Phalloceros enneaktinos Lucinda, 2008

Souto-Santos, Igor Cavalcanti de Araújo, Ferraro, Gustavo Andrés, Jennings, William Bryan, Vergara, Gabriela Lucia da Silva & Buckup, Paulo Andreas, 2019, Geographic distribution of Phalloceros Eigenmann, 1907 (Cyprinodontiformes, Poeciliidae) in the Ilha Grande Bay Hydrographic Region, Rio de Janeiro, Brazil, Check List 15 (1), pp. 181-192 : 187-188

Phalloceros enneaktinos Lucinda, 2008

Figure 2C

Materials examined. Brazil: Rio de Janeiro: Área alagada na restinga da praia de Lopes Mendes, abastecida por um riacho, Ilha Grande, município de Angra dos Reis (23°10ʹ13ʺ S, 044°07ʹ24ʺ W), R.M. Dias, N. Nagatani, 9 November 2014 ( MNRJ 42910). Charco na trilha de Mamanguá, município de Parati (23° 18ʹ43ʺ S, 044°39ʹ05ʺ W), M. R.S. Melo, P.A. Buckup, 21 April 2000 ( MNRJ 20250). Córrego da Toca do Boi, próximo ao portão de guarda do condomínio Laranjeiras, município de Parati (23°19ʹ44ʺ S, 044°40ʹ52ʺ W), M. R.S. Melo, P.A. Buckup, 23 April 2000 ( MNRJ 20252). Córrego da Toca do Boi, próximo a ponte a montante do condomínio Laranjeiras, município de Parati (23°19ʹ44.8ʺ S, 044°40ʹ54.6ʺ W), P.A. Buckup, D.F. Moraes Jr, I.C.A. Souto-Santos, M.M. Gonzalez, D. R.S. Peixoto, J. R. Amaral, 10 October 2014 ( MNRJ 43245). Córrego da Toca do Boi, próximo ao portão do condomínio Laranjeiras, município de Parati, no collector data, 3 March 1989 ( MNRJ 14847, paratypes; MNRJ 23609, holotype).

Identification. Phalloceros enneaktinos is morphologically very similar to P. harpagos . According to Lucinda (2008), P. enneaktinos differs from P. harpagos by having only 9 dorsal fin rays, but the number of rays is vari- able in the latter, ranging from 7 to 9. Our survey in the IGBHR of dorsal fin-ray counts among populations of these taxa confirmed the existence of overlapping fin-ray counts ( Table 3).

To further evaluate the distinction between these taxa, we compared COI sequences of individuals from the type locality of P. enneaktinos with samples of P. harpagos from other mainland rivers. Our DNA-sequence comparisons confirmed that the 2 species are genetically distinct ( Fig. 4), with a genetic divergence that exceeds accepted levels of intraspecific divergence in fishes (Hebert el al. 2003a, 2003b, Pereira et al. 2013). The Refined Single Linkage Analysis ( Ratnasingham and Hebert 2013) performed by the BOLD Systems algorithm assigned the 2 species to distinct Barcode Index Numbers ( BIN). Specimens of P. enneaktinos were assigned to BIN ACC028, and specimens of P. harpagos were assigned to BIN ADM 9037. These genetic data also confirmed the unreli- able nature of dorsal fin-ray counts as a diagnostic char- acter, because the sample from the Lopes Mendes beach on Ilha Grande island is conspecific with P. enneaktinos in spite of these specimens having a modal count of 8 dorsal fin rays. Unfortunately, variation in dorsal fin-ray counts renders the unambiguous identification of samples of P. enneaktinos from localities situated far from its type locality very difficult without molecular data.

Distribution. Phalloceros enneaktinos was previously known only from the rio Toca do Boi, a small coastal drainage, which flows directly into the Atlantic Ocean outside of Ilha Grande Bay ( Lucinda 2008). Here we record the presence of this species in a small stream that flows into the Saco do Mamanguá inlet, which is located inside Ilha Grande Bay, and in a wet area behind Lopes Mendes beach, which is on the southeastern portion of Ilha Grande ( Fig. 1).