Diarthopodella prima Gómez 2021, sp. nov.
Creators: name: Gómez, Samuel
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Hexanauplia
Harpacticoida
Miraciidae
Diarthopodella
Diarthopodella prima

description: Diarthopodella prima sp. nov.
(Figs. 31–35)
urn:lsid:zoobank.org:act: 5B42B0DD-57F1-4B3F-96B2-5B93800F4FB1
Type locality. Guaymas Basin, between San Pedro Nolasco Island and Tortuga Island, Gulf of California, Mexico; Talud X cruise, sampling station 15 (27.7°N, 111.6333°W); depth 1,570 m; organic carbon content, 4.48%; organic matter content, 8.37%; sand, 4.49%; clay, 11.96%; silt, 84 %.
Other locality. Off Sinaloa State, east of Pescadero Trough, Gulf of California, Mexico; Talud IV cruise, sampling station 19 (24.26667°N, 108.4019°W); depth, 1,240 m; organic carbon content, 3.96%; sand, 1.77%; clay, 49.12%; silt, 49.12 %.
Specimens examined. From the type locality. Adult female holotype dissected and mounted onto ten slides (EMUCOP-110207-05); February 11, 2007; coll. S. Gómez.
From other localities. Copepodite CV paratype dissected and mounted onto six slides (EMUCOP-250800-02); August 25, 2000; coll. S. Gómez.
Etymology. The specific epithet from the Latin prima, first, makes reference to the first species attributed to the new genus. It is in the nominative singular. Gender feminine.
Description of female. Total body length measured from tip of rostrum to posterior margin of caudal rami, 660 µm; habitus pyriform, widest at posterior end of cephalothorax, tapering posteriad (Fig. 31A); cephalothorax/body length ratio, 0.3.
Prosome and pedigerous somites (Fig. 31A) largely as in previous species.
Urosome (Fig. 31A, D) consisting of fifth pedigerous somite (first urosomite), genital double-somite (genital— second urosomite—and third urosomite fused), two free urosomites, and anal somite. Urosomites without expansions laterally nor dorsally; integument weakly sclerotized.
Fifth pedigerous somite (Fig. 31A) narrower than preceding somites, with some sensilla dorsally, without spinular ornamentation.
Second and third urosomites completely fused dorsally and ventrally forming genital double-somite (Fig. 31D), with dorsolateral trace of division (Fig. 31A); genital double-somite 1.2 times as long as wide, widest part measured in proximal third close to P6; proximal half with few dorsal sensilla and with two dorsolateral sets of spinules (Fig. 31A), ventrally without sensilla nor spinules (Fig. 31D); distal half with dorsolateral sensilla and spinular rows (Fig. 31A), ventrally with few sensilla and without spinules (Fig. 31D); posterior hyaline fringe broad and smooth; genital complex hardly distinguishable, copulatory pores not exposed, paired genital apertures located ventrolaterally and covered by P6 (Fig. 31D).
Fourth urosomite (Figs. 24A, 25A–B) as distal half of genital double-somite; no pores detected.
Fifth urosomite as previous somite but without sensilla (Fig. 31A, D); no pores detected.
Anal somite about twice as wide as long (Fig. 31A), with spinules around joint of caudal rami (Figs. 31A, D), medial cleft with ventral spinules as shown (Fig. 31D), with one dorsolateral pore on each side (Fig. 31A); anal operculum without spinular ornamentation, semicircular, flanked by one sensillum on each side (Fig. 31A).
Caudal rami elongate, about 4.4 times as long as wide (Fig. 31A, D) and slightly longer than fifth and anal somites combined, outer and inner margins nearly straight, with outer spinules at base of setae I and II, III, V, and VII (Fig. 31A–E); with seven elements (Fig. 31B, C, E); setae I and II situated more proximally than in the previous species, in distal third, lateral, seta I setiform and ventral to seta II, the latter long; seta III subdistal, arising at distal sixth, ventrolateral (Fig. 31B, C,. E; detached during dissection in Fig. 31C–D); setae IV and seta V distal, rat-tail like in distal half, with fracture plane; seta VI small, issuing at inner distal corner; dorsal seta VII triarticulate at base, aligned with seta III, arising close to inner margin.
Rostrum (Fig. 31A) trapezoidal, elongate, not fused to cephalothorax, bifid, with two subdistal sensilla, without dorsal pore.
Antennule (Fig. 32A) eight-segmented, all segments smooth; first segment without pore. All setae smooth; only one seta with fracture plane detected on third segment; seventh segment with one, eighth segment with four articulated setae. Armature formula: 1(1); 2(10); 3(8); 4(6 + (1 + ae)), 5(3); 6(3); 7(4); 8(5 + acro). Acrothek consisting of two setae and one minute aesthetasc fused basally.
Antenna (Fig. 32B). Coxa short, with some outer spinules. Allobasis as long as free endopodal segment, with spinules midway inner margin, with one abexopodal seta arising slightly above the middle of inner margin. Free endopodal segment elongate; proximal half with longitudinal row of strong inner spinules, distal half with subdistal outer strong spinules, with two outer subdistal frills; armature composed of two spines and two setae laterally, distally with one inner apical spine, three apical geniculate setae and one slender element, and one outer distal pinnate element fused basally to slender seta. Exopod three-segmented; first and third segments longest; first and middle segments without, third segment with spinules as shown; first and second segments with one distal seta each, third segment with one proximal and three apical setae, two of which seemingly fused basally.
Mandible (Fig. 33A). Coxa relatively short. Gnathobase wide; ventral distal corner produced into small sharp semi-hyaline process; with one strong and several smaller teeth, two spines and two setae, of which one pinnate. Basis elongate, spinular ornamentation as shown, with three subdistal outer setae. Exopod arising from short pedestal, one-segmented, elongate, about 3.5 times as long as wide, and 0.4 times as long as basis; with three lateral and three apical setae, none of which fused basally. Endopod recurved, twisted over exopod; laterally with two proximal subequal setae and one subdistal comparatively longer element, distally with four distal elements, of which longest fused to endopod basally and with hyaline flange in middle part.
Maxillule (Fig. 33B). Arthrite of praecoxa with two surface setae and few dorsal spinules; distal armature composed of seven elements as shown, one medial small seta, and one lateral pinnate recurved seta. Coxal endite with three setae and with apical spinules. Basis with two endites; proximal endite seemingly with three, distal endite seemingly with two slender setae. Exopod and endopod fused basally, separated from basis, one-segmented; endopod larger than exopod, with four setae; exopod with two setae.
Maxilla (Fig. 33C–E). Large syncoxa with outer spinules as shown; with three endites; proximal endite bilobed, proximal lobe with one, distal lobe with two setae; middle and distal endites elongate, the latter slightly longer, with three spinulose setae each (Fig. 33E). Basis drawn out into strong claw, with strong spine and two slender setae, one of which arising from elongate setophore (Fig. 33D). Endopod one-segmented, with six slender setae (one arising basally, one medially, and four apically).
Maxilliped (Fig. 33F) presumably subchelate, endopod lost during dissection. Syncoxa slightly longer than wide, visibly longer than basis; seemingly without spinular ornamentation; with one bare and two spinulose strong elements, of which bare seta and one spinulose element at the same level, the other arising distally from pedestal. Basis shorter than syncoxa; rectangular; with some outer spinules; with one anterior and one posterior inner spinular row as figured; with two slender distal setae.
P1 (Fig. 34A). Intercoxal sclerite (not shown) transversely elongate, nearly straight, without surface ornamentation. Coxa massive, 1.4 times as wide as long, with outer and medial spinules as shown. Basis with spinules at base of outer and inner spines and between rami, with spinules midway inner margin. Exopod twosegmented, visibly shorter than endopod, reaching proximal third of ENP2; segments without outer nor inner acute distal processes; no pores detected on exopodal segments; EXP1 and EXP2 subequal in length; both segments with outer spinules as depicted; EXP1 without inner seta, EXP2 with five elements, of which outermost spine probably homologous to the outer spine of the second exopodal segment of other species of the subfamily, and two innermost setae short, setulose and rat-tail like in distal half. Endopod two-segmented, visibly longer than exopod; segments without outer nor inner acute distal processes; no pores detected on endopodal segments; ENP1 reaching proximal fourth of EXP2, 2.3 times as long as wide, and 0.7 times as long as ENP2, with few inner long spinules and with longitudinal outer and apical spinules as shown, with inner seta; ENP2 elongate, visibly longer than ENP1, six times as long as wide, inner proximal margin with few slender spinules, with longitudinal rows of outer spinules, with one inner seta issuing at proximal third, one inner apical slender seta, one medial apical pinnate element, and one outer apical spine.
P2 (Fig. 34B). Intercoxal sclerite (not shown) not transversely elongate, trapezoidal, with strong pointed process on distal outer corners, without surface ornamentation. Coxa with outer spinules proximally and medial minute spinules subdistally. Basis with strong acute inner process, with much smaller process between rami, with inner long and selender spinules, with outer seta. Exopod three-segmented, reaching slightly below middle of ENP3; first and third segments longest; EXP1 and EXP2 with outer acute distal process, with outer and distal spinules, and with distal inner frill as shown, distal processes of EXP3 as shown; EXP1 without, EXP2 with subdistal outer pore; EXP1 and EXP2 with one inner seta; EXP3 seemingly without spinular ornamentation, with two inner setae, two apical elements and three outer spines. Endopod three-segmented, longer than exopod; ENP1 shortest, about 0.7 times as long as ENP2; ENP2 and ENP3 subequal in length; all endopodal segments with longitudinal row of outer spinules; ENP1 and ENP2 with outer and inner acute distal processes, but outer process of ENP2 remarkably longer, both segments with apical minute spinules, distal processes of ENP3 as shown; ENP3 with subdistal medial pore; ENP1 with one, ENP2 with two inner setae; ENP3 with one inner seta, two apical elements and one outer spine.
P3 (Fig. 35A). Intercoxal sclerite (not shown) as in P2. Coxa as in P2 but with additional subdistal outer spinular row, seemingly without medial minute spinules subdistally. Basis as in P2 but with exceedingly long outer seta. Exopod three-segmented, shorter than endopod, reaching distal fourth of ENP; EXP1 and EXP2 as in P2, but will less developed outer distal processes and with ninner setules; EXP3 with distal processes as shown, with few outer proximal spinules, with subdistal pore, with three inner setae, of which distalmost thicker, two apical elements, and three outer spines. Endopod largely as in P2, except for inner seta of ENP1 long as stiff, and armature complement of ENP2 (with one instead of two inner setae) and ENP3 (with three instead of one inner seta).
P4 (Fig. 35B). Intercoxal sclerite (not shown), coxa and basis largely as in P3, except for shorter outer seta of basis. Exopod visibly longer than endopod; EXP1 and EXP2 with outer acute distal process less developed than in P3, of EXP3 as shown; EXP1 and EXP2 without, EXP3 with subdistal pore; ornamentation and armature complement as in P3. Endopod three-segmented, shorter than exopod, reaching middle of EXP3; outer distal processes of endopodal segments largely as in P3 except for less developed outer process of P4 ENP2; spinular ornamentation as in P3; ENP3 with subdistal inner pore; ENP1 and ENP2 as in P3, but with longer inner elements; ENP3 with two inner, two apical and one outer spine.
Setal formula of swimming legs as follows:
P5 (Fig. 32C). Baseoendopod pentagonal; endopodal lobe poorly-developed, with four setae, of which two outermost and adjacent two setae smooth and set close together, innermost seta separated by wide gap and pinnate. Exopod oval, with some outer spinules, with five setae, of which outer and distal outer setae pinnate, others smooth (innermost medial seta lost during dissection).
P6 (Fig. 31D) represented by a minute flap covering ventrolateral genital aperture, fused to somite, without surface ornamentation, with one slender seta.
Male. Unknown.
Variability. No variability was detected in the single female found in the sediment samples.
description: Published as part of Gómez, Samuel, 2021, On some deep-sea Stenheliinae from the Gulf of California and the west coast of the Baja California Peninsula (Mexico): the genus Delavalia Brady, 1869 and proposal of Archaeohuysia gen. nov. and Diarthropodella gen. nov. (Copepoda Harpacticoida: Miraciidae), pp. 171-235 in Zootaxa 5051 (1) on pages 214-221, DOI: 10.11646/zootaxa.5051.1.12, http://zenodo.org/record/5563569