Xystodesmus bifurcus sp. nov.

urn:lsid:zoobank.org:act: 1B1E13DC-453C-4A7E-B483-EA490FC4C1C3

Figs 5, 10C, 11A, 12E–F, 15–16

Diagnosis

A medium-sized Xystodesmus with typical colour pattern, i.e., bright orange spots on all paranota. Differs from all other congeners by having a strongly bifurcated acropodite, and by the 2 nd legpair of females simple, without coxal projections.

Etymology

Refers to the two-forked acropodite of the male gonopod (bi + furca, furcus = two + fork, forked, in Latin). Adjective, masculine.

Type material

Holotype SOUTH KOREA • ♂; Gangwon Prov., Pyeongchang District, Yongpyeong Town, Nodong-ri, Mt. Gyebang-san; 37°41′43.1″ N, 128°28′42.7″ E; 850 m a.s.l.; 9 Jun. 2023; G. Kim leg.; GenBank nos: PV446393 (COI), PV544258 (EF1-α); LEGOA030038 PC10.

Paratypes SOUTH KOREA • 1 ♂; same collection data as for holotype; GenBank nos: PV446394 (COI), PV544259 (EF1-α); HNIBRIV8508 PC11 • 1 ♀; same collection data as for holotype; GenBank nos: PV446392 (COI), PV544257 (EF1-α); LEGOA030039 PC09 • 1 ♂; Gangwon Prov., Pyeongchang Town, Jinbumyeon, Odaesan-ro, Mt. Odae-san; 37°44′23.3″ N, 128°35′8.9″ E; 14 Apr. 2023; G. Kim leg.; GenBank nos: PV446397 (COI), PV544262 (EF1-α); HNHM diplo-04558 PC14 • 1 ♀; Gangwon Prov., Inje Town, Gwidun-ri, Mt. Jeombong-san; 38°1′23.0″ N, 128°25′53.8″ E; 940 m a.s.l.; 8 Aug. 2024; H. Yu and D. Kim leg.; HNHM diplo-04559 IJ04 • 1 ♂; same data as for preceding; GenBank nos: PV446395 (COI), PV544260 (EF1-α); LEGOA030041 IJ02 24 • 1 ♀; same data as for preceding; GenBank nos: PV446396 (COI), PV544261 (EF1-α); LEGOA030042 IJ03 24 • 1 ♀; same data as for preceding; LEGOA030043 IJ05 24 • 1 ♀; Gangwon Prov., Inje Town, Buk-myeon, Yongdae-ri, Yongdae recreational forest; 38°14′3.0″ N, 128°20′49.2″ E; 480 m a.s.l.; 7 Aug. 2024; H. Yu and D. Kim leg.; LEGOA030044 IJ01 24 • 1 ♀; Gangwon Prov., Inje Town, Girin-myeon, Jindong-ri, Gachilbong Peak; 37°59′17.5″ N, 128°24′27.7″ E; 620 m a.s.l.; 14 Aug. 2023; D. Kim leg.; LEGOA030045 IJ03 23 • 1 ♀; Gangwon Prov., Inje Town, Girin-myeon, Jindong-ri, Gachilbong Peak; 37°59′17.5″ N, 128°24′27.7″ E; 620 m a.s.l.; 9 Aug. 2024; H. Yu and D. Kim leg.; LEGOA030046 IJ06 24 • 1 ♀; same data as for preceding; LEGOA030047 IJ07 24 • 1 ♀; Jellanam Prov., Gurye-gun, Ganjeon-myeon, Jungdae-ri, Mt. Baekunsan; 35°07′55.8″ N, 127°36′12.6″ E; 580 m a.s.l.; 2 Sep. 2023; D. Kim leg.; LEGOA030048 WJ03 • 1 ♀; Gyeonggi Prov., Gapyeong-gun, Dumil-ri, Mt. Daegeumsan; 37°48′31.0″ N, 127°25′45.2″ E; 270 m a.s.l.; 12 Aug. 2023; D. Kim leg.; LEGOA030049 GP05 • 1 ♀; Gyeongsangnam Prov., Geoje District, Mundong Town, Mundong Recreational forest; 34°51′42.9″ N, 128°40′6.4″ E; 19 May 2024; G. Kim and D. Kim leg.; LEGOA030050 GJ07.

Description

HEAD. Smooth, with 1+1 large frontal setae and several smaller ones on clypeus and around antennal sockets; epicranial suture distinct. Antennae slightly bent; article 1 globose; article 2 longer; articles 3–5 subequal in length; article 6 longer, hairy; article 7 small, its length equal to width, with 4 apical sensory cones.

COLLUM. Subtrapezoidal, convex, its length 2.5 times as long as that of metatergite 2, lateral edges directed ventrad, anterior margin with weak ridge.

BODY. Collum and first four rings narrower, body sides between rings 5–14 parallel, then gradually tapering towards telson. Proterga and metaterga completely smooth, metaterga with transverse depression in middle. No trace of tubercles or punctation on metaterga. Posteriolateral edge of paranota 2–4 rounded, of 5–6 slightly pointed, from 7 onwards triangular in shape, with weak excavation on the posterior edge of each of the metaterga. Pore formula mostly typical for Polydesmida, pores on rings 5, 7, 9–10, 12–13, and 15–19, in lateral position on slightly swollen paranota. Rings 15–19 gradually tapering, posterolateral projections becoming more pointed.

TELSON. Epiproct protruding, in dorsal view triangular, in lateral view distinctly curved, with 3+3 setae on sides, and with 1+1 setae apically; paraprocts (anal valves) smooth, with 2+2 setae on median ridges; hypoproct semicircular, with 1+1 setae on small tubercles.

LEGS. Bases of midbody legpairs well separated in males by 1.1–1.7 mm, in females by 1.6–2.0 mm, sterna smooth and wide, pro- and metasterna well separated. Prefemur of legs from ring 7 with well-developed ventral spine, increasingly larger from midbody legs onwards; femur about as long as prefemur, slightly clavate; postfemur short, half as long as femur; tibia slender, setose, as long as postfemur and tarsus; tarsus densely setose; all legs with claws.

MEASUREMENTS. Males (based on 4 specimens): total body length 27–30 mm, midbody width (including paranota) 4.9–5.1 mm, metatergal length 1.2–1.4 mm, midbody prozonite width 3.5–3.7 mm, collum width 4.0– 4.4 mm, median collum length 1.9–2.4 mm. Females (based on 11 specimens): total body length 28–33 mm, midbody width (including paranota) 5.3–6.4 mm, metatergal length 1.2–1.6 mm, midbody prozonite width 3.9–4.9 mm, collum width 3.9–5.4 mm, median collum length 1.7–2.2 mm.

COLOURATION (Fig. 12E–F). Specimens preserved in ethanol: dorsum pale brownish, prozonite lighter, metazonite, including epiproct, darker; paranota bright orange on all rings, including collum, except ring 19. Head, antennae, legs, and whole ventral side white.

MALE CHARACTERS. Collum relatively thin and long (see Measurements). Coxae of legpair 2 with pair of small protruding processes, of legpair 3 with small triangular, of legpairs 4 and 5 with long and pointed processes. Other legs and sterna without modifications. Gonopods (Fig. 5A–D): composed of three conspicuous processes, one considered as prefemoral process (pfp), and the other one, the acropodite (a), strongly bifurcated into two processes subequal in length. Coxa stout, 1.5 longer than wide, without coxal apophysis, but with single apophyseal macroseta (ms) on dorsal side. Cannula on mesal side, starting near macroseta, then connected to prefemur and continuing in prostatic groove (pg). Prefemur short, stout, bent dorsad, densely setose; prefemoral process (pfp) long, broad at base, thin and transparent (often broken), gradually and straight tapering toward pointed tip. Acropodite (a) densely setose, distally bifurcate in two parts: solenomere (sl), bent ventrad, gradually tapering towards tip and carrying prostatic groove (pg), and shorter pointed process (p), slightly bent toward solenomere.

FEMALE CHARACTERS. Body of females relatively larger (longer and wider) than that of males; collum, nevertheless, wider and shorter than males (see Measurements); other somatic characters, including colouration and strong prefemoral ventral spines (Fig. 11A: ps), similar. All coxae, including those of legpair 2, and sterna without modification (Fig. 10C). Cyphopods in situ held closely behind legpair 2; opening oval; valves (v) of subequal size, pentagon-shaped, ventral edges each with small peak (Fig. 10C), operculum (op) laterally closely overlaying, receptacles (r) deeply embedded under valves.