Vastaplatyura electrica Solórzano Kraemer & Evenhuis, 2008

Solórzano Kraemer, Mónica M. & Evenhuis, Neal L., 2008, The first keroplatid (Diptera: Keroplatidae) species from the Lower Eocene amber of Vastan, Gujarat, India, Zootaxa 1816, pp. 57-60 : 57-59

Vastaplatyura electrica Solórzano Kraemer & Evenhuis , gen. nov., sp. nov.

( Figs. 1–5)

Diagnosis: Vastaplatyura is most similar to the orfeliine genera Trigemma Hardy, 1960 , Pyrtulina Matile, 1977 , and Asynaphleba Matile, 1974 on the basis of the common possession of regular rows of setae on the tibiae and the bare longitudinal strips on the mesonotal disc. It can be separated from Trigemma by the absence of setae on the laterotergite (present in Trigemma ) and separated from Pyrtulina and Asynaphleba by the possession of a single spur on the hind tibia (2 spurs present in Pyrtulina and Asynaphleba ). Using the key in Søli et al. (2000), Vastaplatyura keys to Laurypta Edwards, 1929 but it is easily distinguished from it by the presence of the bare areas on the mesonotum (the mesonotum is uniformly setose in Laurypta ).

Type species: Vastaplatyura electrica , by monotypy.

Description: Lengths: Body: 2.3 mm; wing: 2.4 mm. Female. Head. Occiput brownish black. Three ocelli near middle of frons, all subequal in size. Frons, face, and clypeus dark brown. Antenna with scape and pedicel discoid, brownish; flagellomores yellowish, cylindrical. Flagellomere segment 1 widest (length subequal to width), tapered to narrowest segments 12 and 13 (length ca. 2.5 times width), palpus brownish ( Fig. 2).

Thorax. Prothorax brown; mesoscutum, scutellum, and mediotergite yellow, brown on extreme lateral and anterolateral portions of mesoscutum. Mesoscutum with short erect dark hairs, bare longitudinal strips admedially and supra-laterally. Pleurae yellow, bare. Mediotergite and laterotergite bare. Halteres pale yellow.

Legs. yellowish brown. Spurs black, single on each tibia; those on fore and mid legs minute, on hind leg very long. Tibiae with regular rows of setae.

Wing ( Fig. 5). Grayish yellow hyaline. Macrotrichia present on upper surface on radial veins, absent on M and Cu veins and wing field. Vein R 4 ending in costa beyond end of R 1. Anal vein incomplete. Anal lobe well developed.

Abdomen. Yellow, with black color laterally; black hairs on all segments, longest on segments VI and VII ( Fig 3).

Type: Holotype female from India ( Fig. 1–5): MLGDLU/NS/1002. Housed in the Department of Geology at Lucknow University, Lucknow, India.

Etymology: The generic name derives from Vasta, which refers to the Vastan amber deposits and - platyura , which refers other orfeliines related to Platyura , sensu lato. The specific name derives from the Greek, elektra; which refers to amber.

Discussion: The continental history of India is still under discussion and the question if India really existed as an isolated continent during the late Cretaceous and Paleocene still remains.

Currently, there are three different theories about the position of India in the last 65 my. The standard “biotic ferry model” showing India as an isolated island, the “ land bridge model”, which incorporates a connection with Africa, and another “biotic bridge model”, which includes connections to Asia, Africa and Madagascar (e. g. Hedges 2003). Together with the “biotic ferry model” the “out-of-India ” theory is also discussed, which suggests an origin of Asian biotic elements from Gondwanaland and the rafting of the organisms from the Indian plate to Asia ( McKenna 1973).

The fossil mammals of the Vastan mine represent mainly endemic fauna suggesting the isolation of the Indian landmass at least over the last 65 my. However, some Holarctic elements are also present advocating a possible early Tertiary out-of-India vertebrate dispersal ( Rana et al 2005, Bajpai et al. 2005, Smith et al. 2007). The fossil record of several other organisms like sauropods dinosaurs, frog families, anguid lizards, boid snakes, pelomedusid turtles, and mammals among other examples (for a review of the historic biogeography of India see Briggs 1989) give strong evidence for land bridges or island chains between India and Asia as well as India and the Seychelles, Madagascar, and Africa during the Late Cretaceous. This is also supported by the rate of movement of the Indian plate and the notable drop of the sea level in the late Cretaceous ( Briggs 2003), On the other hand recent organisms like frogs, Ichthyophiidae (Asiatic tailed caecilians) and other amphibians instead support the biotic ferry model ( Bossuyt & Milinkovitch 2001, Conti et al. 2002, Gower et al. 2002, Hedges 2003). Until now, no insects or arthropod fossils have been studied with the purpose to help resolve this problem. If India was an isolated continent during most of the Cretaceous and the Paleocene, its high extant and fossil biodiversity with a distinctive endemism should also be reflected by arthropod examples.

Despite the differences in biodiversity between regions the Keroplatidae from the Oriental Region are poorly investigated, with 108 species previously described. The Neotropical Region is better explored (203) and even better the Palearctic Region (243) ( Evenhuis 2006). However the precise relationship of the new genus presented in this paper with other orfeliine genera cannot be definite placed here without a cladistic analysis of all the Orfeliini .

Vastaplatyura shares synapomorphic characters with the following extant genera: Laurypta , Trigemma , Pyrtulina , and Asynaphleba . The actual distribution of these extant genera is very broad. Species of the genus Laurypta are distributed in the Afrotropical region of the Seychelles and Cameron, in the Oriental region in Korea, Malaysia, and Sri Lanka, and in the Australasian/Oceania region in Palau. Species of the genus Trigemma are endemic to the Hawaiian Islands. Species of the genus Pyrtulina are distributed in the Australasian/Oceanian region in New Caledonia and in the Afrotropical region in Madagascar. Species of the genus Asynaphleba are distributed in the Afrotropical region of South Africa.

Living families and some extant genera of Mycetophilidae appeared in the Cretaceous ( Grimaldi et al. 2002) and by the Eocene they became very abundant and diverse inhabitants of moist temperate forest ( Grimaldi & Engel 2005).

Vastaplatyura appears to be endemic to the Indian subcontinent and may not have ranged further from India. Thus Vastaplatyura would support a biotic ferry model for India in the last 65 my. However, in addition to further studies on the characters shared among the five genera, more studies on the extant and fossil biodiversity of insects from India, Africa and Asia are needed before any more conclusive comments can be made about hypothetical origins and ranges of this genus or the fossil Vastan arthropod fauna.