Monocentris chrysadamas, Su & Lin & Ho, 2022

Su, Yo, Lin, Hsiu-Chin & Ho, Hsuan-Ching, 2022, A new cryptic species of the pineapple fish genus Monocentris (Family Monocentridae) from the western Pacific Ocean, with redescription of M. japonica (Houttuyn, 1782), Zootaxa 5189 (1), pp. 180-203 : 190-196

Monocentris chrysadamas sp. nov.

urn:lsid:zoobank.org:act:8F8CEFC7-19C2-44BD-9019-5437BE7AF6F2

New English name: Golden-diamond pineapple fish

New Chinese name: ḔṖṘ梨⁂

Figs. 2 , 5B , 7–10 , 12B , 13–14 . Tables 2–4

Monocentris japonica (non Houttuyn): Fourmanoir 1981:91; Kweon in Kim & Nakaya 2013:68.

Monocentris japonicus (non Houttuyn): Shimizu in Masuda et al. 1984:109; Okamura & Amaoka 1997:158; Shao et al. 2013:41; Koeda in Koeda & Ho 2019:442

Holotype. NMMB-P36126 (115.5 mm SL), off Dong-gang (ca. 22°22'22"N, 120°27'34"E), Pingtung, southwestern Taiwan, northern South China Sea, 20 Oct. 2021, bottom trawl, collected by Y. Su and S.-C. Chung. COI: ON025560 .

Paratypes. Twenty-five specimens, 38.8–127.6 mm SL. Taiwan (18): AIM MA73643 (2 specimens, 90.5– 105.4) and FMNH 146587 (2, 89.2–111.8), out of NMMB-P22837 . DOS 08609 (1, 82.1), off Ke-Tzu-Liao, 25 Aug. 2021, bottom trawl, coll. Y. Su, N.-S. Leung, and S.-L. Ng, COI: ON025564 . KAUM –I.111010 (1, 115.9), off Donggang, 27 Nov. 2017, bottom trawl, coll. K. Koeda, S. Tashiro and S. Morishita, COI: ON025565 . NMMB-P20499 (1, 118.3), off Dong-gang fishing port, Pingtung, southwestern Taiwan, 21 Mar. 2013, bottom trawl, coll. H.-C. Ho. NMMB-P22837 (2, 87.6–87.9), off Ke-Tzu-Liao (ca. 22°42'53"N, 120°13'12"E), Kaohsiung, southwestern Taiwan, 11 Feb. 2015, bottom trawl, coll. H.-C. Ho. NMMB-P24006 (1, 38.8), off Ke-Tzu-Liao, Kaohsiung, southwestern Taiwan , 12 Mar. 2015, bottom trawl, coll. H.-C. Ho. NMMB-P27579 (1, 49.1), off Ke-Tzu-Liao, bottom trawl, 6Apr. 2017, coll. H.-C. Ho. NMMB-P 30666 (1, 114.0), off Dong-gang, 25 Oct. 2018, bottom trawl, coll. K. Koeda and M.-Y. Lee. NMMB-P31576 (1, 96.3), off Dong-gang, 21 Mar. 2018, bottom trawl, coll. H.-C. Ho. NMMB-P36127 (1, 110.7), off Dong-gang, 17 Sep. 2021, bottom trawl, coll. S.-L. Ng, COI: ON025561 . NMMB-P 36128 (1, 100.9), off Dong-gang, 29 Oct. 2021, bottom trawl, coll. S.-L. Ng. NMMB-P36129 (1, 43.5), off Ke-Tzu-Liao, 1 May 2021, bottom trawl, coll. Y. Su, COI: ON025562 . NMMB-P36131 (1, 86.0), off Ke-Tzu-Liao, 17 Feb. 2022, bottom trawl, coll. Y.-C. Chen. NMMB-P 36136 (1, 103.9), dried specimen, off Ke-Tzu-Liao, coll. H.-C. Ho. Vanuatu (4): MNHN 2010-0778 (1, 127.6), MNHN 2010-0779 (1, 120.9), MNHN 2010-0781 (1, 123.3), MNHN 2010-0782 (1, 116.9), 15°33'46.8"S, 167°18'54.0"E, Tutuba, 330–341 m, 30 Sep. 2006. Solomon Islands (1): MNHN 2014-0261 (1, 108.2), 10°25'60.0"S, 161°24'00.0"E, San Cristobal , 190–232 m, 23 Sep. 2007. Australia (2): AMS I.25805-009 (1, 116.7), R / V Soela , st. SO1/86/11, north of Townsville , Queensland, 18°00'00.0"S 147°04'00.0"E, 260–264 m, 10 Jan. 1986. CSIRO H 3642-14 (1, 107 mm SL), east of Rockingham Bay , Queensland, 18°03'24.0"S, 147°04'48.0"E, 30 Nov. 1993, coll, G. Yearsley .

Non-types. Eighty specimens, 37.1–123.3 mm SL. Taiwan (68): NMMB-P08072 (1, 50.7), off Dong-gang , Pingtung, southwestern Taiwan, 16 Jun. 2016 , bottom trawl, coll. Y.-M. Ju. NMMB-P08360 (1, 96.5), off Donggang , 16 Mar. 2005 , coll. Y.-M. Ju. NMMB-P11962 (1, 82.6), off Dong-gang , 26 Feb. 2011 , bottom trawl, coll. H.- C. Ho. NMMB-P15423 (1, 91.0), no other data . NMMB-P21017 (1, 103.8), off Dong-gang , 12 Mar. 2014 , bottom trawl, coll. H.-C. Ho. NMMB-P24444 (1, 81.5), off Ke-Tzu-Liao, Kaohsiung, southwestern Taiwan, 19 Mar. 2016 , bottom trawl, coll. H.-C. Ho. NMMB-P21995 (1, 63.3), off Dong-gang , 25 Sep. 2013 , bottom trawl, coll. H.-C. Ho. NMMB-P22427 (1, 103.2), off Dong-gang , 17 Feb. 2015 , bottom trawl, coll. H.-C. Ho. NMMB-P28218 (1, 102.6), off Dong-gang , 13 Oct. 2017 , bottom trawl, coll. H.-C. Ho. NMMB-P32733 (1, 110.5), off Dong-gang , 18Aug. 2010 , bottom trawl, coll. C.-W. Chang. NMMB-P33032 (9, 88.0‒114.0), off Dong-gang , 19 Jul. 2019 , bottom trawl, coll. H.-C. Ho. NMMB-P34253 (1, 55.9), off Dong-gang , 15 May 2020 , bottom trawl, coll. H.-C. Ho. NMMB-P36137 (1, 74.6), dried specimen, collected with NMMB-P36136 . NMMB-P36200 (30, 81.0‒108.3) , NMMB-P36201 (17, 79.0‒118.0), off Tainan, western Taiwan, 150‒ 200 m . Australia (12): AMS I.25805-009 (6, 97.2‒117.2), R / V Soela, st. SO1/86/04, north of Townsville , Queensland, 18°00'S, 147°02'E, 220 m, 9 Jan. 1986 . CSIRO H 592-16 (1, 109.6), FRV Soela, sta. SO06/84/43, south of Flinder’s Reefs. Queensland, 17°57'S, 146°58'E, 212 m, 29 Nov. 1985 . CSIRO CA 1415 (1, 122.2), FRV Soela, sta. SO04/80/59, south of Clarke Reef , Western Australia, 1 8 ° 0 7 ' S, 119°21'E~ 18°08'S, 119°22'E, 160‒175 m, 12 Jun 1980 . CSIRO H 3642-22 (1, 108.1) and CSIRO H 3643-24 (1, 114.8), FRV Southern Surveyor , sta. SS0793 / T1 , east of Rockingham Bay , Queensland, 18°03.4'S, 147°04.8'E ‒ 18°00.5'S, 147°00.9'E, 205‒214 m, demersal trawl, 30 Nov. 1993 . CSIRO H 5635-21 (1, 118.4) and CSIRO H 5635-22 (1, 121.0), east of Rockingham Bay , Queensland, 17°36'S, 146°48'E ‒18°08'S, 147°09'E, demersal trawl, 223‒248 m, 21 Aug 2000 .

Possible hybrid individuals. Six specimens, all collected around Taiwan. NMMB-P33032 , 1 of 10, off Donggang, 19 Jul. 2019, coll. H.-C. Ho. NMMB-P36138 (1, 65.9), collected with NMMB-P36136 . NMMB-P36130 (1, 80.7), collected with NMMB-P36037 , COI: ON025563 . NMMB-P36202 (3, 98.5‒124.7), ca. 23°00'56.4"N, 119°56'02.2"E, off Tainan, 150‒200 m, 2021.

Etymology. The specific name chrysadamas , treated as a noun in apposition, is a combination of Greek “chrys” and “adamas”, meaning “golden” and “diamond”, in reference to its yellowish body color when alive and diamondshaped body scales. Moreover, the meaning of these two words in Chinese also refers to a famous agricultural variety of pineapple in Taiwan, which this new pineapple fish resembles.

Diagnosis. A species of Monocentris differing from its congeners in having following combination of characters: LLS 12–15; LLB1 10–11, modally 10; LLB3 6–7; total gill rakers 16–20; scales between LLB4 and AS small, its posterior tip not reaching second postpelvic scute; vomer without teeth; and mouth large, reaching a vertical through posterior margin of eye.

Description. Meristic and morphometric values are provided in Tables 2 and 3 . Data below are for the holotype, followed by the range for selected paratypes and non-types in parentheses, except where indicated.

Dorsal-fin rays VI, i+9=10 (V–VII, i–ii+8–10=10–12); anal-fin rays i+9=10 (i+9–10=10–11); principal caudalfin rays 10+9=19 (9–10+9=18–19), uppermost and lowermost rays unbranched; procurrent caudal-fin rays 5 (4–5) dorsally and 4 ventrally; pectoral-fin rays ii+11+i=14 (ii+10–12+0–i=13–15); pelvic-fin rays I, 3; developed gill rakers 6+1+12=19 (5–7+1+10–12=16–20); LLA1 14/13 (12–15/12–15); LLA2 5/5 (2–7/2–6); LLS 14/13 (12– 15/12–15); LLB1 10/10 (9–12/9–11, mode 10/10); LLB2 7/7 (7–9/7–8); LLB3 7/6 (6–7/6–7); LLB4 3 (prepelvic)+4 (postpelvic)/3+4; scales surrounding dorsal-fin base 22 (18–21); scales surrounding anal-fin base 6 (6–8); medium predorsal scales 4 (1–4, mode 3); abdominal scutes 2 (rudimentary)+3 (prepelvic)+4 (postpelvic) (rarely 2+2+4); vertebrae 12+14=26; pyloric caeca 8 (7, n=2); pseudobranchial filaments 16 (14–21); branchiostegal rays 8.

Body oblong, longer than deep, depth at dorsal-fin origin 1.7 (1.4–1.7) in SL. Head large, its length 2.2 (2.0– 2.3) in SL, and subequal to its height, 1.0 (0.9–1.0) in HL; upper profile in front of dorsal fin slightly rounded, with forehead region gently concave; forehead narrow, its width 4.3 (3.6–4.6) in HL; eyes moderately small, 3.4 (2.8– 3.2) in HL; snout broadly rounded, extending clearly before maxilla, its length 3.4 (2.9–3.9) or 3.8 (3.3–4.1) in HL; space between eyes convex and broad, interorbital width 2.7 (2.4–2.8) in HL; crests on head bones well-developed, connected by thin membranes with numerous tiny pores.

Mouth large, posterior end of maxilla (lower corner) extending clearly beyond vertical through posterior margin of eye. Nostrils nearly connected but separated by narrow membranes, both immediately in front of anterior margin of eye and above horizontal thorugh center of eye; posterior nostril much larger than anterior one. Long groove extending from symphysis of premaxillae to tip of snout. Small blunt dentigerous knob at each side of symphysis of dentaries, with concavity right behind the knob where the light organ is housed. Supramaxilla elongate, rectangular posteriorly, covering most of posterior portion of maxilla with long needle-like process at anterodorsal corner; posteroventral corner of maxilla exposed.

Most of lateral and medial surfaces of premaxilla and covered with villiform teeth; anterior third and inner portion of posterior two-thirds of dentary covered with villiform teeth, a long fleshy patch of papillae on outer portion of dentary; symphyseal notch of premaxilla and knob at symphysis of dentaries naked. Palatine with narrow band of teeth; vomer toothless. Gill rakers rod-shaped, somewhat laterally compressed, with villiform teeth on their tips and inner surfaces; those in outer row of first arch longest; rakers on inner row of first arch and both inner and outer rows of second to third arches short; small tooth patches forming bumps, present on midline of all four outer arches. Villiform teeth present on fifth ceratobranchial. Small villiform tooth patch on second pharyngeal arch forming oval patch. Large teardrop-like tooth patch on third pharyngeal arch.

Body scales enlarged and firmly attached to each other and slightly overlapped; spines on anterior scales rudimentary, and eventually developed as central spine pointing backward on posterior portion; pectoral-fin base covered with 3 rows of small cycloid scales; caudal-fin base covered with several small scales, each with a central spine; abdominal margin covered with single row of serrated scutes, the last forming a strong posterior spine; 2 small scales present between LLB4 and AS, posterior tip of second scale not reaching second postpelvic scute ( Fig. 4B ); isthmus with 1 or 2 enlarged scales; gular region naked, without scales.

Dorsal-fin spines thickened, second spine longest, and subsequent spines progressively shorter; first four spines connected by membranes at base and alternating side to side; base of spinous dorsal fin concave, forming a groove to house the spines; outer margin of soft dorsal fin rounded. Pectoral fin short, 1.6 (1.3–1.7) in HL, its tip reaching lateral line, but not reaching vertical through anal-fin origin. Pelvic-fin spine enlarged, its length 1.4 (1.1–1.6) in HL; abdominal scutes and LLB4 forming a large groove to receive pelvic-fin spine. Caudal-fin margin slightly concave, its lobes rounded. Pyloric caeca pale, unbranched.

Size. Moderately small species. The largest specimen examined was 127.6 mm SL, a female with well-developed eggs, implying it is a moderately small species and smaller than M. japonica .

Coloration. When fresh ( Figs. 7A , 8 ), body slightly yellowish. Underwater photo in Okamura & Amaoka (1997) shows a more bright-yellow body color, implying it has a bright-yellowish color when alive. Scales with black margin. Oral cavity, including underside of the tongue, peritoneum, and stomach whitish. Vomer, palatine, outer margin of premaxilla, and dentary black. When preserved, coloration similar to fresh but paler in appearance.

Otolith morphology. Two sagittal otoliths were taken from NMMB-P36200 (105.0 mm SL), 9.9 and 10.0 mm in length ( Fig. 9 ). Otolith square to rhomboidal, 9.4–9.5 % SL, length/depth ratio 1.14–1.17. Dorsal margin irregular crenate, divided into indistinct lobes; ventral margin convex, nearly straight; posterior margin entire, slightly convex and wave-like with a small pseudo-excisura and a blunt pseudo-rostrum; distal surface slightly depressed dorsally with some shallow grooves associated with the lobes on dorsal margin and convex ventrally with rough surface; proximal surface slightly concave; sulcus groove deep and wide, heterosulcoid, ostium clearly larger and wider than cauda, ostium opens anteriorly to excisura; colliculum heteromorph; crista superior well-developed to ridge-like, crista inferior not developed; rostrum convex; antirostrum small, blunt; a clear notch on excisura; dorsal depression deep and broad, extending from antirostrum to nearly posterior end of cauda; ventral depression absent.

Distribution. Records from literature and this study suggest a wide distribution in the western Pacific, including Taiwan ( Shao et al. 2013; Koeda & Ho 2019; this study), Korea ( Kim & Nakaya 2013), Japan (Shimizu in Masuda et al. 1984; Okamura & Amaoka 1997), the Philippines ( Fourmanoir 1981), Vanuatu (this study), the Solomon Islands (this study), and Western Australia and Queensland, Australia (this study). Records from Vanuatu imply it may inhabit depths to 341 m, slightly deeper than that of M. japonica .

Genetic analysis. The maximum-likelihood tree strongly supports the monophyly of both M. chrysadamas sp. nov. and M. japonica at species-level distinction, with a 99% and 81% bootstrap value, respectively ( Fig. 10 ). Although M. chrysadamas possesses two sub-clades on the tree, the genetic distance calculated by K2P model shows only a 0.835% difference among these two sub-clades, which is much lower than expected species-level differences ( Table 4 ). Overall, M. chrysadamas has a genetic distance of 3.566% with M. japonica , with an intraspecific distance of 0.424%.

Figures

FIGURE 2. Variation in medium-predorsal scales of Monocentris chrysadamas sp. nov., outlined by red dots. A. NMMB- P36126, holotype, 115.5 mm SL. B. NMMB-P36127, paratype, 110.7 mm SL.

FIGURE 4. Monocentris japonica (Houttuyn, 1782). A. KAUM–I.149072, 16.4 mm SL, juvenile, fresh, photo by KAUM. B. NMMB-36197, 1 of 3, 96.5 mm SL, a black individual, previously frozen.

FIGURE 5. Ventral view of Monocentris species showing scales between AS and LLB4 (outlined by red dots). A. M. japonica, KAUM–I.71509, non-type, 99.8 mm SL, preserved. B. M. chrysadamas sp. nov., DOS 08609, paratype, 82.1 mm SL, preserved. Anterior to left.

FIGURE 7. Monocentris chrysadamas sp. nov. NMMB-P36126, holotype, 115.5 mm SL. A. Fresh. B. Preserved.

FIGURE 8. Monocentris chrysadamas sp. nov. A. NMMB-P36131, paratype, 86.0 mm SL. B. KAUM–I.111010, paratype, 115.9 mm SL, fresh, photo by KAUM.

FIGURE 9. Sagittal otoliths taken from Monocentris chrysadamas sp. nov., NMMB-P36200, 1 of 30, non-type, 105.0 mm SL. Showing outer (A, C) and inner face (B, D). A–B. right side, 10.0 mm otolith length. C–D. left side, 9.9 mm otolith length

FIGURE 10. Maximum-likelihood tree based on COI sequences of Monocentris spp. generated by Kimura-2-parameter model (Kimura, 1980) with 1000 bootstrap pseudoreplicates, with Cleidopus gloriamaris chosen as the outgroup. Numbers beside each node represent bootstrap values, with values <75% omitted. Scale bar on bottom-left corner denotes the number of substitutions per unit length on tree.

FIGURE 12. Lateral view of pectoral-fin region, showing (A) an extra scale (red arrow) below pectoral-fin base in neotype of M. japonica, and (B) absent in paratype, DOS 08609, 82.1 mm SL, of M. chrysadamas. Anterior to left.

FIGURE 13. Allometric growth in M. chrysadamas sp. nov. (red circle) and M. japonica (blue triangle). A. Head depth (% SL vs. SL). B. Body depth (% SL vs. SL). C. Postorbital length (% SL vs. SL). D. Dorsal-fin–pelvic-fin length (% SL vs. SL). E. Dorsal-fin–pectoral-fin length (% SL vs. SL).

FIGURE 14. Frequency of standard length in M.chrysadamas sp. nov. (n=71) and M. japonica (n=66). Color of bars correspond with species' colors in key.