Diosaccus koreanus, Lim & Bang & Moon & Back, 2020

Lim, Byung-Jin, Bang, Hyun Woo, Moon, Heejin & Back, Jinwook, 2020, Integrative description of Diosaccus koreanus sp. nov. (Hexanauplia, Harpacticoida, Miraciidae) and integrative information on further Korean species, ZooKeys 927, pp. 1-35 : 1

publication ID	https://dx.doi.org/10.3897/zookeys.927.49042
publication LSID	lsid:zoobank.org:pub:24272A94-472E-4F9C-836F-41D11E62C353
persistent identifier	https://treatment.plazi.org/id/64547C65-0584-47D1-BEDF-AC6DDD748CB6
taxon LSID	lsid:zoobank.org:act:64547C65-0584-47D1-BEDF-AC6DDD748CB6
treatment provided by	ZooKeys by Pensoft
scientific name	Diosaccus koreanus
status	sp. nov.

Treatment

Diosaccus koreanus sp. nov. Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5 , 6 View Figure 6 , 7 View Figure 7 , 8 View Figure 8

Material examined.

Holotype. Republic Of Korea ∙ Ulleungdo Island; 37°31'36.56"N, 130°49'41.77"E; 25 July 2017; B. Jinwook leg.; hand net, 0.5 m ∙ 1 ♀ (MABIK CR00247255) was dissected on 14 slides (Table 1 View Table 1 ) ∙ GenBank accession number for COI sequence: MN996281. Paratypes. Republic Of Korea (Table 1 View Table 1 ) ∙ 1 ♂ (MABIK CR00247257) was dissected on 8 slides and observed ∙ 4 ♀♀ (MABIK CR00247256, CR00247258 - CR00247260) were preserved in 99% alcohol ∙ GenBank accession numbers: MN996277 to MN996280 (COI) and MT002900 to MT002902 (18SrRNA).

Description.

Female. Body (Figs 1 View Figure 1 , 2 View Figure 2 ): Total length, from anterior margin of rostrum to posterior margin of caudal rami, 1135 μm (N = 5, mean = 1133 μm; Fig. 1 View Figure 1 ); maximum width 340 μm, measured at distal cephalothorax; body cylindrical, not dorsoventrally depressed, and with minute dorsal sensilla; rostrum well developed, defined at base, trapezoid in shape, with round apex and 2 sensilla (Figs 1A View Figure 1 , 2A View Figure 2 ); cephalothorax sub-triangle with sensilla and smooth margin; second and third urosomites fully fused ventrally, but with transverse ridge on dorsal and lateral surfaces indicating original segmentation (Figs 1A, B View Figure 1 , 6B View Figure 6 ); anal operculum not well developed, with spinular tuft (Fig. 2D View Figure 2 ).

Caudal rami (Fig. 2D, E View Figure 2 ): Parallel, ca 1.5 times longer than maximum width, dorsal surface with small bumps; each ramus with 7 setae: seta I strong, pinnate; setae II bare on distal corner; seta III blunt spine; setae IV and V strong; seta VI pinnate; seta VII bare, triarticulate at base.

A1 (Fig. 2A View Figure 2 ): Slender, 8-segmented; seg-2 longest, ca 1.2 times as long as seg-3; seg-4 with sub-cylindrical pedestal armed with aesthetasc fused at base to 1 long bare seta; armature formula: 1-[1], 2-[11], 3-[9], 4-[3 + (1+ae)], 5-[2], 6-[4], 7-[4], 8-[3+acrothek]; apical acrothek of short aesthetasc fused basally to 2 bare setae.

A2 (Fig. 2B, C View Figure 2 ): 3-segmented, with coxa, allobasis, and free 1-segmented enp; coxa small and bare; allobasis without abexopodal seta; exp 1-segmented, with 2 lateral and 2 apical pinnate setae; free enp with 2 pinnate setae and 2 long spines laterally and with 1 bare seta, 2 spines, and 3 geniculate setae along distal margin.

Mandible (Fig. 3A View Figure 3 ): Gnathobase with several blunt teeth; palp basis with 2 inner pinnate setae; exp 1-segmented with 2 pinnate distal setae; enp with 2 lateral and 6 distal setae.

Maxillule (Fig. 3B, C View Figure 3 ): Praecoxa trapezoidal in shape, without ornamentation; arthrite well developed, with 2 juxtaposed setae near midpoint of anterior surface, 4 strong teeth-like spines and 3 tuft spines along distal margin; coxa fused with cylindrical endite, with 1 pinnate seta; basis fused with endite, with 1 bare and 5 pinnate setae; exp 1-segmented, with 2 pinnate setae distally; enp 1-segmented, with 4 pinnate setae along distal margin.

Maxilla (Fig. 3D View Figure 3 ): Syncoxa with 2 endites; proximal endite with 2 strong spines and 1 bare seta among distal margin; second endite with 1 strong spine, 1 bare seta, and 1 tuft-like seta; allobasis developed into cylindrical process, with 2 strong spines and 2 bare setae; enp 1-segmented, with 2 bare and 3 pinnate setae.

Mxp (Fig. 3E View Figure 3 ): 4-segmented, with syncoxa, basis, and 2-segmented enp; syncoxa with 2 pinnate setae distally; basis elongate and robust, with 2 small bare setae (Fig. 3E View Figure 3 , arrow) and roughly ornamented with rows of spinules along inner margin; enp-1 with 1 bare and 1 pinnate setae; enp-2 forming strong claw ornamented with row of spinules among inner proximal half.

Swimming legs (Figs 4 View Figure 4 , 5 View Figure 5 ): Biramous; P1-P4 with coxa, basis, and 3-segmented exp and enp; each ramus ornamented with setules or spinules along outer margins as figured.3

P1 (Fig. 4A, B View Figure 4 ): Coxa ornamented with inner spinules; basis with 1 outer and 1 inner pinnate setae; exp-1 with 1 outer spine; exp-2 with 1 outer spine and 1 inner pinnate seta; exp-3 with 3 spines and 1 bare seta; enp-1 ornamented with row of spinules on inner proximal half, ca 2 times longer than exp, with 1 pinnate seta; enp-2 with 1 small bare seta on inner distal corner, enp-3 with 2 strong spines distally and 1 bare seta near inner distal corner.

P2 (Fig. 4C View Figure 4 ): Coxa ornamented with row of spinules on outer margin; basis with 1 outer bare seta near distal corner; exp-1 with 1 outer spine, ornamented with a row of long setules along inner margin; exp-2 with 1 outer spine and 1 inner pinnate seta, ornamented with row of setules along outer margin; exp-3 with 2 outer spines and 2 apical and 2 inner pinnate setae; enp-1 with 1 inner pinnate seta, ornamented with long setules along outer margin; enp-2 with 2 pinnate inner setae; enp-3 with 1 outer, 2 distal, and 1 inner pinnate setae.

P3-P4 (Fig. 5A, B View Figure 5 ): Coxa ornamented with rows of spinules on outer margin; basis with 1 outer bare seta near distal corner; exp-1 with 1 outer spine, ornamented with row of long setules along inner margin; exp-2 with 1 outer spine and 1 inner pinnate seta, ornamented with row of spinules along outer margin; exp-3 with 3 outer spines, 2 apical and 3 inner pinnate setae; enp-1 with 1 inner seta, ornamented with long setules among outer margin; enp-2 with 2 inner pinnate setae [P3] or 1 inner pinnate seta [P4]; enp-3 with 1 outer spine, 2 apical pinnate and 2 inner pinnate setae.

Armature formulae as follows:

P5 (Fig. 6C View Figure 6 ): Defined at supporting somite; each side of endopodal lobe separated, with 6 spine-like setae; exp with 6 setae, second inner element longest.

P6 (Fig. 6A, B View Figure 6 ): Fused with supporting somite, with 3 bare setae, innermost seta longest.

Male. Body (Fig. 7A View Figure 7 ): Total length, from anterior margin of rostrum to posterior margin of caudal rami, 880 μm; maximum width 262 μm, measured at distal cephalothorax; general body shape, ornamentation, and sensilla pattern almost identical to those of female, but with sexual dimorphisms observed in A1, P1, P2, P5, P6, and genital somites.

A1 (Fig. 8C, D View Figure 8 ): Subchirocer 10-segmented, robust; seg-3 with aesthetasc fused at base to 1 bare seta; seg-5 swollen, with aesthetasc fused at base to 1 bare seta; armature formula: 1-[1], 2-[10], 3- [4+(1+ae)], 4-[2], 5-[4+(1+ae)], 6-[2 bare], 7-[1], 8-[1], 9-[4], 10-[5+(1+ae)].

P1 (Fig. 8A View Figure 8 ): General shape of P1 similar to that of female, except basis; basis with 1 outer pinnate seta and 1 wrinkled process near base of outer seta.

P2 (Fig. 8B View Figure 8 ): Enp 2-segmented; enp-1 with 1 inner bare seta and ornamented with row of long setules along outer margin; enp-2 with 1 inner bare seta on small disk (Fig. 8B View Figure 8 , arrow) of which middle inner edge and 1 longest bare seta, 3 pinnate inner setae, and 1 strong spinulose seta apically.

P5 (Fig. 7D View Figure 7 ): Fused medially; plate of benp fused each side; basal part with 1 bare seta; endopodal lobe with 2 spinulose pinnate setae; exp fused at base, with 3 spinulose setae and 1 bare seta.

P6 (Fig. 7E View Figure 7 ): Fused at base, with 2 bare and 1 spinulose setae.

Etymology.

Species name refers to the type locality (i.e., Republic of Korea).

DNA sequences.

In regards to pairwise distances (Tamura-Nei distance) among the 582-bp COI sequences, D. koreanus sp. nov. exhibited intra-specific variation of 0-2.28%, and inter-specific distances of 19.42-22.34% were observed among all three Diosaccus species (Table 3 View Table 3 ). In regards to the 18SrRNA sequences, intra- and inter-specific variations of 0% and 1.46-8.55% were observed (Table 4 View Table 4 ).