Acroptychia bathiei Fischer-Piette & Bedoucha, 1965

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 : 5-7

Acroptychia bathiei Fischer-Piette & Bedoucha, 1965

Figs 2 , 3 , 25A

Acroptychia bathiei: Fischer-Piette & Bedoucha 1965: 61 , fig. 12, pl. 1, figs 9–11; Fischer-Piette et al. 1993: 47, pl. 1, figs 19–21. Type loc.: ‘près de la rivière Andranomavo (Ambongo)’ [Perrier de la Bâthie leg.], NW Madagascar’.

Morphological notes:

External features ( Fig. 25A ): Head-foot mostly greyish, irregularly mottled with darker spots and blotches; eyestalks pale, but tentacles more or less uniformly dark; forehead and snout brown; tip of snout shallowly indented in mid-line; skin texture relatively smooth.

Operculum: Corneous, oligospiral with an eccentric nucleus.

Radula ( Fig. 3 ): Formula 1+2+1+2+1; length 12 mm, with ca 140 tooth rows [ca 11.5 rows/mm]; teeth robust. Rachidian tricuspid with a rounded central cusp and two smaller lateral ones; inner and outer laterals similar, each with four cusps, of which the second is consistently the largest; marginals bicuspid, the outer cusp larger. Very similar to that of A. culminans Fischer-Piette & Bedoucha, 1965 , as described and illustrated by FisherPiette et al. (1969), except that the outer lateral is mostly tricuspid in that species.

Locality data: Namoroka: st’ns 930/97, 932/97. Antsingimavo: st’ns 04/06, 06/06, 08/06. Tsingy Beanka : st’ns 03/06, 11/06–13/06, 16/06–18/06, 01/09, 02/09, 06/09–09/09, 11/09, 01/10, 03/10, 05/10–08/10, 10/10. Tsingy de Bemaraha: st’ns 07/95, 14/95, 18/95, 09/96, 10/96, 12/96, 14/96. South bank of Tsiribihina R.: st’n 02/99LP.

Distribution: Restricted to central W Madagascar; from the Tsiribihina R. and southern Bemaraha region through Tsingy Beanka and Antsingimavo to the Namoroka area.

Habitat: Dry mixed deciduous-evergreen forest growing on limestone; living in leaflitter, under limestone rocks and in soil pockets on karst boulders; patchily common at both Tsingy Beanka and Antsingimavo. Also common throughout most of the Tsingy de Bemaraha reserve.

Remarks: A moderately sized, thick-shelled species with a single, well-developed, terminal, peristomal varix. Diameter rarely more than 24 mm. Shell essentially smooth save for fine axial pliculae on the early teleoconch whorls and fine, close-set growth-lines on later whorls. Umbilicus relatively narrow and deep. Juveniles have a much thinner shell that is frequently weakly angled at the periphery ( Fig. 2F ).

The ground colour ranges from a pale yellowish white to a deeper pinkish or orangebrown; in fresh specimens this is overlain by a fine, irregular whitish mottling, which is in turn overlain by a thin, rather glossy, corneous periostracum. However, the latter is commonly eroded in parts, after which the whitish mottling is quickly worn off and the shell becomes more uniformly coloured. A darker spiral line is frequently present just below the periphery, occasionally another just above it and sometimes a third in the middle of the base.

Family Pomatiidae Newton, 1891

Genus Tropidophora Troschel, 1847

Tropidophora chavani Fischer-Piette, 1949

Figs 4 , 9E

Tropidophora chavani: Fischer-Piette 1949: 15 , pl. 1, figs 4–6; Fischer-Piette & Bedoucha 1965: 73; FischerPiette et al. 1993: 102, pl. 5, figs 6–8. Type loc.: ‘gorges de Salapanga (Bemaraka)’ [= Bemaraha].

Locality data: Tsingy Beanka : st’ns 12/06, 14/06, 15/06, 01/09, 02/09, 06/09, 07/09, 08/09, 09/09, 01/10, 05/10, 07/10, 08/10, 09/10, 10/10. Tsingy de Bemaraha: st’ns 18/95, 04/96, 09/96, 10/96, 12/96.

Distribution: A narrow-range endemic; currently recorded only from the Bemaraha region and Tsingy Beanka .

Habitat: Dry forest growing on limestone; found in leaf-litter and between limestone boulders.

Remarks:A moderately common species in the central Tsingy Beanka , but usually present at rather low density. It is characterised by its low spire and uniformly fine spiral sculpture. Specimens with a similarly dense spiral sculpture have been collected at Andranavory in the Toliara [Tuléar] region, but these are more elevated and have a flaring white lip, which is broadly reflected in the columella region, half covering the umbilicus. They are closer to T. semidecussata (Pfeiffer, 1847) than they are to T. chavani .

Figures

Fig. 2. Acroptychia bathiei Fischer-Piette & Bedoucha, 1965: (A–C) Tsingy Beanka, st’n 18/06, max. diameter 23.7 mm, NMSA L7174; (D–F)Antsingimavo, st’n 04/06,NMSA L7091:(D) typical shell, max. diameter 23.0; (E) pale yellow specimen with a less elevated spire, max. diameter 21.7 mm; (F) juvenile specimen, max. diameter 14.9 mm.

Fig. 3. Acroptychia bathiei Fischer-Piette & Bedoucha, 1965, radula, NMSA L7039: (A) entire width of radula; (B) oblique view of left half row. Scale bars = 100 μm.

Fig. 25. Living animals from Tsingy Beanka: (A) Acroptychia bathiei Fischer-Piette & Bedoucha, 1965, st’n 13/06, shell diameter 23.2 mm, NMSA L7315; (B) Tropidophora humbug sp. n., st’n 12/06, shell diameter 28.3 mm, paratype,NMSA L7204/T2984; (C) Tropidophora secunda Fischer-Piette & Bedoucha, 1965, st’n 03/06, shell diameter approx.19.0 mm; (D) Clavator griffithsjonesi Emberton, 1999, st’n 12/06, shell height 94.8 mm, NMSA L7192; (E) Ampelita milloti Fischer-Piette,1952,st’n 07/09, shell diameter 19.2 mm, NMSA L8502; (F) Ampelita namerokoensis Fischer-Piette, 1952, st’n 12/06, shell diameter 20.3 mm, NMSA L8442; (G) Kalidos griffithshauchleri Emberton, 2002, st’n 12/06, shell diameter approx. 60 mm; (H) Kalidos maryannae sp. n., st’n 12/06, shell diameter 22.5 mm, paratype, NMSA L7193/T2944.

Fig. 4. Tropidophora chavani Fischer-Piette, 1949: Tsingy Beanka, st’n 15/06, max. diameter 27.0 mm, NMSA L7129.

Fig.9. Tropidophora sericea sp.n.and T. chavani: (A–C) T.sericea, holotype,Tsingy Beanka,max.diameter 37.3mm, height18.9 mm,AMS C.474166;(D, E) adult teleoconch sculpture of T. sericea (holotype) and T. chavani (NMSA L8447) respectively, scale bars = 2.5 mm.