Polynoncus gordoni ( Steiner, 1981 )

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 : 97-98

Polynoncus gordoni ( Steiner, 1981)

( Figures 37 , 39 )

Trox gordoni Steiner, 1981: 205 (original description)

Polynoncus gordoni : Scholtz 1986a: 362 (systematics); Scholtz 1990: 1446 (redescription); Zidek 2013: 10 (checklist); Ratcliffe et al. 2015: 189 (checklist from Peru); Zidek 2017: 101 (checklist)

Type specimens examined (through detailed photographs). HOLOTYPE. (♂ USNM – Figure 39 ) First label [white, typeset]: ‘ PERU: Cuzco / 15 km SW / Limatambo / 25 February 1979 / W. E. Steiner’. Second label [red, typeset] : ‘ HOLOTYPE ♂ / Trox gordoni [underlined] / W. E. Steiner / USNM # 76505’. Third label [white, typeset]: ‘USNMENT / [QR Code] / 01476214’ ( Figure 39c ). Type locality: ‘Limatambo, Cuzco’ (Peru), collected by Warren E. Steiner.

ALLOTYPE (♀ USNM). First label [white, typeset]: ‘ PERU: Cuzco / 15 km SW / Limatambo / 25 February 1979 / W. E. Steiner’. Second label [red, typeset] : ‘ ALLOTYPE ♀ / Trox gordoni [underlined] / W.E. Steiner / USNM # 76505’. Third label [white, typeset]: ‘USNMENT / [QR Code] / 01476213’.

Differential diagnosis. This rare species is most similar to P. sallei and P. gemmingeri . Polynoncus gordoni differs from P. gemmingeri by having the pronotal ridges connecting the basal tubercle, which are distinctly separate in the latter. Also, Polynoncus gordoni have the elytral tubercles elongate, which is rounded in P. gemmingeri . The male genitalia of the two species are very similar (for a more detailed discussion of the male genitalia of this group of closely related species, see Steiner (1981, p. 209).

Lastly, Polynoncus gordoni is also similar to P. sallei but can be separated from the latter by the shape of the clypeal margin, which is emarginate in P. gordoni and truncate in P. sallei . Furthermore, in Polynoncus sallei the elytral tubercles (mainly on the odd-numbered costae) are usually rounded and more numerous across the length of the elytra (more than eight), as opposed to P. gordoni which has the tubercles elongate and less numerous (fewer than eight).

Geographic distribution. Polynoncus gordoni was previously only known from the type locality. We examined two specimens from northern Peru, a substantial range expansion northward from where it was previously known. Polynoncus gordoni appears to be restricted to the Andean Mountain range in Peru ( Figure 37 ).

Examined non-type material (4 specimens). PERU: Amazonas, Bagua, Achaguay Alto , 688 m, 5.590°S, 78.503°W, 31 March 2012, January Medina and J . Grados leg . (1♂ CEMT); Bagua, Achaguay Alto , 688 m, 5.590°S, 78.503°W, 31 March 2012, I . Medina and J . Grados leg . (1 CVMD); Chachapoyas , 1889, M . de Mathan leg . (1♀ MNHN) . Ayacucho, near to Ayacucho, Wari ( Huanta ), 2500 m, 20 March 1995, Pedro Hocking leg . (1♂ MUSM) .

Figures

Figure 37. Distribution map of Polynoncus gemmingeri (red circles), P. gordoni (green triangles), and P. hemisphaericus (blue squares) in South America. The records with a black dot in the centre indicate the type locality of the respective species.

Figure 39. Holotype of Trox gordoni Steiner, 1981 (now Polynoncus gordoni): habitus in a, dorsal and b, lateral view; c, labels. Photos by Karolyn Darrow (USNM).