Figure 5. Cryptogeobiidae. Matching hyaline fasciolate apophyses (FAp), ‘alpha shark’s fin’ of trochanter IV and ‘horse’s head’ of coxa IV. A, Pseudopachylus longipes, male (MNRJ 17649), ventral view of stigmatic area and base of leg IV. B, Tibangara nephelina, male (MNRJ 1964). The same region as preceding illustration, showing ‘bundle’ structure of both FAp. Scale bars = 1 mm (A), 0.1 mm (B).[1]
This is a term introduced by Kury (2014)[1] to describe the structure of apophyses of coxa and trochanter IV of the males of many species of Cryptogeobiidae. It was originally abbreviated as FAp.
According to original definition, they are "apophyses of basal segments of male leg IV, which are not hardened conical processes, but made of many lesser sclerotized units that give an impression of a bundle of transparent fibres."