Secondary Male Sex Characteristics of Hoplolaimus galeatus.

The secondary male sex characteristics of Hoplolaimus galeatus consisted of caudal alae, two independently retractable spicules and a gubernaculum with two bilobed titillae. The spicules were dimorphic, with the outer one possessing a velum. When both spicules were completely extruded, the only open orifice on the ventral surface of the posterior region was formed by the close association of these two appendages. In specimens where the inner spicule was slightly retracted, the velum almost completely surrounded the inner spicule. When the inner spicule was retracted further, the velum appeared to convolute, closing the orifice described above.