Sphaerobelum laoticum, Wesener, 2019

Wesener, Thomas, 2019, First records of giant pill-millipedes from Laos (Diplopoda, Sphaerotheriida, Zephroniidae), Zootaxa 4563 (2), pp. 201-248 : 233-238

Sphaerobelum laoticum new species

Figures 6I , 23 , 24 .

Material examined: Type material. 1 M holotype (SMF) from Laos, Vientiane Province, Vang Vieng, W. of Nam Song (N18°55'46.86", 102°20'56.82"E), 324 m, Tham Nam Or Khem, in cave, leg. by hand, 28.VII.2014, P. Jäger & S. Münnich.

Other material examined: 1 imm. M (SMF) from Laos, Vientinae Province, Van Vieng, Ban Sok Say (N19°1'20.30", 102°26'54.11"E), 295 m, in vegetation, leg. by hand, P. Jäger & S. Packheiser, 23.VII.2018. 1 imm. F ( SMF) from Laos, Vientinae Province , Van Vieng , N of Ban Phoxay , Tham Hoi and Tham Loup, in cave (N19°02.350', 102°25.423'E), 256 m, leg. by hand, P. Jäger & S. Packheiser, 23.VII.2018 .

Diagnosis: S. laoticum n. sp. belongs to a group of Sphaerobelum species in which the mesal margin of the femur is unmodified ( Fig. 23B ). S. laoticum n. sp. shares only with S. hirsutum , S. clavigerum , S. nigrum n. sp., S. splendidum n. sp. and S. schwendingeri n. sp. the presence of a "hook" at telopoditomere 4 of the posterior telopods ( Figs 24E, F ). S. laoticum n. sp. differs from S. hirsutum in the presence of glabrous tergites, from S. clavigerum in the presence of a short locking carina on the anal shield. It differs from S. nigrum n. sp. in the presence of a cylindrical antennomere 6, the presence of only 5–7 ventral spines on the tarsi (8–10 in the other species) ( Fig. 23B ), and the presence of a strongly curved telopoditomere 4 of the posterior telopod, all characters only shared with S. splendidum n. sp. and S. schwendingeri n. sp. For a differentiation of S. laoticum n. sp. with S. splendidum n. sp. see above. S. laoticum n. sp. differs from S. schwendingeri n. sp., which occurs almost in sympatry, in a genetic distance of 13.6% in the COI gene, the process of telopoditomere 2 of the anterior telopods projecting as high as basal 1/3 (3/ 4 in S. schwendingeri n. sp.) of telopoditomere 3+4 ( Fig. 22F ); anal shield with a single short locking carinae (absent in S. schwendingeri n. sp.); palpi of gnathochilarium, sensory cones located in single field (in several clusters in S. schwendingeri n. sp.).

Description: Based on male holotype

Measurements: body length 24.4 mm. Width, of thoracic shield = 12.7 mm (= widest). Height, of thoracic shield = 7.4 mm (= highest). Coloration: Head and collum black. Tergites black (fading to brown in longer preserved specimens), paratergite depressions olive green ( Fig. 6I ). Antennae and legs red.

Head: with ca. 65 ocelli. Antennae extending posteriorly to leg 5. Size of antennomeres 1=2=3=4=5<<6, 6th apically widened. Apical disc carrying 81/86 apical cones. Antennomere 1–5 with only few setae. Organ of Tömösváry located in antennal groove. Gnathochilarium: with the usual shape for the order, sensory cones located in single field. Mandibles: not investigated.

First stigmatic plate: small, well-rounded, inconspicuous, slightly curved towards coxa ( Fig. 23A ).

Laterotergites: 1 and 2 with a short, well-rounded projection. Collum: glabrous only short setae at margin. Thoracic shield: Shallow grooves with few setae, surface glabrous. Margin towards grooves with three or four weak anterior, and 2 or 3 posterior crests. Tergites: shiny, polished, no pits or setae present in posterior 2/3. Anterior 1/3, which is mainly visible when the specimen is rolled up, with longer setae providing a golden sheen. Paratergite tips weakly projecting posteriorly ( Fig. 6I ). Endotergum: inner section without any setae or spines. Middle area with a single row of sparse elliptical, cuticular impressions, distance between impressions larger than their diameter. Apically 3 dense rows of short marginal bristles, the longest just protruding up to tergal margin. Bristles not smooth, but with numerous small spicules. Anal shield: well-rounded, covered with numerous tiny setae, underside with a single very small, almost dot-like, locking carina. Legs: leg-pair 1 with 2 ventral spines, leg-pair 2 with 4, leg-pair 3 with 6, leg-pairs 4–21 with only 4–7. Apical spines at present tarsi 3–21. In leg 9, femur 1.6 times, tarsus 3.9 times longer than wide ( Fig. 23B ). Leg 1 without a coxal process ( Fig. 23A ), leg 2 with a sharp coxal process ( Fig. 24A ), while the process is well-rounded in the following legs.

Male sexual characters: male gonopore large, covered by small, inconspicuous plate ( Fig. 24A ). Anterior telopods ( Figs 24 B–D): consisting of three telopoditomere above syncoxite. Last telopoditomere divided by a suture still visible in lateral view. Telopoditomere 1 rectangular, slightly longer than wide. Telopoditomere 2 large, as long as telopoditomere 3. Process of telopoditomere 2 located posteriorly, not visible in anterior view. Process of telopoditomere 2 wide, projecting to half of telopoditomere 3, slightly curved, apically with a sharp tip. Telopoditomere 3 massive, cylindrical, straight, apically slightly tapering. Posterior side with two large, triangular spines. In anterior view all telopoditomeres covered by long setae, in posterior view telopoditomeres 2 and 3 only with marginal setae. Posterior telopods ( Figs 25E, F ): telopoditomere 1 rectangular, slightly longer than wide. Immovable finger (process of telopoditomere 2) slightly shorter than movable finger, consisting of telopoditomeres 3 and 4. Immovable finger with a characteristic, distally swollen apex, slightly swollen. Apically broader than base, at tip in anterior view with a few large, crenulated teeth. Telopoditomere 3 elongated, towards immovable finger at midpoint with a triangular extension carrying a spines. Telopoditomere 4 tapering, anterior half strongly curved 90° towards immovable finger, which it overlaps. At inner margin with two larger spines. Entire telopoditomeres 1 and 2 on both sides covered with long setae, except for the immovable finger. Telopoditomere 3 only basally in anterior view with setae, remaining part as well as telopoditomere 4 glabrous.

Intraspecific variation: S. laoticum n. sp. is the giant pill-millipede species from Laos with the most known localities (3, all in a 15 km radius, Fig. 5 ) and specimens. The specimens from the different localities show considerable intraspecific variation. The smaller, not fully mature specimens from Ban Sok Say and Tham Loup display one, sometimes two weak short locking carinae. These samples were collected recently and might require Nagoya permissions to be barcoded, so an analysis of the intraspecific variation between these populations was not possible.

Remarks: This species, only known from males, lives syntopically with two other Sphaerobelum species, one only known from females. Sphaerobelum sp. L10, and S. schwendingeri ( Fig. 5 , see below). Genetic barcoding data clearly reveals that the specimens, collected from a close-by location, are distinct species, differing in 15.9% (to S. sp. L10) or 13.6 % p-distance (to S. schwendingeri n. sp.) in the COI gene in the barcoding COI gene.

Derivatio nominis: laoticum, noun in apposition, after Laos, as this is the first Sphaerobelum known from this country.

Figures

FIGURE 5. Distribution map of Sphaerobelum species, including the unnamed females.

FIGURE 6. Habitus multi-layer stacked photographs of Sphaerobelum species. A: Sphaerobelum bolavensis n. sp.; B: Sphaerobelum phouloei n. sp.; C: Sphaerobelum denticulatum n. sp.; D: Sphaerobelum spinatum n. sp.; E: Sphaerobelum lachneeis n. sp.; F: Sphaerobelum peterjaegeri n. sp.; G: Sphaerobelum nigrum n. sp.; H: Sphaerobelum splendidum n. sp.; I: Sphaerobelum laoticum n. sp. Not to scale.

FIGURE 22. Sphaerobelum splendidum n. sp., holotype (SMF); A: coxa of first left leg with first stigmatic plate; B: 9th left leg; C: coxa of second left leg with gonopore; D: left anterior telopod, anterior view; E: left anterior telopod, posterior view; F: left anterior telopod, lateral view; G: right posterior telopod, anterior view; H: right posterior telopod, posterior view. Abbreviations: Cx = coxa; St-Pl = stigmatic plate; Syn-Cx = syncoxite. Scale bars = 1 mm.

FIGURE 23. Sphaerobelum laoticum n. sp., holotype (SMF); A: coxa of first left leg with first stigmatic plate; B: 9th left leg. Abbreviations: Cx = coxa; St-Pl = stigmatic plate. Scale bars = 1 mm.

FIGURE 24. Sphaerobelum laoticum n. sp., holotype (SMF); A: coxa of second left leg with gonopore; B: left anterior telopod, anterior view; C: left anterior telopod, posterior view; D: left anterior telopod, lateral view; E: left posterior telopod, anterior view; F: left posterior telopod, posterior view. Abbreviations: Cx = coxa; Syn-Cx = syncoxite. Scale bars = 1 mm.

FIGURE 25. Sphaerobelum schwendingeri n. sp. A–C female paratype (ZMUC), D–G male holotype (MHNG). A: coxa of first right leg with first stigmatic plate; B: 9th left leg; C: coxa and prefemur of second leg with vulva; D: left anterior telopod, anterior view; E: left anterior telopod, posterior view; F: right posterior telopod, anterior view; G: right posterior telopod, posterior view. Abbreviations: Cx = coxa; O = operculum of vulva; Pre = prefemur; St-Pl = stigmatic plate; Syn-Cx = syncoxite. Scale bars = 1 mm.