Pristolepis procerus, Plamoottil, 2017

Pristolepis procerus View in CoL , a junior synonym of P. malabarica

Pristolepis procerus was described by Plamoottil (2017: European Journal of Zoological Research ) from the Chaliyar , a 169 km long river draining the Western Ghats mountains in Kerala, India. No precise type locality was provided, though it was mentioned that the holotype and paratype were collected from Kozhikode District. The poorly-written description listed ambiguous diagnostic characters, making it impossible to unambiguously distinguish and separate the ‘new’ species from its congeners .

Based on two specimens (the holotype and paratype), Pristolepis procerus was described as having 13 dorsal-fin rays. However, our series of 18 specimens of Pristolepis from various localities in the Chaliyar River (though no precise type locality was originally designated, we henceforth consider the Chaliyar River as the type locality for the purpose of this paper) includes individuals with 12 (4), 13 (13) and 14 (1) dorsal-fin rays. All of these specimens are separated genetically by a raw pair-wise distance of only 1% in their mitochondrial COI gene sequences (GenBank: PV450154 with 12 dorsal-fin rays; PV450155, PV450159 and PV450164 with 13 rays; PV450158 with 13 rays; and PV450157 with 14 rays). The range of 12–14 dorsal-fin rays of topotypic material of P. procerus thus covers the count of 12 mentioned in the description of P. malabarica ( Günther, 1864) , rendering this feature useless as diagnostic character.

In its original description, Pristolepis procerus was also distinguished from P. malabarica by a deeper body (47.2–47.6% SL vs. 41.4–45.5% SL), a character that inspired the specific name (the Latin word ‘ procerus ’ means ‘tall’). Additional characters considered diagnostic for P. procerus in the original description were head length, and number of lateral-line scales. A critical re-examination of the holotype of P. procerus revealed that the body depth is 47.9% SL, with body depth of 18 topotypes of P. procerus ranging from 46.5–53.2% SL. This range overlaps with the range of body depth of topotypes (N=12) of P. malabarica , and additional specimens (N=2) from the Manimala River (43.8–52.1% SL). Similarly, the head length of the holotype (37.9% SL), and the range calculated from 18 topotypes of P. procerus (33.9–39.1% SL) were within the range of 12 topotypes, and two additional specimens of P. malabarica (31.9–36.5% SL). Both these features thus have no value as diagnostic characters.

The number of lateral-line scales in the type series of P. procerus has been inconsistently listed in the original description (Plamoottil 2017, European Journal of Zoological Research), i.e., 19–21/10 lateral-line scales in Table 1 on p.41, and 19–21/10–11 lateral-line scales under comparative account on p.42. Our 18 topotypic specimens of P. procerus from the Chaliyar have 20–23/5–8 lateral-line scales (20/ 9 in the holotype by our count), which is consistent with those obtained from 12 topotypes, and two additional specimens of P. malabarica (19–22/5–8). The difference in counts of the posterior part of the lateral line, however, is likely due to differences in the method of counting. In the present study, lateral-line scales were counted following the method of Hubbs et al. (2004) up to the end of the hypural plate. In the original description of P. procerus , however, scales on the posterior portion of the lateral line included those beyond this landmark, i.e., those on the caudal-fin base. Our recounting of the lateral-line scales of the holotype of P. procerus yielded a count of 20/9, matching the counts of P. malabarica . Based on the overlapping morphometric data and counts, and the lack of any other diagnostic characters, Pristolepis procerus cannot be distinguished from P. malabarica . We therefore synonymize the former name with the latter.