Lernanthropus latis Yamaguti, 1954

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 : 54

Lernanthropus latis Yamaguti, 1954

( Fig. 24G )

Syn: Lernanthropus latesi Tripathi, 1962

Material examined: 7♀♀ from gills of Lates calcarifer (Bloch, 1790) , Darwin , Northern Territory; collected by B.K. Diggles, MAGNT Reg. No. Cr 019242 . 10♀♀ from gills of L. calcarifer, Darwin , Northern Territory; 11 October 2012, collected by B.K. Diggles , 5♀♀ QM Reg. No. W29492 , 5♀♀ NHMUK Reg.No. 2018.263–267 .

Differential diagnosis: Cephalothorax small relative to trunk, tapering towards frontal margin: trunk wider than cephalothorax with constriction in anterior part marking boundary between second and third pedigerous somites; posterior part (fourth pedigerous somite) comprising narrow anterior section immediately posterior to origin of laterally-directed third legs and dorsal trunk plate ( Fig. 24G ). Dorsal trunk plate almost circular, with strongly convex lateral and posterior margins. Urosome comprising fifth pedigerous somite, genital complex and abdomen, all fused. Paired caudal rami elongate, each ramus more than 3 times longer than width as base; tapering towards apex, fully concealed beneath dorsal trunk plate. Parabasal flagellum comprising swollen base and curved distal part; more than half length of antennule. Antenna slender, with strong hook-like process on medial margin of proximal segment. Leg 3 located on lateral surface of somite, forming rounded fleshy lamella, directed posterolaterally: third legs entirely separate. Leg 4 bilobate; inner lobe longer than outer, both protruding well beyond free posterior margin of dorsal plate. Fifth leg forming small laterally-directed process with rounded apex. Mean body length of ♀ 7.26, range 6.9 to 7.6 mm (based on 7 specimens); mean body length of ♂ 1.86 mm (data from Brazenor & Hutson, 2013).

Distribution: This distinctive species was originally described from Lates calcarifer caught off Macassar (Sulawesi) by Yamaguti (1954). It has since been reported from the same host taken at Chilka Lake and off Kerala in India ( Tripathi, 1962; Pillai, 1985), Sri Lanka ( Kirtisinghe, 1964), Thailand ( Ho & Kim, 2004) and Malaysia ( Chu et al., 2012). It was first reported from Australia on the same host kept in seacages at Port Hurd, Northern Territory ( Small et al., 2009).

Remarks: Lernanthropus latis is widely distributed and can be abundant locally: Raja et al. (2018) found a prevalence of 76.5% on L. calcarifer caught off the coast of southeastern India. This species has also been reported from cage cultured Lates calcarifer in Malaysia ( Abdul Khalid & Shaharoum-Harrison, 2014). Brazenor & Hutson (2013) considered L. latis to be a major threat to sustained mariculture of barramundi ( L. calcarifer ). They described the life cycle stages and examined the impact of water temperature and salinity on hatching success of the copepod. The overall prevalence of L. latis on wild L. calcarifer (n = 121) sampled from Darwin Harbour over 5 half yearly sampling periods between August 2012 and March 2014 ranged between 18.3% and 71.6% (mean intensity 1.0 –4.17 copepods per fish), with no apparent seasonality.

Figures

FIGURE 24. Lernanthropus gnathanodontus sp. nov., paratype ♂. A, tip of maxilla; B, maxilliped; C, leg 1 and intercoxal sclerite; D, leg 2; E, exopod of leg 2, anterior view; F, endopod of leg 3, showing surface ornamentation. Lernanthropus latis Yamaguti, 1954, adult ♀. G, habitus, dorsal. Scale bars A, C–F, 50 μm, B, 100 μm, G 1 mm.