Polyconoceras sp. Omine 1962: 1 Omine 1965a: 48 Polyconoceras callosus (Karsch, 1881) Prospirobolus joannise Ikehara and Shimojana 1975: 125 Kikunaga et al. 1993: 91 Yokotsuka 2002: 242 Yokotsuka 2004: 242 Yokotsuka 2011: 242 Acladocricus sp. Omine et al. 1982: 119 Spirobolus sp. Takano 1989: 4 Murakami 1993: 98 Omine 2002: 157 Chigira and Tanaka 2004: 16 Ministry of the Environment 2010: 5 Nakamura and Korsós 2010: 79 Shinohara et al. 2015: 981 Horii 2020: 122 Taxonomic Assessment of a Threatened Large Millipede Endemic to the Southern Ryukyu Islands, Japan: a New Species of Spirobolus (Diplopoda: Spirobolida: Spirobolidae) from the Yaeyama Islands Kato, Taiga Takano, Mitsuo Nakano, Takafumi Shimano, Satoshi Species Diversity 2023 2023-01-12 28 1 23 30 7Q2L8 7559 Brandt, 1833 Brandt 1833 [1039,1284,1369,1394] Diplopoda Spirobolidae Spirobolus Animalia Spirobolida 1 24 Arthropoda genus     Polyconocerassp.:  Omine 1962: 1, 6 (list; as Polyconoxcerus[sic] sp.);  Omine 1965a: 48, fig. 7 (as Polyconoceros[sic] sp.).   Polyconoceras callosus(Karsch, 1881): Omine 1965b: table 1 (list; as Polyconcerus[sic] callosuesp[sic]).    Spirobolus joannisiBrölemann, 1896: Ikehara et al. 1974: table 1 (list; as  Spirobolus joannisu[sic]).     Prospirobolus joannise[sic]:  Ikehara and Shimojana 1975: 125, one text-fig.;  Kikunaga et al. 1993: 91(list);  Yokotsuka 2002: 242, one text-fig.;  Yokotsuka 2004: 242, one text-fig.;  Yokotsuka 2011: 242, one text-fig.    Acladocricussp.:  Omine et al. 1982: 119, 121, photo 5.    Spirobolussp.:  Takano 1989: 4, fig. 1;  Murakami 1993: 98(list); Tanabe 2001: frontispiece 5;  Omine 2002: 157, 161, table 5;  Chigira and Tanaka 2004: 16(list), photo 18; Tanabe in NCD Okinawa2005: 306; Takano in  Ministry of the Environment 2010: 5;  Nakamura and Korsós 2010: 79, 81 (list); Takano in Ministry of the Environment 2014: frontispiece 2, 56;  Shinohara et al. 2015: 981, one photo; Nakamura in NCD Okinawa2017: 36, one photo, 419;  Horii 2020: 122, one text-fig.   Diagnosis.The new species is characterized by the following combination of characteristics: coxa of anterior gonopods long and subtriangular; mesal sternal process of anterior gonopods pentagonal; prefemoral endite of posteri- or gonopods coronoid, distal end rounded, with mesal margin lacking notch; telopodite of posterior gonopods more than 2× longer than prefemoral endite; lateral flange of cyphopods with 4 serrations.   Material examined.   Holotype. KUZ Z4329( Fig. 1B–D), male, Mt. Omotodake( 24.41671°N, 124.19145°E), Ishigaki Island, Yaeyama Islands, Ryukyu Islands, Japan,  13 October 2020, col. Naoto Sawada( NS).    Paratypes. Fourspecimens from Ishigaki Island: KUZ Z4328, male, near the type locality ( 24.41608°N, 124.19150°E),  3 June 2019, col . Yuta Fujimori; KUZ Z4331– Z4333, three females, same data as for holotype.  Sixspecimens from Iriomote Island, Yaeyama Islands, Japan: KUZ Z4330, female, Mt. Tedo ( 24.37084°N, 123.82051°E), 21 October 2020, col . Minoru Anzai; KUZ Z4334, Z4335, Z4338, three males, and KUZ Z4336, female, near Mariudo Waterfall( 24.36030°N, 123.80045°E),  21 April 2022, col. NS; KUZ Z4337, female, near Yutsun Waterfall( 24.36721°N, 123.88435°E),  20 April 2022, col. NS.   Description.Adult males: 63.1–74.7 mmlong, vertical diameter of largest body ring 5.9–6.3 mm; body with 55–57 podous rings + telson. Adult females: 75.5–92.2 mmlong, vertical diameter of largest body ring 6.48–7.52 mm; body with 55–59 podous rings + telson.  Head. Head capsule ( Fig. 2A) smooth, area below antennal sockets with wrinkles. Occipital furrow reaching level of lower edge of antennal sockets. Incisura lateralis open. Labrum with 2 or 3 teeth, 5–8 supralabral setae, and 16–28 labral setae. Eye diameter ~0.75× greater than interocular space; with 7 or 8 vertical rows of ommatidia, 5 or 6 horizontal rows, and with 31–39 ommatidia per eye forming suboval cluster. Antennae ( Fig. 2D, E) short, reaching to posterior margin of collum, when stretched back accommodated in shallow furrow composed of horizontal segment in head capsule and vertical segment in mandibular cardo and stipes. Antennomere lengths II> I> III> V> VI> IV> VII; antennomere I and II glabrous, III with some ventral setae, IV sparsely setose, V, VI and VII densely setose, and V and VI with sensilla basiconica bacilliformia latero-apically ( Fig. 3A, B); with 4 apical sensilla. Mandibular stipes broad at base, apically gradually narrowed; subanterior margin of stipes mucronate. Gnathal lobe ( Fig. 2B) external tooth with 2 large and prominent cusps; inner tooth with 4 cusps; lateral tooth thin; 8 pectinate lamellae; molar plate with 15 transverse furrows. Gnathochilarium ( Fig. 2C) typically spirobolidan; each stipes with 3 apical setae; each lamella lingualis with 2 setae, one behind the other; basal part of mentum transversely wrinkled; basal part of stipes longitudinally wrinkled.  Collum. Surface smooth, with marginal furrow along lateral part of anterior margin; lateral lobes narrowly rounded, not extending as far ventrad as ventral margin of body ring 2 ( Fig. 4A).  Body rings. Surface very smooth, parallel-sided in dorsal view ( Fig. 1B, C). Prozona smooth. ‘Tergo-pleural’ suture visible on pro- and mesozona; mesozona ventrally with fine oblique striae, dorsally punctate; metazoa ventrally with fine longitudinal striae. ‘Pleural’ parts of rings with fine oblique striae. Sterna transversely striate. Pleurotergal tips of body ring 2 ( Fig. 4B) gaping ventrally, not connected to sternite; inner outline of pleurotergal tips of female body ring 2 viewed anteriorly nearly straight (upper part slightly convex, lower part concave slightly), with apex of pleural flange subpointed; pleurotergal tips of male body ring 7 fused ventrally. Ozopores present from body ring 6, situated in mesozona, ~1/4 pore diameter in front of metazoa ( Fig. 4A).  Telson. Entirely smooth; preanal ring tapering, not exceeding anal valves ( Fig. 4C). Anal valves impressed submarginally; margins slightly protruding, liplike. Subanal scale broadly triangular ( Fig. 4D).  Legs. Midbody leg length 76% of body diameter in holotypemale (leg-pair 15), 76% of body diameter in paratypefemale (KUZ Z4332: leg-pair 15). Prefemur basally constricted, femur longer than other podomeres ( Fig. 4H). Postgenital legs unmodified, with few ventral setae (e.g., 0-1, 0, 0-1, 0, 0-1, 1-2; leg-pairs 10, 15 and 20). Adhesive pads absent. Claw slender, ~1/3× longer than tarsus. First and second legs ( Fig. 4E, F) modified, coxae fused to sternites and greatly elongated. Coxae of male legs 3–7 with short rounded processes ( Fig. 4G).  Anterior gonopods. Mesal sternal process (mp) pentagonal, not reaching as far as coxal tip ( Fig. 5A, B). Coxa (co) long, subtriangular, apically gradually narrowed, rounded, with pronounced projection beyond sternal process ( Fig. 5A, B). Telopodite (tea) apically far overreaching coxa ( Fig. 5C, D); apex of telopodite hooklike, bending laterally ( Fig.  Fig. 3.  Spirobolus akamma sp. nov., paratype female (KUZ Z4332). A, Antennomere V of left antenna, latero-apical view, showing sensilla basiconica bacilliformia; B, antennomere VI of left antenna, latero-apical view, showing sensilla basiconica bacilliformia.  Fig. 4.  Spirobolus akamma sp. nov., paratype male (KUZ Z4328; A, E–G), paratype female (KUZ Z4332; B), and holotype male (KUZ Z4329; C, D, H). A, Head, collum and body rings 2–7, lateral view; B, body ring 2, anterior view; C, caudal end with porous rings + telson, lateral view (terminal four leg pairs removed); D, telson, ventral view (terminal four leg pairs removed); E, 1st leg pair, anterior view; F, 2nd leg pair, posterior view; G, 3rd leg pair, anterior view; H, left leg of 15th leg pair, anterior view.  Fig. 5.  Spirobolus akamma sp. nov., holotype male (KUZ Z4329), anterior gonopods. A, B, Anterior view; C, D, posterior view. Abbreviations: co, coxa of anterior gonopod; mp, mesal sternal process; tea, telopodite of anterior gonopod.  Fig. 6.  Spirobolus akamma sp. nov., holotype male (KUZ Z4329), left posterior gonopod. A, B, Anterior view; C, D, posterior view. Abbreviations: pe, prefemoral endite; tep, telopodite of posterior gonopod. 5A–D).  Posterior gonopods. Telopodite (tep) slender, more than 2× longer than prefemoral endite (pe) ( Fig. 6A–D); inner side of apex slightly concave, with or without tiny serrations ( Figs 6B, 7); outer side of apex slightly swollen; outer margin of telopodite with longitudinal groove ( Fig. 6D); prefemoral endite coronoid, with rounded distal end ( Fig. 6D).  Cyphopods. Cyphopods broad distally ( Fig. 8A, C); distallobe cephalic face without longitudinal groove ( Fig. 8A). Lateral flange (lf) narrow, with 4 serrations; 1st serration as large as 2nd at midpoint of flange; 4th serration at proximal end of flange smallest ( Fig. 8C). Valves (av and pv) prominent, of equal size ( Fig. 8B).  Coloration. In life, both anterior and posterior margins of collum and dorsoposterior margin of body rings 2 to preanal ring reddish, with remainder of body rings blackish ( Fig. 1A). Reddish color faded in ethanol.   Etymology.The specific name  akammais derived from the Yaeyama folk tale “ ẁDz” (Akamma means “red horse” and is the name of the horse beloved by the protagonist), and thus is treated as indeclinable.  DNA sequences and genetic distances. In total, seven sequences were obtained: paratypemale ( KUZ Z4328) from Ishigaki Island, three sequences, 28S (531 bp; INSDaccession number LC727543), COI (658 bp; LC727547) and 16S (431 bp; LC727545); paratypefemale ( KUZ Z4332) from Ishigaki, one sequence, COI (658 bp; LC727549); and paratypefemale ( KUZ Z4330) from Iriomote Island, three sequences, 28S (531 bp; LC727544), COI (658 bp; LC727548) and 16S (431 bp; LC727546). The paratypemale 28S sequence from Ishigaki and paratypefemale 28S sequence from Iriomote were identical; their 16S sequences revealed 4/431 (0.9%) base pairs to be polymorphic. The COI uncorrected p-distance between  S. akamma sp. nov.and  S. bungiiwas 12.8–13.4%, with the distance between  S. akamma sp. nov.and  Spirobolussp.11.7–12.7%. The COI divergence between  S. bungiiand  Spirobolussp.was 4.1%. Additionally, the COI genetic distance of our  S. akamma sp. nov.specimens was 0.2–0.9%. The low genetic divergence corroborates the taxonomic conclusion that  Spiroboluspopulations on Ishigaki and Iriomote islands are conspecific.   Distribution and habitat.  Spirobolus akamma sp. nov.occurs on Ishigaki and Iriomote islands in Yaeyama Islands; this species has been also recorded from Kohama Island, a small islet located between Ishigaki and Iriomote islands ( Chigira and Tanaka 2004). This species has been reported from terrestrial and arboreal habitats ( Ikehara and Shimojana 1975; Yokotsuka 2002; Shinohara et al. 2015), and most of our specimens were also collected from arboreal habitats.   Remarks.The new species clearly belongs to the genus  Spirobolusbecause it possesses the following diagnostic generic characteristics ( Keeton 1960; Hsu 2008): boat-shaped posterior gonopods; a short prefemoral endite of the posterior gonopods, being neither subrectangular nor as long as the telopodite of the posterior gonopods; and with thick cyphopods, with teeth on the lateral flange. A BLAST search ( Altschul et al. 1990) of partial COI sequences of  S. akamma sp. nov.(LC727547–LC727549) based on BLASTN 2.13.0+ ( Zhang et al. 2000) at the NCBI website (https://blast.ncbi.nlm.nih.gov/) revealed them to be mostly identical (87.1–87.7%; with 98% query coverage) to the sequence from the complete mitogenome of  S. bungii(NC_056899 = MT767838). BLAST results preliminarily corroborated our conclusion that  S. akamma sp. nov.is a member of  Spirobolus.  Fig. 7.  Spirobolus akamma sp. nov., holotype male (KUZ Z4329), apical part of right posterior gonopod, anterior view. Abbreviations: pe, prefemoral endite; tep, telopodite of posterior gonopod.  Fig. 8.  Spirobolus akamma sp. nov., paratype female (KUZ Z4332), left cyphopod. A, Anterior view; B, lateral view; C, posterior view, dashed lines indicate the lateral margins of serrations. Abbreviations: av, anterior valve; lf, lateral flange; pv, posterior valve.   Spirobolus akamma sp. nov.may be most morphologically similar to S.“lienhuachihus”, from Lienhuachih, central Taiwan, but it differs in possessing a pentagonal mesal sternal process of the anterior gonopods, and a lateral flange on the cyphopods with 4 serrations [ S.“lienhuachihus” has a concave mesal sternal process of the anterior gonopods, and cyphopods with a lateral flange with 5–7 serrations ( Hsu 2008)]. Although the new species shares most characteristics of the posterior gonopods with  S. grahami Keeton, 1960, which is endemic to Sichuanand Guizhouin southwest China, the former is distinguishable from the latter by having the telopodite of the posterior gonopods more than 2× longer than the prefemoral endite of the posterior gonopods [in  S. grahami, the telopodite is less than 2× the length of the prefemoral endite ( Keeton 1960)]. While  S. akamma sp. nov.and  S. walkeriPocock, 1895share general features of the cyphopods, the new species differs from it in the number of serrations of lateral flange of cyphopods ( 4 in  S. akamma sp. nov.vs. 3 in  S. walkeri; Keeton 1960). The distribution of S. f.“semiflavus” includes the northeastern part of Taiwan, and is thus most geographically close to  S. akamma sp. nov.( Hsu 2008). However, S. f.“semiflavus” is unequivocally distinguishable from  S. akamma sp. nov.by gonopodal and cyphopodal features. The morphological features of  S. akamma sp. nov.coincide with the Takano’s (1989)description of  Spirobolussp.from Yaeyama Islands. In anterior gonopod morphology,  S. akamma sp. nov.is also similar to “  Polyconocerassp.” from the Yaeyama Islands as described by Omine (1965a). We posit that these previously reported “Yaeyama-maruyasude” are conspecific with  S. akamma sp. nov. 2020-10-13 KUZ, NS Naoto Sawada Japan Ryukyu Islands 24.41671 Mt. Omotodake 1 124.19145 Yaeyama Islands 2 25 Z4329 1 holotype 2019-06-03 KUZ 24.41608 Four 1 124.1915 Ishigaki Island 2 25 Z4328 1 paratype 2020-10-13 KUZ Naoto Sawada Japan Ryukyu Islands 24.41671 Yuta Fujimori 1 124.19145 Yaeyama Islands 2 25 Z4331, Z4333 1 1 paratype KUZ Mt Japan Yaeyama Islands Six Iriomote Island 2 25 Z4330 1 paratype 2022-04-21 KUZ Mariudo Waterfall Japan 24.3603 Minoru Anzai 1 123.80045 2 25 Z4334, Z4335, Z4338, Z4336 1 1 paratype 2022-04-20 KUZ Japan 24.36721 Yutsun Waterfall 1 123.88435 2 25 Z4337 1 paratype KUZ, INSD Ishigaki Island Iriomote Island 5 28 Z4328, LC727547, LC727545, Z4332, LC727549, Z4330, LC727544, LC727548, LC727546 3 paratype