Trachinotus, Lacepede, 1801

Smith-Vaniz, William F. & Walsh, Stephen J., 2019, Indo-West Pacific species of Trachinotus with spots on their sides as adults, with description of a new species endemic to the Marquesas Islands (Teleostei: Carangidae), Zootaxa 4651 (1), pp. 1-37 : 27

Key to Indo-West Pacific species of Trachinotus

1a One to seven dark spots on or near lateral line (spots usually absent in specimens smaller than about 10–15 cm FL); segmented dorsal-fin rays 20–26; anal-fin pterygiophores inserting in first interhemal space typically 3 ( Fig. 1 , Table 1 )............ 2

1b No spots on or near lateral line at any size; segmented dorsal-fin rays 18–20 (except 21–23 in T. africanus ); anal-fin pterygiophores inserting in first interhemal space typically 2........................................................ 5

2a Adults with black spots in fresh specimens; no large spot above pectoral fin in adults............................... 3

2a Adults with silvery-gray spots in fresh specimens; 1 or 2 large spots above pectoral fin in adults....................... 4

3a Largest spot on side of adults usually smaller than or approximately size of iris diameter; adults with 2-6 spots (usually 3) spots on sides; height of dorsal-fin lobe 18.9–46.0% FL, mean 28.9%, in specimens> 200 mm FL (broadly distributed in Indo-West Pacific)..................................................................................... T. baillonii

3b Largest spot on side of adults distinctly larger than iris diameter; adults typically with 1 or 2 spots on side; height of dorsal-fin lobe 16.1–21.5% FL, mean 18.1%, in specimens> 200 mm FL (Marquesas Island endemic)............... T. macrospilus

4a Adults typically with only one spot above pectoral fin; vomerine tooth patch consistently round or triangular-shaped; segmented dorsal-fin rays 22–24, usually 22 or 23; segmented anal-fin rays 19–22, rarely 22 (Indian Ocean including Western Australia)...................................................................................... T. botla

4b Adults with two spots above pectoral fin; vomerine tooth patch usually chevron shaped; segmented dorsal-fin rays 23–25, usually 24 or 25; segmented anal-fin rays 22–24 (Eastern Australia, Lord Howe and Norfolk islands)........... T. coppingeri

5a Segmented dorsal-fin rays 21–23; segmented anal-fin rays 19–21; axillary base beneath pectoral fin often with black ring-like blotch (Western Indian Ocean, Gulf of Oman and Bali)............................................... T. africanus

5b Segmented dorsal-fin rays 18–20; segmented anal-fin rays 16–18; axillary base beneath pectoral fin without black ring-like blotch.............................................................................................. 6

6a Supraoccipital bone of skull becoming broad and sausage-shaped in adults ( Fig. 19A ), this character easily observed by simple dissection along midline of skull; in life, anal-fin yellow; teeth in narrow band on tongue, persisting to about 50 cm FL (Persian Gulf, Pakistan, India, China and southern Japan)................................................... T. mookalee

6b Supraoccipital bone of skull thin and blade-like in adults ( Fig. 19B ); in life, color of anal fin variable, yellow or brownish with orange anterior margin; tongue toothless (except 2 or 3 slender teeth rarely present in small specimens of T. blochii )...... 7

7a Supraneural bone a swollen inverted tear-drop, becoming oval-shaped in large adults ( Fig. 20 ); in life, anal-fin lobe brownish with anterior margin orange; nasal bone not swollen in adults (broadly distributed in Indo-West Pacific).......... T. blochii

7b Supraneural bone not swollen as above, shaped like an inverted “L” with the short arm projecting anteriorly; in life, anal-fin lobe yellow; nasal bone greatly swollen (hyperostotic) in adults (Eastern and northern Australia, South China Sea and southern Japan)......................................................................................... T. anak

Figures

FIGURE 1. Anterior part of anal fin of Trachinotus macrospilus (ANSP 153724) with 3 pterygiophores in first interhemal space. Abbreviations: As, anal-fin spines; Apt1, first anal-fin pterygiophore; Hs, haemal spines; IHS1, first interhaemal space. Photograph by Zachary S. Randall.

FIGURE 19. Dorsal and lateral views of skull in Trachinotus: A, T. mookalee, ANSP 148969, 570 mm FL, Cochin, India; B, T. africanus, ANSP 148968, 532 mm FL, Durban, South Africa (supraoccipital shape is the same in all species, except T. mookalee). Drawn by William F. Smith-Vaniz.

FIGURE 20. Hyperostotic first supraneural (shaded) and adjacent non-hyperostotic supraneural in lateral view (anterior to left). Outlines traced from radiographs plotted against fork length (FL) in Trachinotus blochii. Numbers correspond to the following specimen voucher catalog numbers, FL mm lengths (in parentheses) and localities: 1, CAS 32093 (130) Madagascar; 2, ANSP 148749 (160) Madagascar; 3, ANSP 148749 (178) Madagascar; 4, ANSP 148740 (190) Sri Lanka; 5, ANSP 144395 (212) Sri Lanka; 6, ANSP 148735 (229) Chagos; 7, ANSP 151014 (237) Sri Lanka; 8, ANSP 151015 (246) Sri Lanka; 9, ANSP 151015 (291) Sri Lanka; 10, ANSP 148735 (329) Chagos; 11, ANSP 138159 (335) Seychelles; 12, ANSP 138159 (364) Seychelles; 13, ANSP 148735 (407) Chagos; 14, ANSP 138157 (461) Seychelles; 15, ANSP 148733 (469) Sri Lanka; 16, ANSP 148735 (483) Chagos; 17, ANSP 148787 (520) Sri Lanka; 18, ANSP 138883 (556) Gulf of Oman.