Sphaeropoeus bidoupensis, 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

Sphaeropoeus bidoupensis sp. nov. Figs 2A-E , 3D , 4B , 9

Material examined.

Holotype ♂ (ZMUM Rd 4646), Vietnam, Lam Dong Prov., Bidoup Nui Ba National Park, 12°10'N, 108°41'E, 1500 m a.s.l., mixed tropical forest on hills, in leaf litter, daytime, VI.2018, I.I. Semenyuk leg. Paratypes 1 ♂, 2 ♀ (ZMUM Rd 4634), 1 ♂ (ZFMK MYR8944), 1 ♀ (ZFMK MYR8859), same data as holotype.

Diagnosis.

Sphaeropoeus bidoupensis sp. nov. differs from almost all other known continental species of the genus in the anterior telopod showing a very short, almost completely reduced telopoditomere 4, a character only shared with S. honbaensis sp. nov. Sphaeropoeus bidoupensis sp. nov. differs from S. honbaensis sp. nov. in the presence of a spine in the inner area of the large telopoditomere 3 (vs. absent in S. honbaensis sp. nov.), in the endotergum, where the distances between the cuticular impressions are slightly smaller than the diameter (vs. wider than diameter in S. honbaensis sp. nov.), the ♂ anal shield being well-rounded (weakly bell-shaped in S. honbaensis sp. nov.), and in leg structure, with leg-pair 3 having an apical spine (vs. absent in S. honbaensis sp. nov.), the prefemur showing a dentate mesal margin (vs. smooth in S. honbaensis sp. nov.), and the coxa process being weakly developed and partly sharp (vs. strongly developed and well-rounded in S. honbaensis sp. nov.).

Description.

Measurements: holotype ♂ ca. 24 mm long, 11.2 mm (2nd), up to 12.3 mm (7th) wide, 7.1 mm high (2nd the highest). Paratype ♀ (ZFMK): ca. 29 mm long, 13.5 mm (2nd), up to 14.3 mm (7th) wide, 7.7 mm (2nd) up to 9.1 mm in height (7th the highest). ZMUM paratypes 10 mm (♂), 11 mm (♀) or 13 mm wide (♀). Coloration: both in vivo and in vitro, after>1.5 years of preservation in ethanol, similar; in life, adults uniformly dark brown to blackish brown, juveniles lighter and showing vague or clear variegated tergal patterns (Fig. 2C, D ), antennae in adults orange, legs in adults mostly dark or lighter olive-brown (Fig. 2B ); in alcohol, adults likewise uniformly dark brown to blackish brown, antennae orange, legs light grey-brown to olive-grey-brown with a little lighter tarsi. Tegument mostly dull to poorly shining (Fig. 2A, B ). Head: eyes with ca. 65 ocelli. Antennae short (Fig. 9H ), protruding beyond centre of head. Antennomeres 1-5 with few longer setae, 6th densely pubescent. Antennomere 6 towards disc with a single row of sensilla basiconica. Antennomere 6 swollen in ♂, cylindrical in ♀, twice as long as, but only slightly wider than, antennomeres 1-5. ♂ with 36/40, ♀ with 17/24 apical cones. Palpi of gnathochilarium located in a single field. Collum: completely covered with long setae, like the tergites. Thoracic shield: with wide and shallow grooves, 3 or 4 weak crests present at posterior corner. Tergites: surface covered with longer setae, most innervating in small pits (Fig. 4B ). Paratergite tips of midbody tergites projecting posteriorly (Fig. 2A ). Anal shield: well-rounded. In both sexes completely covered with longer setae. Locking carina long, 2 × as long as width of last laterotergite, located close to margin. Endotergum: inner section lacking any spines or setae. Middle area with a single row of large, sparse, elliptical, cuticular impressions. Distance between impressions shorter than their diameter. Apically, two rows of long marginal bristles, tips of longest setae clearly protruding beyond tergal margin (Fig. 3D ). Bristles not smooth, but with numerous small spinicles. Stigmatic plates: first well-rounded, triangular. Laterotergites : first with a slightly projecting, well-rounded process. Laterotergites 2 and following not extended, well-rounded. Legs: first with 2 or 3, second with 5 (one of them basal), third with 8 ventral and an apical spine. Leg-pairs 4-21 each with 12-14 ventral spines and a single apical spine. Coxa process visible, partly sharp (Fig. 9G ). Femur 1.5, tarsus 4.7 times longer than wide. Femur with a very long ridge (Fig. 9G ). Mesal margin of femur completely extended into 12-14 teeth, prefemur at mesal margin with 5-8 teeth (Fig. 9G ). Female sexual characters: vulva large, covering 2/3 coxa, a conspicuous operculum extending above basal half of prefemur (Fig. 9I ). Operculum massive, larger than bursa, wider than prefemur, apically rounded. Subanal plate: large and wide, triangular. Male gonopore: opening covered with a single, apically membranous plate. Anterior telopod (Fig. 9C-F ): four podomeres, first three of equal length regardless of the processes, podomere 4 rudimentary, conical. Telopoditomere 2 with a strong, curved process overreaching telopoditomere 4. Telopoditomere 3 posteriorly with a longer process juxtaposed to apex process of telopoditomere 2, clearly protruding above telopoditomere 4, as well as both process of telopoditomere 2 and a large spine in the central area. Telopoditomere 4 conical, with a single spine. Posterior telopod (Fig. 9A, B ): podomeres 3 and 4 slightly longer than process of podomere 2. Podomere 4 short, conical, with two spines, slightly curved towards immovable finger. Podomere 3 slender, 3.6 times longer than wide. Its excavate inner margin with a membranous lobe and a single spine, posterior face with ca. 10 small crenulated teeth. Immovable finger slender, apically tapering, tip curved towards movable finger. Membranous area apically with a large, bifid, membranous lobe. Podomeres 1-3 in anterior and posterior views with few setae. Podomere 4 in both aspects glabrous.

Etymology.

To emphasize the provenance from the Bidoup Nui Ba National Park, adjective.

Remarks.

This new species was very abundant in the Park area and could be found almost throughout the year. In January, juveniles lived under logs, but no adults were recorded. The daytime temperature above the leaf litter averaged 17 °C, dropping down to 14 °C (minimum 12.5 °C) at night; rains were quite abundant. In June, juveniles colonized decaying wood, leaf litter, suspended soils in Asplenium sp. ferns, and spaces under logs. Adults lived in leaf litter and the suspended soil of ferns, only occasionally and only males walking openly on the forest floor. Juveniles and some adults were often recorded hiding inside their "living chambers" (Fig. 2C, D ), just like those observed in Sphaerobelum bicorne (see above). The daytime temperature above the leaf litter averaged 20 °C, compared to 16.5 °C (minimum 14.9 °C) at night; rains were likewise quite abundant. In November, the millipedes were mainly hidden in leaf litter. The daytime temperature above the leaf litter averaged 22 °C, vs. 14.5 °C (minimum 11.2 °C) at night; rains were particularly heavy, as a typhoon came in.

Sphaeropoeus bidoupensis sp. nov. seems only to occur in forests at about 1500 m a.s.l.. This was a riparian, very wet, broadleaved forest with abundant Asplenium sp. ferns on tree trunks starting from the ground level and a thick leaf litter layer on the floor, as well as a forest with dominating Fagaceae trees mixed with several coniferous species on slopes, the leaf litter layer being thick and to a significant proportion formed by coniferous needles. The species was not located in the adjacent mossy elfin forest up to 2000 m a.s.l. with a much cooler and wet weather.

Figures

Figure 2. Live Sphaeropoeus bidoupensis sp. nov. (A-E) and Sphaeropoeus honbaensis sp. nov. (F-H) in the field A enrolled male (left) and female (right) B adult, ventral view C adult and its excrements in a " living room " in leaf litter D early instar juvenile enrolled in its " living room ", with surrounding dead leaves eaten and excrement used to shape the room E enrolled middle-sized instar juvenile F-H adult, enrolled and walking, 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 4. Tergal surface of midbody segments, SEM micrographs. A Sphaerobelum bicorne Attems, 1938, ♂ (ZFMK) B Sphaeropoeus bidoupensis sp. nov., ♂ holotype. Scale bars: 0.2 mm.

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