page_title: Amphidromus perversus
section_title: Shell description
hierarchical_section_title: Amphidromus perversus / Shell description
caption_attribution_description: English: Photo of apertural view of the shell of lectotype of Amphidromus perversus perversus form niveus. Locality: Pare-Pare, Celebes. Taken in: Naturhistorisches Museum, Basel.
context_page_description: Amphidromus perversus is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae.
  Amphidromus perversus is the type species of the genus Amphidromus, by the subsequent designation of Eduard von Martens.
context_section_description: Amphidromus perversus are amphidromine (left-handed and right-handed snails occur in the population).
  In Amphidromus perversus and most other thick-shelled Amphidromus species, the lip is internally thickened, forms a "roll" in its expansion, and has a very heavy parietal callus.
  The shell is solid, polished, amphidromine, moderately large (45–55 mm) high, usually with a dark varix. Lip and callus white; ground color white, orange, yellow, or yellowish-green. Many specimens with interrupted or continuous radial brownish streaks covering part or all of the whorls on the lower spire and body whorl.
  Amphidromus perversus undoubtedly offers the greatest array of discretely variable color combinations of any species of Amphidromus.
  Color variation of Amphidromus perversus perversus include 12 forms:
  Amphidromus perversus perversus f. aurea Dillwyn, 1817 (not Martyn, 1784), is usable for the orange-colored (instead of yellow) monochrome shells found on Java and Celebes. Apparently an individual variation.
  Amphidromus perversus perversus f. aureus Martyn, 1784 — It still have not been reported from a precise locality. It was based on three shells collected by Sir Joseph Banks, supposedly on Pulau Panaitan. The only Amphidromus found there, Amphidromus banksi Butot, is quite different and the actual locahty of aureus is still unknown. The shells have a wide, white zone below the suture as in the Amphidromus atricallosus complex and the lower parts of the whorls are yellow, with or without narrow, wavy, reddish-brown flammulations. The original specimens in the Natural History Museum appear to be a form of Amphidromus perversus, but the locality remains a mystery. Note: Martyn's work was invalidated by action of the International Commission on Zoological Nomenclature, varietal names are not accorded legal status and the use of aureus is as a convenient term of reference.
  Amphidromus perversus perversus f. borneensis Pilsbry, 1900, is based on a stout variant of the interruptus pattern, whitish in background color, and rather similar to the Javanese subspecies, emaciatus. It was described from South Borneo in the Bandjermassin District (Chicago Natural History Museum 63377), but there are specimens in the Naturalis, Leiden from East Borneo. The flammulations above the periphery are reduced in number. Possibly this may prove to be a subspecies, but not enough data are available.
  Amphidromus perversus perversus f. infrapictus von Martens, 1867, was considered by Pilsbry (1900) to be identical with interruptus Müller, 1774. At best it might be considered a slightly different stage in an almost continuous series of variations.
  Amphidromus perversus perversus f. infraviridis von Martens, 1867, probably is a derivative of the Celebesian infrapictus. Instead of flammulations and a basal purplish zone it has a pale green or greenish-yellow base which is only slightly darker than the greenish-yellow or citron-colored spire. It is most similar to typical perversus but differs in the darker basal portion.
  Amphidromus perversus perversus f. interruptus Müller, 1774, has a purplish or brownish zone on the base, a yellow or whitish patch near the columella, and brownish flammulations that are somewhat interrupted on the periphery and do not reach the suture above.
  Amphidromus perversus perversus f. mitra von Martens, 1867, is an unfigured variety from Bali and seems to be intermediate between interruptus and sultanus.
  Amphidromus perversus perversus f. niveus P. & F. Sarasin, 1899 is snow-white with a black varix and black mark behind the peristome. It is an "albino" perversus which is common in the Celebes and sporadically seen from Java and Borneo.
  Amphidromus perversus perversus f. obesus von Martens, 1867, is an unfigured variety which probably can be equated with squat individuals of the typical perversus pattern.
  Amphidromus perversus perversus f. perversus Linnaeus, 1758, is a solid yellow shell with black varix and narrow black band behind the peristome. It is known from the whole range of the species.
  Amphidromus perversus perversus f.
caption: Amphidromus perversus perversus f. niveus
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