Pempheris rhomboidea

Randall, John E., Victor, Benjamin C., Alpermann, Tilman J., Bogorodsky, Sergey V., Mal, Ahmad O., Satapoomin, Ukkrit & Bineesh, K. K., 2014, Rebuttal to Koeda et al. (2014) on the Red Sea fishes of the perciform genus Pempheris, Zootaxa 3887 (3), pp. 377-392 : 385-387

Pempheris rhomboidea vs P. nesogallica

The third species reported from the Red Sea by Koeda et al. (2014), Pempheris nesogallica , was described from Mauritius by Cuvier in Cuvier & Valenciennes, 1831. No DNA sequences are assigned to the species by Koeda et al. (2014). Nevertheless, they distinguish it from P. rhomboidea (their Red Sea “ P. mangula ”) arbitrarily by smaller eye size and the lack of stripes. They write, “Of two existing syntypes of P. nesogallica from Mauritius, one is designated as the lectotype, the other is re-identified as P. mangula ; P. nesogallica is presently known only from the southern Red Sea” (the “only” must refer to ostensible range within the Red Sea itself). Randall D. Mooi examined the two syntypes of P. nesogallica and found them remarkably similar (as may also be seen in Fig. 6 of Koeda et al. (2014)). All the meristic data are the same, or at most one count different.

In their key, Koeda et al. (2014) distinguish Pempheris rhomboidea (their “ P. mangula ”) from P. nesogallica by two characters. The first is eye diameter: 13.0–15.3% SL for “ P. mangula ” and 11.6–12.8% for P. nesogallica . We invite the reader to measure the eye diameter as a percentage of the SL of the syntypes of P. nesogallica in their Fig. 6 A and B. We obtain an eye diameter of 13.0% SL for the fish of their Fig. 6 A, hence barely P. rhomboidea , and 14.1% for the fish of their Fig. 6 B, thus also P. rhomboidea . Therefore, if we follow Koeda et al. (2014), both syntypes of P. nesogallica should now be reidentified as P. rhomboidea . Actually, from our measurements of the eye diameter of all specimens of P. nesogallica and P. rhomboidea available to us, specifically from the type regions, we can find no difference in eye size between these two species ( Fig. 4 ). We repudiate here the designation of MNHN-IC-A-0222 (“MNHN A222” in Koeda et al. (2014)) as the lectotype of P. rhomboidea by Koeda et al. (2014) because the basis for their selection is erroneous.

Their second character, the presence or absence of stripes is also mistaken. Both species usually have a striped pattern in life from a dark bronze or copper spot on each scale, but can vary from being nearly uniform to having a striped pattern when preserved ( Figs. 5 and 6 ). However, we have found a viable morphological character to separate Pempheris nesogallica from P. rhomboidea : the length of the pectoral fin relative to the standard length. This fin is the most durable of the fins of preserved specimens of Pempheris . It is measured from the most anterior end of the fin base (the base extends to the edge of the opercular membrane) to the tip of the longest ray. We measured both fins of each fish and used the longest measurement. We have taken pectoral-fin lengths of P. nesogallica only from specimens from Mauritius and Madagascar and of P. rhomboidea only from specimens from the northern Red Sea and the Mediterranean Sea. Nineteen specimens of P. nesogallica , 65.5–150 mm SL, have a pectoral-fin length of 3.2–3.55 in SL. By contrast, 12 specimens of P. rhomboidea , 76–130 mm SL, have a pectoral-fin length of 2.85–3.2 in SL. The two species are very similar in meristic characters. Only the number of anal soft rays shows a difference, 38–45 for P. nesogallica vs. 36–41 for P. rhomboidea ( Table 1).

Koeda et al. (2014) write “ Pempheris nesogallica is widely distributed in the Western Indian Ocean, but has only been collected from the southern part of the Red Sea.” In their material for the species, they list only the single lot (of three specimens) from the Red Sea: in the collection of the Hebrew University of Jerusalem, HUJ 16363, 3: 109–111 mm SL, collected from Eritrea. A photograph of HUJ 16363 supplied by Dr Daniel Golani shows one specimen to be an obvious P. flavicycla , with a relatively small eye, a yellow ring around the pupil, and a black border along the full length of the anal fin. The remaining two fish are P. rhomboidea . A second lot of five specimens from the Hebrew University, HUJ 16369, were misidentified by Koeda et al. (2014) as “ Pempheris adusta ” (Appendix 1, p. 325). Photographs of the specimens of this lot from Dr. Golani reveal that two are clearly P. flavicycla , and the other three are P. rhomboidea .

Figures

FIGURE 4. Orbit diameter vs. standard length for specimens of Pempheris nesogallica (open circles) and P. rhomboidea (closed squares).

FIGURE 5. Pempheris rhomboidea, BPBM 18425, 123 mm SL, Gulf of Aqaba (J. E. Randall).

FIGURE 6. Pempheris nesogallica, BPBM 20144, 117 mm SL, Mauritius (J. E. Randall).