Prionus (Antennalia) Casey, 1912

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 : 10-11

On Prionus (Antennalia) Casey, 1912

Casey (1912) defined Prionus (Antennalia) : “This group is given subgeneric rank, not solely because of the large and very complex, closely imbricated male antennae, which could very well be considered a simple development of the preceding types, but because of the distinctly different structure of the female antennae, the outer joints being transverse and bilaterally symmetrical. There seems to be but one species, though several forms represented in my collection by the female alone, which may be held to be subspecific for the present though possibly of higher value, are appended. The preceding group is characterized in one way by the relative scarcity of the females, while here this condition is reversed, the male being apparently much rarer than the female, denoting perhaps a difference in life habits of the two groups.”; and “In this group the eyes seem to be much more widely separated in the female than in the male, a feature not particularly evident in the other groups.” One more time, the subgenus was defined mainly based on the antennae. Casey (1912) was correct when he suggested that the antennae in males of Prionus fissicornis Haldeman, 1846 could be considered a simple development of preceding types [ Prionus (Riponus) = Prionus (Neopolyarthron) ]. Regarding the differences pointed out by Casey on the female antennae (i.e., “the outer joints being transverse and bilaterally symmetrical”), this does not make sense. Apparently, Casey (1912) was talking about the distal portion of antennomeres that are wide, projected and similar on both sides (outer and inner side). This is just a specific feature, and it is not very different from the antennae in females of some other species of Prionus mainly on distal antennomeres, as for example in P. imbricornis . As to the distance between upper eye lobes, it is not as wide as suggested by Casey (1912). In fact, the distance between upper eye lobes is somewhat variable in the species of Prionus (males and females).

Linsley (1962) and Chemsak (1996) redefined the group: “Antennae 25- to 30 segmented, poriferous system striolate; posterior tarsi with posterior lobes without spine at apex.” This description encompasses two mistakes. First, the antennae in females of P. fissicornis may have less than 25 segments. For example, Casey (1912) affirmed that the antennae in females of P. fissicornis have 23- to 24 joints; Casey (1912) described the holotype female of P. (Antennalia) fissicornis parviceps having antennae with 22 segments [this subspecies was synonymized by Linsley (1957)]; Casey (1912) described the holotype female of P. (Antennalia) fissicornis transversus as having antennae with 20 segments [this subspecies was synonymized by Linsley (1957)]; and Casey (1924) described the holotype female of P. (Antennalia) thoracicus as having antennae with 20 segments [this species was synonymized by Linsley (1947)]. The second problem is the tarsal shape. The apex of the metatarsomere III is, at least in some specimens, very distinctly spinose.

Once again, the only difference between Prionus (Neopolyarthron) and Prionus (Antennalia) would be the number of antennal segments (metatarsal shape variable in the former). As seen in Prionus (Neopolyarthron) , the number of antennal segments is not sufficient for differentiating among subgenera in Prionus . Also, the holotypes of P. (Antennalia) fissicornis transversus and P. (A.) thoracicus have antennae 20-segmented. Thus, the number of antennal segments in Prionus (Neopolyarthron) and P. ( Antennalia ) may be the same (20 segments).

Based on these considerations, it is not possible to separate Prionus (Antennalia) from Prionus (Neopolyarthron) , and thus, also from Prionus (Prionus) .