Bertia cambojiensis (Reeve, 1860)

Sutcharit, Chirasak, Naggs, Fred, Ablett, Jonathan, Sang, Pham Van, Luong Van Hao, & Panha, Somsak, 2019, Notes on the sinistral helicoid snail Bertia cambojiensis (Reeve, 1860) from Vietnam (Eupulmonata, Dyakiidae), ZooKeys 885, pp. 1-14 : 1

Bertia cambojiensis (Reeve, 1860) Figs 1 , 2

Helix mouhoti Reeve, 1860a [Sep.]: 203, 204 [not Pfeiffer 1860a [May]: 136, pl. 50 fig. 5]. Type locality: Cambojia [Cambodia]. Pfeiffer 1860b: 173, 174, pl. 47, figs 1, 2. Pfeiffer 1868: 64.

Helix cambojiensis Reeve, 1860b [Dec.]: 455 [new replacement name]. Martens 1867: 76. Pfeiffer 1868: 64. Daniel 1869: 126-128. Morelet 1875: 250. Pfeiffer 1876: 78, 79. Pfeiffer and Kobelt 1881: 604, pl. 176, figs 1, 2. Tryon 1886: 18, pl. 6, fig. 9.

Helix cambodjensis : Mabille and le Mesle 1869: 128 [incorrect subsequent spelling].

Nanina cambodgiensis : Ancey 1887: 53 [incorrect subsequent spelling]. Fischer and Dautzenberg 1904: 393.

Ariophanta (Rhyssota) cambojiensis : Fischer 1891: 23.

Bertia cambodjiensis : Abbott 1989: 127 with text figure [incorrect subsequent spelling].

Bertia cambojiensis : Schileyko 2003: 1362, fig. 1777. Schileyko 2011: 37. Thach 2016: 142, fig. 271.

Material examined.

Two syntypes from the Cuming collection. The specimen figured by Pfeiffer (1860b: pl. 47, figs 1, 2) can be recognised by two broken growth lines; one on the border of penultimate and last whorls, and one on the last whorl close to the apertural lip (seen from umbilical view) and is here designated as the lectotype NMUK 20130220 (height 54.6 mm, width 76.2 mm; Fig. 1A ). The remaining paralectotype NHMUK 20130219 measures height 54.4 mm and width 73.6 mm.

All additional specimens were from the area of Cat Tien National Park, Dong Nai Province, Vietnam (11°26.147"N, 107°25.643"E): NHMUK 20130818 from Lodge Gardens (4 specimens + 2 juveniles); NHMUK 20130833 from Cave Site (7 specimens + 1 juvenile; Fig. 1B ; COI accession no. MN296022, 16sRNA accession no. MN296390); NHMUK 20130874 from Near Lake (6 specimens + 3 juveniles; COI accession no. MN296023, 16sRNA accession no. MN296391 and 28S accession no. MN296349). Measurements: shell height 49.9-55.7 mm, average 52.6 mm; shell width 64.4-74.5 mm, average 69.7 mm.

Description.

Shell. Shell sinistral, large, dome shape and thickened. Whorls 6 to 7, increasing regularly, slightly convex, and with wide and shallow suture. Periostracum thin to slightly thickened, corneous. Spire convex, apex obtuse, embryonic shell large with smooth surface, following whorls possess a series of thin nodules on growth lines. Last whorl well rounded. Upper shell surface glossy, varying from rich cream and brownish to blackish bands; narrow pale white to yellowish spiral band on periphery; narrow reddish-brown to dark subsutural band. Below periphery always with reddish-brown to dark colour and with broad white spiral band surrounding umbilicus. Umbilical area usually reddish-brown or darker. Aperture ovate; parietal callus translucent whitish; columella thickened and slightly dilated. Lip simple or slightly thickened in old adults. Umbilicus narrowly perforate to rimate and deep.

Genital organs. Atrium (at) very short (N = 2). Penis (p) long cylindrical tube. Penial retractor muscle (pr) short, thickened and attached distally to penis. Epiphallus (e) cylindrical tube, about half of penis length and slightly smaller diameter than distal penis. Vas deferens (vd) relatively smaller diameter and thin tube extending from free oviduct (fo) and entering epiphallus, apically; flagellum absent ( Fig. 2A ). Internal wall of penis with large penial pilasters (pp) for nearly entire length of chamber; proximally with smooth surface and distally with very thin crenellations on surface; penial verge absent ( Fig. 2B ).

Gametolytic organ (go; duct and sac undifferentiated) proximal to genital opening about one-fourth of amatorial organ length. Slightly swollen proximally, then tapering to small, long cylindrical tube and attached to ovary with thin connective tissues. Amatorial organ (am) well-developed enlarged cylinder; proximally attached to atrium. Amatorial organ glands (amg) enlarged, composed distally of four major lobes bounded to amatorial organ by thin connective tissue. Each of four major lobes of the amatorial organ gland extend proximally into thick amatorial organ ducts (amd) that are twisted together and bound with thin connective tissue before entering the distal tip of the amatorial organ ( Fig. 2A ). Internal wall sculpture of amatorial organ: proximally smooth surface for about one-third of chamber; distally consists of smooth surface of enlarged longitudinal amatorial organ pilasters (amp). Amatorial organ papilla small, short and conical, tipped by a large and long blackish spike ( Fig. 2C ).

Vagina (v) long enlarged cylinder, about the same length as penis. Free oviduct (fo) cylindrical tube; oviduct (ov) long with lobules; prostate gland (pg) bound to oviduct. Most of albumen gland, hermaphroditic duct and gland missing from figured specimen ( Fig. 2A ). Internal wall of vagina sculptured with uniform scale-like or triangular lingulate pilasters (vp), varying in size from small to large ( Fig. 2D ).

Radula . Teeth arranged in wide angle V-shaped rows with approximately 245 teeth with formula ((124-118)-1-(120-122)). Central tooth symmetric unicuspid and triangular. Lateral and marginal teeth undifferentiated, slightly curved unicuspid, triangular, and inclined towards central tooth ( Fig. 2E ). Inner teeth similar in shape and size to central teeth and then gradually reducing to slender and elongate sword-shaped with pointed cusp; outermost teeth slightly shorter with pointed tip ( Fig. 2F ).

External features. Living snail with long, blackish-brown tentacles. Skin reticulated brown with black reticulations around head. Foot sole relatively elongated, broad and unipartite. Sole of foot brownish to orange and unspotted; side of body brownish. Tail curved mid-dorsally, tall dome-shaped in cross section. Caudal horn not overhanging; caudal foss long vertical slit in tail above sole margin. Typical aulacopoda with well-defined pedal groove.

Mantle collar large and shell lobes thickened, shell lappet absent. Right dorsal lobe (right side of anus) large and thickened. Left dorsal lobe (left side of anus) composed of thick crescentric anterior left dorsal lobe and thin elongated posterior left dorsal lobe. Pulmonary cavity typically sigmurethran.

Distribution.

The range of B. cambojiensis is likely to be confined to localised forest patches within Dong Nai, Binh Thuan, Lam Dong and Binh Phuc provinces. Records far outside of this range such as Ba Vi National Park ( Schileyko 2011) are very doubtful and to date, no specific localities have been recorded for Cambodia.

Remarks.

The specimens from southern Vietnam that we examined exhibit clear differences in genital anatomy from those described by Schileyko (2003: 1362, fig. 1777b, c) that were based on a specimen in the Muséum National ďHistoire Naturelle, Paris, recorded from Cambodia. The Paris specimen exhibits a long, cylindrical gametolytic duct (spermathecal stalk in Schileyko) and a bulbous gametolytic sac (receptaculum seminalis in Schileyko), distally pointed. The amatorial organ contains numerous amatorial organ ducts. In the NHM specimens the gametolytic duct is short and the amatorial organ includes four amatorial organ ducts. On the basis of numerous studies in the reproductive anatomy of pulmonate snails, these character differences strongly suggest species level distinction. The shell of the Paris specimen was not figured by Schileyko, his figured shell of B. cambojiensis (fig. 1777a) being from the Naturalis Museum, Leiden, which was also recorded as being from Cambodia.

In December 1858, the French explorer and naturalist Henri Mouhot set off from Bangkok by sea to the port of Komput (Kampot), Cambodia, from where he continued on his destination to Brelum in Annam (Vietnam), He reached the Catholic Mission in Brelum in August 1859. Stuart et al. (2006) state that Brelum was considered to be within the confines of Cambodia at the time of Mouhot’s visit. However, Mouhot (1864a: 237) unequivocally described how 'It took us two long days’ journey to reach Brelum’ after having passed the Cambodian border town of Pump-Ka-Daye. Brelum was Mouhot’s collecting base for the following three months before setting off on his return journey in November ( Mouhot 1864a). During his stay in Brelum his host, the missionary R.P. Guillon, wanted Mouhot to sample the local escargot, which proved to be B. cambojiensis . Staggered by the beauty of this snail Mouhot set about obtaining examples for his collections from the local area, where it was abundant ( Daniel 1869). Daniel (1869) went on to state that B. cambojiensis had not been found in Cambodia. Historical records may all relate to the mistaken assumption that the type locality was Cambodia. Mouhot was dependant on the sale of his collections to finance his fieldwork and it is likely that he shipped a large number of specimens of B. cambojiensis to his agent in London, Samuel Stevens, who would have sold them on to museums and collectors throughout Europe, presumably labelled with the locality ‘Cambodia’. The field and travel conditions impacted severely on Mouhot’s collections and he clearly had insufficient time to arrange them in good order before they were shipped. Writing to Stevens from Pinhalu, near Phnom Penh, on 20th December, 1859 Mouhot (1864b: 248) commented: ‘… I have little time to give you any details as to what I despatch from Komput and Singapore’.

According to Ashburton (1864), the location of Brelum, the type locality, is 11°58"N, 107°12"E, which is at an altitude of 460 m (Google Earth). This location is 30 km north of the north-western boundary of Cat Tien National Park and some 94 km north and west of the entrance to Cat Tien National Park. However, there remains some doubt as to the exact location of Brelum. Under the heading of a letter to Stevens, Mouhot (1864b: 241) stated: 'Brelum, among the savage Stiêns, lat, 11°46'30"N, 103°3'W merid. of Paris, 15th October, 1859'. This is clearly wrong because in addition to W (west) it should be E (east) and in the following text he gives exactly the same geo-reference for Pinhalu that he states to be about nine miles from the capital, Phnom Penh 11°46'58"N, 104°22'59"E (Google Earth) whereas Mouhot’s reading 11°46'30"N, 103°3'W Paris (= 2°20'14.03" east of Greenwich) = 105°23'14"E, is some 54 km to the east and north of Phnom Penh (Google Earth). Kottelat and Tan (2017) identify Bro Lam Phe, 11°56'N, 106°40'E, in Loc Ninh District, Binh Phuoc Province, Vietnam, as the location of Brelum. This places Brelum at 100 m altitude and only 2 km from the closest boundary with Cambodia, which at this point follows the course of a meandering tributary of the Mekong. It is some 70 km from the boundary of Cat Tien National Park and 100 km from the main park entrance. It seems that Mouhot would have been most unlikely to retrace his steps and cross the river into Cambodia before his return journey and we conclude that he only collected B. cambojiensis from the vicinity of Brelum in Vietnam. Nevertheless, being in close proximity to the Cambodian border it does seem likely that B. cambojiensis will occur in this area of Cambodia.

Figures

Figure 1. Shells of Bertia cambojiensis A lectotype NHMUK 20130220 and B specimen NHMUK 20130833.

Figure 2. Genitalia and radula of Bertia cambojiensis, NHMUK 20130833. A overview of genital system B-D internal wall sculpture of B penis C amatorial organ and D vagina E, F SEM image of radula E central and inner latero-marginal teeth and F outermost teeth. Numbers indicate tooth order from lateral to marginal end; central tooth indicated by ' C'.