Chelidoperca stella, Matsunuma, Mizuki & Motomura, Hiroyuki, 2016

Matsunuma, Mizuki & Motomura, Hiroyuki, 2016, Chelidoperca stella, a new species of perchlet (Perciformes: Serranidae) from the Andaman Sea, eastern Indian Ocean, Zootaxa 4092 (3), pp. 388-400 : 389-399

Chelidoperca stella sp. nov.

Figs. 1–7 ; Table 1

Holotype. USNM 389093, 57.4 mm SL, off Thailand, Andaman Sea (09°13′12″N, 97°51′00″E), 58–60 m depth, R/V Anton Bruun, bottom trawl, International Indian Ocean Expedition, cruise 1, sta. 20HYDRO, 23 Mar. 1963.

Paratypes. Four specimens of 51.7–61.8 mm SL. PMBC 27838, 61.8 mm SL, off Phuket, Thailand, Andaman Sea (obtained at Phuket local fish market), purse seine, 21 Mar. 2014; PMBC 27839, 51.7 mm SL, collected with holotype; USNM 389096, 56.1 mm SL, off Myanmar, Andaman Sea (15°07′48″N, 94°04′12″E), 66 m depth, R/V Anton Bruun, bottom trawl, International Indian Ocean Expedition, cruise 1, sta. 43, 1 Apr. 1963; USNM 389100, 53.7 mm SL, off South Andaman Island, Andaman and Nicobar Islands, India, Andaman Sea (11°52′01″N, 92°49′01″E), 66 m depth, R/V Anton Bruun, bottom trawl, International Indian Ocean Expedition, cruise 1, sta. 28A, 27 Mar. 1963.

Diagnosis. A species of Chelidoperca distinguished from other members of the genus by the following combination of characters: pectoral-fin rays 15; pored lateral-line scales 34 (or 35); scale rows in longitudinal series 35 (36–37); scale rows between lateral line and sixth dorsal-fin spine base 2.5; preopercular serrae 33 (37 in right side) (35–43); interopercular serrae 7 (8) (7–10); subopercular serrae 21 (19) (18–28); interorbital scales slightly extending anteriorly, almost reaching or slightly beyond level of mid-orbit; relatively wide interorbital region, its width 3.1–3.7 (mean 3.3) % SL; length of longest anal-fin soft ray moderate, 17.4–18.7 (18.1) % SL; pelvic fin white with several small yellow spots; no longitudinal dark bands on body sides.

Description. Characters given in the diagnosis are not repeated here. Morphometrics and meristics are given in Table 1 . Dorsal-fin rays X, 10; anal-fin rays III, 6; caudal fin truncate; upper lobe with pointed tip, slightly longer than lower lobe (based on paratypes), and 4 (2–3) unbranched and 8 branched segmented rays, lower lobe with 3 (or 2) unbranched and 7 branched segmented rays, 22 (19–20) total segmented rays. Scale rows above lateral line 3 (based on paratypes); scale rows below lateral line 9 (or 10); cheek scale rows 5; pre-dorsal-fin scale rows 7 or 8 (based on paratypes). First gill arch with 4 (or 5) rudiments and 2 rakers on upper limb and 6 (4–7) rudiments and 7 (or 6) rakers on lower limb; total rudiments and gill rakers 19 (17–19).

Body fusiform, slightly elongated; snout pointed, dorsal profile of snout forming angle of ca. 50° to horizontal axis of head and body; caudal peduncle relatively long. Orbit large, its dorsal margin included in dorsal contour of head. Mouth large, slightly oblique; posterior margin of maxilla extending beyond mid-orbit level but not reaching level of orbit posterior margin; maxilla expanded posteriorly, with a low lateral ridge; lower jaw slightly protruding beyond upper jaw when mouth closed. Upper jaw with a band of ca. 6 rows of small, sharp-tipped conical teeth, with ca. 15 enlarged canines on each side of symphysis; lower jaw with a band of ca. 5–6 rows of small, blunt conical teeth, with ca. 2 rows of enlarged canines within band; vomer with V-shaped band of ca. 6 rows of small conical teeth, with several large canines posteriorly; palatine with a relatively long band of 2–4 rows of small, sharp-tipped conical teeth. Anterior nostrils situated at middle of snout, with small rounded flap rising from posterior rim; posterior nostril an elliptical opening at anterior border of orbit. Opercle with two flat, prominent spines, upper spine slightly longer than lower ( Fig. 1 B); angle of upper and lower spines ca. 40°; posttemporal with a small bony crest including 2 (2–4) serrae tips at beginning of lateral line.

Holotype Paratype Paratype Paratype Paratype ......continued on the next page ......continued on the next page Holotype Paratype Paratype Paratype Paratype upper + lower = total rakers

anal-fin, D: dorsal fin, LL: lateral line, P1: pectoral fin, P2: pelvic fin, S: spine Body with ctenoid scales; lateral line slightly arched over pectoral fin before gradually descending, terminating at caudal-fin base. Uppermost row of body scales along dorsal-fin base always about half size of lower body scales. Small cycloid basal scales on caudal and pectoral fin bases, not extending onto fins; basal scales absent on dorsal, anal and pelvic fin bases. Head generally with ctenoid scales but absent on snout and maxilla; ventral surface of the angular entirely covered with cycloid scales with two rows of cycloid scales extending anteriorly onto the dentary; interopercle, subopercle and opercle with ctenoid scales; interorbital region with cycloid scales. A pair of interorbital canals with numerous small pores running along outer margin of interorbital region, diverging outward anteriorly, and reaching between anterior and posterior nasal pores; pores of interorbital canal forming ca. 4 rows (a pair of ca. 2 rows on each side; Fig. 2 ). Dentary with four pairs of sensory pores; anteriormost pores simple, situated each side of dentary symphysis; two pores situated on each side of angular, covered with thin skin, possessing one or two minute pores; posteriormost pores slit-like, situated anteriorly on the angular ( Fig. 3 ).

Dorsal-fin origin above pectoral-fin base, fourth spine longest, eighth or ninth spine shortest (based on paratypes); all soft rays branched, subequal in length, ninth longest. Anal-fin origin below second dorsal-fin soft ray base, third spine longest; all soft rays branched, fifth longest. Pectoral fin with uppermost three (two) rays unbranched, remaining rays branched, eighth or ninth longest, its posterior tip reaching level of anal-fin origin (based on paratypes). Pelvic-fin origin below pectoral-fin base; spine covered with skin; all soft rays branched, second longest, elongate, expanded distally, its tip reaching anus when depressed.

Color of fresh specimen. Based on a color photograph of a paratype (PMBC 27838) taken prior to fixation and preservation ( Fig. 4 ) (most body scales lost but skin coloration retained). Head and body pinkish, whitish ventrally. Ventral margin of orbit rim yellowish. Dorsal-fin membrane semi-translucent with numerous small yellow spots (ca. 30–50 % of iris diameter). Anal-fin membrane white; distal margin broadly yellow (membranes between each ray mostly broken—coloration determined from remaining membrane). Pelvic-fin membrane white with a transverse row of three small yellow spots (about half of iris diameter) on inner portion. Caudal fin dusky yellow.

Color of preserved specimens. Head and body uniformly creamy white or pale brown, all fin membranes translucent, without any dark markings ( Fig. 5 ).

Etymology. The specific name, stella , a feminine Latin noun meaning star, alludes to the species being characterized by several yellow spots on the pelvic fin.

Distribution. The new species is currently known only from the Andaman Sea in the eastern Indian Ocean. Among the species of Chelidoperca , only C. margaritifera has been previously recorded from the Andaman Sea (Satapoomin 2011). However, the new species and new record of C. pleurospilus (based on PMBC 10988, 113.1 mm SL) noted in this study bring to three the number of Andaman Sea species of Chelidoperca . Sampling data accompanying the type series indicated capture by bottom trawl or purse seine at depths of 58– 66 m.

Comparisons. Chelidoperca stella is characterized by several yellow spots on the posterior portion of the pelvic fin ( Fig. 4 ), similar markings being absent on all congeners (Fourmanoir 1982; Yamada et al. 2007; Bineesh et al. 2013,. 2014; Williams & Carpenter 2015; this study). Chelidoperca stella is also distinguishable from C. investigatoris , C. occipitalis , and C. pleurospilus by the absence of longitudinal dark bands on the sides of the body (vs. a straight or broken longitudinal dark band present in the latter three species) (Günther 1880; Alcock 1890, 1894; Kotthaus 1973; Bineesh et al. 2013; this study). Chelidoperca maculicauda and C. lecromi are characterized by a dark spot on the upper portion of the caudal fin (Bineesh et al. 2013) and several longitudinal rows of white spots on the sides of the body (Fourmanoir 1982), respectively, such markings being absent in C. stella .

Meristic characters also distinguish C. stella ; from C. hirudinacea by 15 pectoral-fin rays [vs. 16–17 (mode 16) in the latter]; and from C. hirudinacea , C. lecromi , and C. pleurospilus by 2.5 scale rows between the lateral line and the sixth dorsal-fin spine base (vs. 3.5 in the latter three species) (this study). Chelidoperca stella is also characterized by lower numbers of pored lateral-line scales (34 or 35) and scale rows in the longitudinal series (35– 37) (vs. 40–45 in all valid congeners and 44–47 in C. hirudinacea , C. margaritifera , C. lecromi , and C. pleurospilus , respectively) (Bineesh et al. 2013, 2014; Williams & Carpenter 2015; this study).

The number of serrae on some bones of the head is also useful for the identification of the species of Chelidoperca , as stated by Akazaki (1972). Although the examined specimens of C. stella were of relatively small body size (51.7–61.8 mm SL), serrae on the preopercle, interopercle and subopercle margins were well developed. Chelidoperca stella can be clearly distinguished from C. hirudinacea and C. pleurospilus by the greater number of preopercular serrae 33–43 (vs. 17–28 and 13–22 in C. hirudinacea and C. pleurospilus , respectively, in specimens of 50–90 mm SL) and interopercular serrae 7–10 (vs. 3–6 and 4–6 in C. hirudinaceus and C. pleurospilus , respectively, in specimens of 50–70 mm SL) ( Fig. 6 A–B). Chelidoperca stella also differs from the above two species plus C. margaritifera by having a more subopercle serrae 19–28 (vs. 4–15, 5–15 and 4–22 in C. hirudinacea , C. pleurospilus , and C. margaritifera , respectively, in all stages) ( Fig. 6 C).

Morphometric measurements showed C. stella to resemble C. margaritifera in having a relatively wide interorbital region [3.1–3.7 (mean 3.3) and 3.6–4.7 (4.1) % SL, respectively], compared with C. hirudinacea , C. pleurospilus , and C. lecromi , [2.7–3.4 (3.0), 2.1–2.9 (2.5) and 2.4–3.0 (2.7) % SL, respectively] ( Fig. 7 A). However, C. stella can be distinguished from C. margaritifera by the slightly shorter longest anal-fin soft ray [17.4–18.7 (18.1) % SL vs. 22.6–26.4 (24.4) % SL in the latter] ( Fig. 7 B).

The extent of the interorbital scales, previously regarded as diagnostic within Chelidoperca (see Akazaki 1972), remains a useful character. In C. stella , the anteriormost interorbital scales almost reach, or extend slightly beyond, the level of the mid-orbit ( Fig. 2 ), but extend far beyond the level of the mid-orbit, reaching the level of the orbit anterior margin, in C. hirudinacea and C. investigatoris (Akazaki 1972; Bineesh et al. 2014: fig. 3; this study), and that of the posterior nasal pores in C. lecromi (Fourmanoir 1982; this study).

Remarks. Chelidoperca stella is closely similar to Chelidoperca sp. 1, briefly described by Sainsbury et al. (1985: 124) from off northwestern Australia, in having a lower number of pored lateral-line scales (35 or 36 in the latter) and the pelvic fin white with yellow flecks. Although specimens of Chelidoperca sp. 1 were unavailable for this study, that species may be conspecific with C. stella , although differing from the specimens described herein in having 2 or 3 series of iridescent pale blue spots along the flank (Sainsbury et al. 1985) (absent in C. stella ).

As the above mentioned, C. pleurospilus has not previously been recorded from the Andaman Sea (Satapoomin 2011).Therefore, a single specimen (PMBC 10988, 113.1 mm SL) examined in this study represented the first record for the species from the Andaman Sea.

Figures

FIGURE 1. Semi-schematic drawings of head spines in Chelidoperca stella. A: posttemporal serrae; B: opercular serrae; C: preopercular serrae; D: interopercular serrae; and E: subopercular serrae. A and B – E based on paratype (PMBC 27839, 51.7 mm SL) and holotype (USNM 389093, 57.4 mm SL), respectively. C and D based on right side (reversed). Bars indicate 1 mm.

FIGURE 2. Dorsal view of head of Chelidoperca stella, USNM 389096, paratype, 56.1 mm SL, showing conditions of interorbital scales and sensory pores. AN and PN indicate anterior and posterior nasal pores, respectively. Arrow heads indicate interorbital scales. Bar indicates 2 mm.

FIGURE 3. Dentary of Chelidoperca stella, USNM 389096, paratype, 56.1 mm SL, showing conditions of scales and sensory pores. Arrow heads indicate sensory pores. Bar indicates 2 mm.

FIGURE 4. Fresh specimen of Chelidoperca stella, PMBC 27838, paratype, 61.8 mm SL, off Phuket, Thailand, Andaman Sea.

FIGURE 5. Preserved specimens of Chelidoperca stella. A: USNM 389093, holotype, 57.4 mm SL, off Thailand, Andaman Sea; B: USNM 389096, paratype, 56.1 mm SL, off Myanmar, Andaman Sea; and C: PMBC 27839, 51.7 mm SL, off Thailand, Andaman Sea.

FIGURE 6. Relationships between numbers of preopercular serrae (A), interopercular serrae (B), and subopercular serrae (C) to standard length (mm) in Chelidoperca stella (red stars), C. hirudinacea (orange squares), C. lecromi (green diamonds), C. margaritifera (blue crosses), C. pleurospilus (gray downward triangles), and C. santosi (purple upward triangles).

FIGURE 7. Relationships between interorbital width (A) and longest anal-fin soft ray length (B) to standard length (mm) in Chelidoperca stella (red stars), C. hirudinacea (orange squares), C. lecromi (green diamonds), C. margaritifera (blue crosses), C. pleurospilus (gray downward triangles), and C. santosi (purple upward triangles).

Tables

TABLE 1. Meristics and morphometrics, expressed as percentages of standard length, of Chelidoperca stella.

Standardlength(mm)	USNM 389093 57.4	PMBC 27838 61.8	PMBC 27839 51.7	USNM 389096 56.1	USNM 389100 53.7
Dorsal-fin rays Anal-fin rays	X, 10 III, 6	X, 10 III, 6	X, 10 III, 6	X, 10 III, 6	X, 10 III, 6
Pectoral-finrays(bothsides)	15	15	15	15	15
PoredLLscales Scale rows in longitudinal series	34 35	— 37	— —	35 36	34 36
Scale rows above LL ScalerowsbelowLL	— 9	3 9	— —	3 9	3 10
Scale rows between LL and 6th DS base	2.5	2.5	—	2.5	2.5
Cheekscalerows Pre-dorsal-finscalerows	5 —	5 7	— —	— 8	5 8
Preopercle serrae (right side) Interopercle serrae	33 (37) 7 (8)	43 (—) 10 (7)	36 (35) 9 (8)	39 (42) — (—)	38 (40) 9 (7)
Subopercle serrae Posttemporal serrae	21 (19) — (—)	26 (24) 2 (3)	28 (22) 4 (3)	22 (—) 3 (—)	18 (21) 2 (2)
Gill rakers*	6 + 13 =19	6 + 11 = 17	7 + 11 = 18	6 + 13 = 19	6 + 12 = 18