Eurycletodes paraephippiger, Gomez, Samuel, 2018

Gomez, Samuel, 2018, New species of Eurycletodes Sars, 1909 and Odiliacletodes Soyer, 1964 from the deep Gulf of California (Copepoda, Harpacticoida, Argestidae), ZooKeys 764, pp. 1-25 : 2

Eurycletodes paraephippiger sp. n.

Material examined.

One female holotype (ICML-EMUCOP-020207-01) dissected on eight slides; collected on February 2, 2007.

Type locality.

Southern Trough of Guaymas Basin, Gulf of California, Mexico, 27°09'08"N, 111°39'57"W, depth 1440 m.

Description of female.

Habitus (Figs 1A, 2A) cylindrical, without clear distinction between prosome and urosome. Total body length, 831 µm, measured from tip of rostrum to posterior margin of caudal rami.

Rostrum well-developed (Fig. 1A, B), fused to cephalothorax, triangular, with pointed tip flanked by apical sensilla on each side.

Cephalothorax and free thoracic somites with reticulated pattern along postero-lateral margin, posterior margin coarsely denticulated dorsally and laterally, denticles increasing in size posteriorly (Figs 1A, 2A); with sensilla and tube pores issuing from conspicuous tubercles.

Urosomites with coarsely denticulated posterior margin dorsally and laterally, denticles increasing in size posteriorly (Figs 1A, 2A), much more developed than those of prosomites. Second and third urosomites distinct dorsally and laterally, posterior margin of anterior half of genital-double somite with denticulated posterior margin dorsally (Figs 1A, 2A), fused ventrally forming genital-double somite (Fig. 3A), with reticulated pattern along posterior margin dorsally and laterally, ventral reticulated pattern interrupted medially; posterior margin of second half of genital-double somite and fourth urosomite poorly developed ventrally, of fourth urosomite comparatively coarser and with reticulated pattern as in preceding somite (Fig. 3A); posterior margin of fifth urosomite with well-developed denticles dorsally and ventrally, coarser than in preceding somites, with continuous reticulated pattern along entire posterior margin (Fig. 3A), with dorsal (Fig. 1A) and lateral (Fig. 2A) sensilla and ventral tube-pores (Fig. 3A).

Anal somite nearly as long as three preceding somites combined, almost square from dorsal and lateral view, seemingly without spinular ornamentation dorsally and laterally (Figs 1A, 2A), ventrally cleft medially and with four proximal transverse rows of spinules (Fig. 3A); laterally (Fig. 2A, B) and ventrally (Fig. 3A) with posterior and inner margin, respectively, coarsely denticulated, and with minute spinules close to joint with caudal rami; anal operculum (Fig. 1A, C) coarsely denticulated, associated surface ornamentation seemingly two pores somewhat displaced anteriorly (seemingly without sensilla, probably broken off during dissection).

Caudal rami semi-cylindrical, about 1.6 times as long as broad from dorsal view (Fig. 1C), and about 2 times as long as broad from ventral view (Fig. 3A, B); ventrally with some minute spinules and one tube pore subdistally (the latter arrowed in Figs 1C, 2B, 3B); with seven setae as follows: seta I small, ventral and anterior to seta II, the latter about 3 times as long as the former; seta III arising from small protrusion, situated ventrally close to inner margin; setae IV and V longest; seta VI arising at inner distal corner, as long as seta I; dorsal seta VII tri-articulated, issuing from median dorsal process.

Antennule (Fig. 4A). Hexa-segmented; first segment small; second segment longest; surface of segments smooth except for spinular row on first segment; fifth segment with two well-developed bipinnate setae and a modified small element (see insert in Fig. 4A); last segment with five bi-articulated setae, one subapical well-developed seta, and acrothek, the latter consisting of one aesthetasc and two setae fused basally. Armature formula as follows: 1(0); 2(7); 3(4+[1+ae]); 4(1); 5(3); 6(8+[acro]).

Antenna (Fig. 4B). Allobasis ornamented with inner spinules as shown; without abexopodal seta. Exopod represented by single seta. Free endopodal segment with longitudinal spinular row along inner proximal margin, and with some subdistal spinules; with two lateral, bare, inner spines (proximal one clearly longer), and five distal elements (two spines, and two geniculate elements, of which outermost fused to one small seta basally).

Mandible (Fig. 5A). Coxa with some proximal spinules. Gnathobase formed by four tooth-like projections, and with a lateral small seta. Palp bi-segmented; first (basal) segment with spinules as shown, without basal seta, with one outer (exopodal) seta; second (endopodal) segment without surface ornamentation, with four bare setae, two of which fused basally.

Maxillule (Fig. 5B). Praecoxa with some proximal spinules; arthrite with six distal spines, one lateral and two surface setae. Coxal endite with three setae, one of which very strong and pinnate. Basis with some spinules, armed with one bare and one pinnate seta. Without endopod. Exopod represented by one pinnate seta.

Maxilla (Fig. 5C). Syncoxa with outer spinules, with two endites; proximal endite small, with one slender seta; distal endite with two slender setae and one strong spinulose element. Allobasis with some slender spinules, drawn out into strong pinnate claw, with two slender bare setae, one of which small and issuing from claw proximally, and a strong spinulose spine. Endopod uni-segmented, small, with two pinnate seta.

Maxilliped (Fig. 5D). Subchelate. Syncoxa with inner and outer tuft of slender spinules, with two setae. Basis with longitudinal outer spinules, unarmed. Endopod uni-segmented, fused to long, slender, pinnate claw.

P1 (Fig. 6A). Coxa with spinules as shown. Basis with outer and inner seta, the former stronger, with spinules at base of outer seta and at base of endopod. Exopod and endopod subequal in length. Exopod tri-segmented; segments with outer and apical spinules as shown; first and third segment subequal in length, second segment half as long as first segment; first segment without, second segment with one inner seta, third segment with two apical and three outer setae/spines. Endopod bi-segmented; first segment about 1.5 times as long as wide, with longitudinal row of outer, fine spinules, with one inner seta; second segment elongate, with one inner, two apical and one outer element, of which outer a spine.

P2-P4 (Figs 6B, 7A, B). Praecoxa presumably as in P2, with row of distal spinules. Coxa presumably as in P2 and P3, with one median, proximal row of minute spinules on anterior face, and long spinules close to outer margin on anterior and posterior face. Basis more or less triangular in shape with slender, long spinules along inner margin, with small spinules at base of endopod, of P2 without, of P3 and P4 with spinules at base of outer element; outer element spine-like in P2, a long, well-developed seta in P3 and P4. Exopod tri-segmented; first and third segment elongate, third segment slightly longer; second segment small, as long as broad; segments with inner slender, and outer strong spinules as shown; first segment with irregular outer margin; first and second segments with one inner seta; third segment of P2 and P3 with two inner well-developed setae, two apical setae and three outer spines, of P4 with two inner elements, of which proximal reduced and spine-like, two apical setae and three outer spines. Endopod bi-segmented; of P2 and P3 reaching insertion of proximal inner seta of EXP3, of P4 barely beyond apical margin of EXP2; first segment small, 1.5 times as long as wide, with one inner seta; second segment elongate, of P2 and P3 with five (two inner and two apical setae, and one outer spine), of P4 with four setae/spines (one inner and two apical setae, and one outer spine.

Armature formula of P1-P4 as follows:

P5 (Fig. 3C). Baseoendopod and exopod distinct. Baseoendopod with outer basal seta on short setophore, endopodal lobe with three setae, of which median longest. Exopod large, foliose, ovate, with reticulated surface, about 2 times as long as wide, with five setae, with slender spinules along inner and outer margin, and between setae, except between inner most and adjacent element.

P6 (Fig. 3A). Very reduced, each leg represented by two small setae; genital field located medially, with one aperture.

Male unknown.

Etymology.

The specific epithet and the Latin suffix pār, similar, refers to the resemblance between the new species and E. ephippiger Por, 1964. Gender masculine.