Aethon morelandi Hewitt, 1968

Boxshall, Geoff A., Bernot, James P., Barton, Diane P., Diggles, Ben K., Q-Y, Russell, Atkinson-Coyle, Toby & Hutson, Kate S., 2020, Parasitic copepods of the family Lernanthropidae Kabata, 1979 (Copepoda: Siphonostomatoida) from Australian fishes, with descriptions of seven new species, Zootaxa 4736 (1), pp. 1-103 : 13-14

Aethon morelandi Hewitt, 1968

( Fig. 5 )

Material examined: 20♀♀, 18♂♂ on Nemadactylus macropterus (Forster, 1801) , Coffs Harbour , New South Wales, collected by K. Rohde; NHMUK Reg. No. 1982.86 . 1♂ from N. macropterus, Coffs Harbour , New South Wales, 15 November 1981; collected by K. Rohde; NHMUK Reg. No. 1992.163–172 . 1♀ from “Morwong” (Chei- lodactylidae), Port Macquarie , New South Wales, 01 September 1980; collected by K. Rohde; NHMUK Reg. No. 1992.153–162 . 1♀ from Nemadactylus valenciennesi (Whitley, 1937) , Port MacDonnell , South Australia, collected by K.S. Hutson, 09 May 2007, SAMA Reg. No. C 6891 .

Differential diagnosis: Cephalothorax markedly wider than long, with distinct dorsal cephalothoracic shield; lateral margins with 2 pairs of lateral processes ( Fig. 5 A–C), posterior pair much longer than anterior pair; tips of both pairs with papillate surface ornamentation. Trunk distinctly wider than cephalothorax: anterior part with 2 well-defined dorsal tergites derived from second and third pedigerous somites, posterolateral margins extended into pointed posterolateral processes; posterior part of trunk (fourth pedigerous somite) covered by dorsal trunk plate. Plate just longer than wide, with evenly but weakly convex lateral margins; posterior margin with deep median indentation and shallower lateral indentations ( Fig. 5A ). Looped egg strings entirely concealed beneath dorsal trunk plate in dorsal view. Urosome comprising fifth pedigerous somite, genital complex and 1-segmented abdomen all fused. Anal somite bearing paired caudal rami, each 1.3 times longer than wide, with bluntly rounded apex. Leg 2 with endopod fused to protopod forming curved process bearing reduced exopod as small protuberance on outer side of process. Leg 3 large, comprising 2 lamellate lobes; outer lobe (exopod) rigid and highly sclerotised, orien- tated vertically and running length of trunk plate, forming side wall of cavity containing loosely coiled egg strings; external surface of outer lobe with papillate surface ornamentation: inner lobe (endopodal) orientated horizontally and extending posteriorly about to end of trunk plate; inner lobe fleshy, lacking surface ornamentation. Leg 4 bilobate; both lobes lamellate with rounded tip, inner lobe shorter than outer. Mean body length of ♀ 4.33 mm and of ♂ 1.66 mm (length data from Boxshall, 1989).

Distribution: This species was originally described from New Zealand waters on the latrid Latridopsis ciliaris (Forster, 1801) ( Hewitt, 1968) . The first record from Australia was from Coffs Harbour (New South Wales) on the cheilodactylid Nemadactylus macropterus ( Boxshall, 1989) . A subsequent record of this species from N. valenciennesi caught in South Australia is reported here.

Remarks: Aethon morelandi was established on the basis of three females found on the gills of Latridopsis ciliaris caught at Ngaraunga near Wellington, New Zealand ( Hewitt, 1968). The male was subsequently described from the same host caught at Portobello, east of Dunedin, New Zealand ( Rohde et al., 1980). Both sexes were redescribed in detail by Boxshall (1989), based on material from Coffs Harbour.

Figures

FIGURE 5. Aethon morelandi Hewitt 1968, adult ♀. A, habitus, dorsal; B, habitus, lateral; C, habitus, ventral. Scale bar 2 mm.