The creature is most famously known as the jba fofi, the name that Baka tribe speople in the Congo have called the giant arachnids that reportedly reside by their dwellings.

这个句子中的二个that从句都是定语从句。第一个that从句修饰the name, that在从句中作宾语补足语。该从句为SVOC句型，call +名词宾语+名词宾补。that在从句中作了宾补，移至句首引导从句，故从句动词call之后只有宾语，没有宾补了。the name被限制性定语从句修饰，构成名词词组，作the jba fofi的同位语。

第二个that从句修饰名词the giant arachnids， that在从句中作主语。