Wednesday, September 9, 2015

[Paleontology • 2015] Cushingia ellenbergeri • A Camel Spider from Cretaceous Burmese Amber

Cushingia ellenbergeri 
Dunlop, Bird, Brookhart & Bechly, 2015
the first camel spider (Arachnida: Solifugae) from Cretaceous Burmese amber. SMNS Bu-161.  

The first camel spider (Arachnida, Solifugae) from the Upper Cretaceous (lowermost Cenomanian, ca. 99 Ma) Burmese amber from Myanmar is described as Cushingia ellenbergeri gen. et sp. nov. It represents one of only a handful of fossils belonging to this arachnid order, but its precise systematic affinities are difficult to resolve. It shares characters with Karschiidae, the subfamily Gylippinae among the Gylippidae and the subfamily Dinorhaxinae containing a single, monotypic genus Dinorhax Simon, 1879 in the family Melanoblossiidae; the latter genus occurring in South-East Asia today. Its general habitus is closest to Dinorhax, but differences between the fossil and this modern genus remain. On balance, the uncertain nature of some features precludes unequivocal referral to any one of the families above. We prefer to place this new genus as Solifugae incertae sedis and further discuss the wider biogeographical implications of this find. Our new fossil is also significant for coming from a presumed forest habitat, whereas most camel spiders today are associated with arid environments.

Keywords: Arachnida; Solifugae; Amber; Cenomanian; Myanmar; Biogeography

Systematic palaeontology

Order Solifugae Sundevall, 1833
Solifugae incertae sedis

Genus Cushingia gen. nov.
Type-species. Cushingia ellenbergeri sp. nov., designated herein.

Etymology. In honour of Paula Cushing (Denver Museum of Nature and Science Colorado) in recognition of her important contributions towards camel spider biology and systematics.

Diagnosis. Gracile camel spider with all leg tarsi undivided; leg I with weak claws, legs II and III with one slender distal tibial and three slender metatarsal spiniform setae. Chelicerae with a row of elongated mesal setae; fixed finger dorsally flat and with narrow ridge along outer margin, but with acute ventral bend towards distal end. Opisthosoma strongly tapering; anus subterminal.

Cushingia ellenbergeri gen. et sp. nov.
Fig. 2, Fig. 3, Fig. 4, Fig. 5 and Fig. 6.

Etymology. In honour of the holotype's original owner, Sieghard (Ziggi) Ellenberger, who kindly made this important specimen available for study.
Holotype. SMNS Bu-161.
Type-locality. Burmese amber, Hukawng Valley, Myanmar. Upper Cretaceous (lowermost Cenomanian).

Fig. 2. Cushingia ellenbergeri gen. et sp. nov., the first camel spider (Arachnida: Solifugae) from Cretaceous Burmese amber. SMNS Bu-161. A. Dorsal view.
Fig. 3. Camera lucida drawings of the specimen shown in Fig. 1 A. Dorsal view.
Abbreviations: ch, chelicera; pp, pedipalp; legs numbered from I–IV. Scale bar equals 2 mm.
Fig. 1. Map of Myanmar showing the position of the Hukawng Valley, the locality from which most of the Burmese amber originates.

Concluding remarks
Fossil camel spiders are extremely rare and Cushingia ellenbergeri gen. et sp. nov. is the first example to be formally described from the Cretaceous Burmese amber of South-East Asia. Its familial affinities cannot be unequivocally resolved, but it appears to have most characters in common with the living genus Dinorhax. This is itself a rarity, being the only living species found in South-East Asia and one of the few camel spiders not associated with an exclusively arid environment.

Jason A. Dunlop, Tharina L. Bird, Jack O. Brookhart and Günter Bechly. 2015. A Camel Spider from Cretaceous Burmese Amber. Cretaceous Research. 56; 265–273. DOI: 10.1016/j.cretres.2015.05.003