Cerviniopsis reducta, Park, Eun-Ok, Shimanaga, Motohiro, Yoon, Suk Hyun & Lee, Wonchoel, 2012

Park, Eun-Ok, Shimanaga, Motohiro, Yoon, Suk Hyun & Lee, Wonchoel, 2012, A new species of the genus Cerviniopsis from Sagami Bay, Japan and reinstatement of the genus Neocervinia, with a report on the male of Neocervinia itoi Lee & Yoo, 1998 (Copepoda: Harpacticoida: Aegisthidae), Zootaxa 3575, pp. 27-48 : 28-39

publication ID	https://doi.org/ 10.5281/zenodo.209382
DOI	https://doi.org/10.5281/zenodo.6175410
persistent identifier	https://treatment.plazi.org/id/D469FB21-4A0A-FF8A-FF1A-FC52FA3BFE6A
treatment provided by	Plazi
scientific name	Cerviniopsis reducta
status	sp. nov.

Treatment

Cerviniopsis reducta sp. nov.

( Figures 1–8 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 View FIGURE 8 )

Type locality. Sagami Bay, Japan (35° 04.4' N 139° 32.3' E). The water depth ranged from 750 to 770m.

Specimens examined. Holotype: male (CR00179981) dissected on seven slides. Paratypes: one female (CR0000179982) dissected on eight, and one male (CR00179983) on eight slides, respectively. All specimens are from the type locality and collected by Dr. M. Shimanaga on May 20 2002.

Description. Male. Total body length 967 µm (measured from tip of rostrum to posterior margin of caudal rami). Maximum width 211µm measured at posterior margin of cephalothorax. Body surface armed with sensilla and minute denticles ( Figs. 1 View FIGURE 1 A, C–D).

Prosome ( Fig. 1 View FIGURE 1 A) 5-segmented, comprising cephalosome and 4 free pedigerous somites. P1 bearing somite fused to cephalosome, but with surface suture line showing original segmentation. Cephalothorax smooth ( Fig. 1 View FIGURE 1 A), with few sensilla and smooth posterior margin. Short tripod shaped wrinkle present in middle of cephalosome. Succeeding two prosomites with thin comb-like hyaline frills forming smooth posterior margin.

Rostrum well developed, elongated and triangular-shaped with pointed anterior apex, clearly fused to cephalosome ( Fig. 1 View FIGURE 1 A–B). Dorsal surface smooth with 1 pair of sensilla near middle of lateral margin of rostrum dorsally and 1 tube pore on ventral surface.

Urosome ( Figs. 1 View FIGURE 1 A, C–D) 6-segmented, comprised of P5-bearing somite, 4 free abdominal and anal somites. Urosomites 3–5 denticulated dorsoventrally with well developed hyaline frill. P5 -bearing somites with smooth dorsoventaral surface and few spinules along lateral posterior angles.

Anal somite ( Fig. 1 View FIGURE 1 D) with well-developed operculum with spinulate posterior margin and flanked by pair of secretary pores.

Caudal rami ( Fig. 1 View FIGURE 1 A) ten times longer than wide; seta I shortest, located at proximal half; seta II 2.5 times longer than seta I, and located laterally; seta III as long as seta II; caudal setae IV pinnate, slightly longer than caudal ramus; caudal seta V pinnate, twice longer than IV; seta VI shorter than seta III and located on distal inner corner; seta VII bare, located near distal end of caudal ramus, as long as seta II, and triarticulated.

Antennule ( Fig. 2 View FIGURE 2 A) 7-segmented, segment 1 largest with several rows of spinules on surface. Segment 2 with few spinules on anterior surface. Aesthetascs on segments 2, 3, 4, and 7. Armature formula: 1-[1 pinnate], 2-[11 pinnate + 1 ae], 3-[3 bare + 3 pinnate + 1 ae], 4-[2 bare + 7 pinnate + (1+ae)], 5-[1 pinnate], 6-[2 pinnate], 7-[5 bare + 1 strong pinnate + 1 pinnate + 3 rigid spines + 1 acrothek]. Apical acrothek consisting of well-developed aesthetasc fused basally to 1 slender naked seta and 1 strong pinnate bent spine.

Antenna ( Fig. 2 View FIGURE 2 B) 3-segmented, comprising coxa, allobasis, and free 1-segmented endopod. Coxa with several rows of spinules. Allobasis with 2 plumose abexopodal setae. Exopod 4-segmented with seta formula 2.1.1.020, respectively; all setae pinnate; apical outermost seta strongest. Free endopodal segment with long spinules along surface, and with 1 naked seta and 2 pinnate spines laterally and 1 geniculate, and 5 pinnate setae and 1 strong pinnate spine apically.

Labrum ( Fig. 2 View FIGURE 2 C) well developed; ventral margin ornamented with blunt median tooth, several sub-lateral row of blunt teeth, and short lateral spinules.

Mandible ( Fig. 3 View FIGURE 3 A) with large coxa bearing well-developed gnathobase; cutting edge with 6 major blunt teeth overlapping each other; accessory seta plumose. Mandibular palp well developed. Basis set on peduncle, wider than long with 4 pinnate setae; 3 setae set on small peduncle, respectively; several rows of long spinules along anterior surface. Endopod 1-segmented with 3 plumose lateral, 2 naked and 5 pinnate apical setae; row of spinules along outer lateral margin. Exopod 4-segmented with seta formula 2.1.1.2; segment 1 largest, and long spinules on anterior surface.

Maxillule ( Fig. 3 View FIGURE 3 B) with rows of spinules along anterior suface and outer lateral margins as figured. Praecoxa with well developed arthrite bearing 2 plumose anterior surface setae and 9 apical setae and spines. Coxa with epipodite represented by 1 seta; endite cylindrical with 1 naked, and 5 pinnate setae. Basis and endopod completely fused forming maxillulary allobasis with 5 pinnate and 6 naked slender setae. Exopod also incorporated into maxillulary allobasis and represented by 3 plumose setae.

Maxilla ( Fig. 3 View FIGURE 3 C–D), syncoxa with row of spinules on outer lateral margin and cylindrical 4 endites (2 praecoxal, 2 coxal); enditic seta formula 5.3.3.3; proximal praecoxal endite largest with 2 pinnate and 3 naked setae; all setae on distal praecoxal and coxal endites naked. Allobasis produced into long curved claw; accessory armature consisting of 1 geniculate spine and 1 slender seta distally, 1 slender seta and 1 strong pinnate spine proximally near articulation with endopod. Endopod 3-segmented; enp-1 with 1 geniculate spiniform, and 1 slender setae; enp-2 with 2 geniculate spiniform setae; enp-3 with 1 geniculate spiniform and 2 naked slender setae.

Maxilliped ( Fig. 3 View FIGURE 3 E) comprising syncoxa, basis, and 2-segmented endopod; rows of spinules present anteriorly and posteriorly as figured. Syncoxa elongated with 5 strong pinnate spines and 1 pinnate seta. Basis with 1 pinnate seta and 1 strong pinnate spine. Endopod 2-segmented; proximal segment with 2 plumose setae; distal segment with 2 strong pinnate apical spines, and 2 lateral setae (proximal one plumose, distal one naked).

Swimming legs 1–4 ( Figs. 4 View FIGURE 4 A, B; 5A, B) biramous, P1–P4 with 3-segmented exopod and 3-segmented endopod, and each ramus ornamented with setules and spinules along inner and outer margins as illustrated. Intercoxal sclerites well developed; ornamented with row of spinules in middle of anterior and posterior surface.

P1 ( Fig. 4 View FIGURE 4 A), praecoxa with row of spinules on anterior surfaces. Coxa wider than long and trapezoidal, ornamented with row of spinules on anterior and posterior surface and along outer margin. Basis with 1 outer plumose seta and 1 inner strong uni-pinnate spine and ornamented with row of long spinules on anterior surface extending posteriorly. Endopod subequal to exopod in length; enp-3 longest. Exp-1 largest; median outer spine of exp-3 distinctly shorter than others.

P2 ( Fig. 4 View FIGURE 4 B), praecoxa, small with row of spinules along anterior distal margin. Coxa with row of spinules on anterior and posterior surface, and along outer margin. Basis with 1 short plumose outer seta and spinules on inner lateral margin and row of spinules along distal margin near articulation with exopod; ornamented with row of long spinules along inner lateral margin and posterior surface with small patch of spinules on anterior and posterior surface. Endopod not extending to distal end of exopod; row of fine spinules along outer margin of each segment; enp-1 with elongated outer distal end forming sharp triangular tip; enp-3 slightly longer than two preceding segments. Each exopodal segments with row of spinules along outer margins; exp-1 largest, and exp-2 shortest; inner apical seta of exp-3 reduced, naked and small.

P3 ( Fig. 5 View FIGURE 5 A), praecoxa, small with row of spinules along anterior median distal margin. Coxa with row of spinules on anterior and posterior surface and along outer margin. Basis with 1 plumose outer seta and long spinules on inner lateral margin and row of spinules along distal margin near articulation with endopod. Endopod exceeding to distal end of exopod; row of spinules along outer and inner margin of each segment; enp-1 and enp-2 with elongated outer distal end forming sharp triangular tip; enp-3 slightly longer than two preceding segments; inner apical seta on enp-3 reduced, naked, and small. Each exopodal segments with row of spinules and setules along outer and inner margins; exp-1 largest and exp-2 shortest; inner apical seta of exp-3 reduced, naked and small.

P4 ( Fig. 5 View FIGURE 5 B), praecoxa, naked. Coxa with row of spinules on anterior and posterior surface, and along outer margin. Basis with 1 plumose outer seta and long spinules on inner lateral margin and row of spinules along distal margin near articulation with endopod. Endopod exceeding to distal end of exopod; row of spinules along outer and inner margin of each segment; enp-1 and enp-2 with elongated outer distal end forming sharp triangular tip; enp-1 shortest; enp-3 longer than enp-2; inner apical seta on enp-3 reduced, naked and small. Each exopodal segments with row of spinules and setules along outer and inner margins; exp-1 shortest, and exp-3 longest; inner apical seta of exp-3 reduced, naked and small.

Armature formula as follows:

P5 ( Fig. 1 View FIGURE 1 F), baseoendopod forming short, outer setophore bearing plumose basal seta. Each endopodal lobe fused each other forming 1 narrow plate, without any ornamentation. Exopod long, narrow plate shaped, and 6.5 times longer than wide; whole surface covered with setules; with 1 strong pinnate apical, 1 short pinnate inner and 1 short naked outer lateral setae; outer lateral seta inserted at distal 1/3; 1 short spinous process present between apical and inner setae.

Sixth pair of legs ( Fig. 1 View FIGURE 1 E) not fused medially, symmetrical. Each P6 bilobate with outer lobe bearing elements consisting of 2 plumose setae; outer one shortest. Anterior surface naked and inner distal margin somewhat swollen without any ornamentation.

Female. Total body length of examined samples 1,219 µm, much larger than in male (measured from tip of rostrum o posterior margin of caudal rami). Largest width presumably at posterior margin of cephalic shield (not measurable due to dorsoventrally depressed body). General body appearance same as in male.

Rostrum ( Fig. 6 View FIGURE 6 C) well developed, elongated and triangular-shaped with pointed anterior apex, clearly fused to cephalosome. Dorsal surface smooth with 1 pair of sensillae near middle of lateral margin of rostrum dorsally and 1 tube pore on ventral surface as in male.

Urosome ( Fig. 6 View FIGURE 6 B) 5-segmented, comprised of P5-bearing somite, genital double, and 3 free abdominal somites. All urosomite with pattern of surface ornamentation consisting of small spinules dorsoventrally. Hyaline frills of urosomites denticulate.

Genital double somite ( Figs. 6 View FIGURE 6 B; 8C) with transverse surface ridge dorsally and laterally forming spinous processes laterally indicating original segmentation; completely fused ventrally. Genital field positioned anteriorly, just above middle line between original segmentation ( Fig. 6 View FIGURE 6 B); copulatory pore minute; gonopores fused medially forming single genital slit covered on both sides by well developed opercula derived from sixth legs; P6 elongate, with row of spinules along anterior and posterior margins, and 1 bare and 1 pinnate setae; outer seta longest and pinnate ( Fig. 8 View FIGURE 8 C).

Caudal rami ( Fig. 6 View FIGURE 6 B) 14 times longer than wide, longer than those in male and with 7 caudal setae as in male.

Antennule ( Fig. 6 View FIGURE 6 A) 7-segmented, segment 1 largest with several rows of spinules on surface. Segment 2 with few spinules on anterior surface. Aesthetascs on segments 3, and 7. Armature formula: 1-[1 pinnate], 2-[8 pinnate + 1], 3-[3 pinnate + 2 geniculate + 6 +(1+ ae)], 4-[3 pinnate], 5-[1 + 1 pinnate], 6-[1 + pinnate], 7-[1 strong pinnate + 2 + 3 rigid spines + 1 acrothek]. Apical acrothek consisting of well-developed aesthetasc fused basally to 1 slender pinnate seta and 1 strong pinnate bent spine.

Antenna, mandible, maxllule, maxilla, maxilliped, and P1 same as those in male.

Swimming legs 2–4 ( Figs. 7 View FIGURE 7 A–B, 8A) biramous, P2–P4 with 3-segmented exopod and 3-segmented endopod, and each ramus ornamented with setules and spinules along inner and outer margins as illustrated. Intercoxal sclerites well developed; ornamented with row of spinules in middle of anterior and posterior surface. Armature formula same as in male.

P2 ( Fig. 7 View FIGURE 7 A) endopod not extending to distal end of exopod; inner apical seta of exp-3 not reduced, long and pinnate.

P3 ( Fig. 7 View FIGURE 7 B) endopod not extending to distal end of exopod; inner apical seta on enp-3 not reduced, long, and pinnate. Inner apical seta of exp-3 not reduced, longer than outer apical one and pinnate.

P4 ( Fig. 8 View FIGURE 8 A), endopod nearly extending to distal end of exopod; inner apical seta on enp-3 not reduced, longer than outer apical one, and pinnate. Inner apical seta of exp-3 not reduced, longer than outer apical one and pinnate.

P5 ( Fig. 8 View FIGURE 8 B), baseoendopod forming short, outer setophore bearing naked basal seta. Each endopodal lobe fused each other forming 1 narrow plate, without any ornamentation except for 2 pores near articulation area with exopod. Exopod long, narrow plate shaped and about 6.5 times longer than wide; whole surface covered with setules; with 1 strong pinnate apical, 1 short naked inner and 2 naked outer lateral setae; distal outer lateral seta about 4 times longer than proximal outer lateral one; 1 pore present near proximal area of apical seta.

Etymology. The specific name, ‘ reducta ’ refers to the inner apical seta on the exp-3 of P2–P4, the outer apical seta of the enp-3 of P3 and the inner apical seta of enp-3 of P4 which are reduced strongly in the male of C. reducta .