Apis nulensis Tingek, Koeniger and Koeniger, 1996 and its genetic relationship with sympatric species inferred from DNA sequences M.C. Arias, S. Tingek, A. Kelitu and W.S. Sheppard Apidologie, 27 5 (1996) 415-422 DOI: 10.1051/apido:19960509