Pristiapogon taeniopterus ( Bennett, 1836 )

Abe, Kimiya, Sasaki, Daichi, Maclaine, James & Kimura, Seishi, 2023, First Northwest Pacific Record of the Apogonid Fish, Pristiapogon taeniopterus (Actinopteri: Kurtiformes) from Minamidaito Island, Okinawa Prefecture, Japan, Species Diversity 28 (1), pp. 117-122 : 117-121

Pristiapogon taeniopterus ( Bennett, 1836)

[English name: Banded Cardinalfish; new standard Japanese name: Sumihiki-ishimochi] ( Fig. 1 ; Table 1)

Apogon taeniopterus Bennett, 1836: 206 (type locality: Mauritius); Fraser and Lachner 1985: 29 (southern Indian Ocean eastward to the Marquesas Islands); Randall 1998: 35 (Hawaiian Islands); Randall 1999: 14 ( Pitcairn Islands); Randall et al. 2004: 14 ( Tonga).

Pristiapogon taeniopterus: Randall 2005: 211 ( Mauritius, Cocos-Keeling Islands, Christmas Island, Micronesia, New Caledonia, French Polynesia, Pitcairn Islands, and Hawaiian Islands); Randall 2007: 216 ( Mauritius, Cocos-Keeling Islands, Christmas Island, St. Brandon’s Shoals, Pitcairn Islands, Marquesas Islands, Hawaiian Islands, Mariana Islands and New Caledonia); Fricke et al. 2009: 53 ( Réunion); Mabuchi et al. 2014: 201 (list only); Fricke et al. 2018: 173 ( Madagascar); Kuiter and Kozawa 2019: 134 ( Mauritius, Cocos-Keeling Islands, Indian Ocean from Christmas Island, Micronesia and Polynesia); Fraser et al. 2022: 205, pl. 65 [Mascarenes and St. Brandon Shoals; elsewhere to Cocos (Keeling) Islands, Christmas Island, Marianas Islands, New Caledonia, Pitcairn Islands, Line Islands and Hawaii].

Material examined. FRLM 61029 , 74.7 mm SL, Minamidaito Fishing Port , Minamidaito Island, Okinawa Prefecture, Japan, 25.8687°N, 131.2278°E, hook and line, 1 January 2022, collected by K . Abe and D . Sasaki.

Diagnosis. A species of Pristiapogon with the following combinations of characters: developed gill rakers 2–4 + 12–14 = 15–17 (gill rakers including rudiments 4–6 + 15–18 = 21–23); circumpeduncular scales 15–18; upper-jaw length 17.9–21.5% SL; distinct dark stripes on both dorsal, anal, and both lobes of caudal fin; dark vertical bar just posterior to the base of caudal fin incompletely developed or interrupted at the central portion of the fin; dark band or blotch on posterior part of caudal peduncle just anterior to caudal-fin base; pectoral-fin rays usually 13 ( Fraser and Lachner 1985; this study).

Description. Counts and measurements are shown in Table 1. Body oval, compressed; deepest at origin of first dorsal fin; dorsal profile of head and body from snout to above posterior nostril rising somewhat steeply, thereafter rising gently to first dorsal-fin origin, almost parallel to body axis between first and second dorsal fins, declining somewhat steeply along base of second dorsal fin, slightly declining at caudal peduncle; ventral profile of head and body descending from lower-jaw tip to pelvic-fin insertion, then swelling gently, and elevated roundly from anal-fin origin to caudal-fin origin. Mouth large, inclined obliquely upward; posterior tip of upper jaw reaching slightly posterior to vertical thorough center of eye; anterior nostril forming minute tube with short flap on posterior margin, situated slightly anterior to midpoint between snout tip and anterior margin of eye; posterior nostril oval, situated dorsoposterior to anterior nostril; conical teeth arranged in five to seven and three or four rows on upper and lower jaws, respectively; vomer with one or two rows of conical teeth, forming a chevron-shaped tooth patch; palatine edentate; upper edges of infraorbitals, preopercular ridge, and posterior and ventral margins of preopercle serrated; ctenoid scales with short spines covering most part of cheek, operculum and body; cycloid scales on bases of pectoral and pelvic fins, and just behind caudal-fin base. Origin of first dorsal fin just located on vertical through insertion of pelvic fin, or second lateral-line scale; origin of second dorsal fin situated slightly anterior to vertical through origin of anal fin, or just on vertical through tenth lateral-line scale; origin of anal fin on just vertical through eleventh lateral-line scale; insertion of pectoral fin slightly posterior to vertical through origin of first dorsal fin, or just on vertical through third lateral-line scale; posterior tip of pectoral fin exceeding posteriorly beyond vertical through origin of anal fin; appressed pelvic-fin tip not reaching origin of anal fin; caudal fin forked. Lateral line complete, arc-shaped from upper margin of operculum to center of caudal peduncle, thereafter running straight to base of caudal fin. First to fifth hypurals and parhypural independent; uroneurals absent; three epurals.

Color of fresh specimen. Base color of body light brown, posterior margin of dorsolateral scales and exposed part of ventrolateral scales yellowish brown; breast below pectoral fin base to belly pinkish silver; dark brown band from tip of snout to anterior margin of eye with narrow silver line just below it; the silver line crossing lower eye and extending to opercle; lower jaw light yellow; posterior head silver to brown behind eye to operculum; dark brown patch on lower part of opercle to subopercle; iris yellowish, pupil black; distinct black vertical patch on posterior part of caudal peduncle just anterior to caudal-fin base; membranes between first and second spines, upper two-thirds of second and third spines, upper half of third and fourth spines of first dorsal fin blackish, forming a diagonal band, narrow white band just after blackish diagonal band, membranes behind white band yellowish semitransparent; prominent longitudinal dark brown stripes proximally on second dorsal- and anal-fin membranes, slightly broader than one-half diameter of pupil; white stripes above and below dark stripes on second dorsal and anal fins, upper white stripe on second dorsal fin somewhat unclear; two outer developed rays of both caudal-fin robes whitish, distinct black bars below and above those white rays; pelvic-fin spine and first soft ray whitish; membranes in other parts of second dorsal, anal, caudal and pelvic fins light brownish semitransparent; outer margins of all fins blackish except for light pink pectoral fin.

Color of preserved specimen. Head mostly dusky light brown; an indistinct dark band from tip of snout to eye; body light brown dorsally, somewhat silvery to tan ventrally; dark patches or stripes on operculum, caudal peduncle and fins remaining; all fins light brown except for dark stripes and blackish outer margin of pelvic fin. Stomach blackish brown; pyloric caeca and intestine including rectum pale yellowish white.

Distribution. Madagascar, Réunion, Mauritius, St. Brandon’s Shoals, Cocos-Keeling Islands, Christmas Island, Mariana Islands, Caroline Islands, Micronesia, New Caledonia, Marshall Islands, Samoan Island, Phoenix Islands, Tonga, Cook Islands, Hawaiian Islands, Line Islands, Society Islands, Tuamotu Archipelago, Marquesas Islands, Pitcairn Islands, and Minamidaito Island, Okinawa Prefecture, Japan ( Fraser and Lachner 1985; Randall 1998, 1999, 2005, 2007; Randall et al. 2004; Fricke et al. 2009, 2018; this study).

Remarks. The present specimen belongs to Pristiapogon according to the following combination of characters: first dorsal fin with seven spines; upper edge of infraorbitals, preopercular ridge, and posterior and ventral margins of preopercle serrated; gill rakers including rudiments 22; and palatine edentate ( Fraser and Lachner 1985; Mabuchi et al. 2014). The present specimen shares the following characters with the holotype of Apogon taeniopterus (BMNH 1855.12.26.478; Fig. 1C ): distinct dark stripes proximally on both second dorsal and anal fins, running parallel to their bases; distinct dark stripes near margins of both lobes of caudal fin; dark vertical bar posterior to the base of caudal fin incompletely developed; and 13 pectoral-fin rays. Additionally, some characters such as 3 + 14 developed gill rakers and 15 circumpeduncular scales agree well with those of P. taeniopterus in Fraser and Lachner (1985).

Fraser and Lachner (1985) recorded a “pale stomach and intestine” in their “Diagnosis” of the subgenus Pristiapogon . However, the present specimen has a dark stomach and a pale intestine. Also, the present comparative specimens of P. exostigma , P. fraenatus and P. kallopterus have blackish brown stomachs. The pyloric caeca and intestines of P. exostigma and P. fraenatus are pale yellowish white but those of P. kallopterus are blackish brown except for a pale rectum.

Pristiapogon taeniopterus closely resembles P. menesemus in having 15–17 developed gill rakers, and distinct dark stripes on both dorsal, anal and both lobes of the caudal fin. Fraser and Lachner (1985) mentioned that the former has an incompletely developed or interrupted vertical dark bar on the caudal fin, just posterior to the base (vs. a complete dark bar in the latter), and usually 13 pectoral-fin rays (vs. 14). However, they also indicated that a few of their specimens of P. taeniopterus (3 of 43 specimens) had an almost complete vertical dark bar on the caudal fin and small specimens of those two nominal species showed much similarity in coloration. They suggested that both species are perhaps a single, wide-ranging species, and populations in the Indo-Pacific region ( P. taeniopterus ) and Hawaii to Johnston Island ( P. menesemus ) may be in a subspecific relationship. On the other hand, Randall (1998, 2007) treated P. menesemus as a junior synonym of P. taeniopterus because of an erroneous count of pectoral-fin rays in Fraser and Lachner (1985), both nominal species having usually 13 rays. Kuiter and Kozawa (2019) regarded both nominal species as valid because P. menesemus has more defined dark stripes on the fins than P. taeniopterus and the former also lacks a distinct dark band or blotch on the posterior part of the caudal peduncle. They inferred that the former may be endemic to the Hawaiian region. However, their P. menesemus photographed at night ( Kuiter and Kozawa 2019: 134, bottom left) shows a faintly dark posterior caudal peduncle and incomplete vertical black band just posterior to caudal-fin base. These characters are consistent with P. taeniopterus . From these facts, it is currently unclear whether those two nominal species are valid or conspecific. Mabuchi et al. (2014: 201) treated P. menesemus as “status uncertain”.

Pristiapogon taeniopterus is distinguished from the three congeners found in Japanese waters by the following characters: circumpeduncular scales 15–18 (vs. 12 in P. exostigma , 12–13 in P. fraenatus , and 12–14 in P. kallopterus ), developed gill rakers 15–17 (vs. 10–13 in P. exostigma , 9–13 in P. fraenatus , and 10–14 in P. kallopterus ), pectoral-fin rays usually 13 (vs. 14 in P. fraenatus ) and no distinct longitudinal stripe laterally on body (vs. a distinct longitudinal stripe from snout to caudal-fin base in P. exostigma and P. fraenatus ) ( Fraser and Lachner 1985; this study).

Because a Japanese name has not previously existed for P. taeniopterus , the new Japanese standard name “Sumihiki-ishimochi” is herein proposed for the species, based on FRLM 61029 ( Fig. 1A, B ), “Sumihiki” meaning “line drawn with India ink” in reference to the distinct dark stripes on both dorsal, anal and both lobes of the caudal fin, and “ishimochi” being the Japanese name for some species of apogonids, which nearly all have large otoliths. “Ishi” meaning “stone” and “mochi” “possessing or having”.

The present collection site, Minamidaito Island, is an oceanic island, formed by an uplift of an atoll, located ca. 350 km east of Okinawa Island, Japan. The present specimen of P. taeniopterus was caught near the bottom in front of the quay at night in Minamidaito Fishing Port. The bottom is hard, but the exact substratum is unknown. The port was man-made by excavating land near the coast and partially opened in November 2000. In the port, P. kallopterus is dominant among the family Apogonidae , and Cheilodipterus quinquelineatus Cuvier, 1828 , Ostorhinchus nigrofasciatus (Lachner, 1953) and P. exostigma were also caught sympatrically with P. taeniopterus .

Comparative materials. Pristiapogon taeniopterus: BMNH 1855.12. 26.478, holotype of Apogon taeniopterus , 138.4 mm SL, Mauritius . Pristiapogon exostigma , 6 specimens, 77.9–92.0mm SL: FRLM 42740 ; 88.8 mm SL, Yoron Island , Kagoshima Prefecture, Japan; FRLM 50709 , 51439 ; 86.9–92.0 mm SL, Yonaguni Island , Okinawa Prefecture, Japan; FRLM 53596 ; 82.1 mm SL, Ishigaki Island, Okinawa Prefecture, Japan; FRLM 56558 , 61040 ; 77.9–81.1 mm SL, Minamidaito Island, Okinawa Prefecture, Japan . Pristiapogon fraenatus , 7 specimens, 65.7–70.9 mm SL: FRLM 15477 , 17457 ; 67.6–70.9 mm SL, Ishigaki Island , Okinawa Prefecture, Japan; FRLM 21570 , 22044 , 22045 , 23762 ; 61.5– 69.7 mm SL, Kotania Bay , Seram, Indonesia; FRLM 28901 ; 76.4 mm SL, Iriomote Island, Okinawa Prefecture, Japan . Pristiapogon kallopterus , 10 specimens, 83.0– 114.8 mm SL: FRLM 42837 ; 85.7 mm SL, Yoron Island , Kagoshima Prefecture, Japan; FRLM 43540 ; 103.9 mm SL, Ginama, Okinawa Prefecture, Japan; FRLM 50708 ; 91.8 mm SL, Yonaguni Island, Okinawa Prefecture, Japan; FRLM 56523 , 57192 , 61020 , 61022 , 61024 , 61030 , 61060 ; 83.0– 114.8 mm SL, Minamidaito Island, Okinawa Prefecture, Japan .

Figures

Fig. 1. Japanese specimen (fresh condition; A, B) and holotype (C) of Pristiapogon taeniopterus. A, B, FRLM 61029, 74.7mm SL, Minamidaito Island, Okinawa Prefecture, Japan; C, BMNH 1855.12.26.478 (© The Trustees of The Natural History Museum, London), 138.4mm SL, Mauritius. Scale bars: 10mm.