Caligus ilhoikimi, Suárez-Morales, Eduardo & Gasca, Rebeca, 2016

Suárez-Morales, Eduardo & Gasca, Rebeca, 2016, A new species of Caligus Müller, 1785 (Copepoda: Siphonostomatoida: Caligidae) from coral reef plankton in the Mexican Caribbean, Zootaxa 4174 (1), pp. 424-436 : 425-431

publication ID	https://doi.org/ 10.11646/zootaxa.4174.1.26
publication LSID	lsid:zoobank.org:pub:F8E96588-D64D-4895-9A99-289158BFF0A7
DOI	https://doi.org/10.5281/zenodo.6067027
persistent identifier	https://treatment.plazi.org/id/03C7EE21-FFC5-FFE8-2EF1-FBF1FB601C35
treatment provided by	Plazi
scientific name	Caligus ilhoikimi
status	sp. nov.

Treatment

Caligus ilhoikimi sp. nov.

( Figs. 1–4 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 )

Material examined. Holotype female, plankton light trap, collected March 11, 2005 by L. Vásquez-Yeomans, Xcalak reef zone, Quintana Roo, Mexico. Specimen partially dissected, mounted in glycerine, semi-permanent slides sealed with Entellan (ECO-CHZ-09268) . Allotype male, same date, collector, and site, partially dissected, semi-permanent slides (ECO-CHZ-09269). Paratypes 12 adult females from same locality, collector and date, specimens undissected, ethanol-preserved (ECO-CHZ-09270) ; 10 adult males, undissected, ethanol-preserved (ECO-CHZ-09271). Three adult females, 3 adult males mounted in semi-permanent slides, same collection data (USNM-1267302).

Type locality. Xcalak reef area, eastern coast of the Yucatan Peninsula, Mexican Caribbean , 18°20’00” N, 87°48’48” W. GoogleMaps

Host. Unknown, plankton collection.

Description of female. Body shape as shown in Fig. 1 View FIGURE 1 A, with cephalic shield broadly ellipsoidal with curved lateral margins. Total length of holotype 3.75 mm, size range 3.37–4.21 mm (average = 3.77 mm, n = 15) measured from the anteriormost margin of the cephalothorax to the posterior margin of the abdomen. Greatest width 1.86–1.95 mm (measured at widest part of cephalothorax) (excluding narrow marginal hyaline membrane: 0.07 mm). Cephalothorax comprises more than half (62%) of total length. Genital complex about as long as wide, with rounded outer margins; posterolateral region weakly protruding posteriorly. Abdomen subrectangular, about 1.3 times as long as wide, genital complex approximately 1.4 times longer than abdomen ( Fig. 2 View FIGURE 2 F). Caudal rami subrectangular about 1.2 times longer than wide, armed with 3 long terminal, one small outer, one small inner pinnate setae and short dorsal seta ( Fig. 2 View FIGURE 2 F). Lunules widely separated, spaced by the length of about 4.6 times lunule diameter.

Antennule ( Fig. 1 View FIGURE 1 B) with usual structure found in Caligus , 2-segmented, proximal segment distinctly longer than distal segment, armed with 23 plumose setae. Distal segment bearing 11 setal elements (1 of them subdistal, inserted medially on inner margin) plus two aesthetascs. Sternal furca ( Fig. 1 View FIGURE 1 C) tines broad, with straight inner and outer margins and distally wide, truncate margins.

Antenna ( Fig. 1 View FIGURE 1 D) claw recurved at right angle near tip with small, proximal accessory seta; posterior process heavily sclerotized, pointed, moderately sharp. Postantennary process ( Fig. 1 View FIGURE 1 E) broad, sickle-shaped, with rounded tip, with two basal papillae, each armed with single short seta, adjacent papilla located nearby on sternum smaller, also with single short seta.

Mouth cone as in genus, with slender mandibles bearing row of 15–20 teeth ( Fig. 1 View FIGURE 1 H). Maxillule represented by pointed subtriangular process and basal papilla bearing two subequally long setae ( Fig. 1 View FIGURE 1 F). Maxilla ( Figs. 1 View FIGURE 1 G) 2-segmented, slender, brachiform; proximal segment (lacertus) unarmed; distal segment (brachium) slender, with subdistal flabellum on outer margin. Terminal elements, calamus and canna unequally long, the latter about 0.75 times as long as former. Maxilliped ( Fig. 2 View FIGURE 2 A) robust, without protrusions on basal region; subchela about 0.5 times as long as basal segment. Shaft with short subdistal seta. Terminal claw heavily sclerotized, shorter than shaft, armed with short proximal seta on inner margin.

Leg 1 ( Fig. 2 View FIGURE 2 B, C) coxa with proximal inner seta and short subdistal seta on outer margin. Mammiliform papilla on distal inner position of segment. First exopodal segment with inner margin bearing row of short hair-like elements and short outer subdistal spiniform seta. Last exopodal segment bearing 3 medial unequally long pinnate setae and 4 smooth terminal spines, without accessory processes, innermost element being longest, two outer elements equally long and fourth one, on medial position, being shortest ( Fig. 2 View FIGURE 2 C).

Leg 2 ( Fig. 2 View FIGURE 2 D, E) coxa subquadrate, armed with long plumose coxal seta on inner margin. Basipodite robust, with small seta on outer distal edge and setule-bearing papilla on middle inner margin. First exopodal segment bearing strong outer spine reaching across second segment to proximal margin of third segment; second segment with much shorter recurved outer spine reaching to middle of last exopodal segment. Distal segment with two elements on outer margin, one short naked spiniform element plus stout sclerotized spine. Terminal spine curved, with narrow membrane along outer margin, about 2.3 times as long as subdistal spine and 1.5 times as long as distal segment ( Fig. 2 View FIGURE 2 E). All setae on medial margins of all segments pinnate.

Leg 3 ( Fig. 3 View FIGURE 3 A, B) exopod first segment with stout, slightly recurved terminal spine with thin flange on outer lateral margin nearly reaching to third segment; three outer distal setae digitiform, subequally long ( Fig. 3 View FIGURE 3 B). First endopodal segment with single inner pinnate seta, second segment with 6 pinnate setae.

Leg 4 ( Fig. 3 View FIGURE 3 C) uniramous, brachiform; exopod 2-segmented. Protopod with short seta on distal outer margin. First exopodal segment with terminal spine not reaching base of setal elements of second segment. Second exopodal segment bearing 3 smooth, unequally long spines, outermost shortest, innermost longest; each of 4 exopodal spines with subtriangular pecten at base.

Armature of rami of legs 1–4 as follows (Roman numerals indicating spines and Arabic numerals setae): Leg 5 represented by two small papillae on posterolateral corner of genital complex, one armed with two short pinnate setae, the other with one seta ( Fig. 2 View FIGURE 2 F).

Description of male. Body ( Fig. 3 View FIGURE 3 D) smaller than female, length excluding caudal rami: 2.93–3.41 mm, average = 3.15 mm, n = 15. Cephalothoracic shield broadly ovoid in shape, 1.73 ± 0.13 mm long and 1.65 ± 0.12 mm wide (excluding narrow marginal hyaline membranes: 0.06 mm). Frontal plates well developed, carrying moderately large lunules separated by 2.1 times diameter of lunule; free margin of thoracic zone projecting well beyond tips of lateral zones; sinuses wide, moderately deep. Fourth pediger separated from genital complex by weak suture, somite roughly hexagonal in shape, about 2.5 times wider than it is long. Genital complex roughly oblong. Abdomen narrower and shorter than genital complex, subrectangular, represented by two somites; proximal somite wider than long, anal somite distinctly longer than wide. Caudal ramus subrectangular, 1.6 times longer than it is wide, bearing 6 setal elements including 3 terminal setae, one short inner setulated seta, one short outer naked seta plus short dorsal seta. Inner margin pilose ( Fig. 4 View FIGURE 4 H).

Antennule as in female.

Antenna ( Fig. 3 View FIGURE 3 E, F) 3-segmented, robust; proximal segment strong, with large corrugated pad on medial surface, second segment about as long as first one, armed with 3 corrugated pads, 2 on distal inner margin, 1 subdistal on outer surface; terminal segment smallest, armed with single basal seta and with three short, strong overlapping hooks ( Fig. 3 View FIGURE 3 F).

Sternal furca as in female, tines slightly more separated basally and more divergent ( Fig. 3 View FIGURE 3 G). Postantennary process as in female except for being more strongly curved, with longer setae on basal papillae and adjacent papilla armed with two long setae ( Fig. 3 View FIGURE 3 H).

Maxillule ( Fig. 3 View FIGURE 3 H) shorter and stronger than in female, comprising distally blunt dentiform process bearing basal papilla armed with two unequally long setae, one of them articulate.

Maxilla ( Fig. 4 View FIGURE 4 A, B) as in female except for brachium bearing subterminal hyaline spiniform element; canna about half as long as calamus, the latter terminally branched forming a spiral-like ornamentation ( Fig. 4 View FIGURE 4 B).

Maxilliped ( Fig. 3 View FIGURE 3 I) robust, subchela about 0.5 times as long as basal segment. Basal segment with medial sinus. Shaft with short subdistal seta. Terminal claw heavily sclerotized, shorter than shaft, armed with short proximal seta on inner margin.

Leg 1 ( Fig. 4 View FIGURE 4 C) as in female except for having three outer setal elements equally long, instead of medial one being shorter.

Leg 2 ( Fig. 4 View FIGURE 4 D) as in female including short lateral spine (asterisk in Fig. 4 View FIGURE 4 D) and papilla-like elements near insertion of inner setae (arrowed in Fig. 4 View FIGURE 4 D).

Legs 3 and 4 as in female ( Fig. 4 View FIGURE 4 E, F).

Leg 5 ( Fig. 4 View FIGURE 4 G) located on middle of lateral margin of genital complex, represented by two short segments, one (proximalmost) armed with short pinnate seta and the other, larger segment with two short, pinnate setae. Leg 6 ( Fig. 4 View FIGURE 4 G) represented by lateral protuberance armed with two setae, inner seta twice as long as outer seta.

Etymology. The new species is named after Prof. Il-Hoi Kim, Gangneung-Wonju National University, Korea, for his abundant and high-quality contributions to the knowledge of symbiotic copepods worldwide.