Cyclostoma pollex Gould, 1856: 14; by monotypy (see ICZN, 1999, Art. 68.3). The type species ‘Cyclostoma pollex Gould, 1856 [October]’ is currently recognized as a junior subjective synonym of Megalomastoma gravidum Benson, 1856 [March].

When describing his new species as Cyclostoma pollex, Gould (1856) simultaneously proposed the new generic name Pollicaria for this new nominal species. Gould also doubtfully included Cyclostoma myersii Haines, 1855 and Cyclostoma chrysalis Pfeiffer, 1852 in the Pollicaria Gould, 1856. Benson (1859) published a new generic name Hybocystis containing a single species from Burma Megalomastoma gravidum Benson, 1856. Although Benson (1860) noted that Hybocystis was a junior subjective synonym of Pollicaria Gould, 1856, the name Pollicaria was widely overlooked prior to Kobelt’s (1902) review of cyclophoroideans and both Wenz (1938) and Pain (1974) continued to mistakenly cite Megalomastoma gravidum Benson, 1856 as the type species. With only the doubtful inclusion of Cyclostoma myersii Haines, 1855 and Cyclostoma chrysalis Pfeiffer, 1852 in the original description of Pollicaria, the type species of Pollicaria was unequivocally fixed in the original publication by monotypy.

Shell pupoid, small to large (shell height 35–50 mm), thickened and solid. Shell smooth or malleated sculpture from almost white to pale yellow, reddish brown and nearly black; periostracum generally thick. Whorls 5–7, last whorl expanded, body whorl distorted when adult; sutures weakly impressed. Aperture rounded, shallow to absent posterior angled groove; peristome continuous and thickened; lip duplicated and reflexed; umbilicus narrow. Operculum multi-lamellar calcareous plate. Radula taenioglossate with seven teeth in each transverse row.

Five shells in the type series of W.H. Benson, the specimen with similar shape, size and colour to the original description is designated here as the lectotype of Megalomastoma gravidum Benson, 1856 UMZC I.102935.A (height 32 mm, width 18 mm; Fig. 4A) and paralectotypes UMZC I.102935.B-E (4 shells, Fig. 4B); syntype of Otopoma blennus Benson, 1856 UMZC I.102930.A-B (2 shells, Fig. 4C).

Burma: NHMUK 79.9.1.5-6 (2 shells), Theobald colln. Acc. no. 1592 (2 shells), B.R. Lucus colln. Acc. no. 2351 (2 shells), Trechmann colln. Acc. no. 2176 (2 shells), 2 lots of E.R. Sykes collns. Acc. no. 1825 (1 shell and 2 shells); ZMA: R.v. Lennep colln. Acc. no. 1876 (1 shell); ZMB: Paetel colln. (1 shell), 2 lots of Dunker collns. (1 shell, 2 shells), Nevill colln. ZMB 20723 (2 shells). Farm Cave, Moulmein: NHMUK 88.124.863.4-5 (3 shells, Fig. 4D, E). Moulmein, Burma: NHMUK 71.9.23.193 (1 shell), 24.06.4.4 (2 shells), 1954.6.2.1231-1 (2 shells), H. Cuming colln. (4 shells), 2 lots of H.F./W.T. Blanford collns. Acc. no. 1944 (5 shells, 2 shells), T. Oldham colln. Acc. no. 1733 (2 shells); ZMA: Schepman colln. (1 shell). Unknown locality: NHMUK V.W. MacAndrew coll. (4 shells), H.E.J. Biggs colln. Acc. no. 2258 (2 shells), H. Cuming colln. (1 shell).

Shell. Shell small for Pollicaria, pupoid, pale orange, yellow to white. Periostracum thin and transparent; shell surface smooth. Whorls 5–6; sutures moderately impressed; apex slightly inclined to right; spire short. Last whorl large about two-thirds of shell height, distorted and flattened in front. Aperture rounded with a shallow posterior angled groove. Peristome continuous, with distinct parietal declining shoulder internally. Lip thickened, little expanded, and margin moderately duplicated; umbilicus narrow. Operculum thick, calcareous, multispiral.

Accepted records are confined to Burma: Moulmein, Damontha, Tavoy and Tenasserim (Benson 1856, 1859, Stoliczka 1871, Crosse 1885, Kobelt 1902, Gude 1921, Pain 1974). Records from Northern Vietnam of Pollicaria crossei and Pollicaria rochebruni are considered to be distinct species.

Otopoma blennus Benson, 1856 and Cyclostoma pollex Gould, 1856 have long been considered as junior synonyms of Pollicaria gravida and this classification has been followed by a number of authors (Hanley and Theobald 1870, Sowerby 1878, Crosse 1885, Kobelt 1902, Pain 1974). Subsequently, Pollicaria crossei and Pollicaria rochebruni from Vietnam were also placed into synonymy with this species (see Pain 1974). However, examination of the type specimens of these three species (Figs 4A, B; 5D, F) demonstrated that Pollicaria gravida could be distinguished from Pollicaria crossei and Pollicaria rochebruni by having a whitish to yellowish shell colour with swollen whorls, impressed sutures and with the last whorl flattened ventrally (Table 1). Furthermore, Pollicaria gravida is mainly restricted to the western edge of the Pollicaria distribution in Tavoy and Tenasserim of Burma, and does not overlap with the two Vietnamese species in the east (Pain 1974). Unfortunately, none of the live specimens of Pollicaria gravida were examined cytogenetically for additional discrimination of these three species.

Siam: NHMUK 20090242 (Fig. 4F). Pahom, Vang Vieng, Laos: CUMZ 1531, 1572 (Fig. 4G), 1591; ZMMSU 0009.

Shell: Shell large, reddish brown to light orange. Periostracum thin, corneous; shell surface usually with fine malleations on upper half of last whorl. Aperture almost circular with a shallow posterior angled groove. Peristome yellow, parietal declining shoulder absent. Lip thickened, broadly expanded, reflexed, with concentric margin.

Radula: Radular teeth arranged in v-shaped rows, each transverse row with 7 teeth (2-1-1-1-2). Central tooth with well developed central cusp and one smaller lateral cusp on each side; central cusp large, elongate with pointed tip. Lateral teeth with 2 cusps, outer cusp largest and elongate shape with pointed tip, and with relatively small pointed tip of inner lateral cusps. Inner and outer marginal teeth with 2 cusps; central cusp large, flanked by small inner lateral cusps.

The type locality of this species was given as the broad location of “Siam” (see Haines 1855). Subsequently, Pollicaria mouhoti was synonymised with Pollicaria myersii (von Martens 1867, Pain 1974) thus expanding the distribution of Pollicaria myersii beyond its historical range. However, in this study the distribution of the species is restricted to limestone areas of Vientiane to Luang Prabang, Laos, and probably the northern part of Thailand.

The syntype AMNH 43629 could not be traced (Siddal and Watson, personal communication). Due to the proximity of the geographic distributions and similarity in shell morphology of the two species, Pollicaria mouhoti have long been considered a junior synonym of Pollicaria myersii (see Pain 1974). However, Pollicaria myersii can be distinguished from Pollicaria mouhoti by an elongated purple to pale orange shell with thin periostracum, rounded aperture and very fine wrinkles on the dorsal part of the last whorl (Table 1, Fig. 4F, K). Pollicaria myersii differs from Pollicaria gravida, Pollicaria rochebruni and Pollicaria crossei by having a larger shell, no apertural groove and noticeable wrinkles on last whorl (Tables 1, 2).

Shell small to large, pupoid, solid; monochrome purple to black, sometimes with yellowish to bright orange spire. Periostracum thin; shell surface with distinct malleations on upper half of last whorl. Whorls 5-6; sutures moderately impressed; apex obtuse. Last whorl large about two-thirds of shell height, distorted and flattened in front. Aperture almost circular, shallow posterior angled groove present. Peristome and inside aperture orange to red; parietal declining shoulder absent. Lip thickened, expanded, reflexed, margin slightly duplicated; umbilicus narrow. Operculum calcareous concentric.

The type locality of Pollicaria mouhoti was given as Laos Mountain, Cambodia. However, subsequent records of this species were from Thailand, Laos and Cambodia (Pfeiffer 1862, Crosse 1885, Kobelt 1902, Solem 1966).

von Martens (1867) and Pain (1974) synonymised this species with Pollicaria myersii and stated that all Pollicaria specimens collected from Thailand should be regarded as this species. However, examination of the type specimens of Pollicaria mouhoti (Fig. 4H) showed that it was clearly distinct from Pollicaria myersii in shell shape, sculpture and colour pattern. The major distinguishing shell characters of Pollicaria mouhoti are the smaller shell size, purplish shell colour, bright orange spire, expanded bright orange to red apertural lip and bold wrinkles on the dorsal side of last whorl (Tables 1, 2). In addition, the chromosome analysis shows a clear difference in karyotype patterns between these two species (Kongim et al. 2009, 2010). Hence, Pollicaria mouhoti is removed from the synonymy of Pollicaria myersii and reinstated as a distinct species.

Three syntype shells in H. Cuming collection, the figures and labels with type specimen are designated here as the lectotype of Hybocystis mouhoti Pfeiffer, 1862 NHMUK 20130071/1 (height 34.2 mm, width 18.1 mm; Fig. 4H) and paralectotype NHMUK 20130071/2-3 (2 shells). Cambodia: ZMA Wright colln. (2 shells), R.v. Lennep colln. (1 shell). Laos Mountain: ZMB Paetel colln. (1 shell). Phu Kradung, Loei: CUMZ 1586. Namnao National Park, Phetchabun: CUMZ 1574, 1538; ZMMSU 0002. Tam Yai Namnao, Phetchabun: CUMZ 1559. Phu Phaman, Khon Kaen: ZMMSU 0012. Phu Kiew Wildlife Sanctuary, Nongbuadang, Chaiyaphum: CUMZ 1528, 1529, 1551, 1571, 1576, 1582, 1585; ZMMSU 0003, 0020-4, 0027, 0029. Phu Phachit, Chaiyaphum: ZMMSU 0013. Tam Tao, Nernmaprang, Phitsanulok: CUMZ 1558. Tam Wungdang, Nernmaprang, Phitsanulok: CUMZ 1533 (Fig. 4I), 1537, 1544, 1554, 1575. Wat Pa Mamuang, Nernmaprang, Phitsanulok: CUMZ 1541; ZMMSU 0015. Wat Thepitakpunnaram, Pakchong, Nakhon Ratchasima: CUMZ 1583. Tam Pu Loop, Phuphaman, Khon Kaen: CUMZ 1526. Namprom Dam, Khon Kaen: CUMZ 1584.

Shell: This nominotypical subspecies is characterized by the large shell size (Table 2). Shell with last whorl and penultimate whorl purple to black; first to third whorls distinct yellow to bright orange. Lip expanded, red to orange.

Radula: Taenioglossate radula, teeth arrangement with central, lateral and marginal teeth shape similar to Pollicaria myersii. Differences include a central tooth with well developed central cusp and lateral cusp on each side; lateral teeth triangular in shape with a pointed tip; inner marginal teeth composed of 3 cusps; central cusp flanked with small inner and outer lateral cusps.

This subspecies occupies the southern limit of the species’ range in Cambodia and several localities in Loei, Phitsanulok, Chaiyaphum, Khon Kaen, Phetchabun Nakhon Ratchasima and Saraburi Provinces in Thailand.

The characters distinguishing this nominotypical subspecies from Pollicaria myersii are the smaller shell size and mainly purple coloured shell with whorls 2-3 pale to bright orange and bright orange to red lip (Tables 1, 2), and a distinct karyotype pattern (Kongim et al. 2009, 2010).

Holotype: CUMZ 1577 (Fig. 4J; height 34.5 mm, width 18.4 mm, 6½ whorls) from the type locality, paratypes CUMZ 1548 (Fig. 4K; 9 shells), 1561 (82 shells), 1562 (85 shells); NHMUK 20130073 (5 shells); MNHN IM-2012-2103; SMF341492 (5 shells).

Limestone outcrop with dry forest at Wat Tam Pha Bing, Wungsapoong District, Loei Province, Thailand (17°14'1.3"N, 101°44'3.5"E).

Phakeng-Phanang, Loei: ZMMSU 0025, 0026. Phu Luang Wildlife Sanctuary, Loei: CUMZ 1524. Phu Phalom, Muang, Loei: CUMZ 1547, 1560, 1565, 1567, 1580. Phu Phasamyod, Loei: ZMMSU 0011. Tam Erawan, Wungsapoong, Loei: CUMZ 1555, 1579. Tam Pha Bing, Wungsapoong, Loei: CUMZ 1548, 1561, 1562, 1577, ZMMSU 0001, 0004, 0006, 0017, 0028. Tam Pha Singh, Wungsapoong, Loei: CUMZ 1543, 1546. Wat Po Thi-sat, Nonghin, Loei: CUMZ 1557. Wat Tam Kuhawari, Nonghin, Loei: CUMZ 1540, 1549. Wat Tam Pha Mak-ho, Wungsapoong, Loei: CUMZ 1530, 1542. Wat Tam Pha Poo, Loei: CUMZ 1545, 1550. Wat Tam Piya, Loei: CUMZ 1527. Khao Wungpha, Nawung, Nongbua Lumphoo: CUMZ 1563, 1564. Nawung, Nongbua Lumphoo: CUMZ 1581. Tam Suwankuha, Nongbua Lumphoo: ZMMSU 0007.

From the Greek monos = one or single, and chroma = color of the skin; referring to the characteristic uniform dark brown to blackish spire color of the shell.

Shell: Shell relatively small, pupoid, monochrome purple to black. Periostracum thin and transparent. Whorls 5-6; sutures moderately impressed; apex obtuse; spire short. Last whorl large about two-thirds of shell height, flattened in front. Shell surface rough with malleations on upper half of last whorl. Aperture almost circular, shallow posterior angled groove present; peristome continuous, yellow to pale orange. Lip thickened, broadly expanded; umbilicus narrow. Operculum thick, calcareous, concentric, exterior little concave.

Radula: Taenioglossate radula, teeth arrangement with central, lateral and marginal teeth shape similar to the nominotypical subspecies.

Pollicaria mouhoti monochroma ssp. n. is restricted to the northern limit of the species’ distribution in Loei, Phetchabun, Chaiyaphum and Nongbua Lumphoo Provinces.

Pollicaria mouhoti monochroma ssp. n. can be distinguished from the nominotypical subspecies by having a much smaller, entirely black to purple shell (Tables 1, 2) and a distinct karyotype pattern (see Kongim et al. 2009, 2010). The shell size and shape of this subspecies are similar to that of Pollicaria gravida and Pollicaria crossei, but the purple shell is a distinguishing characteristic.

Shell character variations can be observed in the Phu Pha Lom, Loei Province population. These individuals exhibit a relatively larger shell than the typical populations (Table 2), however, the monochrome black shell and similar karyotype pattern indicate that they belong to this subspecies (Kongim et al. 2009).

Five lots with 13 specimens of syntype deposited in MNHN, the specimen figured in the original publication is designated as the lectotype of Hybocystis elephas Morgan, 1885 MNHN 21309 (Fig. 5A), paralectotype MNHN 21310 (5 shells), 21311 (2 shells), 21312 (3 shells), 21313 (2 shells), RBINS 525391 (1 shell). Single syntype specimen is designated as the lectotype of Hybocystis jousseaumei Morgan, 1885 MNHN 21308 (Fig. 5B). Ipoh, Perak, Malaysia: ZMA E.A. Meene colln. Acc. no. 1982 (1 shell). Near bridge over river, road Ipoh to Tanjong Rambutan, Perak, Malaysia: ZMA J. Drijver colln. (5 shells). Perak, Malaysia: ZMB 75821 (2 shells), 38044 (1 shell), M. Schulz colln. 1216 (3 shells, smallest shell excluded). Bukit Chintamani, Selangor, Malaysia: CUMZ 1534. Gunung Kenting, Ampang Baru, Ipoh, Perak, Malaysia: CUMZ 1535, 1536 (Fig. 5C), 1566, 1570.

Shell: Shell large, elongate pupoid uniform yellow to orange. Periostracum thin, corneous; shell surface with fine growth lines and last whorl with distinctly strong pitting dorsally. Whorls 6-7 whorls; sutures impressed; apex obtuse. Last whorl large about two-third of shell height, flattened in front. Aperture rounded, with shallow to deep posterior angle groove. Peristome continuous, little elevated, yellow to orange, internal parietal declining shoulder absent. Lip thickened, duplicated, and with distinct growth ridges; umbilicus narrow. Operculum thick, calcareous, concentric.

Radula: Taenioglossate radula, teeth arrangement with central, lateral and marginal teeth shape similar to Pollicaria myersii. Minor differences are the well-developed central cusp with one to three small lateral cusps of the central tooth, and the slightly elongate and slender central cusp of the inner marginal teeth.

This species has a restricted distribution and is known only from limestone outcrops in Perak, Peninsular Malaysia (Morgan 1885a, b). Material collected for this study was from Kinta valley, Perak, and the southern part of the species’ historical range in Bukit Chintamani, Selangor, Peninsular Malaysia is considered to be this locally endemic species.

The locally endemic Pollicaria elephas is confined to a few limestone outcrops in Peninsular Malaysia and shows several unique shell characters that separate it from its congeners. The major distinguishing characters of this species are the very large, monochrome yellowish to pale orange shell with the last whorl distorted ventrally and sculptured with scattered, deep pits dorsally; and rounded and thickened aperture. (Table 2, Fig. 5A–C).

Morgan (1885a, b) proposed two nominal species of Pollicaria from Perak, which differed mainly by the shell size (larger shell Hybocystis elephas and smaller shell Hybocystis jousseaumei). In the first revision of this genus, Crosse (1885) assumed that they were the same species and recognized only Pollicaria elephas. Thereafter Pollicaria jousseaumei was recognized as a synonym of Pollicaria elephas (Kobelt 1902, Pain 1974). Examination of the type specimens (Fig. 5A, B) confirmed Pollicaria jousseaumei as junior synonym of Pollicaria elephas. Moreover, the recent land snail survey in Perak, Peninsular Malaysia recorded both large and small shell forms of the species from the same localities.

Four specimens of the syntype deposited in MNHN, the figured specimen in original publication is designated here as the lectotype of Hybocystis rochebruni Mabille, 1887 MNHN 21305 (Fig. 5D) and other specimens as paralectotype MNHN 25855. Bac Ma National Park, Vietnam: CUMZ 1556. Hulien Nature reserve, Vietnam: CUMZ 1594. Khe Sen, Danang, Vietnam: CUMZ 1589. Phuong Nga National Park, Quang Binh, Vietnam: CUMZ 1523, 1539, 1552, 1568 (Fig. 5E). Cuc Phuong National Park, Ninh Binh, Vietnam: CUMZ 1532, 1568, 1573, 1587.

Shell: Shell medium-sized, pupoid, red-brown. Periostracum thick, corneous; shell surface smooth. Whorls 5-6; sutures moderately impressed; apex obtuse; spire short. Last whorl large about two-thirds of shell height, distorted and flattened in front, ventrally rounded. Aperture rounded, shallow to absent posterior angled groove present. Peristome continuous, with thin parietal declining shoulder internally. Lip thickened, little expanded, margin moderately duplicated with thin growth ridges; umbilicus narrow. Operculum concentric, thick, calcareous, multi-spiral plate.

Radula: Taenioglossate radula, teeth arrangement with marginal teeth shape similar to Pollicaria myersii. Major differences are in the central teeth which have multiple cusps: the central cusp relatively short and small, flanked by 1-3 tapered lateral cusps; and inner marginal teeth with 3 cusps: the central cusp large with a convex tip, flanked by small and pointed inner cusps, the outer lateral cusp very small to nearly wanting.

The previous records of this species were from Tonkin (Mabille 1887a, b); Babe National Park, Bac Kan, Vietnam (Yamazaki et al. 2007)

Based on the similarity in shell morphology, Pain (1974) placed Pollicaria rochebruni into the synonymy of Pollicaria gravida. However, examination of the type specimens of Pollicaria rochebruni indicate that it is a distinct species (see also Pollicaria gravida). Pollicaria rochebruni can be distinguished from the latter species by having a larger red-brown to purple-black shell with flattened whorls and shallow sutures, while Pollicaria gravida usually has smaller pale orange shell with convex whorls and impressed sutures (Tables 1, 2). Pollicaria rochebruni differs from the sympatric Pollicaria crossei in both shell size and colour (Tables 1, 2, Fig. 5F) as well as having a distinct karyotype pattern (see Kongim et al. 2010).

Single specimens of the syntype deposited in MNHN, the figured specimen in original publication is designated here as the lectotype of Hybocystis crossei Dautzenberg and ďHamonville, 1887 MNHN 21304 (Fig. 5F), and paralectotype RBINS 525390 (3 shells; the biggest one excluded). Cuc Phuong National Park, Ninh Binh, Vietnam: CUMZ 1521, 1522, 1588 (Fig. 5G), 1593. Hulien Nature reserve, Vietnam: CUMZ 1590.

Shell: Shell small, pupoid, bright orange. Periostracum thin, corneous; shell surface smooth. Whorls 5-6; sutures moderately impressed; apex obtuse; spire short. Last whorl large about two-thirds of shell height, distorted and flattened in front, ventrally rounded. Aperture rounded, with shallow to absent posterior angled groove. Peristome continuous, with thin parietal declining shoulder internally. Lip thickened, little expanded and duplicated; umbilicus narrow. Operculum thick, calcareous, concentric.

Radula: Taenioglossate radula, teeth arrangement with central, lateral and marginal teeth similar in shape to Pollicaria myersii.

The previous records of Pollicaria crossei was from Than-Moi, Tonkin and Cuc Phuong National Park, Ninh Binh, Vietnam (Dautzenberg and ďHamonville 1887, Vermeulen and Maassen 2003).

Pollicaria crossei has long been recognized as a subjective synonym of either Pollicaria rochebruni or Pollicaria gravida (Kobelt 1902, Pain 1974). However, the relatively smaller bright orange shell with thick, brown periostracum of Pollicaria crossei are a combination of characters that distinguish it from Pollicaria rochebruni. The bright orange shell with flattened whorls and shallow sutures distinguish it from Pollicaria gravida (Table 1, Fig. 3A). Moreover, the karyotypic study of the smaller shell form of Pollicaria gravida sensu lato indicated a distinct species recognized as Pollicaria crossei (see Kongim et al. 2010).