Neocepolis morleti ( Dautzenberg and d’Hamonville, 1887 )

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 : 628-629

Neocepolis morleti ( Dautzenberg and d’Hamonville, 1887)

( Figures 1C, D , 2B , 3 D–F, 5E–H)

Helix morleti Dautzenberg and d’Hamonville 1887, p. 217 , Plate 8 Figure 3 . Type locality: road from Bach Ninh to Lang Son, Tonkin; Pilsbry 1891, p. 240, Plate 65, Figures 80, 81.

Helix mercatorina Mabille 1887, p. 88 , Plate 2 Figures 10, 11. Type locality: Tonkin; Pilsbry 1890, p. 121, Plate 15 Figures 67, 68.

Neocepolis morleti: Pilsbry 1891, p. 312 (figure legend).

Obba morleti: Pilsbry 1891, p. 323 (figure legend).

Camaena (Neocepolis) morleti: Pilsbry 1894, p. 107 .

Material examined

Than Moi, Tonkin, Vietnam, Lectotype MNHN ( Figure 1C ). Tonkin, Vietnam: MNHN (10 lots). Tonkin, Vietnam: SMF 26527, 297152 , 297153 . Huu Lien Nature Reserve, Lang Son Province, Vietnam: CUMZ 2553 , 2554 , 2256 ( Figure 2D ), 2558. Cuc Phuong National Park , Ninh Binh Province, Vietnam: CUMZ 2257 .

Measurements

See Table I.

Shell

Shell depressed-globose, somewhat thin, umbilicate, corneous or whitish; periostracum thin and corneous; surface with close, regular ribs and rather smooth below periphery. Embryonic shell small and smooth ( Figure 2B ). Spire slightly flattened to elevated; apex obtuse to slightly acute; sutures weakly impressed. Whorls 5 7 / 8 –6 1 / 2 increasing regularly. Last whorl shouldered to convex. Aperture round, brownish inside. Peristome subcircular, subvertical, descending slightly; parietal callus thin and pellucid to brownish. Lip brownish, expanded, and thickened with a slight reflection. Columella curved, brownish, slightly expanded at base, and an obtuse columella tooth, corresponding to shallow external depression ( Figure 1C, D ).

Radula

Each row contains about 70 (35-(18-20)-1-(17-19)-34) teeth. Central tooth, lateral teeth and marginal teeth ( Figure 3 D–F) similar to those of N. merarcha .

Jaw with strong and prominent vertical ribs, variable in number, very thin transverse growth lines present ( Figure 5E ).

Pallial system

Typically sigmurethrous; the structure of kidney and lung similar to that of N. merarcha .

Genitalia

Atrium relatively long (n 53). Penis long cylindrical; proximally enlarged and curved at penial verge; distally tapering to narrow tube. Epiphallus (e) narrow and short; flagellum (fl) relatively long, almost the same size as epiphallus. Vas deferens (vd) a small tube extending from free oviduct to distal epiphallus. Penial retractor muscle relatively long ( Figure 5F ).

Internal wall of penis corrugated and exhibiting a series of thickened and swollen transverse and longitudinal pilasters, which form a fringe around penial verge tip. Penial verge very large, long conic, curved and with nearly smooth surface. Longitudinal pilasters proximal to genital orifice possesses thin to nearly smooth ridges ( Figure 5G ).

Vagina (v) narrow, cylindrical and longer than penis, held in position by series of muscles originating from foot floor and inserted on external wall of vagina. Gametolytic duct (gd) long, extending from vagina as a proximally enlarged cylindrical tube; abruptly tapering distally to narrow tube connected to gametolytic sac (gs). Free oviduct (fo) relatively long; oviduct (ov) compact and enlarged to form lobular alveoli. Albumen gland (ag) curved ligulate ( Figure 5F ). Hermaphroditic duct (hd) contracted, convoluted and connected proximally to talon head (ta) ( Figure 5H ).

Internally, vagina possesses several longitudinal pilasters (vp), proximally with slightly corrugated and ridged surface transforming distally into smooth-surfaced ridges ( Figure 5G ).

Distribution

N. morleti was previously known only from along the road between Bach Ninh and Lang Son Provinces ( Dautzenberg & d’Hamonville 1887; Mabille 1887; Pilsbry 1891). Our specimens were collected from Huu Lien Nature Reserve, Lang Son Province, a limestone karst area about 90 km north of Hanoi, and from Cuc Phuong National Park, Ninh Binh Province, about 160 km south of Hanoi.

Remarks

Pilsbry (1891) considered that N. morleti was closely related to Camaena platyodon (Pfeiffer, 1846) ; the two species sharing the similar shell characters of a depressed shell, toothed columella and descending aperture. Our observations of the genitalia, especially the long penis, large penial verge, triangular central tooth, and ribbed jaw are consistent with there being a close relationship between these two species. However, N. morleti differs from C. platyodon in having a quite distinct shell form which is monochrome with a ribbed surface, a longer vagina and a transverse penial pilaster (Pilsbry 1891; this study).

The body and head wart in the preserved specimens of N. morleti are similar to the former species in almost all characters. Only the slightly light brownish skin and lung roof differ from that of the N. merarcha .

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 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.