Description and ecology of new Pijnackeria stick insects: four bisexual species and a triploid parthenogen with their phyletic relationships


Corresponding author: Valerio Scali (


Recently, the Iberian stick insect genus Pijnackeria has been erected by splitting Leptynia Pantel on the basis of several distinguishing features. In addition to Pijnackeria hispanica, the tetraploid all-female type species, molecular, karyological and SEM investigations led to the recognition of four bisexual and one triploid unisexual new species. Bisexuals' karyotypes (2n = 37/38) differ for minute traits and the haploid set is repeated, with few differences, three or four times in the polyploids that appeared to be of hybrid origin. Diagnostic morphological traits were found among body size parameters, antennal articles, male cerci, ovipositor valve and egg chorionic features. All species commonly feed on the broom Sarothamnus scoparius, but habitat disturbance appeared to induce food plant shifts. Moreover, trends from bisexuality to unisexuality through spanandry, probably related to habitat disruption, have been witnessed. The diploid species (Pijnackeria lucianae, Pijnackeria barbarae, Pijnackeria lelongi and Pijnackeria originis) have small ranges, while the polyploid hybrids (Pijnackeria masettii and P. hispanica) spread through Spain and Southern France, featuring a clear geographic parthenogenesis scenario, by colonizing wide areas and likely displacing their ancestors, or even leading them to extinction. Cyclic climatic changes and natural or anthropic habitat fragmentation may have been also of relevance in shaping present-day distribution.