Caligus engraulidis Barnard, 1948

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 : 548-549

Caligus engraulidis Barnard, 1948

Material examined by R. F. Cressey: Holotype female from Stolephorus holodon (Boulenger, 1900) (as Engraulis (Anchoviella) holodon ) caught in the Zwartkops river, Algoa Bay, Republic of South Africa, loaned to R. F. Cressey by the Iziko South African Museum (Reg. No. A6520).

Supplementary Description: Caudal rami ( Fig. 2A ) about twice as long as wide, ornamented with short setules along medial margin and armed with 6 setae as typical for genus. Antenna ( Fig. 2B ) with spatulate process on posterior margin of proximal segment and armed with short seta proximally on subchela. Postantennal process ( Fig. 2B ) strongly curved and ornamented with bisensillate papillae. Maxillule ( Fig. 2B ) with simple tapering posterior process. Sternal furca ( Fig. 2C ) with very broad, blunt-tipped and slightly divergent tines. Leg 1 ( Fig. 2D ) lacking spinular ornamentation on surface of protopod but bearing single sensilla close to outer protopodal seta; distal exopodal segment armed with 3 plumose setae on posterior margin; distal margin with spines 1 to 3 all subsimilar in length and all lacking accessory process, seta 4 shorter than spines. Leg 2 ( Fig. 2E ) with setular ornamentation on outer margin of endopodal segment 2 extending slightly over onto surface of segment; outer spine on first exopodal segment large, aligned more closely with outer margin rather than positioned obliquely across ramus; third exopodal segment apparently with II, I, 4 setal formula. First exopodal segment of leg 3 ( Fig. 2F ) lacking inner seta, armed with short outer spine and with outer margin produced into additional spinous process. Leg 4 ( Fig. 2G ) 2-segmented, comprising protopodal segment bearing outer plumose seta and compound exopodal segment armed with naked spine near middle of outer margin and 3 spines on distal margin—1 long inner terminal spine ornamented bilaterally with strong denticles, shorter middle spine ornamented with setules bilaterally, and very short naked outer spine.

Remarks: The original description by Barnard (1948) was ultra-brief and was supported only by a sketch of the female genital complex and abdomen, plus the sternal furca and details of the 2 spines he observed on the apex of leg 4. Although no habitus drawing was possible due to damage to the holotype, the re-examination reveals important details of the structure and armature of the antennae, maxillules, sternal furca, legs 1 to 4 and caudal rami. The most significant of these are: the lack of accessory processes on spines 2 and 3 of the distal exopodal segment of leg 1, the presence of an additional spinous process on the outer margin of the first exopodal segment of leg 3, and the 1-segmented state of the exopod of leg 4 which is armed with 1 outer spine and 3 apical spines. Barnard’s (1948) original description referred to the presence of only 2 apical spines on the exopod and the segmentation of this taxonomically important limb was depicted inaccurately.

Figures

FIGURE 2. Caligus engraulidis Barnard, 1948 adult female (body length 3.5 mm). A, caudal ramus; B, antenna, postantennal process and maxillule in situ, ventral; C, sternal furca; D, leg 1; E, leg 2 (with some setae missing on endopod); F, first and second exopodal segments of leg 3; G, leg 4.