Archaeocercus Simutnik, 2018

Simutnik, S. A. & Perkovsky, E. E., 2018, Archaeocercus gen. nov. (Hymenoptera, Chalcidoidea, Encyrtidae) from Late Eocene Rovno Amber, Zootaxa 4441 (3), pp. 543-548 : 544

Genus Archaeocercus Simutnik , n. gen.

Type species. Archaeocercus schuvachinae Simutnik , n. sp.

Diagnosis. Female. Body compact, slightly flattened. Head as wide as thorax in dorsal view and slightly wider than high in frontal view, hypognathous, with rounded occipital margin; surface of frontovertex smooth and shiny, sparsely punctate (Fig. 4); minimal distance between eyes about 2.4 times less than head width; ocelli small, in obtuse triangle; distance between posterior ocellus and eye margin (OOL) equal to posterior ocellar diameter; genae long, height of eye slightly exceeding malar space; facial cavity deep, with two antennal scrobes and high interantennal prominence; antennal toruli situated between oral margin and level of lower eye margin; distance between toruli approximately equal to length of malar space; malar space with complete but smoothed malar sulcus; eye without hairsprings; antenna 11-segmented (1:1:6:3); antennal scape slightly widened and flattened; pedicel conical, its length equal to combined length of flagellomeres 1–4; flagellum slightly flattened and widened toward apex, all flagellomeres transverse; F1 small, ringlike and conspicuously differentiated from subsequent segments; clava broad and expanded, with rounded apex, 3-segmented, wider than last flagellomere, about as long as 3 preceding flagellomeres combined; flagellum and clava covered with short hairs. Number of teeth of mandible unknown (not visible in specimen). MesΟsΟma. Pronotum in dorsal view short, transverse; mesoscutum flat, slightly wider than long, with short hairs; notauli reaching halfway across mesoscutum (Fig. 1: n); scutellum flat, rounded, slightly shorter than mesoscutum; interior axillar angles connected; mid coxa inserted at level with midline of convexly enlarged mesopleuron. Propodeum short. Appendages. Forewing without dark areas; linea calva without row of closing setae (filum spinosum) along distal margin; submarginal vein without dilation; marginal vein 4 times as long as wide; stigmal vein curved, slightly longer than marginal vein, without uncus; postmarginal vein 1.5 times as long as marginal vein; setae of marginal fringe short; tarsi five segmented; protibia with curved tibial spur (Fig. 4); mesotibial spur thick, equal in length to mid basitarsus. MetasΟma longer than mesosoma; tergites of gaster direct and parallel; cerci positioned on apex of metasoma (Fig. 1: c); hypopygium triangular, reaching metasomal apex (Fig. 2); ovipositor not protruding.

Male unknown.

Species composition. Type species.

Etymology. From Ancient Greek ἀρχαῖΟς (arkhaîos) - ancient, early, primitive, and “cerci”. Gender masculine.

Comparison and remarks. Among the extant genera of Encyrtidae , the apical position of pygostyles (at or near the apex of metasoma) is known in Quadrencyrtus Hoffer, 1953 ; EucΟccidΟphagus Hoffer,1963; Oriencyrtus Sugonjaev & Trjapitzin, 1974 ; Savzdargia Trjapitzin, 1979 , AphycΟides Mercet, 1921 (only A. clavellatus (Dalman 1820)) ; PsilΟphrys Mayr, 1876 ( Trjapitzin 1989; Simutnik 2005), and OesΟl Noyes & Woolley, 1994.

A comparison of ArchaeΟcercus with the extant genera with apically situated pygostyles is presented in Table 1. A strong similarity of some encyrtids preserved in Baltic amber to EucΟccidΟphagus and Oriencyrtus was recorded by Noyes & Hayat (1994). The new genus most resembles Oriencyrtus , but differs by the absence of the extension and uncus at apex of stigmal vein; mesotibial spur as long as mid basitarsus; hypopygium triangular, reaching metasomal apex (see Sugonjaev & Trjapitzin 1974) and flagellum 6-segmented. From Savzdargia , which also has long veins of the forewing, it differs by meeting axillae and transverse flagellomeres. ArchaeΟcercus clearly differs from most extant genera by the long and wide veins of the forewing ( Simutnik 2001, 2002, 2007, 2015b; Simutnik & Perkovsky 2015), and from PsilΟphrys and OesΟl (drawing in Noyes & Woolley 1994) by the absence of filum spinosum.

It is remarkable that the representatives of the majority of the extant genera with the apical position of cerci are parasitoids of Pseudococcidae , which are also known from Rovno amber ( Perkovsky et al. 2010), AphycΟides reared from PhysΟkermes ( Coccidae ), PsilΟphrys and OesΟl from Kermesidae ( Trjapitzin 1989; Noyes & Woolley 1994).

The new genus ArchaeΟcercus is likely most closely related to Quadrencyrtini Hoffer, 1953 and Oriencyrtini Sharkov, 1988. These taxa may appear to be basal groups for the Encyrtidae ( Noyes & Hayat 1994) , but their placement within Encyrtidae is difficult and is still discussed by encyrtidologists.

Some characters of the known fossil Encyrtidae are compared in Table 2. ArchaeΟcercus gen. n. is similar to the fossil genus EΟcencnemus (type species E. sugΟnjaevi), but differs by the absence of uncus in the stigmal vein, relatively more flattened body, notauli reaching halfway across mesoscutum, ovipositor not protruding, clava broad and expanded. The genus EΟcencnemus also includes two other species: E. vichrenkΟi and E. gedanicus , which were described, based on males, and attributed to the genus provisionally ( Simutnik & Perkovsky 2006; Simutnik 2007; Simutnik et al. 2014). However, they most probably will need to be placed in a separate genera in the future. The cerci of E. vichrenkΟi are also situated at the apex of the gaster, but notauli are absent in this species. The structure of the gaster of E. gedanicus is unknown; notauli are situated in the anterior half of mesoscutum similarly to ArchaeΟcercus, but the scutellum is convex and the stigmal vein bears a long uncus. SugΟnjaevia, which was also described based on male from Middle Eocene Sakhalinian amber ( Simutnik 2015a), has the stigmal vein with uncus, apical 1/3 of submarginal vein strongly widened and mesotibial spur shorter than mid basitarsus. The fourth fossil taxon with the same character is Sulia from Danish amber ( Simutnik 2015b), that differs from ArchaeΟcercus by propodeum with large convex lateral parts, the absence of notauli and large body size. Another species, which was described from Miocene Dominican amber, CΟpidΟsΟma archeΟdΟminica, belongs to an extant genus of the subfamily Encyrtinae ( Zuparko & Trjapitzin 2014).