Caligus enormis Wilson 1913
Creators: name: Boxshall, Geoff A
name: El-Rashidy, Hoda H.
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Maxillopoda
Siphonostomatoida
Caligidae
Caligus
Caligus enormis

description: Caligus enormis Wilson, 1913   
 Differential diagnosis: Female genital complex and abdomen combined slightly longer than cephalothorax; body length 2.15 mm. Male body length 1.6 mm. Female genital complex large, with parallel sides, rounded corners and narrow waist-like region anteriorly; without distinct postero-lateral lobes, fused to extremely short unsegmented abdomen. Male genital complex elongate; free abdomen 1-segmented, about 1.5 times longer than wide. Post-antennal process sexually dimorphic, much larger and more strongly curved in male. No additional process present between post-antennal process and base of antenna in female. Sternal furca lacking. Female maxilliped with smooth medial margin. Male maxilliped with large pointed process on myxal margin, opposing tip of claw, and smaller rounded process located more distally on medial margin. Exopod of leg 1 lacking spine at anterodistal angle; seta at inner distal angle about as long as segment; one short spinulate seta present on posterior margin. Outer margin of second endopodal segment of leg 2 ornamented with fine setules. Leg 4 with strongly produced outer margin on first exopodal segment; outer and middle spines on distal margin markedly shorter than terminal spine.   
 Material examined: none   
 Distribution: Jamaica.   
 Hosts: Scaridae: Sparisoma viride (Bonnaterre, 1788).   
 Remarks: Despite its name, this is a small species with a female body length of about 2.15 mm. It is the large size of the post-antennal process in the male that gives this species its name (Wilson 1913).   
 Caligus enormis is an atypical member of the productus -group which can be distinguished from all other members of the group by the extremely short abdomen of the female that appears fused to the genital complex. In addition it lacks a sternal furca, as confirmed by Ho & Bashirullah (1977), and lacks the anteriormost of the terminal spines on the distal exopodal segment of leg 1 (Ho & Bashirullah 1977: Fig. 5 C) while retaining one posterior margin seta, albeit spinulate rather than plumose. These are unusual characters. With reference to leg 3, Wilson (1913) stated “the endopod contains but one partial joint, which is fused to the basal plate”. This joint carries an inner plumose seta (Wilson 1913: Fig. 121). The type material of C. enormis was re-studied by Ho & Bashirullah (1977) but was not in good condition and they provided no further information on leg 3, but they commented that C. enormis was “not a species of Caligus ” as it lacks an endopod in leg 3. The partial loss of the endopod of leg 3, even if it is not based on an aberrant or damaged individual, might merely be an autapomorphy of the species. It cannot be inferred from this one reduced character state, that C. enormis should be placed in a different genus. We retain this species within the productus -group, with which it shares important apomorphies including the segmentation and armature of leg 4, and the sexual dimorphism of the post-antennal processes.
description: Published as part of Boxshall, Geoff A & El-Rashidy, Hoda H., 2009, A review of the Caligus productus species group, with the description of a new species, new synonymies and supplementary descriptions, pp. 1-26 in Zootaxa 2271 on page 12, DOI: 10.5281/zenodo.190952