Plus the spider-eye goblins* and the narleth from CC1. And of course, Aranea and Ettercap. If you picture in crabmen, stingers, and sandmaskers/scorpionfolks, the arachnidmen niche is really crowded. Bah, at least, we don't have yet crablicemen.
A little comment, though: "
A chagmat can either be a fighter or a cleric, and its class is determined at birth." -- This is
so AD&D2...
(* IMC, they are known as Aragais, and they have been modified to get a burrow speed (20 ft.), 8 legs, and improved trip, their full attack routine is bite/claw/claw/claw/claw/trip.