Brazilian livebearer expert Paulo Lucinda has described 21 new species of the South American livebearer genus Phalloceros in a study published in a recent issue of the journal Neotropical Ichthyology.
Phalloceros is a livebearer genus found in the southern and southeastern rivers of South America, and is previously considered to consist of only one species, P. caudimaculatus.
The twenty-one new species are distinguished from P. caudimaculatus and each other by a combination of osteological (bone) characters, the shapes of the gonopodia, colour pattern, fin-ray counts and some relative proportions of body parts.
The 21 new species described in the study are: P. alessandrae, P. anisophallos, P. aspilos, P. buckupi, P. elachistos, P. enneaktinos, P. harpagos, P. heptaktinos, P. leptokeras, P. leticiae, P. lucenorum, P. malabarbai, P. megapolos, P. mikrommatos, P. ocellatus, P. pellos, P. reisi, P. spiloura, P. titthos, P. tupinamba, and P. uai.
These species have been identified as new in a previous study of the phylogeny of the genus published by Paulo Lucinda and Roberto Reis in 2005.
For more information, see the paper: Lucinda, PHF (2008) Systematics and biogeography of the genus Phalloceros Eigenmann, 1907 (Cyprinodontiformes: Poeciliidae: Poeciliinae), with the description of twenty-one new species. Neotropical Ichthyology 6, pp. 113"158.