Nannopus cylindricus, Vakati & Lee, 2021

Vakati, Vinod & Lee, Wonchoel, 2021, - On- two- new- species- of- Nannopus- Brady, - 1880 - (Copepoda: - Harpacticoida Nannopodidae) - from-intertidal-mudflats-of-the-Korean-west-coast- (Yellow-Sea), Zootaxa 5051 (1), pp. 529-549 : 531

Nannopus cylindricus ­sp.­nov.­

( Figs. 2–3 )

Type­ locality. Intertidal mudflat, St-6a— Gilsang-myeon , Ganghwa Island, Korea, Yellow Sea, 37°35’55.9”N 126°30’49.2”E ( Fig. 1 ) .

Type­material. Holotype: 1 female adult in 70% ethanol (NIBRIV0000860820). Samples were collected by Vinod Vakati, 06 March 2015.

Etymology. The species epithet is derived from the Latin “cylindricus”, cylindrical, and alludes to the shape of the proximal region of caudal seta V.

Description­of­female­(based­on­holotype). Body ( Fig. 2A–B ) fusiform narrow, total body length 719 μm, measured from tip of rostrum to posterior margin of caudal rami. Maximum width 218 μm, measured at posterior margin of cephalothorax. Boundary between prosome and urosome clearly visible, urosome/prosome length ratio 0.73, and body length/width ratio about 3.2. Body ornamentation consisting of dorsal denticles, and horizontal row of setules as in N. ganghwaensis (see Vakati et al. 2016: 217, Fig. 3A–D ). Cephalothorax ( Fig. 2A ) anteriorly attenuated in dorsal view, comprising 28% of total body length, posterior margin serrated, with several paired sensilla and one row of sensilla ( Fig. 2A ).

Rostrum as in N. ganghwaensis and with pair of sensilla as in N. didelphis (see Fiers & Kotwicki 2013: 41, Fig. 4G ; Vakati et al. 2016: 216, Fig. 2C ).

Prosome ( Fig. 2A ) 4-segmented, comprising cephalothorax and three subequal pedigerous somites. P1-bearing somite fused to cephalothorax, posterior margin of free pedigerous somites serrated, and with row of sensilla posteriorly.

Urosome ( Fig. 2A–B ) tapering posteriorly, comprising P5-bearing somite, genital double-somite, two free abdominal somites, and anal somite. Posterior margin of P5-bearing somite and first half of genital double-somite serrated dorsally; second half of genital double-somite, fourth and fifth urosomites with posterior margin serrated dorsally and ventrally; each somite with sensilla dorsally except for penultimate somite and one row of spinules ventrally. Genital double-somite as in N. ganghwaensis (see Vakati et al. 2016: 221, Fig. 7A), completely fused ventrally, distinct dorsally and laterally ( Fig. 2A–B ), with serrated posterior margin dorsally, and smooth ventrally except for spinular row along posterior margin; copulatory pore not visible (completely translucent).

Anal somite ( Figs. 2A , 3A–B ) with well-developed operculum, covered with setules posteriorly; almost as long as wide, with pair of dorsal sensilla and with one row of spinules on either side of somite ventrally.

Caudal rami ( Fig. 3A–C ) cylindrical, clearly separated from anal somite, 1.7 (in dorsal view) and 2 (in ventral view) times as long as wide. Ornamentation consisting of setules as in N. ganghwaensis (see Vakati et al. 2016: 222, Fig. 8A–B), and row of spinules along posterior margin ventrally ( Fig. 3B ). Caudal ramus bearing seven setae: seta I naked, shorter than ramus width, located anterodorsally; seta II naked, shorter than ramus width, inserted anterodorsally midway and close to outer margin; seta III naked, almost as long as ramus length, and inserted anterolaterally midway along outer margin; seta IV bipinnate, located distally, and 0.5 times as long as seta V; seta V longest, bipinnate, located distally, anterior part inflated and heavily cylindrical (arrowed in Fig. 3A–C ); seta VI small, and naked; seta VII triarticulate, naked, and located midway along inner margin.

Antennule, antenna, mouth parts, P1– P6 as in N. ganghwaensis (see Vakati et al. 2016: 218–221, Figs. 4A–F , 5A–B, 6A–B, 7A–D, E).

Male. Unknown.

Figures

FIGURE­2.­Nannopus cylindricus sp.­nov. (holotype ♀). A, habitus, dorsal; B, habitus, lateral.

FIGURE­3.­Nannopus cylindricus sp.­nov. (holotype ♀). A, anal somite and caudal rami, dorsal (cylindrical shape arrowed); B, anal somite and caudal rami, ventral (cylindrical shape arrowed); C, anal somite and caudal ramus, lateral (cylindrical shape arrowed).

FIGURE­1. Map showing the sampling localities and distribution of all valid Korean species identified and described so far. The black line between Stations 6a and 6b represents a man-made road with no gap for water entry from either side. Stations 1 to 15 refer to the study sites in Vakati et al. (2019), station 16 refers to the study site in Kim et al. (2017).

FIGURE­4.­Nannopus robustus sp.­nov. (holotype ♂). A, habitus, dorsal; B, habitus, lateral.