Polynoncus argentinus ( Harold, 1872 )

Costa-Silva, Vinícius, Strümpher, Werner P., Thyssen, Patricia J. & Vaz-de-Mello, Fernando Z., 2024, Taxonomic revision of the South American genus Polynoncus Burmeister, 1876 (Coleoptera: Scarabaeoidea: Trogidae), Journal of Natural History 58 (1 - 4), pp. 14-166 : 35-38

Polynoncus argentinus ( Harold, 1872) revalidated

( Figures 4g , 9–10 )

Trox argentinus Harold, 1872: 143 , 189 (original description); Preudhomme de Borre 1886: 69 (checklist); Bruch 1911: 193 (checklist); Arrow 1912: 53 (catalogue); Blackwelder 1944: 218 (checklist – as ‘ Argentina ’); Vaurie 1962: 120 (synonymised with T. gemmifer )

Trox (Polynoncus) argentinus : Scholtz 1982: 16 (catalogue – as a synonym of T. gemmifer )

Polynoncus argentinus : Pittino 1987: 384 (reinstated as a valid name); Scholtz 1990: 1430 (synonymised with T. gemmifer ); Zidek 2013: 7 (checklist); Zidek 2017: 98 (checklist, as synonym of T. gemmifer ); Smith 2017: 92 (as synonym of T. gemmifer ; records and comments)

Type specimens examined. LECTOTYPE, HERE DESIGNATED. (♂ MNHN – Figure 9 ) First label [white, aged]: ‘ Cordoba / Lorentz’. Second label [white, aged, Edgar von Harold’s handwriting]: ‘ Tr. argentinus / mihi typ’. Third label [white, aged, with black frame, typeset]: ‘Ex-Musaeo / E. Harold’. Fourth label [pink, typeset]: ‘Type’. Fifth label [white with green frame, handwritten]: ‘argentinus Har’. Sixth label [white, Patricia Vaurie’s handwriting]: ‘ Trox / gemmifer / Har. / Vaurie´61’. Seventh label [red with black frame, printed]: ‘ LECTOTYPE / Trox argentinus / Harold 1872 / des. V. Costa-Silva, 2022’. Eighth label [white with black frame, Vinícius Costa-Silva’s handwriting]: ‘ Polynoncus ♂ / argentinus / ( Harold 1872) / Det. V. Costa-Silva, 2022’ ( Figure 9e ). Type locality: ‘Córdoba’ ( Argentina), collected by Paul Günther Lorentz (1835–1881), a German botanist who lived in Córdoba, between 1870 and 1874 ( Lorentz 1875). According to the author, he arrived in Córdoba in October 1870 and spent several months collecting around the city. However, in November 1871, Paul Lorentz began an expedition away from Córdoba that finished in May 1872. Considering that P. argentinus was described in 1872, it is possible that the specimens examined by Harold were collected in 1870–1871 around Córdoba city (for more details, see Lorentz 1875, p. 94–96).

PARALECTOTYPE (1 ♂ MNHN) . First label [white, aged, handwritten]: ‘ Lorentz’ . Second label [white, aged, Edgar von Harold’s handwriting]: ‘ Trox / argentinus / typ. Harold’. Third label [yellow with black frame, Vinícius Costa-Silva’s handwriting] : ‘ PARALECTOTYPE ♂ / Trox argentinus / Harold 1872 / des. V. Costa-Silva, 2022’. Fourth label: ‘ Polynoncus ♂ / argentinus / ( Harold, 1872) / Det . V . Costa-Silva, 2022’.

Differential diagnosis. Polynoncus argentinus is morphologically similar to P. pseudogemmifer sp. n. However, the two species can be distinguished by the shape of the pronotal ridges and their distinct male genitalia. In P. argentinus , the pronotal ridges are complete, separated into two lines (on each side) in the middle forming a well-defined triangle with shallow fovea ( Figure 4g ). The ridges are similar in P. pseudogemmifer ; however, the internal line of the triangle is not complete (sometimes absent) ( Figure 4h ). The odd-numbered costae are also useful to separate the two species: in P. argentinus , the odd tubercles are more rounded and raised ( Figure 9a,b ), while in Polynoncus pseudogemmifer , the odd tubercles are generally flat and fewer in number (each tubercle always bigger than the diameter of scutellum; Figure 60a ).

The male genitalia of the two species are distinct as well: in lateral view, the median lobe of P. pseudogemmifer is constricted before the apex, while in P. argentinus the median lobe is parallel, without constriction ( Figure 9d ) (for more details, see Pittino 1987, p. 384).

Geographic distribution. Polynoncus argentinus has been recorded in the semiarid regions of Argentina ( Figure 10 ). Here we present the first records of this species from Uruguay, and Brazil. The Uruguay records are based on one male specimen housed in MCZ without further information on the specific locality. Similarly, a single male specimen found in BMNH, with an old handwritten label reading ‘Brazil’, corresponds to P. argentinus . Considering the distribution of P. argentinus , it would not be surprising to find the distribution of this species extending across Uruguay and into southern Brazil, but additional sampling is needed in the region to delineate its distribution boundaries and to confirm the presence of P. argentinus in both countries.

Examined non-type material (130 specimens). ARGENTINA: Buenos Aires, Bahía Blanca, no date or collector (1♂ and 1♀ MACN) ; Bahia Blanca , no date, C. Darwin [Beagle voyage] leg. (2♂ and 1♀ BMNH) ; Bahía San Blas, February 1932, no collector (1♂ MLPA) ; Bahía San Blas , no date or collector (1♂ and 1♀ MACN) ; Bajo Hondo, no date or collector (1 CEMT) ; Balcarce, no date, J.M. Gallardo leg. (1♂ MACN) ; Coronel Suárez, Sierra de Cura Malal , 5 March 1925, P. Saggero leg. (1♀ MLPA) ; Gorchs , December 1916, G. Pallermo leg. (1♀ MACN) ; Los Cardales, 18 January 1942, no collector (2♂ and 1 unsexed BMNH) ; Medanos , 11 November 1946, Willink leg. (2 IFML) ; Medanos , November 1946, Willink leg. (1 IFML) ; Puán, Felipe Solá , February 1961, A. Martinez leg. (6 MZSP) ; Puán, Felipe Solá , November 1961, A. Martinez leg. (2♂ and 19 unsexed MZSP) ; Puán, Estancia Barrau, 30 km south-west of the Villa Iris Station , November 1946, Coll. Martínez (1 CMNC) ; Tres Arroyos , 30 January 1938, M. Biroben and Scott leg. (1♂ MLPA) ; Villarino Playa La Chiquita , 27 March 2014, under dead penguin, G. Flores and N. Zanetti leg. (2 IADIZA) ; without specific locality, date or collector (1♂ and 3♀ MLPA). Catamarca, Campo del Pucará , 9 January 1951, no collector (3♂, 1♀ and 1 unsexed IFML) ; Cerro El Manchao, 3000 m, 16–20 January 1959, R. Golbach leg. (1 IFML). Chubut , without specific locality, date or collector (1♂ MACN). Córdoba, Río Cuarto, Estación Monte de los Gauchos , 23 February 1996, Maceda leg. (1♂ and 1 unsexed IADIZA) ; without specific locality, October 1942, no collector (1♀ BMNH). La Pampa, Bajo Giuliani , 3 March 1999, halophilic material, Gouts, Rastelli leg. (1 IADIZA) ; Catriló , 24 February 1938, M. Biroben and Scott leg. (5♂ and 2♀ MLPA) ; Catriló , 24 March 1938, Biraben leg. (3♂ MLPA) ; Catriló ,no date or collector (1♀ MACN) ; Cuchillo Có,1913,A. Copello leg. (1♀ MACN) ; Cuchillo Có, no date or collector (1♀ MACN) ; Santa Rosa , 26 April 1997, Bárbara Corró Molas leg. (1♀ IADIZA) ; Santa Rosa, Faculdad de Agronomia , 25 April 1995, Bárbara Corró Molas leg. (1♂ IADIZA) ; Santa Rosa, Parque Industrial 15 June 1997, Bárbara Corró Molas leg. (1♂ IADIZA) ; Santa Rosa, Parque Industrial 2 May 1997, Bárbara Corró Molas leg. (1♂ IADIZA) ; Toay, Parque Luro Provincial Reserve , November 2003, Pessino leg. (1♀ IADIZA). La Rioja , without specific locality or date,A. Breyer leg. (1♀ MACN). Misiones , without specific locality or date, A. Breyer leg. (1♀ MACN). Neuquén , without specific locality, 1907, Dr Adolf Lendl leg. (3♂ and 3♀ MNHN). Río Negro, Lamarque , 5 November 1963, M. Fritz leg. (1♂ CVMD) ; Río Colorado , 13–19 November 1946, H. and W. leg. (2 IFML) ; Río Colorado , 14–19 November 1946, Hayward and Willink leg. (4 IFML) ; Rio Colorado , 29 February 1941, M. Biroben leg. (1♂ MLPA) ; Rio Colorado , no date or collector (1 CEMT) ; without specific locality, date or collector (1 MACN) ; without specific locality or date, A. Breyer leg. (1♀ MACN). San Luis , 18 km S. Arizona , 250 m, 18–23 January 1982, H. and A. Howden leg. (1♂ and 10 unsexed CMNC) ; Arizona , February 1980, M. Viana leg. (2♂ and 2♀ CVMD) ; Bajo Hondo , no date or collector (3♂ MLPA) ; without specific locality, 21 December 1925, no collector (1♀ MACN) ; without specific locality, date or collector (1♂ and 2♀ MLPA). Tucumán , without specific locality, date or collector (1♀ MNHN). Without specific locality, ‘ Buenos Aires a Corrientes’ [going up the Paraná River], 15 February–15 March 1827, d’Orbigny leg. (1♀ MNHN). BRAZIL [dubious locality]: without specific locality, date or collector (1♂ BMNH). URUGUAY: Montevideo, without specific locality, date or collector (1♂ MZLU; 1♀ MCZ).

Remarks. The name Polynoncus argentinus has had an unstable taxonomic history. It was originally described by Harold (1872) in the genus Trox , later synonymised with Polynoncus gemmifer ( Blanchard 1847) by Vaurie (1962),and reinstated as a valid name by Pittino(1987), to be again treated as a synonym of P. gemmifer by Scholtz (1990). However,careful examination of the type specimens of both species confirmed these two species are indeed distinct.

Polynoncus argentinus can easily be separated from P. gemmifer by the absence of setae on the surface of hypomeron (setose in P. gemmifer ); pronotum with antero-lateral tubercle indistinct, covered by tomentosity (distinct and shiny in P. gemmifer ); apex of median lobe laterally flattened and lateral margins parallel in dorsal view (apex rhomboidal with lateral margins diverging forward in P. gemmifer ). Consequently, P. argentinus is removed from synonymy with P. gemmifer , and reinstated as a separate valid species.

Figures

Figure 4. Differential morphology in Polynoncus spp.: a, without humeral callus [P. hemisphaericus]; b, with humeral callus [P. longitarsis]. Apex of mesotibia c, with tooth [P. peruanus] and d, without tooth (white arrow) [P. crypticus]. Posterior margin of clypeus e, emarginate [P. bullatus] and f, truncate (white arrow) [P. hemisphaericus]; pronotal ridges of pronotum in g, Polynoncus argentinus and h, Polynoncus pseudogemmifer sp. n. (paratype). Scale bar: 1 mm.

Figure 9. Lectotype of Trox argentinus Harold, 1872 (now Polynoncus argentinus) here designated: habitus in a, dorsal and b, lateral view. Male genitalia in c, dorsal and d, lateral view; e, labels. Scale bar: 1 mm.

Figure 10. Distribution map of Polynoncus argentinus (red circles), P. bifurcatus (green triangles), and P. chilensis (blue squares) in South America. The records with a black dot in the centre indicate the type locality of the respective species.

Figure 60. Holotype of Polynoncus pseudogemmifer sp. n.: habitus in a, dorsal, b, ventral and c, lateral view; male genitalia in d, dorsal and e, lateral view; f, labels. Scale bar: 1 mm.