Commenting on the find , snake expert Robert Henderson from the Museum of Natural History ,  said: “Worldwide new species of frogs are being discovered and described quite regularity.

请问老师，这个句子里said前面为什么要加逗号? 去掉可以吗？不明白这个逗号在这里的用法，或者说，这个句子成分的顺序还可以写成什么样，谢谢老师