Caligus aesopus Wilson, 1921

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 : 37

publication ID

https://doi.org/ 10.11646/zootaxa.4398.1.1

publication LSID

lsid:zoobank.org:pub:79E3EB78-D1C3-45CF-AB13-F8E61C936252

DOI

https://doi.org/10.5281/zenodo.5952144

persistent identifier

https://treatment.plazi.org/id/03B587F2-AA49-4D0C-B6F8-FF7C3AE9F861

treatment provided by

Plazi

scientific name

Caligus aesopus Wilson, 1921
status

 

Caligus aesopus Wilson, 1921

( Fig. 15 View FIGURE15 )

Material examined. 2♀♀, 1♂ from Seriola hippos Günther, 1876 (TC18352) 28 March 2017, 1♀, 1♂ QM Reg.No. W53053; 1♀ NHMUK Reg. No. 2017.212.

Site on host. Unknown.

Differential diagnosis. Cephalothorax dorsoventrally flattened with well-developed marginal membranes along lateral zones; frontal plates with lunules; thoracic zone very small, extending posteriorly about level with posterior ends of lateral zones ( Fig. 15A View FIGURE15 ). Genital complex about 1.5 to 1.6 times longer than wide; abdomen indistinctly 2-segmented, with constriction at about posterior third; genital complex about 2 times longer than abdomen ( Fig. 15A View FIGURE15 ). Antenna with rounded posterior process on proximal segment ( Fig. 15B View FIGURE15 ). Post-antennal process bifid, main tine straight; associated papillae multisensillate. Posterior process of maxillule bifid; main (inner) tine much larger than outer. Maxilliped of female with rounded process proximally ( Fig. 15C View FIGURE15 ). Sternal furca with broad gape; tines incurved with rounded tips. Sympod of leg 1 ornamented with spinules and bearing rounded process anteriorly on ventral surface (arrowed in Fig. 15D View FIGURE15 ); vestigial endopod elongate with 2 setal vestiges apically: distal exopodal segment with 3 plumose setae on posterior margin; distal spine 1 longer than other spines; spines 2 and 3 with accessory processes; seta 4 longer than spine 1 and about as long as segment. Leg 2 with marginal setules on endopodal segments 2 and 3; outer spine on exopodal segment 1 lying obliquely across segment 2, spine on segment 2 aligned close to longitudinal axis of ramus. Leg 3 ( Fig. 15E View FIGURE15 ) apron with raised rib, with bluntly rounded tip, plus circular array of large denticles on ventral surface and corrugated adhesion pad near outer margin on dorsal surface; exopod indistinctly 3-segmented, first segment with large recurved outer spine, lacking inner seta; second and third segments incompletely separated, outer margins hirsute, with multiple rows of long setules: endopod 2-segmented, first endopodal segment forming velum and bearing inner seta; distal segment with partial suture, armed with total of 6 plumose setae. Leg 4 uniramous, 4-segmented; exopodal segments ( Fig. 15F View FIGURE15 ) with I; I; III spines; innermost spine distinctly longer than middle spine. Body lengths of adult females 4.54 and 4.79 mm; length of adult male 3.46 mm.

Remarks. Caligus aesopus was first described from off the Juan Fernandez Islands in the East Pacific and the host was given as probably Seriola peruana Steindachner, 1881 ( Wilson, 1921) . Hewitt (1963) subsequently reported C. aesopus from Seriola lalandi Valenciennes, 1833 (as Seriola grandis Castelnau ) caught off New Zealand. However, C. aesopus has been confused with a very similar species, C. spinosus Yamaguti (1939) , which was originally described by Yamaguti (1939) based on material from Seriola quinqueradiata Temminck & Schlegel, 1845 caught off Japan. Unfortunately, Yamaguti did not compare his new species with C. aesopus . Caligus spinosus was recognised as a junior subjective synonym of C. aesopus by Fernandez & Villalba (1986) and this synonymy was followed by Lin & Ho (2007). However, Choe & Kim (2010) recently found two Caligus species on species of Seriola Cuvier, 1816 in Korean waters. They provided full descriptions of both sexes of both species, and they reinstated C. spinosus as a valid species, distinct from C. aesopus . Caligus aesopus can be distinguished by the presence of a constriction subdividing the female abdomen into a wider anterior part (two thirds) and a narrower posterior part (one third), by the large size and lower number (less than 15) denticles present in a rosette on the apron of leg 3, and by the apical spine on the distal exopodal segment of leg 4 being distinctly longer than the adjacent middle spine. Choe & Kim (2010) listed a few other minor character differences for the females, such as the presence of an anterior process on the surface of the sympod of leg1 ( Fig. 15D View FIGURE15 ), and documented a difference in the form of the myxal processes on the male maxilliped.

Caligus aesopus was found on S. lalandi in Korean View in CoL waters (Choe & Kim, 2010) and it can be found on the same host from South Africa (Kensley & Grindley, 1973) to New Zealand (Hewitt, 1963). In addition, it occurs on S. dumerili (Risso, 1810) View in CoL in Taiwan ( Lin & Ho, 2007) and on “probably S. peruana View in CoL ” in the eastern Pacific ( Wilson, 1921). Choe & Kim (2010) concluded that the material from Sphyraena obtusata View in CoL caught off India and described by Pillai (1963) could be attributed to C. aesopus , but possible confusion with C. abigailae sp. nov. described above from this host should also be considered. Choe & Kim (2010) demonstrated that the material redescribed and illustrated by Shiino (1960) as “ C. spinosus ” should be attributed to C. aesopus . The host in Moreton Bay, S. hippos View in CoL , is a new host record for C. aesopus .

Caligus spinosus has previously been reported from Australian waters (e.g. Rohde, 1978, Byrnes, 1986, Hutson et al., 2007a, b) but there is uncertainty over these identifications since during at least some of the period covered by these reports, the two species were considered to be synonyms.

Kingdom

Animalia

Phylum

Arthropoda

Class

Maxillopoda

Order

Siphonostomatoida

Family

Caligidae

Genus

Caligus

Loc

Caligus aesopus Wilson, 1921

Boxshall, Geoff 2018
2018
Loc

C. abigailae

Boxshall 2018
2018
Loc

C. spinosus

Yamaguti 1939
1939
Loc

Caligus spinosus

Yamaguti 1939
1939
Loc

Caligus aesopus

Wilson 1921
1921
Loc

C. aesopus

Wilson 1921
1921
Loc

C. aesopus

Wilson 1921
1921
Loc

C. aesopus

Wilson 1921
1921
Loc

S. peruana

Steindachner 1881
1881
Loc

S. hippos

Gunther 1876
1876
Loc

Sphyraena obtusata

Cuvier 1829
1829
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