Description of a new miniature and paedomorphic gonorynchiform ( <scp>Kneriidae</scp> : <i>Grasseichthys</i> ) from the <scp>Cuvette Centrale, Democratic Republic</scp> of the <scp>Congo</scp>

Grasseichthys zamba sp. nov., a diminutive freshwater gonorynichiform, is described from densely shaded forest streams near Lake Tumba in the Democratic Republic of Congo. Osteologically it is readily distinguished from its single Gabonese congener, Grasseichthys gabonensis, by higher vertebral counts, a reduced number of procurrent rays and fusion of hypurals of the caudal-fin skeleton. Additionally the new species can be morphometrically distinguished from G. gabonensis by numerous features of body proportions and fin lengths. Discovery of G. zamba raises the number of known miniaturized gonorynchiforms to four; however, due to their extremely small size and larval-like appearance, paedomorphic species are inconspicuous and often overlooked or misidentified as larval fishes during ichthyological surveys and in museum collections. Our study suggests that intensified, targeted sampling in the vast peatland habitats of the Congo basin presents high prospects for additional discoveries, and accurate biodiversity assessments of the diversity and distribution of Africa's miniaturized fishes.