Pteroidichthys amboinensis Bleeker, 1856

Motomura, Hiroyuki & Kanade, Yuka, 2015, Review of the scorpionfish genus Pteroidichthys (Scorpaenidae), with descriptions of two new species, Zootaxa 4057 (4), pp. 490-510 : 499-503

Pteroidichthys amboinensis Bleeker, 1856

[English name: Ambon Scorpionfish; Japanese name: Tsunokasago] ( Figures 2 A–C, 3C, 4–6; Table 3)

Pteroidichthys amboinensis Bleeker, 1856: 34 (type locality: Ambon, Moluccas Islands or Manado, Sulawesi, Indonesia). Rhinopias godfreyi Whitley, 1954: 60 , pl. 3, fig. 2 (type locality: Exmouth Gulf, Western Australia, Australia).

Lectotype. RMNH.PISC 5873, 56.0 mm SL, Ambon, Moluccas Islands or Manado, Sulawesi, Indonesia.

Paralectotype. RMNH.PISC 5873, lacking anterior half of head, 37.6 mm from posterior margin of orbit to hypural plate, Ambon, Moluccas Is. or Manado, Sulawesi, Indonesia.

Other material examined. 22 specimens, 14.4–78.7 mm SL. Japan: BSKU 42534, 37.3 mm SL, Tosa Bay, Shikoku, 33°26–28ʹN, 133°30–34ʹE, 27–29.5 m, RV Toyohata-maru, 5 Feb. 1986; BSKU 45325, 45.5 mm SL, Tosa Bay, Shikoku, 33°26–28ʹN, 133°31–33ʹE, 29.5–30 m, RV Toyohata-maru, 7 Nov. 1988; BSKU 62267, 60.6 mm SL, BSKU 62268, 47.8 mm SL, outside Karyougou Fishing Port, Nahari, Kochi, Shikoku, 17 m, W. Hiramatsu, 17 Jan. 2003; IOP (at KPM) 2058, 33.8 mm SL, Futo, east coast of Izu Peninsula, 14 m, M. Yanagita, 10 Oct. 1990; IORD 78–172, 57.1 mm SL, Amitori Bay, Iriomote I., Yaeyama Is, 40 m, H. Yokochi, 15 July 1978 (kept in aquarium until 13 Mar. 1979); KPM-NI 16145, 14.4 mm SL, Aka Island, Kerama Is., 15 m, T. Yoshimura, 30 July 2005; KSHS (at NSMT) 24500, 31.3 mm SL, Morote Bay, Ehime, Shikoku, 7 m, W. Hiramatsu, 14 July 1985; MUFS 21921, 36.8 mm SL, off Senbonhama, Numazu, Suruga Bay, 20–30 m, D. Kanbayashi, 5 Sept. 2002 (kept at aquarium until 12 Sept. 2002). Vietnam: NSMT-P 70499, 70.2 mm SL, fish landing port at Nha Trang. Indonesia: BPBM 36765, 43.0 mm SL, east end of Maumere Bay, Flores, 7–9 m, B. Russell, 7 Nov. 1991; KPM- NI 13992, 44.3 mm SL, south of Kalimantan. Australia: AMS IB. 2977, holotype of Rhinopias godfreyi Whitley , 47.1 mm SL, Exmouth Gulf, Western Australia, CSIRO Fisheries, 3 Aug. 1952; CSIRO CA 4021, 66. 5 mm SL, northeast of Cape Lambert, Western Australia, 20°08ʹS, 117°29ʹE, 38 m, 18 Oct. 1983; CSIRO H 6799-01, 35.3 mm SL, east of Shelburne Bay, Queensland, 11°49′S, 143°40′E, 23 m, D. Gledhill, 1 Oct. 2004; CSIRO H 6800-01, 58.4 mm SL, north of Bowling Green Bay, Queensland, 19°07′S, 147°11′E, 22 m, D. Gledhill, 2 Dec. 2003; QM I. 23937, 2, 34.3–44.2 mm SL, off Cairns, Queensland, 16°43ʹS, 146°13ʹE, 42.5 m, 26 Jan. 1981; QM I. 30608, 78.7 mm SL, Cockburn Reef, Queensland, 11°46ʹS, 143°34ʹE, 23 m, 18 Dec. 1995. Papua New Guinea: BPBM 36913, 24.3 mm SL, Observation Point, Normanby I., d’Entrecasteaux Is., 09°44ʹS, 150°44ʹE, 10 m, J. Earle, 7 Dec. 1995. Fiji: MNHN 2008-2542, 38.6 mm SL, 17°46′59ʺS, 177°12′00″E, 32 m, RV Alis, 21 Oct. 1998. Locality unknown: BPBM 37608, 60.9 mm SL, possibly Indonesia or Philippines, obtained by S. Michael from an aquarium fish dealer in Lincoln, Nebraska in 1994–1995.

Diagnosis. A species of Pteroidichthys with the following combination of characters: anal fin with 2 spines and 6 soft rays; dorsal-fin spines flexible (spines bend easily under slight pressure); snout relatively short, its length 12.3–17.0% (mean 14.3%) of SL, shorter than postorbital length; posterior margin of maxilla reaching to or extending beyond vertical through middle of pupil; distance between tips of lateral lacrimal and first suborbital spines shorter than or subequal to that between tips of first and second suborbital spines; supplemental preopercular spine absent; tentacles on supraocular and posterior lacrimal spines well developed, their lengths greater than orbit diameter; numerous tentacles on trunk and fins; lateral lacrimal and suborbital spines poorly developed, indistinct, usually tiny spines and often bony protuberances without pointed tips; no distinct black blotch on soft-rayed portion of dorsal fin.

Distribution. Known from the Indo-West Pacific where the species was recorded from southern Japan (except for the Ryukyu Islands), Vietnam, Indonesia, Papua New Guinea, Fiji, and Australia (Western Australia and Queensland) (this study; Fig. 6 ), and Taiwan ( Chen & Liu 1984), India (Rama Rao 1980), and the Red Sea ( Dor 1984). The species has been collected from sandy bottoms in depths of 7– 43 m.

Remarks. Pteroidichthys amboinensis was originally described by Bleeker (1856) from two specimens (74 and 82 mm total length) from Amboina (= Ambon) and Manado, Indonesia. Subsequently, Bleeker (1876: table 1, fig. 5) published a drawing of P. amboinensis that was reproduced by Burgess & Springer (1989: scorp. tab. 4, fig. 1). The illustrated fish was measured as 79.0 mm TL (59.3 mm SL). The two syntypes from Ambon and Manado exist at the fish collection of RMNH and have been registered as RMNH.PISC 5873, although they were in very poor condition. One specimen was measured as 56.0 mm SL but the other lacked the anterior half of the head (37.6 mm from the posterior margin of the orbit to the hypural plate). Bleeker’s habit was to reproduce figures at life size, but we could not determine which specimen was drawn for the figure. Thus, we herein designate the 56.0 mm specimen as the lectotype of P. amboinensis ( Fig. 2 A), the other specimen, which lacks the anterior half of the head, becoming a paralectotype.

Lectotype of Holotype of Non-types of

Pteroidichthys Rhinopias Pteroidichthys

amboinensis godfreyi amboinensis

RMNH.PISC 5873 AMS IB 2977 n = 21

Standard length (mm) 56.0 47.1 14.4–78.7

Meristics Modes Dorsal-fin rays XII, 9 XII, 9 XII, 9 XII, 9 ......continued on the next page Lectotype of Holotype of Non-types of

Pteroidichthys Rhinopias Pteroidichthys

amboinensis godfreyi amboinensis

RMNH.PISC 5873 AMS IB 2977 n = 21 Rhinopias godfreyi was originally described by Whitley (1954) on the basis of a single specimen (AMS IB. 2977, 47.1 mm SL; Fig. 2 B) from Exmouth Gulf, Western Australia. Eschmeyer et al. (1973) redescribed the holotype, but deferred a decision on whether the species was valid or a synonym of P. amboinensis to the future, when more specimens were available to study. Subsequently, Allen & Cross (1989), Hutchins (2001), and Allen et al. (2007) regarded it as a valid species, Pteroidichthys godfreyi , and Mandrytsa (2001) treated it as a valid species of Rhinopias , although they did not indicate any differences between P. (or R.) godfreyi and P. a m bo i ne n s i s. Examination of the holotype of R. godfreyi , the lectotype of P. amboinensis , and a large number of specimens considered here as P. amboinensis (see Table 3) showed them to be identical in sharing characters given in the Diagnosis of P. amboinensis . Accordingly, R. godfreyi is regarded here as a junior synonym of P. amboinensis .

Examination of a series of life stages between 14.4 and 78.7 mm SL recognized the following morphological changes with growth. All pelvic-fin soft rays of the 14.4 mm SL specimen were unbranched. The third to fifth pelvic-fin soft rays of the 24.3 mm SL specimen were unbranched (first and second rays branched), the third ray becoming branched in the 31.3 mm SL specimen (fourth and fifth rays unbranched), the fourth ray becoming branched in the 37.3 mm SL specimen (fifth ray unbranched), and then all rays branched in specimens exceeding 44.3 mm SL (plus 33.8 mm SL and 34.3 mm SL specimens). Although an increase in the number of pectoral-fin rays becoming branched with growth has been well known in some scorpionfishes (e.g., genus Scorpaena, Motomura et al. 2005b , c, 2007, 2011b), such an ontogenetic change in the pelvic-fin rays found in P. amboinensis during this study has not previously been reported in the family Scorpaenidae .

The lateral surface of the lacrimal of all specimens less than 57.1 mm SL does not have a distinct spine (usually forming only a ridge or bony protuberance), whereas that of all specimens exceeding 60.9 mm SL has a single pointed spine. The presence or absence of the lateral lacrimal spine has been recognized as one of the most important taxonomic characters for distinguishing some species of scorpionfishes ( Motomura et al. 2005b, 2009, 2014), indicating that the spine is not usually variable within a species. However, the lateral lacrimal spine in P. amboinensis appears to develop when an individual attains 60 mm SL. The nasal spine of P. amboinensis is well exposed distally in juveniles, becoming embedded by skin with growth.

A specimen (BPBM 36765, 43.0 mm SL) from Indonesia has well developed eggs, each about 0.5 mm in diameter.

The dorsal-fin spines of P. amboinensis are relatively soft, being bent easily under slight pressure. This character is unique among species of Pteroidichthys , which usually have rigid spines typical of scorpionfishes in general. Tentacles on the supraocular and posterior lacrimal spines are well developed, their lengths being greater than the orbit diameter (supraocular tentacle length 20.9–51.8% of SL; Table 3) and numerous tentacles are present on the lateral surface of the trunk and the fins in P. amboinensis , whereas the tentacles on the supraocular and posterior lacrimal spines are poorly developed, their lengths are usually less than the orbit diameter (2.6–8.5% of SL in P. acutus , 6.4–9.1% in P. caussei , and 3.3–24.1% in P. noronhai ; Tables 1–2, 4 ) and few tentacles on the trunk and fins in other congeners. The lateral lacrimal and suborbital spines in P. amboinensis are poorly developed compared with the well-developed spines in other congeners.

The body width of P. amboinensis is remarkably narrow (10.2–19.4% of SL, mean 16.0% of SL), differing from P. noronhai , which has a relatively wider body width (15.6–24.4%, 21.0%) ( Fig. 4 A). In addition, most fin rays of P. amboinensis tend to be longer than those of other congeners ( Tables 1–4); comparisons of lengths of longest dorsal- and anal-fin soft rays, and caudal and pectoral fins, among four species are given in Fig. 5 .

Pteroidichthys amboinensis and P. caussei can be easily distinguished from P. acutus and P. noronhai by having two spines and six soft rays in the anal fin (vs. three spines and five soft rays in the latter two species) and lacking a supplemental preopercular spine (vs. spine present). In addition to the above-mentioned differences, P. amboinensis further differs from P. caussei in the absence of a distinct black blotch on the soft-rayed portion of the dorsal fin (vs. black blotch on membranes between last spine and fourth soft ray of dorsal fin in P. caussei ).

Collection data for P. amboinensis showed that it was collected from relatively shallow waters in depths of 7– 43 m, whereas other congeners were collected from deeper waters. Pteroidichthys acutus , P. noronhai , and P. caussei were recorded from 73–400, 52–215, and 68–122 m respectively.

The number of scale rows in the longitudinal series is an important character to separate scorpionfish species. However, although scales of specimens of P. amboinensis are well retained (because most specimens were collected by hand nets in shallow water), most scales of other congeners were lost due to being trawled from deeper water. Therefore, the numbers of scale rows in the longitudinal series provided for P. acutus (34–36), P. caussei (34), and P. noronhai (36–39) may be inconclusive, but that of P. amboinensis (38–43) is possibly higher than the others ( Tables 1–4).

Figures

FIGURE 2. Species of Pteroidichthys with two spines and six soft rays in the anal fin. A: P. amboinensis, RMNH. PISC 5873, lectotype, 56.0 mm SL; B: P. amboinensis, AMS IB. 2977, holotype of Rhinopias godfreyi, 47.1 mm SL; C: P. amboinensis, KPM-NI 13992, 44.3 mm SL; D: P. c au s s e i n. sp., MNHN 2005 - 2607, holotype, 39.6 mm SL; E: P. c au s s e i n. sp., BPBM 33821, paratype, 40.0 mm SL; F: P. caussei n. sp., MNHN 2010 - 0931, paratype, 22.0 mm SL.

FIGURE 4. Relationships of (A) body width to standard length and (B) snout length divided by postorbital length to standard length in Pteroidichthys noronhai (closed circles), P. acutus n. sp. (open stars), P. amboinensis (open triangles), and P. caussei n. sp. (open diamonds).

FIGURE 5. Comparisons of lengths of (A) longest dorsal-fin soft ray, (B) caudal fin, (C) pectoral fin, and (D) longest anal-fin soft ray with standard length in Pteroidichthys noronhai (closed circles), P. acutus n. sp. (open stars), P. amboinensis (open triangles), and P. caussei n. sp. (open diamonds).

FIGURE 6. Distributional records of species of Pteroidichthys on the basis of specimens examined during this study. Circles, P. noronhai; stars, P. acutus n. sp.; triangles, P. amboinensis; diamonds, P. caussei n. sp. Literature records from the Indian Ocean (P. noronhai in the Saya de Malha Bank; P. amboinensis in the Red Sea and India) were omitted.