Conulinus randalanai, Griffiths & Herbert, 2013

Griffiths, O. L. & Herbert, D. G., 2013, New species of land snails (Mollusca: Gastropoda) from two isolated karst formations in central western Madagascar: Tsingy Beanka and Antsingimavo, with additional notes on other regional endemics, African Invertebrates 54 (1), pp. 1-48 : 15-16

Conulinus randalanai sp. n.

Fig. 10

Etymology: Named for Roger Randalana, on-site manager of the Tsingy Beanka reserve and participant in many malacological expeditions throughout Madagascar.

Diagnosis: Shell bulimiform, whorls relatively elongate, body whorl comprising approx. 66% of total shell height; spire profile cyrtoconoid; columella reflected, umbilicus narrow; sculptured by microscopic axial riblets and even finer spiral threads; lustreless, mauve-brown, paler apically.

Description:

Shell: Elongate-bulimiform, thin; body whorl comprising approx. 66 % of total shell height; spire profile cyrtoconoid, suture not strongly indented; whorls weakly convex, base a little more strongly so, periphery rounded; umbilicus reduced to a narrow tube-like channel by reflected upper portion of columella lip. Protoconch of approx. 1¼ whorls, smooth. Teleoconch of a further 4¾–5 whorls; appearing smooth, but microsculptured by numerous, very fine, close-set axial riblets, and even finer microscopic spiral threads; axial riblets becoming less regular with growth and resembling fine, uneven growthlines on last adult whorl, spiral sculpture persisting throughout and extending on to base. Aperture elongate-ovate; somewhat oblique to vertical axis of shell; peristome incomplete, simple and thin; no subterminal thickening evident inside outer lip; upper part of columella reflected and compressed against preceding whorl such that its edge is narrow (pleat-like in some specimens) and the umbilicus restricted to a very narrow, tube-like channel.

Shell somewhat lustreless rather than glossy; predominantly mauve-brown in the freshest specimens, with some axial variations in intensity particularly on middle spire whorls; paler pinkish brown to fawn apically.

Dimensions: Holotype, height 16.9 mm, max. diameter 8.5 mm; largest specimen, height 17.5 mm.

Holotype: MADAGASCAR: Central W Madagascar, ca 60 km E of Maintirano, E of Belitsaka , E part of Tsingy Beanka , 18.06145°S 44.52595°E, ca 450 m, in leaf-litter and tsingy slots in comparatively lush tall dry deciduous/evergreen forest on south-facing hill, 2.x.2006, O. Griffiths, R. Randalana, D. Herbert & L. Davis, st’n 12/06 ( AMS C.469591).

Paratypes: St’n R 02/10 ( NMSA L8469 /T2897, 1 specimen; AMS C.469584, 4 specimens; MNHN IM-2010-20069, 1 specimen) .

Additional locality data: Tsingy Beanka : st’ns 03/10, 11/10.

Distribution: Evidently a narrow-range endemic; known only from the Tsingy Beanka .

Habitat: Fresh dead shells have been found in tall, relatively lush dry deciduous and evergreen forest. No living specimens known.

Remarks:The only comparable species known from Madagascar is C. rufoniger (Reeve, 1849) , but that species differs in having more rounded whorls, a less elongate shape and a darker, chestnut brown colour ( Fig. 7D, E ). It also lacks spiral sculpture, and has a wider umbilicus and a thickened white varix inside the outer lip at maturity. C. rufoniger has been mostly recorded from north-eastern Madagascar (Fischer-Piette et al. 1994), but we can also confirm its presence at Antsingimavo (st’ns 04/06, 06/06), Tsingy Beanka (st’ns 01/09, 02/09, 09/09) and in the Tsingy de Bemaraha (Manombolo River).

In the absence of anatomical data, our referral of this species to Conulinus is tentative. In its shape and spiral microsculpture, C. randalanai also resembles some species of Rachis Albers, 1850 , but it lacks the colour pattern of dark spots and/or spiral bands commonly seen in species of that genus. Indeed, the referral of C. rufoniger to Conulinus also requires confirmation.

Figures

Fig.10. Conulinus randalanai sp.n. and C. rufoniger (Reeve, 1849): (A, B) C. randalanai, holotype, height 16.9 mm, AMS C.469591; (C) C. randalanai, paratype, height 17.5 mm, NMSA L8469/T2897; (D–E) C. rufoniger, Diego Suarez [Antsiranana] district, 8 km south of Orangea, height 18.6 mm, NMSA L8443.

Fig. 7. Tropidophora secunda Fischer-Piette & Bedoucha, 1965: (A–C) Tsingy Beanka, st’n 03/06, max. diameter 21.5 mm, NMSA L7040;(D) Tsingy Beanka, st’n 03/06, subadult, max.diameter 20.0 mm, NMSA L7040;(E) Kelifely Plateau, max.diameter 18.8 mm,NMSA L6798; (F–H) holotype (faded), ‘Madagascar’, Cuming collection, max. diameter 22.0 mm, NHMUK 20110470.