First tarsal segment of the prothoracic leg. Proximally, it articulates with the tibia and distally with the second tarsal segment. Its surface is covered with eight longitudinal rows of bristles and with transverse rows of bristles (TR) in the anterior compartment, between proximo-distal rows 7 and 8. There is sexual dimorphism in the number of TRs (transverse row bristles, TR). In males, 2 TRs are replaced by the sex comb and one central bristle. [ ]