Amphidromus atricallosus perakensis

Amphidromus atricallosus perakensis (Fulton, 1901)

Languages: English


Diagnostic Description

“At first sight one could easily take this species to be one of the numerous varieties of A. perversus, but on holding the shell obliquely, the very characteristic columellar projection becomes conspicuous. This plate appears, from an exterior view, to be thick, but on breaking away the wall of the shell, it is seen to be quite thin. All the numerous specimens collected are quite constant in the possession of this peculiarity, although it is more prominent in some than in others.” (Fulton, 1901)

“Both a dextral and sinistral form, bright yellow in colour, with a white zone below the suture, and no brown striping. One specimen, dextral, measures 62 millim. I have followed Pilsbry (Man. Conch., vol. xiii, p. 160) as I gather that the name perversus, which I should otherwise have used for this shell, is to be restricted to forms found in Celebes, Java, and Borneo.” (Sykes, 1902)

Diagnosis - “Shell usually yellow with a white narrow subsutural band, but white shells are known to ocuur. Parietal callus white or transparent, lacking axial bands (varices) on the whorls that are present in the other three subspecies.” (Lok & Tan, 2008)

Author(s): Marzuki, Mohammad Effendi
Rights holder(s): Fulton, 1901; Sykes, 1902; Lok & Tan, 2008


Fulton (1901) original descriptions on Amphidromus perakensis – “Shell dextral or sinistral, solid, general form as figured, imperforate, polished, yellow with a narrow conspicuous band at the suture; whorls 7½, slightly convex, with weak oblique striae or lines of growth; columella bearing a thin and somewhat flat projecting plat, situated interiorly at about a third of a volution from the exterior; peristome white, thick, expanded and slightly reflected, margins connected by a transparent raised callus, columellar portion triangularly dilated above, somewhat angular below: aperture sub-ovate, whitish within.”

Lok & Tan (2008) descriptions on Amphiromus atricollosus perakensis - “Enantiomorphic with dextral and sinistral shells, that are high conical with a pointed but not sharp apex. The shell is also polished light yellow sometimes mixed with patches of white although living specimens appear light mint green owing to the colour of the animal’s body darkening the shell. The shell also has shallow sutures and a white subsutural zone lacking darkened callus. The aperture is oblique with a thick, reflected lip. The juveniles are also differentiated from the adults in that they have more angular shells with a sharp and thin lip without thickening.”

Author(s): Marzuki, Mohammad Effendi
Rights holder(s): Fulton, 1901; Lok & Tan, 2008


Shell height – 48-50 mm; Shell width – 26-27 mm.

Author(s): Marzuki, Mohammad Effendi
Rights holder(s): Fulton, 1901

Ecology and Distribution


Type locality – “Perak” Leg. Grubaeuer (Fulton, 1901)

Other localities – Amphidromus atricallosus Gould, 1844 “Mergui forest and King island” (Martens, 1889); “Kelantan, Malay Peninsula” leg. J. Waterstradt (Sykes, 1902); “Singapore; Dairy Farm, Bukit Timah Nature Reserve” leg. S. Y. Chan/Apr. 18,

Author(s): Marzuki, Mohammad Effendi
Rights holder(s): Fulton, 1901; Martens, 1889; Sykes, 1902; Lok & Tan, 2008


Habitat – “They are arboreal snails that spend much of their time in scrubs or trees… can sometimes be seen grazing on concrete structures.” (Lok & Tan, 2008)

Author(s): Marzuki, Mohammad Effendi
Rights holder(s): Lok & Tan, 2008

Trophic Strategy

Feeding habit - “…believe that these snails feed on microscopic flora such as fungal mats, lichens, or algal epiphylls.” (Lok & Tan, 2008)

Author(s): Marzuki, Mohammad Effendi
Rights holder(s): Lok & Tan, 2008


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