Bruchomyiinae, Alexander, 1921

Dale E. Greenwalt, Daniel J. Bickel, Peter H. Kerr, Gregory R. Curler, Brian V. Brown, Herman de Jong, Scott J. Fitzgerald, Torsten Dikow, Michal Tkoč, Christian Kehlmaier & Dalton De Souza Amorim, 2019, Diptera of the middle Eocene Kishenehn Formation. I. Documenting of diversity at the family level, Paleontologia Electronica 22 (2), No. 50, pp. 1-56 : 13-14

Bruchomyiinae incertae sedis

Figure 8

Holotype. USNM 619952 , deposited in the Department of Paleobiology , National Museum of Natural History (NMNH), Smithsonian Institution , Washington, District of Columbia, USA. Type horizon. Middle Eocene Coal Creek Member, Kishenehn Formation.

Type locality. Disbrow Creek site, Middle Fork of the Flathead River (Pinnacle, Montana, USA).

Differential diagnosis. Based only on the wing, Bruchomyiinae is distinguished from all other Psychodidae by the following combination of character states: measured at their greatest value, distance from base to apex at least three times that of anterior to posterior wing margin; five radial veins present; base of R 1 prominent, thickened, setose; apex of CuA reaching wing margin.

Description

Two wings (Figure 8.1-2), the left wing missing a portion of it postero-apical end, attached to remnants of the mesosoma.

Wings. Wing length, 3.08 mm, 1.02 mm wide; macrotrichia not present/preserved. No costal breaks beyond base. Distances from wing base - Rs fork - Sc terminus - r-m - R 2+3 fork - wing apex are 1.08, 0.22, 0.12, 0.25 and 1.35 mm; ratio of the length of the stem of R 2+3 to the length of the fork is 0.5. Apex of wing between R 4 and R 5. M 2 originating at the end of second basal cell (i.e., at r-m).

Allotype. Sex unknown.

Syncompressions. None

Remarks

Approximately 150 genera and 3,020 species of Psychodidae have been described ( Pape et al., 2011); although estimates suggest the actual diversity is much greater ( Wagner and Ibañez-Bernal, 2009). In addition to Bruchomyiinae , there are an additional six subfamilies including Datziinae Stebner et al., 2015 , which are known only from fossil species. Despite their occurrence in a variety of habitats and frequent numerical abundance ( Brown, 2005; Wagner and Ibañez-Bernal, 2009), most psychodids are poorly known. In contrast, many phlebotomine species are well known due to their role as vectors of Leishmania Ross, 1903 spp. and other disease agents.

There is a rich fossil record for psychodids dating to the early Jurassic ( Ansorge, 1994) and possibly the late Triassic ( Fraser et al., 1996; Blagoderov et al., 2007); however, Blagoderov et al. (2007) note that Triassopsychoda olseni Bla- goderov and Grimaldi in Blagoderov, Grimaldi and Fraser, 2007 has a unique wing veination with several plesiomorphies and its relationship to other psychodomorphs is unclear. As summarized by Stebner et al. (2015), approximately 30 genera and more than 100 fossil psychodid species have been described, yet, like the extant fauna, many species remain undescribed.

Bruchomyiinae , with six genera, 53 extant species and eight fossil species ( Curler and Jacobson, 2012; Wagner and Stuckenberg, 2012; Wagner and Stuckenberg, 2016; Stebner et al., 2015), is among the less-taxonomically diverse subfamilies of Psychodidae . Adults of this group are readily distinguished from other psychodids by their relatively large size as well as the diagnostic wing characters provided previously. Male and female genitalia characters are important for distinguishing genera and species ( Curler and Jacobson, 2012; Wagner and Stuckenberg, 2016).

Fossil Bruchomyiinae are described from Baltic, Dominican and Burmese amber with the oldest specimen preserved in middle Cretaceous amber from Myanmar ( Schluter, 1978; Stebner et al., 2015; Wagner, 2006; Wagner and Stuckenberg, 2012; Wagner, 2017). All fossil species of this subfamily, previously placed in Nemopalpus Macquart, 1838 , were recently transferred to other genera ( Wagner, 2017). Baltic amber species are placed in Palaeosycorax Meunier, 1905 or Hoffeinsodes Wagner, 2017 while Burmese amber species are grouped in Palaeoglaesum Wagner, 2017 and Dominican amber species are included in Boreofairchildia Wagner and Stuckenberg, 2016 .

The wing venation of the Kishenehn specimen is similar to, for example, extant Bruchomyia Alexander, 1921 , species and fossil Hoffeinsodes species in that M 2 originates at the level of r-m. Regardless, this character state occurs in other extant and fossil genera ( Wagner and Stuckenberg, 2012; Wagner personal commun.); therefore, it may be a plesiomorphy within the subfamily. Considering the ambiguity of wing venation and the lack of other preserved characters, it is impossible to identify the Kishenehn specimen beyond subfamily.

This is the first compression fossil of a bruchomyiine species to be discovered and it is the first fossil of this subfamily from the Nearctic Region to be reported. With the exception of Notofairchildia zelandiae Alexander, 1921 (New Zealand), and N. stuckenbergi Wagner, 2012 (Chile, Valdivia) ( Wagner and Stuckenberg, 2012), extant Bruchomyiinae are apparently absent from the temperate zone.

Nonetheless, this new record and the growing number of species described from various ambers ( Wagner, 2006, 2017) indicate that the group was once more widespread and morphologically diverse. In addition to the bruchomyiine specimen, psychodids taken from the Kishenehn Formation include over 20 specimens of Psychodidinae with potential for further study.

Figures

FIGURE 8. Bruchomyiinae sp., USNM 619952. 1, Right wing; 2, Drawing of the right wing. Scale bar equals 1.0 mm (1).