From Ancient Greek meta (μετά) "after, beside" and the Old World salticid genus Cyrba (Wikipedia--Metacyrba).
Print References
Edwards G.B. 2005b; A review of described Metacyrba, the status of Parkella, and notes on Platycryptus and Balmaceda, with comparison of the genera (Araneae: Salticidae: Marpissinae); Insecta Mundi, 19(4): 193-226 (pdf available)