Ampelita andriamamonjyi sp. n.

Fig. 12

Etymology: Named for Aldus Andriamamonjy, Executive Director of Biodiversity Conservation Madagascar that manages and protects the forests of the Tsingy Beanka.

Diagnosis: Shell lenticular, periphery rounded; aperture strongly descendant; umbilical width moderate; whitish to fawn, characteristically patterned with 3 or 4 dark brown spiral bands, 1 or 2 above periphery, 2 below; sculpture of close-set, incised spiral striae; apertural rim reflected.

Description:

Shell: Medium sized, lenticular (H:D= 0.489 –0.586); whorls slightly flattened, periphery rounded; suture weakly indented, final part of last adult whorl descending conspicuously prior to aperture; umbilicus of moderate width, steep-sided and distinctly narrower internally. Protoconch of ca 1½–2¾ whorls, superficially etched in most specimens but some individuals with evidence of fine, close-set spiral threads on last whorl; junction with teleoconch usually ill-defined. Teleoconch of a further 2¼ whorls; sculptured by numerous, close-set, incised spiral striae; striae crossed by frequent fine, irregular growth-lines rendering the former wavy; basal sculpture similar, but weakening at umbilical rim and evanescing within. Aperture elongate-ovate, strongly oblique to vertical axis of shell; peristome incomplete, interrupted in parietal region, elsewhere its rim reflected, forming a flaring lip.

Shell somewhat glossy; embryonic whorls buffish brown, slightly darker below suture; first teleoconch whorl with two dark brown spiral bands, lower one broad, situated just above abapical suture, the other narrower, lying a short distance below adapical suture; interval between upper brown band and suture almost white; upper brown band usually fading and disappearing with growth (sometimes within first half whorl), but persisting throughout in some individuals; ground colour becoming paler with growth, a rather uneven dirty white on last adult whorl; base with two further dark brown spiral bands, one just below periphery (emerging close to insertion of outer lip), the other midway between this and umbilical rim; ground colour between supra- and sub-peripheral brown lines paler, almost white; pale subsutural zone persisting throughout.Aperture lip white, colour bands clearly visible internally.

Dimensions: Holotype (largest specimen), max. diameter 29.3 mm, height 15.1mm.

Holotype: MADAGASCAR: Central W Madagascar, ca 60 km E of Maintirano, southern part of Tsingy Beanka, S side of Tana–Maintirano road, in tall moist forest growing on limestone on south-facing slopes, above N bank of Kimanambolo River, 18.06178°S 44.52494°E, ca 330 m, iv.2010, R. Randalana, st’n R02/10 (AMS C.474164).

Paratypes: Same data as holotype (TMAM T162, 1 adult specimen); st’n R03/98 (NMSA L8441 /T2657, 2 adult specimens); st’n 04/06 (AMS C.469582, 1 adult specimen); st’n 16/06 (NMSA L7128 /T2656, 1 subadult specimen); st’n R04/09 (MNHN IM-2010-20070, 1 adult specimen); st’n R01/10 (AMS C.469581, 3 adult specimens).

Additional locality data: Tsingy Beanka: st’ns 13/06, 16/06, 02/09, 08/09 (subfossil), R04/09, R01/10.

Distribution: Fresh material has been found only in the Tsingy Beanka.A single subfossil shell is known from Antsingimavo, but the species is now perhaps extinct there. Not recorded from the Tsingy de Bemaraha.

Habitat: Fresh dead shells found most commonly in and amongst limestone rocks, predominantly in the taller moister forests of the southern part of Tsingy Beanka. Not yet found alive.

Remarks: Compared to other spirally banded Ampelita species, the banding pattern of A. andriamamonjyi is distinctive. A. akoratsara Emberton, 1999 (from Marojejy in far north-eastern Madagascar) has a somewhat similar pattern of dark brown spiral lines with whitish subsutural and peripheral bands, but it has a sharply keeled body whorl and lacks the mid-basal brown spiral band of A. andriamamonjyi. Unlikely to be confused with any other known Ampelita species.