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Posted: Nov 23 2010

 Busycon sinistrum Hollister, 1958, Lightening Whelk

3/20/18:  The generic name has apparently changed, but dispute still remains as to the status of the species/subspecies naming.  Here's commentary as of 11/28/22:


Opinion per Harry Lee [An Obscure Whelk - Busycon laeostomum (]:

Species name:  Sinistrofulgur perversum (Linnaeus, 1758)

Subspecies names: 

     Sinistrofulgur perversum perversum (Linnaeus, 1758) - along the Yucatan peninsula

     Sinistrofulgur perversum sinistrum (Hollister, 1958) - northern and eastern Gulf of Mexico

     Sinistrofulgur perversum laeostomum (Kent, 1982) - Atlantic

Opinion per Gary Rosenberg (PDF) Gastropoda (Mollusca) of the Gulf of Mexico (

I don't agree with subspecies status for Sinistrofulgur laeostomum. The websites cited above don't mention that Rosenberg et al. (2009, Gastropoda (Mollusca) of the Gulf of Mexico) reevaluated the molecular evidence. Wise et al. (2004) considered S. sinistrum to be a subspecies of S. perversum. Their criterion for subspecies recognition was less than 2% observed DNA sequence divergence for cytochrome oxidase I, but this does not contradict a hypothesis that they are separate species, because recently evolved species might have little sequence divergence. The DNA data showed them to be reciprocally monophyletic. Also, there are many reports of S. perversum and S. sinistrum occurring in sympatry in the southern Gulf of Mexico, which contradicts subspecies status. Wise et al. (2004) suggested that the S. perversum morphology represents ecophenotypic variation in the presence of stone crabs, but did not present experimental evidence for induction of that morphology nor explain why stone crabs prey on Busyconidae in some areas and not others.

Ref:  J. Wise, M. G. Harasewych, R. T. Dillon Jr. (2004). Population divergence in the sinistral whelks of North America, with special reference to the east Florida ecotone (PDF; 673 kB). Marine Biology 145, pp. 1167–1179.  

See also: Lightning Whelks from Anastasia Island, Crescent Beach, FL, US on January 26, 2022 at 11:46 AM by Lin Wermager · iNaturalist 

For more photos see jaxshells

Busycon sinistrum a.jpg

The taxonomy in this book is questioned by many, but it's illustrations are very useful: Petuch, E. J.; Myers, R. F. & Berschauer D. P. (2015). The living and fossil Busycon whelks: Iconic mollusks of eastern North America. San Diego Shell Club.

Busycon sinistrum 19.jpg
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