Caligus belones Krøyer, 1863

Boxshall, Geoffrey A. & Bernot, James P., 2023, Resolving taxonomic and nomenclatural problems in the genus Caligus O. F. Müller, 1785 (Copepoda: Caligidae), Zootaxa 5360 (4), pp. 545-567 : 546-547

Caligus belones Krøyer, 1863

Material examined by R. F. Cressey: One female from Belone belone (Linnaeus, 1760) caught in the river Elbe, Germany and stored in the Smithsonian Institution , Washington D.C., USA (Reg. No. USNM 180596 ) .

Supplementary Description: Genital complex of female about 1.2 times longer than wide and about 2.3 times longer than abdomen; genital complex with rounded posterolateral lobes; abdomen about 1.4 times longer than wide, with lateral swellings anterior to midlevel ( Fig. 1A ). Caudal rami about 1.6 times longer than wide. Antenna ( Fig. 1B ) with irregularly tapering posterior process on proximal segment; subchela armed with 2 setae located proximally and near anterior margin. Postantennal process ( Fig. 1B ) with small base and weakly curved tine. Posterior process of maxillule ( Fig. 1B ) strongly tapering towards acute tip. Sternal furca with widely divergent tines ( Fig. 1C ). Second exopodal segment of leg 1 ( Fig. 1D ) armed with 3 plumose setae along posterior margin; distal margin spines 1 to 3 each with accessory process; seta 4 more than twice as long as spine 1 and longer than segment. Leg 2 ( Fig. 1E ) with outer margin of second endopodal segment ornamented with setule row; first and second exopodal segments armed with outer spines directed obliquely across surface of ramus; third segment armed with II, I, 5. First exopodal segment of leg 3 ( Fig. 1F ) lacking inner seta; armed with short, slightly curved, outer spine ornamented with narrow flange along lateral margin, spine not reaching articulation separating second and third segments. Leg 4 ( Fig. 1G ) with 2-segmented exopod armed with I, IV spines, each with conspicuous pecten at base.

Remarks: Caligus belones has a complicated history. It was first described by Krøyer (1863) based on females collected from Belone belone (as “Hornfisk”) caught in Denmark. Later Wilson (1905) provided a redescription of a species he identified as C. belones but unfortunately Wilson’s species has a 2-segmented exopod on leg 4 with a spine formula of I, III whereas Krøyer (1863: pl. VII, Fig. 1e ) shows the formula of C. belones as I, IV. The species described by Wilson (1905) was renamed C. wilsoni by Delamare Deboutteville & Nuñes-Ruivo (1958) in a paper which provided a partial redescription of true C. belones . Other partial descriptions are available (e.g. Cressey & Collette, 1970) but none provides the detail needed for the development of the online key.

Figures

FIGURE 1. Caligus belones Krøyer, 1863 adult female (body length 5.7 mm). A, habitus, dorsal; B, antenna, postantennal process and maxillule in situ, ventral; C, sternal furca; D, leg 1; E, leg 2; F, exopod of leg 3; G, exopod of leg 4.