Xystodesmus shirozui

Xystodesmus shirozui (Takakuwa, 1942) Figs 4, 10B, 12C–D, 15–16 Rhysodesmus shirozui Takakuwa, 1942b: 239, fig. 5. Rhysolus shirozui – Miyosi 1959: 80, fig. 55. Riukiaria shirozui – Shinohara 1977: 119. Xystodesmus shirozui – Tanabe & Shinohara 1996: 1485–1486, figs 3–7, 11m –n, 13c–d, 16c–d, 17o-p. Diagnosis A medium-sized Xystodesmus with a strong colour pattern typical for the genus. Differs from congeners by male gonopod conformation having three subequal processes: a prefemoral process (pfp, with a small accessory spine, s), a femoral process (fp), and an acropodite with solenomere (sl) (Fig. 4A–F). Type material (not examined) JAPAN • 1 ♂; “Tusima, ” (= Japan, Nagasaki Pref., Tsushima Island, Kamiagata Distr., Kamitsushima Town, Hitakatsu, Mt. Gongen-san, see Tanabe & Shinohara 1996); Takasi Shirozu leg.; Takakuwa’s private collection, including type material of many species, considered lost (Tanabe & Shinohara 1996). Other material examined SOUTH KOREA • 1 ♂; Gyeongsangnam Prov., Geoje District, Mundong Town, Mundong Recreational forest; 34°51′38.7″ N, 128°40′20.0″ E; 14 May 2023; D. Kim leg.; GenBank nos: PV446387 (COI), PV544252 (EF1-α); HNIBRIV12832 GJ03 23 • 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.; GenBank nos: PV446386 (COI), PV544251 (EF1-α); LEGOA030023 GJ02 23 • 1 ♂; Jellanam Prov., Hwasun Town, Baega-myeon, Songdan-gil 479-55, Mt. Bakeasan; 35°10′4.8″ N, 127°11′10.3″ E; elev. 480 m; 25 Sep. 2023; G. Kim leg.; HNHM diplo-04556 HS13 23 • 1 ♂; same data as for preceding; GenBank nos: PV446398 (COI), PV544263 (EF1-α); LEGOA030025 HS11 23 • 1 ♂; same data as for preceding; GenBank nos: PV446399 (COI), PV544264 (EF1-α); LEGOA030026 HS12 23 • 1 ♂; Jellanam Prov., Damyang Town, Wolsan-myeon, Yongheung-ri, San 86-26; 35°20′22.9″ N, 126°53′25.8″ E; 6 Jul. 2024; G. Kim leg.; GenBank nos: PV446403 (COI), PV544268 (EF1-α); LEGOA030027 DY05 • 1 ♂; same data as for preceding; GenBank nos: PV446407 (COI), PV544272 (EF1-α); LEGOA030028 DY10 • 1 ♀; same data as for preceding; GenBank nos: PV446400 (COI), PV544265 (EF1-α); LEGOA030029 DY01 • 1 ♀; same data as for preceding; GenBank nos: PV446401 (COI), PV544266 (EF1-α); LEGOA030030 DY02 • 1 ♀; same data as for preceding; GenBank nos: PV446402 (COI), PV544267 (EF1-α); LEGOA030031 DY03 • 1 ♀; same data as for preceding; GenBank nos: PV446404 (COI), PV544269 (EF1-α); LEGOA030033 DY06 • 1 ♀; Jellanam Prov., Hwasun Town, Baega-myeon, Songdan-gil 479-55; 35°10′22.1″ N, 127°11′0.6″ E; 6 Jul. 2024; G. Kim leg.; HNHM diplo-04557 HS04 24 • 1 ♂; same data as for preceding; LEGOA030034 HS05 24 • 1 ♀; same data as for preceding; LEGOA030035 HS02 24 • 1 ♀; same data as for preceding; LEGOA030036 HS03 24 • 1 ♀; Jellanam Prov., Gurye District, 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.; LEGOA030037 GR02. Description HEAD. Smooth, no frontal setae, only small ones on edge of clypeus, and none around antennal sockets; epicranial suture distinct. Antennae bent; article 1 globose; articles 2–6 long, straight, and subequal in length, about 2.5 times as long as article 1, all moderately setose; article 7 small, densely setose, length subequal to width, with 4 apical sensory cones. COLLUM. Convex, subtrapeziform, length 1.5 times as large as that of metatergite 2, lateral edges pointed, anterior margin semicircular, with a visible ridge, posterior margin straight with lateral parts directed forward. BODY. Collum and first four rings narrower, gradually widening to ring 5, body sides between rings 5–15 parallel, then gradually tapering towards telson. Proterga and metaterga completely smooth, shiny, metaterga with strong transverse medial depression, without any tubercles or punctation. Posteriolateral edge of paranota 2–4 rounded, of 5 slightly pointed, from 6 onwards triangular in shape, with weak excavation on posterior edge of each of the metaterga, all with strong lateral ridge. 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 16–19 gradually tapering, posterolateral projections becoming more pointed, on 17 triangular, on 18–19 long, almost as long as length of metaterga. TELSON. Epiproct protruding, in dorsal view triangular, in lateral view only slightly curved downwards, with 4+4 setae sitting on tubercles of sides, and with 2+2 stronger setae apically; paraprocts (anal valves) smooth, with 2+2 setae on median ridges; hypoproct semitriangular, with 1+1 setae on small tubercles. LEGS. Bases of midbody legpairs well separated in males by 1.2–1.5 mm, in females by 1.3–1.6 mm, sterna smooth and wide, pro- and metasterna well separated. Coxa of legs from ring 7 short, shorter than prefemur, which has well-developed ventral spine, increasing in size from legs 9 onwards; femur 1.2 times as long as prefemur, clavate; postfemur short, stout; tibia and tarsus of about same length; podomeres distally increasingly setose; curved claws on all legs. MEASUREMENTS. Males (based on 7 specimens): total body length 24–28 mm, midbody width (including paranota) 4.4–5.4 mm, metatergal length 0.9–1.4 mm, midbody prozonite width 3.0– 3.6 mm, collum width 3.3–3.9 mm, median collum length 1.4–1.9. Females (based on 9 specimens): total body length 21–30 mm, midbody width (including paranota) 4.3–5.7 mm, metatergal length 0.9–1.3 mm, midbody prozonite width 3.2–4.3 mm, collum width 3.5–4.2 mm, median collum length 1.4–1.9 mm. COLOURATION (Fig. 12C–D). Preserved specimens in ethanol. Dorsum of collum, prozonite, metazonite, and proximal part of epiproct equally dark brown, nearly black, tip of epiproct lighter; all metaterga paramedially with large, marbled patches, adjacent paranota with wide bright red or orange spots, collum included, but last ring excluded. Head brown, antennae, legs, and venter white. MALE CHARACTERS. Coxae of legpair 2 with protruding, pointed processes, of legpair 3 with very small, of legpairs 4–5 with longer and pointed, and of legpair 6 again with small processes. Other legs and sterna without modifications. Gonopods (Fig. 4A–F): coxa stout, about as long as wide, without coxal apophysis, but with small hump next to single apophyseal macroseta (ms) on dorsum. Cannula on mesal side, starting near macroseta, then connected to prefemur and continuing in prostatic groove. Prefemur short and wide, densely setose; prefemoral process (pfp) long and flat, parallel and nearly as long as acropodite, with small spine on dorsal side halfway (s), last ⅓ flattening, slightly twisted, turning ventrad, apical part pointed. Acropodite with two processes, solenomere (sl) straight and long, distally slightly tapering, tip abruptly narrow and pointed, sometimes subapically with a small, pointed extra process (sp) (Fig. 4E–F); and another process, called femoral (fp) after Hoffman (1956: 98, fig. 1), which starts at base of acropodite close to prefemoral process, its shape and length also similar to it, flat and parallel-sided, sometimes gradually tapering, until last ⅓, then ends in pointed tip. Prostatic groove runs dorsally on mesal side of solenomere. FEMALE CHARACTERS. Total body length generally shorter than males, other measurements and somatic characters similar, including colouration, shape of collum, tergites and epiproct, as well as strong prefemoral ventral spines, starting on legpair 5: coxae of legpair 2 with small triangular projection (Fig. 10B), remaining legs without any sternal or coxal modifications. Cyphopods in situ held closely behind legpair 2, in joint transversal, semicircular opening; valves (v) of subequal size, ventral edges jagged, medially with weak depression for genital opening, operculum (op) laterally closely overlaying, receptacles (r) deeply embedded under valves. Distribution Xystodesmus shirozui in South Korea occurs in the southernmost parts, Gyeongsangnam and Jellanam provinces (Fig. 15). Remarks First, we have to emphasize that our identification is largely based on the high variability of the species outlined by Tanabe & Shinohara (1996). Some characters, including those mentioned in our diagnosis, slightly differ from those given by them who considered, for instance, all three gonopodal processes “prefemoral”. Considering the geographical distribution of our samples, especially that of Geoje Island (Fig. 15), we feel confident that the South Korean populations are within the individual variation of the Japanese X. shirozui, the type locality of which, Tsushima Island, is just 80 km away from Geoje Island in the East Sea. Xystodesmus shirozui is new to the fauna of Korea.