Nannopus parvus, Vakati, Vinod & Lee Wonchoel, 2017

Vakati, Vinod & Lee Wonchoel, 2017, Five new species of the genus Nannopus (Copepoda: Harpacticoida: Nannopodidae) from intertidal mudflats of the Korean West Coast (Yellow Sea), Zootaxa 4360 (1), pp. 1-66 : 31-41

publication ID	https://doi.org/ 10.11646/zootaxa.4360.1.1
publication LSID	lsid:zoobank.org:pub:D7ABA95B-5F41-42EB-94FA-1105489C5C34
DOI	https://doi.org/10.5281/zenodo.6024257
persistent identifier	https://treatment.plazi.org/id/8B0AA13A-FFBD-FFDC-A6C8-FDD3AA33FC89
treatment provided by	Plazi
scientific name	Nannopus parvus
status	sp. nov.

Treatment

Nannopus parvus sp. nov.

( Figs. 23–31 View FIGURE 23 View FIGURE 24 View FIGURE 25 View FIGURE26 View FIGURE 27 View FIGURE 29 View FIGURE 30 View FIGURE 31 )

Type locality. Intertidal mudflat, Yangdo-myeon , Ganghwa Island, South Korea, Yellow Sea, 37°40'08.4"N 126°24'20.9"E ( Fig. 1A, B View FIGURE 1 ). GoogleMaps

Type material. Holotype: 1 female adult in 70% ethanol (NIBRIV0000753986). Allotype: 1 male adult in 70% ethanol (NIBRIV0000810848). Paratypes: 3 females dissected on 6, 3 and 2 slides (NIBRIV0000810844 – 46), and 1 male dissected on 4 slides (NIBRIV0000810849); 3 females and 3 males together on SEM stub (NIBRIV0000810847). All samples were collected from the type locality by Vinod Vakati, 5 March 2015.

Etymology. The species epithet is derived from the Latin “ parvus ” referring to the small caudal seta V in both sexes.

Description of female (based on holotype and paratypes). Body fusiform ( Fig. 23A, B View FIGURE 23 ), total length ranged from 404 to 416 µm (mean = 428 µm, n = 4; holotype: 404 µm, measured from tip of rostrum to posterior margin of caudal rami). Maximum width ranged from 136 to 168 µm (mean = 151 µm, n = 4; holotype: 145 µm, measured at posterior margin of cephalothorax). Boundary between prosome and urosome clearly visible, urosome/prosome length ratio 0.7 and body length/width ratio about 2.7. Body ornamentation ( Fig. 23A, B View FIGURE 23 , 24A–D View FIGURE 24 , 26C View FIGURE26 , 27A, B View FIGURE 27 ) consisting of dorsal denticles, and 2 to 3 transverse rows of denticles in unique pattern. P2-bearing somite with 1 transverse row of frill anteriorly. Urosomites with horizontal row of setules ventrally ( Fig. 27A View FIGURE 27 ). Anal somite with 1 or 2 horizontal row of setules ( Figs. 23A View FIGURE 23 ). Cephalothorax ( Fig. 23A View FIGURE 23 ) bell shaped, almost as long as wide, comprising 35.4% of total body length, with few paired sensilla, and posterior margin serrated.

Rostrum ( Fig. 23B, C View FIGURE 23 ) triangular with round tip, with pair of dorsal sensilla, recurved downward as in N. minutus , and terminal margin densely hirsute.

Prosome ( Fig. 23A, B View FIGURE 23 ) 4-segmented, comprising cephalothorax and 3 subequal free pedigerous somites. P1- bearing somite fused to cephalothorax, pedigerous somites serrated, and row of sensilla posteriorly. P2-bearing somite with pair of very long sensilla.

Urosome ( Figs. 23A, B View FIGURE 23 , 26C View FIGURE26 ) 5-segmented, posteriorly tapering, comprising P5-bearing somite, genital double-somite, 2 free abdominal somites, and anal somite. Posterior margins serrated dorsally and ventrally. Each somite with row of sensilla along dorsal posterior margin except for penultimate somite, and row of spinules along ventral posterior margin.

Genital double somite ( Figs. 23B View FIGURE 23 , 26C View FIGURE26 ) 2.2 times wider than long, with original segmentation indicated by transverse, serrated surface ridge dorsally, and completely fused ventrally. Copulatory pore located medially, and with obscure shape.

Anal somite ( Figs. 23A View FIGURE 23 , 26A View FIGURE26 ) twice wider than long, with well-developed anal operculum presenting dense carpet of setules along posterior margin, and pair of dorsal sensilla.

Caudal rami ( Figs. 26A–C View FIGURE26 , 27A, B View FIGURE 27 ) trapezoidal or square shaped (ventral view), 1.2 to 1.3 times as long as width, with 1 medial spinular row at midway of outer margin laterally and ventrally, and distal spinular row dorsally and ventrally. Caudal ramus bearing 7 setae: seta I naked, shorter than ramus width, and located anterolaterally; seta II naked, almost as long as ramus width, and located dorsolaterally at midway along outer margin; seta III bipinnate, almost as long as ramus length, and located posterolaterally; seta IV bipinnate, stout, 0.2 times as long as seta V, and located at outer posterior margin; seta V strongest, bipinnate, with anterior part rather wide and smooth, located at inner posterior margin, and spine-shaped; seta VI bipinnate and almost as long as seta I; seta VII biarticulate, pinnate, and located at midway along dorsal side.

Antennule ( Figs. 25A View FIGURE 25 ) almost as in N. minutus except for segments 2 and 4 presenting cluster of tiny setules. Segment 2 with 5 pinnate setae (2 setae proximally bulbiform, arrowed in Fig. 25A View FIGURE 25 ). Armature formula: 1-[1], 2-[4 + 5 pinnate], 3-[6+ (1 + ae)], 4-[1], 5-[8 + acrothek].

Antenna ( Fig. 25B View FIGURE 25 ) almost as in N. minutus except for abexopodal setae ornamentation (1 pinnate and 1 naked).

Mandible ( Fig. 25C View FIGURE 25 ) almost as in N. minutus except for mandibular palp size (relatively broad), with 5 setae [1 basal (pinnate), 3 exopodal (2 pinnate and 1 naked), and 1 endopodal (naked)].

Maxillule ( Fig. 25D View FIGURE 25 ) almost as in N. minutus except for total number of elements along distal margin of praecoxal arthrite (8 stout naked spines/setae and 1 bipinnate seta). Ornamentation of 5 basal setae naked.

Maxilla ( Fig. 25E View FIGURE 25 ) almost as in N. minutus except for elements of syncoxal endites without spinular ornamentation at distal margin.

Maxilliped ( Fig. 25F View FIGURE 25 ) almost as in N. minutus except for length of 1 accessory seta (reaching to distal margin of claw) at proximal region of distal endopod segment.

P1–P4 (Fig. 28A–D) with smooth and short concave intercoxal sclerite (not illustrated). Praecoxa somewhat triangular, shorter than coxa, and without spinules except for P1. Coxa with 1 spinular row (P2, P3 and P4) on anterior surface, and row of strong outer spinules (P1, P2, P3 and P4). Basis with row of strong outer spinules near insertion of exopod, and row of very small (P1) and long distal spinules (P1, P2, P3 and P4) near insertion of endopod. Additional ornamentations including row of inner spinules (P1) or setules (P2 and P3). Outer seta naked (P1 and P2) or bipinnate (P3 and P4), and inner spine present on P1. Exopod 3-segmented, all segments subequal, and exp-1 to -3 (P1, P2, P3 and P4) with robust outer spinules. Exp-1 to -3 (P1 and P3), and exp-1 to -2 (P4) with row of inner setules. Exp-1 to -3 (P1, P2 and P3) and exp-2 to -3 (P4) with pinnate outer spines. Exp-2 (P2, P3 and P4), and exp-3 (P1, P2, P3 and P4) with pinnate inner subdistal, distal and outer terminal setae. P4 exp-3 with short inner subdistal pectinate spine. Endopod 2-segmented in P1–P3 or 1-segmented in P4. Enp-1 to -2 (P1, P2 and P3) with robust outer distal spinules. Enp-1 to -2 (P1), and enp-2 (P3) with row of inner setules. All setae on P1, P2, P3 and P4 endopods pinnate including inner apical short seta on P4 endopod (Fig. 28D). Armature formula as follows: P5 ( Fig. 26D View FIGURE26 ) fused with somite, exopod and baseoendopod fused, both baseoendopod confluent, and baseoendopod with inner spinules posteriorly. Endopodal lobe with 2 pectinate (1 short and 1 extremely long), and 2 small sub-equal naked setae. Exopodal lobe with 4 pinnate setae.

P6 ( Fig. 26C, E View FIGURE26 ) with small triangular flap, and each flap bearing 1 small distal naked seta. Description of male (based on allotype and paratypes). Body ( Fig. 29A View FIGURE 29 ) as in female except for total body length ranged from 426 to 313 µm (mean = 369 µm, n = 2; allotype: 313 µm, measured from tip of rostrum to posterior margin of caudal rami). Maximum width ranged from 132 to 156 µm (mean 144 µm, n = 2; allotype: 132 µm, measured at posterior margin of cephalothorax). Urosome/prosome length ratio 0.6 and body length/width ratio about 3.1. Cephalothorax ( Fig. 29A View FIGURE 29 ) almost as in female, as long as width, and comprising 31.2% of total body length. Body ornamentation ( Fig. 29A View FIGURE 29 ), anal somite ( Fig. 29A View FIGURE 29 ), rostrum (not illustrated), antenna (not illustrated), mouth parts (not illustrated), P1–P2, and P4 (not illustrated) as in female.

Prosome 4-segmented ( Fig. 29A View FIGURE 29 ), comprising cephalothorax (bearing first pedigerous somite), and 3 free somites. Posterior margin of prosomites serrated, and with sensilla as in female.

Urosome 6-segmented ( Fig. 29A, B View FIGURE 29 ) comprising of P5-bearing somite, genital somite, 3 free abdominal somites, and anal somite. Posterior margin of urosomites serrated except for anal somite, and with sensilla as in female. Urosomite 3 to 5 with longitudinal row of spinules along ventral posterior margin.

FIGURE 28. Nannopus parvus sp. nov., line drawings, A–B & D, paratype ♀ 1; C, paratype ♀ 2: A, P1; B, P2; C, P3; D, P4.

Genital somite ( Fig. 29B View FIGURE 29 ) homologous to anterior part of genital double-somite in female, second and third urosomite well segmented in ventral view.

Caudal rami ( Fig. 29B, C, D View FIGURE 29 ) presenting seta IV sparsely pinnate and slender, seta V shorter than in female, and seta VI and VII naked.

Antennule ( Figs. 30C View FIGURE 30 , 31A, B View FIGURE 31 ) chirocer, 7-segmented with strong geniculation between segments 5 and 6. Segment 4 representing by small incomplete segment with only 1 naked seta. Armature formula as follows: 1-[1], 2-[4 + 5 pinnate], 3-[3], 4-[1], 5-[6], 6-[9 + (1+ae)], 7-[7 + acrothek]. Apical acrothek consisting of minute aesthetasc and 2 naked setae.

P3 ( Figs. 30D View FIGURE 30 , 31C, D, E View FIGURE 31 ) exopod 3-segmented, and exp-1 to -2 with row of inner setules. Endopod 2- segmented, enp-2 outer spine fused to segment forming short apophysis with sharp and curved tip, and inner 2 setae pinnate as in female.

P5 ( Fig. 31F View FIGURE 31 ) fused with somite, exopod and baseoendopod fused, and both baseoendopods confluent. Baseoendopod with inner spinules, and row of setules posteriorly. Endopodal lobe with 2 sub-equal pectinate setae (outer pectinate seta 0.3 times as long as one in female, arrowed in fig. 31F) and 2 sub-equal naked setae. Exopodal lobe with 4 unequal elements [outermost and innermost setae naked (arrowed in Fig. 31F View FIGURE 31 ) and medial 2 setae bipinnate].

P6 ( Figs. 29B View FIGURE 29 , 31G View FIGURE 31 ) asymmetrical with small functional flap on left side, with 3 elements (2 bipinnate and 1 naked), and median element longer than remaining 2 elements.