Madagasikara johnsoni
Species of gastropod
From Wikipedia, the free encyclopedia
Madagasikara johnsoni is a species of tropical freshwater snail with a gill and an operculum, an aquatic gastropod mollusc in the family Pachychilidae.[3]
| Madagasikara johnsoni | |
|---|---|
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| Apertural view of a shell of Madagasikara johnsoni | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| Subclass: | Caenogastropoda |
| Order: | incertae sedis |
| Family: | Pachychilidae |
| Genus: | Madagasikara |
| Species: | M. johnsoni |
| Binomial name | |
| Madagasikara johnsoni (E. A. Smith, 1882)[2] | |
| Synonyms[3] | |
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Distribution
This species is endemic to Madagascar.[3] The only precisely known locality is in Ankara Sontsitra National Park, West Madagaskar.[3]
The type locality was given as "River Kamony, in the north-west of the island",[2] but the thereabouts of this locality has not been exactly determined.[3] The most detailed version of the type locality is that of the Kamoro River drainage in Mahajanga Province, north-west Madagascar.[3]
Description
Madagasikara johnsoni was originally discovered and described (under the name Melanatria johnsoni) by Edgar Albert Smith in 1882.[2]
The shell is large, elongate-pyramidal, turreted, thick, covered with an olive epidermis.[2] It is closely lineated or strigate with longitudinal lines of a darker tint.[2] The shell has nine whorls.[2][3] Whorls are very slightly convex beneath, strongly spirally ribbed and grooved.[2] The ribs are six in number on the upper whorls and rounded; the two above are much more slender than the four beneath; the uppermost borders the suture; the next lies in the concavity at the top of the whorls; and the rest surround the slight convexity, and are three times as broad as the sulci separating them.[2] All the whorls, with the exception of the last four, are coronated at the slight angle below the excavation with very short, hollow, oblique spinules.[2] Some of the spiral grooves exhibit rows of fine granules.[2] The last whorl descends somewhat, giving the shell a slightly distorted appearance.[2] It is girded with about twelve transverse costae, a few at the base being smaller than five principal ones around the middle.[2]
The aperture is bluish within, faintly stained with olive-brown near the margins.[2] The peristome widely and deeply sinuated on the outer lip in the concavity of the whorl, arcuate and prominent in the middle, then shallowly sinuated again.[2] Columellar margin is thickened, free, arcuate, reflexed, ending in a distinct basal sinus.[2]
The width of the shell is 24–28.9 mm.[2][3] The height of the shell is 69.9-77.7 mm.[3] The width of the aperture is 14.0-14.2 mm.[3] The height of the aperture is 20.5-21.0 mm.[3]
There is not known description of operculum.[3] There is also not known anatomy of this species.[3] Reproduction strategy is also unknown.[3]