Microcyclops anceps anceps (Richard, 1897)

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 : 43-44

Taxon classification Animalia Cyclopoida Cyclopidae

Microcyclops anceps anceps (Richard, 1897) Figures 15, 16, 17

Description of female.

Dorsal posterior margin of second prosomal somite with crenulated hyaline fringe (Fig. 15A, B), posterior margin of fourth prosomal somite wrinkled (Fig. 15B). Caudal surface of antennal basis with three oblique rows of tiny spinules near inner margin and two basal (proximal) rows of long spinules near outer margin (Fig. 15C, D, F). Antenna with three-segmented endopod bearing 1, 9, and 7 setae, respectively. Frontal surface of antennal basis with three rows of spinules: one proximal oblique, one near lateral (outer) margin in middle of segment, and one next to exopod seta (Fig. 15E). Mandible with nine teeth on gnathobase (Fig. 15G). Maxillular palp with two armed and one naked setae apically; one armed seta plus two nude setae on lateral lobe, proximal seta with tiny spinules (Fig. 15H). Distal coxal endite of maxilla with two long setae: proximal seta with two long, basal setules and bifurcated apically; distal seta armed with a continuous row of tiny spinules along one (inner) margin (Fig. 15I). Basipodite with claw-like projection bearing two stout teeth followed by a row of tiny spinules, and one long smooth seta on its base; two-segmented Enp bearing 2 and 3 setae, respectively (Fig. 15I). Maxilliped with a row of spinules in syncoxa, Bsp, and Enp1, on frontal view (Fig. 15J).

Inner margin of basipodite with long and fine hairs in P1−P3 (Fig. 16A, B). One pore present on lateral margin of Enp2P1. Spine absent on inner margin of BspP1 (Fig. 16A). Inner margin of BspP4 with long. Inner margin of BspP4 with long spinules (Fig. 16D). Intercoxal sclerites naked in P1 and P2 (Fig. 16A, B). Usually one distal row or sometimes two rows of spinules present on intercoxal sclerite of P3 (Fig. 16C). P4 sclerite with two rows of spinules (Fig. 16D): spinules in distal row larger and stronger than those in proximal row (Fig. 16D). Medial apical spine of Enp2P4 1.3 ± 0.1 times as long as lateral apical spine, and 0.7 ± 0.03 times as long as segment; length to width ratio of segment 2.5 ± 0.1.

Strong spinules present (Figs 16E, 17D) or absent (Fig. 17A) on fifth pediger near base of lateral seta of P5. This character shows both inter- and intrapopulation variation; in one population, the females do not have spinules next to lateral seta (MNHN-Cp7296, unfigured here), while the males of the same population do (Fig. 17E).

Free segment of fifth leg 2.5 ± 0.2 times longer than wide, with relatively large spinule in distal position (Figs 16E, 17A); free segment 0.4 ± 0.08 times as long as apical seta. Distal margin of anal somite with continuous row of strong spinules on ventral and dorsal surfaces (Figs 17B, F). Caudal ramus 3.7 ± 0.3 times longer than wide, inner margin naked. Spinules present at base of caudal seta III. Caudal seta II inserted at 71.1 ± 1.15% of caudal ramus length (Fig. 17B).

Seta VII and VI 0.5 ± 0.1 and 0.8 ± 0.1times as long as caudal ramus, respectively. Relative lengths of terminal caudal seta from outermost to innermost, 1.0: 4.9: 7.1: 1.3 (Fig. 17B). Caudal setae IV and V with homonomous setulation, with hair-like setules only (Fig. 17B).