Lutjanus rufolineatus (Valenciennes, 1830)

Species: Lutjanus rufolineatus (Valenciennes, 1830) View in CoL

Materials Examined

India, Andaman Island, South Andaman Coast, Andaman Sea, Mazar Pahar (11º39’23.95”N 92º 45’42.99”E), Fahmeeda Parveen P S, Ameen Ummath, Mohammed Ramees PV Collectors, 20 March 2023, 2 specimens (PUMBLRF001 147.3 mm SL Female, PUMBLRF002 124.9 mm SL Female). Andaman Island, South Andaman Coast, Andaman Sea, Netaji Subash Chandra Boss Island (11º40’7.27”N 92º45’54.28”E), Ameen Ummath, Samrat Kalita Collectors, 11 April 2023, 1 Specimen (PUMBLRF003 103.6 mm SL Male).Andaman Island, South Andaman Coast, Bay of Bengal, Collinpur (11º40’24.98”N 92º34’20.71”E), Fahmeeda Parveen P S, Ameen Ummath, Collectors, 2 June 2023, 1 Specimen (PUMBLRF004 130.1 mm SL Female). Andaman Island, South Andaman Coast, Bay of Bengal, Rutland (11º29’28.76”N 92º35’39.65”E) Fahmeeda Parveen P S, Ameen Ummath Collectors, 5 June 2023, 2 specimens (PUMBLRF005 136.3 mm SL Male, PUMBLRF006 147.9 mm SL Female).

Diagnosis

Lutjanus rufolineatus has fin formula, Dorsal XI 13–14; Anal III 8; Pectoral 15–16; Lateral Line 47–49 (see Table 1 View TABLE 1 ). Body depth 2.6–2.8 in SL. Head length 2.4–2.5 in SL. Eye diameter 3.4–3.8 in HL. Interorbital space 5.1–6.0 in HL. Snout slightly pointed and 2.9–3.7 in HL. Distinct preopercular notch. Well-developed inter-opercular knob. The preopercle covered with scales, except for the rear end. Posterior end of preopercle finely serrated. Crescentic vomerine tooth patch without a medial posterior extension. Smooth tongue without granular teeth. Dorsal and anal fins with rounded posterior profile. Presence of scale rows at the base of dorsal and anal soft rays as well as pectoral and caudal fin. Scale rows on the back rise obliquely above the lateral line. Caudal fin slightly emarginate or truncate. The meristic counts and body colouration of the collected specimens confirms that the specimens obtained are Lutjanus rufolineatus and are distinctly different from its congeners.

Distribution

Indo-West Pacific: Maldives; Andaman and Nicobar Islands (Present Study); western Pacific from southern Japan to Indonesia and northern Australia; eastward in southern Pacific to Samoa and Tonga ( Allen 1995; Anderson et al. 1998; Hoese et al. 2006; Allen & Erdmann 2012).

Colour

In fresh condition, generally reddish or pink, with ventral side white or silvery-white; Lateral side of the body with a series of about 10 yellow stripes; A faint black spot below the anterior part of soft dorsal fin rays, above the lateral line. All fins are yellowish, whereas the pelvic fin has a white hue. The dorsal portion of the pectoral fin axil is brown. Following the fixation in formalin, colouration generally fades to tan or yellowish with the black spot on the back.

Description

Body is moderately elongated and laterally compressed; convex dorsal profile with greatest body width (35.1–36.8 in % SL) (see Table 2 View TABLE 2 ); Eyes are large in size (25.6–28.7 in % HL) located midpoint to the posterior margin of upper jaw; Mouth terminal, oblique and pointed; Two pairs of nostrils present in front of the eye; Posterior nostril elliptical; Canine teeth present in both upper and lower jaw; Body with ctenoid scales; Single lateral line present on both sides; Soft rays of the dorsal, anal, pectoral and pelvic fins are branched; The fifth dorsal spine surpasses other dorsal spines in size, with the succeeding and preceding spines diminishing in length; Caudal fin with branched medial rays.

DNA Barcoding and Data Analysis

The identity of Lutjanus rufolineatus was further validated through the sequencing of the cytochrome oxidase subunit I (COI) gene. PCR amplification of genomic DNA extracted from the specimen produced a band approximately 690 bp in length, which, after removal of ambiguous bases, yielded a 652 bp sequence. This sequence was subsequently submitted to the NCBI database under the GenBank accession number OR399158. Analysis confirmed that all nucleotides represented functional mitochondrial sequences, with no stop codons present. The sequence showed a high identity match (99.85%) with the COI sequence of L. rufolineatus voucher IRD BMF-316.2 (MN870411.1) in the NCBI database. Phylogenetic reconstruction produced well-defined trees, with distinct species-specific clades. In a neighbour-joining tree, the Andaman isolate of L. rufolineatus formed a unique clade alongside other lutjanid species, strongly supported by a bootstrap value of 100 ( Figure 3 View FIGURE 3 ). Genetic distances were calculated using the Kimura-2-Parameter (K2P) model in MEGA X. Both intraspecific and interspecific genetic distances were assessed, with the intraspecific distance between the Andaman isolate (OR399158) and other L. rufolineatus sequences estimated at 0.002. Interspecific distances between the Andaman isolate and other species within the genus ranged from 0.029 to 0.139 (see Table 3 View TABLE 3 ).

Discussion

The family Lutjanidae presents significant taxonomic challenges due to the morphological similarities among its species, which complicate accurate identification. Many species within the family resemble each other externally, making species-level identification heavily reliant on live colour patterns. However, colour patterns often fade during preservation, leading to further complications and misidentifications in preserved specimens. One notable example is Lutjanus rufolineatus , which was initially considered a junior synonym of Lutjanus boutton (Lacepède, 1802) ( Allen and Talbot 1985; Allen 1985). This misconception was later rectified by Allen (1995), who confirmed L. rufolineatus as a valid, distinct species.

In this study, we analysed the meristic characteristics of L. rufolineatus and compared them with the holotype ( Allen, 1995) and similar species, including L. boutton and L. dodecacanthoides (see Table 4 View TABLE 4 ). Our comparison highlighted distinct morphometric differences that assist in differentiating these species. For example, L. rufolineatus and the holotype from Allen (1995) both display XI dorsal spines, while L. boutton has X and L. dodecacanthoides has XII ( Koeda et al. 2014). Additionally, lateral line counts in L. rufolineatus from this study were between 47–49, consistent with Allen’s findings, but different from L. dodecacanthoides , which has 48. Other features, such as scale counts and gill raker numbers, also varied slightly among these species. These distinctions underscore the importance of thorough taxonomic analysis in identifying key traits for accurate species identification and contribute to conservation efforts by clarifying species boundaries. The morphometric measurements observed in this study largely aligned with those reported by Allen (1995) and Heemstra et al. (2022) for L. rufolineatus , although some minor variations, particularly in body depth and interorbital space, suggest potential regional or population-level differences within the species. Our findings highlight the need for further research on geographic variation in L. rufolineatus populations across its distribution range.

In recent years, molecular tools have proven invaluable in taxonomic studies, allowing for precise species identification and discovery ( Ribeiro et al. 2012). The COI gene has been particularly effective for species-level identification in fishes ( Ward et al. 2005; Bhattacharjee et al. 2012; Trivedi et al. 2014; Gold et al. 2015; Sala et al. 2023). In our study, DNA barcoding confirmed the identity of L. rufolineatus , showing high similarity with COI barcodes from GenBank. The intraspecific genetic distance between L. rufolineatus specimens in our study was 0.002, in line with Hebert et al. (2003), who observed intraspecific distances below 0.01 and interspecific distances above 0.022. Phylogenetic analysis revealed that the Andaman specimens of L. rufolineatus form a well-supported clade with other members of the same species, highlighting close relationships with other blue-lined snappers like L. quinquelineatus , L. bengalensis , and L. kasmira . Similar clustering was also observed in Andriyono et al. (2022), which examined L. rufolineatus and L. bengalensis in Indonesian waters, underscoring the phylogenetic cohesion within this group.

Historically, L. rufolineatus has often been misidentified in Indian taxonomic studies, partly due to incomplete descriptions in early literature, such as Day (1871, 1875), which failed to distinguish it adequately from L. boutton and L. bengalensis . Reviews by Talwar and Kacker (1984) and Kapoor et al. (2002) mistakenly included L. rufolineatus based on incorrect synonymy. Allen (1995) clarified its taxonomic status as a distinct species in the western central Pacific, a finding corroborated by Anderson et al. (1998), who documented it in the Maldives. L. rufolineatus did not appear in Indian snapper checklists ( Nair et al. 2014), underscoring ongoing uncertainties about its distribution. While it has been included in Tamil Nadu checklists (Joshy et al. 2016; Mogalekar et al. 2018), these records lack detailed taxonomic descriptions. Barman (2017) suggested that prior records in Indian waters may have misidentified L. rufolineatus as L. boutton , further highlighting the need for accurate redescription.

Several biodiversity assessments in the Andaman and Nicobar Islands, such as those by Roy and George (2010), Rajan and Sreeraj (2013), Ranjan et al. (2018), Patankar et al. (2018), and Rajan et al. (2021), did not document L. rufolineatus . This study represents the first confirmed report of L. rufolineatus in the Andaman and Nicobar Islands, India. By integrating DNA barcoding and detailed morphological analysis, this research provides a thorough taxonomic redescription of L. rufolineatus , resolving past misidentifications and improving our understanding of marine fish diversity in Indian waters. This study further contributes to biodiversity conservation efforts and enhances the accuracy of marine species cataloguing across the Indo-Pacific region.