The genus Caligus Müller, 1785 (Copepoda: Siphonostomatoida): two new species from reef associated fishes in New Caledonia, and some nomenclatural problems resolved Author Hayes, Polly Author Justine, Jean-Lou Author Boxshall, Geoffrey A. text Zootaxa 2012 3534 21 39 journal article 10.5281/zenodo.210824 4a3ca8ca-49ff-4de5-99fb-53dca97cd62c 1175-5326 210824 Caligus macoloricola sp. nov. Type material: Holotype female, partly dissected in alcohol, MNHN-IU- 2009-2254 , and 4 paratype females (1 intact female paratype MNHN-IU- 2009-2255 , 2 intact and 1 incomplete female paratypes BMNH 2012.244-246): all collected on 16 January 2006 by J.-L. Justine from gills of a single specimen of Macolor niger [JNC 1716B – Fork Length 560 mm , Weight 3200 gm]. Type locality: Passe de Dumbéa, New Caledonia . Type Host: Macolor niger (Forsskål, 1775) Microhabitat on host: gills Etymology: the species name is based on the generic name of the host Macolor and - icola meaning inhabitant. Holotype adult female ( Fig. 4 A) body length including caudal rami 3.54 mm ; paratypes ranging from 3.52 to 3.64 mm ; female mean body length 3.58 mm (based on 4 specimens ). Egg strings uniseriate, 2.11 to 2.20 mm long, each containing 26– 33 eggs. Cephalothorax subcircular with marked posterior sinuses; just wider than long (1.97 x 1.90 mm ) and comprising about 54% of total body length. Free margin of thoracic portion of dorsal cephalothoracic shield extending posterior to rear margins of lateral portions. Genital complex about 1.5 times wider than long (1.46 x 0.99 mm ); with strongly convex, rounded lateral margins and no trace of posterolateral lobes ( Fig. 4 A). Abdomen 1-segmented; as long as wide (0.44 x 0.44 mm ); carrying paired caudal rami on slightly oblique distal margin; anal slit terminal. Caudal rami ( Fig. 4 B) with parallel sides, 1.05 times longer than wide, measured at midpoints of margins ( Fig. 1 B). Each ramus armed with short hirsute seta at inner distal angle, slightly longer hirsute seta at outer distal angle, minute hirsute seta located just ventral to outer distal seta, and 3 setae on distal margin (2 long and plumose; middle seta reduced, non-plumose). Inner margin of ramus naked. Antennule ( Fig. 4 C) 2-segmented; large proximal segment with 25 plumose setae along anteroventral margin and 2 setae located dorsally; distal segment bearing 13 elements (12 setae plus 1 aesthetasc) around apex, plus isolated seta on posterior margin. Antenna (a2) ( Fig. 4 D) comprising proximal segment with posteriorly-directed narrow, tapering, spinous process; middle segment subrectangular, tapering slightly distally, unarmed; terminal segment forming strong, recurved claw armed with slender seta on anterior margin. Post-antennal process (pap) ( Fig. 4 D) vestigial, with short, blunt process; ornamented with 2 tiny sensillae on basal part and with similar bifid sensilla on adjacent ventral cephalic surface. Mandible ( Fig. 4 E) of typical stylet-like structure, with 12 marginal teeth. Maxillule (mxl) ( Fig. 4 D) comprising anterior papilla bearing 3 unequal, naked setae and simple, posterior, tine-like process. Maxilla 2- segmented ( Fig. 4 F), comprising elongate syncoxa and basis: syncoxa unarmed; basis bearing subapical flabellum on anterior margin, terminating in 2 unequal claw-like elements (calamus and canna). Calamus about twice as long as canna, both ornamented with strips of serrated membrane arranged obliquely along surface. Maxilliped subchelate ( Fig. 4 G); large proximal segment unarmed; distal subchela with apical claw separated from proximal segmental part by incomplete suture; segmental part armed with 1 seta. Sternal furca ( Fig. 4 H) with long, slightly divergent tines, each with bluntly rounded tip. First swimming leg ( Fig. 5 A) with unarmed coxa; coxae of leg pair joined by slender intercoxal sclerite (interpodal bar); basis with inner and outer plumose setae; exopod 2-segmented; endopod represented by unarmed process on posterior margin of basis. Exopod directed laterally and forming main axis of leg; first segment robust, about 2.8 times longer than wide and armed with small outer (anterior) spine; second segment armed with 3 long plumose setae along posterior margin and 4 distal elements ( Fig. 5 A). Distal elements as follows: spine 1 (anteriormost) well developed, simple, longer than spines 2 and 3; latter each with accessory process; seta 4 about twice as long as spine 1, and about equal in length to segment. Second leg ( Fig. 5 B) biramous, with flattened protopodal segments and 3-segmented rami. Coxae of leg pair joined by narrow, plate-like, intercoxal sclerite bearing marginal membrane posteriorly. Coxa with plumose seta and surface sensilla. Basis armed with outer naked seta; ornamented with surface sensilla, marginal membrane posteriorly, and membrane anteriorly reflexed over dorsal surface of segment. Exopodal segments 1 and 2 each with large reflexed outer spines extending obliquely across ventral surface of ramus; segment 3 with 2 outer spines (proximal-most spine minute; distal spine with bilateral membrane), apical spine with marginal membrane laterally and pinnules medially, and 5 inner plumose setae. Endopodal segments 1 and 2 armed with 1 and 2 inner plumose setae respectively; segment 3 with 6 plumose setae; outer margins of first and second endopodal segments ornamented with fine setules. Third leg pair ( Fig. 5 C) forming flattened plate closing posterior part of cephalothoracic sucker as typical for genus. Leg pair joined by narrow, plate-like, intercoxal sclerite (apron) bearing marginal membrane posteriorly. Protopodal part flattened, bearing inner plumose seta at junction with intercoxal plate, and outer plumose seta near base of exopod; sensilla located adjacent to inner coxal seta; ornamented with membrane along posterior margin medial to endopod and along lateral margin anterior to exopod; space between rami covered by flap-like velum ornamented with row of short setules along free margin. Exopod 3-segmented; first segment with large, weakly curved, outer claw directed over ventral surface of ramus; second segment with slender outer spine and inner plumose seta; third with 7 setal elements (3 outer spiniform elements and 4 inner plumose setae). Endopod 2- segmented; first segment with inner plumose seta; second with 6 setal elements increasing in length from outermost to innermost. FIGURE 4. Caligus macoloricola sp. nov. , holotype female. A. body, dorsal view; B. caudal ramus, dorsal view; C. antennule; D. antenna, post-antennal process and maxillule, in situ , ventral view; E. mandible; F. maxilla; G. maxilliped; H. sternal furca. Scale-bars : A = 1 mm, B–E, H = 100 μm, F = 200 μm, G = 400 μm. FIGURE 5. Caligus macoloricola sp. nov. , holotype female. A. leg 1, ventral view; B. leg 2, ventral view; C. leg 3, ventral view; D. leg 4; E. Leg 5, in situ . Scale-bars : A = 100 μm, B–D = 200 μm, E = 50 μm. Fourth leg ( Fig. 5 D) 3-segmented, comprising large protopodal segment and 2-segmented exopod with exopodal segments separated by oblique articulation: protopodal segment armed with outer seta; first exopodal segment with outer spine with pecten at base; second segment armed with 3 unequal naked spines along distal margin and outer margin spine, each with pecten at base ( Fig. 5 D). Fifth leg located posterolaterally on genital complex, represented by outer protopodal seta originating on somite surface and 2 setae on small inner papilla representing exopod ( Fig. 5 E). Sixth leg represented by unarmed plate closing off genital opening. Remarks: There are only 5 species of Caligus characterised by the possession of a 3-segmented fourth leg carrying 4 spines (three distal and one lateral) on the distal segment, in combination with a reduced or vestigial post-antennal process. These are C. afurcatus Wilson, 1913 , C. asymmetricus , C. dactylopteni Uma Devi & Shyamasundari, 1981 , C. enormis Wilson, 1913 and C. phipsoni Bassett-Smith, 1898 . Only one of these species, C. dactylopteni , shares a genital complex that is wider than long with the new species. The new species differs from C. dactylopteni in several characters: it lacks the large myxal process present on the female maxilliped of C. dactylopteni , and it differs in the arrangement of the setal elements on the distal margin of the second exopodal segment of leg 1. In C. dactylopteni spine 1 is small and located subdistally on the anterior margin, spines 2 and 3 lack accessory processes, and seta 4 is about the same length as spines 2 and 3. In contrast in the new species, spine 1 is located at the antero-distal corner of the segment and is larger than spines 2 and 3, both of which carry accessory processes, and seta 4 is much longer than the longest of the spines. These differences support the establishment of a new species to accommodate this material. This species was reported as an unnamed Caligus sp. nov. from the host Macolor niger in Justine et al. (2012) .