Huffmanela sp. (Nematoda: Trichosomoididae: Huffmanelinae) encountered in the whitecheek shark (Carcharhinus dussumieri) in the Arabian Gulf

Abstract

Summary Veterinary inspection of fish caught at the western side of the Arabian Gulf off the shore of Saudi Arabia in 2017 revealed abnormal irregular zigzag black lines in the skins of 135 out of 1500 (prevalence = 9 %) whitecheek sharks (Carcharhinus dussumieri). These lesions have been noticed in the dorsal and ventral part of the head near the snout and around the eyes, as well as in the skin of the pectoral fins. The parasitological, pathological and ultramorphological aspects of the sampled fish were studied using a light microscope, as well as scanning and transmission electron microscopes. Trichosomoidid-type eggs identified as Huffmanela sp. were found in the superficial layer of the skin. The mature eggs containing larvae (n = 75) were ellipsoidal or spindle-shaped, smooth-shelled, amber-brown to dark brown or even black in colour. The width of the eggs ranged from 34 to 49μm with lengths ranging from 95 to 107μm. The polar plugs of the immature eggs were slightly protruding, whereas mature eggs had clearly protruding polar plugs. The width of the polar plugs ranged from 4.5 – 9.5μm. The shells of the eggs were smooth and there was a thin layer seen near the polar areas. The infected skin exhibited desquamated epithelium, with inflammatory cell aggregations and melanophores in the debris. The underlying musculatures of the skin were free from any eggs, but showed mild pathological changes, including congestion of blood vessels, haemorrhages and oedema. The prevalence of infection showed seasonality, peaking significantly in the spring (18.18 %), with comparable prevalence rates in winter and summer (9.43 % and 8.57 %, respectively). However, infections dropped significantly during the autumn months (3.75 %). It is believed that this is the first study reporting the presence of Huffmanela sp. in whitecheek sharks at El-Jubail Province, Saudi Arabia, Arabian Gulf.

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

“…No eggs were present in the underlying skin layers. Similar observations were also reported elsewhere in Huffmanela infections in sharks ( Justine, 2005 , MacLean et al, 2006 , Bullard et al, 2012 , and Attia et al, 2021b ).…”

“…The remaining record of a recently reported Huffmanela sp. in the skin of whitecheek sharks, also in the Arabian Gulf ( Attia et al, 2021b ). These worms may belong to Huffmanela selachii n. sp.…”

“…and the previous report of Huffmanela sp. by Attia et al (2021b) , the worms in the latter population should be considered conspecific with H. selachii n. sp.…”

“…Similar skin lesions have been described previously in other shark species and were attributed to the presence of eggs of Huffmanela spp. ( Ruiz and Bullard, 2013 , Attia et al, 2021b ).…”

“…Recently, two innominate species of Huffmanela were reported by Attia et al (2021b) from the skin of the whitecheek shark ( Carcharhinus dussumieri (Valenciennes, 1839)) and from muscular tissues of the orange spotted grouper ( Epinephelus coioides ) from the Arabian Gulf ( Attia et al, 2021a ). In the latter two reports, the identification of the eggs was conducted to the genus level, and to the best of the authors’ knowledge, Huffmanela infections have never been reported from the great hammerhead sharks nor the blacktip reef sharks.…”