Sphaerobelum bolavensis, Wesener, 2019

Wesener, Thomas, 2019, First records of giant pill-millipedes from Laos (Diplopoda, Sphaerotheriida, Zephroniidae), Zootaxa 4563 (2), pp. 201-248 : 212-215

Sphaerobelum bolavensis new species

Figures 6A , 7 , 8 , 9A , 10 .

Material examined: Type specimens. 1 M holotype (ZMUC00040256) from Laos, Champasak Province, Bolaven Plateau, Ban Houayteuay, 1200 m (N 15°4.655', E 106°16.848') disturbed montane forest, leg. 10.XII.2007, by hand, S. Tarasov. 1 F paratype (ZFMK MYR8100), same data as holotype.

Non-type material: 1 F (MHNG LT-10/24) from Laos, Champasak Province, Bolaven Plateau, 3 km S of Ban Nong Luang, Tad Kameud, 1270 m (N 15°04'23", 106°12'36" E), undisturbed evergreen hill forest, 1.X.2010, leg. P. Schwendinger.

Diagnosis: S. bolavensis n. sp. belongs to a group of Sphaerobelum species in which the mesal margin of the femur is extended and apically tipped with several teeth ( Fig. 8A ). Sphaerobelum bolavensis n. sp. and S. bicorne from Vietnam are the only species with an extension only in the apical part of the femur. Sphaerobelum bolavensis n. sp. possesses a female vulval operculum only projecting in a single mesal process ( Fig. 8B ); in contrast, S. bicorne has two processes. Sphaerobelum bolavensis n. sp. has a telopoditomere 4 of the posterior telopod straight, apically without a recessed hook ( Figs 10E, F ); in contrast S. bicorne possesses a hook. Sphaerobelum bolavensis n. sp. has a short locking carina on the anal shield; whereas the carina is long in S. bicorne .

Description. Based on holotype male and paratype female.

Measurements: Holotype male. Body length ca 32.9 mm. Width, of thoracic shield = 14.2 mm, of tergite 8 = 14.9 mm (= broadest). Height, of thoracic shield = 7.1 mm, of tergite 7 = 8.2 mm (= highest). Female: body length = ca 28.8 mm. Width, of thoracic shield = 12.6 mm, of tergite 8 = 13.6 mm (=broadest). Height, of thoracic shield = 7.6 mm, of tergite 7, 8.3 mm (= highest). Coloration: in preserved specimens dark green, tergites with black posterior margin. Head and collum chestnut brown. Antennae orange, legs brown ( Fig. 6A ).

Head: Eyes with>70 ocelli. Aberrant ocellus located inside antennal groove. Antennae short, with rounded joints, extending posteriorly to leg-pair 3. First antennomere with cuticular scales ( Fig. 7A ). Lengths of antennomeres: 1>2=3=4=5<<6 ( Fig. 7A ). All antennomeres densely pubescent, sensilla basiconica surrounding apical disc. Shape of antennae sexually dimorphic, cylindrical in female; thickened, apically widened and slightly flattened in male ( Fig. 7B ). Apical disc with ca 47/52 apical cones (male) ( Fig. 7B ) or 30/32 (female). Apical cone shape typical of Diplopoda ( Fig. 7B ). Organ of Tömösváry located inside antennal groove. Gnathochilarium: structure typical of the order. Palpi with sensory cones arranged in clusters. Mandibles not dissected.

Stigmatic plates: first stigmatic plate widely rounded, apex well-rounded, weakly curved towards coxa 1. Laterotergites: laterotergite 1 strongly projecting into a sharp tip. Laterotergite 2 with a broad, stout, much shorter projection. Collum with glabrous surface, margins with few isolated setae. Thoracic shield: surface glabrous unlike tergites, setae only in grooves. Shallow grooves beset with numerous long setae, sloped towards groove with 9 continuous anterior and posterior keels. Tergites: surface densely setose with short setae. Tips of paratergites of midbody tergites projecting posteriorly. Endotergum: inner section lacking any spines or setae. Middle area with a single row of large, sparse, elliptical, cuticular impressions. Distance between impressions twice as wide as their diameter. Apically, 2 dense rows of long marginal bristles, their tips slightly protruding beyond tergal margin ( Fig. 9A ). Bristles not smooth, but with numerous small spicules. Anal shield: large, sexually dimorphic: in female weakly bell-shaped, in male strongly bell-shaped. Surface in both sexes completely covered by tiny setae. Underside with a single, short, black, locking carina, the latter located close to last laterotergite. Legs: leg-pair 1 with 2 ventral spines, leg-pair 2 with 4, leg-pair 3 with 5 or 6. First two leg-pairs without an apical spine. Leg-pairs 4–21 with 7–9 ventral spines and one dorso-apical spine. In leg-pair 9, femur 1.3 times, tarsus 4 times longer than wide ( Fig. 8A ). All podomeres densely setose. Coxa with a large and well-rounded process. Coxal process absent on leg-pair 1 and 2. Prefemur apico-mesally with a weak projection. Femur in apical part extended mesally into a dentate margin tipped with 4–6 teeth.

Female sexual characters: vulva large, covering 2/3 of coxa, extending mesally to anterior third of prefemur ( Fig. 8B ). Operculum rounded, very slightly invaginated medially, mesal margin strongly projecting into a wellrounded lobe twice as long as operculum. Subanal plate: damaged.

Male sexual characters: gonopore covered with a single, undivided, circular, sclerotized plate ( Fig. 10A ). Anterior telopods ( Figs 10 B–D): consisting of only 3 telopoditomeres above syncoxite. Telopoditomeres 3 and 4 apparently fused. Telopoditomere 1 rectangular, as long as wide. Telopoditomere 2 large, half as long as telopoditomere 3. Process of telopoditomere 2 located posteriorly, visible in anterior view; process slender, projecting to half length of telopoditomere 3. Process of telopoditomere 2 conspicuously 'hooked' apically with a sharp tip. Telopoditomere 3 massive, cylindrical, straight, apically slightly tapering; posterior side with a black sclerotized spot and a small, triangular spine. Telopoditomere 1 in apical view covered with long setae. In posterior view all telopoditomeres almost glabrous. Posterior telopods ( Figs 10E, F ): telopoditomere 1 short, half as long as wide. Immovable finger (process of telopoditomere 2) shorter than movable finger, consisting of telopoditomeres 3 and 4. Immovable finger with a characteristic distally swollen apex; well rounded, apex therefore twice as wide as base. Telopoditomere 3 rectangular, well rounded. Telopoditomere 4 as long as but slightly slenderer than telopoditomere 3. Telopoditomere 4 2.7 times longer than wide; apically weakly tapering, very slightly curved towards immovable finger. Telopoditomere 1 at both sides covered by setae, remaining telopoditomeres in posterior view almost glabrous, in anterior view with few isolated setae except for immovable finger which is more densely setose.

Remarks: This species occurs in syntopy with a female of an undetermined species, Zephroniidae sp. L04b (see below).

Derivatio nominis: bolavensis, noun in apposition, from the Bolaven plateau in Laos where this species was discovered ( Fig. 5 ).

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 7. Sphaerobelum bolavensis n. sp., holotype (ZMUC), left antenna, SEM, A: lateral view; B: apical disc with sensory cones. Abbreviations: d = apical disc; sb = sensilla basiconica; sc = sensory cones; numbers refer to antennomere number.

FIGURE 8. Sphaerobelum bolavensis n. sp., female paratype (ZFMK MYR8100); A: 9th left leg; B: coxa and prefemur of second leg with vulva. Abbreviations: Cx = coxa; O = operculum of vulva; Pre = prefemur. Not to scale.

FIGURE 9. Endoterga of the body ring 9 of different Sphaerobelum species. A: Sphaerobelum bolavensis n. sp.; B: Sphaerobelum phouloei n. sp.; C: Sphaerobelum spinatum n. sp.; D: Sphaerobelum splendidum n. sp. Abbreviations: cp = cuticular patterns; iA = inner area.

FIGURE 10. Sphaerobelum bolavensis n. sp., holotype (ZMUC); A: coxa of second left leg with gonopore; B: right anterior telopod, anterior view; C: right anterior telopod, posterior view; D: right anterior telopod, lateral view; E: left posterior telopod, anterior view; F: left posterior telopod, posterior view. Abbreviations: Syn-Cx = syncoxite. Scale bars = 1 mm.