Head of Bolbochromus spp. photographed by scanning electron microscope 19 B. (Metabolbochromus) catenatus, male 20 B. (Metabolbochromus) catenatus, female 21 B. (Bolbochromus) jengi, male 22 B. (B.) luzonensis sp. n., male 23 B. (B.) mindanaicus, female 24 B. (B.) setosifrons sp. n., holotype male. Scale bar: 1 mm