Dromiacea

Dromiacea is a group of crabs, ranked as a section. It contains 240 extant and nearly 300 extinct species.^[1] Dromiacea is the most basal grouping of Brachyura crabs, diverging the earliest in the evolutionary history, around the Late Triassic or Early Jurassic. Below is a cladogram showing Dromiacea's placement within Brachyura: ^{[2] [3]}

The larvae of Dromiacea resemble those of the Anomura more closely than those of other crabs.^{[citation needed]} This may simply reflect their basal position in the crab phylogeny.

The superfamily Eocarcinoidea, containing Eocarcinus and Platykotta, was previously considered to be a member of the Dromiacea, but was transferred to the Anomura according to a 2011 study.^[4] However, a reanalysis in 2020 found it to be the earliest known stem-group crab within Brachyura.^[5]

The fossil record of Dromiacea reaches back at least as far as the Jurassic,^[6] and, if Imocaris is indeed a member, into the Carboniferous.^[7]

Dromiacea primarily consists of two groups of superfamilies - Dromioidea and Homoloidea. See the below cladogram:^[2]

Recent studies have found that some of the families may not be monophyletic, but rather paraphyletic.^[2]

• The Dromioidea family Dromiidae may be paraphyletic with respect to Dynomenidae
• The Homoloidea family Homolidae is paraphyletic with respect to Latreilliidae