Helicops apiaka

According to the information given in Kawashita-Ribeiro et al. (2013), H. apiaka can be distinguished from all its congeners, except H. angulatus by the following combination of characteristics: absent intergenials, subcaudal keels present and 21–22 dorsal scale rows at mid-body (compared to 19 in H. gomesi). From H. angulatus, it differs by having 21–24 dorsal scale rows at anterior body, 21–22 at mid-body and 17–19 at posterior body (versus 19–21/19–20/17–19 in H. angulatus) and by having 118–127 ventral scales in males and 124–132 in females (versus 105–123 in male and 109–123 in female H. angulatus), as well as hemipenes morphology. The specimens examined in Kawashita-Ribeiro et al. (2013) originated from neighbouring areas to the H. apiaka locations. Our own examinations revealed that males of H. angulatus possess 103–119 ventrals in males and 104–125 in females. There is considerable overlap, especially between female specimens of the two species, thus excluding this character for identification. Besides that, we detected two specimens displaying morphology characters of H. angulatus (colouration, subcaudal keels, remaining pholidosis), but showing considerably more ventrals than other specimens of H. angulatus (SMF 17819, a female, with 156 ventrals and ZSM 0595/2003, female, with 130 ventrals). There is no locality information available for SMF 17819. ZSM 0595/2003 was collected at the Rio Parana in Porto Tibiriça, Sao Paulo, Brazil. This is approximately 1300 km distant from the distribution range of H. apiaka. The origin of a speciemen is probably an important feature in order to assign it to one of the two species (for information on references, see Suppl. material 3).

The only known specimens of H. apiaka are from northern Mato Grosso and southern Pará (Fig. 1b).

Morphology remark

Regarding the number of dorsal scale roles at mid-body in H. apiaka, there is contradictory information. Moraes-da-Silva et al. (2019) states that H. apiaka has 19–21 dorsal scale rows at mid-body, which would eliminate this character as a diagnostic character to distinguish it from H. angulatus. This would leave only the number of ventrals in females as a sure diagnostic trait. However, in the original species description, Kawashita-Ribeiro et al. (2013) report 21–22 scale rows. At this point, we trust the data given by Kawashita-Ribeiro et al. (2013), as both publications examined the same specimens.