Pseudaphanostoma divae Marcus, 1952

(Figs. 19)

Material. Living specimens in squeeze preparation; whole mounts for fluorescence imaging of musculature.

Locality. Praia São Francisco, São Sebastião, São Paulo, Brazil, from intertidal coarse-grained sand (23°45’45.1”S, 45°24’27.1”W).

Description. Living specimens ~ 1.3 mm long and 200 m wide (Fig. 19A). Conspicuous gold rhabdoid glands in rows visible by transmitted light. Mouth opening on ventral surface, middle of body.

Female gonopore and accessory organs absent. Male gonopore at posterior end; opens to muscular penis invaginated into elongate, muscular seminal vesicle (Fig. 19B).

Remarks. The male copulatory organ was difficult to see in squeeze preparations of live material. Marcus (1952) reported that the gonopore of P. d i v a e was positioned terminally or subterminally; however, at least one of our specimens had a supraterminal male gonopore (Fig. 19B). The penis musculature of this species is consistent with that found for other species in the family Isodiametridae (see Hooge & Tyler 2005).