The Mexican retained his title with a unanimous points decision over the 34-year-old McCullough, with the judges offering wide margins of 118-109, 118-110 and 116-11. McCullough felt the scoring was "way off" - as did many at ringside - after 12 hard rounds in which the initiative often fluctuated.
Indeed, McCullough's pressure seemed to give him the edge at the half- way mark before Larios gradually took the upper hand but every round was contested with great intensity.
"I'm not even thinking about retirement. I want to go home to Vegas and regroup and plan where I go from here," said McCullough, who left Larios with a nasty cut over his eye. "I'm very disappointed with the result but I showed that I can still take on the very best. I forced the fight the whole way and I got through with some great body punches.
He added: "I thought I won the early stages and then from rounds seven to 10 he probably got on top but then I came strong again in the 10th. At the end I thought I may have got the decision. It was certainly a lot closer than the judges had it.
"I could have done with more fights before this but I don't make excuses. I gave it everything."
Many felt that after his severe beating by the World Boxing Organisation featherweight champion Scott Harrison two years ago, the time was right for the Belfast man to retire. But he added: "I think I showed in this fight that the Harrison fight was a one-off. I wasn't right going into the fight and I never got going. I showed in this fight that I am back to where I was. I think I proved a point."
Such was the intensity of the duel that Larios may have to postpone his scheduled meeting with the WBO champion Joan Guzman set for 9 April. Larios was finding it hard to handle the challenger and McCullough's volume of punches had him in front at the midway point.
But gradually McCullough seemed to tire and the final third belonged, crucially, to the champion. The Ulsterman was in serious trouble at the end of the 10th and while lesser men would have gone down he remained on his feet despite the heavy bombardment.
At the final bell the judges did not do McCullough justice but once again he proved his ring warrior's heart with a gutsy display.Reuse content