Sphaerobelum denticulatum, Wesener, 2019

Wesener, Thomas, 2019, First records of giant pill-millipedes from Laos (Diplopoda, Sphaerotheriida, Zephroniidae), Zootaxa 4563 (2), pp. 201-248 : 216-221

Sphaerobelum denticulatum new species

Figures 6C , 13

Material examined: 1 M holotype ( MHNG LT-10/12) from Laos, Oudomxai Province, ca 3 km E of Tad Lak 11, SE of Oudomxai city (= Muang Xai) (N20°36'20"; 102°01'16" E), 1020 m, undisturbed evergreen hill forest, leg. 18.IX.2010, P. Schwendinger .

Diagnosis: S. denticulatum n. sp. belongs to a group of Sphaerobelum species in which the mesal margin of the femur is extended with several teeth ( Fig. 13A ). S. denticulatum n. sp. shares only with S. phouloei n. sp. a curved telopoditomere 4 of the posterior telopods which overlaps the immovable finger ( Figs 13D, E ). See above for a separation of these two species.

Description. Measurements: Body length: length ca 22.7 mm. Width, of thoracic shield = 11.5 mm (= broadest). Height, of thoracic shield = 6.3 mm, tergite 7 = 6.9 mm (= highest). Coloration: in preserved specimens tergites black, thoracic shield grooves and paratergite depressions dark green. Head and collum black ( Fig. 6C ). Antennae dirty green, antennomere 6 yellow. Legs light brown, tarsus darker.

Head: Eyes with ca. 55 ocelli. Antennae short, extending back to leg 3, with rounded joints. Lengths of antennomeres: 1>2=3=4=5<<6, 6 as large as 3–5 combined. All antennomeres densely pubescent, sensilla basiconica surrounding apical disc. Last antennomere thickened, cylindrical. Apical disc with 68/74 apical cones. All antennomeres covered by long setae. Organ of Tömösváry located inside antennal groove. Gnathochilarium: structure typical of the order. Palpi sensory cones located in single field. Mandibles: not dissected.

Stigmatic plates: first stigmatic plate rounded, apex well-rounded, straight towards coxa 1. Laterotergites: 1 and 2 with a short, well-rounded projection. Collum: with glabrous surface, margins with few isolated setae. Thoracic shield: surface glabrous, surface chagrinated unlike tergites, setae only in grooves. Shallow grooves beset with numerous long setae, slope towards groove with 2 or 3 weak anterior and 2 or 3 posterior keels.

Tergites: glabrous, but entirely covered by tiny pits. Tips of paratergites of midbody tergites projecting posteriorly ( Fig. 6C ). Endotergum: inner section lacking any spines or setae. Middle area with a single row of small, circular cuticular impressions. Distance between impressions as wide as their diameter. Apically, 1–2 sparse rows of short marginal bristles, ending well before tergite margin. Bristles not smooth, but with numerous small spinicles. Anal shield: slightly bell shaped, surface sparsely covered by tiny setae each standing in a tiny pit. Underside with a single, black locking carina, located close to tergite margin. Locking carinae 3x size of those of tergites. Legs: legpair 1 with 3 or 4 ventral spines, leg-pair 2 with 5, leg-pair 3 with 6 or 7. First two leg-pairs without an apical spine. Leg-pairs 4–21 with 10 or 12 ventral spines and one dorso-apical spine. In leg 9 femur 1.2 times, tarsus 3.7 times longer than wide ( Fig. 13A ). All podomeres densely setose. Coxa with a large and marginally toothed process. Coxa process absent at first leg and sharply projecting at second. Prefemur at apical margin with a projection laterally and mesally. Lateral projection triangular and sharply edged, juxtaposed to coxal process. Femur extended mesally into a dentate margin featuring 12–14 teeth. Prefemur also with ca. 6 teeth.

Female unknown.

Male sexual characters: gonopore covered with a single, undivided, circular, sclerotized plate. Anterior telopods ( Figs 13B, C ): consisting of 4 telopoditomeres above syncoxite. Telopoditomere 1 rectangular, as long as wide. Telopoditomere 2 large, almost as long as telopoditomere 3 and 4 combined. Process of telopoditomere 2 located posteriorly, visible mesally and apically in anterior view. Process wide, projecting to half of telopoditomere 4, apically with a well-rounded tip. Telopoditomere 3 cylindrical, straight, slightly shorter than telopoditomere 4. Telopoditomere 4 cylindrical, well-rounded, posterior side with a black sclerotized spot and three small, triangular spine. Telopoditomeres 1–4 in anterior view covered with long setae. In posterior view all telopoditomeres with fewer setae. Posterior telopods ( Figs 13D, E ): telopoditomere 1 slightly longer than wide. Immovable finger (process of telopoditomere 2) longer than movable finger, consisting of telopoditomeres 3 and 4. Immovable finger with a characteristic, distally swollen apex, well rounded, apex therefore wider than base. Immovable finger in anterior view with a large spine, at tip opposite to tip of telopoditomere 4 with sclerotized spots. Telopoditomere 3 rectangular, towards immoveable finger with a triangular expansion carrying two spines. Telopoditomere 4 reaching 2/3 of length of telopoditomere 3, much more slender, apically strongly tapering into acute tip, curved towards immovable finger. Inner margin with single spine towards immovable finger. Telopoditomere 1 at both sides covered by setae. Telopoditomeres 2 and 3 in anterior view covered by long setae, in posterior view mostly glabrous. Telopoditomere 4 only with marginal setae.

Derivatio nominis: denticulatum, noun in apposition, after the dentate mesal margin of the femur and prefemur.

Figures

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 13. Sphaerobelum denticulatum n. sp., holotype (MHNG); A: 9th left leg; B: left anterior telopod, anterior view; C: left anterior telopod, posterior view; D: left posterior telopod, anterior view; E: left posterior telopod, posterior view. Abbreviations: Cx = coxa; Syn-Cx = syncoxite. Scale bars = 1 mm.