Museum specimens were examined from ichthyological collections at the Academy of Natural Sciences of Philadelphia (ANSP); Laboratório de Biologia de Peixes, Departamento de Morfologia, Universidade Estadual Paulista, Campus de Botucatu (LBP); and Museu de Zoologia da Universidade de São Paulo (MZUSP). Descriptions of spermatic characteristics are based on analyses at the ultrastructural level of testis from adult INCB024360 males of Anadoras weddellii (LBP 672), Amblydoras sp.

(ANSP 167626), Wertheimeria maculata (MZUSP 93658), Franciscodoras marmoratus (MZUSP 84224), Kalyptodoras bahiensis (MZUSP 100737), Acanthodoras cataphractus (MZUSP 6831), Pterodoras granulosus (LBP 4322), Oxydoras kneri (LBP 4323), Rhinodoras

dorbignyi (LBP 4326) and Trachydoras paraguayensis (LBP 5627). Live specimens were anesthetized with 0.1% benzocaine and euthanized (according to institutional protocols and approval) for removal of the testis. Gonad fragments from freshly sacrificed C59 wnt datasheet fish were fixed overnight in 2% glutaraldehyde and 4% paraformaldehyde in 0.1 M Sorensen phosphate buffer, pH 7.4. The material was post-fixed in the dark for 2 h in 1% osmium tetroxide in the same buffer, stained in block with aqueous solution of 5% uranyl acetate for 2 h, dehydrated in acetone, embedded in araldite, and sectioned and stained with a saturated solution of uranyl acetate Adenosine in 50% ethanol and lead citrate. Electron micrographs were obtained using a Phillips-CM 100 transmission electron microscope. Dead” specimens from ichthyological collections (i.e., previously fixed in 10% formalin and conserved in 70% ethanol) were dissected and the removed testis gradually

rehydrated in a decreasing ethanol concentration (60%, 50%, 40% … distilled water). Once rehydrated the material was re-fixed and prepared for observation as described for the live specimens. Instances when the condition of the testis did not permit complete or accurate observations (e.g., previously fixed museum specimens) are noted as “not available” (NA). Various features of spermatogenesis, spermiogenesis and spermatozoa are summarized for the doradids analyzed herein and compared to other catfishes in Table 1. In A. weddellii spermatogenesis is semi-cystic. In this kind of spermatogenesis, although spermatogonia proliferation and meiotic divisions of the spermatocytes occur inside the spermatocysts ( Fig. 1A), spermatid differentiation is extra-cystic and occurs outside the cysts in the luminal compartment of the testis ( Fig. 1B).