The taxonomy of Pterocladiella from Pacific South America remains less studied. On the basis of morphological observations and mitochondrial cox1 and plastid rbcL sequences, we describe a new species, P. andresii, from Chile and characterize recently collected specimens of P. caloglossoides from Peru, the first verified since Howe’s original collections of the type. Pterocladiella andresii is distinguished by small turfs of simple, narrow, compressed thalli that are rarely irregularly branched, and possess rhizines in the medulla, tetrasporangial sori with sterile a margin, and v-shaped to irregularly arranged tetrasporangia. New collections of Pterocladiella caloglossoides from northern Peru accord well with its original description. Both cox1 and rbcL phylogenies revealed that P. andresii was sister to P. caloglossoides from Peru, and this group formed a clade with P. luxurians from California, USA. Morphological differences among P. andresii and its putative relatives are presented.