The first instar of Laccornellus lugubris (Aubé) is described. A parsimony analysis of selected taxa of the subfamily Hydroporinae based on 48 informative larval characters was conducted using the program PAUP*. The 100 most parsimonious trees support a placement of Laccornellus Roughley & Wolfe outside the tribe Hydroporini as part of a clade made up of Hydrovatus Motschulsky Canthyporus Zimmermann, which is supported by the absence of the primary seta UR8 and of the primary seta LA2, and the spine-like condition of the primary seta AB10. Larvae of Laccornellus evolved one unique character state within the Hydroporinae, which is the presence of the primary seta AB15 on ventral surface of last abdominal segment.