Microcyclops ceibaensis (Marsh, 1919)

Gutierrez-Aguirre, Martha Angelica & Cervantes-Martinez, Adrian, 2016, Taxonomic evaluation of eleven species of Microcyclops Claus, 1893 (Copepoda, Cyclopoida) and description of Microcyclopsinarmatus sp. n. from America, ZooKeys 603, pp. 33-69 : 40-41

Taxon classification Animalia Cyclopoida Cyclopidae

Microcyclops ceibaensis (Marsh, 1919) Figures 9, 10, 11

Description of female.

Antennule 12-segmented (Fig. 9A). Antenna with 3-segmented endopod with 1, 9, and 7 setae, respectively (Fig. 9F). Frontal surface of antennal basis with one basal row of spinules arranged in arc next to medial (inner) margin, and one median row of spinules next to lateral (outer) margin. (Fig. 9D, E). Caudal surface of antennal basis with two basal rows of spinules arranged in arc, plus two rows of long spinules on outer margin (Fig. 9F). Labrum with 7 marginal teeth between two lateral curved teeth, and two rows of long spinules (6) overhanging distal margin (Fig. 9B, C). Gnathobase of the mandible with eight teeth (Fig. 9G). Maxillular palp with three apical setae, three setae on lateral lobe, and one proximal seta. The proximal seta armed on both margins, one seta on lateral lobe and one apical seta with setules (Fig. 9H). Distal coxal endite of the maxilla with two long setae: the proximal seta with two long basal spinules and bifurcated apically, distal seta smooth (Fig. 9I). Basipodite with one claw-like projection bearing thin spinules on concave margin, and one long smooth seta on its base. One-segmented Enp bearing 5 setae (Fig. 9I). Maxilliped with syncoxa (2 setae), basis (2 setae), and two-segmented Enp bearing 1 and 3 setae, respectively. Ornamentation of setae on syncoxa and Enp1 variable (intrapopulation variation, arrowed in Fig. 9J). Syncoxa and basis of maxilliped with a row of spinules on caudal surface next to lateral margin (Fig. 9J).

Dorsal margin of prosomal somites slightly serrated (Fig. 10A). Basis of P1−P3 with pilose inner margin. Intercoxal sclerites of P1-P3 with one row of short spinules (Fig. 10B-G), in some populations the sclerite of P3 with two rows of spinules (Fig. 10H). Enp2P1 with two pores on lateral margin (Fig. 10C). Because of the condition of the specimen in slide USNM-222299, it was not possible to verify the presence of spinules on the sclerite as well as the pores on the second endopodal segment of P1 (Fig. 10B).

P1 basis with long medial spine reaching distal third of Enp2P1. Spine ornamented with long setules near base and with short spinule-like setules more distally (Fig. 10B, C). Inner margin of P4 basis with strong spinules. Intercoxal sclerite rectangular, and ornamented with two rows of spinules (Fig. 10I, K). Enp2P4 2.2 ± 0.1 times as long as wide; medial spine 1.5 ± 0.1 times as long as the lateral spine, and 0.6 ± 0.06 times as long as segment (Fig. 10J, K). Sixth leg with one long seta plus two short spines (Fig. 10L).

Fifth pediger nude (Fig. 11A). Urosomal somites with serrated hyaline fringes (Fig. 11B, C). Fifth leg with one cylindrical free segment 3.8 ± 1.4 times as long as wide; tiny spinule present on inner margin. P5 free segment 0.3 ± 0.1 times the length of the distal seta (Fig. 11C). Distal margin of anal somite with a continuous row of strong spinules on ventral and dorsal surfaces (Fig. 11B, C). Caudal ramus 3.6 ± 0.4 times longer than wide, inner margin naked. Spinules present at base of caudal setae II and III; seta II inserted at 69 ± 3.2% of the caudal ramus (Fig. 11C).

Seta VII 0.7 ± 0.1 times as long as caudal ramus, seta VI 0.8 ± 0.1 times as long as caudal ramus. Relative lengths of terminal caudal seta from outermost caudal seta to innermost caudal seta: 1.0: 5.7: 9.5: 1.8 (Fig. 11C, D). Seta IV and seta V with homonomous setulation, with long and fine setules at whole length (Fig. 11D); inner median terminal caudal seta (V) with interrupted row of setules along the proximal, lateral margin (Fig. 11E, F).