Plistonax difficilis (Melzer, 1934)

Plistonax difficilis (Melzer, 1934) View in CoL

( Fig. 48 View FIGURES 43–50 )

Idiomerus difficilis Melzer, 1934b: 98 View in CoL .

Melzerus difficilis View in CoL ; Monné, 2005b: 179 View Cited Treatment (cat.; comb. nov.).

Plistonax difficilis View in CoL ; Silva Júnior et al., 2021: 510 (comb. nov.).

Remarks. This species was described based on specimens from Brazil ( São Paulo, Goiás, and Minas Gerais) and Argentina ( Tucumán). Currently, it is known from Peru, Bolivia ( Beni and Santa Cruz), Brazil ( Rondônia, Mato Grosso, Goiás, Minas Gerais, São Paulo, Paraná, and Rio Grande do Sul), Paraguay, and Argentina ( Tucumán and Formosa) ( Bezark 2024, Monné 2024b, Tavakilian & Chevillotte 2023). Monné (2005b) provided a new name for Idiomerus Melzer, 1934 due to homonymy with Idiomerus Imms, 1912 .

According to Silva Júnior et al. (2021) on P. difficilis : “Femora with one yellow stain on inner surface of globose region (only males).” However, it was not informed, and was not used in the analysis that the males have a deep depression on the ventral surface of all femoral clubs with dense setae, and not a yellow stain as reported. This feature is absent in all other species of Plistonax Thomson, 1864 . We believe that the synonym of Melzerus with Plistonax was a mistake. However, we prefer not to reinstate the genus here.

Material examined. BRAZIL, Mato Grosso do Sul ( new state record): Campo Grande , CNPGC [Centro Nacional de Pesquisas de Gado de Corte—EMBRAPA], 1 specimen (MNRJ-ENT-47627), 28.X.1976, W.W. Koller leg. ( MNRJ) .