Key 2: Key to Ilanga species of Indo-Pacific area studied in this work
1. subsutural axial pleats visible on second or third whorl........................................................ 2 - no obvious subsutural axial pleats on whorls.............................................................. 13 2 (1). umbilical rim rounded to weakly subangulate............................................................... 3 - umbilical rim angulate................................................................................. 6 3 (2). no axial threads inside umbilicus........................................................................ 4 - axial threads inside umbilicus........................................................................... 5
4 (3). conical shape with nearly flat whorls................................................... I. cosmia
- conical to slightly cyrtoconoidal shape, convex whorls.................................. I. corrineae
5 (3) rather depressed spire, 4 Pi, very large umbilicus........................................... I. comes - rather elevated spire, 5 Pi, moderately large umbilicus.................................. I. dongshaensis
6 (2). always axial threads inside the umbilicus.................................................................. 7
- no axial threads always present inside the umbilicus.......................................................... 9
7 (6). ± 3 spiral cords around umbilicus, central base area reticulate............................... I. oxeia
- usually one single spiral cord around the umbilicus.......................................................... 8
8 (7). rounded periphery without spiral cords.............................................. I. eurystoma
- subangulate periphery, faint spiral cords on periphery.................................... I. harrytaylori
9 (6). depressed, lenticular................................................................................. 10
- at most moderately depressed........................................................................... 11
10 (9). strongly depressed, spiral cords around the umbilicus, up to 19 mm ............................. I. gotoi
- a single spiral cord around the umbilicus.......................................... I. euryomphalos
11 (9). rather elevated spire............................................................ I. navakaensis
- moderately depressed spire only........................................................................ 12
12 (11).5 Pi....................................................................... I. stephanophora
- 4 Pi......................................................................... I.polygramma
13 (1). umbilical rim only weakly subangulate.................................................. I. fulgens
- umbilical rim angulate or at least subangulate.............................................................. 14