Sphaerobelum peterjaegeri, Wesener, 2019

Wesener, Thomas, 2019, First records of giant pill-millipedes from Laos (Diplopoda, Sphaerotheriida, Zephroniidae), Zootaxa 4563 (2), pp. 201-248 : 227-229

Sphaerobelum peterjaegeri new species

Figures 6F , 19

Material examined: 1 M, holotype ( SMF SD553 ) from Laos, Luang Prabang Province, SE Luang Prabang, Nam Khan, Ban Pak Bak, Houay Kho , 328 m, (N19°44'09.1", 102°16'37.5"E), bank of stream, under stone, moist sand and gravel, leg. 28.II.2008, P. Jäger .

Diagnosis: S. peterjaegeri n. sp. belongs to a group of Sphaerobelum species in which the mesal margin of the femur is unmodified ( Fig. 19B ). S. peterjaegeri n. sp. shares only with S. separatum , S. truncatum and S. lachneeis n. sp. the absence of a "hook" at telopoditomere 4 of the posterior telopods ( Figs 19G, H ). S. peterjaegeri n. sp. differs from S. separatum in the absence of a lateral extension on podomere 3 of the anterior telopod, as well as the absence of an incurved process on telopoditomere 4 of the posterior telopods. S. peterjaegeri n. sp. is very similar to S. truncatum , but differs in several characters: <70 apical cones on the antenna (> 80 in S. truncatum ), antennae and legs orange-red (yellow in S. truncatum ), femur 1.7 times longer than wide (2.0 times longer than wide in S. truncatum ).

Description. Measurements: Body length: holotype male: length ca 23.8 mm. Width of thoracic shield = 11.6 mm (= broadest). Height of thoracic shield = 6.9 mm (= highest). Coloration: in preserved specimens brown to orange ( Fig. 6F ). Collum dark olive brown, same as head. Antennae and legs orange.

Head: Eyes with ca. 60 ocelli. Aberrant ocellus located inside antennal groove. Antennae short, with rounded joints, extending posteriorly to leg-pair 3. First antennomere with cuticular scales. Lengths of antennomeres: 1=2=3=4=5<<6. Shape of apical joint thickened, apically widened. Apical disc with ca 66/68 apical cones. Organ of Tömösváry located inside antennal groove. Gnathochilarium: structure typical of the order. Palpi with sensory cones arranged in a single field. Mandibles: not dissected.

Stigmatic plates: first stigmatic plate well-rounded ( Fig. 19A ). Laterotergites: laterotergite 1 slightly projecting into a sharp but short tip. Laterotergite 2 with a broad, stout, much shorter projection. Collum: with few isolated setae on entire surface. Thoracic shield: surface hirsute like tergites, longer setae only in grooves. Shallow grooves beset with numerous long setae, slope towards groove with 4 or 5 posterior keels, anterior keels absent. Tergites: surface densely setose with short setae. Tips of paratergites of midbody tergites projecting posteriorly ( Fig. 6F ). Endotergum: posterior margin conspicuously tesselated. Inner section without any setae or spines. Middle area with a single row of dense elliptical, cuticular impressions, distance between impressions slightly smaller than their diameter. Apically, 2-3 dense rows of short marginal bristles, the longest just protruding up to 2/ 3 of the distance to tergal margin. Bristles not smooth, but with numerous small spicules. Anal shield: wellrounded. Surface completely covered by tiny setae. Underside with a single, very long black, locking carina, located close to last laterotergite. Legs: leg-pair 1 with 2 ventral spines, leg-pair 2 with 4, leg-pair 3 with 6. First two leg-pairs without an apical spine. Leg-pairs 4–21 with 7–10 ventral spines and one dorso-apical spine. In leg 9, femur 1.7 times, tarsus 4.6 times longer than wide ( Fig. 19B ). All podomeres densely setose. Coxa with a large and well-rounded process. Coxal process absent at leg 1 and 2 ( Figs 19A, C ).

Female unknown

Male sexual characters: gonopore covered with a single, undivided, circular, sclerotized plate ( Fig. 19C ). Anterior telopods ( Figs 19 D–F): consisting of 4 telopoditomeres above syncoxite. Telopoditomere 1 rectangular, as long as wide. Telopoditomere 2 large, as long as telopoditomere 1. Process of telopoditomere 2 located posteriorly, visible in anterior view. Process of telopoditomere 2 wide, projecting to half of telopoditomere 4, apically with a well-rounded tip. Telopoditomere 3 cylindrical, straight, apically slightly tapering, as long as telopoditomere 4. telopoditomere 4 cylindrical, apex slightly bent posteriorly. Posterior side with a black sclerotized spot and two small, triangular spines. Telopoditomeres 1–4 with only few, mainly marginal long setae. Posterior telopods ( Figs 19G, H ): telopoditomere 1 elongated, twice 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 not expanded, only slightly wider than base. Telopoditomere 3 elongated, towards immovable finger close to apex with a slight extension carrying a small spine. Telopoditomere 4 shorter and more slender than telopoditomere 3, 2.1 times longer than wide, apically weakly tapering, very slightly curved towards immovable finger, at inner margin with two small spines. Telopoditomere 1 and 2 at both sides covered by setae. Telopoditomere 3 at base at inner margin with a few setae, remaining parts of telopoditomeres 3 and 4 almost glabrous.

Derivatio nominis: peterjaegeri, noun in apposition, after the Arachnologist Peter Jäger, great collector of arthropods in Laos and other countries.

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 19. Sphaerobelum peterjaegeri 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.