Paracaesio brevidentata, White, William T. & Last, Peter R., 2012

White, William T. & Last, Peter R., 2012, Paracaesio brevidentata n. sp., a new snapper (Lutjanidae: Apsilinae) from Indonesia, Zootaxa 3418, pp. 51-60 : 52-59

Paracaesio brevidentata new species

Figs 1 , 2 a; Table 1

Holotype. MZB LM 788, 250 mm TL, 181 mm SL, Tanjung Luar fish landing site, Lombok, East Nusa Tenggara, Indonesia (08°45' S, 116°35' E), collected by W. White and Dharmadi, 23 Jan. 2011.

Diagnosis. A species of Paracaesio distinguished by a combination of the following characters: lack of canines or other enlarged teeth in upper or lower jaws; snout length 4.7 in head length; caudal fin deeply forked; pectoral-fin rays 18 or 19; tubular scales in lateral line 71–73; predorsal scales 25; scales between lateral line and middle of spinous dorsal fin 8; circumpeduncular scales 29; maxilla scaly; preopercle naked; coloration in life uniformly purplish brown, without dark bars; caudal fin dark red with brighter red margins, lobes not two toned; other fins paler reddish pink.

Description. Dorsal rays X, 10; anal rays III, 8; all dorsal and anal soft rays branched, last fully branched; pectoral rays 19 (left), 18 (right); pelvic rays I, 5, all soft rays branched; principal caudal-fin rays 9 + 8 (8 + 7 branched); procurrent caudal-fin rays 12 dorsally, 12 ventrally; tubed lateral-line scales 73 (left), 71 (right); predorsal scales 25; scale rows between lateral line and middle of spinous dorsal fin 8; scales between lateral line and origin of anal fin 16; circumpeduncular scales 29; gill rakers 30 (10+20); vertebrae 24 (10 precaudal + 14 caudal).

Body moderately deep, depth 2.86 in SL; body compressed, width 2.12 in depth; head length 3.46 in SL; snout short, 4.66 in head length; eye moderately large, orbit diameter 3.30 in head length; interorbital space strongly convex, its least width 2.76 in head length; suborbital depth narrow, 18.69 in head length; caudal peduncle depth 2.66 in head length.

Mouth small, maxilla reaching a vertical at anterior third of orbit (slightly posterior to anterior edge of pupil), upper jaw length 2.76 in head length; mouth oblique, terminal; no enlarged teeth in jaws, all teeth very small, inconspicuous, villiform. Nostrils slit-like, slightly above level of upper edge of pupil, positioned dorsolaterally; anterior nostril about two-thirds size of posterior nostril, its rim slightly more elevated than on posterior nostril; posterior flap of anterior nostril reaching posterior nostril; distance between nostrils subequal to length of anterior nostril; distance from rim of nostril to orbit 2.35 in eye diameter.

Opercle without spines; upper margin of preopercle almost linear, smooth, irregular; lower margin of preopercle moderately convex, smooth; angle of preopercle angular (damaged on one side).

Lateral line following contour of dorsal margin, reaching caudal fin slightly above its mid-base; most tubules distinct, simple, each directed slightly upward from lateral-line canal; scales on dorsum in very obvious horizontal rows; scales on nape almost extending forward to a vertical through anterior third of eye; diagonal supratemporal band of scales (2 rows anteriorly, 3 rows posteriorly) separated by a narrow naked gap from scales of nape; snout, chin, a broad region around orbit, and most of preopercle at angle naked; maxilla with small scales; premaxilla, dentary and gular membrane naked; isthmus scaly; naked dorsal surface of snout densely covered with minute subcircular pores, somewhat reticulated laterally on snout and around orbit; similar patches of pores on dentary and over posterior third of preoperculum; band of scales on cheek curving from corner of mouth and extending to postorbit, this band comprised of about 3 scale rows dorsally and about 7 rows ventrally; opercle scaly except for its posterior membrane; subopercle and interopercle scaly; no scales basally on either dorsal or anal fins; small scales basally on pectoral and pelvic fins.

Dorsal-fin origin over about eighth lateral-line scale; membranes of spinous portion of dorsal fin shallowly incised; spines slender, delicate; first spine about half length of second, and closely adjacent to it; second spine subequal in length to third, fourth spine slightly longer than third or fifth spines, 2.02 in head length; posteriormost spines slightly more widely separated than those anteriorly; soft rays nearly equal in length, anteriormost rays less strongly branched than those posteriorly; second ray longest, 3.09 in head; last ray about equal to length of penultimate soft ray. Anal-fin origin below base of second to third soft rays of dorsal fin; anal spines weak, slender; first spine almost two-thirds length of second; second and third spines subequal, second spine 3.27 in head length; second soft ray longest, 3.59 in head length; last soft ray only slightly shorter than other anal-fin rays. Bases of dorsal and anal fins partly concealed by scaly sheaths. Caudal fin very deeply forked; caudal concavity 1.15 in head length; upper caudal-fin lobe 2.42 in SL, 1.43 times head length. Pectoral fin narrow-based, elongate, subfalcate, extending almost to anal-fin origin, its length 2.89 in SL; its origin well forward of pelvic-fin origin, by about three-quarters of eye diameter; low on body, its base well below lower margin of eye. Pelvic fins very closely positioned, separated by a single, greatly enlarged, spear-shaped interpelvic scale, its length about a third of eye diameter; tip of pelvic fin almost reaching anus, fin length 1.70 in head length; spine very elongate, its length more than 80% of longest ray, much longer than longest anal-fin ray; fins partly recessible in a broad groove on belly. Anus widely separated from anal-fin base; distance from anus to anal-fin base subequal to eye diameter. Caudal peduncle moderately elongate, its length 1.37 in head length, its minimum height 1.94 in its length.

Colour. Holotype when fresh: body uniformly dark purplish brown, slightly paler ventrally; scales sharply defined, pale centrally with dark purplish brown margins; no dark bars or blotches on sides; naked part of snout paler than rest of head with a yellowish hue; dorsal, anal and paired fins pale reddish to pinkish; margins of dorsal fin elements dark dusky; caudal fin dark red with a brighter red posterior margin.

Distribution. Known only from the holotype collected from the Tanjung Luar fish market on the east coast of Lombok, southern Indonesia (08°45' S, 116°35' E). This specimen was caught by hand line over a deep reef near the eastern coast of Lombok. Exact depth unknown.

Etymology. The name brevidentata , an adjective, is derived from the Latin brevis (small) and dentata (toothed) in allusion to the small teeth of this species in comparison with its congeners. The English common name is Smalltooth Snapper.

Comparisons. Paracaesio brevidentata can be clearly separated from the other eight species of this genus by a combination of coloration, morphometrics, scalation, dentition and meristics.

Paracaesio brevidentata can be readily distinguished from P. caerulea ( Fig. 3 ), P. gonzalesi , P. kusakarii ( Fig. 4 ) and P. s t on e i in having much higher lateral-line scale counts (70–71 vs. 47–50) and a deeply forked caudal fin (vs. lunate or emarginate). A single specimen of P. caerulea ( Fig. 3 ) collected during this study at the same fish landing site as the holotype of P. brevidentata is the first confirmed record of this species from Indonesian waters. This specimen closely resembles the colour illustration of P. gonzalesi in Allen (1985) in having a bicoloured caudal fin (lower lobe yellow, upper lobe grey) and a broad oblique yellow stripe anteriorly over the lateral line. However, P. caerulea can be readily distinguished from P. gonzalesi in having the maxilla without scales vs. maxilla with scales, and body without dark bars vs. body with eight dark vertical bars ( Anderson et al., 1992). DNA barcoding analyses (www.boldsystems.org) using the CO1 gene revealed that P. caerulea sequences from Indonesia and Taiwan differed by about 3% from P. gonzalesi sequences from Australia, and grouped closest to P. kusakarii sequences from which they differed by about 2.7%.

Paracaesio brevidentata differs from P. paragrapsimodon in lacking prominent projecting canine teeth at anterior ends of both jaws and in having a scaly maxilla (vs. naked). It can be readily distinguished from P. waltervadi in possessing a deeply forked rather than lunate caudal fin and overall body coloration being purplish brown rather than blue. The new species is readily distinguishable from P. x a n t h u r a ( Fig. 5 ) in coloration with the latter species being mostly bluish with a broad yellow area on the upper sides. Paracaesio brevidentata is closest in general appearance to P. sordida ( Fig. 6 ) but differs in the following characters: maxilla scaly (vs. maxilla naked), preopercle naked (vs. mostly naked but with 1–3 rows of scales close to but separated from cheek scales, Fig. 2 b), pectoral-fin rays 18 or 19 (vs. 16 or usually 17), more scales between the lateral line and middle of the spinous dorsal fin (8 vs. 6–8). It also appears to have a shorter snout (snout length 4.66 vs. 3.85–4.12 in head length), shorter dorsal-fin soft rays with the penultimate soft ray not longer than the rays adjacent (penultimate soft ray 8.2 vs. 11.9–13.5% SL), shorter anal-fin elements (second anal-fin spine 8.8 vs. 9.5–10.2% SL, longest anal-fin soft ray 8.0 vs. 10.6–11.2% SL), maxilla narrower (maxilla width 3.1 vs. 3.5–3.9% SL), and the caudal peduncle slightly longer (21.0 vs. 19.0–20.1% SL).

Due to their preference for deepwater reef habitats, most members of this genus are rarely caught so ontogenetic and intraspecific variability is not well understood. Consequently, the extreme variability in eye size observed between a 205 mm SL specimen ( Fig. 5 a) and a 263 mm SL specimen ( Fig. 5 b) of P. xanthura is noteworthy.

Figures

FIGURE 1. Lateral view of Paracaesio brevidentata n. sp., holotype MZB LM 788, 181 mm SL, east Lombok, Indonesia.

FIGURE 2. Lateral view of head of: A. Paracaesio brevidentata n. sp., holotype (MZB LM 788, 181 mm SL); B. Paracaesio sordida (CSIRO H 7306 – 01, 211 mm SL).

FIGURE 3. Lateral view of Paracaesio caerulea, CSIRO H 7219 – 03, 168 mm SL, east Lombok, Indonesia.

FIGURE 4. Lateral view of Paracaesio kusakarii, CSIRO H 7219 – 04, 167 mm SL, east Lombok, Indonesia.

FIGURE 5. Lateral view of Paracaesio xanthura: A. Non-retained specimen, ~ 205 mm SL, Bali, Indonesia; B. CSIRO H 7308 – 01, 263 mm SL, east Lombok, Indonesia.

FIGURE 6. Lateral view of Paracaesio sordida, CSIRO H 7306 – 01, 211 mm SL, West Java, Indonesia.