* Government captures second drug lord within weeks
* Arrest is another blow to Beltran Leyva cartel
By Cyntia Barrera Diaz
MEXICO CITY, Sept 13 (Reuters) - The arrest this weekend of a Mexican drug lord dealt another blow to one of the country's top cartels, but President Felipe Calderon's government still faces challenges as it seeks to rein in a thriving drug trade.
In a bloodless arrest on Sunday, Mexican marines captured Sergio Villarreal, a muscular former policeman whose 6.6-foot (2 meter) stature helped earn him the nickname of 'El Grande,' or 'The Big One,' the second leading figure from the powerful Beltran Leyva cartel to be captured within weeks.
The arrest marked a fresh victory for Calderon's war on drugs following the arrest late last month of Edgar "La Barbie" Valdez, a fellow capo vying for leadership of the same cartel after authorities killed its former leader in December.
"The cartel is greatly weakened ... There will be a reshuffling (of leaders) but the weakening will be substantial," marines spokesman Jose Luis Vergara said in a press conference on Monday.
An unshaven Villarreal, wearing a black tee shirt with the logo of a Texas basketball team, towered over masked soldiers at his elbows as officials presented him to the public.
Blamed for fueling a gruesome turf war within the Beltran Leyva cartel, Villarreal's face was stony as he faced reporters just days before his 41st birthday.
Alberto Islas, a security analyst with Risk Evaluation, said Villarreal trafficked up to 10 tonnes of cocaine a month into the United States, a large part of a booming drug trade believed to bring Mexican cartels up to $40 billion a year.
Yet his capture could intensify the power struggles that have gripped the Beltran Leyva cartel following former boss Arturo Beltran Leyva's death late last year, and possibly boost feuds between cartels seeking control of smuggling routes.
Less clear is what the impact of recent arrests will be on overall violence in Mexico, where more than 28,000 people have died since Calderon launched his crackdown on cartels in 2006.
Journalist and drug expert Raymundo Riva Palacio told local radio that El Grande was believed to be behind dozens of recent gruesome murders in the central state of Morelos as Villarreal challenged Valdez for leadership of the cartel.
According to intelligence reports, Villarreal's other nicknames included 'King Kong' and 'Come Ninos,' or 'Child Eater.' (Editing by Missy Ryan and Jerry Norton)
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