Dorsal rays X,16, the first two soft rays simple; anal rays III,7, the first spine very small and difficult to detect; first ray simple; pectoral rays 21 (19), the upper most and lower most rays simple; branched pelvic rays I,5; branched caudal rays 13; simple upper and lower segmented caudal rays 4; upper and lower procurrent caudal rays 13; lateral line scales 63 (64); scales above lateral line to origin of dorsal fin 5; scales below lateral line to origin of anal fin 12; gill rakers 8+19 (8 +18) (Table 1).

Table 1. Download as CSV 

Counts of dorsal rays, anal rays, pectoral rays, lateral line scales, and gill rakers of the species of Luzonichthys.

	Dorsal rays	Anal rays	Pectoral rays	Lateral line scales	Gill rakers
L. seaver	X,16	III,7	19-21	63-64	8+18-19
L. earlei	X,16-17	III,7	19-21	59-68	6-9+19-22
L. microlepis	X,16	II,9	21-22	70-76	7-8+21-23
L. taeniatus	X,16	III,7	19	56-60	7+19
L. waitei	X,15-17	III,7	17-21	51-59	7-10+19-22
L. whitleyi	X,16	III,7	19-22	65-74	7-9+20-23
L. williamsi	X,16	II,9	21-23	70-78	7-8+21-22

Body moderately elongate, the depth 3.86 (4.6) in SL, and compressed, the width 1.83 (1.25) in BD; head length 3.54 (3.41) in SL; snout short and bluntly rounded, 4.0 (3.86) in HL. Orbit diameter 3.43 (3.8) in HL; the least width of interorbital space 3.0 (3.38) in HL; caudal peduncle depth 2.4 (2.45) in HL; caudal peduncle length about twice its depth, 1.09 (1.23) in HL. Mouth terminal and oblique, the maxilla reaching posterior to rear edge of pupil but not posterior to rear edge of orbit; the upper jaw length 1.6 (1.93) in HL; corners of maxilla rounded, its greatest depth about equal to pupil diameter. Opercle with 2 flat spines, the lower acute, in line with center of eye and opercular flap, the upper spine at dorsal end of gill opening poorly developed. Lateral line only slightly arched above pectoral fin, gradually descending below soft portion of dorsal fin, straightening toward the peduncular region; scales on body ctenoid; head scaled except snout; dorsal, anal, and pelvic fins naked; caudal fin with small scales extending about three-fourths distance to posterior margin; basal fifth of pectorals with small scales. Origin of dorsal fin above eighth lateral-line scale; first dorsal spine short, 8.0 (9.0) in head; fourth dorsal spine longest, 2.4 (2.45) in HL; longest dorsal soft ray 2.4 (2.45) in HL; origin of anal fin below base of sixth dorsal soft ray; first anal spine very short, about 12(13.5) in HL; second anal spine 6.0 (6.75) in HL; first anal soft ray very slender and only partly segmented, 2.4 (2.7) in HL; longest anal soft ray 2.0 (2.45) in HL; caudal fin forked, with filamentous rays, the fin length 4.05 (3.83) in SL, the caudal concavity 8.5 (8.36) in SL; middle pectoral rays longest, 3.86 (4.38) in SL; origin of pelvic fins below lower base of pectorals; second pelvic soft ray longest, 5.67 (6.57) in SL (Table 2).

Table 2. Download as CSV 

Proportional measurements of type specimens of Luzonichthys seaver expressed as percentages of standard length

	Holotype BPBM 41205	Paratype BPBM 41206
Standard length (mm)	42.5	46
Body depth	25.9	21.7
Body width	14.1	17.4
Head length	28.2	29.3
Snout length	7.1	7.6
Orbit diameter	8.2	8.7
Interorbital width	9.4	8.7
Upper jaw length	17.6	15.2
Caudal peduncle depth	11.8	12.0
Caudal peduncle length	25.9	23.9
Predorsal length	35.3	34.8
Preanal length	62.4	70.0
Prepelvic length	33.0	32.6
First dorsal spine	3.5	3.3
Second dorsal spine	9.4	8.7
Third dorsal spine	10.6	8.7
Forth dorsal spine	11.8	12.0
Longest dorsal spine	11.8	12.0
First anal spine	2.4	2.2
Second anal spine	4.7	4.3
First anal ray	11.8	10.9
Longest anal ray	14.1	12.0
Caudal fin length	24.7	26.1
Caudal concavity	11.8	12.0
Pectoral fin length	25.9	22.8
Pelvic spine length	9.4	7.6
Pelvic fin length	17.6	15.2

Color of holotype in life: head excluding operculum predominately yellow (many scales with yellow margins and pink centers), yellow extending posteriorly on upper half of body from a line starting at approximately the tip of the opercular flap and top of pectoral fins to the eighth dorsal ray, fading to bright pink posteriorly. Operculum to lower half of body salmon pink. Pectoral and pelvic fins pale. Dorsal fins yellow with bases of rear dorsal rays pink. Anal fin rays yellow with pale membranes. Upper and lower base of caudal fin pink, extending posteriorly to approximately halfway to the tips; center of base of caudal fin white, fading to pale; posterior half of caudal fin yellow. Lower base of caudal peduncle with yellow band (Fig. 1).

Figure 1.

Holotype of Luzonichthys seaver, BPBM 41205, Pohnpei, Micronesia. Photo: Brian D. Greene.

Color of holotype in alcohol: Pale, all fins colorless except the caudal which has purple spots on the base of each of the upper and lower segments, the upper extending anteriorly, dorsally on the caudal peduncle.

Dorsal rays X,16; anal rays III,7; pectoral rays 19-21; lateral line scales 63-54; gill rakers 8+18-19; Body moderately elongate, the depth 3.86-4.6 in SL; head length 3.41-3.54 in SL; snout 3.86-4.0 in HL; caudal fin forked, with filamentous rays, caudal concavity 8.36-8.5 in SL; pectoral fins 3.86-4.38 in SL; pelvic fins 5.67-6.54 in SL.

Named seaver, as a noun in apposition, for the Seaver family in recognition of support from the Seaver Institute for marine research.

Type specimens of L. seaver were collected from Pohnpei, Micronesia. A single larva of what may be this species (98.2-99.5% similarity at CO1) was collected in Moorea, French Polynesia (BOLD: FPFLB281-12; GenBank: KJ967845.1; Hubert et al. 2014​), but the taxonomic identity of the Moorea specimen could not be confirmed by the authors. Therefore, it is possible that adults of this species will be discovered in Moorea and other locations across the Pacific.

Luzonichthys seaver is distinct from all other species within the genus in life coloration. It is most similar in color to L. earlei (Fig. 2); however, it differs from that species in coloration of head, upper half of body, and dorsal and anal fins (yellow in L. seaver, compared with orange in L. earlei), and in the distinctive color pattern on the caudal fin (bright pink blotches on the base of both caudal lobes with bright yellow distally in L. seaver, compared with drab, diffuse orange blotches and pale yellow distal caudal lobes in L. earlei). We have examined enough individuals of L. earlei from many localities to confirm that these color characteristics do not vary signigicantly within that species. Morphologically, it differs from all other species except L. earlei in number of lateral line scales (63-64, compared with 51-60 or 65-78 for other species), and from all other species except L. whitleyi in caudal concavity (8.4-8.5 in HL, compared with 4.0-8.3 for other species). It further differs from all other species except L. earlei, L. waitei and L. taeniatus in number of gill rakers (8+18-19, compared with 7-10+20-23 for other species), and from L. williamsi and L. microlepis in number of anal-fin spines and rays (III, 7 compared with II, 9), as well as snout length, orbit diameter, and caudal peduncle depth (Table 3). Luzonichthys seaver is further distinct from L. williamsi in its body depth and pectoral fin length, and from L. taeniatus in snout length, caudal peduncle depth, and longest dorsal spine (Table 3). Overall, L. seaver is most similar morphologically to L. earlei and L. whitleyi; however, in addition to character differences outlined above, it can be further distinguished from these two species by caudal peduncle depth (both species) snout length (L. whitleyi), and head length (L. earlei) (Table 3​). Molecular data are not used for comparative purposes in this description because these data do not exist for any of the other species of Luzonichthys. The CO1 barcodes produced in this study represent the first sequences publicly available for this genus, aside from the afore mentioned and previously unclassified larval specimen from Moorea.

Table 3. Download as CSV 

Comparison of selected morphological characters for species of Luzonichthys.

	Character	L. seaver	L. earlei	L. microlepis	L. taeniatus	L. waitei	L. whitleyi	L. williamsi
Body depth	in SL	3.9-4.6	3.6-4.1	4.1-4.4	3.7-4.0	3.3-3.8	4.15-5.0	5.2-5.4
Head length	in SL	3.4-3.5	3.15-3.4	3.5-3.7	3.3-3.5	3.0-3.6	3.4-3.8	3.4-3.5
Snout length	in HL	3.9-4.0	3.9-4.3	4.0-4.3	4.2-4.4	3.7-4.1	4.2-4.8	4.3-4.6
Orbit diameter	in HL	3.4	3.1-3.9	4.1-4.4	3.0-3.5	3.5-3.9	3.2-3.6	2.7-3.3
Caudal peduncle depth	in HL	2.4-2.5	2.6-2.9	2.5-2.7	1.5	2.3-2.6	2.5-2.9	2.8-2.9
Caudal concavity	in SL	8.4-8.5	6.1-7.3	6.0-6.8	5.1-5.5	4.0-5.6	5.2-9.0	6.7-8.3
Longest dorsal spine	in HL	2.4-2.5	2.1-2.6	2.4-2.8	2.2-2.4	2.2-2.6	2.0-2.6	2.2-2.5
Pectoral fin length	in SL	3.9-4.4	3.7-4.0	4.1-4.7	3.6-3.7	3.2-3.5	3.7-4.4	4.4-4.7
Pelvic fin length	in SL	5.7-6.6	4.4-5.2	5.0-5.8	4.6-4.9	3.9-4.7	4.6-6.0	4.8-5.8

Figure 2.

Luzonichthys earlei, from the Hawaiian Islands. Photo: John E. Randall.