Mulloides armatus De Vis, 1884

Uiblein, Franz, Gouws, Gavin, Johnson, Jeffrey W., Lobel, Phillip S. & Shaheen, Shaker, 2020, Junior synonymy of Mulloides armatus and intraspecific comparisons of the yellowstripe goatfish Mulloidichthys flavolineatus (Mullidae) using a comprehensive alpha-taxonomy approach, Cybium 44 (2), pp. 137-155 : 141-146

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).

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

Figures

Figure 1. – A: HT of Mulloides armatus, QM I.122, 118 mm SL, Queensland, E Australia, western SW Pacific (Jeff Johnson); B: M. flavolineatus flavolineatus, AMS I.20269-007, 253 mm SL, Norfolk Island, E Australia, SW Pacific (Doug Hoese); C: Shoal of adult/subadult M. f. flavicaudus, Dahab, Egypt, Gulf of Aqaba, Red Sea (Kristina Vackova); D: Shoal of adult/subadult M. f. flavolineatus, associated with snappers, La Digue and Inner Islands, Seychelles, Indian Ocean proper (Massimiliano Finzi). Scale bars = 2 cm for the respective fish on top.

Figure 2. – Standard length against total length in 12 adult/subadult specimens of Mulloidichthys flavolineatus flavolineatus from the SW Pacific, with projected placement of the HT of M. armatus, allowing approximation of standard length.

Tables

Table I. – Quantitative morphological and meristic characters and one qualitative character for the holotype of Mulloides armatus and adults of M. flavolineatus flavolineatus of four Pacific populations. * For determination of SL in this specimen see Materials & Methods section.

	Mulloides					Mulloidichthys flavolineatus flavolineatus
	armatus	SW Pacific				Wake Atoll			Hawaiian archipelago					Other Pacific
	HT	Min Mean Max n				Min Mean Max n Min Mean Max n Min Mean Max n
Morphometric characters
Total length (mm)	152	120 204.7		322	12	268 276.3		286	3 154 209.6			287	7 120 199.0			275	12
SL (mm)	118*	93	165.7	253	14	206 213.3		221	3 119		179.6	287	10	95	156.3	235	15
in % TL
SL	78	75	77.8	80	12	77	77.2	77	3	76	78.4	80	7	76	77.7	79	12
in % SL
Body depth at first dorsal-fin origin	23	22	23.7	25	14	21	22.0	23	3	22	23.8	26	10	22	23.6	25	15
Body depth at anal-fin origin		19	20.0	21	14	17	18.5	19	3	19	20.4	22	10	18	19.9	21	15
Half body depth at first dorsal fin origin	18	18	19.2	21	14	16	16.9	18	3	17	19.5	21	10	17	19.1	21	15
Half body depth at anal fin origin		13	14.3	15	14	12	12.5	13	3	14	14.9	16	10	13	14.5	16	15
Caudal-peduncle depth	8.9	8.6	9.0	9.6	14	9.1	9.4	9.7	3	8.5	9.2	9.7	10	8.4	9.1	9.5	15
Caudal-peduncle width	4.2	3.6	3.9	4.2	14	3.4	3.6	3.7	3	3.2	4.0	4.6	10	3.0	4.0	4.5	15
Maximum head depth	20	19	20.3	22	14	21	21.4	22	3	19	20.5	22	10	19	20.7	22	15
Head depth through eye	17	16	16.9	18	14	18	18.2	18	3	16	16.4	17	10	16	17.0	18	15
Suborbital depth	10	9.0	10.0	11	14	9.9	11.0	12	3	8.5	9.7	11	10	8.2	9.6	10	15
Interorbital length	8.1	7.6	8.6	9.3	14	8.0	8.2	8.4	3	7.4	8.3	8.8	10	7.8	8.5	9.5	15
Head length	31	28	29.7	31	14	32	32.1	33	3	27	29.0	30	10	28	30.0	32	15
Snout length	13	12	13.5	15	14	14	14.2	15	3	12	13.0	14	10	12	13.0	14	15
Postorbital length	9.9	9.3	10.3	11	14	10	10.4	10	3	9.3	10.0	11	10	9.3	10.1	11	15
Orbit length	7.6	5.6	7.3	8.2	14	7.8	7.9	8.1	3	5.8	6.9	8.3	10	6.5	7.4	8.6	15
Orbit depth	6.7	5.1	6.4	7.2	14	6.8	6.9	7.0	3	5.1	6.0	6.9	10	5.8	6.5	7.7	15
Upper-jaw length	9.6	8.3	9.0	9.8	14	8.9	9.6	10	3	8.7	8.9	9.3	10	8.4	8.9	9.9	15
Lower-jaw length	9.2	8.0	8.6	9.3	14	8.6	9.3	9.7	3	8.3	8.6	8.9	10	7.8	8.6	9.5	15
Snout width	7.4	6.1	7.1	8.4	14	5.6	5.9	6.3	3	5.9	6.7	7.4	10	5.9	6.6	7.7	14
Barbel length	21	19	20.5	23	14	23	23.0	23	3	18	19.0	20	10	18	19.9	22	15
Maximum barbel width	0.6	0.6	0.8	1.0	14	0.7	0.8	0.9	3	0.6	0.7	0.9	10	0.6	0.8	1.1	15
First predorsal length	40	37	40.0	42	14	41	42.2	43	3	38	39.4	41	10	38	39.9	42	15
Second predorsal length		65	66.5	69	14	66	67.1	69	3	65	66.8	68	10	64	66.2	68	15
Interdorsal distance		13	15.0	16	14	14	15.1	16	3	14	15.7	17	10	13	15.2	17	15
Caudal-peduncle length	20	20	22.2	24	14	20	20.9	22	3	21	22.2	24	10	21	22.4	24	15
Preanal length		65	67.4	71	14	64	67.3	71	3	67	67.6	70	10	65	66.8	69	15
Prepelvic length	33	31	33.6	36	14	34	35.9	37	3	31	33.1	35	10	32	33.7	36	15
Prepectoral length	31	30	31.6	33	14	33	34.4	35	3	30	31.4	34	10	30	32.0	34	15
Second dorsal-fin depth		19	20.6	21	14	17	18.8	20	3	19	21.2	22	10	18	20.7	22	15
Pelvic-fin depth	23	22	23.9	25	14	22	22.3	22	3	23	24.3	26	10	22	23.9	26	15
Pectoral-fin depth	16	16	17.4	19	14	16	16.2	16	3	16	17.7	19	10	16	17.6	19	15
Length of first dorsal-fin base		12	14.5	16	14	14	13.6	14	3	13	14.5	16	10	13	14.4	16	15
Length of second dorsal-fin base	13	11	12.4	14	14	11	12.3	13	3	11	12.2	13	10	11	12.0	13	15
Caudal-fin length		29	30.7	32	11	32	32.2	32	3	28	30.0	32	6	29	31.1	33	12
Length of anal-fin base	11	8.6	9.5	11	14	8.5	8.6	8.7	3	8.6	9.7	11	10	8.1	9.4	11	15
Anal-fin height	13	12	13.5	15	14	15	15.1	16	3	13	13.8	15	9	13	14.5	16	13
Pelvic-fin length	21	19	20.8	22	14	20	21.1	22	3	19	20.4	22	10	19	21.2	23	15
Pectoral-fin length	19	18	19.8	21	14	22	22.7	23	3	18	19.8	22	10	19	20.4	22	14
Pectoral-fin width	4.0	4.1	4.5	4.9	13	4.5	4.8	5.1	3	3.9	4.4	5.0	10	4.1	4.5	5.1	15
First dorsal-fin height		19	20.8	22	14	22	23.6	25	3	20	20.4	22	10	19	20.9	23	15
Second dorsal-fin height		13	14.2	16	14	15	15.5	16	3	14	14.3	15	10	13	14.9	16	15