Lepeophtheirus acutus Heegaard, 1943

Boxshall, Geoff, 2018, The sea lice (Copepoda: Caligidae) of Moreton Bay (Queensland, Australia), with descriptions of thirteen new species, Zootaxa 4398 (1), pp. 1-172 : 142-144

Lepeophtheirus acutus Heegaard, 1943

( Fig. 67 )

Material examined. 28♀♀ from Aetobatus ocellatus (Kuhl, 1823) (TC17287) 19 January 2016, QM Reg. No. W53122; 7♀♀, 1♀ immature, 2♂♂ (TC17294) 19 January 2016, QM Reg. No. W53123; 2♀♀ (TC17115) 13 January 2016, 1♀ (TC 17360) 21 January 2016, 6♀♀, 1 incomplete, 1♂ (TC17940) 6 July 2016, 1♀, 2♂, 1 immature (TC17932) 5 July 2016, 1♀, 1 immature, 1♂ (TC 1 7933) 5 July 2016; NHMUK Reg. Nos 2017.453– 462. 1♀ from Himantura cf. astra Last, Manjaji-Matsumoto & Pogonoski, 2008 (TC17750) 30 June 2016, NHMUK Reg. No. 2017.463.

Site on host. Body surface.

Differential diagnosis. Cephalothorax dorsoventrally flattened with well-developed marginal membranes along lateral zones of dorsal cephalothoracic shield; frontal plates lacking lunules. Genital complex subtriangular, about 1.5 times longer than wide ( Fig. 67A ); genital complex more than half length of cephalothorax; abdomen distinct, 1-segmented, about 1.4 times longer than wide; carrying caudal rami on posterior margin, either side of anal slit. Antenna with well-developed, pointed, posterior process on proximal segment. Tine of post-antennal process slightly curved; associated papillae multisensillate. Posterior tooth on anterior sclerite overlapping base of posterior process of maxillule ( Fig. 67B ). Sternal furca with straight, divergent, tapering tines. Distal exopodal segment of leg 1 with 3 plumose setae on posterior margin; distal margin spine 1 longest ( Fig. 67C ), spines 2 and 3 each with accessory process and ornamented with serrations; seta 4 just shorter than spine 3. Outer margin of first endopodal segment of leg 2 ornamented with row of stout teeth ( Fig. 67D ); second endopodal segment short with hirsute lateral margin. Leg 3 with 2-segmented exopod; first segment bearing strong outer spine and inner plumose seta; compound distal segment bearing total of 9 setal elements (4 spines and 5 setae); endopod 2-segmented; first segment forming short velum and bearing inner plumose seta; compound distal segment with 6 plumose setae. Leg 4 uniramous, 3-segmented ( Fig. 67E ); first and second exopodal segments armed with I and III spines, respectively; apical spine just longer than second segment, other 2 distal spines less than half length of apical spine. Leg 5 represented by outer papilla bearing protopodal seta and inner papilla bearing 3 plumose setae. Mean body length of adult female 4.20 mm, range 3.85 to 4.44 mm (based on 14 specimens). Mean body length of adult male 2.10 mm, range 2.04 to 2.19 mm (based on 4 specimens).

Remarks. This species was originally described by Heegaard (1943) based on a syntype series taken from Taeniura lymma (Forsskål, 1775) caught in the western Pacific off Abemama Atoll in Kiribati (formerly the Gilbert Islands). It was redescribed in detail by Tang et al. (2013) who also summarized existing records. The majority of published reports of L. acutus are based on specimens removed from diverse elasmobranchs kept in captivity including: Pteroplatytrygon violacea (Bonaparte, 1832) , Carcharhinus amblyrhynchos (Bleeker, 1856) , C. melanopterus (Quoy & Gaimard, 1824) and Stegostoma fasciatum (Hermann, 1783) in the Tropen-Aquarium Hagenbeck in Germany (Kik et al., 2011), Glaucostegus typus, Triaenodon obesus (Rüppell, 1837) and Stegostoma fasciatum in Burger’s Zoo, The Netherlands (Kik et al., 2011), and Manta alfredi (Kreft, 1868) and Rhincodon typus Smith, 1828 held in sea pens off Okinawa-jima Island, Japan ( Tang et al., 2013). There is also material in the collections of the Natural History Museum, London, collected from M. alfredi in the S.E.A. Aquarium, Singapore (NHMUK Reg No. 2015.567-572). In the wild, Lepeophtheirus acutus has also been reported on Rhinobatos rhinobatos (Linnaeus, 1758) and Aetomylaeus bovinus (Geoffroy Saint-Hilaire, 1817) in Turkish waters (Özak et al., in press.) and on Rhinobatos annulatus Müller & Henle, 1841 caught off Muizenberg Beach in South Africa (unpublished data). Rodríguez-Santiago et al. (2016) recorded L. acutus on the body surface of Aetobatus narinari (Euphrasen, 1790) caught in the southern Gulf of Mexico, off Campeche.

This is the first record of L. acutus from Moreton Bay and both the hosts, Aetobatus ocellatus and Himantura cf. astra, reported here are new host records. This wide-ranging copepod has not previously been reported from Australian waters.

Figures

FIGURE 67. Lepeophtheirus acutus Heegaard, 1943, female. A, habitus, dorsal; B, maxillule; C, distal margin spines on exopod of leg 1; D, first and second endopodal segment of leg 2; E, leg 4. Scale bars: 1.0 mm on A, 100 µm on B, D, 200 µm on E, 50 µm on C.