Composite map of chromosome arm IIL of Simulium bergi (female larva), representing the Simulium subgeneric standard. Breakpoints of sex-linked inversions are indicated with brackets or arrows. Ordering the two independent sets of chromosome fragments indicated by the letters “a” through “h” will produce the inverted sequence for IIL-39,40 and IIL-49,50. CII = centromere of chromosome II, hc = insertion point for heterochromatic block, Pb = parabalbiani, 2ºNO = location of secondary nucleolar organizer, * = insertion point for 7 additional bands (only when IIL-41 is present).