Lernanthropus gisleri van Beneden, 1852

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 : 47-48

Lernanthropus gisleri van Beneden, 1852

( Fig. 20 C–E)

Non: L. gisleri: Yamaguti, 1936

Material examined: 6♀♀, 4♂♂ from Argyrosomus japonicus (Temminck & Schlegel, 1845) , Port River , South Australia; 02 September 2007; collected by K.S. Hutson ; 2♀♀, 1♂, NHMUK Reg. No. 2007.994–946, and 4♀♀, 3♂♂, SAMA Reg. No. C6889 . 1♀ from A. japonicus, Coffs Harbour , New South Wales; February 1982; collected by K. Rohde. 8♀♀, 3♂♂ from A. japonicus, Coffs Harbour , New South Wales; February 1982; collected by K. Rohde. 8♀♀, 3♂♂ from A. japonicus, Coffs Harbour , New South Wales; February 1982; collected by K. Rohde ; NHMUK Reg. No. 1984.94–96 .

Differential diagnosis: Cephalothorax longer than wide with almost linear lateral margins ( Fig. 20C ). Anterior part of trunk just wider than, and about twice as long as, cephalothorax and with more-or-less parallel lateral margins. Posterior part of trunk (fourth pedigerous somite) narrowest anteriorly at level of origin of third legs and with dorsal trunk plate increasing in width posteriorly towards strongly convex posterior margin; dorsal trunk plate about 1.15 times longer than anterior part of trunk. Urosome comprising fifth pedigerous somite, genital complex and abdomen, all fused. Paired caudal rami elongate; fully concealed beneath dorsal trunk plate. Leg 3 ( Fig. 20D ) forming ventrolaterally directed, elongate lobe, just slightly longer than anterior part of trunk; endopodal lobes entirely separate in mid-line: exopod not defined. Leg 4 bilobate; both lobes elongate, lanceolate; outer lobe slightly longer than inner: lobes almost as long as entire body and both protruding well beyond free posterior margin of dorsal plate. Leg 5 elongate, with tips just visible at posterior margin of dorsal trunk plate. Body lengths of 2 ♀♀ 8.80 and 8.90 mm (based on females from A. japonicus ): male ( Fig. 20E ) body length 3.10 mm.

Distribution: Lernanthropus gisleri is primarily a parasite of sciaenid fishes and was originally described from European waters (van Beneden, 1852). It has since been widely reported from both sides of the North Atlantic and in the Mediterranean Sea ( Table 3). It was first reported from Australian waters by Kabata (1979a) who examined two lots of Lernanthropus in the collections of the University of Adelaide, one labelled from “Port Willunga” and the other “probably New South Wales”, and identified them as L. gisleri . The hosts were Argyrosomus japonicus (as Sciaena antarctica Castelnau ) and Selenotoca multifasciatus (Richardson, 1846) (as Scatophagus multifasciatus ). Kabata (1979a) did not provide any description based on his Australian material, instead referring to his redescription of L. gisleri in Kabata (1979b) which was based on specimens collected from Scotland.

As noted above, L. gisleri has also been reported from Japan on Sciaena sp. ( Yamaguti, 1936) and from China on Johnius dussumieri (as Sciaena dussumieri ) ( Song & Chen, 1976). Koyuncu et al. (2012) considered that Yamaguti’s (1936) report of L. gisleri was based on a misidentification and that his material “does not belong to L. gisleri ”. They concluded that “his specimen probably represents a new species”. On the basis of the brief description provided by Yamaguti (1936) his Japanese material is here re-identified as L. elegans sp. nov., described above.

Remarks. Kabata (1979a) did not record the length of the females he reported from Australian waters but the females reported here from Argyrosomus japonicus caught in South Australia, have a mean body length of 8.90 mm. The long slender body form of this material ( Fig. 20C, D ) corresponds closely to that of the Scottish material figured by Kabata (1979b). Females of L. gisleri collected from Argyrosomus regius (Asso, 1801) caught off the South coast of England and stored in the NHMUK collections (Reg. No. 1960.1.19.2) exhibited a mean body length of 9.04 mm (range 8.9 to 9.2 mm, based on 5 specimens). The female body length is very similar despite the geographical separation of these records.

Based on Kabata & Gusev’s (1966) study of L. gisleri material collected from Argyrosomus hololepidotus (Lacepède, 1801) (as Johnius hololepidotus ) caught off the west coast of Africa, Kabata (1979b) considered that L. gisleri varied in size according to geographical area. The body length of females from Argyrosomus regius caught off the Scottish coast ranged from 9.6 to 11.0 mm, compared to 6.2 mm for the African females. Kabata & Gusev (1966) also noted differences in the third legs, which were shorter relative to body length in the African material, and in body proportions. We consider that the disparity in body size taken together with these morphological differences indicate that the African material probably belongs to another related species, such as L. francai , which has a body length of about 6 mm and occurs off the West African coast. This possibility requires further investigation.

Figures

FIGURE 20. Lernanthropus elegans sp. nov., paratype ♂, A, leg 1; B, leg 2. Lernanthropus gisleri van Beneden, 1852, adult ♀, C, habitus, dorsal; D, habitus lateral. Adult ♂, E, habitus, dorsal. Scale bars A,B, 50 μm, C,D, 2 mm, E, 1 mm.