Nymphes georgei, Archibald, Bruce, Makarkin, Vladimir N. & Ansorge, Jörg, 2009

Archibald, Bruce, Makarkin, Vladimir N. & Ansorge, Jörg, 2009, New fossil species of Nymphidae (Neuroptera) from the Eocene of North America and Europe, Zootaxa 2157, pp. 59-68 : 60-62

Nymphes georgei sp. nov.

Fig. 1 A–B

Etymology. The specific epithet is formed from the surname of Steven George, collector of the holotype, in recognition of his generous contribution to science in the donation of this specimen.

Holotype. Specimen SR 09-07-08 (part only), collected by Steven George, and deposited in SRIC. A wellpreserved, incomplete hind wing.

Type locality and horizon. Tom Thumb Tuff Member of the Klondike Mountain Formation, exposure A0307, Republic, Washington, U.S.A.; Ypresian.

Diagnosis. Hind wing separable from those of N. myrmeleonoides , N. modesta , N. paramyrmeleonides by absence of tornus, subcostal crossveins; from those of N. aperta by branches of MP originated at more obtuse angle, area between distal portion of CuA, MP, then MP1 broader; from those of N. nigrescens by distal origin of Rs1, slightly distal to termination of CuA [Rs1 originated much proximal to termination of CuA in N. nigrescens ].

Description. Hind wing elongate, without tornus, with apex shifted posteriad; preserved portion 27 mm long (estimated complete length about 34–35 mm), 8.2 mm wide. Trichosors prominent along entire preserved margin: one between each vein tip apically along posterior margin, many (up to about five) between veinlet tips along anterior margin, posterior margin in mid- and basal wing. Each vein/veinlet tip thickened like trichosors. Macrotrichia along veins rather short. Costal space narrow. Subcostal veinlets simple, perpendicular to Sc basally, bent apically. Sc+R1 entering margin far beyond apex; veinlets of Sc+R1 deeply forked, each branch with shallow marginal fork; two crossveins preserved between veinlets of Sc+R1. Subcostal space narrow, without crossveins. R1 space broad, with numerous crossveins arranged rather regularly. Rs probably originated near wing base, with 10 branches dichotomously branched distally. Rs1 originated far distant from wing base, rather profusely branched distally. MA slightly concave, somewhat arced, only few branched distally. MP slightly convex, markedly arced distal to its proximal branch, with seven branches, partly dichotomously branched. MP space triangular, enclosed by distal portion of MP, basalmost branch of MP. Radial, medial crossveins numerous, arranged irregularly. MP, CuA approach to each other toward wing base; several crossveins between them. CuA probably slightly concave (poorly preserved), pectinately branched (two branches preserved); each branch connecting by crossvein to other (three crossveins preserved). CuP, anal veins not preserved. Membrane hyaline.

Comments. The extant genera of Nymphidae are divided into the morphologically distinct Nymphesgroup ( Nymphes , Nesydrion Gerstaecker, 1885 a, Austronymphes ) and Myiodactylus- group ( Myiodactylus Brauer, 1866 , Osmylops Banks, 1913 , Nymphydrion Banks, 1913 , Norfolius Navás, 1922 ) ( New 1984). Formerly, the Myiodactylus- group was considered to constitute a separate family, the Myiodactylidae (Handlirsch 1906–1908; Withycombe 1925; Tillyard 1926), and has subsequently been treated as a subfamily of Nymphidae ( Henry 1982; Makarkin 1990).

Nymphes georgei belongs confidently to the Nymphes -group by the following hind wing features: the MP space has a characteristic triangular area enclosed by the distal portion of MP and the basal-most branch of MP [absent in Myiodactylus- group]; Rs1 is originated distant from wing base [relatively close to wing base, much proximal to termination of CuA in Myiodactylus- group]; costal space is narrow [broad in Myiodactylusgroup]. Fortunately, the venation of hind wings of all species of Nymphidae (both fossil and extant, except the Early Cretaceous Olindanymphes makarkini Martins-Neto, 2005) is well known, allowing some confidence in its generic affinity.

All preserved character states indicate that the hind wing venation of this species is indistinguishable from that of Nymphes species. Indeed, the hind wing venation of Nymphes possesses a distinctive combination of the long stem of Rs (i.e., Rs1 is originated distally) and the presence of crossveins between branches of CuA. The venation of N. nigrescens differs greatly from that of other species of the genus. For example, Rs originates much more distally in its hind wing, costal crossveins are present in the apical portions of both wings, and there are no crossveins connecting branches of CuP in the forewing. New (1982) mentioned that this species “may eventually be separated into a new genus” (p. 718). The genus Nymphes is also heterogeneous for the presence/absence of subcostal crossveins in both wings and M is either deeply forked or simple in the forewing. While understanding that further examination might then indicate that Nymphes should be broken into smaller genera, this is outside of the scope of this study, and here, we assign N. georgei to this genus as currently defined. However, the Nymphes affinity of this new species should be considered formally tentative, as the specimen is represented by only an incomplete hind wing; we should not exclude a venational convergence between this fossil species and species of Nymphes .

The venation of N. georgei is most similar to that of N. aperta in wing shape, size and many venational details, including the absence of the subcostal crossveins (cf. Figs. 1 B and 1C).

Other extant genera have somewhat different venation. For example, all species of Nesydrion have numerous subcostal crossveins and do not possess any crossveins between the branches of CuA [contrary in N. georgei ]; the single species of Austronymphes has these crossveins, but the stem of Rs is short. Also, the hind wings of these two genera are broader than that of N. georgei in association with the rather distinct tornus in most species. The venation of all known fossil genera is considerably different from that of N. georgei .

Nymphes georgei is significant in that it shows that this genus (or one very close), currently found only in Australia (continental and Tasmania), was present in the Eocene of North America. This is an emergent pattern among some insects known from Eocene Republic and other Okanagan Highlands fossil localities, e.g., bulldog ants ( Hymenoptera : Formicidae : Myrmeciinae ; Archibald et al. 2006), and mastotermitid termites ( Isoptera : Mastotermitidae ; Wilson 1977). This is in accord with a broader pattern of a number of insects that had a Northern Hemisphere distribution in the Mesozoic and/or Eocene, and are today restricted to the Australian region, e.g., Tettigarctidae (Hemiptera) (Menon 2005); Plectrotarsidae (Trichoptera) ( Sukacheva & Jarzembowski 2001); the genus Peradenia Naumann et Masner, 1985 and its family Peradeniidae (Hymenoptera) ( Johnson et al. 2001); and, indeed, other biota, e.g., the family and genus level similarities between the Lutetian flora of Messel, Germany, and that of the modern Australian region (Burrows 1998). This is the first fossil record of Nymphes , and so details of its change in distribution through the Cenozoic remain obscure ( Nymphidae is also now established in North America for the first time; the biogeographic history of the family will be examined in a future work).

Figures

FIGURE 1. Hind wings of Nymphes georgei sp. nov. and N. aperta. A, photograph of holotype specimen SR 09 - 07 - 08. B, N. georgei sp. nov., holotype specimen SR 09 - 07 - 08. C, N. aperta (re-drawn from New, 1982: Fig. 42; vein labelling is ours). Scale bar = 5 mm (for A – B; C, scale not provided by New, 1982).