Material. Holotype PA 340 (female), allotype PA 2388 (male), other specimens attributable to this species: PA 1931, PA 2384 6/7, and PA 2502 (sex unknown), all mounted in Canada Balsam, deposited in the ‘Laboratoire de paléontologie’, ‘Muséum national d’histoire naturelle’, Paris.

Etymology. After our colleague Prof. Jean-Jacques Menier, Entomology Department, MNHN, Paris.

Type strata. Lowermost Eocene, in amber, circa –53 Myr, Sparnacian, level MP7 of the mammal fauna of Dormaal [17].

Type locality. Farm Le Quesnoy, Chevrière, region of Creil, Oise department (northern France).

Diagnosis. That of the genus.

Description. Body with hairs short and relatively sparse, all simple and unbranched. Head 0.80 mm long, 0.80 mm wide, 1.0 mm high, without mandibles; 12 antennal segments in both male and female; no visible papillae or setae on antennal segments; antennal socket contiguous with frontoclypeal suture; no subantennal sclerite; apical margin of last antennal segment rounded apically, not truncate; clypeus rounded rather than truncate, not divided into three parts by longitudinal lines, clypeus of male without brush; mandible entire externoventrally but with a notch on its externoventral margin; hypostoma not closing the mandibular socket; lateral ocellus normal, rounded; eye with inner orbit strongly emarginate.

Mesosoma 1.80 mm long, 0.9 mm wide; pronotal collar rounded in lateral view; mesopleuron without epicnemial carina; episternal sulcus reaching the ventral area of mesopleuron, not curving forward and then downward parallel to the front margin of mesopleuron; mesopleuron without coarse horizontal ridges; notauli present but short, not extending over three fourths of the scutal length; mesoscutum without oblique scutal carina; propodeum not distinctly toothed; propodeal dorsum finely chagrinate; apophyseal pit in posterior third of metasternum; metasternum with a median longitudinal carina; metasternum anteriorly as wide as posteriorly.

Profemur 0.64 mm long, 0.28 mm wide; tibia 0.4 mm long, 0.14 mm wide; tarsus 0.74 mm long; fore tarsal rake rudimentary, formed of very short dorsal setae, organised in four groups of a single and a pair of setae on tarsomere 1, and one pair of setae on other tarsomeres; mesofemur 0.70 mm long, 0.30 mm wide; tibia triangular, 0.74 mm long, 0.30 mm wide; tarsus 1.14 mm long; midcoxae not contiguous; metafemur 0.80 mm long, 0.36 mm wide; tibia 0.76 mm long, 0.26 mm wide; tarsus 1.20 mm long; meso- and metatibial spurs flattened with margins serrate; hindcoxa with an inner and an outer dorsal carinae; tibial spur formula 1-1-2; hind femur simple apically, only bearing a very small process on its inner and outer faces; hind leg with tarsomere 1 as wide as following tarsomeres, 0.60 mm long, length of following tarsomeres 0.60 mm; tarsal claws simple.

Forewing 2.80 mm long, 0.72 mm wide; stigma much smaller than first submarginal cell; prestigmal length of first submarginal cell distinctly shorter than half cell length; forewing with three submarginal cells; second submarginal cell not petiolated, 0.26 mm long, third submarginal cell 0.24 mm long; vein 1m-cu not ending in second submarginal cell but in its postero-basal angle; marginal cell of forewing 0.78 mm long, 0.20 mm wide, acute distally, with apex extending well beyond outer veinlet of submarginal cell 3.

Hind wing poorly visible, circa 1.80 mm long; vein M diverging from M + Cu before vein cu-a; hamuli divided into two groups; jugal lobe small, at least in PA 1931.

Metasoma 2.50 mm long, 0.90 mm wide, sessile; first metasomal segment broader than long; no oblique groove on sterna 3 and 4; female pygidial plate very reduced or absent; male genitalia not visible, but sternum VIII elongate, narrow, and simple.

Discussion. After Brothers and Carpenter [9], Eopison gen. n. falls in the clade ‘sphecids + apids’ (= Sphecidae sensu stricto + Apoidea) and is excluded from the Heterogynaidae because of its meso- and metatibial spurs flattened with margins serrate, and mesotibia with only one spur (two in Heterogynaidae), among other characters.

Following the key to ‘Apiformes’ and Spheciformes’ of Finnamore and Michener [13], Eopison gen. n. falls into the Spheciformes (sphecid wasps) because of its body setae all simple, unbranched, and hind leg with tarsomere 1 as wide as following tarsomeres. Within this group, it would fall in the ‘Philanthidae’: ‘Philantinae’ (= Philanthinae: Philanthini sensu Bohart and Menke [8]) because of the following characters: female fully winged; forewing with closed cells; mesotibia with one apical spur; tarsal claws simple; metasoma sessile; forewing with stigma much smaller than first submarginal cell; prestigmal length of first submarginal cell distinctly shorter than half cell length; mesoscutum without oblique scutal carina; pronotal collar rounded in lateral view; clypeus not divided into three parts by longitudinal lines; lateral ocellus normal, rounded; mesopleuron without epicnemial carina; mesopleuron with an episternal groove extending to ventral region; hind wing with vein M diverging from M + Cu before vein cu-a; mandible entire externoventrally; metafemur simple, not modified apically; eye with inner orbit emarginate.

Following the key to sphecid subfamilies of Bohart and Menke [8], Eopison gen. n. would also fall in the Philanthinae or ‘Larrinae’ sensu Bohart and Menke [8] (= Craboninae sensu Ohl [18]) because of the following characters: metasoma sessile; mid tibia with only one apical spur; episternal sulcus not curving forward and then downward parallel to front margin of mesopleuron; notauli present but short, not extending over three-fourths of scutal length; midcoxae not contiguous; clypeus not divided into three parts; hind femur not truncate at apex; hind ocellus normal; no oblique scutal carina; propodeum not distinctly toothed; fore wing with three submarginal cells.

Following Bohart and Menke [8] and Alexander [2], within the Recent sphecid wasps, only the Philanthini and the crabonine tribe Trypoxylini have the inner margin of compound eyes notched or emarginated. The fossil Burmastatinae Antropov, 2000 differ from Eopison gen. n. in its inner-eye orbit straight and their midtibia with two apical spurs, and the fossil Cirrosphecinae Antropov, 2000 differ from Eopison gen. n. in the forewing venation and dentate tarsal claw [5].

Alexander [2] indicated that there are few unambiguous synapomorphies of the Philanthinae. Those of the larva are unavailable in our specimens. The other putative synapomorphy of the Philanthinae is the presence of a male clypeal brush. The male specimen PA 2388 of Eopison lacks any clypeal brush. Furthermore, Eopison gen. n. differs from the Philanthinae in its antennal socket contiguous with frontoclypeal suture and in its hypostoma not closing the mandibular socket. The closed mandibular socket and the antennal sockets remote from the clypeus are synapomorphies of the Philanthinae but are also present in some other Sphecidae, after Alexander [2] and [3]. Alexander [1] and [3] also considered the closed mandibular socket, and the presence of a delimited subantennal sclerite, both absent in Eopison gen. n., as synapomorphies of the (Philanthini + (Cercerini + Aphilanthopini)). Therefore, Eopison gen. n. cannot be attributed to the Philanthinae.

Eopison gen. n. also differs from Philanthus Fabricius, 1790 and Trachypus Klug, 1810 in its forewing vein 1m-cu not ending in the second submarginal, cell but in its postero-basal angle. Thus, its discoidal cell is shorter than those of these genera. The apophyseal pit of Eopison gen. n. is in posterior third of its metasternum, and its metasternum has a median longitudinal carina as in the group ((Trachypus + Philanthus) + Philanthinus). But the metasternum of Eopison gen. n. is anteriorly as wide as posteriorly, unlike in this group.

The hind wing jugal lobe is small in Trypoxylini. This structure is not visible in the holotype and allotype of Eopison, but the third specimen PA 1931, attributable to this taxon, has a small jugal lobe. The Craboninae have their hindcoxa dorsally carinate as in Eopison gen. n. This last character is considered as a synapomorphy by Lomholdt [14 (p. 21)]. This would support the attribution of Eopison gen. n. to the Craboninae: Trypoxylini, but Menke [15 (p. 17)] indicated that a hindcoxal carina is not unique to the Craboninae and not universally present in this subfamily. Also, Alexander [3 (p. 36)] proposed to characterize the Philanthinae by the synapomorphic absence of this carina, thus the polarisation of this character remains somewhat uncertain.

Lomholdt [14] proposed a phylogenetic analysis of the ‘Larrinae’. Eopison gen. n. falls into the Trypoxylini because of the following synapomorphies: pygidial plate lost or reduced; intercoxal carina present; eyes emarginate; hind wing hamuli divided into two groups. The same author considered the second submarginal cell petiolated as the synapomorphy that supports a very large clade that comprises the ‘Craboniformia’, the Miscophini sensu stricto, the Trypoxylini and two other genera. This would contradict the attribution of Eopison gen. n. to this clade, but the structures and sizes of the submarginal cells are very diverse in the Sphecidae, suggesting that this character is homoplastic. Therefore, we attribute Eopison gen. n. to the Trypoxylini.

After Bohart and Menke [8], Eopison gen. n. is more similar to Pison Jurine, 1808 than to other Recent trypoxyline genera because of the following characters: three submarginal cells in fore wing; antennal socket contiguous with frontoclypeal suture; metasoma compact and sessile; mesopleuron without coarse horizontal ridges; marginal cell of forewing acute distally, with apex extending well beyond outer veinlet of submarginal cell 3; no oblique groove on sterna 3 and 4; no defined pygidial plate in female.

After Bohart and Menke [8 (p. 334)] and Menke [15], Eopison gen. n. shares with the Neotropical subgenus Entomopison Menke, 1968 (synonymised with Pison by Menke [15]), and with some Pison species from New Guinea and Australasia the presence of a notched externoventral margin of mandible.

In Recent Trypoxylini and especially in Recent Pison species, when three submarginal cells are present, the second is petiolated, unlike in Eopison gen. n. [8 (pp. 327–328)]. The reduction in the number of submarginal cells in Sphecidae occurs several ways, i.e. loss of the outer veinlet (1r-m) of second submarginal cell, loss of the inner veinlet (1r), loss of third submarginal cell. Therefore, it is admissible that a fossil genus of the lineage of Trypoxylini and maybe of Pison could have three well-developed submarginal cells.

Eight fossil Sphecidae are currently attributed to the Trypoxylini: four Trypoxylon, viz. T. dominicanum Prentice and Poinar, 1993, T. eucharis Prentice and Poinar, 1993, T. pallidiventre Prentice and Poinar, 1993, and T. electrum Antropov, 1995 (Oligocene/Miocene Dominican amber) that have long petiolated metasoma and one or two submarginal cells, and four Pison, viz. P. antiquum Antropov and Pulawski, 1996 (Oligocene/Miocene Dominican amber), P. electrum Antropov and Pulawski, 1989 (Late Eocene Baltic amber), P. cockerellae Rohwer, 1908 (Early Oligocene of Florissant, Colorado, USA), and P. oligocenum Cockerell, 1908 (Late Eocene Baltic amber). They all differ from Eopison gen. n. in their very small second submarginal cell of forewing [4], [6], [10], [11], [19] and [21]. P. antiquum has no notch on posterior margin of mandible, unlike Eopison gen. n. and P. electrum [6], [7] and [15].

Pison eocenicum sp. n. (Fig. 2)

Material. Holotype PA 12238 1/4 (female). Paratypes PA 1129 (sex unknown, with two Coleoptera and a Diptera), PA 2360 1/4 (female, with three Mantodea), PA 2370 (female), PA 2527 (female?), PA 2363 (female), PA 2470 (female), mounted in Canada Balsam, deposited in the ‘Laboratoire de paléontologie’, ‘Muséum national d’histoire naturelle, Paris, France.

Etymology. After the Eocene age of the fossils.

Type strata. Lowermost Eocene, in amber, circa - 53 Myr, Sparnacian, level MP7 of the mammal fauna of Dormaal.

Type locality. Farm Le Quesnoy, Chevrière, region of Creil, Oise department (northern France).

Diagnosis. Forewing second submarginal cell clearly smaller than others and petiolated; vein 1m-cu ending in first submarginal cell, well basal of second submarginal cell; an imaginary line between the apex of marginal cell and the distal hindcorner of the second discoidal cell not crossing third submarginal cell; second submarginal cell distinctly higher than its petiole; petiole distinctly shorter than anterior margin of third submarginal cell; forewing M diverging distal of cross-vein cu-a; mandibles not notched; mesopleuron with fine horizontal ridges; propodeal dorsum with strong reticulation; scutum finely chagrinate.

Description. Body with hairs short and relatively sparse, all simple and unbranched.

Head circa 1 mm long, 1.28 mm wide; 12 antennal segments; no visible papillae or setae on antennal segments; antennal socket contiguous with frontoclypeal suture; no subantennal sclerite; apical margin of female last antennal segment rounded apically, not truncate; clypeus rounded, not divided into three parts by longitudinal lines; mandible entire externoventrally, and without a notch on its externoventral margin; hypostoma not closing the mandibular socket; lateral ocellus normal, rounded; eye with inner orbit emarginate.

Mesosoma 1.80 mm long, 1.0 mm wide; pronotal collar rounded in lateral view; mesopleuron without epicnemial carina; episternal sulcus reaching ventral area of mesopleuron, not curving forward and then downward parallel to front margin of mesopleuron; mesopleuron without coarse horizontal ridges but with fine horizontal ridges; notauli present but short, not extending over three-fourths of scutal length; scutum finely chagrinate; mesoscutum without oblique scutal carina; propodeum not distinctly toothed; propodeal dorsum with very strong reticulation; apophyseal pit in posterior third of metasternum; metasternum with a median longitudinal carina; metasternum anteriorly as wide as posteriorly.

Profemur 0.56 mm long, 0.24 mm wide; tibia 0.66 mm long, 0.24 mm wide; tarsus 0.66 mm long; fore tarsal rake rudimentary; mesofemur 0.66 mm long, 0.28 mm wide; tibia 0.64 mm long, 0.24 mm wide; tarsus 0.86 mm long; midcoxae not contiguous; metafemur 0.76 mm long, 0.20 mm wide; tibia 0.82 mm long, 0.20 mm wide; tarsus 1.10 mm long; meso- and metatibial spurs flattened with margins serrate; hindcoxa with an inner and an outer dorsal carinae; tibial spur formula 1–1-2; hind femur simple apically, only bearing a very small process on its inner and outer faces; hind leg with tarsomere 1 as wide as following tarsomeres, 0.60 mm long, length of following tarsomeres 0.50 mm; tarsal claws simple.

Forewing 2.60 mm long, 0.80 mm wide; stigma much smaller than first submarginal cell; prestigmal length of first submarginal cell distinctly shorter than half cell length; forewing with three submarginal cells; second submarginal cell petiolated, 0.15 mm long, 0.10 mm wide, with petiole 0.02 mm long; third submarginal cell 0.12 mm long, with anterior side 0.10 mm long; vein 1m-cu ending in first submarginal cell, 0.16 mm basal of its postero-basal angle of second submarginal cell; marginal cell of forewing 0.68 mm long, 0.20 mm wide, acute distally, with apex extending well beyond outer veinlet of submarginal cell 3; an imaginary line between apex of marginal cell and distal hindcorner of second discoidal cell not crossing third submarginal cell; M-diverging 0.04 mm distal of cross-vein cu-a.

Hind wing 1.72 mm long, 0.44 mm wide; vein M diverging from M + Cu 0.04 mm before vein cu-a; hind wing hamuli divided into two groups.

Metasoma circa 2.0 mm long, 0.96 mm wide, sessile; first metasomal segment broader than long; no oblique groove on sterna 3 and 4; female pygidial plate very reduced or absent.

Discussion. Pison eocenicum sp. n. can be attributed to the Sphecidae: Philanthinae or ‘Larrinae’ for the same reasons as above. Its inner margin of compound eyes is clearly notched. Thus, it could fall in Philanthini or Trypoxylini. The Philanthini are excluded because its antennal socket are contiguous with frontoclypeal suture and in its hypostoma is not closing the mandibular socket. It falls in the Trypoxylini because of the following synapomorphies: pygidial plate lost or reduced; intercoxal carina present; eyes emarginate; hind wing hamuli divided into two groups (clearly visible in PA 2340). P. eocenicum sp. n. is more similar to Pison than to other Recent trypoxyline genera because of the following characters: three submarginal cells in forewing; antennal socket contiguous with frontoclypeal suture; metasoma compact and sessile; mesopleuron without coarse horizontal ridges; marginal cell of forewing acute distally, with apex extending well beyond outer veinlet of submarginal cell 3; no oblique groove on sterna 3 and 4; no defined pygidial plate in female.

P. eocenicum sp. n. differs from Eopison gen. n. as follows: in forewing, second submarginal cell clearly smaller than others and petiolated; vein 1m-cu ending in the first submarginal cell, far from the second one; mandibles not notched; mesopleuron with fine horizontal ridges; propodeal dorsum with strong reticulation, instead of being finely chagrinate.

P. eocenicum sp. n. differs from P. electrum in its mandibles not notched and its vein 1m-cu ending well basal of second submarginal cell; an imaginary line between apex of marginal cell and distal hindcorner of the second discoidal cell not crossing the third submarginal cell; propodeal dorsum with very strong reticulation, instead of having sparse ridges. P. eocenicum sp. n. differs from P. antiquum in its second submarginal cell distinctly higher than its petiole; petiole distinctly shorter than the anterior margin of the third submarginal cell; vein 1m-cu ending more basal of second submarginal cell than in P. antiquum. P. eocenicum sp. n. differs from P. cockerellae in its scutum finely chagrinate instead of having coarse, dense punctures; propodeal dorsum with very strong reticulation, instead of having oblique ridges extending from the median carina; an imaginary line between apex of marginal cell and distal hindcorner of second discoidal cell not crossing the third submarginal cell. P. eocenicum sp. n. differs from P. oligocenum in its forewing M diverging distal of cross-vein cu-a, instead of slightly proximal; and its vein 1m-cu ending well basal of second submarginal cell.

These two Early Eocene Trypoxylini are morphologically very similar and closely related to the Recent representatives of this group of spider-hunting wasps. Together with the great abundance and diversity of spiders in the same amber, they support the great antiquity of this parasitism relation that probably originates during the Late Mesozoic. It is a further evidence of the antiquity and stability of the Recent families and subgroups of insects [16]. It also questions the exact impact on the insects and other terrestrial arthropods of the alleged mass extinction at the Cretaceous–Cainozoic boundary.