Portunus

After Latin Portunus (Portunes, Portumnes), the Roman god of harbors and ports.

This etymology is incomplete. You can help Wiktionary by elaborating on the origins of this term. can we really derive it from the god's name?

Portunus m

1. A taxonomic genus within the family Portunidae – certain swimming crabs.

• (genus): Eukaryota – superkingdom; Animalia – kingdom; Bilateria – subkingdom; Protostomia – infrakingdom; Ecdysozoa – superphylum; Arthropoda – phylum; Crustacea – subphylum; Malacostraca – class; Eumalacostraca – subclass; Eucarida – superorder; Decapoda – order; Pleocyemata - suborder; Brachyura - infraorder; Eubrachyura - section; Heterotremata - subsection; Portunoidea - superfamily; Portunidae - family; Portuninae - subfamily

• (genus): Portunus pelagicus (flower crab) - type species; Portunus anceps, Portunus sanguinolentus (three-spot swimming crab, blood-spotted swimming crab, red-spotted swimming crab), Portunus sayi (sargassum swimming crab), Portunus segnis (African blue swimming crab), Portunus trituberculatus (gazami crab), Portunus ventralis - selected other species; for other species see Portunus on Wikipedia.Wikipedia

• Portunus on Wikipedia.Wikipedia
• Portunus on Wikispecies.Wikispecies
• Portunus on Wikimedia Commons.Wikimedia Commons
• Portunus at National Center for Biotechnology Information
• Portunus at Integrated Taxonomic Information System.
• Portunus at World Register of Marine Species

• Portumnus

From an unattested adjectival form of portus seen in opportūnus and importūnus. Ultimately from portus (“port, harbour”) +‎ -nus (see -īnus). Compare lacūna.

• (Classical Latin) IPA^(key): /porˈtuː.nus/, [pɔrˈt̪uːnʊs̠]
• (modern Italianate Ecclesiastical) IPA^(key): /porˈtu.nus/, [porˈt̪uːnus]

Portūnus m sg (genitive Portūnī); second declension

1. a minor Roman god, protector of harbors, also called Palaemon

Second-declension noun, singular only.

• Portūnālis
• Portūnālia

• “Portunus”, in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
• Portunus in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette.