Mongolarachne

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Mongolarachne
Temporal range:
Ma
↓
Pair of male (left) and female (right) fossil Mongolarachne jurassica.
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Class: Arachnida
Order: Araneae
Infraorder: Araneomorphae
Family: †Mongolarachnidae
Selden, Shih & Ren, 2013
Genus: †Mongolarachne
Selden, Shih & Ren, 2013
Type species
Nephila jurassica
Selden, Shih & Ren, 2011
Species
  • †M. jurassica Selden, Shih & Ren, 2013

Mongolarachne is an

golden silk orb-weavers.[2]

Subsequently it was determined to be

Daohugou in Ningcheng County, northeastern China[2] and the Yixian Formation.[4]

A second putative species,

Mongolarachne chaoyangensis, was described in 2019,[4] but it was subsequently shown to be a forgery based on a fossil crayfish.[5]

Jorg Wunderlich placed Longissipalpus and Pedipalparaneus from the Cenomanian aged Burmese amber into Mongolarachnidae in 2015.[6]

History and classification

Mongolarachne jurassica is known only from two fossils, the

Key Lab of Insect Evolution & Environmental Changes collections housed in the Capital Normal University, located in Beijing, China. Mongolarachne jurassica was first studied by Paul Selden of the University of Kansas and the Natural History Museum along with Dong Ren and ChungKun Shih both of the Capital Normal University. Their 2011 type description of the genus and species was published online in the journal Biology Letters. The etymology of the specific epithet jurassica refers to the age of the species.[2] The genus name Mongolarachne is derived from (Inner) Mongolia, where the fossils were found, and the Latin arachne meaning "spider". The family name is a derivative of the genus name.[1]

If it had been confirmed, placement of Mongolarachne jurassica in the genus Nephila would have made it the oldest described species of the genus Nephila, extending the known fossil range of the genus back 130 million years.

Late Eocene species Nephila pennatipes from Colorado's Florissant Formation. The oldest recognized member of the family Nephilidae is the Cretaceous species Cretaraneus vilaltae of Spain. Fossils of female specimens are known only from N. pennatipes, all other fossil nephilids having been described from male specimens.[2]

The placement of M. jurassica was first questioned by Kuntner et al. in 2013, who claimed that M jurassica differs from extant members of the genus Nephila in many anatomical traits and cannot be assigned to this genus, or indeed to the family Nephilidae. According to Kuntner et al. (2013) in an academic conference presentation following the description of the species Paul Selden (the first author of the description of M. jurassica) suggested that M. jurassica might be

synapomorphy".[3] The authors considered it more likely that this species is actually a stem-orbicularian.[3]

This assessment was confirmed later in 2013 by Paul Selden, ChungKun Shih, and Dong Ren, with the description of a male M. jurassica which has notably different pedipalp morphology from that of male Nephila. The authors moved the species to the new genus Mongolarachne, which they assigned to a separate family Mongolarachnidae. The authors considered it most likely that M. jurassica is a stem-orbicularian, more distantly related to the group Araneoidea (including nephilids) than deinopids and uloborids are.[1]

Description

The holotype female is fossilized with her underside facing up. Portions of all but two of the legs are missing from the fossil. The carapace of the holotype is 9.31 by 6.83 millimetres (0.367 by 0.269 in) and the

setae called gaiters, which are also found on the other three tibia. The feature of a gaiter on the third tibia is found only in modern Nephila and, according to the original authors of description of M. jurassica, its presence along with the large size indicated the species was part of the genus.[2]

The allotopotype male has a body length of 16.54 millimetres (0.651 in) with elongated pedipalps.[1]

See also

References

  1. ^
    PMID 24317464
    .
  2. ^
    PMID 21508021
    .
  3. ^
    PMID 23811436
    .
  4. ^
    doi:10.1111/1755-6724.13780
    .
  5. S2CID 208124459
    .
  6. ^ J. Wunderlich. 2015. On the evolution and the classification of spiders, the Mesozoic spider faunas, and descriptions of new Cretaceous taxa mainly in amber from Myanmar (Burma) (Arachnida: Araneae). Mesozoic Spiders (Araneae): Ancient Spider Faunas and Spider Evolution, Beiträge zur Araneologie 9:21-408

External links

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