The Notograptidae contains one genus, Notograptus Günther, and five nominal species from northern Australia and southern New Guinea. Morphological evidence places Notograptus among acanthoclinine plesiopids (continuous free margin of lower lip; head naked; dorsal and anal fins with many spines and few segmented rays; no extensor proprius; reduced number of caudal-fin rays) and supports a sister relationship with Acanthoplesiops (symphyseal flap on lower lip; reduced hypural 5; reduced hypurapophysis). This hypothesis resolves the relationships within Acanthoplesiops, clarifying the polarity of autogenous middle radials of dorsal- and anal-fin pterygiophores. The proposed relationships among acanthoclinines are: Acanthoclinus (Belonepterygion (Beliops (Notograptus (Acanthoplesiops hiatti (A. indicus (A. psilogaster (A. echinatus))))))). The distribution of Notograptus compliments that of its proposed sister clade in that Acanthoplesiops is unknown from northern Australia or southern New Guinea. There are repeated geographical patterns among several groups suggesting that Australia is a basal area to a broader Indo-Pacific region. Similarity between the Congrogadinae (Pseudochromidae) and Notograptus has long been noted, both having a loosely connected suspensorium and elongate body which were mistakenly considered indicators of relationship; we add reduced branchial arches, straight, tube-like gut and highly expandable anus. We examine these similarities as an indication of a shared specialized feeding habit. Notograptus is an alpheid shrimp predator, able to swallow its large prey whole. Most species of congrogadines eat whole, large crustaceans. This is probably an example of convergent adaptation to a particular selective regime. © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society, 2004, 141, 179–205.