Named for the weird and distinctive type of their heads, hammerhead sharks belong to the household Sphyrnidae.
They’re discovered worldwide, preferring life in hotter waters alongside coastlines and continental cabinets.
“Hammerhead sharks are a monophyletic lineage of carcharhiniform sharks first showing within the Miocene epoch,” mentioned Florida Worldwide College researcher Cindy Gonzalez and her colleagues from the US and Canada.
“They’re characterised by their laterally expanded, dorsoventrally compressed head or ‘cephalofoil’ and at present comprise 9 named species.”
“Hammerhead sharks are some of the threatened shark households primarily because of overexploitation, with all species however one (Sphyrna gilberti) being globally listed as Susceptible, Endangered, or Critically Endangered by the IUCN,” they added.
“There are 4 species of small-bodied hammerheads (lower than 1.5 m complete size at first maturity) which are endemic to the Americas: Sphyrna tiburo, Sphyrna tudes, Sphyrna corona, and Sphyrna media.”
“Sphyrna corona happens solely within the Jap Pacific, Sphyrna tudes happens solely within the Western Atlantic, and two species happen in each oceanic basins, together with the scoophead shark (Sphyrna media) and the bonnethead shark (Sphyrna tiburo).”
The newly-described Sphyrna species is a small hammerhead shark lower than 1.5 m in size.
Scientifically named Sphyrna alleni (widespread title is the shovelbill shark), it has a flat, shovel formed head that lacks indentations on its anterior edge.
“Sphyrna alleni is distinct from Sphyrna tiburo as a result of on this species the anterior margin of the pinnacle is extra rounded and the lobules on the posterior margin aren’t current,” the researchers mentioned.
“Precaudal vertebral counts for Sphyrna alleni are between 80 and 83 — round 10 extra vertebrae than in Sphyrna tiburo.”
“Given some similarity in cephalofoil form in Sphyrna alleni and Sphyrna vespertina it’s attainable that they’re sister lineages and Sphyrna tiburo diverged from them because it expanded into the subtropical and temperate Atlantic, with a later separation of Sphyrna vespertina and the incipient Sphyrna alleni by the Isthmus closure.”
Sphyrna alleni is distributed in coastal waters, estuaries, coral reefs, seagrass beds, and sand bottoms from Belize to Brazil.
The presence of the species has been confirmed within the Caribbean in Belize, Panama, Colombia, Trinidad and Tobago, and within the southwestern Atlantic in Brazil.
“Bonnetheads are at present assessed as Globally Endangered by the IUCN however they’ve been assessed as one amphi-American species,” the scientists mentioned.
“The evaluation highlights that the species is properly managed in increased latitude elements of its northern hemisphere Atlantic vary (U.S., Bahamas) however closely fished and poorly managed elsewhere, with proof of inhabitants collapse in Brazil and all through a lot of the Tropical Jap Pacific.”
“Reevaluating this evaluation contemplating the geographic distribution of Sphyrna tiburo and Sphyrna alleni is now warranted,” they mentioned.
“Given how fishing and administration is distributed it’s doubtless that the IUCN standing of Sphyrna tiburo would enhance and Sphyrna alleni would warrant a extremely threatened standing.”
“Better administration consideration is important to rebuild populations of Sphyrna alleni, which may take the type of restrictions on gillnets and trawls as these gear varieties are accountable for most catches of this coastal species.”
The invention of Sphyrna alleni is reported in a paper within the journal Zootaxa.
Quotation:
Cindy Gonzalez et al. 2024. Sphyrna alleni sp. nov., a brand new hammerhead shark (Carcharhiniformes, Sphyrnidae) from the Caribbean and the Southwest Atlantic. Zootaxa 5512 (4): 491-511; doi: 10.11646/zootaxa.5512.4.2
This article by Natali Anderson was first revealed by Sci Information on 4 October 2024. Lead Picture: Sphyrna alleni, a male collected in Riversdale, Belize. Picture credit score: Cindy Gonzalez.
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