A possible phylogenetic signal in milliped chemical defenses: The polydesmidan milliped Leonardesmus injucundus Shelley & Shear secretes p-cresol and lacks a cyanogenic defense (Diplopoda, Polydesmida, Nearctodesmidae)

The nearctodesmid polydesmidan milliped Leonardesmus injucundus Shelley and Shear was found to secrete p-cresol as a defensive fluid, and to lack mandelonitrile, benzaldehyde and hydrogen cyanide, heretofore found to be characteristic of most polydesmidan millipeds. The sympatric nearctodesmid Kepolydesmus anderisus Chamberlin does not secrete p-cresol, but utilizes the usual cyanogenic pathway. These are only the second reports on defensive secretions in the milliped family Nearctodesmidae. p-Cresol may be the characteristic secretion of members of the nematophoran order Callipodida (p-cresol is reported here from Delophon georgianum Chamberlin [Callipodida, Abacionidae] for the first time) and thus its presence in a polydesmidan may be indicative of a relationship between Callipodida and Polydesmida, which orders share other synapomorphies. Examples of two species of Glomeridesmus (Glomeridesmida, Glomeridesmidae) were examined and found to lack any sign of repugnatorial pores.