Perisserosa guttata - its subspecies and forms

A quick "how can I tell"

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There have been people who wonder about the differences between the various taxa assigned to
the beautiful and variable P. guttata (formerly Erosaria)

Here is a short comparison:

guttata guttata	guttata guttata var. bicallosa	guttata surinensis	guttata surinensis var. bengalensis	guttata azumai
dorsum with large and small lacunae		dorsum with small lacunae		dorsum with large but mostly blurred lacunae
small blotch on labrum		large blotch on labrum		mostly no blotch on labrum
Philippines		India to Thailand		China Sea
stripes on labrum rather corarse, moving slightly towards dorsum	stripes on labrum rather coarse interrupted by white callus	stripes on labrum moving far onto dorsum	stripes on labrum finer, moving towards dorsum, but not quite that much	stripes on labrum very coarse and fewer, not moving onto dorsum, no white callus
columellar side hardly callused	columellar side stronly callused, interrupting lines	columellar side slightly callused	columellar side very callused, but lines go across	columellar side not callused at all
Rather large, inflated and heavy	smaller, slightly depressed, very heavy	smaller, depressed, heavy	smaller, very heavy and very depressed	larger, light weight and inflated
basal ground color white		basal ground color yellowish		basal ground color white

guttata guttata: note the two distinct basal blotches, the absence of a labral blotch,
the large and small lacunae and the inflated shell

guttata guttata, variation bicallosa: it is smaller and depressed,
the sides are heavily callused with a white accumulation

guttata surinensis: the basal blotches are larger, the lines finer and moving up further.
Note the smaller and more numerous dorsal lacunae

guttata surinensis var. bengalensis: in this insignificant variation, the shell is more callused and broad.

guttata azumai: in the subspecies (of geographic variation) from the China Sea ,
the shell is lighter in weight, the stripes are short and coarse, and the blotch on labral side
is mostly (but not necessarily) absent. The dorsal lacunae are often small as in the one shown here,
but may be rather large, but they are mostly indistinct.

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first uploaded June 2004