Austruca perplexa

{{Short description|Species of crab}}

{{Speciesbox

| image = Fiddler Crab - Australia.jpg

| genus = Austruca

| species = perplexa

| authority = (H. Milne-Edwards, 1837) {{cite journal |journal=Raffles Bulletin of Zoology |year=2008 |volume=17 |pages=1–286 |title=Systema Brachyurorum: Part I. An annotated checklist of extant Brachyuran crabs of the world |author=Peter K. L. Ng |author2=Danièle Guinot |author3=Peter J. F. Davie |name-list-style=amp |url=http://rmbr.nus.edu.sg/rbz/biblio/s17/s17rbz.pdf |access-date=2010-01-16 |archive-date=2011-06-06 |archive-url=https://web.archive.org/web/20110606061453/http://rmbr.nus.edu.sg/rbz/biblio/s17/s17rbz.pdf |url-status=dead }}

| display_parents = 3

| synonyms =

• Gelasimus perplexus H. Milne-Edwards, 1837
• Uca annulipes var. albimana H. Milne-Edwards, 1852
• Uca lactea perplexa (H. Milne-Edwards, 1837)
• Uca perplexa (H. Milne-Edwards, 1837)

}}

File:Uca perplexa male waving.gifAustruca perplexa is a species of fiddler crab. It is found from the Ryukyu Islands, Japan to India, throughout the Malay Archipelago, along eastern Australian coasts from Queensland to New South Wales, and in various Pacific islands, including Fiji, Tonga and Vanuatu.{{cite web |url=http://www.environment.gov.au/biodiversity/abrs/online-resources/fauna/afd/taxa/Uca_perplexa |work=Australian Faunal Directory |publisher=Department of the Environment, Water, Heritage and the Arts |title=Species Uca perplexa (H. Milne Edwards, 1852) |date=October 9, 2008}}{{cite web |url=http://www.species-identification.org/species.php?species_group=crabs_of_japan&menuentry=soorten&id=1771&tab=beschrijving |title=Uca perplexa |work=Crabs of Japan |publisher=Marine Species Identification Portal}}

Austruca perplexa was formerly in the genus Uca, but in 2016 it was placed in the genus Austruca, a former subgenus of Uca.

As in other fiddler crabs, the male has a greatly enlarged claw, which is used for signalling. The higher the claw is waved by the male, the greater his chance of attracting a female; the size of the claw is therefore subject to sexual selection.{{cite journal |journal=Evolution |volume=63 |issue=9 |pages=2363–2371 |year=2009 |title=The cost of reliable signaling: experimental evidence for predictable variation among males in a cost-benefit trade-off between sexually selected traits |author=Minoru Murai |author2=Patricia R. Y. Backwell |author3=Michael D. Jennions |name-list-style=amp |doi=10.1111/j.1558-5646.2009.00726.x |pmid=19453725|doi-access=free }} Furthermore, larger male fiddler crabs wave their claws at a faster rate than smaller fiddler crabs to attract larger females. Larger females are more desirable because they produce more eggs than smaller females.{{Cite journal |last=Tina |first=Fahmida Wazed |last2=Muramatsu |first2=Daisuke |date=October 2019 |editor-last=Bertram |editor-first=Susan |title=Size‐dependent mating preference of the male fiddler crab Austruca perplexa |url=https://onlinelibrary.wiley.com/doi/10.1111/eth.12961 |journal=Ethology |language=en |volume=126 |issue=1 |pages=68–75 |doi=10.1111/eth.12961 |issn=0179-1613|url-access=subscription }}

Austruca perplexa is usually found on sandy substrates near river mouths or on sheltered beaches in the mid-intertidal zone, usually near mangroves.{{cite web | url=http://queenslandcoast.blogspot.com.au/2015/04/guide-to-fiddler-crabs-of-queensland.html | title=Queensland Coast: Guide to Fiddler Crabs of Queensland | date=4 April 2015 }}{{clear_left}}