Larvae of all three instars of the diving-beetle species Notaticus fasciatus Zimmermann (Coleoptera: Dytiscidae) are described and illustrated in detail, with particular emphasis on chaetotaxy and morphometry, and the phylogenetic relationships of the genus Notaticus Zimmermann within Dytiscidae are investigated based on a cladistic analysis of 66 larval characters. Including Notaticus in its own subfamily, as is sometimes done, would result in Dytiscinae paraphyletic with respect to Aubehydrinae. Notaticus is found to be distinctive within Dytiscinae, being characterized by several apomorphies, including pore FRf and occipital suture absent, seta AN1 inserted distally on antennomere 3, seta MX8 subapical and pore MXh submedial on galea, pore LAc basal on labial palpomere 2, and abdominal segment VII completely sclerotized ventrally in instar I. Inclusion of Notaticus in a distinct tribe (Aubehydrini) seems warranted. A subordinate position of Notaticus within Dytiscinae is proposed, with Aubehydrini being part of a clade along with Hydaticini, Aciliini, and Eretini. Support is presented for a clade Aubehydrini Aciliini Eretini based on the presence in these taxa of a gibbous larva, short rounded spinulae on antennomere one in instar I, and a strongly developed and spiniform galea with the seta MX9 inserted subapically on it. It is postulated that Aubehydrini is sister to the clade Aciliini Eretini. A key separating larvae of the tribes of Dytiscinae is presented.