [Rakhine State] and ‘Shan hills near Ava’ [Shan Hills near Innwa], and also suggested that the latter specimen lot were possibly distinct from G. crassilabris s. s., although they were closely related. The following year, Godwin-Austen (1920) introduced the Shan hills specimens as G. feddeni Godwin-Austen, 1920, but the small variety from ‘Arakan’ has never been made available.

Syntypes NHMUK 1906.2.2.261 [re-registered in error as 1985142] (5 shells; Fig. 6A, B) ex. Blanford ex. Godwin-Austen collection from the Shan Hills, E. of Ava.

NHMUK 1906.3.3.41 (1 shell; Fig. 6C) ex. Blanford ex. Fedden collection labelled as ‘var.’ from the Shan Hills. Limestone hills (Apache Cement Factory), Pyinyaung Village, Meiktila District, Mandalay Region, Myanmar (20°49'39.1"N, 96°23'35.1"E): CUMZ 13068 (8 shells; Fig. 6D–F).

Figure 6. 

A–F Glessula feddeni A, B syntypes NHMUK 1906.2.2.261 from Shan Hills, E. of Ava C specimen NHMUK 1906.3.3.41 from Shan Hills and D–F specimen CUMZ 13068 from Pyinyaung Village, Mandalay Region, Myanmar.

Shell globosely conical, solid, glossy, brownish colour, and with 6½–7 whorls. Apex slightly pointed; protoconch ~ 2 whorls with smooth surface; subsequent whorls with strong, oblique, and equally spaced radial grooves that more distinct near suture. Spire attenuated, turreted and pointed; whorls flatly convex; suture deep; last two whorls almost equal and largest. Aperture narrowly and obliquely ovate; parietal wall straight; peristome white and thickened; columella short, concave, slightly twisted, and truncated. Umbilicus closed.

This species was originally described from ‘Shan Hills’, but the precise type locality was not provided. In this study, G. feddeni was located in the Mandalay Region adjacent to the Shan Hills.

Godwin-Austen (1920) clearly states the catalogue number ‘Type No. 261.06.2.2’ (NHMUK 1906.2.2.261) from the Shan Hills. The original description included an illustration and two sets of measurements. The Godwin-Austen’s type lot in the NHMUK consists of five shells with an original handwritten label stating ‘Type’. The two specimens with the largest shell height closest to the given measurements are here illustrated together with another shell from the syntype lot.

Godwin-Austen (1920: 58, pl. 163, fig. 14) also recognised another variety as ‘var.’ and illustrated specimen lot ‘No. 41.06.3.3’ (NHMUK 1906.3.3.41). Nevertheless, this entity has never been properly made available. The specimen lot NHMUK 1906.3.3.41 (Fig. 6C) labelled as ‘var.’ is excluded from the type series of this nominal species (ICZN 1999: Art. 72.4.1). However, this specimen has a more slender shell than the type series (Fig. 6A, B) and is possibly more closely related to G. latestriata, which is also distributed in the Shan State.

The type specimen could not be located in the UMZC nor in the NHMUK collections (Raheem et al. 2014; Preece et al. 2022).

NHMUK 1946.10.16.45–53 (9 shells; Fig. 7A, B) ex. Benson collection from Bengal. Montawa Cave, Taunggyi City, Taunggyi District, Shan State, Myanmar. (20°45'15.9"N, 97°1'3.4"E): CUMZ 13069 (5 shells; Fig. 7C, D).

Figure 7. 

A–D Glessula gemma A, B specimen NHMUK 1946.10.16.45–53 from Bengal and C, D specimen CUMZ 13069 from Taunggyi, Shan State, Myanmar E, F Glessula inedita, syntypes NHMUK 1906.5.5.88 from Shan Hills.

Shell elongate ovate, solid, purple-black or yellowish colour, and with 6½–7 whorls. Apex blunt; protoconch ~ 2 whorls with smooth surface; subsequent whorls with smooth and glossy to weakly radial ribs. Spire grows evenly, is high and obtuse; whorls flatly convex; suture wide and shallow; last two whorls almost equal and largest. Aperture obliquely ovate; peristome moderately thickened and white; columella short, concave, and truncated. Umbilicus closed.

Glessula gemma was originally described from India and then its range extended to Bangladesh (Gude 1914; Godwin-Austen 1920; Raheem et al. 2014). In Myanmar, this species has been recorded from the Rakhine State and now in the Shan State.

The historical specimens NHMUK 1946.10.16.45–53 ex. Benson collection from Bengal is illustrated herein as an example.

Our specimens match well with the authenticated Reeve specimen of this species, although it is far from the type locality and previously reported region in the Rakhine State, Myanmar. Among all the Glessula species from Myanmar, G. gemma is superficially similar to G. latestriata from Shan State. In comparison, G. gemma has smooth shell surfaces, less turreted spire, and a shallow suture, while G. latestriata possesses well-developed grooves, a turreted and more attenuated spire, and a deeper suture.

Syntypes NHMUK 1906.5.5.88 [re-registered in error as 1985228] (3 shells; Fig. 7E, F) ex. W.T. Blanford collection from Shan Hills.

Shell oblong turreted and regularly attenuated; spire high conical; apex rounded; subsequent whorls with very weak irregularly spaced radial ribs. Suture deep and whorls convex. Aperture widely ovate; columella concave and truncated.

This species is known to occur only from the type locality.

The original description did not include an illustration, and one set of shell measurements was given. Godwin-Austen (1920: 58) clearly states, ‘Type No. 88.06.5.5’ (NHMUK 1906.5.5.88) is from the Blanford collection. This syntype lot consists of three shells, and the original label states ‘Type’. The largest specimen matches well with the given measurements, and another shell from the same syntype lot is illustrated herein for the first time. No new materials have been reported to date.

Lectotype SMF 145919/1 (Fig. 8A) designated in Zilch (1973: pl. 5, fig. 26) from Kalow, Shan States. Paralectotypes SMF 227513/2 (2 shells) and NHMUK 1926.2.3.19–20 (2 shells; Fig. 8B) from Kalow, Shan States.

Figure 8. 

A–D Glessula latestriata A lectotype SMF 145919 from Kalow, Shan States B paralectotypes NHMUK 1926.2.3.19–20 from Kalow, Shan States C specimen CUMZ 13070 from Thale Cumon Temple, Kalaw, Shan State, Myanmar and D specimen CUMZ 13071 from Ywangan Village, Kalaw, Shan State, Myanmar E, F Glessula mandalayensis sp. nov. E holotype CUMZ 13072 from Pyinyaung Village, Mandalay Region, Myanmar and F paratypes CUMZ 13073 from the type locality. Photograph: Gojšina & Páll-Gergely (A).

Thale Cumon Temple, Kalaw City, Shan State, Myanmar (20°43'24.1"N, 96°35'38.9"E): CUMZ 13070 (3 shells; Fig. 8C). Ywangan Village, near Lin Way Monastery, Kalaw Township, Taunggyi District, Shan State, Myanmar (21°13'43.3"N, 96°33'19.2"E): CUMZ 13071 (1 shell; Fig. 8D).

Shell ovate conic, solid, glossy, brownish colour, and with 6½–7 whorls. Apex blunt; protoconch ~ 2 whorls with smooth to shallow radial grooves; subsequent whorls with distinctly thickened and equally spaced grooves. Spire gradually attenuated, slightly turreted, and bluntly pointed; whorls convex; suture deep; last two whorls almost equal and largest. Aperture narrow and obliquely ovate; peristome white and thickened; columella short, concave, slightly twisted, and truncated. Umbilicus closed.

This species is known from Shan State in Myanmar, northern Thailand, and Laos (Gude 1914; Solem 1966; Inkhavilay et al. 2019).

von Möllendorff (1899) described this species based on specimens collected by B Strubell from Shan State, Myanmar. The original description did not include any illustrations, and only one set of measurements was given. The species description was not explicitly based on one specimen. Nevertheless, Zilch (1973: 110) later used the terms ‘Holotypus SMF 145919’ and ‘Paratypen SMF 227513/2’ for the von Möllendorff type series in the SMF collection. This is not a valid holotype designation, but we consider it an inadvertent lectotype designation (ICZN 1999: Arts. 73.1, 74.5, and Recommendation 73F). The other specimens labelled as ‘Paratypen SMF 227513/2’ and ‘Co-types NHMUK 1926.2.3.19–20’ are considered paralectotypes.

Although both G. latestriata and G. feddeni possess radial grooves striations, the former has a slender shell, gradually attenuated spire, and blunter apex; in contrast, G. feddeni has a larger and broader shell, turreted, intermediately attenuated spire and pointed apex with abruptly truncate columella.

Holotype CUMZ 13072 (height 14.6 mm, width 7.1 mm; Fig. 8E), paratypes CUMZ 13073 (29 shells; Fig. 8F), NHMUK 20230922 (2 shells) and SMF (2 shells).

Limestone Hills (Apache Cement Factory), Pyinyaung Village, Meiktila District, Mandalay Region, Myanmar (20°49'39.1"N, 96°23'35.1"E).

The specific name mandalayensis is the name of region, where the type specimens of this species were collected.

Shell large, globosely ovate; spire broad, almost cylindrically attenuated, turreted; last whorl largest; shell surface glossy, smooth to shallow grooves; aperture ovately rounded and broad; peristome thin and white.

Shell globosely ovate, solid, glossy, brown to bright ochraceous colour, and with 6–7 whorls. Apex blunt and large; protoconch ~ 2 whorls with smooth surface; subsequent whorls with smooth to fine radial striations or sometimes with shallow grooves. Spire broad, cylindrically attenuated, turreted; whorls flatly convex; suture deep; last whorl largest. Aperture ovately rounded and broad; peristome white and thin; columella short, concave, and truncated. Umbilicus closed.

Genitalia (n = 1). Atrium very short. Penis evenly broad, stout, and thick muscularly. Epiphallus short, stout, slightly curved triangular shape, thick muscularly, smooth surface, and ~ 1/4 of penis length; flagellum absent. Penial retractor muscle long, thickened and attaches laterally at junction of penis and epiphallus. Vas deferens long distinct tube connected between tip of epiphallus and free oviduct and held in position to penis and vagina with weak connective tissue (Fig. 9A).

Figure 9. 

Genitalia and radula of Glessula mandalayensis sp. nov., paratype CUMZ 13073 from Pyinyaung Village, Mandalay Region, Myanmar A reproductive anatomy and B radula morphology: yellow colour and ‘C’ indicates central teeth row and numbers indicate tooth order from lateral to marginal end. Abbreviations: at, atrium; ep, epiphallus; fo, free oviduct; gd, gametolytic duct; gs, gametolytic sac; p, penis; pr, penial retractor muscle; so, spermoviduct; v, vagina; vd, vas deferens.

Vagina muscularly and nearly as long as penis. Gametolytic duct short and enlarged at base; gametolytic sac small and elliptical in shape. Free oviduct short and stout, and spermoviduct enlarged.

Radula. Each row contains ~ 70+ teeth with half-row formula: central-lateral-marginal teeth (1–(19–20)–(15–16+)). Central tooth relatively small, symmetrical tricuspid with pointed central cusp and very small lateral cusps. Lateral teeth bicuspid: endocone long, slender and with pointed tip; ectocone small, pointed tip and located at base of teeth. Latero-marginal teeth gradually reduced in size and asymmetrically bicuspid: endocone short with pointed tip; ectocone small triangle on shape and situated around middle of tooth height. Outermost teeth small and becoming tricuspid; mesocone short and blunt tip; endocone and ectocone very small and pointed tips (Fig. 9B).

This new species is known only from the type locality.

Glessula mandalayensis sp. nov. can be distinguished from other congeners in Myanmar by having the largest and most globosely ovate shell, obtuse and broad spire, wide aperture, and thinner peristome. In particular, this new species differs from a sympatric species, G. feddeni, by having a larger size (height 13.3–16.0 mm; Table 1), more rounded shell, obtuse and broader turreted spire, wider aperture, thinner peristome, and smoother shell surface. In comparison, G. feddeni is smaller in size (height 7.8–10.8 mm; Table 1), with a more solid, slender conical shell, pointed and narrow spire, smaller aperture, thicker peristome, and with distinct grooves on the shell surface. Glessula mandalayensis sp. nov. can also be separated from G. latestriata by its broader shell, wider spire, and blunt apex with smoother shell surface. Whereas G. latestriata has a slenderer shell, narrowly attenuated spire and pointed apex with distinct radial grooves striations. This new species also differs from G. gemma by having a larger and globosely ovate shell (height 13.3–16.0; Table 1), more turreted spire, convex whorls, vertically elongated aperture, and deeper suture. Whereas G. gemma possesses a smaller and slender shell (height 8.7–9.2; Table 1), spire high conical, flatly convex whorls, more rounded aperture, and shallow suture.

Additionally, this new species differs from G. crassilabris s. s. from India and its variety from Rakhine State, Myanmar, in having a smoother shell, obtuse, and lower and broader spire. While G. crassilabris s. s. (Fig. 5E, F) displays stronger striations and a narrowly pointed spire (Blanford 1865).

So far, the genitalia of eight Glessula species has. The terminal part of the male genitalia of G. mandalayensis sp. nov. (Fig. 9A) clearly differs from these eight species in having no flagellum, while a flagellum is well-developed with a comb-like shape in the others (Table 3). However, we examined only a single specimen; therefore, the extent of variability within the species remains unknown.

The type specimen could not be located from the UMZC and the NHMUK collections (Raheem et al. 2014; Preece et al. 2022).

NHMUK (3 shells + 2 juveniles; Fig. 10A) ex. Blanford collection from Mahableshwar.

Figure 10. 

A Glessula orophila, specimen NHMUK ex. Blanford collection from Mahableshwar B, C Glessula peguensis, specimen NHMUK 1909.3.15.8 from Thyet-Myo D, E Glessula perlevis, syntypes NHMUK 1906.5.5.89 from Shan Hills, Burma F Glessula ponsiensis, syntypes NHMUK 1989042 from Ponsee.

Shell ovate conical and regularly attenuated; spire low conical; apex rounded; subsequent whorls with very weak irregularly spaced radial ridges, and fine radial groves present. Suture shallow and whorls flattened. Last whorl large and ovate; aperture ovate; columella concave and truncated.

This species was first introduced from India and later reported from Sri Lanka and Pegu [Bago Region, Myanmar] (Gude 1914: 423).

Glessula orophila is listed in the doubtful name by Raheem et al. (2014). No Myanmar material has been examined, and only the literature record is known.

The type specimen could not be located in the NHMUK collection.

NHMUK 1909.3.15.8 (3 shells; Fig. 10B, C) ex. Blanford collection from Thyet-Myo. NHMUK 20230920 ex. H.B.F. collection (4 shells) from Thyet Myo. SMF 235657/2 (2 shells) from Pegu.

Shell oblong ovate and regularly attenuated; spire high conical; apex rounded and blunt; subsequent whorls with prominent regularly spaced radial ribs. Suture deeply impressed and whorls convex. Aperture widely ovate; columella strong, concave, and truncated.

Glessula peguensis is distributed in Bago Region, Magway Region, and Rakhine State in Myanmar, as well as in Chittagong, Bangladesh (Gude 1914; Godwin-Austen 1920).

The specimen from ‘Thyet-myo’, which is present in the Blanford collection with the original label as ‘authentic’, is illustrated herein as an example of this species. According to Godwin-Austen (1920: 56), this species is commonly found in Pegu.

The original type locality of this species was from a broad geographical range, ‘Pegu’, and the museum label stated Thyet-Myo as the collection locality. The reference to ‘Pegu’ and ‘Thyet-Myo’ on the original label needs to be clarified as to whether they refer to the same area or if there is a specific location in ‘Thyet-Myo, Pegu’. The current administration area now includes ‘Thyet-Myo’ [Thayet Myo] as a district of the Magway Region located in central Myanmar, formerly part of ‘Pegu, Lower Burma’ during the British colonial period. Furthermore, Godwin-Austen (1920: 56) stated that additional specimens from ‘Arakan near Tongoop’ (No. 262.06.2.2) tended to have a larger shell size than the type specimen.

Syntypes NHMUK 1906.5.5.89 [re-registered in error as 1986023] (5 shells; Fig. 10D, E) ex. Godwin-Austen collection from Shan Hills, Burma.

Shell oblong ovate and regularly attenuated; spire high conical; apex rounded and blunt; subsequent whorls nearly smooth with very weak growth lines, and somewhat strong irregularly spaced ridges near suture. Suture impressed and whorls slightly convex. Aperture ovate; columella concave and truncated.

This species is known only from the type locality in the Shan Hills near Mandalay. The type locality noted by Godwin-Austen seems ambiguous because it was described as ‘probably comes from the Shan State near Mandalay collected by Fedden’ (Godwin-Austen, 1920: 59).

Godwin-Austen (1920) described this species based on five specimens in the Blanford collection. The species description included one set of shell measurements, the number of specimens examined and the W.T. Blanford catalogue number ‘Type No. 89.06.5.5’ (NHMUK 1906.5.5.89), and there was no illustration of the shell. The NHMUK collections contain a type specimen lot consisting of five shells (2 matures + 3 immatures) with an original label stating ‘Types’. The mature shells correspond well with the shell dimensions given in the original description and are illustrated herein for the first time.

Syntypes NHMUK 1989042 (1 shell; Fig. 10F) and NHMUK 1989043 (3 shells; Fig. 11A), both specimen lots collected by J. Anderson from Ponsee.

NHMUK 1912.4.16.747 (2 shells; Fig. 11B) ex. Beddome collection from Ponsee, Yunnan.

Figure 11. 

A, B Glessula ponsiensis A syntypes NHMUK 1989043 from Ponsee and B specimen NHMUK 1912.4.16.747 from Ponsee, Yunnan C–E Glessula woodthorpei, syntypes NHMUK 1903.7.1.1628 from Shan States F Glessula yuangensis, holotype NHMUK 1903.7.1.1312 from Yuang Ha, Shan States.

Shell oblong turreted and regularly attenuated; spire high conical; apex rounded and blunt; subsequent whorls nearly smooth with fine growth lines, and strong, equally spaced radial ridges near suture. Suture impressed and whorls slightly convex. Aperture ovate; columella strong, concave, and truncated.

Glessula ponsiensis was first described from Ponsee, Yunnan, and later discovered in Bhamao, Kachin State, situated on the upper part of Ayeyarwady River.

The original description included a set of shell measurements and an illustration of the apex. Godwin-Austen (1920: 56) clearly states that this species was described based on specimens from the Indian Museum collection (now Zoological Survey of India (ZSI), Kolkata) collected by J. Anderson from Ponsee, which was misidentified as ‘Stenogyra (Glessula) pyramis Bs., var. major Nevill, 1878’. The name ‘ var. major’ by Nevill (1878: 169) is unavailable (ICZN 1999: Art. 12). Under the note of the species, Godwin-Austen states, ‘I am fortunate in getting the type-shells for examination’. It seemed that he received on loan the type specimen (or specimens that were examined by Nevill (1878: 169)). The NHMUK type collections contain a specimen lot with two registration numbers, M10905/2 and 10906/2, which are ex-Indian Museum collection numbers where the original label states ‘Stenogyra (Glessula) pyramis Benson, var. major’, collection of ‘Dr. J. Anderson’ and with collection locality from ‘Ponsee’. Interestingly, a species-group name was struck through and rewritten with red ink by Godwin-Austen, handwritten as ‘ponsiensis, G-A.’ and with ‘Type and three other one takes for B.M.’. It is probable that these specimens were presented to Godwin-Austen for examination. The specimen NHMUK 1989042 (1 shell has blue wool inside the shell; Fig. 10F) has a subsequent label stating ‘holotype’, and NHMUK 1989043 (3 shells; Fig. 11A) originates from the same Nevill type lot and has a subsequent label stating ‘paratypes’. This is not a valid holotype designation (ICZN 1999: Arts 73.1, 73.2 and Recommendation 73F) and these specimens are considered as the syntypes, illustrated herein for the first time.

Syntypes NHMUK 1903.7.1.1628 [re-registered in error as 1986051] (9 shells; Fig. 11C–E) collected by Woodthorpe ex. Godwin-Austen collection from Shan States.

NHMUK 1903.7.1.3655 (2 shells) collected by Woodthorpe ex. Godwin-Austen collection from Siam N.W. Boundary.

Shell oblong conical and regularly attenuated; spire high conical; embryonic whorls rounded; subsequent whorls nearly smooth and equally spaced radial ridges appeared near suture. Suture impressed and whorls slightly convex. Aperture ovate; columella strong, concave, and truncated.

This species is known from Shan State, Myanmar with an additional record from Thailand.

Godwin-Austen (1920) indicated that nine specimens with the catalogue number ‘Type No. 1682 B.M.’ were examined. The species description included one set of measurements and an illustration of one shell. The NHMUK type collections contain a lot of nine specimens from the Woodthorpe collection with a label in Godwin-Austen’s handwriting stating ‘Type’. The measurements of the specimen with red wool inside the shell are close to the measurements given in the original description. It likely corresponds to the illustration of the species provided in the original description and it herein figured (Fig. 11C) along with other shells (Fig. 11D, E) from the same syntype lot.

Godwin-Austen separately mentioned (1920: 58) another bleached specimen lot NHMUK 1903.7.1.3655 (2 shells) from Thailand. However, this specimen lot does not form part of the type series of this species.

Holotype NHMUK 1903.7.1.1312 [re-registered in error as 1986052] (Fig. 11F) collected by Woodthorpe ex. Godwin-Austen collection from Yuang Ha, Shan States.

Shell oblong turreted and regularly attenuated; spire high conical; apex rounded and blunt; subsequent whorls with prominent wide spaced radial ribs, and radial groves present. Suture impressed and whorls slightly convex. Aperture ovate; columella strong, concave, and truncated.

The species is currently known only from its type locality.

Godwin-Austen clearly stated that this species was described based on only one specimen collected by R. Woodthorpe. The description included a set of shell dimensions and a shell illustration. There is one Godwin-Austen specimen lot, NHMUK 1903.7.1.1312, that has an original label stating ‘Type’ and is from the Woodthorpe collection. We recognise this specimen as the holotype fixed by monotypy. Additionally, Godwin-Austen seemed to consider another specimen lot, ‘No. 1156 B.M.’ (NHMUK 1903.7.1.1156) from Kentung State [Kengtung Township, Shan State], as a distinct entity and it is therefore excluded from the type series.

Originally, the type locality was said to be from ‘Yuang Ha, Siam Boundary’; however, this town currently is found in the Shan State, Myanmar. The original type locality is now Mong Yawng Township, Shan State (~ 21°10'42.7"N, 100°21'24.3"E), Myanmar, with a further record from Kengtung, Shan State (Godwin-Austen 1920: 59).

Helix goodallii Miller, 1822 [junior homonym of Férussac (1821)] accepted as Opeas hannense (Rang, 1831), subsequent designation by von Martens in Albers (1860: 265).

Shell small, slender, and conical; spire high, turreted, cylindrically, and gradually attenuated; embryonic whorls smooth; subsequent whorls with fine radial striations or growth lines. Aperture vertical, narrow, oblong, columellar margin expanded, and columella straight or concave. Umbilicus narrowly opened or closed. Penis cylindrical tube with short epiphallus, and flagellum and penial sheath absent; vagina long ~ 1/2 of penis length.

Opeas and Tortaxis Pilsbry, 1906 generally resemble one another in having slender conical or cylindrical shells, nearly smooth to fine striations, and flatly convex whorls (Table 2). However, Opeas has a smaller size, straight columella, and mostly oblong aperture, whereas Tortaxis displays mostly larger size, nearly straight or slightly concave columella with a spiral fold, and more or less obliqued aperture. Likewise, Opeas is distinctly differentiated from Bacillum in that it is smaller in size, has a straight columella, fine shell sculptures and embryonic whorls which are narrowly rounded. In contrast, Bacillum exhibits a larger shell size, truncated and concave columella, stronger shell sculptures, and the embryonic whorls cylindrically rounded.

This genus is distributed in tropical and subtropical regions in Europe, Asia, Africa, and North America, and comprises nearly 200 species (Schileyko 1999; MolluscaBase 2023). In Myanmar, two species are recorded (Gude 1914).

Lectotype SMF 227532 (Fig. 12A) von Möllendorff ex. C. Roebelen from Gulf von Siam: Samui-Inseln, designated in Zilch (1973: 120). Paralectotypes SMF 145657/7 (7 shells), SMF 227533/7 (7 shells).

Phra (Buddha) Cave, Tanintharyi Region, Myanmar (11°14'01.5"N, 99°10'42.8"E): CUMZ 13074 (15 shells; Fig. 12B, C).

Figure 12. 

A–C Opeas filiforme A lectotype SMF 227532 from Gulf von Siam: Samui-Inseln B, C specimen CUMZ 13074 from Tanintharyi Region, Myanmar D Paropeas swettenhami, syntype MNHN-IM-2000-38930 from Malacca E Paropeas tchehelense, syntype MNHN-IM-2000-38932 from Pérak, Mont Tchéhèl F Paropeas terebralis, syntype NHMUK 1888.12.4.1081 from Shan States, Burma G, H Paropeas turricula G syntypes NHMUK 1859.8.1.10 from Siam and H specimen CUMZ 13076 from Tanintharyi Region, Myanmar I–L Paropeas walkeri I syntypes UMZC I.103115.A from Andaman Island (after Preece et al. 2022: fig. 56e) J specimen NHMUK 1885.2.18.13–18 from Viper Id. Andamans K specimen CUMZ 13077 from Taunggyi Township, Shan State, Myanmar with embryonic whorls and aperture and L specimen CUMZ 13078 from Kalaw Township, Shan State, Myanmar with embryonic whorls and aperture. Photographs: V Gojšina & B Páll-Gergely (A), P Bourguignon (D, E).

Shell slender and conical, translucent, whitish colour, and with 7½–8 whorls. Apex rounded; protoconch ~ 2 whorls, rounded and smooth surface; subsequent whorls generally nearly smooth with fine growth lines. Spire gradually and cylindrically tapering and largely turreted; whorls flatly convex and last whorl largest; suture deep and weakly crenulated. Aperture oblong; peristome thin; columella straight; columellar margin slightly expanded. Umbilicus narrowly opened to closed.

This species occurs in peninsular Thailand and is newly recorded from the Tanintharyi Region, southern Myanmar.

New discovered of this species were found in Tanintharyi, which borders the type locality of Thailand. The type specimen (Fig. 12A) possesses less turreted and more convex whorls than our specimens; however, this differentiation is herein considered an intraspecific variation. Compared to O. innocens Preston, 1910 from Mawlamyine, O. filiforme from Tanintharyi can generally be differentiated by its slender and more attenuated shell, slightly convex whorls, and turreted spire. However, a comprehensive examination of O. innocens specimens from the type locality is necessary to confirm this distinction.

This species is known only from the type locality.

No new specimens were found during our sampling conducted in Mawlamyine, Mon State. Furthermore, the authenticated and type specimens could not be located in the NHMUK collection, and currently, this species is known solely from the original description.

Bulimus acutissimus Mousson, 1857 by original designation.

Shell slender and conical; spire high, turreted, and gradually attenuated; embryonic and subsequent whorls with irregularly dense, fine, or coarse radial striations. Aperture oblique, narrow or broadly ovate; columella concave; columellar margin expanded or not expanded. Penial simple, relatively long, slender, epiphallus short, flagellum absent, and penial sheath present; vagina ~ 1/2 of penis length and wider than penis.

Paropeas can be distinguished from Bacillum and Rishetia by its irregularly coarse radial striations throughout the shell, less concave or straighter columella, and narrowly tapering and pointed embryonic whorls (Table 2). While Bacillum has stronger and more evenly spaced radial striations, deeper concave and truncate columella, and cylindrically tapering and obtuse embryonic whorls. Likewise, Rishetia has a glossy and smoother shell, broader whorls, more concave columella, and rounded and wider aperture (Pilsbry 1906; Gude 1914; Naggs 1994). In terms of genitalia, Rishetia is obviously distinct from Paropeas by having a tubular-shaped flagellum, while Paropeas has no flagellum (Naggs 1994; Schileyko 1999).

Paropeas and Prosopeas are very similar in terms of shell form and sculpture, but Paropeas possess stronger and more compact striations on embryonic whorls (Gude 1914; Naggs 1994). However, distinguishing between these two genera is still challenging, and precise identification requires further evidence, such as data on genitalia and molecular phylogeny.

This genus is mainly distributed in Southeast Asia. Seven recognised species are present, four are reported in Myanmar (Gude 1914; Naggs 1994; Schileyko 1999; MolluscaBase 2023).

Syntype MNHN-IM-2000-38930 (1 shell; Fig. 12D) from Malacca, G. Tchéhèl.

Shell slender, elongate turreted and rapidly attenuated; apex pointed; subsequent whorls coarse with dense and fine radial striae. Suture wide and shallow, and whorls flattened. Aperture elongate ovate; columella concave.

This species has been reported from Malaysia and Shan State, Myanmar (Naggs 1994).

de Morgan (1885) describes P. swettenhami and P. tchehelense consecutively in the same publication and from a very close geographical area within Perak State, Peninsular Malaysia. Then von Möllendorff (1891: 337) suggests ‘Stenogyra swettenhami de Morgan, 1885’ as a slight variation of P. tchehelense; therefore, some subsequent authors recognise the former as a synonym of the latter (i.e., Maassen 2001; MolluscaBase 2023). In contrast, Pilsbry (1906: 32) argues that they differ in shell shape and structure. We have examined the syntypes of both species and agree with Pilsbry (1906) that P. swettenhami (Fig. 12D) differs from P. tchehelense by having a slimmer shell, narrower aperture, cylindrical and rounded embryonic whorls. Prosopeas tchehelense (Fig. 12E) possesses a large, broad shell, wide aperture, convex, and rounded embryonic whorls.

No new materials of this species were found in this survey, and the type specimen is illustrated herein. Naggs (1994) provisionally reported the occurrence of P. swettenhami from Shan State, Myanmar. Considering the vast geographical distance between Perak and Shan State, it may be that the specimens Naggs (1994) regarded as P. swettenhami are, in fact, P. terebralis or another species. However, collecting topotypical material from Shan State, Myanmar, is necessary to confirm the existence of this species in Myanmar and the systematic relationship with P. tchehelense.

Syntype NHMUK 1888.12.4.1081 (1 shell; Fig. 12F) ex. Theobald collection from Shan States, Burma.

Shell slender, elongate turreted and rapidly attenuated; apex obtuse; subsequent whorls coarse with dense growth lines throughout. Suture wide and shallow, and whorls slightly convex. Aperture elongate ovate and narrow; columella curved; peristome little acute.

This species is only known from the type locality.

No recent material of this species was collected in this survey, and the syntype is illustrated here for the first time. Gude (1914) recognised this species as belonging to the Prosopeas, but Naggs (1994) provisionally transferred this species to the Paropeas after comparing it with the type specimen.

Paropeas terebralis can be distinguished from P. swettenhami by its broader and more rounded embryonic whorls, deeper suture and slightly convex whorls, and coarse shell surface with dense growth lines. Whereas P. swettenhami possesses narrower and pointed embryonic whorls, shallower suture and flattened whorls, and shell surface with dense and fine radial striae.

Syntypes NHMUK 1859.8.1.10 (3 shells; Fig. 12G) from Siam.

Phra (Buddha) Cave, Tanintharyi Region, Myanmar (11°14'01.5"N, 99°10'42.8"E): CUMZ 13075 (1 shell). The limestone karsts located close to Lampane Village, Tanintharyi Region, Myanmar (11°40'18.1"N, 99°13'30.1"E): CUMZ 13076 (2 shells; Fig. 12H).

Shell slender, conical, translucent, whitish colour, and with 8–8½ whorls. Apex rounded; protoconch ~ 2 whorls, turreted and with nearly smooth to fine radial striations; subsequent whorls with dense and fine radial striations. Spire high, turreted, gradually, and cylindrically tapering; whorls flatly convex, last three whorls nearly equal; suture deep. Aperture narrowly ovate and elongate; peristome thin; columella truncated and concave; columellar margin slightly expanded. Umbilicus narrowly opened to closed.

This species was first described in Thailand, then subsequently recorded in Laos and Malaysia (Naggs 1994; Maassen 2001; Inkhavilay et al. 2019), and is here reported from the Tanintharyi Region, Myanmar.

Paropeas turricula can be differentiated from P. tchehelense by its slender shell, cylindrically turreted spire, and finer striations, while P. tchehelense has a broader and larger shell, a more rounded and broader spire, and stronger radial striations. This species can also be separated from P. terebralis from Shan State by having finer sculpture, flatly convex whorls, shallower suture, and embryonic whorls that are more turreted with nearly smooth to weaker striations, whereas P. terebralis displays a more elongated shell, thicker sculptures, more convex whorls, deeper suture, and embryonic whorls more rounded with stronger striations. Paropeas swettenhami has a larger shell, stronger striations, and wider and more deeply concave columella.

Syntypes UMZC I.103115.A (5 shells; Fig. 12I, after Preece et al. 2022: fig. 56e) ex. R. McAndrew collection from Andaman Island.

NHMUK 1885.2.18.13–18 ex E.S. Berkeley collection Viper Id. Andamans: (6 shells; Fig. 12J). Aik Kham Cave, Taunggyi Township, Taunggyi District, Shan State, Myanmar (20°49'07.0"N, 97°13'42.0"E): CUMZ 13077 (3 shells; Fig. 12K). Ywangan Village, near Lin Way Monastery, Kalaw Township, Taunggyi District, Shan State, Myanmar (21°13'43.3"N, 96°33'19.2"E): CUMZ 13078 (2 shells; Fig. 12L).

Shell slender, conical, translucent, whitish to pale yellowish colour, and with 8–8½ whorls. Apex rounded; protoconch ~ 2 whorls, rounded and with fine radial striations on entire whorls. Spire high, gradually tapering, and turreted; whorls flatly convex and last three whorls nearly equal; suture narrow and deep. Aperture narrowly ovate and elongate; peristome thin; columella straight or slightly concave; columellar margin simple to slightly expanded. Umbilicus narrowly opened to closed.

This species was originally described from the Andaman Islands, India, and was later recorded in Shan State, Myanmar and Thailand (Gude 1914; Panha 1998).

In Myanmar, Paropeas terebralis and P. walkeri are both recorded from Shan State. However, P. walkeri possesses broader, fewer, and more convex whorls, a straight columella with a slightly reflected columellar margin, weaker radial striations, shallow suture, and embryonic whorls rounded. By contrast, P. terebralis has slimmer, higher, and flatter whorls, more concave columella, strong radial striations, deeper suture, and more pointed embryonic whorls. Additionally, P. walkeri also differs from P. turricula by its more convex whorls, straight columella, slightly reflected columellar margin, finer and crowded radial striations, deeper suture, and embryonic whorls rounded with stronger radial striations. Furthermore, P. walkeri can be differentiated from P. swettenhami by its slenderer shell, convex and closely grow whorls, deeper suture, more rounded protoconch whorls, distinctly turreted spire, and straight columella. Prosopeas swettenhami displays a broader shell, flatter whorls, shallow suture, convex protoconch whorls, less turreted spire, and more concave columella.

Among the specimens examined from Shan State, we observed shell variations, such as the columellar margin being either expanded or not expanded and the columella being straight or slightly concave. In addition, the specimen identified as P. walkeri from the Andaman Islands (Fig. 12J) exhibits a broader shell and a more expanded columellar margin compared to the syntype specimen (Fig. 12I).

Achatina tenuispira Benson, 1836 by original designation.

Shell slender and conical; spire high, turreted, and regularly attenuated; embryonic whorls smooth or with striations and subsequent whorls have thick or fine and equally or irregularly spaced radial ribs. Aperture oblique, narrow to broad, and ovate shape; columella concave and truncated; columellar margin not expanded. Penis large, thick, and moderately long; epiphallus relatively long; flagellum present with tubular shape; epiphallic caecum present; vagina enlarged, short ~ 1/2 of penis length.

Originally, Godwin-Austen (1920) proposed Rishetia as a subgenus of Glessula, which Schileyko (1999) raised to the generic level, followed by Raheem et al. (2014), Budha et al. (2017), and Preece et al. (2022). Rishetia can be distinguished from Glessula by having a slender elongate-conical shell with a tubular-shaped flagellum and epiphallic caecum present, while Glessula processes an ovate-conical shell with a comb-like flagellum and epiphallic caecum absent (Tables 2, 3).

Rishetia can generally be differentiated from Bacillum by having a narrowly attenuated shell, convex and smaller apex, straight columella, and weak striations; Bacillum has a cylindrical shell, large and rounded apex, more concave columella, and stronger radial striations (Table 2). More information on the genitalia as well as a molecular phylogeny based on multiple species will clarify the systematic relationship of these two genera.

This genus has been documented in India, Sri Lanka, Bangladesh, and Nepal, with its presence in Southeast Asia limited to Myanmar (Godwin-Austen 1920; Schileyko 1999; Raheem et al. 2014; Budha et al. 2015, 2017). Currently, 23 species are recognised; among these, eleven species and subspecies have been documented from Myanmar (Godwin-Austen 1920; MolluscaBase 2023).

Syntypes NHMUK 1906.1.1.2207 [re-registered in error as 1985138] (6 shells; Fig. 13A–C). ex. W.T. Blanford ex. Godwin-Austen collection from Akouktoung, Pegu.

Figure 13. 

A–C Rishetia akouktoungensis, syntypes NHMUK 1906.1.1.2207 from Akouktoung, Pegu D Rishetia baculina, syntypes NHMUK 1909.3.15.9 from Kursiong, Darjiling E, F Rishetia basseinensis, syntypes NHMUK 1909.3.15.19 from Bassein G–I Rishetia burrailensis maxwelli G holotype NHMUK 1903.7.1.1717/1 from Naga Hills, East of Kohima H specimen NHMUK 1988147 from Somra Tracts, Somra Khulen Post, west of Kyengdwen River, Burma and I paratypes NHMUK 1903.7.1.1717/2–4 from Naga Hills, East of Kohima.

Shell elongate, turreted, and regularly attenuated; apex rounded; subsequent whorls nearly smooth and with coarse radial ridges near suture. Suture impressed and whorls flattened convex. Aperture broadly ovate; columella strong, concave, and truncated.

The species is currently known from its type locality, in which the modern name is Akauk Taung [hill, ~ 18°30'33.7"N, 95°06'48.5"E], south of Htone Bo (or Tonbo) Village, Padaung Township, Pyay District, Bago Region].

The original description did not include an illustration, and only one set of measurements was given. Godwin-Austen’s description was based on one lot of specimens which clearly stated ‘Type No. 2207.06.1.1 B.M.’ (NHMUK 1906.1.1.2207). There are six specimens from the NHMUK type collection with the original label stating ‘Type’. The specimen that has a similar shell measurements as given in the original description and with pink wool inside the shell is figured herein (Fig. 13A). Other shells from the same syntype lot are also illustrated (Fig. 13B, C).

Syntypes NHMUK 1909.3.15.9 [re-registered in error as 19850144] (3 shells; Fig. 13D) ex. Godwin-Austen ex. Blanford collection from Kursiong, Darjiling.

Shell slender, elongate turreted and rapidly attenuated; apex rounded; subsequent whorls with fine and equally spaced radial ribs throughout. Suture impressed and whorls slightly convex. Aperture obliquely ovate; columella strong, concave, and truncated.

This species was originally discovered in India and later reported from the Magway Region, Myanmar (Godwin-Austen 1920).

Godwin-Austen (1920: 15) stated that specimens identified to this species in the Beddome collection were collected from ‘Thyet Myo’ [Thayet District, Magway Region]. However, the Myanmar specimens show noticeable differences from the type specimens in having a more attenuated apex, and larger and broader aperture.

Syntypes NHMUK 1909.3.15.19 [re-registered in error as 1985139] (3 shells; Fig. 13E, F) ex. Blanford ex. Godwin-Austen collection from Bassein, Pegu.

Shell slender, elongate turreted and regularly attenuated; apex rounded and blunt; subsequent whorls with fine and equally spaced radial ribs, which more prominent near suture. Suture impressed and whorls flattened convex. Aperture ovate; columella strong, concave, and truncated.

Rishetia basseinensis appears to be restricted within Myanmar and is known only from the type locality. Based on the current administrative boundary, ‘Bassien (or Pathein), Pegus’ is in the Pathein Township, Pathein District, Ayeyarwady Region, rather than Pegu [Bago Region].

Godwin-Austen (1920: 53) stated that when examining the type series of ‘Glessula pertenuis var. major’ ex. Blanford collection, he found it very different from the nominotypical taxon, and described this specimen lot under a different name, ‘Glessula basseinensis’. In the original description, Godwin-Austen (1920: 54) provided two collection localities, namely ‘Bassein, Pegu’ and ‘Pyema Khyoung, Bassein’ and comparing three and six specimens, respectively. The description clearly states a catalogue number ‘Type No. 19.9.3.15 B.M.’ and includes an illustration of specimens from ‘Bassein, Pegu’. The NHMUK collection contains this specimen lot NHMUK 1909.3.15.19 consisting of three shells with an original label in Godwin-Austen’s handwriting stating ‘Type’ from the H.F. Blanford collection. The specimen with a similar shell measurement given in the original description and with pink wool inside the shell is figured herein (Fig. 13E). Additionally, one further shell from the same syntype lot is also illustrated (Fig. 13F).

The specimen lot NHMUK 1909.1.1.2208 is excluded from the type series of this species (see also under the Rishetia pertenuis major).

Holotype NHMUK 1903.7.1.1717/1 (Fig. 13G) ex. Godwin-Austen collection from Naga Hills, East of Kohima. Paratypes NHMUK 1903.7.1.1717/2–4 (3 shells; Fig. 13I) ex. Godwin-Austen collection from the location same as the holotype.

NHMUK 1903.7.1.3742 (7 shells + 1 broken shell; Fig. 14A, B) collected by F. Ede ex. Godwin-Austen collection from Somra Tracts, Somra Khulen Post, Burma (labelled as ‘var. somraensis’). NHMUK 1903.7.1.3744 (2 shells; Fig. 14C) collected by F. Ede ex. Godwin-Austen collection from Somra Tracts, Somra Khulen Post, Burma (labelled as ‘var. somraensis’). NHMUK 1988147 (4 shells; Fig. 13H) collected by L.R. Mawson from Somra Tracts, Somra Khulen Post, west of Kyengdwen River, Burma.

Figure 14. 

A–C Rishetia burrailensis maxwelli A, B specimen NHMUK 1903.7.1.3742 from Somra Tracts, Somra Khulen Post, Burma and C specimen NHMUK 1903.7.1.3744 from Somra Tracts, Somra Khulen Post, Burma D Rishetia hastula, neotype NHMUK 1906.1.1.880 from Darjiling E, F Rishetia kentungensis, syntypes NHMUK 1903.7.1.3650 from Mong Sing, Siam Boundary G Rishetia limborgi, holotype NHMUK 1903.7.1.3200 from Tenasserim H, I Rishetia nathiana, syntypes NHMUK 1906.1.1.2206 from Bassein District.

Shell elongate, turreted, and regularly attenuated; apex rounded and blunt; subsequent whorls nearly smooth with fine irregularly spaced radial ridges throughout, and coarser ridges appearing near suture. Suture impressed and whorls flattened. Aperture ovate; columella concave and truncated.

This subspecies was originally described from the Naga Hills. The locality reported in Myanmar is Somra Town (~ 25°21'43.6"N, 94°41'14.4"E), a mountainous area in Leshi or Layshi Township, Sagaing Region in northwestern Myanmar. It is neighbouring Nagaland to the west and Kachin State to the east and along the Chindwin River.

The name maxwelli was stated twice in the same publication, on pages 45 and 61. The first mention is ‘Glessula (Rishetia) burrailensis, var. maxwelli’; when proposing this name, Godwin-Austen (1920: 45) recognised two specimen lots from Naga Hills… (collected by Col. H. St. P. Maxwell) and from Somra… Upper Burma (collected by F. Ede). Although the species description is brief, Godwin-Austen provides the catalogue number ‘No. 1717 B.M.’, two sets of shell dimensions, and illustrations of two shells from Naga Hill. We have examined this specimen lot, NHMUK 1903.7.1.1717, from Naga Hills, which consists of four shells. In the original description, Godwin-Austen (1920: 46) further states, ‘Size: Fig. 5. Type’ and in the figure caption as ‘Fig. 5. (1^st Type) from Naga Hills’ and ‘Fig. 6. (2^nd Type) from Naga Hills’. It seemed that Godwin-Austen intended to designate the specimen figured in plate 160, fig. 5, as the unique name-bearing type, which we consider as the holotype. The other three specimens from the same lot are therefore paratypes.

The second mention is ‘Glessula burrailensis, var. maxwelli’, for which Godwin-Austen (1920: 61) provided a very detailed description together with specimen lot number ‘No. 3742 B.M.’, two sets of shell measurements, from ‘Somra Tracts, Somra Khulen Post, Upper Burma, but without illustration. The NHMUK collections contain specimen lot NHMUK 1903.7.1.3742, consisting of eight specimens with the original label stating ‘var. somraensis, GA.’. This manuscript name has never properly been published and made available (ICZN 1999: Art. 10), the specimen lot NHMUK 1903.7.1.3742, with its original label stating ‘var. somraensis’ is considered as the syntype. Therefore, this second combination becomes an available name (ICZN 1999: Arts 11, 12), and it is considered a junior (primary) homonym (ICZN 1999: Arts 24.2.1, 24.2.2, 53.3, 57.2). Additionally, syntypes also include, NHMUK 1988147 (4 shells), from Somra, Khulen Post, West of Kyendwin River, Upper Burmah, as Godwin-Austen (1920: 61) recognised in the original description.

After examining the type specimens carefully, we found no differences in the diagnostic characters between the senior homonym (NHMUK 1903.7.1.1717/1 and NHMUK 1903.7.1.1717/2–4) and junior homonym (NHMUK 1903.7.1.3742, NHMUK 1903.7.1.3744 and NHMUK 1988147) specimens, especially shell shape, shell sculpture, and protoconch sculpture. The only detected difference is the brownish or yellowish brown periostracum, which we consider as intraspecific variation. Therefore, it seems unnecessary to propose a new replacement name for this junior homonym.

Neotype NHMUK 1906.1.1.880 (designated in Preece et al. 2022: 127, fig. 55a) (Fig. 14D) ex. Blanford collection from Darjiling.

Shell elongate, turreted, and regularly attenuated; apex rounded and blunt; subsequent whorls coarse with fine equally spaced radial ridges throughout. Suture somewhat impressed and whorls convex. Aperture broadly ovate; columella strong, concave, and truncated.

The species was originally described from India and later recorded from Nepal (Ramakrishna et al. 2010; Budha et al. 2015; Kalita 2022). In Myanmar, it was reported from Kumah Hill and Maii [Ma-ei Town ~ 19°20'36.5"N, 94°08'21.9"E], which are in the Thandwe District, Rakhine State in the westernmost part of Myanmar (Theobald and Stoliczka 1872; Gude 1914; Godwin-Austen 1920).

To clarify the taxonomic status of this species, Preece et al. (2022) have designated a neotype based on the specimen figured in Hanley and Theobald (1870, pl. 18, fig. 4). However, the image used to represent the neotype in Preece et al. (2022: fig. 55a) is an erroneous repetition of ‘Achatina leptospira Benson, 1865’ (see Preece et al. 2022: fig. 51f). Therefore, the correct image of the neotype NHMUK 1906.1.1.880 is illustrated herein.

Theobald and Stoliczka (1872: 334) noted that the specimens from Arakan tended to differ from the type specimen in having a larger shell size. Nevertheless, Arakan and Sikkim are non-adjacent regions and far apart, which raises doubts about whether they are the same or distinct species.

Syntypes NHMUK 1903.7.1.3650 [re-registered in error as 1986002] (3 shells + 1 juvenile; Fig. 14E, F) collected by Woodthorpe ex. Godwin-Austen collection from Mong Sing, Siam Boundary.

NHMUK 1903.7.1.3748 (4 shells) collected by Woodthorpe ex. Godwin-Austen collection from the Mekong River.

Shell elongate, turreted, and regularly attenuated; apex rounded, blunt and with very large embryonic shell; subsequent whorls nearly smooth throughout, and prominent irregularly spaced radial ridges near suture. Suture impressed and whorls slightly flattened. Aperture broadly ovate; columella strong, concave, and truncated.

This species was initially found in Laos; however, as noted by Godwin-Austen (1920), its presence in the Mekong River region is assumed to likely extend to the East Shan State.

The original description gave the measurements for only one shell and did not include an illustration. Godwin-Austen (1920) clearly states the collection locality and the catalogue number ‘Type No. 3650 B.M.’. The NHMUK collections contain a lot of four specimens from the Godwin-Austen ex. Woodthorpe collection with an original label stating ‘Type’ and giving the collection locality as ‘Mong Sing, Siam Boundary’. The two specimens match well with the original description, and shell dimensions are illustrated herein. Another specimen, lot ‘No. 3748 B.M.’ from the ‘Mekong River’, is excluded from the type series of this nominal species.

Originally, the type locality was said to be from ‘Mong Sing, Siam Boundary’; currently, this locality refers to Muang Sing District, Luang Namtha Province, Laos. The specimen NHMUK 1903.7.1.3748, collected from the ‘Mekong River’ by Colonel R. G. Woodthorpe, has a vague locality that could possibly encompass the East Shan State (formerly Keng Tung State) and the Bokeo and Luang Namtha provinces in Laos.

Holotype NHMUK 1903.7.1.3200 [re-registered in error as 1985219] (Fig. 14G) collected by Limborg ex. Godwin-Austen collection from Tenasserim.

Shell elongate, turreted and regularly attenuated; apex rounded; subsequent whorls with fine and equally spaced radial ridges throughout. Suture impressed and whorls flattened. Aperture broadly ovate; columella strong, concave, and truncated.

This species is known only from the type locality and is likely endemic to that region.

Godwin-Austen (1920) clearly states that this taxon was described based on only a single specimen collected by O. Limborg. The original description included only a single set of shell measurements but was without illustration. The NHMUK collections contain the type specimen lot, NHMUK 1903.7.1.3200 ex. Godwin-Austen ex. O. Limborg consisting of a single shell with an original label stating ‘Type’. Therefore, we considered this shell as the holotype fixed by monotypy.

Syntypes NHMUK 1906.1.1.2206 [re-registered in error as 1986018] (5 shells; Fig. 14H, I) ex. Blanford collection from Bassein District.

Shell elongate turreted and regularly attenuated; apex rounded and blunt; subsequent whorls with very fine equally spaced radial ridges, which coarser near suture. Suture impressed and whorls flattened convex. Aperture broadly ovate; columella concave and truncated.

Rishetia nathiana is known only from the type locality and is likely endemic to that region.

Godwin-Austen clearly stated that the original description was based on a specimen lot, ex. W.T. Blanford collection with the catalogue number ‘Type No. 2206.06.1.1 B.M.’. The NHMUK collections contain a lot of five specimens from the Godwin-Austen ex. Blanford collection with original label ‘Type’ and ‘ex. duplicate collection’. The specimen matches well with the given shell measurements, and the original description is illustrated herein for the first time.

Possible syntypes NHMUK 1906.2.2.239 (7 shells; Fig. 15A, B) ex. Blanford collection from Henzada, Pegu and Tongoop, Arakan.

NHMUK 1888.12.4.1229–31 (3 shells; Fig. 15D, E) from Pegu. NHMUK 20230921 (5 shells) from Tongoop, Arakan (Fig. 15C).

Figure 15. 

A–E Rishetia pertenuis A, B possible syntypes NHMUK 1906.2.2.239 from Henzada, Pegu and Tongoop, Arakan C specimen NHMUK from Tongoop, Arakan and D, E specimen NHMUK 1888.12.4.1229–31 from Pegu F, G Rishetia pertenuis major, possible syntypes NHMUK 1906.1.1.2208 from Pyema Khyoung, Bassein H Rishetia tenuispira, specimen NHMUK 1903.7.1.3332 from Garo Hills.

Shell slender, elongate turreted, and rapidly attenuated near apical whorls; apex rounded; subsequent whorls nearly smooth, fine growth lines, and with equally spaced ridges near suture. Suture impressed and whorls slightly convex. Aperture ovate; columella concave and truncated.

This species was reported from several places in Myanmar: Henzada [Hinthada City, Ayeyarwady Region], Thayet Myo [Thayet City, Thayet District, Magway Region], Pegu [Bago Region], and Tongoop, Arakan [Taungup Township, Thandwe District, Rakhine State] (Nevill 1878; Gude 1914). It was also reported from Meghalaya State, India (Ramakrishna et al. 2010).

The original description does not clearly state how many specimens were available to the author, although only one set of measurements was given. The NHMUK collection contains a lot of seven specimens from the Blanford collection with this species name. However, this is a mixed specimen lot of the same species as it consists of two collection localities, ‘Henzada, Pegu’ and ‘Tongoop, Arakan’, where only the latter was mentioned in the original description as the type locality. Therefore, this specimen lot NHMUK 1906.2.2.239 is considered as possible syntypes, from which two specimens are illustrated herein.

Possible syntypes NHMUK 1906.1.1.2208 (6 shells; Fig. 15F, G) ex. Blanford collection from Pyema Khyoung, Bassein; label state ‘Glessula basseinensis G-A.’

Shell elongate, turreted and regularly attenuated; apex rounded and blunt; subsequent whorls with fine equally spaced radial ridges throughout, which coarser near suture. Suture impressed and whorls slightly flattened. Aperture broadly ovate; columella strong concave and truncated.

This subspecies was known solely from the type locality.

When describing ‘Achatina pertenuis’, Blanford (1865) recognised the larger shells as a distinct variety and gave them the name ‘var. major’. This taxon name was made available, although without description, because the two sets of shell dimensions and materials from ‘Pyema Khyoung, Bassein district, Pegu’ confer the indication (ICZN 1999: Arts 11.9 and 12).

The type series of the taxa could not be traced. Only one specimen lot from the Godwin-Austen collection belongs to W.T. Blanford’s original type series., i.e., NHMUK 1906.1.1.2208, with the original label in Godwin-Austen’s handwriting marked ‘ex. duplicate collection Blf., intermediate between A. tenuispira and A. pertenuis’, with a species name ‘Glessula basseinensis G-A.’, and collection locality ‘Pyema Khyoung, Bassein’. Therefore, this specimen lot is here considered as possible syntype material, and the two shells closest to the shell measurements given in the original description are illustrated herein.

The modern name of ‘Pyema Khyoung, Bassein District, Pegu’ is the PyayMa Khaung or Pyinma Khuang (~ 18°38'51.7"N, 95°45'46.9"E), Pathein Township, Pathein District, Ayeyarwady Region, Myanmar.

The type specimen could not be located in the UMZC collection (Raheem et al. 2014; Preece et al. 2022). However, Budha et al. (2017: fig. 14a) figured a possible syntype of this species based on specimens ex. Benson collection from ‘Teria Ghat’, this specimen lot was not considered to form part of the type series by Preece et al. (2022).

NHMUK 1946.10.16.1–7 (7 shells) ex. R. McAndrew collection from Pegu. NHMUK 1903.7.1.3332 (1 shell; Fig. 15H) labelled as ‘var.’ ex. Godwin-Austen collection from Garo Hills. UMZC I.102045 from Teria Ghat (Budha et al. (2017: fig. 14a) recognised this specimen as a possible syntype).

Shell elongate, turreted, and regularly attenuated; apex rounded; subsequent whorls with fine equally spaced radial ridges throughout and more prominent near suture. Suture impressed and whorls slightly flattened. Aperture elongate ovate; columella concave and truncated.

This species is broadly distributed in Bangladesh, India, and Nepal (Budha et al. 2015; Preece et al. 2022). It was also reported from several localities in the southwest and eastern Myanmar: Ayeyarwady, Bago, and Tanintharyi regions (Benson 1860; Blanford 1865; Beddome 1906).

Benson (1860: 464) reported that Theobald found a variety of ‘Achatina tenuispira’ on the banks of Irrawaddy [Ayeyarwady River] and from Phie Than [probably in Tanintharyi Region]. Blanford (1865) recorded the presence of a small-sized species in Akoutoung [Akauk Taung, Ayeyarwady Region] and further south, while Beddome (1906) noted its occurrence in Pegu [Bago Region].

Achatina erecta Benson, 1842, by original designation.

Shell slender, cylindrically shaped; spire high, mostly turreted, and gradually attenuated; embryonic whorls smooth, and subsequent whorls with nearly smooth to strong radial ribs. Aperture vertical, narrow, and oblong; columella concave or straight and with spiral fold below; columellar margin with or without expansion near umbilicus. Umbilicus narrowly opened or closed.

Tortaxis can be distinguished from other subulinid taxa from Myanmar, namely Allopeas, Opeas, and Bacillum, by having a slender, cylindrical, and turreted spire, flatter whorls, smooth embryonic whorls, a large and rounded apex, and a distinct spiral fold on the columella (Table 2).

The genus is mainly distributed in Southeast Asia and southern China and comprises 14 extant species (Pilsbry 1906; Schileyko 1999; MolluscaBase 2023) and one Miocene-amber fossil from China (Yu et al. 2023). In Indochina, nine species have been reported from Vietnam, and only one species from Thailand (Panha 1998; Schileyko 2011; Do and Do 2014). In this study, we propose one new species which marks the first record of the genus in Myanmar.

Holotype CUMZ 13079 (height 9.6 mm, width 2.3 mm; Fig. 16G), paratypes CUMZ 13080 (35 shells; Fig. 16H, I), NHMUK 20230919 (2 shells) and SMF (2 shells).

Figure 16. 

A Tortaxis erectus, neotype NHMUK 1991104A from Nanking, China B Tortaxis elongatissimus, syntype MNHN-IM-2000-4705 from Pac-Kha C Tortaxis lubricus, holotype ANSP 66056 from near Haiphong D Tortaxis papillosa, MNHN-IM-2000-33971 from Nam-Nhang E Tortaxis permira, syntype MNHN-IM-2000-4675 from That-Khé, Tonkin F Tortaxis pilsbryi, syntype MNHN-IM-2000-4678 from Bac-Khan et That-Khé G–I Tortaxis cylindrotis sp. nov. G holotype CUMZ 13078 from Taunggyi, Shan State, Myanmar with embryonic whorls and aperture H, I paratypes CUMZ 13079 from the type locality H probably juvenile shell with 7 whorls and I adult shell. Photographs: P Bourguignon & D Brabant (B, D–F).

Parpant area, Taunggyi City, Taunggyi District, Shan State, Myanmar (20°15'3.7"N, 97°14'23.9"E).

The specific name cylindropsis is from the Latin word for cylinder, and the Greek suffix -opis means ‘having the appearance of or like’. It refers to the cylindrical shell shape of this species.

Shell slender cylindrical, suture deeply impressed, spire distinctly turreted, protoconch rounded and smooth, subsequent whorls with fine growth lines and a distinct spiral fold on columellar margin.

Shell (height 9.3–11.7 mm) slender cylindrical in shape,, translucent, whitish to pale yellowish colour, and with 8–9½ whorls. Apex rounded; protoconch ~ 2 whorls, rounded and with smooth surface; subsequent whorls with fine growth lines more distinct on last whorl. Spire high, grows evenly and is largely turreted; whorls flatly convex; last whorls slightly larger than preceding whorls; suture narrow, deep, and weakly crenulated. Aperture vertical, narrowly ovate, and elongate; peristome thin; columella straight; columellar margin slightly expanded with distinct spiral fold. Umbilicus closed.

This species is known only from its type locality.

Comparing this new species with the Vietnamese species, T. comaensis Do, 2014 has a much larger and taller shell (height 56.1–66.4 mm), an attenuated spire, coarser sculptures, a broad aperture, and a thickened peristome, whereas this new species display a much smaller shell (height 9.3–11.7 mm), grows evenly and has a cylindrical spire, smooth shell surface, narrow aperture, and thin peristome (Do and Do 2014). Tortaxis erectus (Benson, 1842) has a less turreted shell, wide and flatly convex whorls, and a shallow suture (Fig. 16A), while T. cylindropsis sp. nov. has a distinctly turreted, slender shell with narrow and convex whorls, and a deep suture. Tortaxis elongatissimus Bavay & Dautzenberg, 1909 possesses a more elongated shell with stronger radial ribs and a more attenuated spire (Fig. 16B) than this new species. Tortaxis lubricus Pilsbry, 1906 has a broad last whorl, attenuated spire, wider aperture, and shallow suture (Fig. 16C); in contrast, the shell of T. cylindropsis sp. nov. presents narrowly and even whorls, cylindrical, slender, and turreted spire, narrow aperture, and deep suture. Tortaxis papillosa Dautzenberg & Fischer, 1908 shows a broad shell with an attenuated spire, rounded embryonic whorls, flatter whorls, and a shallow suture (Fig. 16D), whereas T. cylindropsis sp. nov. has a slender shell, with cylindrical spire, convex whorls, and deeper suture. Tortaxis permira (Ancey in Bavay & Dautzenberg, 1904) and T. pilsbryi (Ancey in Bavay & Dautzenberg, 1904) have a wider shell, with a shallower suture, gradually attenuated spire, and an aperture wider than that of T. cylindropsis sp. nov. (Fig. 16E, F).

This genus is reported for the first time in Myanmar, and the present finding expands the distribution range of the genus from China, Vietnam, Laos, and Thailand to include Myanmar.

Pupa insularis Ehrenberg, 1831, subsequent designation by Kobelt (1902: 1022).

Shell pupiform; spire high, broad, cylindrical, and apex pointed; embryonic whorls smooth surface; subsequent whorls with irregularly dense, fine, coarse, or weak radial striations. Aperture oblique, broad, and oblong or rounded; columella straight. Penis long slender tube, and with slightly thickened wall and conical at base; vagina very much larger and muscularly thicker than male organ.

Zootecus can be distinctly distinguished from all subulinid taxa in Myanmar by its pupiform shell, broad spire, straight columella, thickened whitish peristome, and irregular coarse striations (Table 2).

The genus is distributed from the Cabo Verde Islands and the Sahara, extending eastwards to Arabia, Socotra Island, India, and Southeast Asia (Gude 1914; Solem 1966; Schileyko 1999; Neubert 2003). Currently, the genus consists of nine species, and two are known from Myanmar (Gude 1914; MolluscaBase 2023).

Lectotype ZMB 109990 (Fig. 17A, after Raheem et al. 2014: fig. 74c).

NHMUK 1875.12.4.16 (5 shells; Fig. 17B, C) ex. Beddome collection from Burma. SMF 296651/2 (2 shells) ex. Ehrmann collection from Burma.

Figure 17. 

A–C Zootecus insularis A lectotype ZMB 109990 (after Raheem et al. 2014: fig. 74c) and B, C specimen NHMUK 1875.12.4.16 from Burma D–H Zootecus pullus D lectotype NHMUK 1986252/1 and E paralectotype NHMUK 1986252/2 from Banks of the Ganges, South Asia and F–H specimen CUMZ 13081 from Bagan, Mandalay Region, Myanmar.

Shell subcylindrical; spire high and dome-shaped; apex pointed; subsequent whorls with fine and wavy radial striae, which stronger near suture. Aperture semi-ovate; columella short and straight. Umbilicus narrow.

Zootecus insularis has a wide geographic distribution, spanning across the Cape Verde Islands, northeastern Africa, and the Arabian Peninsula. Its range also extends to South Asia, including India, Pakistan, Sri Lanka, and Afghanistan (Pilsbry 1906; Gude 1914; Neubert 2003; Raheem et al. 2014). In Myanmar, it was recorded from ‘Pagan’ [Bagan] in the Mandalay Region (Blanford 1865; Gude 1914).

No new specimens of this species were collected during this survey. However, the specimens collected from Bagan in the Mandalay Region are here identified as Z. pullus rather than Z. insularis (see under Z. pullus for further comparison). The historical museum specimens with brief locality records such as ‘Burma’ (Fig. 17B, C) match well with the respective type specimens of this species (Fig. 17A). As a result, the existence of Z. insularis in Myanmar requires further evidence from newly collected specimens with precise collection locality data, otherwise it must be excluded from the faunal list.

Lectotype NHMUK 1986252/1 (Fig. 17D; designated in Raheem et al. 2014). Paralectotype NHMUK 1986252 (1 shell; Fig. 17E) from Banks of the Ganges, South Asia.

Dhammayazaka Pagoda, Pwasaw Village, Bagan City, Mandalay Region, Myanmar (21°08'40.3"N, 94°52'58.0"E): CUMZ 13081 (70 shells; Fig. 17F–H), CUMZ 13082 (20 specimens in ethanol).

Shell subcylindrical, solid, glossy, pale grey colour, slightly thick, and with 8–9½ whorls. Apex slightly elevated; protoconch ~ 2 whorls, dome-shaped and nearly smooth with fine radial striations; subsequent whorls with dense but fine, wavy, radial striations, stronger near suture. Spire grows evenly; whorls flatly convex; suture wide and shallow. Aperture nearly rounded and wide; columella straight; peristome relatively thickened, expanded, and white. Umbilicus narrowly opened.

Genitalia (n = 5). Atrium undifferentiated. Penis very narrow, slender, almost same length with vagina, and slightly bulging at base. Penial retractor slender, long and attached at junction of penis and vas deferens. Epiphallus very short or indistinct. Vas deferens long, slender tube, and connected between penis/epiphallus to free oviduct (Fig. 18A, B).

Figure 18. 

Genitalia and radula of Zootecus pullus, specimen CUMZ 13082 from Bagan, Mandalay Region, Myanmar A, B reproductive anatomy with inset of the male organ and C radula morphology with inset of central teeth: yellow colour and ‘C’ indicates central teeth row, green colour indicates lateral teeth in the transition to marginal teeth, and numbers indicate tooth order from lateral to marginal end. Abbreviations: fo, free oviduct; gd, gametolytic duct; gs, gametolytic sac; p, penis; pr, penial retractor muscle; so, spermoviduct; v, vagina; vd, vas deferens.

Vagina much larger than penis and cylindrical shape. Gametolytic duct short and slender tube; gametolytic sac distinct and bulbus shape. Free oviduct almost the same diameter as vagina; spermoviduct enlarged.

Radula. Each row contains ~ 43+ teeth with half-row formula: central-lateral-marginal teeth (1–(11–13)–(6–7+)). Central tooth relatively small, tricuspid with pointed central cusp, and small, rounded, lateral cusps. Lateral teeth bicuspid: endocone large rhomboid in shape and with pointed to dull tip; ectocone small, pointed tip and located at middle of tooth height. Marginal teeth asymmetrically tricuspid starting approximately at tooth number 11–13: mesocone large, triangular, and curved to blunt tip; endocone small and located near tip of mesocone; ectocone triangular, pointed tip and located near tooth base. Outermost teeth small and polycuspid (Fig. 18C).

Apart from Myanmar, this species is likely to occur in India and Bangladesh (Raheem et al. 2014).

In Myanmar, the previous records of Z. pullus were from ‘Ava’ [Innwa in Mandalay Region]. Our newly collected specimens from Bagan (~ 150 km southwest of Innwa) are identified as this species, but they present some differences such as having a long and narrower shell and a blunt apex. Zootecus pullus has a penis nearly equal in length to the vagina, and the penis is slightly enlarged with a conical shape at base near the atrium (Fig. 18A, B), while Z. insularis possesses a penis shorter than the vagina, and the evenly slender penis (see Schileyko 1999: fig. 678 from a near type locality in the Red Sea). Further investigation is required to determine whether these two Myanmar species are distinct or simply demonstrate variation in shell morphology.