Prionus (Neopolyarthron) Semenov, 1899

Santos-Silva, Antonio, Nearns, Eugenio H. & Swift, Ian P., 2016, Revision of the American species of the genus Prionus Geoffroy, 1762 (Coleoptera, Cerambycidae, Prioninae, Prionini), Zootaxa 4134 (1), pp. 1-103 : 10

On Prionus (Neopolyarthron) Semenov, 1899

As seen above, Semenov (1899) erected Prionus (Neopolyarthron) based on a single feature: the number of antennal segments. In addition, according to him, the “appendages” of antennal joints are articulated. This is not true as the projections of antennomeres are not independently articulated from the antennal segment.

According to Linsley (1962), Prionus (Neopolyarthron) is characterized by: “Antennae 15- to 20 segmented, poriferous system striolate; posterior tarsi with posterior lobes of third segment without spine at apex, metasternum of male densely pubescent, of female glabrous.” Chemsak (1996) followed the same description.

However, the description of metatarsomere III is true (partially) only for species from USA. In Mexican species, currently placed in Prionus (Neopolyarthron) , at least P. (N.) aztecus has metatarsomere III with a very distinct spine at apex. This feature, tarsal shape, also is highly variable among the species of Prionus . Thus, it cannot be used as a generic or subgeneric differentiation, because it is not constant in Prionus (Neopolyarthron) or Prionus (Prionus) . For example, in Prionus (Prionus) mexicanus Bates, 1884 , the projection or spine at apex of metatarsomere III is slightly distinct.

The other character used by Linsley (1962) and Chemsak (1996), pubescence of metasternum, also is not a good feature to separate Prionus (Neopolyarthron) from Prionus (Prionus) . For example, Linsley (1962) wrote on Prionus (Prionus) laticollis ( Drury, 1773) : on male—“metasternum densely pubescent”; on female— “metasternum glabrous”. Thus, as the character also occurs in species of other subgenera, it cannot be used as distinctive. It cannot be used even if combined with the tarsal shape, because this combination (metasternum pubescent in males and glabrous in females, and metatarsomere III not spinose) also occurs in species of Prionus (Prionus) .

Now, using Linsley’s concept of Prionus (Neopolyarthron) , we have a single character to separate it from Prionus (Prionus) : the number of antennal segments. However, here we have more inconsistencies. According to Linsley (1962) and Chemsak (1996), Prionus (Prionus) have antennae with 12 or 13 segments, but in P. (P.) mexicanus , for example, the antennae have 14 segments. Thus, only one more antennomere would separate the two subgenera [at least 15 in P. ( Neopolyarthron ); at most 14 in P. ( Prionus )].We believe that this is arbitrary and insufficient to separate two subgenera. Although Linsley (1962) and Chemsak (1996) did not comment on the shape of the projection of antennomeres in males, they are highly variable in the species of Prionus . It can be wide, from slightly emarginated to distinctly bilobed, to moderately narrow and not emarginate. Thus, the projection of antennomeres in P. ( Neopolyarthron ) is similar to many species of P. ( Prionus ).

As all characters used to separate Prionus (Neopolyarthron) from Prionus (Prionus) are useless, and there are no other differential character (including the general appearance), we propose the former as a junior synonym of the latter.