A New Species of Hatschekia (Copepoda: Dichelesthiidae) Parasitic on Leopard Coral Trout in the Great Barrier Reef, Australia

Abstract

Hatschekia plectropomi sp. n. is described based on the specimens taken from Plectropomus leopardus (Lacepede) collected from Wistari Reef, Heron Island, and Lizard Island of the Great Barrier Reef, Australia. There are two known records of Hatschekia reported from Australia, but none from the Great Barrier Reef. Heegaard (1962) described H. elongata, which he (1964) renamed H. thompsonii, from Brachaluteres jacksonianus washed ashore at Cronulla Beach, near Port Hacking, New South Wales, and Kabata (1965) described H. modesta from Upeneichthys porosus (Cuvier et Valenciennes) which was collected east of Albany, Western Australia. Specimens of the new species treated below were collected by Dr. K. Rohde, while director of the Heron Island Research Station, Queensland, Australia. We would like to thank Dr. Rohde for his kindness and generosity in placing his collection of copepod parasites at our disposal. Hatschekia plectropomi sp. n. (Figs. 1-11) Material examined: 87 ovigerous and juvenile 9 9 on gills of Plectropomus leopardus (Lacepede). From Wistari Reef: 12 ovigerous and 3 juveniles from a 58 cm long host, 4 November 1973; 3 ovigerous and 2 juveniles from a 63 cm long host, 4 November 1973; 17 ovigerous and 2 juveniles from a 45 cm long host, 11 November 1973 (holotype, USNM 170547, and 10 paratypes, USNM 170548, selected from this collection are deposited in the U.S. National Museum of Natural History, Smithsonian Institution, Washington, D.C.); 8 ovigerous and 1 juvenile from 62 cm long host, 4 December 1973; 8 ovigerous from a 50 cm long host, 5 January 1974; 1 ovigerous from a 50 cm long host, 29 May 1974. From Heron Island: 6 ovigerous (no host length recorded), 2 Received for publication 27 January 1978. *Department of Biology, California State University, Long Beach, California 90840. t Boston University Marine Program, Marine Biological Laboratory, Woods Hole, Massachusetts 02543. September 1973; 3 ovigerous from a 68 cm long host, 4 December 1973; 10 ovigerous from a 78 cm long host, 28 January 1974. From Lizard Island: 8 ovigerous from a 31 cm long host, 23 April 1975. Female: Body (Fig. 1) long, with flattened ventral surface. Head wider than long, with a rounded margin extending posteriorly into trunk. Distinct cuticular ribs on dorsal surface of head. First and second pedigerous somites short and incompletely fused. Third and fourth pedigerous segments completely fused to form a long trunk bearing a prominent lateral swelling on either right or left side. Genital segment (Fig. 2) small, attached to ventral surface of trunk. Egg sacs attached to posterodorsal surface of genital segment. Abdomen (Fig. 2) distinctly wider than long, bearing a pair of small setules on posterodorsal surface. Caudal ramus about 3 times longer than wide, armed with 6 unequal setae (3 plumose, 3 naked). First antenna (Fig. 3) 3-segmented, with stout basal portion covered by a semi-transparent membrane. Armature of these segments being: 9, 10, and 12 + 1 aesthete. Second antenna (Fig. 4) a strong prehensile apparatus bearing numerous microtubules on its huge second segment. These tubules appear as minute scales on surface of cuticle. Terminal segment a simple recurved hook. Base of second antenna lacking papilla. Mandible (Fig. 5) stubby, bearing 3 stout teeth. Maxilla (Fig. 6) small, consisting of 2 lobes, each bearing 2 processes. Maxilliped (Fig. 7) long, slender, and 4-segmented; second and third segments each bearing a seta; terminal segment bearing a break on its cuticle and a forked tip. Both leg 1 (Fig. 8) and leg 2 (Fig. 9) biramous, with 2-segmented rami bearing rows of spinules only on their anterior surfaces. Armature on these legs as follows: Leg 1 Protopod 1-1 Exopod 1-0; 6 Endopod 0-0; 5 Leg 2 Protopod 1-0 Exopod 1-0; 5 Endopod 0-1; 5 Leg 3 (Fig. 10) represented by a small lobe tipped with 2 plumose setae and leg 4 (Fig. 11), with 1 plumose seta. Measurements (in Ium):