Huffmanela selachii n. sp. (Nematoda: Trichosomoididae: Huffmanelinae): A new species infecting the skin of the great hammerhead shark (Sphyrna mokarran) and the blacktip reef shark (Carcharhinus melanopterus) in the Arabian Gulf, off-shore Saudi Arabia

From January 2017 -December 2019, 75 out of 850 (8.8 %) great hammerhead sharks from the Arabian Gulf had skin lesions of black irregular discolorations on the ventral surface of the head. The lesions con-sisted of pencil-like lineations often advancing forward by about 2 mm in back-and-forth looped scrib-bles often forming a relatively linear bands of about 5-7 cm wide. Similar lesions were also found in the blacktip reef shark from the same area within the same period, and consisted of straight to irregular black lines, extended indiscriminately across the skin of the sharks. Microscopic examination of the skin revealed the presence of dark-brown eggs exhibiting the spindle or ellipsoidal eggs characteristic of Huffmanela sp. The morphometrics of eggs from both hosts were similar (62.9-89.9 lm long and 29.3- 56.1 lm wide). The eggshells were smooth with polar plugs protruding or not, with an abruptly truncated crown-like or shoulder-like collar surrounding the plug. The eggs were only found in the epidermal layer of the skin. Based on the unique morphometrics of the eggs, we report a new species, named: Huffmanela selachii n. sp.. This appears to be the first report of Huffmanela from either the great hammerhead shark or the blacktip reef shark, and the third reported Huffmanela in sharks from the Arabian Gulf. It is also one of few species reported from connecting waters of the greater Indian Ocean. This new finding contributes to our understanding of the diversity and ubiquity of Huffmanela sp. in marine creatures.(c) 2022 The Author(s). Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

This study reveals the presence of skin lesions caused by Huffmanela sp. eggs on great hammerhead sharks and blacktip reef sharks in the Arabian Gulf. The unique morphometrics of the eggs led to the discovery of a new species named Huffmanela selachii n. sp. This finding contributes to our understanding of the diversity and ubiquity of Huffmanela sp. in marine creatures, marking the first report of Huffmanela on these shark species in the Arabian Gulf.