Olios quesitio, Moradmand, 2013

Moradmand, Majid, 2013, The stone huntsman spider genus Eusparassus (Araneae: Sparassidae): systematics and zoogeography with revision of the African and Arabian species, Zootaxa 3675 (1), pp. 1-108 : 75-76

Olios quesitio comb. nov. et replacement name

Replacement name for Eusparassus concolor Caporiacco, 1939: 353 (description of subadult male) [subadult male holotype, Ethiopia: Moyale, 13 May 1973, Prof. Zavattari leg., MZUF 212, examined] (preoccupied by Olios concolor Keyserling, 1884: 682 , pl. 21, fig. 29).

Etymology. The largest Sparassidae genus in terms of species number, Olios , needs a comprehensive revision to uncover its hidden diversity and several misplacements. “Quesitio” is the Latin translation for the term “investigation”, referring to the need for taxonomic revision of Olios spp. Noun in apposition.

Remarks. The subadult male holotype was collected by Prof Edoardo Zavattari from Borana region in Southern Ethiopia. The combination of somatic characters revealed that the specimen belongs to the genus Olios based on eye arrangement, equal length and width of prosoma, absence of intermarginal denticles, presence of two to five thick bristles at retromarginal side of chelicerae basal segment and spotted legs. The new combination is a secondary homonym of Olios concolor Keyserling, 1884 (currently considered a junior synonym of O. giganteus Keyserling, 1884 ), therefore a replacement name is proposed here.

Systematics and zoogeography

With completion of this revision, 30 species of the stone huntsman spiders, genus Eusparassus are known (including C. perezi ), of which 27 species are classified into six species groups and the rest three species are listed as incertae sedis. All species groups show a continuous range of distribution, fully to partially separated from nearby groups. The intermarginal denticles of chelicerae are present in just two species groups namely walckenaeri and jaegeri (present also in some specimens of C. perezi , but in different pattern). Thus, it could be assumed that these two groups are phylogenitically closely related. Consequently, the recently discovered Eusparassus fossil (amber), E. crassipes , is probably allied to one of these groups, since its chelicerae have distinct intermarginal denticles ( Dunlop et al. 2011: figs 2e–f). The jaegeri group is endemic to Southern Africa ( Fig.71b ) which is far from the locality of E. crassipes in Northern Europe. Thus, E. crassipes is probably closely related to the walckenaeri group whose distribution range extends into the Eastern Mediterranean region ( Fig.70a ). The remaining four species groups lack any intermarginal denticles on their chelicerae. Nevertheless, the presence of intermarginal denticles could be also the result of homoplasy and gain and loss of the character might have been taken place several times during the evolution of the members. The dufouri and vestigator groups are related in terms of the presence of the dark marking ventrally on the opisthosoma and the spination of the legs femora (I–IV 424, exception E. pearsoni 323). The disjunctive distribution of the isolated member of vestigator group, E. pearsoni in India, far from its closest relatives in Eastern Africa ( Fig. 71a ) can be explained by the following hypothesis: the occurrence of this species in Indian plate is a secondary distribution of its ancestral stock from Eastern Africa. The Indian subcontinent was not totally isolated from Africa after its separation from Gondwanaland. India was reattached to northeast Africa via Greater Somalia around 65–60 MYA (million years ago), on its northward drift toward Eurasia ( Briggs 2003). The hypothesized ancestor of E. pearsoni may have dispersed from Eastern Africa to Western India at that time. A similar scenariao was proposed for the distribution of the genus Mallinella Strand, 1906 (Zodariidae) by Dankittipakul et al. (2012). The doriae group - distributed in the Middle East to parts of Central and South Asia - might have evolved from the walckenaeri group by losing their intermarginal denticles. The tuckeri group represents an endemic lineage in Southwest Africa ( Fig.71b ). Since most parts of the distribution range of Eusparassus species are not explored yet, more species are to be expected, especially in the transition zones between different species groups.

The stone huntsman spiders inhabit semidry and dry deserts. Tectonic drifts have caused major changes in the position of the continents and consequently those of deserts. Many of the current deserts are geologically young, but in contrast, the world’s oldest desert is believed to be the Namib Desert, originating from some 55 MYA ( Ward 2009). Since the close relatives of Eusparassus and Eusparassinae (e.g. Pseudomicrommata , Arandisa , Leucorchestris and Carparachne ) are living in the Namib Desert and nearby regions, this area is a potential centre of origin of Eusparassus spp. This hypothesis of a Southern African origin of Eusparassus is supported by the absence of representatives in the Americas, Madagascar and Australia (previous records from these regions proved to be misidentifications). Thus, Eusparassus does not have a Gondwanan distribution and probably evolved after the breakup of the supercontinent Gondwanaland, which was completed in Early Cretaceous at around 110–100 MYA ( Briggs 1995). Diversification of the genus and area expansion probably occurred during the Tertiary.

Figures

FIGURE 70. Distribution range of (a) Eusparassus walckenaeri group; (b) Eusparassus dufouri group.

FIGURE 71. Distribution range of (a) Eusparassus vestigator group; (b) Eusparassus tuckeri and jaegeri groups.