Teloganella gurhaensis, Agnihotri & Chandra & Shukla & Singh & Mehrotra, 2020

Agnihotri, Priya, Chandra, Kajal, Shukla, Anumeha, Singh, Hukam & Mehrotra, Rakesh C., 2020, First fossil record of a nymph (Ephemeroptera, Teloganellidae) from the Indian subcontinent, Zootaxa 4838 (1), pp. 137-142 : 138-141

Teloganella gurhaensis sp. nov.

( Figs 2 , 3 )

Diagnosis. Body with defined proportions, flattened pronotum and mesonotum, eyes widely separated, fore-femora greatly expanded, claws without denticles, fore-femora margined with bristle-like setae, elongated abdomen, three caudal filaments well-developed.

Holotype. BSIP specimen no. 41813, Late Paleocene-early Eocene, Palana Formation, Gurha lignite mine, Bikaner district , Rajasthan.

Etymology. The specific name is given after the locality Gurha, where the fossil was discovered.

Description. Nymph impression in dorsal position; satisfactory preservation quality of the specimen; body 8.4 mm in length; head 1 mm long with lateral location of eyes and fringe of setae over the head capsule, antennae visible; prothorax 0.6 mm divided into two lobes, hard sclerite impression over the dorsal surface; fore-femora wider than long (FF L - 0.92 mm; FF R - 0.8 mm), setae on the inner and outer margins of femur and tibia, single tarsal claw without denticles; mesothorax 1.4 mm, forewing pads slightly visible, left and right mid-tibia margined with setae; abdomen 3.4 mm, segments I to X visible, Xth segment bearing 3 caudal filaments (cerci- 2 mm), filaments 1/4 th of the body length, median filament visible, slender with no spines; location of gills not discernible.

Affinities. The fossil exhibits morphological similarities with modern Teloganella studied from India and Malaysia. Expanded fore-femora are considered a convergence trait that has evolved through diverse taxa of Pannota ( McCafferty & Wang 2000) and also justifies its convergence with Teloganodidae . Row of well-developed broad setae on the larval fore-femora distinguishes the Teloganellidae from the other families of Ephemeroptera ( Kluge 2004) . This trait also suggests co-relation with the Tricorythidae and is also considered as a homophyly (resemblance due to common ancestry) both in Pannota and other mayflies under similar environmental conditions. Teloganellidae belongs to the superfamily Ephemerelloidea which also encloses Ephemerellidae , Melanemerellidae , Teloganodidae and Tricorythidae ; however, the affinities and the position of Teloganella are still unsolved ( Sites et al. 2001, Soldan 2001, Sartori et al. 2003, Kluge 2004, Ogden et al. 2009).

A number of fossil insects from the early Eocene amber belonging to different families have been described from the Indian subcontinent ( Grimaldi & Singh 2012, Stebner et al. 2017, Zakrzewska et al. 2017, Kania et al. 2018, and reference therein). The present fossil is the first record of a mayfly from the Indian subcontinent, and is described as Teloganella gurhaensis Agnihotri et al. , sp. nov.

Figures

FIGURE 2. A–D. Teloganella gurhaensis Agnihotri et al., sp. nov. A. Fossil insect in reflected light. B. Enlarged view of the upper half showing fore-femora, mid-femora and mid-tibia. C. Enlarged head portion with setae (red arrows). D. Enlarged lower half with abdominal segments (red arrows) and terminal filaments (black arrows).

FIGURE 3. Numbered abdominal segments of Teloganella gurhaensis Agnihotri et al., sp. nov.