The millipede genus Globanus Attems, 1914, endemic to São Tomé and Príncipe, with the description of a new species (Diplopoda, Spirostreptida, Spirostreptidae)

Abstract During a soil zoological expedition to São Tomé and Príncipe in 2010 by the California Academy of Sciences, millipedes of the genus Globanus were collected. Samples of G.marginescaber (Karsch, 1884) and G.integer (Karsch, 1884) were recovered in addition to those containing a new species. Globanusdrewesisp. nov. is described and additional records, illustrations, and descriptive notes are given for the other two species. A key to all three species of the genus is provided, and a distribution map is presented. The monotypic genus Lobogonus Demange, 1971, which includes L.trilobatus Demange, 1971, from Sierra Leone, mainland western Africa, is revalidated and removed from synonymy under Globanus. Lobogonus is illustrated from a type specimen.


Introduction
São Tomé and Príncipe are two volcanic islands in the Gulf of Guinea straddling the Equator ca 250 km west off the coast of Gabon. Together with Annobon and Bioko, they belong to the Cameroon volcanic chain. These are classical oceanic islands long known for their peculiar biota. Although the bird fauna is relatively well documented (Christy and Clarke 1998) and a flora exists since the 1920s (Liberato andEspirito Santo 1972-1982) that describes the major elements of the islands' botany, many other important animal groups remain badly understudied, with Diplopoda, or millipedes, being one of them.
The genus Globanus had been considered endemic to São Tomé and Príncipe until Krabbe (1982), in her global revision of Spirostreptidae, synonymized Globanus with Lobogonus Demange, 1971, and thus extended the distribution of Globanus to mainland western Africa. She only recognized two valid species, G. integer and G. trilobatus (Demange, 1971). The latter species is from Sierra Leone, even though Brolemann (1935), albeit cryptically inside an introductory part to his Faune de France monograph, had beautifully depicted the gonopod of Aulonopyge marginescaber (= Globanus marginescaber).
In 2010, R.C. Drewes (California Academy of Sciences) collected millipedes in addition to his herpetology speciality for six weeks on São Tomé and Príncipe, but the samples consist of only one order, family, and genus: Spirostreptida, Spirostreptidae, Globanus Attems, 1914. Globanus integer (Karsch, 1884) and G. marginescaber (Karsch, 1884 were both recovered on each island, along with one new species. This suggests that a Globanus "species swarm" exists on both São Tomé and Príncipe islands.
The present paper is a review of Globanus, with the description of a new species endemic to São Tomé Island. The Sierra Leone genus Lobogonus is revalidated and removed from synonymy under Globanus.

Material and methods
This study is based on material collected in 2010 by R.C. Drewes. Some additional samples were obtained from the Muséum national d'Histoire naturelle (MNHN), Paris, France and the Royal Museum for Central Africa (MRAC), Tervuren, Belgium.
All samples are stored in 70% ethanol. Photographs were made with a Leica DFC 500 digital camera mounted on a Leica MZ16A stereo microscope. Images were processed with a Leica Application Suite program. Specimens for scanning electron microscopy (SEM) were air-dried, mounted on aluminium stubs, coated with gold and studied using a JEOL JSM-6480LV scanning electron microscope.

Remarks.
Having studied the original description, closely examined the type species of the genus Lobogonus Demange, 1971 (Mt Loma region, Sierra Leone, MNHN, types), and compared its gonopods to those of Globanus spp., we disagree with the decision of Krabbe (1982) to merge Lobogonus with Globanus. Krabbe synonymized these two genera on account of similarities in gonopod structure, but the similarities appear to be rather superficial. In addition, both of the genera show different, totally disjunct distributions; Globanus is confined to São Tomé and Príncipe, whereas Lobogonus occurs in the Mont Loma region, Sierra Leone. Lobogonus trilobatus is a large millipede (ca 200 mm long) with long legs (80% of maximum body diameter; Fig.  1A, B), vs. Globanus species, which are considerably smaller and show relatively short legs (ca 60% of maximum body diameter; Fig. 2A, E). Lobogonus trilobatus has a pilose gnathochilarium, in contrast to the poorly setose one observed in Globanus species (Fig. 2D). Similarities of the gonopods are also superficial and only concern the posttorsal process of the gonotelopodites, with 2 or 3 lobes or processes observed in both genera. In Globanus these lobes are subapical lobes, whereas in Lobogonus they are apical. The gonocoxite of L. trilobatus is rather stout and large ( Fig. 1C-E) compared to the slender gonocoxite observed in Globanus species.
Diagnosis (after Krabbe 1982, with modifications). A genus of moderate-sized millipedes (up to 65 mm long with relatively short legs (ca 60% of maximum body diameter)). Gnathochilarium notable in that the surface sculpture of the mentum shows a submedian transverse groove (Fig. 2D, sg). Gonopod metaplica extended into an apicolateral projection, proplica slender, with or without a distolateral spine. Telopodite with a long, slender, antetorsal process, with a post-torsal process situated more distally, with 2 or 3 lobes proximal to an attenuating and slender tip.   Etymology. Honours Bob Drewes, the collector. Diagnosis. Distinguished from other species of the genus by the acuminate distal prolongation of the gonopod proplica. Post-torsal process of telopodite with two attached lamellae; apex rotated 360°ending in a tongue-shaped process.
Description. Holotype, adult male with 52 body rings (including preanal ring), length ca 65 mm (curved and broken), maximum body diameter 4.23 mm.
First pair of male Iegs as shown in Fig. 2F, with 5 or 6 setose tubercles laterally; each prefemur with a prominent basal projection on anterior side and with short setae medially. Second pair of legs and penes as in Figure 2E. Walking legs rather short (length 61% of midbody diameter, only tarsi visible from above when stretched; Fig.  2E, H), distal third with ventral tibial pads extending to proximal third of tarsi. Tarsal claws long and curved, each with a small basal seta (Fig. 2I, s).
Gonopods with a small sternum; proplica (pp) slender, with an acuminate distolateral spine and a field of short setae proximal to it. Metaplica (mp) slender proximally, expanded distally to form a latero-apical metaplical process (lap), slightly projecting outside the body when at rest (Fig. 3A-C). Telopodite as shown in Figure 3D, E, placed on anterior side of gonopod, antetorsal process (atp) long and slender, originating near arculus. Torsate region comprising less than half of telopodite length, distal third giving rise to a flattened blade (fb) and, beyond this, to a subtriangular projection (sp) (Fig. 3D). Apex rotated 360° ending in a tongue-shaped process. Prostatic groove running straight to tip of solenomere, ending just before the tongue-shape process level to a small digit (Fig. 3F).
Paratype male agrees with holotype in all structural details, but females larger (up to 80 mm in length and ca 6 mm in diameter), with short legs (ca 60% of midbody diameter) devoid of tibial pads; the number of body rings also varies between specimens (up to 56 body rings including preanal ring). Vulvae placed vertically inside segment 3; no setae on vulvae.
The other characters agree with those of the holotype. Distribution. The species seems to be endemic to São Tomé Island. Relationships. Although the three species of Globanus are externaly very similar, the gonopod structure suggests that the new species is closer to G. marginescaber. In both species, the median lamella of the telocoxite shows a well-marked distal proplica spine, which is absent in G. integer. Figure 4 Spirostreptus ( Diagnosis. Differs from G. integer by the presence of a distal proplica spine and from G. drewesi by the absence of a subtriangular projection in the distal third of the telopodite.

Globanus marginescaber (Karsch, 1884)
Description (based on specimens CAS 9032625). Length of males ca 55 mm, width of midbody metazonae ca 0.5 mm, length of females ca 55 mm, width of midbody ca 5 mm. Colour in alcohol brown, prozonae usually light brown; antennae and clypeolabral region light yellow-brown; venter and legs yellowish.
Somatic characters as in previous species (Fig. 4A).
Gonopods with a small sternum; proplica slender, with an acuminate distolateral spine and a field of short setae proximal to it. Metaplica slender proximally, expanded distally to form a lateral cone, slightly projecting outside body when at rest (Fig. 4B). Telopodite as shown in Figure 4D, placed on anterior side of gonopod; antetorsal process long and slender, originating near arculus. Torsate region comprising approximately half of telopodite length, proximal third giving rise to an acute lateral process; beyond this, telopodite slightly flattened and attenuating regularly towards tip (Fig. 4C). Prostatic groove running straight to tip of solenomere, ending just before telopodite apex. Remarks. This species was originally described so poorly by Karsh (1884) from the female holotype that Attems (1914) considered it as a species incertae sedis. The holotype is still in the Berlin Museum (ZMB), but its revision reveals that actually it belongs to the family Harpagophoridae and is definitely not the true type of marginescaber. This was already observed by Richard Hoffman (pers. comm.), who suggested some mixing of labels, which must have occurred when the collection was re-organized. The first illustration of the gonopods was published in a text book by Brolemann (1935: 63), simply to show the complex conformation of a spirostreptid gonopod. Krabbe (1982), in her revision of the family Spirostreptidae, did not mention the species, but Spelda (1993) did and provided new drawings of the gonopods of both Globanus species then known from São Tomé and Príncipe. The gonopod structure of the specimen observed here agrees with the drawing presented by Spelda (1993) for G. marginescaber, except that our male shows no small spine beyond the lateral process. Another difference is the body size; the samples from the MNHN are much larger compared to the specimens collected by R.C. Drewes: males to only 11 cm long (maximum body diameter 0.9 cm) and females to 13.5 cm long (maximum body diameter 1 cm).
This species occurs both on São Tomé and Príncipe. Figure 5 Spirostreptus ( Diagnosis. Differs from congeners by the absence of a distal proplica spine, telopodite distally stout and with attached, large, plate-like lamellae. Remark. The gonopod structure of a topotype (Fig. 5) agrees closely with the drawings presented by Spelda (1993).

Conclusion
Globanus trilobatus, originally described in the monotypic Lobogonus (Demange 1971) and then relegated to Globanus by Krabbe (1982), is returned to Lobogonus with that genus revalidated. A close examination of type specimens of L. trilobatus (in the MNHN) shows that species of these two genera are strikingly different both in habitus and gonopod structure and also have completely disjunct distributions. Thus, there is clear support for the separation of Globanus and Lobogonus. The oligotypic genus Globanus currently encompasses three species and seems to be endemic to São Tomé and Príncipe islands. Among the species, only G. marginescaber occurs on both islands, while G. integer and G. drewesi sp. nov. apparenty are restricted to the larger São Tomé Island (Fig. 6). The trio may well be regarded as another example of "insular species swarms" among Diplopoda, however small, much like several others long reported from all main archipelagos of Macaronesia, as well as the Hawaiian Islands and New Caledonia (e.g. Enghoff 1992Enghoff , 1993.