Actumnus obesus

About Actumnus obesus

Actumnus obesus is a decapod crustacean in the family Pilumnidae. Its current scientific name is cited as Actumnus obesus Dana, 1852. Published Kauaʻi evidence documents the species from Port Allen reef and Port Allen Harbor. The cited evidence includes records dated or referenced to 2002. Evidence types include survey observation and museum voucher. These records establish a documented Kauaʻi occurrence but are not automatically interpreted as a present-day abundance estimate. The documented Kauaʻi habitat context includes nearshore reef and harbor / sheltered marine. Current island persistence, abundance, and population trend were not established by the occurrence material used for this record. The available Kauaʻi evidence does not support adding island-specific claims about diet, reproduction, behavior, population size, or trend unless those points are stated in the cited sources, so they are not inferred here. Keeping the accepted taxonomic concept together with the dated occurrence evidence allows later surveys to distinguish historical documentation from contemporary status.

This compact crab has a strongly domed carapace whose raised regions bear conspicuous granules. Short dense hairs fill the grooves between those regions, while longer hairs arise on the raised surfaces. Its front is divided into two lobes, and the curved front-side margin bears four pointed teeth. The claws are short, robust, and unequal; the walking legs are also stout and hairy. These structural details are more useful for identification than color alone. The Naturalis account, drawing on Takeda and Miyake’s treatment, gives Lahaina, Maui, as the type locality and records a broad Indo-Pacific distribution. Its listed range includes other Hawaiian islands, so the Kauaʻi survey evidence belongs within a wider regional taxonomic context. The description does not supply a Kauaʻi-specific body-size range or seasonal breeding schedule.