Sphaerobelum pumatense, Semenyuk & Golovatch & Wesener, 2020

Semenyuk, Irina, Golovatch, Sergei I. & Wesener, Thomas, 2020, Some new or poorly-known Zephroniidae (Diplopoda, Sphaerotheriida) from Vietnam, ZooKeys 930, pp. 37-60 : 37

Sphaerobelum pumatense sp. nov. Figs 1A-C , 3B , 6

Material examined.

Holotype ♂ (ZMUM Rd 4647), Vietnam, Nghe An Prov., Pu Mat National Park, 18°56'N, 104°38'E, 200 m a.s.l., mixed tropical forest on steep slopes, on forest floor, daytime, IV.2018, I.I. Semenyuk leg. Paratypes 1 ♂, 1 ♀ (ZMUM Rd 4632), 1 ♂, 2 ♀ (ZMUM Rd 4648), 1 ♂, 1 ♀ (ZFMK MYR8942), same data as holotype.

Diagnosis.

Sphaerobelum pumatense sp. nov. belongs to the group of congeners in which the mesal margin of the femur is extended into several teeth (Fig. 6F ). In addition, S. pumatense sp. nov. shares only with S. spinatum Wesener, 2019 and S. nigrum Wesener, 2019, both from Laos, and with S. cattiense Semenyuk et al., 2018 and S. konkakinhense Semenyuk et al., 2018, both from Vietnam, a straight telopoditomere 4 of the posterior telopod (Fig. 6A, B ). Sphaerobelum pumatense sp. nov. differs in several unique characters from the four other species: vulval operculum not projecting mesally into a strong tip (Fig. 6H ); telopoditomere 4 of posterior telopods exceptionally slender,>5 × as long as wide (Fig. 6A, B ).

Description.

Body length: holotype ♂ length ca. 27.2 mm, width of thoracic shield 15.61 mm, of tergite 7 (= broadest), 15.5 mm, height of thoracic shield, 7.9 mm, of tergite 7 (= highest), 8.2 mm; ♀ length ca. 34.8 mm, width of thoracic shield, 17.2 mm, of tergite 7, 17.9 mm (= broadest), height of thoracic shield, 9.5 mm, of tergite 7, 9.9 mm (= highest). Width of paratypes 14-17 (♂) or 15-17 mm (♀). Coloration: both in vivo and in vitro, after>1.5 years of preservation in ethanol, similar, uniformly dark blackish brown, dark chestnut, dark grey-brown or dark reddish brown, in alcohol with posterior margin usually dark brown, paratergite depressions, groove of thoracic shield and legs dark olive to olive-brown, but several basal podomeres and distal halves of tarsi considerably lighter, orange. Antennae blackish to dark brown, but antennomeres 5 and 6 lighter, light brown to nearly orange. Tegument mosly dull to poorly shining (Fig. 1A-C ). Head: eyes with>75 ommatidia. Aberrant ocellus located inside antennal groove. Antennae short (Fig. 6G ), with rounded joints, protruding posteriorly to leg-pair 3. Lengths of antennomeres: 1 = 2 = 3 = 4 = 5 << 6. All antennomeres densely pubescent, sensilla basiconica surrounding apical disc. Shape of antennae sexually dimorphic, cylindrical in ♀, thickened, apically broadened and flattened in ♂. Apical disc with ca. 63/67 (♂) or 48/45 (♀) apical cones, respectively. Organ of Tömösváry located inside antennal groove. Gnathochilarium: palpi with sensory cones arranged in a single field. Mandibles : not dissected. Stigmatic plates: first stigmatic plate rounded, apex well-rounded, straight towards coxa 1. Laterotergites : laterotergite 1 strongly elongated into a well-ronded tip. Laterotergite 2 with a broad, stout, much shorter projection. Collum: with few setae on surface, anterior and posterior margins with 3-4 rows of short setae. Thoracic shield: surface like tergites, longer setae only in grooves. Slope towards groove without anterior, but with 3 or 4 posterior keels. Tergites: surface densely setose with short setae standing in pits. Tips of paratergites of midbody tergites slightly 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>2 × their diameter. Apically, two sparse rows of marginal bristles, tips of longest setae slightly protruding beyond tergal margin (Fig. 3B ). Bristles not smooth, but barbed, with numerous small spinicles. Anal shield: large, in both sexes regularly rounded. Surface in both sexes completely covered with tiny setae located in small pits. Underside with a single, long, black, locking carina 2 × as long as width of last laterotergite. Carina located close to last laterotergite. Legs: leg 1 with 6, leg 2 with 7, leg 3 with 7 or 8 ventral spines. First two leg-pairs without an apical spine. Leg-pairs 4-21 with 10-12 ventral spines and one dorso-apical spine. In leg 9, femur 1.6, tarsus 4.5 times longer than wide (Fig. 6F ). All podomeres densely setose. Coxa with a large and process dentate at margins. Coxa process absent from first and sharply projecting in second leg. Prefemur at apical margin with a projection mesally. Femur extended mesally into a dentate margin featuring 12-14 teeth. Female sexual characters: vulva large, covering half of coxa, extending mesally to anterior third of prefemur (Fig. 6H ). Operculum rounded, very slightly invaginated medially, mesal margin slightly projecting into a well-rounded lobe slightly higher than remaining operculum. Subanal plate: large and wide, centrally recessed. Male sexual characters: gonopore covered with a single, undivided, circular, sclerotized plate. Anterior telopods (Fig. 6C-E ): consisting of 4 telopoditomeres distal to syncoxite. Telopoditomere 1 rectangular, as long as wide. Telopoditomere 2 large, without process, as long as telopoditomere 1. Process of telopoditomere 2 located posteriorly, visible mesally in anterior view. Process wide, well-rounded, projecting to basal part of telopoditomere 3. Telopoditomeres 3 and 4 slightly curved mesally. Telopoditomere 3 small, cylindrical, slightly shorter than telopoditomere 4, with a spine juxtaposed to process of telopoditomere 2. Telopoditomere 4 cylindrical, well-rounded, posterior side with 2-4 small spines. All telopoditomeres covered with long setae. Posterior telopods (Fig. 6A, B ): telopoditomere 1 narrow, as long as 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, clearly rounded apically, apex only slightly wider than base. Swelling only slightly expressed basally. Telopoditomere 3 rectangular, well-rounded, apically with a clearly rounded extension carrying three small spines. Telopoditomere 4 only slightly shorter and much more slender than telopoditomere 3, 5.2 × as long as wide, apically weakly tapering, straight, not curved, with 23 small spines at margin towards immovable finger close to tip. In anterior view, telopoditomeres 1-3 covered with setae, in posterior view telopoditomeres 2-4 more glabrous except for numerous setae at margins.

Etymology.

To emphasize the provenance from the Pu Mat National Park, adjective.

Remarks.

In the field, the weather was fluctuating between very dry and hot days and several rainy days, with day temperature above the leaf litter averaging 24 °C, and night temperature averaging 21 °C, not dropping below 18.5 °C. Sphaerobelum pumatense were quite rare in any weather conditions. The millipedes were found in forests ranging from 150 m to 400 m a.s.l., the forest canopy appeared to have been free of this species. Females were mostly hidden in leaf litter in small patches of litter on very steep slopes (60-70°), forming "living rooms", choosing places with water oozing from beneath shale so that the leaf litter was constantly wet. Males were found mainly on the forest floor at night. No juveniles were seen.

Figures

Figure 1. Live Sphaerobelum pumatense sp. nov. (A-C) and Sphaerobelum bicorne Attems, 1938 (D-H) in the field A-C adult, enrolled, ventral view and walking, respectively D-F adults, ventral view, and enrolled, respectively G, H juvenile, enrolled and unrolling, respectively. Pictures taken not to scale.

Figure 3. Endoterga of midbody segments, SEM micrographs. A Sphaerobelum bicorne Attems, 1938, ♂ (ZFMK) B Sphaerobelum pumatense sp. nov., ♂ holotype C Sphaeropoeus maculatus (Verhoeff, 1924), ♂ lectotype D Sphaeropoeus bidoupensis sp. nov., ♂ holotype E Sphaeropoeus honbaensis sp. nov., ♂ holotype. Scale bars: 0.2 mm.

Figure 6. Sphaerobelum pumatense sp. nov., ♂ holotype (A-G) and ♀ paratype (H). A, B Left posterior telopod, anterior and posterior views, respectively C-E left anterior telopod, anterior, lateral and posterior views, respectively F left leg 9, anterior view G left antenna H left coxa and prefemur 2 with vulva, posterior view. Scale bars: 1.0 mm, D drawn not to scale.