Galloatherix incompletus, Nel, André, Ploëg, Gaël De & Perrichot, Vincent, 2014

Nel, André, Ploëg, Gaël De & Perrichot, Vincent, 2014, The first ibis fly in mid-Cretaceous amber of France (Diptera: Athericidae), Zootaxa 3768 (5), pp. 591-595 : 592-593

Galloatherix incompletus sp. n.

( Figure 1 )

Type material. Holotype specimen ARC 130, mounted on slide #40095, stored in the palaeobotanical collection, MNHN, Paris. The fossil is included in a triangular piece of amber with dimensions 19.5 × 8.5 × 3.8 mm, with syninclusions of five other fossil flies and numerous marine dinoflagellates.

Etymology. Named after the incomplete state of preservation of the type specimen.

Type locality and age. Font-de-Benon quarry, 0.8 km east of Archingeay, Charente-Maritime, France. Cretaceous, Uppermost Albian–Lowermost Cenomanian (ca. 100 Mya), lithological subunit A1sl-A.

Diagnosis. As for the genus.

Description. Wing hyaline, preserved part 2.47 mm long, 1.19 mm wide; apical parts of veins R2+3 and R1 very close; R2+3 weakly curved posteriorly; vein R4 terminated before wing apex, distally straight, not sigmoidal; R4 and R5 rather parallel, not significantly diverging distally; basal cell br comparatively long, with distal end extending as far as level of Sc termination; veins M1, M2 and M3 as long as cell dc, so that cell m2 is quite long, longer than dc; discal cell 0.55 mm long, 0.16 mm wide; cell m3 widely opened at margin; veins M3 and CuA1 weakly convergent; anal cell closed; stigma very dark, well developed beneath vein R1.

Discussion. The vein R2+3 ending very near to R1 (marginal cell closed) is diagnostic and synapomorphic for the Athericidae ( Zloty et al. 2005) . Nagatomi (1985) proposed keys to the genera based on body structure and male genitalia and attempted the first phylogenetic tree. We could compare our fossil based only on the limited number of preserved structures pertaining to the wing venation only.

The cell m3 widely open at the margin excludes affinities with the genera Xeritha Stuckenberg, 1966 and Suraginella Stuckenberg, 2000 ( Stuckenberg 1966, 2000). In Suragina Walker, 1858 and Ibisia Rondani, 1856 , this opened cell is clearly narrowed near the posterior wing margin and the cell m2 is clearly shorter than in Galloatherix gen. n. ( Stuckenberg 1973). The same difference occurs in Asuragina Yang & Nagatomi 1992 , plus the presence of a sigmoidal R4 ( Yang & Nagatomi 1992). In Dasyomma Macquart , cell m3 is as opened as in Galloatherix but the radial fork arises distal to base of M1 while it is opposite in Galloatherix . Trichacantha Stuckenberg, 1955 , has an open anal cell, unlike Galloatherix ( Stuckenberg 1955, 1974). In Atrichops Verrall, 1909 , the radial fork is distinctly basal to base of M1 ( Nagatomi 1979a, b). In Atherix Meigen, 1803 , and Pachybates Bezzi, 1926 , cell m2 is also clearly shorter than in Galloatherix ( Bequaert 1921, Bezzi 1926). The Baltic amber Succinatherix Stuckenberg, 1974 differs from Galloatherix in the length of M3 ranging from 42 to 72% of the length of the discal cell, while they are of nearly of the same length in Galloatherix ( Stuckenberg 1974) . The Early Cretaceous genus Athericites Mostovski et al., 2003 has also a longer discal cell than Galloatherix , plus vein R4 is more sigmoidal than in Galloatherix ( Mostovski et al. 2003). The Early Cretaceous genus Sinocretomyia Zhang, 2012 shares with Galloatherix a discal cell of nearly the same length as M3, but they differ in the presence of a strongly sigmoidal R2+ 3 in the former genus ( Zhang 2012). The Cretaceous genus Palaepangonius Ren, 1998 , originally in Tabanidae , but transferred to Athericidae by Zhang (2012), has the discal cell distinctly longer than M3 ( Ren 1998).

Modern athericid larvae are aquatic in lotic habitat, living in freshwater and feeding on larvae of Chironomidae , while the adults are flying among the vegetation bordering streams. The presence of an athericid in a piece of Charentese amber, together with several Microphorites —flies living as adult in wet sandy environments ( Nel et al. 2004), and dinoflagellates adapted to transitional marine–freshwater environments ( Masure et al. 2013), supports the model of a coastal amber forest growing in a mosaic of brackish (estuary or mangrove) and freshwater (ponds) ecosystems with marine inputs (Perrichot et al. 2010, Perrichot & Girard 2009, Girard et al. 2009). It also adds to the diverse assemblage of aquatic and riparian organisms already identified in the paleobiota from Charentese amber, e.g. gerromorph and schizopterid bugs, tanaids, marine diatoms, testate amoebae, etc. ( Perrichot et al. 2005, 2007, 2010, Girard et al. 2008, Schmidt et al. 2010, Girard 2012).

Figures

FIGURE 1. Galloatherix incompletus gen. n., sp. n. holotype MNHN 40095, wing (scale bar = 0.5 mm).