Carapace more or less hexagonal and heavily setosed, conspicuously convex with regions defined by deep grooves. Frontal region narrow, deflected posteriorly and distinctly bilobed with medial fissure. Antero-lateral margin strongly convex, without teeth but with tuberculated border. Flagellum of antennal can be pushed into the orbit via a small gap. Chelipeds strong and nearly equal in size and crest absent on dorsal margin of propodus. Walking legs round in section and without a crest on the dorsal margin of the merus, carpus and propodus. In the male, abdominal somites 3-5 are fused and not moveable.
Vernacular name: Indian Paddington bear crab.
This is an exceedingly rare crab that the famous Indian carcinologist Professor Sankarankutty first described in 1966 from a single female specimen. It was collected from Devipatnam, Palk Bay, Gulf of Mannar, India. The present crab collected from Ban Tha Yang (Kog Tap) Kapoa District, Ranong was captured using a tangle net on a muddy bottom. It is only the second time that Zalasius indicus has ever been recorded and Thailand represents a considerable extension to its known range. Zalasius indicus is separated from the three other know species (Z. dromiaeformis, Z. horii and Z. sakaii) in the genus by the conspicuous absence of course granulation on the carapace.