Limestone areas in Chonburi and Rayong provinces

We named this new species “burapha,” which means “eastern.” This refers to the type locality, which is located in the east and is also in honour of Burapha University, the workplace of the authors.

Holotype: Shell height 3.59 mm, shell width 1.91 mm. Aperture height 0.93 mm, aperture width 1.86 mm. Shell width/shell height ratio = 0.53. Aperture width/aperture height ratio = 1.15 (Fig. 2A).

Figure 2.  

Four Diplommatina species from eastern Thailand. A) Diplommatina crispata khaochamaoensis Panha et al., 1998, B) D. burapha sp. n., C) D. chadathongae sp. nov. and D) D. chantaburiensis sp. n. Each species shows a frontal view, lateral view, dorsal view and the number of ribs per 0.5 mm on the penultimate whorl and body whorl, respectively.

Figure 3.  

Two Diplommatina species from eastern Thailand. A) D. fusiformis spec. nov., B-E) D. khwantongae spec. nov., B) Holotype, C-D) Living snail. (Photos by Ms. Rattanawadee Tekavong). Each species shows a frontal view, lateral view, dorsal view and the number of ribs per 0.5 mm on the penultimate whorl and body whorl, respectively.

Paratypes: Shell height 3.59-4.35 mm (4.11 ± 0.11 mm) shell width 1.91-2.35 mm (2.21 ± 0.07 mm). Aperture height 0.93-1.19 mm (1.08 ± 0.06 mm). Aperture width 1.07-1.47 mm (1.39 ± 0.07 mm). Shell width/shell height ratio = 0.54 ± 0.02. Aperture width/aperture height ratio = 1.29 ± 0.05.

Shell minute dextral, elongated narrow, turreted with 7 ¾ round whorls that increase regularly in size and diameter until the last whorl; protoconch orange, smooth, consisting of 1 ¼ whorls, covered with minute pits; teleoconch light orange, consists of about 5 ¾ whorls that increase regularly in size and diameter until the last whorl; spires shouldered; sculpture consists of rather even and rather widely-spaced radial ribs with about 8 ribs/mm on the penultimate whorl and about 6 ribs/mm on the body whorl, the discernible spiral striae between the ribspresent; sutures deep; umbilicus closed; aperture round; peristome is thickened and expanded and doubled; columellar lamella rather bluntly rounded (Fig. 4).

Figure 4.  

Synopsis of eastern diplommatind species. A) Diplommatina crispata khaochamaoensis, B-C) Holotype and paratypes of D. burapha sp. n., D-E) Holotype and paratypes of D. chadathongae sp. n., F-G) Holotype and paratypes of D. chantaburiensis sp. n., H-I) Holotype and paratypes of D. fusiformis sp. n. and J-K) Holotype and paratypes of D. khwantongae sp. n. Scale bar = 1 mm.

Shell minute, dextral, turreted, translucent, whitish; protoconch smooth; teleoconch sculpture of widely-spaced radial ribs with discernible spiral striae between the ribs, Aperture rounded, columellar lamella well developed, peristome doubled, thickened and expanded.

We named this new species “burapha,” which means “eastern.” This refers to the type locality, which is located in the east and is also in honour of Burapha University, the workplace of the authors.

This species is known only from the type locality.

The size of the shell, shape of the shell and protoconch of D. burapha sp. n. are similar to D. doichiangdao Panha & Burch, 1998 from Doi Chiang Dao, northern Thailand and Laotian species, D. belonis Möllendorff, 1900. The spire of D. burapha sp. n. is relatively broader than that of those two species. The enlarged penultimate whorl and the body whorl of D. burapha sp. n. are relatively similar in diameter, while the last whorls of both D. doichiangdao and D. belonis are smaller in diameter than the enlarged penultimate whorl. This new species columellar is poorly developed, while well developed in D. doichiangdao and D. belonis.

Holotype. Shell height 1.61 mm, shell width 0.78 mm. Aperture height 0.50 mm, aperture width 0.60 mm. Shell width/shell height ratio = 0.49. Aperture width/aperture height ratio = 1.21 (Fig. 2C).

Paratypes (6 shells). Shell height 1.93-2.07 mm (1.98 ± 0.05 mm), shell width 0.84-0.93 mm (0.88 ± 0.03 mm). Aperture height 0.51-0.63 mm (0.58 ± 0.05 mm). Aperture width 0.59-0.67 mm (0.63 ± 0.02 mm). Shell width/shell height ratio = 0.45 ± 0.01. Aperture width/aperture height ratio = 1.09 ± 0.07.

Shell minute dextral, cylindrical, translucent, whitish, with about 5 ¾ whorls that increase regularly in size and diameter until the last whorl; protoconch orange, smooth, consisting of 1 ½ whorls; teleoconch light orange, consisting of about 4 ¼ keeled whorls; sculpture consists of strong, rather narrowly-spaced radial ribs which are about 20 ribs/mm on the penultimate whorl and about 14 ribs/mm on the body whorl; sutures well impressed; umbilicus closed; aperture round; peristome thickened and expanded and doubled; columellar lamella well developed and directed anteriorly (Fig. 4).

Shell minute, dextral, cylindrical, translucent, whitish, teleoconch sculpture of narrowly-spaced axial ribs, whorls aperture rounded, columellar lamella well developed, peristome thickened, expanded and doubled.

We named this new species “chadathongae” in memory of the second author's beloved mother, Ms. Wiang Chadathong.

Only known from the type locality.

Diplommatina chadathongae sp. n. is another one of the Thai smallest Diplommatina species (average shell height = 1.69 ± 0.04 mm) and same size as D. krabiensis Panha & Burch, 1998 (shell height of type specimens are 1.6-1.7 mm and average shell height = 1.69 ± 0.04 mm). This new species differs from D. krabiensis by its dextral, cylindrical, narrowly-fine radial ribs, while the smallest species is sinistral, shell fusiform or ovate with widely-spaced radial ribs. This new species differs from Diplommatina miriensis Godwin-Austen, 1917 from Nepal by its shell being more slender and columellar lamella well developed.

Holotype. Shell height 3.56 mm, shell width 1.64 mm. Aperture height 1.03 mm, aperture width 1.23 mm. Shell width/shell height ratio = 0.46. Aperture width/aperture height ratio = 1.19 (Fig. 2D).

Paratypes (7 shells). Shell height 2.56-2.85 mm (2.67 ± 0.10 mm) shell width 1.13-1.28 mm (1.24 ± 0.05 mm). Aperture height 0.73-0.85 mm (0.77 ± 0.06 mm). Aperture width 0.73-1.01 mm (0.93 ± 0.08 mm). Shell width/shell height ratio = 0.46 ± 0.02. Aperture width/aperture height ratio = 1.20 ± 0.13.Shell minute dextral, fusiform, translucent, whitish, with about 7 whorls that increase regularly in both size and diameter until the last whorl which is slightly smaller in diameter than the penultimate whorl; protoconch large, whitish, smooth, surface cover with minute pits, consisting of 1 ¼ whorls; teleoconch about 5 ¼ whorls, whitish; sculpture consists of thin, widely-spaced radial ribs which about 9 ribs/mm on the penultimate whorl and about 6 ribs/mm on the body whorl, discernible spiral striae between the ribs absent; sutures deeply impressed; umbilicus closed; aperture rounded; peristome thicked and expanded; columellar lamella is relatively small (Fig. 4).

Shell minute, dextral, translucent, whitish, protoconch large, teleoconch sculpture consisting of widely-spaced axial ribs, spiral striae between the ribs absent; aperture rounded, columellar lamella relatively small, peristome thickened and expanded.

The species name “chantaburiensis” refers to Chantaburi, the Province of the type locality.

Only known from the type locality.

Diplommatina chantaburiensis sp. n. is very similar to D. fusiformis sp. n. Nevertheless, D. chantaburiensis sp. n. has larger protoconch, shell more slender and no spiral striae between the radial ribs. This new species is also similar to the southern species D. hidagai Panha, 1998, but differs by its prominent protoconch, more widely-radial ribs and columellar lamella is poorly developed.

Holotype. Shell height 2.66 mm, shell width 1.22 mm. Aperture height 0.76 mm, aperture width 0.94 mm. Shell width/shell height ratio = 0.46. Aperture width/aperture height ratio = 1.23 (Fig. 3A).

Paratypes (5 shells). Shell height 2.66-2.74 mm (2.65 ± 0.07 mm) shell width 1.21-1.29 mm (1.25 ± 0.03 mm). Aperture height 0.76-0.87 mm (0.78 ± 0.06 mm). Aperture width 0.82-0.98 mm (0.91 ± 0.06 mm). Shell width/shell height ratio = 0.47 ± 0.02. Aperture width/aperture height ratio = 1.18 ± 0.10.

Description. Shell minute dextral, fusiform, translucent, light orange, with about 6 ½ whorls that increase regularly in size and diameter until the last whorl which is slightly smaller in diameter than the penultimate whorl; protoconch orange, smooth, consisting of 1 ¼ whorls; teleoconch light orange, about 5 ¼ whorls; sculpture consists of thin, widely-spaced radial ribs with discernible spiral striae between the ribs; there are about 10 ribs/mm on the penultimate whorl and about 8 ribs/mm on the body whorl; sutures deep; umbilicus closed; aperture rounded, peristome thickened and expanded; columellar lamella relatively small (Fig. 4) .

Diagnosis. Shell minute, dextral, translucent light orange, teleoconch sculpture consisting of widely-spaced axial ribs with spiral striae between the ribs; aperture rounded, columellar lamella relatively small, peristome, thickened and expanded.

We named this new species “fusiformis” based on its fusiform shell shape.

Only known from the type locality.

Diplommatina fusiformis sp. n. is similar to the southern species, D. hidagai Panha, 1998, but it differs by its more widely-ribbed shell, its more slender spire and its less prominent columellar lamella.

Holotype- Shell height 3.59 mm, shell width 1.91 mm. Aperture height 0.93 mm, aperture width 1.86 mm. Shell width/shell height ratio = 0.53. Aperture width/aperture height ratio = 1.15. (Fig. 3B-E).

Paratypes: (6 shells). Shell height 1.68-1.76 mm (1.69 ± 0.04 mm), shell width 0.78-0.81 mm (0.81 ± 0.04 mm). Aperture height 0.46-0.58 mm (0.53 ± 0.04 mm). Aperture width 0.53-0.61 mm (0.59 ± 0.03 mm). Shell width/shell height ratio = 0.48 ± 0.03. Aperture width/aperture height ratio = 1.12 ± 0.07.

Shell minute dextral, cylindrical, light orange, with about 7 whorls that increase regularly in size and diameter until the last whorl; protoconch orange, smooth, consisting of 1 ¼ whorls, covered with minute pits; teleoconch light orange, consisting of about 5 ¾ whorls; spires shouldered; sculpture consists of rather even and widely-spaced thin radial ribs with discernible spiral striae between the ribs; there are about 8 ribs/mm on the penultimate whorl and about 6 ribs/mm on the body whorl; sutures deep; umbilicus closed; aperture round; peristome thickened and expanded and doubled; columellar lamella rather bluntly rounded.

Animal. Living animals had a greyish body, head, tentacles and foot, with an orange eye located at the base of each tentacle (Fig. 3C-E). The operculum was round and corneous. Snails were found living in leaf litter and plant debris in the limestone hills. Due to the small population of each species, the live specimens of all species found in this study are hard to find. More observation and further study on anatomy are needed.

Shell minute, dextral, cylindrical, light orange, teleoconch sculpture of widely-spaced and high radial ribs, aperture rounded, columellar lamella well developed, peristome thickened and expanded.

We named this new species “khwantongae” in memory of Ms. Kanita Khwantong, who made the first discovery of this new species.

This species is known only from the limestone hills in Chonburi and Rayong Provinces.

The shell shape of Diplommatina is generally fusiform or tower-shaped with mostly low and strong radial ribs, which are formed as tubular projections in some species and mostly rounded or angular periphery whorls. For example, the shell of D. hidagai is fusiform covered with low and strong radial ribs or the shell of D. nimannandhi Panha et al., 2002 has tower-shaped, radial ribs forming as semi-tubular peripheral projections. In this new species, Diplommatina khwantongae sp. n. is a very distinct species of epitoniid snail due to its cylindrical, thin radial ribs and shouldered whorls.