Lethrinus microdon Valenciennes, 1830

Damadi, Ehsan, Yazdani Moghaddam, Faezeh & Ghanbarifardi, Mehdi, 2024, Taxonomic characterization of five species of emperor fishes (Actinopterygii: Eupercaria: Lethrinidae) based on external morphology, morphometry, and geographic distribution in the northwestern Indian Ocean, Acta Ichthyologica et Piscatoria 54, pp. 115-124 : 115-124

Lethrinus microdon Valenciennes, 1830

English common name: smalltooth emperor Fig. 2 D

Lethrinus microdon Valenciennes in Cuvier and Valenciennes, 1830. — Cuvier and Valenciennes (1830): 295, Holotype: MNHN 0000-9073; Type locality: Indonesia: Molucca Islands, northeastern Pulau Buru.

Material examined.

ZMFUM - LE- 35-43 , 9 specimens (Suppl. material 1), May 2022 to March 2023, depth 25– 50 m.

Description.

Dorsal-fin rays X, 9; anal-fin rays III, 8; pectoral-fin rays 13; tubed lateral-line scales 47–48; 4.5 transverse scale rows above lateral line; 16–17 transverse scale rows below lateral line; 15–16 lower series of scale around caudal-peduncle; low-bodied forms; forked caudal fin; no scales on inside of the pectoral fin base; conical teeth; cheek without scales; body gray; fins brown.

Morphometrics. To characterize the morphological variation between Lethrinus species, morphometric features were analyzed. The MANOVA results showed no significant difference between males and females, the sexes were pooled in all analyses (0.0511 <P <1.0000) (Suppl. material 2). In the one-way ANOVA analysis, 17 out of 22 traits were found to be significant (P <0.0000) (Suppl. material 2). These traits included 15 morphometric and two meristic traits (Suppl. material 2). The Tukey post hoc test results showed a significant difference between all five species (P <0.05). Specifically, the Tukey post hoc tests for metric traits showed the most significant differences between L. crocineus and L. microdon , while the differences in meristic variables were most significant between L. microdon and the other species (data not shown). The boxplot of total length shows that L. nebulosus is generally larger than the other species; L. microdon is medium-sized and the other species are smaller (Fig. 3 ). As expected, the first principal component (PC 1) on metric characters accounted for the highest proportion of variance (99.2 %) (Fig. 4 A ). On the PC 1 axis, L. nebulosus and L. microdon showed a high differentiation from L. borbonicus , L. crocineus , and L. lentjan in the majority of of the measured morphometric traits, including body depth, caudal peduncle depth, pectoral fin length, preorbital length, and caudal fin length. On the PC 2 axis, L. crocineus showed significant differences from L. microdon . PCA on the morphometric traits showed a notable overlapping between L. borbonicus and L. lentjan on PC 1 and PC 2. For the majority of meristic traits, L. microdon showed a high differentiation from the other species due to its significant scale rows above the lateral line and supratemporal scale patch (Fig. 4 B ). The PCA results (Fig. 4 ) were well supported by the DFA analyses (data not shown). The DFA correctly classified 100 % of the specimens, which was confirmed by cross-validation of specimens to species based on morphometric and meristic features.

Figures

Figure 2. Lethrinus crocineus (A), ZMFUM - LE- 12, (Photo by E. Damadi); Lethrinus nebulosus (B), ZMFUM - LE- 48, (Photo by E. Damadi); Lethrinus lentjan (C), ZMFUM - LE- 8, (Photo by E. Damadi); Lethrinus microdon (D), ZMFUM - LE- 35, (Photo by E. Damadi).

Figure 3. Total length data of the five of Lethrinus species samples in the presently reported study in the Persian Gulf and the Gulf of Oman.

Figure 4. Principal component analysis (PCA) results of the five of Lethrinus species samples in the presently reported study in the Persian Gulf and the Gulf of Oman; (A) morphospace plotted on 14 morphometric traits; and (B) morphospace plotted on 10 meristic traits morphometric traits; L. borbonicus (green), L. crocineus (yellow), L. lentjan (red), L. microdon (blue), L. nebulosus (black). LLS = lateral-line scales; SALL = scale rows above lateral line; SBLL = scale rows below lateral line; LSACP = scale around caudal-peduncle; SPS = supratemporal patch of scales; BD = body depth; HL = head length; POL = preorbital length; UJL = upper-jaw length; CPD = caudal-peduncle depth; CPL = caudal-peduncle length; PDL = predorsal length; PAL = preanal length; PPL = prepelvic length; LDFB = length dorsal-fin base; LAFB = length anal-fin base; LPF = length pectoral fin; LCF = length caudal fin; OD = orbit diameter [% of HL].