Butiokeras costae, Burks & Heraty, 2020

Burks, Roger A. & Heraty, John M., 2020, First described fossil representatives of the parasitoid wasp taxa Asaphesinae n. n. and Eunotinae (Hymenoptera: Chalcidoidea: Pteromalidae sensu lato) from Eocene Baltic amber, Journal of Natural History 54 (9), pp. 801-812 : 808

Butiokeras costae n. sp.

( Figure 1 (d,e))

http://www.zoobank.org/ urn:lsid:zoobank.org:act:E96B18F5-E685-40F8-A9AB-68CC459E907C

Description. Male: Length 1.34 mm (n = 1). Most important features reported in the generic description, but a few presumably specific features mentioned here.

Head. Flagellomeres slightly broader than long, each with 1 row of multiporous plate sensilla [mentioned here because Eunotus species vary in the number or rows per segment].

Mesosoma very weakly arched anteriorly and posteriorly, but flat at scutoscutellar sulcus. Propodeum laterally with a strongly sculptured elevation. First tarsomere of each leg almost as long as the others combined.

Material examined

Baltic amber inclusion: Eocene, Jens-Wilhelm Janzen coll. [1M #, AMNH: UCRCENT305754 ]. Deposited in AMNH. Small fractures near the wings block view of some structures .

Etymology. After the Latin noun costa, meaning rib. Genitive case.

Discussion. Females are unknown but presumably are similar to the known male except for the antenna and gaster. Butiokeras is classified in Eunotini, near Eunotus , because it shares features of the male flagellum and fore wing with extant species of Eunotus . The flagellomeres in males are distinctive, each with one or two rows of multiporous plate sensilla that give the appearance of ribs because they are conspicuously elevated and in total extend about the same length as their respective flagellomeres. These antennal features are best known from the Eunotus kocoureki Bouček species group, which is also defined by the presence of three mandibular teeth instead of two ( Bouček 1972). Placement in the E. kocoureki species group was considered, but rejected because Butiokeras costae lacks a vertexal carina and possesses a short Gt 1. Either of these character states would be unique within Eunotus , and the occurrence of both together and consideration of the fossil ’ s age suggest that Butiokeras is best treated as a distinct genus.

Other genera of Eunotini are distinctly different from Butiokeras . Epicopterus Westwood and Mesopeltita Ghesquière differ in having a strong incision in the fore wing near the marginal vein base. Scutellista Motschulsky is known for its elongate mesoscutellum which typically extends dorsally over the metanotum, propodeum, and part of the gaster. Cephaleta Motschulsky and the apparently closely related Cavitas Xiao & Huang also have a relatively short Gt 1, but they also have a relatively smooth and glossy mesoscutum and mesoscutellum instead of the fine raised sculpture present in Eunotus ( Xiao & Huang 2001) and Butiokeras .

Figures

Figure 1. (a–c) Coriotela lasallei n. gen., n. sp. holotype female: (a) Body, dorso-lateral; (b) Head, mesosoma, and anterior part of metasomal, lateral, frl = frenal groove, occ = occipital carina. (c) Fore wing, clv = clava, clavomeres numbered. (d,e) Butiokeras costae n. gen., n. sp. holotype male: (d) Body, dorso-lateral; (e) Body, ventro-lateral.