I don't know which phone book you are using but of the over 100 PUSKAR I found plenty of Muslimani names and some that may be Croatian or Muslim.Here are PUSKAR found in US phone books with original "Bosnian" names:
Switchboard is my favorite way to search US Phone books.
Also those PUSKAR you found in the phone book who have are second generation in the US it is hard to tell where they originated because they have American names now and this may even be the case with immigrants who have possibly changed their names. Also many listings only have the first initial, so who knows what their given name is!
Genealogically speaking puškar is an occupational surname meaning rifle maker.
Ellis Island shows 285 PUSKAR arrivals, of which 27 declared their race as Croatian, 0 Bosnian, 6 Servian, 103 SlovakIt appears that many of those early PUSKAR immigrants came from Topusko and Perna both in Croatia.These places are Kordun or Sisak area.