Rhopalomeris sauda Nguyen & Sierwald & Marek 2019, new species

(Figs. 40–43)

Material examined. Holotype: male (IEBR–Myr 533H) Vietnam, Bac Kan Province, Ba Be National Park, forest on limestone, elevations of 400–500m, 10–11 July 2013, coll. Anh D. Nguyen.

Paratypes: 2 males, 3 females (IEBR–Myr 533P) same data as for holotype; 4 males, 3 females (IEBR–Myr 654) Vietnam, Vinh Phuc Province, Phuc Yen Town, Ngoc Thanh Commune, MeLinh Station for Biodiversity, 21.3850°N, 105.7119°E, 5 August 2017, coll. Anh D. Nguyen.

Other materials: 1 male, 2 females (FMNHINS 3716094), 3 males, 2 females (FMNH INS 3716073) 2 males, 2 females (FMNH INS 3716075) Vietnam, Vinh Phuc Province, Phuc Yen town, Ngoc Thanh commune, MeLinh Station for Biodiversity, 21.3850°N, 105.7119°E, regenerated forests, 10–16 September 2016, coll. P. Sierwald et al.; 1 female (FMNH INS 3716130) Vietnam, Vinh Phuc Province, Tam Dao district, Tam Dao NP, TV tower trail, natural forests, N21.460945°, E105.647021°, 17 September 2016, coll. P. Sierwald et al.

Etymology. The Vietnamese name “Sâu đá”, refers to pill millipedes (noun in apposition).

Diagnosis. The species is easily recognised by terga being mostly yellowish, with two close paramedian marbled blackish, large spots, and two distolateral small black spots; syncoxial lobe of telopod slightly concave medially or round; syncoxial horns directed ventrad, higher than lobe; telopods with a large, tuberculiform, femoral process; tibia with a long, sigmoid mesad, acute process, and seta in middle. The new species differs from R. variegata Golovatch & Semenyuk, 2016 from the Highlands of Vietnam in colouration (yellow colour plus several black spots vs variegated colour). Another species, R. tonkinensis Silvestri, 1917, was described from female specimens, the male remains unknown. However, the new species is clearly distinguishable from R. tonkinensis in colour pattern (mostly yellow plus several black spots vs. mostly black in R. tonkinensis). The number of ocelli differs between the species (7+ 1 in R. sauda vs 8+ 1 in R. tonkinensis).

Description. Holotype male (IEBR–Myr 533H). Width of 2nd tergum 6.0 mm, body length 11.0 mm.

Exoskeleton (Figs. 40, 41): Terga black, with four lateral light-brown reniform spots, and a medioposterior, lightyellow triangular spot. Anal shield black, with a thin, medial yellow line; caudal and lateral margins yellow. Thoracic shield with similar colour pattern to other terga.

Head: Ocelli 7+1, lenses convex, black contrasting against light-brown background of head. Tömösváry organ transverse strongly horseshoe-shaped. Antenna clavate (Fig. 41F). Antennomere 6 largest and longest, 2.5–3.0× long as wide. Antennal tip with numerous apical sensory cones. Tergites: Collum semicircular, light yellow, with a marbled yellowbrown, transverse oval spot in the middle, with two transverse striae (Fig. 41C). Second tergum with a narrow hyposchism, not reaching caudal margin, and with 2–3 striae; other terga with 2–3 striae distolaterally. Anal shield rounded, not concave medio-caudally (Fig. 41C). Legs: Leg-pair 17 (Figs. 42A, 43A) strongly reduced, with 4 podomeres, with a high, regularly rounded outer coxal lobe; coxa with an apical setiferous spine; podomore 4 with two apical setae. Leg-pair 18 (Figs. 42B, 43B) strongly reduced as legs of leg-pair 17, with 4 podomeres, with a simple syncoxial notch (see arrow).

Telopods (Figs. 42C, D, 43D, 44) with a trapeziform, slightly convex medially or round, sparsely setose, central syncoxial lobe with two setiferous horns, each directed ventrad, longer than syncoxial lobe (Figs. 42C, D, 44D). Prefemur and femur with long trichosteles (Fig. 44C). Prefemur without additional processes. Femur with large, tuberculiform process present, distal part bowed and acuminate apically. Tibia with a long, sigmoid mesad, acute tuberculiform process, and seta in medially. Tarsus slightly sigmoid anteriomesad, subacuminate apically (Figs. 42C, D, 44A – C).