Some notes on Prophalangopsis obscura (Walker, 1869)

Reconstructed image and song of Prophalangopsis obscura from Woodrow et. al. (2022)

History of the genus Prophalangopsis and the type specimen of Tarraga obscura

The genus Tarraga was first erected by Walker (1869), unfortunately using a preoccupied name the same author erected a year previously within the Blattodea (Walker, 1868). This was later corrected by the nomen novum Prophalangopsis Walker, 1871. The type species is Tarraga obscura Walker, 1869. The genus has remained accepted and monotypic ever since, indicating the unique interest of its sole species, which has received considerable interest in relation to the evolutionary history of the Ensifera (e.g. Zeuner, 1939; Desutter-Grandcolas, 2003). The enigmatic nature of the type specimen has been compounded by no further confirmed specimens being discovered in over 150 years.

The precise origins of the type specimen remain obscure, with previous literature references mentioning a broad geographic area broadly synonymous with the extent of the former British India at the time of collection (e.g. Hindostan, E. Indies), and that the specimen was presented by Sir John Hearsey (sometimes misspelt as Hearsay). The Natural History Museum’s Accession Register shows that the specimen was one of eight Orthopteran specimens presented by Major-General Sir John Hearsey in 1861, with an indication that the combined lot was sent from the city of Barrackpore in the current Indian state of West Bengal.

The text in the Accession Register gives more precise locality data for some of the other specimens from this lot, but not for the type specimen of P. obscura, “Generally ticketed E. Indies. Some were marked as from Mussoorie when they are so ticketed - others Punjaub. They were collected by the Donor at different stations one specimen, Minetra Gambrisius is from the Andamen Islds.”

With the exception of the single specimen from the Andaman Islands, the remaining specimens with known localities are all from northern states of modern India, close to its international borders (Pakistan, Tibet, Nepal). Hearsey was in the cavalry of the British Indian Army and was at Barrackpore at the start of the Indian Mutiny in 1857. No correspondence was found in the archive catalogue of the Natural History Museum, although prior botanical correspondence (1840s) with William Jackson Hooker is held by the Royal Botanic Gardens Kew. These earlier letters are from modern day Pakistan and northern India.

The combined historical evidence suggests that the type specimen of P. obscura was collected in northern India, although it is at present not possible to give a more precise location. Further research on where Hearsey was stationed prior to 1861 might help to identify the type locality, although as there is no date of collection (unless one is found in currently unknown correspondence) this knowledge would most likely serve to reduce the search area rather than fix a location.

If the female specimens described in Liu et al (2009) are confirmed to be P. obscura then the known range may be extended from northern India to include Tibet. Further collections from this area to confirm or otherwise the association between males and females would be very valuable.

The holotype is currently in very fragile condition and must be handled with unusual caution. Zeuner (1939) states that the specimen was originally set in a resting position restricting Walker and Saussure to studies of the left elytron, however both left wings are figured for the first time in Saussure (1898). At a later date the specimen was re-set with both elytra spread (Zeuner, 1939 suggests this may have been done by Karny). The left elytron has had a substantial tear since at least 1939 (Zeuner). The photograph of the specimen in Zeuner (1939) shows that the specimen has subsequently lost much of the apex of the right elytron as well as the left fore-tibia.

References

Desutter-Grandcolas L (2003) Phylogeny and the evolution of acoustic communication in extant Ensifera (Insecta, Orthoptera). Zool. Scripta 32(6):538

Saussure H de (1898) Analecta Entomologica I. Orthopterologica. Revue Suisse de zoologie.

Walker F (1868) Catalogue of the Specimens of Blattariae in the Collection of the British Museum

Walker F (1869) Catalogue of the Specimens of Dermaptera Saltatoria in the Collection of the British Museum

Walker F (1871) Catalogue of the Specimens of Dermaptera Saltatoria in the Collection of the British Museum Supplement

Zeuner FE (1939) Fossil Orthoptera, Ensifera

Research work

• Reviving the sound of a 150-year-old insect: The bioacoustics of Prophalangopsis obscura (Ensifera: Hagloidea)
  Determining the acoustic ecology of extinct or rare species is challenging due to the inability to record their acoustic signals or hearing thresholds. Katydids and their relatives (Orthoptera: Ensifera) offer a model for inferring acoustic ecology of extinct and rare species, due to allometric parameters of their sound production organs. Here, the bioacoustics of the orthopteran Prophalangopsis obscura are investigated. This species is one of only eight remaining members of an ancient family with over 90 extinct species that dominated the acoustic landscape of the Jurassic. The species is known from only a single confirmed specimen–the 150-year-old holotype material housed at the London Natural History Museum. Using Laser-Doppler Vibrometry, 3D surface scanning microscopy, and known scaling relationships, it is shown that P. obscura produces a pure-tone song at a frequency of ~4.7 kHz. This frequency range is distinct but comparable to the calls of Jurassic relatives, suggesting a limitation of early acoustic signals in insects to sonic frequencies (<20 kHz). The acoustic ecology and importance of this species in understanding ensiferan evolution, is discussed.