Shovelbill Shark,
Discovery of a new species
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Figure 1: Representation and anatomical description of Shevelbill Shark, Sphyrna alleni sp. Nov.
Researchers have recently described a new species of hammerhead shark: Sphyrna alleni sp. nov. (Carcharhiniformes, Sphyrnidae), found in the Caribbean Sea and the south-western Atlantic Ocean (Gonzalez et al., 2024). It lives in coastal waters, estuaries, coral reefs, seagrass beds and sandy bottoms from Belize to Brazil.
Hammerhead sharks (family Sphyrnidae) are a complex group including Shyrna tiburo, a species previously divided into 3 subspecies: Sphyrna tiburo tiburo (found in the USA, Mexico and the Bahamas), Sphyrna. aff. tiburo (found in Belize, Panama, Colombia, Trinidad & Tobago and Brazil) and Sphyrna tiburo vespertina (in the eastern Pacific) (Aroca et al, 2022; Fields et al., 2016; Gonzalez et al., 2019, 2021; Naylor et al., 2012).
Although these sharks are very commonly caught by local fishermen in many Latin American countries, they remain little studied.
This new article, published on September 23rd 2024, focuses on the study of morphometry (measurement of certain physical parameters), meristics (characterisation of anatomical features) and genetic variations (information contained in the genes) of western Atlantic sharks (Gonzalez et al., 2024).
23 specimens of Sphyrna tiburo tiburo (from USA) and Sphyrna. aff. tiburo (from Belize) have been studied for the following characters:
> 61 morphometric mesurements;
> 3 meristic characters (count the number of pre-caudal vertebrae, upper and lower functional rows of teeth);
> Genetic markers (2 mitochondrial DNA markers and 12 nuclear DNA markers).
Which produced the following results:
> No significant morphometric difference between the two groups but the researchers notice that Sphyrna. aff. tiburo has a nore shovel-shape head than Sphyrna tiburo tiburo;
> Different numbers of vertebrae (80-83 for Sphyrna. aff. tiburo and 71-74 fro Sphyrna tiburo tiburo);
> Genetic markers clearly separate the two groups.
The study concludes that the two studied groups belong to two different species of shark in the western Atlantic and not two groups belonging to the same species: S. tiburo and S. alleni sp. nov., previously Sphyrna. aff. tiburo which is now described as a new species (Gonzalez et al., 2024).
Figure 2: Cephalofoils comparison (dorsal and ventral views of each specimen are provided). Scale bar: 5 cm. TL : Total length of the specimen. A) S. alleni sp. nov. ; B) S. tiburo. Pictures: Cindy Gonzalez. Figure from Gonzalez et al. (2024).
Figure 3: Sphyrna alleni sp. Nov. A) Horizontal view of the shark; B) dermal denticles; C) Upper and D) Lower teeth; Dorsal and ventral Représentation of the head shape of E) Female et F) Male. Illustrations: Gina Clementi. Figure from Gonzalez et al. (2024).
Bibliography / Bibliographie
Aroca, A. K., Tavera, J., and Torres, Y.: Molecular and morphological evaluation of the bonnethead shark complex Sphyrna tiburo (Carcharhiniformes: Sphyrnidae), Environ Biol Fish, 105, 1643–1658, https://doi.org/10.1007/s10641-022-01358-x, 2022.
Fields, A. T., Feldheim, K. A., Gelsleichter, J., Pfoertner, C., and Chapman, D. D.: Population structure and cryptic speciation in bonnethead sharks Sphyrna tiburo in the south‐eastern U.S.A. and Caribbean, Journal of Fish Biology, 89, 2219–2233, https://doi.org/10.1111/jfb.13025, 2016.
Gonzalez, C., Gallagher, A. J., and Caballero, S.: Conservation genetics of the bonnethead shark Sphyrna tiburo in Bocas del Toro, Panama: Preliminary evidence of a unique stock, PLoS ONE, 14, e0220737, https://doi.org/10.1371/journal.pone.0220737, 2019.
Gonzalez, C., Postaire, B., Domingues, R. R., Feldheim, K. A., Caballero, S., and Chapman, D.: Phylogeography and population genetics of the cryptic bonnethead shark Sphyrna aff. tiburo in BRAZIL and the CARIBBEAN inferred from mt DNA markers, Journal of Fish Biology, 99, 1899–1911, https://doi.org/10.1111/jfb.14896, 2021.
Gonzalez, C., Postaire, B., Driggers, W., Caballero, S., and Chapman, D.: Sphyrna alleni sp. nov., a new hammerhead shark (Carcharhiniformes, Sphyrnidae) from the Caribbean and the Southwest Atlantic., Zootaxa, 5512, 491–511, https://doi.org/10.11646/zootaxa.5512.4.2, 2024.
Naylor, G. J. P., Caira, J. N., Jensen, K., Rosana, K. A. M., White, W. T., and Last, P. R.: A DNA Sequence–Based Approach To the Identification of Shark and Ray Species and Its Implications for Global Elasmobranch Diversity and Parasitology, Bulletin of the American Museum of Natural History, 367, 1–262, https://doi.org/10.1206/754.1, 2012.
July 2025
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