Xystodesmus saltuosus ( Haga, 1968 ), 2025

Xystodesmus saltuosus ( Haga, 1968) comb. nov.

Fig. 14 A – C View Figure 14

Rhysodesmus saltuosus Haga, 1968: 8, fig. 11 a – f: Mt Sarakura-yama, Kita-Kyushu City, 18 June 1961, leg. A. Haga

Type material examined.

Holotype male ( NSMT -My.162 ).

Redescription.

Length not possible to measure (holotype is in 5 pieces), but apparently under 30 mm, midbody width with paraterga 4.8 mm, midbody metatergal length 1.2 mm, collum width 4 mm, median collum length 1.9 mm. Body sides between segments 7–14 subparallel.

Head smooth, with two frontal setae, epicranial suture distinct. Antennal articles slightly clavate, first article sub-globose, articles 2–6 subequal in length, article 7 small, as long as wide.

Collum in dorsal view subtrapezoidal, no traces of marginal ridges, lateral corners rounded, directed posterio-ventrad, posterior margin slightly wavy. Pro- and metaterga smooth, transverse depression on metaterga hardly noticeable. Anterior edges of all paranota rounded, posterio-lateral corners increasingly pointed caudad, from segment 5 onwards with a concave posterior excision. Lateral sides of paranota arched, those bearing pores depressed, pore formula normal.

Segments 15–19 gradually tapering, caudal corners increasingly pointed. Epiproct in dorsal view triangular, in lateral view slightly curved ventrad, with 2 + 2 apical and 4 + 4 lateral setae all on strong tubercles; paraprocts smooth, with two pairs of setae, upper ones on margins, lower ones on sides; hypoproct semicircular with 1 + 1 setae on small tubercles.

Bases of midbody leg pairs well separated by 1.0 mm, sterna smooth and wide, pro- and metasterna well separated. Coxa sub-globose; prefemur ~ 1.2 × longer, with well-developed ventral spine on postgonopodal legs; femur incrassate, ~ 2 × as long as wide; postfemur much shorter, approximately as long as wide, tibia and tarsus slender, subequal in length, ~ 2 × as long as wide; claw large, flat, curved ventrad.

Colour of living specimens unknown; holotype completely faded due to preservation, currently yellow, and even pro- and metatergal differences cannot be traced.

Male sexual characters. Second leg pair with small coxal processes with a pair of strong setae (as in X. rebekae sp. nov., Fig. 7 C View Figure 7 ), sterna of segments 4–6 and leg pairs 3 onwards without any modification. Gonopod (Fig. 14 A – C View Figure 14 ) coxa long and slender, ~ 2 × as long as wide, coxal apophysis completely lacking, apophyseal macroseta relatively small. Telopodite built of three subequal, subparallel processes: prefemoral process (pfp) sits on short, densely setose prefemur; approximately as long as acropodite, curved distad at its end; solenomere has two processes, acropodite (a) subparallel-sided, flattened, tip rectangular as if cut off, prostatic groove runs along mesal side; and at its base, from the femoral part a third process (fp) starts, slightly shorter than acropodite, gradually tapering towards long, pointed tip.

Female unknown.

Remarks.

Rhysodesmus is a Middle American genus, and the name was mistakenly used by early Japanese authors, mainly following the prominent Japanese myriapodologist Yoshioki Takakuwa (1873–1960). The situation was first explained in Japanese by Shinohara (1977), but also established by Hoffman (1980), Marek et al. (2014), and Huerta-de la Barrera et al. (2021). The species itself ( Rh. saltuosus ) was unfortunately overlooked by Shinohara (1977), Tanabe and Shinohara (1996), and Marek et al. (2014) since it was published in a private but widely available publication ( Haga 1968). Huerta-de la Barrera et al. (2021) referred to Haga’s publication, but did not specifically mentioned Rh. saltuosus . Since the holotype male was available for study we could establish its association with Xystodesmus and removed the species from Rhysodesmus .