Rhabdamia gracilis ( Bleeker 1856 )

Yoshida, Tomohiro & Motomura, Hiroyuki, 2018, Redescription of the Indo-West Pacific cardinalfishes (Perciformes: Apogonidae) Rhabdamia spilota Allen & Kuiter 1994 and R. gracilis (Bleeker 1856), Zootaxa 4377 (2), pp. 178-190 : 185-188

Rhabdamia gracilis ( Bleeker 1856)

[New English name: Translucent Cardinalfish; Japanese name: Sukashi-tenjikudai] Figures 5–8 ; Table 1

Apogonichthys gracilis Bleeker 1856: 371 (type locality: Ternate, Moluccas, Indonesia).

Rhabdamia gracilis Hirata et al. 2001: 51 , unnumbered figs. (Ohtsuki, Kochi, Japan); Mabuchi 2001: 185, unnumbered fig. (Iburi, Kochi, Japan); Yoshida & Motomura 2013: 136, unnumbered figs. (Take-shima island, Kagoshima, Japan).

Lectotype. RMNH.PISC 5609, 30.7 mm SL, Ternate, Moluccas, Indonesia.

Paralectotypes RMNH. PISC 34135 , 36 specimens, 27.9–46.5 mm SL, same data as lectotype.

Non-type specimens. 61 specimens, 28.3–59.3 mm SL. SEYCHELLES: ANSP 164501 , 43.7 mm SL, Beacon Island , 04°37′S, 55°31′E, 12–15 m depth, J. Böhlke et al., 3 February 1964 ; ANSP 164505, 2, 38.5–41.3 mm SL, Beau Vallon Bay, Mahé, 04°37′S, 55°25′E, 6–7.5 m, J. Böhlke et al., 15 March 1964 ; ANSP 164538 , 43.5 mm SL, southwest of Ressource Island, Saint Joseph Islands, Amirante Islands , 05°26′S, 53°22′E, 24–30 m, J. Böhlke et al., 7 March 1964 ; BPBM 35775, 12, 40.6–44.9 mm SL, D Arros, Amirante Islands , 05°29′S, 53°18′E, 50–55 m, R/V Tyro , 28 December 1992 . MALDIVES: BPBM 34738 , 40.8 mm SL, Haleem’s Island , Male Atoll, spear, 18 m, J. Randall, 20 October 1988 . THAILAND: KAUM –I. 33319, 44.2 mm SL , KAUM –I. 33320, 44.6 mm SL, Kuraburi Fishing Port, Amphoe Kuraburi , Ranong Province, 09°22′N, 98°23′E, trawl . AUSTRALIA: AMS I. 26941-004, 7, 28.9–41.8 mm SL, west northwest of Dampier , WA, 21°58′S, 115°57′E, RV Soela ; CSIRO B 2011, 2, 43.3–44.0 mm SL, northwest of Admiralty Gulf , 12°16′S, 124°03′E, 82 m, 16 July 1980 ; WAM P. 25371-012, 5, 35.7–46.4 mm SL, off Tantabiddi, WA, spear, 15–18 m, G. Allen, 30 June 1975. MALAYSIA: BPBM 21943, 6, 41.8–45.8 mm SL, Pulau Tioman Island , spear, 8 m, J. Randall, 3 August 1977 . JAPAN: NSMT-P 100281, 59.3 mm SL , NSMT-P 100926, 58.9 mm SL, Iburi, Tosashimizu, Kochi, set net, M. Nakae, 24 July 2009 ; KAUM –I. 7033, 57.4 mm SL, east of Sakinoyama, Kataura, Kasasa , Minamisatsuma , Kagoshima, 31°25′44″N, 130°11′49″E, set net, 27 m, M. Itou, 9 June 2007 ; KAUM –I. 7823, 28.3 mm SL, off Kouzaki-yama, Kataura, Kasasa , Minamisatuma , Kagoshima, 31°26′00″N, 130°10′05″E, set net, 36 m, M. Itou, 20 December 2007 ; KAUM –I. 19722, 54.9 mm SL, east of Sakinoyama, Kataura, Kasasa , Minamisatsuma , Kagoshima, 31°25′44″N, 130°11′49″E, set net, 27 m, M. Itou, 13 May 2009 ; KAUM –I. 24808, 49.5 mm SL, 1 km southwest off Kawajiri Fishing Port, Kaimonkawajiri, Ibusuki , Kagoshima, 31°10′N, 130°32′E, set net, 40 m, G. Ogihara & T. Yoshida, 22 April 2009 ; KAUM–I. 26606, 51.5 mm SL, KAUM–I. 26607, 46.6 mm SL, KAUM–I. 26608, 53.1 mm SL, KAUM–I. 26609, 50.3 mm SL, KAUM–I. 26610, 48.9 mm SL, KAUM –I. 26617, 48.7 mm SL, 1 km southwest off Kawajiri Fishing Port, Kaimonkawajiri, Ibusuki , Kagoshima, 31°10′N, 130°32′E, set net, 40 m, G. Ogihara et al., 24 February 2010 ; KAUM–I. 27536, 53.2 mm SL, KAUM–I. 27537, 49.9 mm SL, KAUM–I. 27539, 49.6 mm SL, KAUM–I. 27541, 50.0 mm SL, KAUM–I. 27542, 51.1 mm SL, KAUM –I. 27544, 46.4 mm SL, 1 km southwest off Kawajiri Fishing Port, Kaimonkawajiri, Ibusuki , Kagoshima, 31°10′N, 130°32′E, set net, 40 m, G. Ogihara & T. Yoshida, 10 March 2010 ; KAUM–I. 29641, 54.2 mm SL, KAUM –I. 29642, 55.6 mm SL, off south coast of Ombosaki, Take-shima island, Mishima , Kagoshima, 30°48′32″N, 130°24′33″E, hand net, 5–40 m , KAUM fish team, 27 May 2010; KAUM–I. 29756, 55.1 mm SL, KAUM –I. 29757, 52.5 mm SL, off south coast of Ombosaki, Take-shima island, Mishima , Kagoshima, 30°48′32″N, 130°24′33″E, hand net, 5–20 m , KAUM fish team, 27 May 2010.

Diagnosis A species of Rhabdamia with the following combination of characters: dorsal-fin rays VI-I, 9; analfin rays II, 12; pectoral-fin rays 12–14 (modally 13); developed gill rakers 22–27 (modally 24); gill rakers including rudiments 23–27 (modally 24–25); snout and tip of lower jaw with black pigmentation; blackish blotches absent from opercle and anterior of body; black pigmentation scattered over entire caudal fin.

Description. Meristics and morphometrics of the type and non-type specimens are shown in Table 1. Data for the lectotype is presented first, followed by paralectotypes and non-type data (if different) in parentheses.

Body oblong, moderately deep and compressed; deepest at first dorsal-fin origin. Dorsal and ventral profiles of head and body convex. Caudal peduncle moderately deep. Head large, compressed. Eye large, rounded, orbit diameter 3.4 (2.8–4.2) in HL. Mouth moderate in size, oblique, forming angle of ca. 40 degrees to horizontal axis of body. Posterior margin of maxilla extending beyond vertical through anterior margin of eye; posterior edge of maxilla slightly concave; supramaxilla absent. Upper-jaw length 2.7 (2.3–3.0) in HL. Lower jaw projecting, its tip thickened and fitting into median indentation in upper jaw. No enlarged caniniform teeth on jaws. Villiform teeth in 1–3 rows on both jaws; several tiny teeth on vomer; teeth absent on ectopterygoid. Scattered papillae on upper surface of tongue. Anterior nostril with short oval tube, uppermost margin of opening below level of dorsal margin of pupil. Posterior nostril oval, opening vertically, without rim, uppermost margin below level of dorsal margin of orbit. Gill rakers slender, moderately long. Gill filaments shorter than gill rakers. Single, flat, obtuse opercular spine. Preopercular and opercular margins smooth.

Body scales cycloid, thin and deciduous. Lateral line well developed, more or less parallel with dorsal contour of body, ending a little beyond caudal-fin base. No scales on dorsal and anal fins, but a low sheath along bases of second dorsal and anal fins; small scales basally on caudal fin; midventral scales on bases of pelvic fins, paired fins otherwise lacking scales.

Vertebrae 10 + 14. Formula for supraneural bones, anterior neural spines and anterior dorsal pterygiophores 0/ 0/1/1+1/1/1/1/. Caudal skelton ( Fig. 8 ): five hypurals (first to fourth hypurals firmly fused, fifth free), three epurals, one parhypural, uroneurals and autogenous haemal spines absent.

First dorsal-fin origin posterior to vertical through pectoral-fin base; second spine of first dorsal fin damaged (second spine longest, its length 2.7–3.9 in HL). Posterior end of first dorsal-fin base anterior to vertical through posterior tip of depressed pelvic fin; all dorsal-fin soft rays branched. Second dorsal-fin origin anterior to vertical through anal-fin origin; second dorsal fin with concave margin; first dorsal spine length of second dorsal fin 3.5 (2.7–4.6) in HL; second dorsal-fin rays damaged (first soft ray of second dorsal fin longest, its length 1.8–2.5 in HL); all second dorsal-fin rays branched. Posterior end of second dorsal-fin base posterior to vertical through base of ninth (or eighth) anal-fin soft ray. Anal-fin origin below base of first soft ray of second dorsal fin; first spine of anal fin short, its length 16.1 (8.5–23.0) in HL; second anal spine 4.2 (3.5–5.2) in HL; anal-fin rays damaged (first soft ray of anal fin longest, its length 2.1–3.3 in HL); all anal-fin rays branched. Pelvic-fin origin anterior to vertical through origin of first dorsal fin; pelvic-fin spine long, its length 3.4 (2.6–4.2) in HL; first pelvic-fin soft ray longest, its length 2.6 (1.9–2.9) in HL. Posterior tip of depressed pelvic fin reaching to vertical through sixth spine base of first dorsal fin. Pectoral fin damaged (its length 1.2–1.6 in HL); pectoral-fin base narrow, its width 7.5 (5.6– 9.6) in HL. Caudal fin damaged (caudal fin forked, its upper lobe length 1.3–1.8 in HL).

Color of fresh specimens —Body semi-translucent pinkish with silvery abdomen. Females of this species with one or two longitudinal reddish-brown to blackish stripes on lateral surface of body from above pectoral-fin base to below posterior end of second dorsal-fin base (sometimes to below posterior end of first dorsal-fin base). Snout and tip of lower jaw yellowish with black pigmentation. Posteroventral margin of orbit with diffuse black pigmentation (rarely absent). First and second dorsal, and pectoral fins translucent red. Anal fins translucent red (tip sometimes yellowish). Pelvic fin translucent. Caudal fin translucent red, with black pigmentation on tips of lobes.

Color of preserved specimens —Head and trunk pale yellow. Black stripe and blotches on head and body. Caudal fin blackish, other fins translucent.

Distribution. Currently known from the northern Indian Ocean ( Seychelles, Maldives and Andaman Sea) and western Pacific Ocean ( Japan, Indonesia, Malaysia, and Australia) ( Fig. 7 ). Collection data for the specimens examined indicated capture depths from 5 to 83 m.

Remarks. Rhabdamia gracilis was originally described by Bleeker (1856) based on 39 specimens collected from Indonesia, one having been apparently lost since (R. de Ruiter, pers. comm.). Of the remaining 38 syntypes, one specimen (38.1 mm SL) was identified as Verulux solmaculata Yoshida & Motomura 2016 (re-registered as RMNH.PISC 34136), the others being conspecific and recognized here as R. gracilis .

Bleeker’s (1876–1877) figure of R. gracilis (as Amia gracilis ) illustrates characters of both R. gracilis and V. solmaculata : i.e., VI-I, 9 dorsal-fin rays; II, 12 anal-fin rays; a black stripe from above the pectoral-fin base to the middle of the caudal peduncle; a black stripe from the posterior margin of the orbit to the end of the opercle; a black stripe from the snout to the anterior margin of the orbit; a black blotch at the caudal-fin base; and a black band along each caudal fin lobe. The first three characters are applicable to R. gracilis and the remainder to V. solmaculata (see Yoshida & Motomura 2016; this study). Clearly, Bleeker’s figure of R. gracilis was based on more than one specimen, thereby nullifying the ICZN recommendation ( ICZN 1999: article 74.7, recommendation 74B) that an illustrated specimen be designated as lectotype. Consequently, RMNH.PISC 5609 (30.7 mm SL, Fig. 5 ), which has been preserved in good condition, is herein designated as the lectotype of R. gracilis , the remaining syntypes becoming paralectotypes (re-registered as RMNH.PISC 34135).

Rhabdamia gracilis exhibits sexual dichromatism, females having one or two longitudinal reddish-brown to blackish stripes from above the pectoral-fin base to below the posterior end of the second dorsal-fin base (sometimes to below posterior end of first dorsal-fin base), such stripes being absent in males ( Mabuchi, 2001; Yoshida and Motomura, 2013; this study). Examination of 98 R. gracilis specimens in the present study found that only female specimens> 41.3 mm SL had black stripes on the lateral surface of the body, such being absent in males and smaller females. On the other hand, R. spilota is considered to lack sexual dichromatism.

The largest examined individual of R. gracilis was 59.3 mm SL (NSMT-P 100281) collected from Iburi, Tosashimizu, Kochi, Japan.

Figures

FIGURE 5. Lectotype of Rhabdamia gracilis (RMNH.PISC 5609, 30.7 mm SL, Ternate, Moluccas, Indonesia).

FIGURE6. Fresh specimens of Rhabdamia gracilis (A, KAUM–I. 29641, 54.2 mm SL, B, KAUM–I. 29642, 55.6 mm SL, off south coast of Ombosaki, Take-shima island, Mishima, Kagoshima Prefecture, Japan).

FIGURE 7. Distributional recordsof Rhabdamia gracilis (based on specimensexamined herein).

FIGURE 8. Left side of caudal-fin complex of Rhabdamia gracilis (KAUM–I. 24808, 49.5 mm SL, cleared and stained). Abbreviations as in Fig.4. Scale 1 mm.