Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Situational Awareness
Deviation - Speed All Types; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew Requested ATC Assistance / Clarification
Chart Or Publication; Procedure; Human Factors; Airspace Structure
I was the Captain (Pilot Monitoring) during an arrival to SNA. We were flying the OHSEA2 arrival. We had descended to 5;000 feet to meet a crossing restriction. We were at 250 knots and I thought it was a good time to slow; since we had a level portion of the arrival. At this time; ATC radioed the instruction; 'Slow to 200 knots; you are below the Class Bravo.' We complied immediately; but it seems we should have already been at 200 knots. There is no depiction of the Class B on the arrival chart; nor is there a speed restriction depicted; as there were further up on the chart. We were over open water and on an IFR arrival designed for Turbojet aircraft. My personal solution going forward was to mark my chart with the 200 knot restriction and make sure I program it in the FMS that way as well as to pay more attention to other arrivals when operating at airports in the vicinity of [the] larger; Class B airport. While it looks like the waypoint LAXBB may be named to indicate that airspace; it is not noted as such on the chart. Furthermore; there is no published speed restriction at LAXBB; and I believe this would be a good charted solution to alleviate the threat for all pilots.
Cleared to descend via the OHSEA 2 RNAV STAR landing 20R into SNA. After leveling at 5000 feet in between LAXBB and KLEVR ATC instructed us to 'maintain 200 knots beneath the Bravo'.  Our speed at the time was 250 knots. The Class Bravo is not depicted on the OHSEA 2.  Depicting the Class Bravo or mandating a 200 knot speed limit at LAXBB would be helpful for situational awareness.
EMB-175 flight crew reported exceeding 200 kts below LAX Class B airspace while flying the OHSEA2 RNAV arrival into SNA.