Introduction

The Indo-Pacific triplefin genus Enneapterygius Rüppell 1835, revised by Fricke (1997), currently includes 62 species regarded as valid and 47 species recorded from the Pacific Ocean (Fricke 1997; Holleman 2005; Motomura et al. 2005, 2015; Chiang and Chen 2008; Holleman and Bogorodsky 2012; Fricke and Erdmann 2017). The genus has been diagnosed by a discontinuous lateral line with an anterior series of 6–22 pored scales and posterior series of 13–27 notched scales, first dorsal fin with three spines, anal fin with one spine, pelvic fin with one spine and two soft rays, and head, opercle, pectoral-fin base and abdomen naked (abdomen with covered cycloid scales in some species) (Fricke 1997; Holleman 2005; Chiang and Chen 2008). However, synapomorphies for the genus have not been defined, and further investigation at the generic level is therefore necessary (Motomura et al. 2005, 2015).

Enneapterygius fuscoventer Fricke 1997 and Enneapterygius howensis Fricke 1997 are similar to each other, sharing some morphological features and similar male coloration. During a revisionary study of the genus, numerous additional specimens of the above two species were found in museum collections, as well as being newly collected from the western Pacific Ocean, including southern Japan and eastern Australia, respectively. Color recognition previously having been based only on preserved males (Fricke 1997), color descriptions are herein provided for both sexes, based on photographs of newly collected (fresh) specimens. In addition, revised diagnoses of E. fuscoventer and E. howensis are provided, following examination of type and non-type material, as well as distributional range extensions for both species.

Materials and methods

Counts and measurements followed Fricke (1997) and Holleman and Bogorodsky (2012), with the mandibular-pore formula following Hansen (1986). The pectoral-fin ray formula, which starts with the dorsalmost ray, represents unbranched + branched + unbranched rays = total pectoral-fin rays. Measurements were made to the nearest 0.1 mm with needlepoint calipers under a dissecting microscope. Standard length is abbreviated as SL. Curatorial procedures for newly collected specimens followed Motomura and Ishikawa (2013). Institutional abbreviations are as follows: Australian Museum, Sydney (AMS); Hiwa Museum of Natural History (HMNH); Kagoshima University Museum, Kagoshima (KAUM); Osaka Museum of Natural History, Osaka (OMNH); Queensland Museum, Brisbane (QM); Staatliches Museum für Naturkunde, Stuttgart (SMNS); Churashima Research Center, Okinawa Churashima Foundation, Motobu (URM); and Museum Support Center, National Museum of Natural History, Smithsonian Institution, Suitland (USNM).

Enneapterygius fuscoventer Fricke 1997

(English name: Blackbelly Triplefin; new Japanese name: Mitsudare-hebigimpo) (Figs. 1–6; Tables 1, 2)

Fig. 1
figure 1

Color photographs of fresh (a, c, e) and preserved (b, d, f) specimens of Enneapterygius fuscoventer in Japan. a, b KAUM–I. 63407, male, 18.7 mm SL, Nakano Island; c, d KAUM–I. 62812, male, 19.4 mm SL, Minamidaito Island; e, f KAUM–I. 63407, female, 24.5 mm SL, Okinawa Island

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Table 1 Counts and measurements, expressed as percentages of standard length, of Enneapterygius fuscoventer and E. howensis
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Table 2 Frequency distribution of selected fin ray and scale counts of Enneapterygius fuscoventer and E. howensis
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Enneapterygius fuscoventer Fricke 1997: 210, fig. 38 (type locality: Putic Island, Palawan Province, Philippines; paratype localities: Taiwan; Torobiriand Islands, Papua New Guinea; Rotuma Island, Fiji; Tutuila Island, American Samoa; Moorea and Tahiti islands, French Polynesia); Allen and Erdmann 2012: 766, unnumbered fig. (based on Fricke 1997).

Enneapterygius sp. 3: Yoshigou et al. 2005: 31 (Minamidaito Island, Daito Islands, Japan); Meguro 2014: 458, unnumbered fig. (Yoron Island, Ryukyu Islands, Japan).

Enneapterygius sp. 4: Kato 2014: 280, unnumbered fig. (Okinawa Island, Ryukyu Islands, Japan).

Holotype. USNM 259131, male, 22.8 mm SL, Putic Island, Palawan Province, Philippines, 10°91′81″N, 127°03′4″E, 0–4.6 m, V. Springer et al., 22 May 1978.

Paratype. USNM 293711, male, 19.9 mm SL, Songsong Bay, Batan Island, Batanes Province, Philippines, 2–3 m, G. Johnson et al., 2 May 1987.

Non-type material examined. 49 specimens, 13.9–26.0 mm SL. JAPAN: KUCHIERABU ISLAND: KAUM–I. 90903, female, 18.6 mm SL, Urasoko, Kuchierabujima, 30°29′16″N, 130°09′09″E, 8 m, K. Koeda, 19 Aug. 2016. NAKANO ISLAND: KAUM–I. 63407, male, 18.7 mm SL, KAUM–I. 63408, male, 19.0 mm SL, west side of Nakano-shima Port, 29°50′29″N, 129°50′39″E, 0.5–2 m depth, S. Tashiro, 1 Sept. 2014. YORON ISLAND: KAUM–I. 47825, female, 14.5 mm SL, off Maehama Beach, 27°01′13″N, 128°26′26″E, 2–8 m, KAUM Fish Team, 13 Aug. 2012. OKINAWA ISLAND: KAUM–I. 28634, female, 24.5 mm SL, Yonesu, Itoman, 36°05′16″N, 127°41′15″E, 0.5–2.0 m, KAUM Fish Team, 15 Apr. 2005; URM-P 7031, male, 25.4 mm SL, tidepool at Yonesu, Itoman, 14 May 1979; URM-P 7042, 7 males, 18.0–22.2 mm SL, tidepool at Yonesu, Itoman, 19 Aug. 1982; URM-P 7035, male, 21.0 mm SL, tidepool at Rukan-sho Reef, southwest of Itoman, 23 Apr. 1982; URM-P 17307, 2 males, 25.5–25.7 mm SL, Maeda Point, Onna, 25 Apr. 1986. ISHIGAKI ISLAND: KAUM–I. 62822, male, 20.8 mm SL, KAUM–I. 62823, male, 20.0 mm SL, Ugan-zaki Point, Sakieda, 24°27′N, 124°04′E, 1 m, T. Yoshida and S. Tashiro, 13 July 2014. IRIOMOTE ISLAND: OMNH-P 20903, male, 16.9 mm SL, Unari-zaki point, Uehara, T. Suzuki and M. Hosokawa, 8 Aug. 2005; OMNH-P 33498, female, 14.6 mm SL, OMNH-P 33510, female, 14.6 mm SL, Unari-zaki Point, Uehara, T. Suzuki and M. Hosokawa, 14 Aug. 2007; OMNH-P 33979, male, 20.5 mm SL, Unari-zaki Point, Uehara, T. Suzuki and M. Hosokawa, 10 Mar. 2008; URM-P 18891, 19. 3 mm SL, Unari-zaki Point, Uehara, T. Yoshino et al., 10 July 1987. MINAMIDAITO ISLAND: HMNH-P 6504, male, 25.4 mm SL, HMNH-P 6505, female, 22.7 mm SL, Kaigunbo, Kyuto, H. Yoshigou, 29 Sep. 2004; HMNH-P 6628, 3 males, 23.2–24.7 mm SL, HMNH-P 6629, female, 23.9 mm SL, Kaigunbo, H. Yoshigou, 1 May 2003; KAUM–I. 62730, female, 20.8 mm SL, KAUM–I. 62731, male, 21.3 mm SL, KAUM–I. 62732, male, 16.4 mm SL, Kaigunbo, Kyuto, 25°49′59″N, 131°16′021″E, 0.1–0.5 m, K. Kuriiwa, 2 July 2014; KAUM–I. 49907, male, 26.0 mm SL, KAUM–I. 49908, female, 18.3 mm SL, KAUM–I. 49920, male, 19.5 mm SL, KAUM–I. 49921, female, 18.5 mm SL, KAUM–I. 49924, male, 30.0 mm SL, KAUM–I. 49925, male, 30.0 mm SL, KAUM–I. 49926, female, 17.9 mm SL, KAUM–I. 49947, male, 19.3 mm SL, KAUM–I. 49931, male, 17.2 mm SL, KAUM–I. 52160, male, 20.8 mm SL, KAUM–I. 52161, male, 20.5 mm SL, KAUM–I. 52162, male, 20.9 mm SL, KAUM–I. 52163, male, 20.0 mm SL, Honba coast, 25°52′19″N, 131°14′59″E, 0.4–0.7 m, K. Kuriiwa, 25 June 2012; KAUM–I. 62812, male, 19.4 mm SL, Honba coast, 25°52′19″N, 131°14′59″E, 0.1–0.5 m, S. Chiba et al, 10 July 2014. TAIWAN: USNM 345517, male, 23.1 mm SL, southwest Taiwan, 0.8 m, V. Springer et al., 26 Apr. 1968. PHILIPPINES: USNM 325710, male, 19.1 mm SL, female, 15.6 mm SL, Balugan Bay, Batan Islands, Batanes Province, 6 m, A. Ross, 29 May 1985.

Diagnosis. A species of Enneapterygius with the following combination of characters: 11–13 (usually 12) second dorsal-fin spines; 16–18 (17) anal-fin soft rays; 18 (17–20) pored lateral-line scales; 34–36 (35) scale rows in longitudinal series; 3–5 + 1 + 3–5 (4 + 1 + 4) mandibular pores; no scale rows between posterior and anterior portions of pored and notched lateral-line scale rows, respectively; body yellowish with four reddish to brown bands, anterior three bands forked below lateral line, last band on caudal peduncle not H-shaped in pale males and females when fresh (Fig. 1e); lower two-thirds of head blackish, remaining part reddish, in nuptial males (Figs. 1a, c, 2, 3); body entirely blackish in nuptial males when fresh (Fig. 1a, c); dorsal-fin membrane translucent in both sexes (Figs. 1, 2); anal fin blackish in nuptial males (Figs. 1a–d, 2, 3); caudal fin blackish, with transparent margin in nuptial males (Figs. 1a–d, 2, 3); three oblique blackish bands on lateral surface of trunk, three blackish blotches on ventro-lateral surface of trunk in preserved males (Figs. 1b, d, 3); dorsal margin of body between blackish bands and caudal peduncle without blotches in preserved males (Figs. 1b, d, 2, 3).

Fig. 2
figure 2

Holotype of Enneapterygius fuscoventer (USNM 259131, male, 22.8 mm SL, Putic Island, Palawan Province, Philippines)

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Fig. 3
figure 3

Schematic depiction of preserved nuptial male coloration of Enneapterygius fuscoventer, based on 35 specimens from Japan. Dotted areas indicate melanistic areas. Closed and open arrows indicate bands and blotches, respectively (see text)

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Description. Counts and measurements given in Tables 1, 2; cephalic sensory pore system illustrated in Fig. 4.

Fig. 4
figure 4

Cephalic sensory pore system of Enneapterygius fuscoventer. Dorsal (a), lateral (b), and ventral (c) views of head (KAUM–I. 62730, female, 24.6 mm SL, Minamidaito Island, Japan). Scale bar 2 mm

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Dorsal fin III, XII, 9 (III, XI–XIII, 9–11); anal fin I, 17 (16–18); 16 (15–16) pectoral-fin rays; 35 (34–36) scale rows in longitudinal series; 18 (17–20) pored lateral-line scales; 17 (16–18) notched lateral-line scales; 12 circumpeduncular scales; 4 + 1 + 4 (3–5 + 1 + 3–5) mandibular pores.

Body moderately elongate, slightly compressed anteriorly, progressively more compressed posteriorly; dorsal profile of snout steep. Mouth slightly oblique; posterior margin of maxilla almost reaching level with or extending slightly beyond anterior margin of pupil. Anterior nostril, a membranous tube with thin, unbranched, distally broad tentacle; anterior nostril located at level of middle of eye, slightly closer to eye than to upper lip; posterior nostril opening elliptical. Eye oriented dorsolaterally, with a small, simple, distally narrow tentacle on posterodorsal margin, its length two-thirds that of nostril tentacle. Interorbital space narrow, its width slightly narrower than pupil diameter. Opercular margin reaching to below second spine base of first dorsal fin.

Lateral line discontinuous, with anterior series of pored scales and posterior series of notched scales; pored scale series ending below membrane between last spine of second dorsal fin and body; notched scale series beginning one scale below last pored scale (or below second scale from last pored scale), ending at caudal-fin base; anterior and posterior lateral line series adjacent, scale row absent between posteriormost pored scale and anteriormost notched scale; no scales on head (including maxilla, interorbital space and preopercle), opercle, pectoral-fin base, pre- and inter-pelvic-fin region, and pre-dorsal-fin region; no scales on fin membranes, except basally on caudal fin.

First dorsal-fin origin above opercular margin, 1st spine longest, 3rd spine shortest. Second dorsal-fin origin above 4–5th pored lateral-line scale, 2nd or 3rd spine longest. Third dorsal-fin origin above 20th to 21st longitudinal scale, 1st or 2nd fin ray longest. Pelvic-fin origin anterior to vertical through base of 1st spine of first dorsal fin; pelvic-fin rays relatively short, broad; posterior tips of 2nd pelvic-fin ray just reaching to anterior margin of anus. Base of uppermost pectoral-fin ray below 2nd pored lateral-line scale. Pectoral fin pointed posteriorly, 7th ray longest with posterior tip reaching to almost below or slightly beyond base of last spine of 2nd dorsal fin. Origin of anal fin below 6th or 7th spine base of 2nd dorsal fin.

Fresh color of nuptial males (Fig. 1a, c). Upper one-third of head from posterior part of interorbital to below 1st or 2nd spine of first dorsal fin red, gradually becoming blackish posteriorly; narrow region from posterodorsal margin of opercle to above uppermost ray of pectoral fin pale reddish; lower two-thirds of head (including snout) and body dense black; cheek behind upper jaw with bright blue blotch. First dorsal fin translucent with scattered brown, reddish and white spots between 1st and 2nd spines; spines reddish. Second and third dorsal fin translucent with white or blackish spots; spines reddish. Basal part of pectoral fin spotted with melanophores, dense basally; spines blackish basally, reddish distally. Pelvic-fin membrane translucent; rays blackish basally, reddish distally. Anal fin blackish. Caudal fin blackish, except for translucent distal margin.

Life color of nuptial males (Fig. 5a). Similar to fresh coloration, but with a bright white stripe extending from upper part of preopercle to upper part of pectoral-fin base. Pectoral fin with four white vertical bands, anteriormost continuous with bright stripe on upper part of fin base. Eye mottled with bright yellow to green blotches.

Fig. 5
figure 5

Underwater photographs of nuptial (a) and pale (b) males (different individuals) of Enneapterygius fuscoventer. Sakimotobu, Motobu, Okinawa Island, Japan, 3–5 m depth, 7 April 2014. Photo by T. Katano

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Color in preservative (nuptial males) (Figs. 1b, d, 2, 3). Upper one-third of head yellowish- white, remainder dense black; narrow region from posterodorsal margin of opercle to above uppermost ray of pectoral fin white. Body with three blackish vertical bands; first band basally from 4–7th spine of second dorsal fin to anterior part of anal-fin base; second band basally between posterior of second dorsal-fin and third dorsal-fin origin to base of 8–11th anal-fin ray; posteriormost band between 8th and last spine of third dorsal-fin base to posterior part of anal-fin base. Three blackish blotches below level of lateral line to ventral margin of body; first blotch on 6–8th pored lateral-line scales to abdomen; second blotch below 14–16th pored lateral-line scales to base of 4–6th anal-fin rays; posteriormost blotch below 7–8th notched lateral-line scales to base of 12–14th anal-fin rays. Remainder of body irregularly yellowish-white with scattered melanophores. Dorsal fin translucent. Pectoral fin translucent with scattered (basally dense) melanophores. Pelvic fin blackish, pale distally. Anal fin blackish. Caudal fin blackish, margin translucent.

Fresh color of pale males and females (Fig. 1e). Upper one-third of head and opercle yellowish; remainder of head white, mottled reddish or brown, with additional white blotches, spots and lines; two narrow stripes on snout and cheek, first extending from anterior tip of upper lip to anteroventral margin of pupil, second extending from ventral surface of head, posteriorly through jaw and posteroventrally through orbit to upper part of preopercle, interrupted on midpoint of cheek. Body yellowish, with scattered indistinct white blotches; four oblique, reddish or brown bands with scattered melanophores; first to third bands forked below lateral line; first band between posterior region of head and 4th dorsal-fin spine base to abdomen; second band basally between 6th and last spines of second dorsal fin to bases of 2nd or 3rd and 5th or 6th anal-fin rays; third band from third dorsal-fin base to bases of 10th or 11th and 14th or 15th anal-fin rays; second and third bands extending onto anal fin; posteriormost band on caudal peduncle. Ventral surface of body from posterior of head to pre-anal fin region white. First dorsal fin translucent with scattered yellowish, reddish and white spots between 1st and 2nd spines; spines reddish. Second and third dorsal fins translucent, spines reddish. Pectoral-fin base with two short, oblique, reddish stripes and scattered bright whitish spots; fin membrane translucent; rays reddish-brown with three bright whitish bands. Pelvic fin white. Anal fin translucent with four reddish bands continuous with lower forks of second and third body bands. Caudal fin translucent with broad reddish-brown bands medially.

Life color of pale males (Fig. 5b). Similar to fresh coloration of pale male, but eye mottled with bright yellow to green blotches, and head and body with scattered bright white blotches.

Color in preservative (pale males and females) (Fig. 1f). Head and body yellow or white. Four formerly reddish or brown bands pale or faded.

Distribution. Currently known from the western Pacific Ocean as follows: Ryukyu and Daito Islands, southern Japan; Taiwan; Batan and Putic islands, Philippines; Trobriand Islands, Papua New Guinea; Rotuma Island, Fiji; Tutuila Island, American Samoa; Moorea and Tahiti islands, French Polynesia (Fricke 1997; this study: Fig. 6). In Japanese waters, E. fuscoventer was collected from Kuchierabu Island (Osumi Islands), Nakano Island (Tokara Islands), Yoron Island (Amami Islands), Okinawa Island (Okinawa Islands), Ishigaki and Iriomote islands (Yaeyama Islands), and Minamidaito Island (Daito Islands) (this study). The species inhabits rocky shores in depths less than 5 m, where surge zones are constantly exposed to wave swells.

Fig. 6
figure 6

Distributional records of Enneapterygius fuscoventer (circles) and E. howensis (triangles). Closed and open symbols indicate localities of specimens examined in this study and examined by Fricke (1997), respectively

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Remarks. Characteristics of the Japanese specimens were consistent with those of the holotype (Fig. 2) and paratype of E. fuscoventer, and the original description given by Fricke (1997) in having the following features: XI–XIII (mode XII), 9–11 (9 or 10, rarely 11) second dorsal-fin rays; 16–18 (usually 17) anal-fin rays; 17–20 (usually 18) pored lateral-line scales; 15–19 (usually 17, rarely 15) notched lateral-line scales; 12 circumpeduncular scales; 3–5 + 1 + 3–5 (usually 4 + 1 + 4) mandibular pores; lower two-thirds of head blackish; body blackish with four pale vertical bands, first to third bands forked below lateral line; dorsal fin translucent; and anal and caudal fins blackish, except for translucent caudal fin margin (all color features applicable only to preserved males).

Some meristic and morphometric data for E. fuscoventer examined here differed from those given by Fricke (1997). The snout length [5.3–6.0% of SL in Fricke (1997)] was 6.9–10.3% in all specimens measured, including the holotype and paratype, indicating Fricke’s values to be inaccurate, or to exclude the upper-lip width. Furthermore, Japanese specimens differed from the western Pacific specimens examined by Fricke (1997) and in this study in having 15 or 16 pectoral-fin rays (vs. 16 or 17 in the latter) and 17–20 pored lateral-line scales (vs. 15–19), apparently representing intraspecific variations.

In the Northern Hemisphere, E. fuscoventer has previously been recorded only from Taiwan and the Philippines. The present specimens from the Ryukyu and Daito Islands represent the first records of E. fuscoventer from Japan, and those from Kuchierabu Island (Osumi Islands) being the northernmost records for the species (Fig. 6).

Enneapterygius howensis Fricke 1997

(English name: Lord Howe Island Triplefin) (Figs. 6–10; Tables 1, 2)

Enneapterygius howensis Fricke 1997: 224, fig. 42 (type locality: Lord Howe Island, New South Wales, Australia); Fricke 2002: 185 (Grande Terre, New Caledonia: listed as SMNS 19791 and 21940).

Holotype. AMS I. 17368-036, male, 30.0 mm SL, Lord Howe Island, New South Wales, Australia, 31°32′S, 159°04′E, AMS party, Feb. 1973.

Paratypes. AMS I. 17368-053, 8 males, 10.9–28.5 mm SL, 2 females, 24.6–32.5 mm SL, collected with holotype.

Non-type materials examined. 38 specimens, 11.4–32.2 mm SL, all from eastern Australia. AMS I. 17424-010, 29 males, 11.4–27. 2 mm SL, 7 females, 12.5–22.9 mm SL, Lord Howe Island, New South Wales, 31°53′S, 159°07′E, D. Hoese, 26 Feb.1973; QM I. 38311, male, 32.2 mm SL, female, 31.6 mm SL, northwest side of Flinders Reef, Queensland, 26°58′36″S, 153°29′06″E, 3–6 m, J. Johnson, 20 Aug. 2008.

Diagnosis. A species of Enneapterygius with the following combination of characters; 12–14 (mode 13) second dorsal-fin spines; 17–18 (18) anal-fin soft rays; 18–20 (19) pored lateral-line scales; 35–37 (36) scale rows in longitudinal series; 3–5 + 1 + 3–5 (4 + 1 + 4) mandibular pores; no scale rows between posterior and anterior portions of pored and notched lateral-line scale rows, respectively; body white to yellow with four oblique reddish bands, two anteriormost forked below lateral line, third and fourth forming H-shape in pale males and females when fresh (Fig. 7c); lower two-thirds of head blackish, remainder yellowish-white, in nuptial males (Figs. 7a, b, 8a–c, 9a, b); dorsal-fin membrane translucent in both sexes (Figs. 7, 8); anal fin blackish in nuptial males (Figs. 7a, b, 8a–c, 9); caudal fin blackish, margin transparent in nuptial males (Figs. 7a, b, 8a–c); three oblique blackish bands across lateral surface of trunk, two or three blackish blotches on ventro-lateral surface of trunk in preserved males (Figs. 7b, 8a–c, 9); dorsal margin of body between second and third blackish bands usually with a single blackish blotch in preserved males [Fig. 9a (sometimes absent; Fig. 9b)]; narrow vertical bar between second and third bands, extending from base of fourth or fifth soft rays of third dorsal fin to base of 13–15th rays of anal fin, gradually becoming wider ventrally [Fig. 9a (sometimes interrupted at lateral line; Fig. 9b)]; caudal peduncle with small paired blotches on dorsal and ventral margins, respectively, in preserved males (Figs. 7b, 8a–c, 9).

Fig. 7
figure 7

Color photographs of fresh (a, c) and preserved (b, d) specimens of Enneapterygius howensis from Flinders Reef, Australia. a, b QM I. 38311, male, 32.2 mm SL; c, d female, 31.6–mm SL. Photos of fresh specimens by J. Johnson

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Fig. 8
figure 8

Color photographs of preserved specimens of Enneapterygius howensis from Lord Howe Island, Australia. a AMS I. 17368-036, holotype, male, 30.0 mm SL; b AMS I. 17424-010, male, 25.2 mm SL; c AMS I. 17424-010, male, 24.0 mm SL; d AMS I. 17368-053, paratype, female, 24.6 mm SL

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Fig. 9
figure 9

Schematic depiction of preserved nuptial male coloration of Enneapterygius howensis, based on 38 specimens from Australia. Dotted areas indicate melanistic areas. Closed and open arrows indicate small blotches and bar, respectively (see text)

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Description. Counts and measurements given in Tables 1, 2; cephalic sensory pore systems illustrated in Fig. 10.

Fig. 10
figure 10

Cephalic sensory pore system of Enneapterygius howensis. Dorsal (a), lateral (b), and ventral (c) views of head (AMS I. 17424-010, male, 24.0 mm S, Lord Howe Island, Australia). Scale bar 2 mm

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Dorsal fin III, XIII (XII–XIV), 10 (9–11); anal fin I, 18 (16–19); 16 (15–16) pectoral-fin rays; 36 (35–37) scale rows in longitudinal series; 18 (17–20) pored lateral-line scales; 19 (16–19) notched lateral-line scales; 12 circumpeduncular scales; 4 + 1 + 4 (3–5 + 1 + 3–5) mandibular pores.

Body moderately elongate, slightly compressed anteriorly, progressively more compressed posteriorly; dorsal profile of snout steep. Mouth slightly oblique; posterior margin of maxilla almost reaching level with or extending slightly beyond anterior margin of pupil. Anterior nostril a membranous tube with thin, unbranched, distally broad tentacle; anterior nostril level with of middle of eye, slightly closer to eye than upper lip; posterior nostril opening elliptical. Eye oriented dorsolaterally, with a small, simple, distally narrow tentacle on posterodorsal margin, its length two-thirds length of nostril tentacle. Interorbital space narrow, its width slightly narrower than pupil diameter. Opercular margin reaching to below 2nd spine base of first dorsal fin.

Lateral line discontinuous, with anterior series of pored scales and posterior series of notched scales; pored scale series ending below membrane between last spine of second dorsal fin and body; notched scale series beginning one scale below last pored scale (or below second scale from last pored scale) and ending at caudal-fin base; anterior and posterior lateral line series adjacent, scale row absent between posteriormost pored scale and anteriormost notched scale. Body scales ctenoid; no scales on head (including maxilla, interorbital space and preopercle), opercle, pectoral-fin base, pre- and inter-pelvic-fin region, and pre-dorsal-fin region; no scales on fin membranes, except for basal part of caudal fin.

First dorsal-fin origin above opercular margin, 1st spine longest, 3rd spine shortest. 2nd dorsal-fin origin above 4th or 5th pored lateral-line scale, 2nd or 3rd spine longest. Third dorsal-fin origin above 21st or 22nd longitudinal scale, 1st or 2nd fin ray longest. Pelvic-fin origin anterior to vertical through base of first dorsal-fin spine; pelvic-fin rays relatively short, broad; posterior tips of second pelvic-fin ray just or not reaching to anus. Uppermost pectoral-fin ray base below 2nd pored lateral-line scale. Pectoral fin pointed posteriorly, seventh ray longest with posterior tip reaching to almost below or slightly beyond base of last spine of second dorsal fin. Origin of anal fin below 6th or 7th spine base of second dorsal fin.

Fresh color of males (Fig. 7a). Lower two-thirds of head, including, snout, lips, cheek, and opercle, and pectoral-fin base greenish-white with scattered melanophores; cheek behind upper jaw with bright blue blotch. Remainder of head from posterior part of interorbital to below base of first dorsal fin red. Body greenish-white with tiny scattered melanophores; four oblique reddish-brown bands, with widely spaced melanophores; first band between posterior region of head and 4th dorsal-fin spine base to abdomen; second band forked below pored lateral-line scales, from basal part of 6–12th spines of second dorsal-fin to 3rd or 4th and 6–7th rays of anal fin; third and fourth bands indistinctly H-shaped; third band between posteriormost ray of second dorsal fin and third dorsal-fin base to posterior part of anal-fin base; posteriormost band on caudal peduncle. First dorsal fin translucent with scattered reddish-brown spots between 1st and 2nd spines; spines reddish. Second and third dorsal-fin membranes translucent; spines reddish. Pectoral-fin base with scattered melanophores, two short oblique reddish bands; fin membrane translucent; spines reddish. Pelvic fin white with spotted melanophores basally. Anal fin translucent with scattered melanophores. Caudal fin blackish, distal margin translucent.

Fresh color of females (Fig. 7c). Upper one-third of head and opercle yellowish, remainder white, mottled with reddish or brown blotches, spots and lines; two narrow stripes on snout and cheek, first extending from anterior tip of upper lip to anteroventral margin of pupil, second extending from ventral surface of head posteriorly through jaw and posteroventrally through orbit to upper part of preopercle, interrupted on middle of cheek. Body white to yellowish; four oblique, reddish-brown bands; second band forked below lateral line, extending basally between 6th and last spines of second dorsal-fin to 3rd and 4th, and 6th and 7th anal-fin ray bases; third band H-shaped, from third dorsal-fin base to 12–14th and posteriormost three anal-fin ray bases; posteriormost band on caudal peduncle, H-shaped. First dorsal fin translucent; membrane between 1st and 2nd spines pale yellow. Second and third dorsal-fin membranes translucent; spines reddish. Pectoral-fin base with two short oblique reddish stripes; fin membrane translucent; rays reddish with three whitish bands. Pelvic fin white. Anal fin translucent, with four reddish bands continuous, respectively, with lower forks of second and third body bands. Caudal fin translucent, with broad reddish-brown bands medially.

Color in preservative (males) (Figs. 7b, 8a–c, 9). Lower two-thirds of head, including snout, lips, cheek and opercle, and pectoral-fin base black; remainder of head white; narrow region from posterodorsal margin of opercle to above uppermost pectoral-fin ray white. Body with three oblique blackish bands; first band basally between 4–7th spines of second dorsal fin to anterior part of anal-fin base; second band between posterior part of second dorsal-fin base and third dorsal-fin origin to base of 8–11th anal-fin ray; posteriormost band between 8th and posteriormost rays of third dorsal-fin base to posterior part of anal-fin base. A single blackish blotch (sometimes absent) dorsally at midpoint between second and third bands. Three blackish blotches along body below level of lateral line to ventral margin of body; first blotch extending from 6–8th pored lateral-line scales to abdomen; second blotch between first and second vertical bands, extending below 15–16th pored lateral-line scales to base of 4–6th anal-fin rays; third blotch extending from 4th and 5th rays of third dorsal-fin base to base of 13–15th rays of anal fin, becoming gradually wider ventrally (sometimes interrupted at lateral line); midpoint of caudal peduncle with single dorsal and ventral blotches. Remainder of body yellowish-white with scattered melanophores. Dorsal fin translucent. Pectoral fin translucent with scattered melanophores basally. Pelvic-fin base translucent with melanophores scattered basally and in the mid fin region. Anal fin blackish. Caudal fin blackish with translucent margin.

Color in preservative (females) (Figs. 7d, 8d). Head and body yellowish-white with scattered melanophores dorsally to mid-laterally on body, forming three indistinct paired bands (melanophores sometimes absent). First dorsal fin translucent; membrane between 1st and 2nd spines with scattered melanophores. Caudal peduncle with scattered melanophores, formerly reddish or brown bands pale or faded. Caudal fin translucent with two indistinct grayish bands.

Distribution. Currently known only from New Caledonia (Fricke 2002), Lord Howe Island (New South Wales), Tasman Sea (Fricke 1997; this study); and Flinders Reef (Queensland), Coral Sea (this study) (Fig. 6).

Remarks. The original description of Enneapterygius howensis was based on 15 specimens (Fricke 1997), 11 of which were re-examined in this study. These specimens plus 38 new specimens indicated the number of second dorsal-fin spines for E. howensis to be 12–14 (mode 13), differing from that (11–14, mode 11) given by Fricke (1997). Fricke (1997: table 14) inaccurately stated that the number of second dorsal-fin spines was counted from 21 specimens, although he examined only 15 specimens of the species. Thus, Fricke’s count of the second dorsal-fin spines of E. howensis is likely to be incorrect, and specimens of other species were possibly included.

Enneapterygius howensis has previously been recorded only from Lord Howe Island and New Caledonia (Fricke 1997, 2002). The two specimens from Flinders Reef, Queensland examined in this study represent the first records of E. howensis from a coral reef off coastal Australia.

Comparisons. Enneapterygius fuscoventer is a member of the Enneapterygius pyramis group, characterized by the following characters: medium-sized body; moderately high first dorsal fin; relatively long anterior lateral-line series, with 13–22 pored lateral-line scales; posterior series of lateral line separated by 0 or 1 scale row between anterior and posterior portions of notched and pored lateral-line scale rows, respectively; cheek sometime stippled with dark spots; lower body with dark triangular blotches (Fricke 1997). The group includes six species (Fricke 1997): E. fuscoventer Fricke 1997; E. howensis Fricke 1997; Enneapterygius kermadecensis Fricke 1994; Enneapterygius ornatus Fricke 1997; E. pyramis Fricke 1994; and Enneapterygius randalli Fricke 1997.

Within the E. pyramis group, E. fuscoventer is most similar to E. howensis, sharing the following features: 15–19 (usually 17) notched lateral-line scales; 3–5 + 1 + 3–5 (usually 4 + 1 + 4) mandibular pore formula; body entirely blackish, except for four pale vertical bands, the first three double-forked ventrally; dorsal-fin membrane translucent; anal fin entirely blackish; caudal fin blackish, translucent distally (Fricke 1997; this study). However, E. fuscoventer can be distinguished from E. howensis by the following characters: 11–13 (usually 12) second dorsal-fin rays [12–14 (13) in E. howensis]; 16–18 (17) anal-fin rays [17–18 (18)]; 17–20 (18) pored lateral-line scales [18–20 (19)]; 34–36 (35) scale rows in longitudinal [35–37 (36)] (Tables 1, 2).

Fricke (1997) stated that E. fuscoventer has larger eyes (8.8–10.5% of SL) and shorter pre-anal-fin length (46.0–49.8%), compared with E. howensis (7.7–8.9% and 50.2–51.9%, respectively, in E. howensis). However, the present study showed broad overlaps in these morphometrics between the two species (Table 1).

Limited to preserved specimens only, Fricke (1997) stated that both Enneapterygius fuscoventer and E. howensis specimens had dark triangular blotches on the lower sides of the body. However, such blotches were not evident in specimens examined here. Pale male and female E. fuscoventer differed from those of E. howensis (fresh examples of both species) in having the third body band forked below the lateral line, forming a reversed U-shape (Fig. 1e vs. forked above and below the lateral line, forming an H-shape in E. howensis; Fig. 7c). The posteriormost band (on the caudal peduncle) was not forked in E. fuscoventer (Fig. 1e vs. H-shaped; Fig. 7c).

The patterns of blackish bands and blotches were different in preserved male E. fuscoventer and E. howensis. Although E. howensis usually had a single blackish blotch on the dorsal margin of the body between the first and second blackish bands (Fig. 9a), such a blotch was always absent in E. fuscoventer (Fig. 3). In addition, E. howensis had a narrow vertical bar between the second and third bands, extending from the base of the fourth or fifth soft rays of the third dorsal fin to the base of the 13–15th rays of the anal fin, the bar gradually becoming wider ventrally [Fig. 9a (sometimes interrupted at the lateral line; Fig. 9b)]. However, E. fuscoventer had only a blotch below the lateral line between the second and third bands, never extending above the lateral line (Fig. 3). Moreover, the caudal peduncle had single small blotches on the dorsal and ventral margins in E. howensis (Fig. 9), with such blotches being absent in E. fuscoventer (Fig. 3).