Lutjanus octolineatus ( Cuvier 1828 )

Iwatsuki, Yukio, Al-Mamry, Juma M. & Heemstra, Phillip C., 2016, Validity of a blue stripe snapper, Lutjanus octolineatus (Cuvier 1828) and a related species, L. bengalensis (Bloch 1790) with a new species (Pisces; Lutjanidae) from the Arabian Sea, Zootaxa 4098 (3), pp. 511-528 : 513-519

Lutjanus octolineatus ( Cuvier 1828)

Proposed English name: Whitebelly snapper Figures 1 A‒B, 2A, & 3A; Table 1

Diacope octolineata Cuvier in Cuvier & Valenciennes 1828: 418 (in part, Type locality: Red Sea; Tahiti; Mauritius, Mascarenes, southwestern Indian Ocean; Ambon Island, Molucca Islands, Indonesia; Taxonomic identities of other syntype specimens are discussed under Remarks).

Diacope octovittata Valenciennes in Cuvier & Valenciennes 1830: 528 (Type locality: Mauritius, southwestern Indian Ocean).

Lutjanus bengalensis (non Bloch); Bleeker 1874: 27 ( Réunion); Kyushin et al. 1977: 68, unnumbered photograph (in part, Saya de Malha Bank); Allen & Talbot 1985: 21, pl. 1E, F (in part, Mauritius, and Amirante Islands [the Amirantes Islands are in Seychelles]); Allen 1985: 61, pl. XII, 45 (in part, northern Indian Ocean); Kuiter 1998: 106, unnumbered underwater photograph ( Maldives); Debelius 1999: 102 (in part, Mascarenes); Kuiter & Debelius 2006; 449, unnumbered photograph ( Maldives); Allen & Erdmann 2012: 445, unnumbered photograph ( Mauritius).

Lutjanus octovittatus ; Bleeker 1874: 35 ( Réunion).

Lectotype: MNHN 0000-A5446 (blue glass plate attached with one dried specimen at each for both sides; the designated lectotype with snout skin and the other without snout skin as paralectotype below), dried, 122 mm SL, Mauritius.

Paralectotype: MNHN 0000-A5446, dried, presumably ca. 119 mm SL (with snout region damaged on the side of blue glass plate attached with a label of MNHN 5446), other data same as the lectotype.

Non-type specimens (n =6): MNHN 0000-7046 (holotype of Diacope octovittata ), 137 mm SL, Mauritius, Mascarenes, southwestern Indian Ocean; NSMT 121733 ‒ 121734, 2 specimens, 154‒162 mm SL, Seychelles, Indian Ocean; HUMZ 90013, 209 mm SL, Saya de Malha Bank, Indian Ocean (10°47.0'S, 62°13.0'E); WAM 26780-001, 2 specimens, 67–72 mm SL, Mauritius, Indian Ocean.

Photographic voucher: SAIAB 81620, 136 mm SL, Nosy Be, Madagascar.

Diagnosis. A species of Lutjanus with the following combination of characters: Dorsal fin usually XII, 12 or 13; anal fin III, 8; pectoral fin 16 or 17; lateral-line scales 47‒50: horizontal scale rows above lateral line 8 or 9; scale rows on cheek 4‒6; subocular extension of cheek scales irregularly present in 1 or 2 row(s) anteriorly and 3 or 4 rows posteriorly, respectively below eye ( Fig. 2 A); total gill-rakers on first arch 8 or 9 + 18 or 19 = 26‒27; no blue stripe on upper part pf opercle, the third blue stripe on body (upper supracleithrum) beginning from dorsoposterior margin of opercle, extending to below the last soft dorsal-ray base.

Description. Meristic counts and proportional measurements as percentages of standard length (SL), plus two diagnostic characters in coloration and squamation of subocular extension for the lectotype, the paralectotype and non-type specimens of Lutjanus octolineatus are shown in Table 1.

Body oblong, greatest depth 2.8 – 3.1, head length 2.5‒2.8 in SL; snout length 3.1‒3.8, eye diameter 2.9‒3.7, interorbita1 width 4.3‒5.5, maxilla length 2.6‒2.7, and preorbital depth 5.6‒7.0 in head length; head relatively small with pointed snout; snout-forehead profile almost straight; pair of small rounded and somewhat ovate nostrils, anterior and posterior openings on each side of snout, with no flap on outer edge of anterior nostril; body scales rising obliquely above lateral line; body, opercle and preopercle with finely ctenoid scales; parietal, frontal, interorbital and rear edge of preopercle scaly; preopercular margin finely serrate (serrae increasing in size ventrally); sharp, flattened, flexible projection at middle of opercular margin, with blunt bony spine (mostly covered by scales) immediately above its base; margins of opercle, interopercle and subopercle smooth; preopercular notch and interopercular knob well developed; vomerine teeth in a crescentic band without median posterior extension (becoming a larger and randomly scattered group of 10‒13 similar canine teeth in a 209 mm SL specimen, 2 or 3 irregular rows of canines on both right and left branches of specimens 10−15 cm SL); tongue smooth without granular teeth; upper jaw with very short canine on each side anteriorly, and a smaller canine between it and symphysis; remaining lateral portion of upper jaw with a series of ~3‒10 smaller canines becoming embedded, lower jaw with ~5‒10 small canines on each side, becoming embedded with growth, 2 or 3 canines visible, but not the anterior canine tooth when mouth closed; dorsal-fin margin slightly incised, fourth or fifth spines longest, remaining spines gradually decreasing in length; profile of soft portion of dorsal-fin relatively low and weakly rounded; pectoral fins pointed, caudal fin emarginate.

TABLE 1. Counts and proportional measurements of Lutjanus octolineatus L. bengalensis and L. sapphirolineatus n. sp.

Lutjanus octolineatus Lutjanus bengalensis L. sapphirolineatus n. sp. ……continued on the next page TABLE 1. (Continued) Color in life, based on J.E. Randall’s photograph (10.8 cm SL, Mauritius; http://www.fishbase.org/photos/ PicturesSummary.php?StartRow=1&ID=1409&what=species&TotRec=6; 14 Dec. 2015) and G. Allen’s underwater photograph (12 cm TL, St. Joseph, Seychelles; http://www.fishbase.org/photos/ PicturesSummary.php?StartRow=0&ID=1409&what =species&TotRec=6; 14 Dec 2015): generally bright yellow on upper half, abruptly white (as indicated by the proposed common name), the belly coloration sometimes becoming reddish, often post mortem; upper side of body with four dark-edged blue stripes, uppermost extending from interorbital to below middle of spinous dorsal fin, second from upper rear edge of eye to below front part of soft portion dorsal-fin, third from behind upper rear edge of opercle (no stripe on upper part of opercle) to area just below base of the last soft dorsal-fin ray, and the lowest (fourth) from just above middle of maxilla across lower edge of eye, extending through middle preopercle and opercle to anterior third of caudal peduncle just below lateral line; median fins yellow, paler distally in soft portion of dorsal and anal fins; pectoral and pelvic fins whitish; iris yellow.

Color in alcohol: generally yellowish tan (including fins), with four brown or bluish stripes as noted above.

Distribution. Lutjanus octolineatus is confined on the basis of voucher specimens to the Western Indian Ocean: currently known from South Africa (Sodwana Bay and Cape Vidal), Mauritius, Seychelles, Saya de Malha Bank (southwest of the Chagos Archipelago) and Maldives ( Kuiter 1998). Photographic vouchers are from Mozambique, Madagascar and Réunion (E. Heemstra, pers. comm.).

Remarks. One of two syntypes (MNHN 0000-A 5446, 122 mm SL, Fig 1 A, explained above under Lectotype and Paralectotype) is designated as the lectotype of Diacope octolineata Cuvier in Cuvier & Valenciennes 1828, the other (without snout skin) becoming the paralectotype.

Allen & Talbot (1985) noted “We have examined a syntype of Diacope octolineata , the holotype of Mesoprion etaape (both MNHN 7973, 155 mm SL)” in Remarks in L. kasmira . The suggested syntypes of Diacope octolineata Cuvier are as follows: MNHN 0000-A5448 (as L. kasmira [ Forsskål 1775], 1, not 2 as erroneously listed in CAS database, C. Ferrara, R. Causse, G. Zora, pers. comm.), MNHN 0000-7971 (1, as L. kasmira ), MNHN 0000-7972 (1, as L. kasmira ), all from Mauritius, plus MNHN 0000-7973, the last, was subsequently used for the holotype of Mesoprion etaape Lesson 1831 from Tahiti. All these specimens have “dorsal-fin rays X, 14 and four clear stripes on the body in dried and preserved specimens”, here shown as diagnostic characters of L. kasmira among the blue-striped snapper complex ( Allen & Talbot 1985; p. 48, Table 3 as blue-striped complex). Unfortunately, one syntype from the Red Sea has been lost (C. Ferrara, R. Causse, G. Zora, pers. comm, MNHN database). Lastly, two other syntypes (MNHN 0000-A5547, 2 dried specimens, ~ 122‒133 mm SL, Indian Ocean, collected by Commerson) were identified as L. notatus ( Cuvier 1828) with six recognizable dark stripes on the body. Both have a narrow dark stripe from the lower pectoral-fin base (visible with transmitted illumination) to the lower caudal peduncle (see Table 3 of Allen & Talbot [1985]; L. bengalensis is without such a stripe) and dorsal-fin rays presumably XI, 12 for both (counted using dorsal-fin pterygiophores because of the missing fin are diagnostic characters of L. notatus among the blue-striped snapper complex ( Allen & Talbot 1985), and do not apply to L. quinquelineatus with X, 13–15 (usually 14).

Lutjanus octolineatus is distinguished from the closely related L. bengalensis by a dorsal-fin spine count of XII (vs. XI in L. bengalensis ). It has no blue stripe on the upper part of opercle, i.e. third stripe beginning from dorsoposterior margin of opercle (vs. blue stripe present on upper part of opercle in L. bengalensis , i.e. third stripe beginning before posterior margin of opercle). Furthermore, L. octolineatus has a subocular extension of 1 or 2 scale rows on the cheek to below anterior margin of eye, but L. bengalensis has no subocular extension. Hence, the two species are distinct, and are sympatric in the Western Indian Ocean. Subtly different niches of the two species might be observed with further research. Analysis of the mitochondrial cytochrome co-oxidase subunit 1 (CO1, 603 bp) strongly supports these as two distinct species, L. octolineatus and L. bengalensis , as well as distinguishing the other blue-striped snapper complex: L. kasmira , L. notatus , L. quinquelineatus , and L. sapphirolineatus n. sp. (See each species, pl. VI, A–C, pl. VIII, C–D, pl. VIII, E–F of Allen & Talbot [1985], and Fig. 4 , respectively, the last noted below).

Lutjanus sapphirolineatus n. sp., described below, can be differentiated by the following combination of characters: dorsal-fin XI, 13, and the third stripe from upper rear edge of eye, through upper part of opercle to upper part of caudal peduncle.

Lastly, Kyushin et al. (1977) included a color photograph (p. 70, 198 mm SL) that was identified as L. kasmira , as well as one of the true L. kasmira (p. 70, 206 mm SL). Both specimens were collected from the Chagos Archipelago. We identified the 198 mm SL specimen as L. octolineatus (missing from HUMZ), with 12 dorsal-fin spines, a diagnostic character. This presumably L. octolineatus specimen has a subtly different stripe pattern (usually there is no blue stripe on the upper opercle in specimens collected from South Africa, Mauritius, Réunion, Seychelles and Maldives), but shows a small, faint blue patch on the rear upper margin of the opercular membrane, which continues to the third blue stripe on the body ( Kyushin et al. 1977; p. 70, unnumbered figure, 198 mm SL).

Figures

FIGURE 1. Type specimens of Lutjanus octolineatus (A, B) and L. bengalensis (C): A. MNHN 0000 - A 5446 (no label attached with a blue glass plate), 122 mm SL, lectotype of Diacope octolineata, Mauritius, Mascarenes; B. MNHN 0000 - 7046 (holotype of Diacope octovittata), 137 mm SL, Mauritius, Mascarenes; C. ZMB 303, lectotype of Holocentrus bengalensis), 94 mm SL, Bengal, Bay of Bengal, eastern Indian Ocean.

FIGURE 2. Squamation of subocular extension of cheek scales: A. Lutjanus octolineatus MNHN 0000 - 7046, holotype of Diacope octovittata, 137 mm SL; B. L. bengalensis, ZMB 303 (lectotype of Holocentrus bengalensis), 94 mm SL; C. L. sapphirolineatus n. sp., MUFS 33724, holotype, 153 mm SL.

FIGURE 4. Lutjanus sapphirolineatus n. sp.: MUFS 33724, holotype, 153 mm SL, Muttrah, Oman.