Review of the type series of Pterocles exustus Temminck, 1825 (Aves, Pterocliformes, Pteroclidae) and designation of a lectotype

Abstract The type locality of Pterocles exustus Temminck, 1825, is ‘West coast of Africa, Egypt and Nubia’. This is problematic because it includes the type locality of Pterocles exustus floweri (Nicoll, 1921), which is Fayum, Egypt. In the interest of clarification and to preserve stability of nomenclature, a non-Egyptian specimen from the type series of Pterocles exustus is designated as lectotype of the taxon, and the type locality is restricted to Senegal.


Introduction
The Chestnut-bellied Sandgrouse (Pterocles exustus) is a sedentary and nomadic species that naturally inhabits bare semi-deserts from Senegambia and Mauritania to Egypt, Sudan, Ethiopia and Somalia, as well as in Kenya, Tanzania, Arabian Peninsula and further east to Iran, Pakistan and India (del Hoyo and Collar 2014: 216). Six subspecies are currently recognized, with ranges as follows (Dickinson andRemsen Jr 2013: 81, del Hoyo andCollar 2014: 216): • P. e. exustus Temminck in Temminck and Laugier de Chartrouse, 1825. Senegal, Gambia and Mauritania to Sudan, • P. e. floweri Nicoll, 1921. Endemic to the Nile Valley (Egypt). This subspecies was believed to be extinct until its recent rediscovery (Khil et al. 2012), • P. e. ellioti Bogdanov, 1881. SE Sudan E to Eritrea, N Ethiopia, Somalia. Includes somalicus Hartert, 1900 (Hartert 1909). SE South Sudan, SW Ethiopia, Kenya and N Tanzania. Includes emini (Reichenow in Heinroth 1919), • P. e. erlangeri (Neumann 1909 Specimens of Pterocles exustus were sent by Hemprich and Ehrenberg to Berlin in their shipments numbered 7, 8 and 10 (Lichtenstein 1823c(Lichtenstein , 1824(Lichtenstein , 1826. The 7 th shipment arrived in March 1823 and comprised 22 adult specimens listed as Pterocles senegalensis M.H.C. Lichtenstein, 1823 (a name later on found to be pre-occupied, see below) in the first inventory list of the shipment (Lichtenstein 1823b) as well as in the unpublished catalogue 1857. The only adult specimens from this shipment found nowadays in Berlin are ZMB 11417 and ZMB 11418. 17 specimens, most likely never seen by Temminck, were given to an auction in 1823 comprising two specimens that ends up to Tartu museum, one to the anatomical collection in Berlin (at this time different than the zoological collection that became the ZMB, this specimen could not be retrieved) and two to Feliks Paweł Jarocki at the Zoology Cabinet of Warsaw University (Lichtenstein 1823b). The whereabouts of the remaining specimens from this auction are unknown as the whereabouts of the three last specimens of this shipment. The 8 th shipment that arrived in Berlin in May 1824 comprised only five specimens, also listed as Pterocles senegalensis M.H.C. Lichtenstein, 1823; they were never incorporated the Berlin's collections and their whereabouts remain unknown. It is most likely that Temminck did not see these specimens. Finally, the 10 th shipment included a single specimen (ZMB 11416) and arrived in April 1826. It is impossible that this specimen formed part of Temminck's type series because his planches coloriées 354 (male) and 360 (female) were issued with livraisons 60 (23 July 1825) and 61 (27 August 1825), respectively (Dickinson 2001: 47).
ZMB also houses two other specimens (ZMB 11572 and ZMB 11606) from Beni Suef, Egypt (Hemprich and Ehrenberg [September 1820-1825]). These specimens were catalogued separately as Pterocles exustus in the catalogue 1857 and are not part of the type series as they are young birds ("pullus" is mentioned in Berlin's database) -Temminck described only the male and the female, but not the young.
There is another questionable specimen (ZMB 11419), a female collected (or traded) by "Verreaux" from Senegal. As it is not clear when it arrived in the collection, it cannot be decided whether it is a syntype or not. Having originated from Senegal, it belongs to the nominate subspecies. designated as "Probable syntype" by Gouraud (2015). Under current taxonomy, this specimen belongs to floweri.
The Forschunginstitut und Naturmuseum Senckenberg (formerly Senckenberg Museum Frankfurt am Main, hereafter SMF) houses two specimens: SMF 23454 (male) and SMF 23455 (female) from Egypt and from the Rüppell Collection. There are no more data except that SMF 23455 bears the date "1843". This is most likely a lapsus for 1834, as Rüppell was not in Africa in 1843. Indeed, the German explorer travelled four times in Africa: in 1817 (no collecting), in 1822-1827 and 1831-1834 (both trips providing important collections), and finally in 1849-1850 when only a handful of birds were collected (see Steinheimer 2005). SMF 23454 and 23455, most probably belonging to floweri, do not bear any original Rüppell's label, corroborating that they are not part of the type series (Gerald Mayr in litt. 31 July 2015, Frank Steinheimer in litt. 6 August 2015). Voisin et al. (2004) did not mention any type of this taxon in the Muséum National d'Histoire Naturelle of Paris. A search on the MNHN online database, so far comprising only the specimens kept in the Laboratoire but not those in the Zoothèque, indicated 51 specimens of the various subspecies Pterocles exustus. The oldest specimens are from Adolphe Boucard , therefore far too late to have been at Temminck's disposal. No type specimen is believed to be present in the Zoothèque (Claire Voisin in litt. 16 November 2015). It is unknown whether the Verreaux' specimen ZMB 11419 nowadays housed in Berlin is the specimen that Temminck saw in Paris.

The problem
Distributions of ellioti, olivascens, erlangeri and hindustan are well established and do not present any nomenclatural or taxonomical issues in respect to the nominate subspecies. However, the situation between floweri and exustus is problematic and necessitates a review. When describing his floweri, from Upper Egypt and Fayum, Nicoll (1921) originally named it Pterocles senegalensis floweri, well aware that Lichtenstein's senegalensis (Lichtenstein 1823a) ranged from Senegambia to Nubia (actual south Egypt and north Sudan). At the end of the 19 th century, Ogilvie-Grant (1893: 12) used already the name exustus Temminck instead of senegalensis Lichtenstein but the author did not give any reason. It was only a decade after Nicoll's description that Pterocles senegalensis M.H.C. Lichtenstein, 1823, was found to be pre-occupied by Tetrao senegalensis Shaw, 1810(Bannerman 1931: 290 footnote 1, see Dickinson et al. 2006: 343 for use of the date 1810 as well as the authorship), a junior synonym of Tetrao senegallus Linnaeus, 1771, and subsequently replaced by Pterocles exustus Temminck, 1825 (see e.g. Hartert 1912-1921: 1510, Bannerman 1931: 290, Hutson and Bannerman 1931, Mackworth-Praed and Grant 1937, Peters 1937. Hartert (1912Hartert ( -1921Hartert ( : 1510, Mackworth-Praed and Grant (1937) and Peters (1937: 4) restricted the range of nominate exustus to Senegal as follows: "Senegal, Ägypten, Nubien. Terra typica Senegal", "Senegal" and "West coast of Africa, Egypt and Nubia, = Senegal", respectively. More recently, in regards to floweri distribution, Gouraud (2015) pointed out that the type locality of exustus should be clarified and recommended lectotypification of a non-Egyptian specimen from the P. e. exustus series (Arts. 73.2.3 and 76.2 of the Code).