The first fossil spider (Araneae: Palpimanoidea) from the Lower Jurassic (Grimmen, Germany)
Author
Selden, Paul A.
Author
Dunlop, Jason A.
text
Zootaxa
2014
3894
1
161
168
journal article
10.11646/zootaxa.3894.1.13
51daf3a1-bda9-4f88-82f5-0c6f3f20db17
1175-5326
228352
0E1B32A7-396F-481E-9A12-4B84C13127C8
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.