Lernanthropsis mugilii ( Shishido, 1898 )

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 : 15-16

Lernanthropsis mugilii ( Shishido, 1898)

( Fig. 6 )

Syn: Lernanthropus mugilii Shishido, 1898

Lernanthropus mugilis Shishido, 1898 (emended by Yamaguti, 1936)

Lernanthropus shishidoi Shiino, 1955

Lernanthropus nudus Bassett-Smith, 1898

Material examined: 9♀♀, 1♂ from Mugil cephalus Linnaeus, 1758 ( TC17257 ), Moreton Bay , Queensland, 18 January 2016; collected by G.A. Boxshall ; QM Reg. No. W29475 . 3♀♀, 1♂ from M. cephalus ( TC17120 ), Moreton Bay , Queensland, 14 January 2016; collected by G.A. Boxshall ; QM Reg. No. W29476 . 7♀♀, 1♂ from M. cephalus ( TC17170 ), Moreton Bay , Queensland, 15 January 2016; collected by G.A. Boxshall. 10♀♀, 1♂ from M. cephalus ( TC17714 , TC17715, TC17718 ), Moreton Bay , Queensland, 29 June 2016; collected by G.A. Boxshall. 5♀♀, 3♂♂ from M. cephalus ( TC17692 , TC17695 ), Moreton Bay , Queensland, 28 June 2016; collected by G.A. Boxshall. 5♀♀, 2♂♂ from M. cephalus ( TC 17763 , TC17783, TC17788 ), Moreton Bay , Queensland, 01 July 2016; collected by G.A. Boxshall. 12♀♀, 4♂♂ from M. cephalus ( TC17860 ), Moreton Bay , Queensland, 04 July 2016; collected by G.A. Boxshall ; NHMUK Reg. No. 2018.218–227 . 3♀♀, 3♂♂ from M. cephalus, Clarence River , New South Wales, 28 March 1981; collected by K. Rohde ; NHMUK Reg. No. 1984.91 . 14♀♀, 5♂♂ from M. cephalus, Coffs Harbour , New South Wales, February 1981; collected by K. Rohde ; NHMUK Reg. No. 1984.92 . 6♀♀, 2♂♂ from M. cephalus, Arrawarra Creek , New South Wales, 22 April 1981; collected by K. Rohde ; NHMUK Reg. No. 1984.93 .

Comparative material examined: Holotype female of Lernanthropus nudus Bassett-Smith, 1898 from Mugil sp. collected in Aden, BMNH Reg. No. 1898.12.2.12.

Differential diagnosis: Cephalothorax slightly longer than wide with distinct frontal area delimited by distinct constriction ( Fig. 6A ). Trunk distinctly wider than cephalothorax, divided into anterior and posterior parts by shallow transverse furrow: anterior part (second and third pedigerous somites) with weakly convex lateral margins; posterior part (fourth pedigerous somite) with pair of small flattened lobes located dorsally above bases of fourth legs: dorsal lobes lamellate, clearly separated in midline ( Fig. 6A ). Urosome comprising fifth pedigerous somite, genital complex and 1-segmented abdomen, all fused. Caudal rami paired, each ramus about 2.1 times longer than wide; with bluntly rounded apex. Parabasal flagellum cylindrical with swollen base. Leg 3 comprising small fleshy lamella located posteriorly on third pedigerous somite; each leg projecting ventrally ( Fig. 6B ), concave posteriorly and about one quarter width of trunk. Leg 4 bilobate; inner and outer lobes elongate, subequal ( Fig. 6 A–B). Leg 5 absent. Body length of ♀ ranging from 4.56 to 5.00 mm, with a mean of 4.68 mm (based on 10 specimens).

Male body comprising cephalothorax and trunk ( Fig. 6 C–D). Cephalothorax comprising 40% of total body length; with distinct frontal area bearing antennules and antennae delimited by constriction. Trunk comprising second to fourth pedigerous somites plus urosome, all somites fused but with grooves delimiting anterior pedigerous somites. Leg 3 uniramous, forming elongate, laterally-directed cylindrical lobe. Leg 4 biramous with subequal endopodal and exopodal lobes, each with rounded tip. Body length of ♂ ranging from 3.35 to 3.60 mm, with a mean of 3.47 mm (based on 5 specimens).

Distribution: This species was originally described from Japan ( Shishido, 1898) but it has a wide geographical range across the Indo-West Pacific with reports from Yemen ( Bassett-Smith, 1898a), India ( Pillai, 1964, 1985; Raja et al., 2018), Sri Lanka ( Kirtisinghe, 1964), Taiwan ( Ho et al., 2008), and China ( Song & Chen, 1976). Kabata (1979a) reported L. mugilii from Heron Island (Queensland) based on collections made by P.C. Young in 1963: the hosts in Australian waters were given as Mugil cephalus and a labrid, Choerodon cyanopodus (Richardson, 1843) (as Choerodon albigena (De Vis)) . The latter report, from a non-mugilid host, is very unusual and may indicate an error in labelling the original collection. Lernanthropus mugilii has been reported from a second mugilid, Planiliza haematocheila (Temminck & Schlegel, 1845) (as Mugil soiuy Basilewsky ) caught in Chinese and Japanese waters ( Song & Chen, 1976; Gusev, 1951). Australian material in the collections of the NHM, London was collected from M. cephalus caught at three sites in New South Wales by K. Rohde.

Remarks: Kabata (1979a) reviewed the nomenclature of this species concluding that Lernanthropus shishidoi Shiino, 1955 was an unnecessary replacement name for L. mugilii , and that Lernanthropus nudus Bassett-Smith, 1898 was a junior synonym. After examination of the holotype female of L. nudus stored in the collections of the Natural History Museum (BMNH Reg. No. 1898.12.2.12), we can confirm this synonymy. Yamaguti (1936) considered the name mugilii of Shishido (1898) to be a “ lapsus calami or a typographical error” and proposed to correct the name to L. mugilis . This is an unnecessary emendation. A detailed redescription of both sexes was provided by Ho & Do (1985). Ho et al. (2008) reported this species from Mugil cephalus landed in Taiwan and also redescribed both sexes. Izawa (2014) recently provided another re-description based on Japanese material from the same host.

This copepod can be very abundant locally: Raja et al. (2018) found a prevalence rate of 98% of L. mugilii on Mugil cephalus caught off the coast of southeastern India.

Figures

FIGURE 6. Lernanthropsis mugilii (Shishido, 1898), adult ♀. A, habitus, dorsal; B, habitus, ventral. Adult ♂. C, habitus, dor- sal; D, habitus, ventral. Scale bars 2 mm.