Cardiocrinum, including the magenta flowered form of C. cordatum cordatum.
As well as the information sources listed in the 'genus' section, the links below have useful information and pictures of a selection of species.
The book on the genus most often recommended is "The Genus Arisaema" by G & L Gusman. The problem is that this is out of print and second hand copies command a rather high price. The 1st. Edition, 2003, ISBN 390414491X, is available at Amazon for ~£140 to £400 but is advertised at €39.00 from Koeltz Botanical Books. The expanded, 2nd. edition, 2006, ISBN 0881928399, can be bought on Amazon for ~£1200.
Another worthy, (and also out of print), book which covers just the Himalayan species is "Himalayan Cobra-Lilies (Arisaema): Their botany and culture" by Udai C. Pradhan. I bought a copy of the 1st. edition, 1990, with B&W illustrations, ISBN 8185423008, for £20 at an eBay auction. The 2nd. edition, 1997, with colour photos, ISBN 8185423040, can be bought on Amazon from £250 to £840.