Perilampus pisticus Darling

Heraty, John M. & Darling, Christopher, 2009, Fossil Eucharitidae and Perilampidae (Hymenoptera: Chalcidoidea) from Baltic Amber, Zootaxa 2306, pp. 1-16 : 8-10

Perilampus pisticus Darling n. sp.

(Figs 12–15)

Description of Male. Length approximately 2 mm. Body color, including antennae and legs black, with weak iridescent reflections [?]. Wings hyaline [?], forewing venation brown.

Head. Quadrate and about twice [?] as broad as long in frontal view, in dorsal view transverse, distinctly wider than pronotum; vertex, inner and outer orbits smooth, without distinct sculpture (Fig. 12); ocelli forming a broad isosceles triangle, OOL longer than POL; frontal carina absent, scrobal cavity not deep and bounded by weak rounded keels (Fig. 13); malar sulcus distinct, about 0.2 times eye height; supraclypeal area glabrous, quadrate. Mandibles large and robust, right with 3 distinct teeth. Antenna: scape narrowly linear, weakly expanded apically [?], length about 5 times maximum width [?]; pedicel and funicular segments subequal in length, anellus about 0.2 times length of first funicular segment.

Mesosoma. Sculpture foveate-reticulate (Figs 13, 14) unless otherwise noted. Pronotum narrow, only about 0.2 times [?] length of mesoscutum (Fig. 13), without a distinct anterior carina, rounded laterad; mesoscutum and scutellum subequal in length; sidelobes of mesoscutum smooth along notauli; axillula large and triangular, with smooth median area delimited by large foveae (Fig. 14); scutellum only weakly vaulted, frenal line anteapical, the marginal rim forming the apex of scutellum, apex rounded (Fig. 14); metanotum large, straplike, length equal to frenum and marginal rim of scutellum combined, dorsellum indicated by ventral band of smaller foveae; propodeum with distinct median carina and smooth submedian areas delimited laterad by deep foveae (Fig. 14); prepectus large, a broad equilateral triangle, distinctly differentiated from and wider than the adjacent pronotum, with all three sides bordered with coarse punctures (Fig. 13). Forewing venation (Fig. 15): submarginal vein about twice marginal vein, postmarginal vein subequal in length to marginal vein (11:10); stigmal vein 0.4 times marginal vein and making an approximately 60 degree angle with marginal vein, stigma expanded with a distinct uncus.

Metasoma. Petiole inconspicuous, gaster closely associated with mesosoma, short and high in profile (Fig. 12), T2 with laterotergites and about as long as T3 and T4 combined. Sculpture glabrous.

Holotype. Male. Baltic Amber: Lutetian; purchased 2007 from Jens-Wilhelm Janzen AMNH Ba- JWJ687). Deposited in AMNH.

Etymology. From the Latin ( pisticus , ‘true, genuine’), a reference to this species as the first actual fossil species of Perilampus .

Additional Amber Specimens Examined. DCD has also seen specimens or photographs of four additional specimens of Perilampinae in Baltic amber, two in the collection of the American Museum of Natural History (examined, both Eocene [Lutetian], purchased from Jens-Wilhelm Janzen, AMNH B-JWJ- 121 and AMNH B-JWJ- 191) and two in the Staatliches Museum für Naturkunde Stuttgart (photographs courtesy of Lars Krogmann). These are not regarded as conspecific with P. pisticus and a thorough study of this material is currently underway. Interestingly, all 5 specimens have a very large and triangular prepectus, but only the holotype of P. pisticus has the short and triangular metasoma characteristic of extant species of Perilampus .

Baltic Amber Perilampus species were first reported in the literature over 120 years ago ( Brischke 1886; repeated in Larsson 1978) but were never formally described. This led to the premature dismissal of Brischke’s report by Peñalver & Engel (2006) because of the age of the work and lack of any subsequent specimens found in Baltic amber.

Phylogenetic Placement. This species is readily referable to the genus Perilampus (sensu Darling 1996) on the basis of the close association of the triangular prepectus with the pronotum (Fig. 13), short, triangular metasoma (Fig. 12), right mandible with 3 distinct teeth (cf. 2 in Chrysolampinae ), marginal vein only about twice as long as stigmal vein (Fig. 15, cf. at least 3.5 times in Chrysolampinae ), and absence of the synapomorphies of the other genera of Perilampinae (see Bouček 1978).

Not only is the amber species clearly referable to the genus Perilampus , but P. p i s t i c u s also shares a suite of characters with an informal group of extant Palaearctic species ( Bouček 1956, 1971), which we will refer to here as the Perilampus micans species group ( P. micans Dalman , P. aeneus (Rosseus) , P. ruschkai Hellen , P. maceki Bouček , P. cephalotes Bouček and P. polypori Bouček ). These species all have a relatively large and broad prepectus (64:6) with all three sides bordered by rows of coarse punctures and a distinct rudiment of the stigmal vein uncus (see Bouček 1956:94, couplet 1). Both of these characters are also present in P. p i s t i c u s (Figs 13, 15) and in Steffanolampus salicetum (Steffan) , with the latter considered as the most basal genus of Perilampinae because the prepectus, although large and triangular, is not fused with the pronotum ( Darling 1988). In addition, the frenum shape and orientation of the scutellar disc associate the amber species with both S. salicetum and P. m i c a n s. In all three species, the scutellar disc is not vaulted and the frenal line is complete dorsally and forms a carina that parallels the marginal rim of the scutellum (Fig. 14). In all other species of Perilampus and in the other genera of Perilampinae , the scutellar disc is vaulted over the frenum with the frenal line forming the apex of the scutellum (51:4). Based on outgroup comparison with Chrysolampinae , the configuration of the scutellum is plesiomorphic in the amber fossil, S. salicetum and P. micans , suggesting that these species are components of a basal grade of species that ultimately gave rise to the extant species of Perilampinae .

FIGURES 5–15. 5–11, Palaeocharis rex, female: 5, habitus; 6, antenna; 7, head and mesosoma, lateral view; 8, head, posterior view; 9, forewing and partial hindwing, ventral view; 10, gaster, apex in posterolateral view; 11, gaster, apex in posterior view. 12–15, Perilampus pisticus , male: 12, habitus; 13, head and anterior mesosoma, enlargement of 10; 14, scutellar complex and propodeum, dorsolateral view; 15, forewing venation, postmarginal vein to top. Abbreviations: anl = anellus; frl = frenal line; hys = hypopygial setae; lb = labrum; mps = multiporous plate sensilla; mrs = marginal rim of scutellum; pmv = postmarginal vein; stv = stigmal vein; vlf = 3rd valvifer.