Polynoncus mirabilis Pittino, 1987

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 : 105-109

Polynoncus mirabilis Pittino, 1987

( Figures 5I , 44–46 )

Polynoncus mirabilis Pittino, 1987: 391 (original description); Scholtz 1990: 1453 (redescription); Diéguez 2008: 20 (redescription and records from Chile); Gómez 2008: 516 (key to Argentinean species); Zidek 2013: 13 (checklist); Zidek 2017: 104 (checklist); Smith 2017: 97 (distribution data and comments); Costa-Silva and Diéguez 2020:272 (records from Argentina); Mondaca 2023: 210 (checklist from Chile).

Type specimen examined (through detailed photographs). HOLOTYPE. (♂ RPMI – Figure 44 ) First label [light brown with black border, Gustave Baer’s handwriting]: ‘Santiago / Peron’. Second label [light brown, typeset]: ‘Baer’. Third label [white, typeset]: ‘EX COLL. / WINKLER, WIEN’. Fourth label [red with black border]: “ Polynoncus / mirabilis n. sp. / HOLOTYPUS ♂ / det. Pittino [typeset] 1987. Fifth label [white, handwritten]: ‘COLL. / R. PITTINO’ ( Figure 44e ). Type locality: ‘Santiago, Perón’ [Santiago de Chuco, Peru (probably mislabelled)]. According to the original labels on the holotype, the type specimen was collected by the French naturalist Gustave Adolphe Baer (1839–1918), probably on his trip to South America between 1896 and 1906 ( Bear 1907; Chopard 1918; Lamas 1980; Horn et al. 1990a; Cambefort 2006). In his description, Pittino (1987, p. 391) mentions ‘Santiago, Peron’ as the type locality, without further information. In a search for other type specimens collected by Baer in South America, we found housed in MNHN the type of Pilobalia baerii Fairmaire, 1902 ( Coleoptera : Tenebrionidae – Figure 45a ), which has identical labels to those on the type of P. mirabilis ( Figure 45b ). However, the locality name on the original labels on the tenebrionid type clearly reads ‘Santiago Pérou’ and not ‘Santiago Peron’ as interpreted by Pittino (1987) when he described P. mirabilis . According to Fairmaire’s description (1902, p. 149), the locality written on the label of the type of P. baerii refers to Santiago de Chuco (La Libertad, Peru).

According to Solier (1851) and Blanchard (1851), many other naturalists misinterpreted the insects collected in Peru and Chile (also see Smith 2002). It is likely that the specimen of P. mirabilis was mislabelled by Baer, since the most boreal record known for the species is Bío-Bío (VIII Chilean region), and its distribution to Peru (= Pérou, in French) is improbable.

Differential diagnosis. Polynoncus mirabilis is morphologically similar to P. chilensis and P. longitarsis . It can be distinguished from the latter by having tubercles no more than 2 times longer than wide (which is 3–4 times longer than wide in P. longitarsis ) in the third elytral costae and by tubercles with shiny surface or with half of surface covered by discreet velutinous area ( P. longitarsis have the odd-numbered elytral costal tubercles completely shiny).

Polynoncus mirabilis is more similar to P. chilensis , and the two species have frequently been confused in collections. However, the shape of the humeral callus can be useful to separate the two species: in P. mirabilis , the humeral callus is less prominent (one is able to see the lateral margin of elytra in dorsal view ( Figure 5i ), while it is very prominent in P. chilensis , covering the lateral margin of elytra in dorsal view ( Figure 5h ). For description, diagnosis and detailed illustrations of male genitalia, see Pittino (1987, p. 391). Also see Scholtz (1990, p. 1453) and Diéguez (2008, p. 20) for additional morphological comments.

Geographic distribution. Polynoncus mirabilis occurs in the arid zones of southern Chile and Argentine Patagonia ( Figure 46 ), and is sympatric with the morphologically similar species P. chilensis and P. longitarsis . The records plotted on the map ( Figure 46 ) match those presented by Diéguez (2008), Smith (2017), Costa-Silva and Diéguez (2020), and Mondaca (2023). Scholtz (1990) presented a map with a record of P. mirabilis from the north of Argentina without any information about the origin of the specimen examined. Based on our study, this record needs to be treated with caution until new and additional data or specimens are forthcoming from this region.

Examined non-type material (40 specimens). ARGENTINA: Chubut, Valle del Lago Blanco, 1903, no collector (3 BMNH) ; without specific locality, ‘ Patagonia’ , no date or collector (1♂ and 11 unsexed BMNH) ; without specific locality, ‘ Patagonia’, no date or collector (1♂, 4♀ and 2 unsexed MNHN). Neuquén, 32 km E of Paso Hua-Hum, Lago Lacar , 950 m, 40.133°S, 71.433°W, 11 January 1988, human dung, Ashworth, Fugiseth, Maliscke leg. (1♂ CEMT) ; 32 km E of Paso Hua-Hum, Lago Lacar , 950 m, 40.133°S, 71.433°W, 23 December 1987, human dung, Ashworth, Fugiseth, Maliscke leg. (1♀ CEMT). CHILE: Araucanía (IX Region), Curacautin, Cuesta Las Raíces , February 2001, Alfredo Ugarte leg. (1 CVMD) ; Curacautin, Cuesta Las Raíces , December 1999, Alfredo Ugarte leg. (1♂ CVMD) ; Malalcahuelo , January 2000, A. Ugarte leg. (2♂ CVMD) ; Malleco, Malalcahuello , January 1998, A. Ugarte leg. (1 JZPC) ; Malleco, Nahuelbuta National Park , 1000 m, February 2000, Guido Castillo leg. (1♂ CVMD) ; Malleco, Nahuelbuta National Park, 1400 m, 9 December 1984 – 16 February 1985, Nothophagus - Araucaria forest , S. and J. Peck leg. (1♂ and 2 unsexed BMNH). Aysén (XI Region), Coyhaique, January–February 1999, no collector (1 BMNH) ; Coyhaique, Balmaceda , 3 km N, 45.866°S, 71.683°W, 22 November 2011, Maurício Chang leg. (1♂ CVMD). Bío-Bío (VIII Region), Alto Cayucupil, Cordillera de Nahuelbuta , 3–9 March 1997, Danilo Escobar leg. (1 CVMD) ; Chillian , 1200 m, 36.866°S, 71.650°W, 30 November 1990, ground traps in forest, Endrödy-Younga leg. (2 TMSA). Los Lagos (X Region), Correntoso , Fundo El Mirador, 30 March 2006, V.M. Diéguez leg. (1♂ CVMD). Los Ríos (XIV Region), Valdivia , 10–12 January 1980, E. Krahmer leg. (1 MNNC).

Figures

Figure 5. Differential morphology in Polynoncus spp.:lateral margin of pronotum a, bulbous [P.vazdemelloi] and b, rounded [P.gemmingeri]; pronotal ridges and basal tubercles of pronotum c, fused [P.furcillifer] and d, separated (black line) [P.parafurcatus]; surface of elytra e, with tubercles [P.pedestris] and f, without tubercles [P. diffluens]; g, pronotal ridge and antero-lateral tubercle connected by (white arrow) [P. patagonicus]; h, humeral callus prominent (white arrow) in P. chilensis and i, humeral callus not prominent (white arrow) in P. mirabilis. Scale bar: 1 mm.

Figure 44. Holotype of Polynoncus mirabilis Pittino, 1987: habitus in a, dorsal and b, lateral view; male genitalia in c, dorsal and d, lateral view; e, labels. Photos by Alberto Ballerio. Length of specimen: 16.3 mm.

Figure 45. Type labels of a, Pilobalia baerii Fairmaire, 1902 (Tenebrionidae) and b, Polynoncus mirabilis Pittino 1987, both species collected by Gustave Adolphe Baer between 1896 and 1906. Photos copyright MNHN (available in https://science.mnhn.fr/institution/mnhn/collection/ec/item/ec9536? listIndex=1&listCount=7) and Riccardo Pittino, respectively.

Figure 46. Distribution map of Polynoncus mirabilis (red circles), P. parafurcatus (green triangles), and P. patagonicus (blue squares). The records with a black dot in the centre indicate the type locality of the respective species.? = dubious record.