We illustrate Phrynus tessellatus in detail from northwestern Trinidad and present the first record of a population in South America. In addition, we describe the mating behaviour and spermatophore formation, which show no significant differences useful for taxonomic analysis within the genus, but among different genera and families. However, after deposition of the spermatophore on the substrate, the male modifies the anterior parts of the head with its chelicera. This behaviour differs markedly from related phrynid species. The purpose of this unexpected procedure is not clear and further research is necessary.