Sphaerotherium rotundatum Brandt, 1833

Spiegel, Didier Van den, Golovatch, Sergei I. & Hamer, and Michelle L., 2002, Revision of some of the oldest species in the millipede genus Sphaerotherium Brandt, 1833 (Diplopoda, Sphaerotheriida, Sphaerotheriidae), with new synonymies, African Invertebrates 43, pp. 143-181 : 168-171

Sphaerotherium rotundatum Brandt, 1833

( Figs 6, 7 , 33a–h )

Oligaspis puncticeps Wood, 1865 . Syn. n.

Sphaerotherium viride Porat, 1872 . Synonymy confirmed.

Sphaerotherium pubescens Porat, 1872 . Synonymy confirmed.

Material studied:

Type material: S. rotundatum : ^ holotype, Caput Bonae Spei (Cape), Krebs leg. ; ZMB 61 .

S. viride : ^ holotype, Caput Bonae Spei (Cape), 1854, [det.] von Porat ; SMNH.

S. pubescens : Ò holotype (without telopods), South Africa, Caffraria 1840–45, J. A. Wahlberg ; SMNH.

Oligaspis puncticeps : Ò neotype (selected herewith), RSA, KwaZulu-Natal, Umhlali, environs of Durban , October 1960, R. F . Lawrence ; NMSA .

Other material: Numerous Ò and ^ from MRAC, SAMC and TMSA, various dates and collectors.

Description:

Total length ranging from 7–25, width from 4–12, average length 16.

Colour: Head, antennae and collum orange brown to olive green. Thoracic shield, tergites and pygidium light brown to olive green bordered with brown along posterior margin. Underside and legs olive green to light brown.

Head with a few hairs growing longer towards clypeus; gnathochilarium pilose. Both sides of labrum broadly rounded laterad, middle scarcely emarginate, with a single median tooth. Ocelli obvious, almost black. Antennae short, last segment with four apical sensory cones.

Collum smooth, bordered with one row of long setae.

Thoracic shield smooth, brim relatively large, accompanied by a row of long setae.

Tergites without median keel, surface smooth, with neither punctures nor setae.Anterior margin with hairs growing longer laterally. Endotergum highly characteristic, comprising one row of pinnate marginal bristles not reaching tergal edge, a marginal ridge without callosities but underlined by a row of circular impressions, and an intersegmental membrane with dark cones and long setae ( Figs 6, 7 , 33e ).

Pygidium smooth, without peculiarities in both sexes.

Legs highly characteristic, without lobes on coxae but apical part of tibia showing two strong spines above ( Fig. 11 ). Coxa, femur and tibia more or less fully covered with sensory organs consisting of an intraintegumental round cavity opening by a small aperture supporting a short sensitive hair ( Figs 11 , 33c ).

Male sexual characters:

Second pair of legs without coxal lobe.

Anterior telopods with a 2-segmented tarsus ( Fig. 33f ). Posterior telopods relatively slender, lateral side of tibial process with one digitiform protuberance, tarsus incompletely or indistinctly divided in its apical part, with a row of striated knobs on anterior side and a concavity with two lobes supporting small tactile spines ( Fig. 33f, g ).

Female sexual characters:

No coxal lobe. Vulvae with operculum extremely elongated distally (rod-like) and sparsely pilose ( Fig. 33d ).

Comments: S. rotundatum is a widespread species in South Africa ( Hamer 1998), so easily identifiable that the holotype has never been re-examined prior to this study. Our observations generally indicate that S. rotundatum auct . is conspecific with the holotype. However, we have noticed certain discrepancies in the structure of the endotergum of the holotype and non-type material. This mainly concerns the cuticular pattern of the marginal ridge, which can be inconspicuous in some specimens.

We also confirm the synonymy established by Silvestri (1910), as the types of viride and pubescens also prove to represent rotundatum auct .

As S. rotundatum , the type species of Sphaerotherium , appears indeed to possess only four sensory cones on antennomere 8, this is of additional nomenclatural importance. This means that Oligaspis Wood, 1865 , with Oligaspis punticeps Wood. 1865 as type-species (see next paragraph), Neobournellum Attems, 1908 (see above under Sphaerotherium compressum ) and Tetraconosoma Verhoeff, 1924, with Sphaerotherium weberii Silvestri, 1910 as type-species, are to be confirmed here as representing strict junior subjective synonyms of Sphaerotherium s. str. To avoid the introduction of a new genus-group name, e.g. the invalidly proposed Plethoconium (cf. Attems 1943; Jeekel 1970; Hoffman 1980) to replace the subgeneric name Sphaerotherium sensu auctorum , we revive Bournellum De Saussure & Zehntner, 1902 as currently the earliest available substitute name (cf. Hoffman 1980), with the type species Sphaerotherium retusum C. L. Koch, 1847 , showing ≥7 sensory cones on the last antennomere. However, a subgeneric division of Sphaerotherium based on the number of sensory cones on antennomere 8 alone is abandoned (see above under S. dorsale ).

As regards the identity of Oligaspis puncticeps Wood, 1865 a , the decision has been made to select a neotype because the holotype that was claimed to have been deposited in the collection of the Academy of Natural Sciences in Philedalphia ( Wood 1865 a) is presumably lost (Hoffman, in litt.). Based on the original description ( Wood 1865 a) and illustrations published elsewhere (Wood 1865 b), there is no doubt that the holotype represented a juvenile male possessing about 10 body segments and under-developed telopods.The only useful information contained in the description and drawings concerns the type locality indicated as Port Natal (= Durban), the generally olive-brown colour with red-brown hind margins on the posterior tergites, the laterally swollen tibia of the posterior telopods, the gently sloping pygidium, and the smooth terga.

The neotype is an adult male kept in the NMSA collection, selected from among the samples identified by R. F. Lawrence as Sphaerotherium rotundatum . The male is 15 mm long and 7 mm wide, with the colour faded light brown, and with the hind margins of the posterior four tergites red-brown. The head is smooth, with sparse hairs, which are denser and longer towards the clypeus. The latter is somewhat punctate. The tergites have a smooth appearance, and the endotergum is as in Figs 6 and 33e , but the depressions behind the marginal ridge are not as obvious as illustrated.All other characters, including the telopods, the collum, the antennae, the leg coxae and tibial spines, are as described above for rotundatum auct .

The neotype comes from Umhlali, about 30 km north of Durban, collected in October 1960 by R. F. Lawrence, thus representing a strict topotype as well .

Figures

Figs 33a–h. Sphaerotherium rotundatum (a–e, ^ holotype). a: apical part of antenna; b: lateral aspect; c: leg 9 with sensory seta; d: cyphopod; e: endotergum; f: posterior aspect of anterior telopod; g: posterior view of apical part of posterior telopod; h: anterior aspect of posterior telopods.

Figs 1–11. Some structural details in Sphaerotherium species. 1–2. Apical part of antenna in subgenus Sphaerotherium and “Bournellum” respectively. 3. Head, collum and thoracic shield of a Sphaerotherium species. 4–5. S. retusum. 4. Tergal structure. 5. Median keel. 6–7. S. rotundatum. 6. Midbody endotergum. 7. Two marginal bristles. 8. S. punctulatum, marginal bristle. 9. S. compressum, marginal bristle. 10. Coxal lobe of 9th leg in S. obtusum (arrow). 11. S. rotundatum, detail of leg 9 showing tibial spines (arrow).