Taxonomic status of Mulloides armatus De Vis, 1884

In the holotype of Mulloides armatus the snout is clearly longer than the postorbital distance (13 vs. 9.9% SL; see Tab. I). Also, dentition, preserved colour (Fig. 1A), and the 27 total gill rakers and 16 pectoral-fin rays counted for this specimen (Tab. I) agree well with the generic diagnosis of Mulloidichthys (Uiblein, 2011) . The number of gill rakers on the lower limb (n = 19) agrees with the diagnosis of M. flavolineatus, but also with other congeners such as M. pfluegeri (Uiblein, 2011) . Based on the supposed TL of 6 inches (= 152 mm) reported in the original description, the SL of the M. armatus HT could be calculated when plotting SL against the TL in 12 SW Pacific specimens of M. flavolineatus (Fig. 2) The resulting SL value of 118 mm expressed in % TL (= 78%) closely matches the average values obtained for the reference population (Tab. I) as well as for all studied populations (Tabs I, II), M. f. flavicaudus (Tab. II), and adult and juvenile M. flavolineatus (overall range 75-81% for adults and 78-80% for juveniles; Tab. III). Of the total 40 morphometric body- and fin-shape characters, 30 characters could be obtained from the HT, expressed in % SL using the determined SL value and subsequently compared (Tab. I). Two important meristic characters, first dorsal-fin spines and the number of lateral-line scales, could not be obtained from the type due to damage.

The holotype of M. armatus overlaps with the SW Pacific reference population in morphological and meristic characters except for a minimal deviation in pectoral-fin width (Tabs I, IV). Its body is uniformly brownish and the fins uniformly pale brown and partly hyaline, very similar to many preserved specimens examined. The number of lateral-line scales, indicated in the original description to be 40, would be clearly out of the range for all M. flavolineatus examined (33-38). The most plausible explanation for this deviation is that De Vis (1884) included the 3-4 scales on the base of the caudal fin. Eight spines in the first dorsal fin were encountered in all specimens examined of M. flavolineatus, which is also in contrast to the seven spines indicated in the original description of M. armatus . When examining this character qualitatively, we found that it was well detectable only in only nine of 14 adult SW Pacific specimens (64.3%; Tabs I, IV), while the minute first spine is difficult to detect in five specimens (35.7%) and, hence, could be easily overlooked. Difficulties to detect this spine have been also documented in all other populations studied (see also the intraspecific comparisons below).

Wake Atoll2 12 1Hawaiian Archipelago7 212 6 2Other areas of Pacific710 41 14 5 1Entire Pacific (A)1031 8111 28 9 22Indian Ocean (B)1024 314 18 4 16 M. f. flavicaudus (C) 1018 1816 53 11 Chi2 test:ns(A, B) C**

We conclude that Mulloides armatus is a junior synonym of M. flavolineatus .