Neocepolis Pilsbry, 1891

Sutcharit, Chirasak, Naggs, Fred & Panha, Somsak, 2007, Systematic review of the land snail genus Neocepolis Pilsbry, 1891 (Pulmonata: Camaenidae) from north Vietnam, Journal of Natural History 41 (9 - 12), pp. 619-631 : 620-628

Genus Neocepolis Pilsbry, 1891

Type species. Helix merarcha Mabille, 1888 by original designation in Pilsbry 1891, pp. 234, 235.

Diagnosis

Shell brown to corneous, globose to depressed, dextral, umbilicate or rimate; surface with striate growth lines. Aperture slightly rounded and descending; lip thickened and expanded; parietal callus thin and transparent. Columella straight, slightly dilated and with obtuse tooth; typically with strong fold inside outer lip, represented externally by a deep longitudinal groove. Genitalia possess large or small penial verge, long penis and vagina, and short epiphallus and flagellum. Radula possesses a unicuspid and triangular central tooth, bicuspid lateral teeth, tricuspid marginal teeth; ribbed jaw. Pallial anatomy sigmurethrous.

Remarks

Neocepolis is known only from Tonkin ( Dautzenberg & d’Hamonville 1887; Mabille 1887, 1888; Pilsbry 1891). Species records outside of Tonkin (sensu Pilsbry 1891) are either misidentifications or incorrect generic attributions to the camaenids Chloritis Beck, 1837 , Camaena , Oreobba Pilsbry, 1894 or the bradybaenid Phoenicobius Mörch, 1852 (Pilsbry 1894; Gude 1914; Zilch 1964; Richardson 1983, 1985). Neocepolis was diagnosed by possession of a toothed columella, external groove, ribbed surface and smooth embryonic shell (Pilsbry 1891, 1894). Our study demonstrates that Neocepolis has simple, camaenid type genitalia.

Neocepolis merarcha differs from N. morleti in exhibiting a slightly more dome-shaped, brownish shell, slightly narrower umbilicus and with a groove marked on the outside wall. The genitalia are very similar but, on the basis of material examined by us, N. merarcha possesses a slightly shorter atrium, smaller penial verge and penial wall without the transverse pilaster present in N. morleti .

Neocepolis merarcha ( Mabille, 1888)

( Figures 1A, B , 2A , 3 A–C, 4, 5A–D)

Helix merarcha Mabille 1888 , pp. 74, 75. Type locality: Halong , Tonkin; Pilsbry 1891, p. 235, 236, Plate 32 Figures 42–45.

Neocepolis merarcha: Pilsbry 1891, p. 315 (figure legend); Pilsbry 1894, p. 356 (figure legend).

Camaena (Neocepolis) merarcha: Pilsbry 1894, p. 107 , Plate 39 Figures 9, 10.

Helix (Obba) langsonensis Bavay and Dautzenberg 1899, p. 29 , Plate 1 Figures 1, 1a ; Type locality: Lang Son and That Khe´ , Tonkin .

Neocepolis cherrieri Bavay in Dautzenberg and Fischer 1908, p. 174 (footnote), Plate 4 Figures 6–12 (new name for Helix (Obba) langsonensis ); Zilch 1960, p. 607, Figure 2128; Zilch 1964, p. 246.

Neocepolis cherrieri var. edentula Dautzenberg and Fischer 1908, p. 174 , Plate 4 Figure 6.

Neocepolis cherrieri var. scrobiculata Dautzenberg and Fischer 1908, p. 174 , Plate 4 Figure 7.

Neocepolis cherrieri var. depressa Dautzenberg and Fischer 1908, p. 174 , Plate 4 Figure 8.

Neocepolis cherrieri var. depressascrobiculata Dautzenberg and Fischer 1908, p. 174 , Plate 4 Figures 9, 10.

Neocepolis cherrieri var. carinata Dautzenberg and Fischer 1908, p. 174 , 175, Plate 4 Figures 11, 12.

Material examined

Between Lang-Son and That-Khe´, Vietnam: Lectotype MNHN ( Figure 1A ). Tonkin, Vietnam: MNHN (7 lots). Tonkin, Vietnam: SMF 26528, 26529 , 91084 , 297150 , 297151 . Cuc Phuong National Park , Ninh Binh Province, Vietnam: CUMZ 2550 ( Figure 1B ), 2551, 2552, 2555, 2577, 2578, 3547.

Measurements

See Table I.

Shell

Shell globose, opaque and rimate; light brown; periostracum thin; surface with regular ribs, rather smooth below periphery. Embryonic shell small, surface smooth ( Figure 2A ). Spire dome shaped; apex obtuse; sutures shallow but slightly more impressed on last whorl. Whorls 6 K, slowly widening and increasing regularly. Last whorl evenly rounded or with very slight peripheral keel. Close to aperture, a transverse groove below the periphery corresponds with lamella inside outer lip. Aperture round, internally brownish. Peristome subcircular, subvertical, descending; parietal callus transparent. Lip whitish, expanded, slightly thickened with short reflection. Columella curved, brownish, expanded across umbilicus, and an obtuse columella tooth, marked externally by a shallow pit ( Figure 1A, B ).

numbers indicated in parentheses.

Radula

Teeth arranged in anteriorly pointed V-shaped rows, each row containing about 78 (39- (19-21)-1-(19-22)-38) teeth. Central tooth triangular, slightly concave on each side. Lateral teeth bicuspid; ectocone with small and pointed cusp; endocone large, triangular with pointed cusp ( Figure 3A ). Marginal teeth range from 19 to 22 ( Figure 3B ). Endocone very small and close to apex of mesocone; mesocone large with pointed cusp; ectocone located basally, with pointed cusp and a deep notch between it and mesocone. Outermost marginal teeth small, endocone and mesocone cusps sharp, ectocone with multiple pointed cusps ( Figure 3C ).

Jaw crescent shaped, with anteriorly convex cutting margin. Vertical ribs strongly prominent and variable in number ( Figure 5A ).

Pallial system

Typically sigmurethran and without mantle gland ( Figure 4A ). Heart (auricle (au) and ventricle (ve)) located left of kidney (on right in figure). Pulmonary cavity approximately five times longer than broad. Pulmonary vein (puv) and venation on lung (l) roof distinct and well developed. Kidney (k) elongated and slender, and extending from posterior of cavity for approximately one-third length of pulmonary cavity. Ureter (ur) sigmoid, closed tube arising from apex of kidney, extending along right side of kidney, recurving adjacent to rectum (r). Anus (a) adjacent to mantle collar (mc) ( Figure 4B ).

Genitalia

Atrium (at) short (n 54). Penis (p) cylindrical, long and reaching similar length to vagina; proximally enlarged; distally tapering to narrow tube. Epiphallus (e) narrow and short; flagellum (fl) slightly longer than epiphallus. Vas deferens (vd) a long and small tube, extending from free oviduct to distal epiphallus. Penial retractor muscle (pr) long and slightly thickened ( Figure 5B ).

Internally, penial verge (pv) small, conical and long; surface with thin longitudinal ridges and wrinkles. Penial wall ribbed, forming a series of swollen longitudinal pilasters (pp); proximally, wall relatively smooth. Smooth pilasters occupy the middle of the penial chamber and encircle tip of penial verge. ( Figure 5C ).

Vagina (v) a cylindrical tube held in position by series of muscle bands rising from foot floor. Gametolytic duct (gd) long; proximally broader and cylindrical; distally tapering to small, long tube and terminating with swollen gametolytic sac (gs). Free oviduct (fo) relatively long; oviduct (ov) enlarged with curled lobules. Albumen gland (ag) curved ligulate ( Figure 5B ). Hermaphroditic duct (hd) convoluted and connected to head of talon (ta) ( Figure 5D ).

Internal walls of vagina possess several smooth longitudinal vaginal pilasters (vp). Proximally with small crenulated ridges; distally becoming smooth-surfaced ridges ( Figure 5C ).

Other features

Preserved specimens of N. merarcha exhibit a long and narrow foot, blackish integument and mantle cavity, dorsally a pale stripe runs along the entire body length. The lung roof exhibits a uniform distribution of black pigmentation. All examined specimens exhibited a longitudinally divided head wart, located between the superior tentacles.

Distribution

Neocepolis merarcha has a restricted distribution, early records were from Ha Long, Lang Son and That Khe´, northern Vietnam ( Mabille 1888; Pilsbry 1891; Dautzenberg & Fischer 1908). Our material was collected from Cuc Phuong National Park, Ninh Binh Province in a limestone karst area covered with evergreen forest, located about 160 km south of Hanoi.

Remarks

Neocepolis merarcha as understood by us, exhibits a wide range of shell form, associated with several named ‘‘varieties’’ of uncertain status based on degree of shell elevation and nature of apertural barrier ( Dautzenberg & Fischer 1908). The material collected by us closely corresponds with the nominotypical form, distinguished from the other five ‘‘varieties’’ by possession of an elevated or dome-shaped shell and obtuse columella tooth ( Mabille 1888; Dautzenberg & Fischer 1908). Additional material is needed before the status of these ‘‘varieties’’ can be assessed meaningfully.

One specimen exhibited 22 mite-cysts on the lung roof and distributed from around the kidney base, being most abundant proximal to the pneumostome.

Figures

Figure 1. Neocepolis spp. from Vietnam, shells. (A) N. merarcha (Lectotype MNHN); (B) N. merarcha (CUMZ 2550) from Cuc Phuong National Park, Ninh Binh Province, Vietnam; (C) N. morleti (Lectotype MNHN); (D) N. morleti (CUMZ 2556) from Huu Lien Nature Reserve, Lang Son Province, Vietnam.

Figure 2. Neocepolis spp. from Vietnam, protoconch sculpture. (A) N. merarcha (CUMZ 2555); (B) N. morleti (CUMZ 2558).

Figure 3. Neocepolis spp. from Vietnam, radula: A–C. N. merarcha (CUMZ 2551); (D–F) N. morleti (CUMZ 2553). (A, D) Central tooth with the first to the second lateral teeth; (B, E) lateral teeth with the tricuspid marginal teeth transition; (C, F) outermost marginal teeth. Numbers indicate order of lateral and marginal teeth. Central tooth indicated by ‘‘C’’.

Figure 4. Neocepolis merarcha from Vietnam (CUMZ 2550). (A) Pallial complex; (B) pneumostome.

Figure 5. Neocepolis spp. from Vietnam, jaw and genitalia. A–D. N. merarcha (CUMZ 2551; May, 1999) and E–H. N. morleti (CUMZ 2553; May, 1999). (A, E) Jaws; (B, F) general view of genital system; (C, G) internal structure of penis, atrium and vaginal chamber; (D, H) a connection of hermaphroditic duct and talon.