First specimen-based Indonesian record of a rare scorpionfish, Scorpaenopsis obtusa (Actinopterygii: Perciformes: Scorpaenidae), from Alor Island

A single specimen of the shortsnout scorpionfish, Scorpaenopsis obtusa Randall et Eschmeyer, 2002 (Scorpaenidae), collected from the south coast of Ampera, Alor Barat Laut, Alor Island, Indonesia, at 5 m depth, represents the first voucher specimen-supported record of the species from Indonesian waters (previous records from Nusa Penida and northern Sulawesi having being based on underwater photographs). At 91.1 mm in standard length, the Alor specimen is the largest recorded individual of the species to date.


Results
Body wide anteriorly, progressively compressed posteriorly. Mouth large, oblique, positioned at angle of about 60° to horizontal axis of head and body. Posterior margin of maxilla extending beyond line from posterior margin of orbit to edge of retroarticular. Vomerine plate forming V-shaped patch, with rudimentary teeth. Palatine teeth absent. Nasal spine with 3 spinous points. Ascending process of premaxilla intruding into interorbital space, its posterior margin level with anterior margin of pupil. Median interorbital ridge absent. Interorbital ridges distinct; space between interorbital ridges shallow and broad, its width about half of orbit diameter. Preocular and supraocular spines small, directed upward. Postocular spine large, with 3 points, broadly joined to tympanic spine at base. Tympanic with 2 spinous points, located between postocular spines. Coronal spine absent. Occipital pit deep, its width greater than length. Parietal and nuchal spines about equal size, joined at base. Sphenotic with 2 small spines. Postorbital with 2 small spines. Pterotic spine simple, larger than supraocular spine. Upper posttemporal spine larger than lower spine. Space between parietal, nuchal, pterotic, and lower posttemporal spines with two small spines. Supracleithral spine asymmetric, with 3 and 2 pointed spines on left and right sides, respectively. Cleithral spine flattened, strongly pointed. Anterodorsal lacrimal spine present. Single small spines on middle and posterior end of lacrimal ridge. Anterior lacrimal spine directed anteriorly, its tip reaching dorsal margin of upper lip; two additional small points on posterior margin. Posterior lacrimal spine directed ventrally, larger than anterior spine, its tip not reaching dorsal margin of upper lip; an additional spine present on anterior margin; posterior lacrimal spine associated with short fimbriate flap. Lateral lacrimal spine present, its size approximately equal to anterodorsal lacrimal spine. Suborbital ridge with 3 spines. Suborbital pit present. Preopercle with 5 spines; uppermost spine largest, with supplemental preopercular spine on base; second spine sharp; third to fifth spines blunt. Upper opercular spine with 2 points; lower opercular spine simple, with median ridge.
Lateral surface of body covered with weak ctenoid scales, becoming cycloid ventrally. Exposed cycloid scales covering pectoral-fin base. Cycloid scales embedded in thin skin covering anteroventral surface of body. Body scales not extending onto fin rays or membranes, except basally on seven uppermost pectoral fin rays. Lateral line complete, first two scales with spine-like projection at end of sensory tube. No scales on head.
Numerous tiny papillae scattered on dorsal and lateral surfaces of head, including snout, interorbital space, outer margin of eye membrane, preopercle, and opercle. No papillae on occipital pit. Tentacle on upper posterior edge of low membranous tube associated with anterior nostril. Fleshy tentacle associated with posterior lacrimal spine. Several short, slender tentacles on lateral surface of maxilla. Broad, skin flap associated with each of third to fifth preopercular spines. Many small, round flaps on ventral surface of head and anteroventral surface of body.  Many slender tentacles associated with posterior margin of opercle, pored lateral scales scattered on lateral and dorsal surfaces of body, and pectoral and caudal fins.
Origin of first dorsal-fin spine above supracleithral spine. Posterior margin of opercular membrane level with posterior margin of third dorsal-fin spine base. Posterior tip of pectoral fin extending beyond third anal-fin spine base. Posterior tip of pelvic fin extending slightly beyond anus when depressed. Origin of last dorsal-fin spine just above origin of first anal-fin spine.
Color when fresh (Figs. 1, 3A). Head and body mottled dark reddish-brown to white. Dorsal fin whitish to reddish-brown, distinct black blotch on base of spinous portion between fourth and eighth spines. Pectoral fin outer surface pinkish-white, blackish basally, with blackish band near tip; inner surface orange, with broad black blotch basally on each of uppermost four and lowermost seven rays, black submarginal band (progressively less distinct on lower unbranched rays), axil and base of membrane of fifth to fourteenth rays white with small black spots. Pelvic fin black, with white distal margin. Anal fin dark reddish with numerous tiny spots and white posterior margin. Caudal fin whitish, with broad pinkish band.

Discussion
The characters of a single specimen of the genus Scorpaenopsis from Alor Island, Indonesia (Fig. 1), determined in this study, agreed well with the diagnostic characters of S. obtusa given by Randall and Eschmeyer (2001) and Motomura and Shinohara (2005), e.g., pectoral-fin rays 19; pored lateral-line scales 20; longitudinal scale series 38; gill rakers 13; body depth 2.2 times in SL; dorsal profile of anterior spinous portion of dorsal fin highly arched, giving a humpbacked appearance; head length 2.2 in SL; snout short and blunt 3.8 in HL; ascending process of premaxilla intruding into interorbital space; orbit diameter 4.4 in HL; nasal spine with 3 points; mouth oblique, forming an angle of about 60° to horizontal axis of head and body; postocular spine broadly joined to tympanic spine; occipital pit deep; suborbital pit deep; upper opercular spine doubled; first dorsal-fin spine length 1.5 in second dorsal-fin spine length; fourth dorsal-fin spine length 2.9 in HL; penultimate dorsal-fin spine length 1.2 in last dorsal-fin spine length; interorbital width at posterior end of preocular spine bases 4.1 in HL.
Scorpaenopsis obtusa was originally described by Randall and Eschmeyer (2001) on the basis of specimens from the Philippines (1 specimen, 79.0 mm SL) and Papua New Guinea (2, 36.5-49.7 mm SL). Motomura and Shinohara (2005) reassessed the diagnostic characters of S. obtusa given by Randall and Eschmeyer (2001), and reported the first specimen-based records of S. obtusa from Japan (1, 40.4 mm SL) and Australia (2, 34.8-37.8 mm SL), and second record from Papua New Guinea (25.6 mm SL). Subsequently, Motomura et al. (2011) reported the first record of the species from Taiwan (based on a single specimen, 47.7 mm SL). Later, S. obtusa was reported by Allen and Erdmann (2012: 234) from Indonesian waters (Nusa Penida and northern Sulawesi), based on underwater photographs. The presently reported specimen of S. obtusa from Alor Island, the ninth reported overall and largest known example of the species (91.1 mm SL), represents the first specimen-based record of the species from Indonesia (Fig. 2).
Scorpaenopsis obtusa, most similar to the western Indian Ocean humpback species Scorpaenopsis gibbosa (Bloch et Schneider, 1801) in inner pectoral fin surface color pattern (Eschmeyer and Randall 1975: 307, fig. 17c;Randall and Eschmeyer 2001;Motomura and Shinohara 2005: fig. 1), differs from the latter in four morphological characters: snout length, location of the premaxilla ascending process, and numbers of longitudinal scale rows and pectoral-fin rays (Randall and Eschmeyer 2001). Motomura and Shinohara (2005) confirmed the validity of these four characters, in addition to finding several additional diagnostic characters for S. obtusa, following a comparison between S. obtusa (6 specimens, 25.6-49.7 mm SL) and S. gibbosa (9 specimens, 37.4-99.4 mm SL), e.g., distance between ventral margin of orbit and suborbital ridge, interorbital width between posterior end of preocular spine bases, condition of posterior margin of maxilla, and caudal-fin color pattern in preserved specimens.
However, the color pattern of the pectoral fin inner surface on a fresh specimen photograph of the presently reported specimen of S. obtusa (Fig. 3A) differed slightly from the illustration given by Motomura and Shinohara (2005: fig. 1), i.e., small black spots scattered on the axil and extending to the base of the membranes between the fifth to fourteenth rays (presently reported study) (vs. restricted to axil), and a broad blotch basally on the upper and lower rays (vs. on upper rays only). These differences are regarded here as intraspecific variations.
Although Motomura and Shinohara (2005) noted that the distance between the ventral margin of the orbit (VMO) and suborbital ridge in S. obtusa and S. gibbosa did not reflect growth-related changes (see fig. 4), examination of the presently reported specimen indicated that the proportion measured in the presently reported specimen (91.1 mm SL; distance between VMO and suborbital ridge: 2.3 mm) is significantly larger than that of the largest one (49.7 mm SL; ca. 1.1 mm) examined by Motomura and Shinohara (2005: fig. 4). Thus, this morphometric character actually reflect the growth-related change. Notwithstanding, the distance between the VMO and suborbital ridge remains a useful character for separating similarly-sized individuals of S. obtusa and S. gibbosa.
The interorbital space between the posterior ends of the preocular spine bases in the presently reported specimen of S. obtusa was contained 4.1 times in HL, confirming the reliability of this diagnostic character for S. obtusa. However, because it is subject to growth-related changes (see Motomura and Shinohara 2005: fig. 5), the proportion is unlikely to be reliable for distinguishing between similarly-sized individuals of S. obtusa and S. gibbosa greater than 100 mm SL.
The presently reported specimen of S. obtusa also had the posterior margin of the maxilla extending well beyond a line from the orbit posterior margin and posteroventral tip of the retroarticular (Fig. 3B), as noted by Motomura and Shinohara (2005). In addition, the caudal-peduncle band on the presently reported specimen was almost lost following preservation (Fig. 3C), as was noted in smaller specimens of S. obtusa (<49.6 mm SL), which were uniformly white (see Motomura and Shinohara 2005: fig. 3).