George W. Benz

A second species of Arctic shark: Pacific sleeper shark Somniosus pacificus from Point Hope, Alaska

We report a dead, 229-cm-long Pacific sleeper shark, Somniosus pacificus, discovered in 1998 along the shore at Point Hope, Alaska. This is the first definitive record of this species from within the Arctic Circle, the first definitive report of a shark from the Chukchi Sea, and the first report of a shark other than a Greenland shark from within the Arctic Circle.

Pugnose eels, Simenchelys parasiticus (Synaphobranchidae) from the heart of a shortfin mako, Isurus oxyrinchus (Lamnidae)

A 395 kg shortfin mako, Isurus oxyrinchus (Lamnidae) landed at Montauk, New York in June of 1992 was found to contain two dead, but otherwise healthy appearing pugnose eels, Simenchelys parasiticus (Synaphobranchidae) within the lumen of its heart. The path along which the eels made their way into the sharks heart was not found. Histological examination of the sharks heart revealed the presence of medial hyperplasia and hypertrophy of small arterioles, multifocal arteriosclerosis, and relatively high numbers of capillaries per unit area. These phenomena were not observed in similar sections taken from hearts of six uninfected mako sharks. The stomachs of both eels were filled with blood, suggesting that they had been within the shark at least long enough to feed. Consideration of this new record along with the literature supports a trophic designation of facultative endoparasite for the species Simenchelys parasiticus.

GILL LESIONS ASSOCIATED WITH ERPOCOTYLE TIBURONIS (MONOGENEA: HEXABOTHRIIDAE) ON WILD AND AQUARIUM-HELD BONNETHEAD SHARKS (SPHYRNA TIBURO)

Gill lesions associated with infections of Erpocotyle tiburonis (Brooks, 1934) (Monogenea: Hexabothriidae) on wild bonnethead sharks (Sphyrna tiburo (L., 1758) (Carcharhiniformes: Sphyrinidae)) were compared with those on aquarium-held ones using light and scanning electron microscopy. Uninfected gill filaments had slender, triangular, smooth-surfaced lamellae and interlamellar water channels that were approximately equal in size. Four wild sharks were each infected by 3–11 widely separated adult E. tiburonis, and 1 of these sharks hosted a juvenile specimen. Lamellae flanking or touching adult E. tiburonis were pushed aside or bent, but were otherwise identical to those of uninfected filaments. Two aquarium-held sharks were each infected by hundreds of juvenile and adult E. tiburonis. In these sharks, lamellae near juveniles were pushed apart or bent, but were otherwise normal, whereas a thick, ragged-surfaced layer of hyperplastic epithelium both filled interlamellar water channels and partially or completely covered lamellae near adults. Results of this study suggest that the intense infections of E. tiburonis were facilitated by captivity and caused severe hyperplastic lesions that ultimately led to the death of the sharks by reducing or blocking the respiratory water flow over lamellae and thus reducing the exchange of gases and ions across the lamellar epithelium. In contrast, the wild sharks were infected by fewer worms and exhibited relatively minor lesions.

OCULAR LESIONS ASSOCIATED WITH ATTACHMENT OF THE COPEPOD OMMATOKOITA ELONGATA (LERNAEOPODIDAE: SIPHONOSTOMATOIDA) TO CORNEAS OF PACIFIC SLEEPER SHARKS SOMNIOSUS PACIFICUS CAPTURED OFF ALASKA IN PRINCE WILLIAM SOUND

Twenty eyes from 10 Pacific sleeper sharks Somniosus pacificus, infected with the copepod Ommatokoita elongata, were collected in Prince William Sound, Alaska, and the eyes of an additional 18 S. pacificus captured in the same area were inspected for copepods. Prevalence of infection by adult female O. elongata was 97% (n = 28); mean intensity of infection was 1.89 (±1SD = 0.32) adult female copepods per infected shark and 1.0 (±1SD = 0.0) adult female copepods per infected eye. Five of the 20 collected eyes were infected by O. elongata chalimi, and 9 of 20 eyes had 1 to several remnants of bullae embedded in the cornea. Bullae were each associated with a corneal opacity, and anchoring plugs of chalimi were associated with pinpoint lesions in the cornea or conjunctiva. All eyes exhibited marked edema and erosion of the bulbar conjunctiva, and this torus-shaped lesion corresponded to each O. elongata adult females presumed feeding and abrasion radius. Histological examinations revealed lesions in the anterior segment of eyes to be generally similar, but graded, in severity, and in all eyes they involved the conjunctiva, cornea, filtration angle, and iris. Epithelial lesions were characterized by corneal ulceration, dysplasia, hyperplasia, and heterophilic keratitis, and by ulcerative conjunctivitis accompanied by epithelial hyperplasia with rete peg formation. Disorganization of fibers, necrosis, mineralization, minimal heterophilic influx, and perilimbic neovascularization were associated with bullae in the corneal stroma. Within the limbus there was diffuse histiocytic and lymphocytic inflammation and marked lymphofollicular hyperplasia. Heterophilic and mononuclear anterior uveitis affecting the filtration angle and anterior surface of the iris was also observed in most eyes. One eye had a partial transcorneal prolapse of a ruptured lens, with degenerative changes in the ruptured lens and severe keratitis associated with the anchoring devices of an adult copepod and several chalimi. Fourteen eyes exhibited 1 to several, randomly distributed, small, round to irregular, corneal opacities or pits that were not associated with copepods, and it is likely that these opacities represented lesions associated with adult female or larval anchoring devices from past infections. The avascular cornea represents a niche that is somewhat shielded from host immune reactions, and this, and the fact that the general body surface of sleeper sharks is covered by tall and sharp placoid scales, may partially explain the corneal attachment of O. elongata adult females. It was concluded that O. elongata infections can lead to severe vision impairment in Pacific sleeper sharks but that these infections do not significantly debilitate hosts because they probably do not need to rely on acute vision for their survival.

Observations on the Attachment Scheme of the Parasitic Copepod Pandarus satyrus (Copepoda: Pandaridae)

penetrated the liver showed no noteworthy changes except for GPT, which increased up to 170 Karmen Units at 3 and again at 10 wk after exposure. Although the significance of this change is not fully understood, liver damage may be involved. Several species of mammals as well as coldblooded vertebrates have been shown to act as the paratenic hosts, suggesting a broad paratenic host-range and suggesting that humans run the risk of exposure to this parasite. al species of mammals as well as cold-

Five Species of Parasitic Copepods (Siphonostomatoida: Pandaridae) from the Body Surface of a White Shark Captured in Morro Bay, California

Five pandarid (Copepoda) species, Dinemoura producta, D. latifolia, Echthrogaleus coleoptratus, Pandarus bicolor, and Achtheinus oblongus, were collected from the external body surface of a white shark, Carcharodon carcharias, taken from Morro Bay in the northeastern Pacific Ocean off central California. This is the first report of parasitic copepods collected from C. carcharias captured in the northeastern Pacific along the West Coast of North America. It is proposed that the species-rich infections of some white sharks may be the result of the wide wanderings of individual sharks through waters inhabited by other elasmobranchs.

Skin Lesions Caused by Dermophthirius penneri (Monogenea: Microbothriidae) on Wild-Caught Blacktip Sharks (Carcharhinus limbatus)

Skin lesions caused by the ectoparasite Dermophthirius penneri Benz, 1987 (Monogenea: Microbothriidae) on 2 wild-caught blacktip sharks (Carcharhinus limbatus) from the northern Gulf of Mexico were studied using light and scanning electron microscopy. Grossly, lesions appeared as multifocal, well-demarcated, ovoid or irregularly shaped, light gray patches of skin. Scanning electron microscopy of lesions revealed gaps between placoid scales apparently created by detachment and loss of placoid scales, rotated and tilted placoid scales with blunt distal tips and shallow ridges, and a frayed epithelium that covered some placoid scales and filled some spaces between placoid scales. Light microscopy of lesions revealed epithelial hyperplasia accompanied by dermal infiltrates of moderate numbers of loosely arranged lymphocytes interposed between collagen bundles in the superficial layers of the stratum compactum. This report provides the first details of microbothriid skin lesions on wild sharks. Our results indicate that D. penneri caused chronic skin lesions not associated with bacterial infection or severe, debilitating, skin disease in the studied sharks.

FIRST DESCRIPTIONS OF EARLY- AND MIDDLE-STAGE COPEPODIDS OF ANTHOSOMA CRASSUM (DICHELESTHIIDAE: SIPHONOSTOMATOIDA) AND LESIONS ON SHORTFIN MAKOS (ISURUS OXYRINCHUS) INFECTED WITH A. CRASSUM

Early- and middle-stage copepodids of Anthosoma crassum (Dichelesthiidae: Siphonostomatoida) and lesions associated with A. crassum infections are described from samples collected from the jaws of shortfin makos captured off southern California. The copepodids did not possess frontal filaments or frontal organs, and they resided in a headstandlike position firmly attached by their embedded antennae. Copepod larvae and small adults were lodged in shallow mucosal ulcers that basally exhibited mild, acute granulocytic stomatitis; large adults were lodged in deep tunnels encompassing the anterior aspects of their bodies. Some lesions contained more than 1 copepod. Examinations of lesions revealed that A. crassum infection of shortfin makos can result in severe subacute, necrotizing stomatitis with hemorrhage, granulation tissue, and lymphocytic aggregations in the mucosa, and reactive lymphocytic infiltration of the submucosal skeletal muscle. Copepod gut contents consisted of shark erythrocytes, hemosiderin granules, and necrotic host cells. These observations, along with reports of sharks heavily infected with A. crassum, suggest that this copepod may sometimes play a role in the morbidity and mortality of sharks that it infects.

Redescription of Argulus melanostictus (Branchiura: argulidae) : a parasite of California grunion (Leuresthes tenuis: atherinidae), with notes regarding chemical control of A. melanostictus in a captive host population

Adult male and female Argulus melanostictus Wilson, 1935 are redescribed based on detailed examinations of a syntype and recently obtained specimens of both sexes collected from California grunion, Leuresthes tenuis, captured in nearshore Pacific waters at Monterey, California. A 14-16-hr seawater bath containing 0.5 microliter/L trichlorfon administered once weekly for 3 wk killed A. melanostictus while not noticeably harming grunion.

Huffmanela cf. Carcharhini (Nematoda: Trichosomoididae: Huffmanelinae) from Skin of a Sandbar Shark, Carcharhinus plumbeus, in the Pacific Ocean

Abstract: Eggs of Huffmanela cf. carcharhini from the skin of an aquarium-held, juvenile sandbar shark, Carcharhinus plumbeus, from the Pacific Ocean were studied using light and scanning electron microscopy. Grossly, eggs imparted a scribble-like skin marking approximately 130 × 60 mm on the right side of the sharks snout adjacent to its eye and nostril. Fresh (unfixed) eggs were elliptical, 75–95 µm long (x¯  =  85 µm, SD  =  ±4.5; n  =  75), 48–63 µm wide (53 ± 3.4; 75), 8–10 µm in shell thickness (9 ± 1.3; 27), 45–68 µm in vitelline mass length (52 ± 6.9; 8); had a smooth shell surface and nonprotruding polar plugs 8–13 µm wide (10 ± 1.5; 73); lacked thin filaments, superficial envelope, and shell spines; sank in 35 ppt artificial seawater; and did not spontaneously hatch after 12 hr in 35 ppt artificial seawater. Formalin-fixed eggs measured 193 days postfixation were 75–95 µm long (84 ± 3.9; 150), 45–60 µm wide (50 ± 2.2; 150), 5–10 µm in shell thickness (8 ± 1.2; 87), 45–60 µm in vitelline mass length (51 ± 3.0; 92), and 30–40 µm in vitelline mass width (33 ± 2.0; 84), and had nonprotruding polar plugs that were 10–15 µm long (11 ± 1.4; 93) and 8–10 µm wide (9 ± 1.1; 108). Forcibly hatched first-stage larvae (unfixed) were filiform, 188–273 µm long (212 ± 25.5; 13), 8–13 µm wide (10 ± 1.2; 13), and had fine transverse striations. Eggs infected the epidermis only. Histology revealed intra-epithelial inflammation with eosinophilic granulocytes and hyperplasia, plus dermal lymphofollicular hyperplasia associated with the infection. The eggs of H. cf. carcharhini likely undergo considerable ex utero development before being sloughed (unhatched) from the host, along with epidermal cells.