Seppo, Selden, Paul A. & Dunlop, Jason A., 2014

Selden, Paul A. & Dunlop, Jason A., 2014, The first fossil spider (Araneae: Palpimanoidea) from the Lower Jurassic (Grimmen, Germany), Zootaxa 3894 (1), pp. 161-168 : 163

Genus Seppo n. gen.

Type species. Seppo koponeni n. sp.

Diagnosis. Palpimanoid without a cheliceral foramen; enlarged, forwardly directed leg I; short leg III; curvature of femur IV.

Etymology. After Seppo Koponen, to celebrate his 70th birthday.

Remarks. The new genus is accommodated in Palpimanoidea ( Palpimanidae , Stenochilidae , Huttoniidae , Mecysmaucheniidae , Archaeidae , † Lagonomegopidae , † Spatiatoridae , †Micropalpimanidae) on account of a variety of characters which are commonly found in, but not exclusive to, this superfamily: enlarged chelicerae with peg teeth, and a lack of true teeth, along the cheliceral furrow, the presence of a distal trichobothrium on metatarsus I, paucity of large macrosetae on the legs, curved femur of leg IV, ventral anterior sclerotization and scattered bristles on the opisthosoma. Some Palpimanoidea have large chelicerae, and peg teeth are a characteristic of the superfamily (although these are also found in other spiders, e.g. Mimetidae ). A distal metatarsal trichobothrium is characteristic of mecysmaucheniids and archaeids ( Lehtinen 1980), although we cannot be sure if others were present on this podomere, A claw on the female pedipalp tarsus occurs in many spiders; in palpimanoids, for example, it is found in Eriauchenius O. Pickard-Cambridge, 1881 , Afrarchaea Forster & Platnick, 1984 and Austrarchaea Forster & Platnick, 1984 ( Wood et al. 2012 a). The lack of macrosetae on the legs is an unusual feature of some spider families. In the new genus, numerous bristles (thin macrosetae) are present. Reduced leg spination occurs throughout Palpimanoidea and only a few other families ( Wood et al. 2012a). A curved femur IV is characteristic of all living Archaeidae ( Wood et al. 2012a). Sclerotization on the opisthosoma occurs in a variety of spider families, often in the form of a dorsal scutum; however, ventral sclerotization occurs in the epigynal area in Eriauchenius and Afrarchaea , and a reduced palpal claw is present in Colopea Simon, 1893 and in several mecysmaucheniid genera ( Wood 2008; Wood et al. 2012a). Sparse bristles on the opisthosoma is also a feature of Archaeidae ( Jocqué & Dippenaar-Schoeman 2006) .

Arguing against Palpimanoidea is the possibility of patella–tibia autospasy, which is best known from Linyphiidae , Pimoidae , Filistatidae , Leptonetidae and Hersiliidae , and some genera in the Clubionidae and Philodromidae also show a tendency for the legs to separate at this joint ( Roth & Roth 1984).

The genus differs from all palpimanoid families except Huttoniidae and the extinct families in the lack of a cheliceral foramen. A bent fourth femur is found in Archaeidae , but the femora of the fossil lack the hump seen in this family ( Wood et al. 2012a). While the combination of characters suggest Palpimanoidea, there are some characters of the superfamily which cannot be seen in the fossil, e.g. cheliceral gland mound, and sclerotization around the spinnerets. Nor it is not clear to which existing family, if any, the new genus belongs.