Symphysanodon

William D. Anderson, Jr. & Victor G. Springer, 2005, Review of the perciform fish genus Symphysanodon Bleeker (Symphysanodontidae), with descriptions of three new species, S. mona, S. parini, and S. rhax., Zootaxa 996, pp. 1-44 : 4-6

Key to the species of Symphysanodon

In the key, unless otherwise noted, scale counts are of numbers of tubed lateral-line scales (excluding any that are posterior to the base of the caudal fin), gillraker counts are of total numbers on the first gill arch (including rudiments, if present), and sums of scales plus gillrakers are based on single counts of each character from each specimen examined.

1a. Scales 60 or 61. Gillrakers 41 or 42. Sum of scales plus gillrakers 102-both sides. (Based on holotype only)...................................... S. andersoni , western Indian Ocean

1b. Scales 55 or fewer. Gillrakers 24-42, usually fewer than 40. Sum of scales plus gillrakers on individual specimens 71-94 ........................................................................ 2

2a. Depth of body 2.8-3.1 times in SL (32-36% SL). Segmented rays in anal fin usually 8, occasionally 7. Gillrakers 38-42. Scales 45-48. Formula for configuration of supraneural bones, anterior neural spines, and anterior dorsal pterygiophores 0/0/0 + 2/ 1 + 1/1/. Hypurals 3 & 4 autogenous ........... S. octoactinus , western Atlantic Ocean

2b. Depth of body 3.0-5.0 times in SL (20-33% SL, usually less than 30% SL). Segmented rays in anal fin 7 (very rarely 6). Gillrakers 24-40. Scales 42-55. Formula for configuration of supraneural bones, etc., almost always 0/0/0 + 2 + 1/1/1/, never 0/ 0/0 + 2/1 + 1/1/. Hypurals 3 & 4 represented by a single plate..................................3

3a. Gillrakers 24 or 25 (4 or 5 on upper limb) ............................... S. mona , new species, Mona Passage off Puerto Rico, western Atlantic Ocean

3b. Gillrakers 29-40 (9-12 on upper limb)........................................................................ 4

4a. Anal fin long, length of depressed anal fin 2.6-2.9 times in SL (34-39% SL). Depth of body 3.2-3.7 times in SL (27-31% SL). In fresh specimens yellow or orange band visible on side of body extending to or almost to caudal-fin base............ S. katayamai , western and central Pacific Ocean

4b. Anal fin short, length of depressed anal fin 2.9-4.5 times in SL (22-34% SL, a specimen of S. maunaloae with anal fin 37.0% SL). Depth of body 3.0-5.0 times in SL (20-33% SL), 270 of 276 specimens (98%) examined with depth of body more than 3.4 times in SL (less than 29% SL). Side without yellow or orange band................. 5

5a. Scales 42-50. Gillrakers 29-39. Sum of scales plus gillrakers on individual specimens73-85 .................................................................................................................. 6

5b. Scales 48-55. Gill rakers 34-40. Sum of scales plus gillrakers on individual specimens83-94 .................................................................................................................. 7

6a. Scales 42-47 (mean = 44.94). Pectoral-fin rays 15-17 (mean = 16.13). Least depth of caudal peduncle 10-13% SL. Length of third anal-fin spine 13-16% SL. Length of second anal-fin spine 11-15% SL .......................................................... S. maunaloae , widely distributed, from French Polynesia and the Hawaiian Islands westward through the Pacific to the Philippines and Indonesia and apparently to the Strait of Malacca

6b. Scales 45-50 (mean = 47.89). Pectoral-fin rays 16-18 (mean = 16.90). Least depth of caudal peduncle 9-10% SL. Length of third anal-fin spine 12-13% SL. Length of second anal-fin spine 10-12% SL .............................................. S. parini , new species, Sala y Gómez Ridge, eastern South Pacific Ocean

7a. Length of anal-fin base 15-21% SL. Length of depressed anal fin 27-34% SL. Length of first anal-fin spine 4.8-7.2% SL. Scales 49-55. Gillrakers 36-40. Sum of scales plus gillrakers of individual specimens 86-94. Pectoral-fin rays 15-18, most frequently 16 (rarely 18). First segmented ray of pelvic fin only slightly produced, usually not extending to origin of anal fin. Caudal-fin lobes produced, but apparently never produced into extremely long filaments. Hypurals 1 & 2 represented by a single plate. Parapophyses present on first caudal vertebra ........................................ S. typus , widely distributed in the Pacific Ocean from the Hawaiian Islands (in the north) and Wallis and Futuna (in the south) to the Philippines and Indonesia

7b. Length of anal-fin base 13-16% SL. Length of depressed anal fin 22-30% SL. Length of first anal-fin spine 3.0-5.6% SL. Scales 48-52. Gillrakers 34-39. Sum of scales plus gillrakers of individual specimens 83-90. Pectoral-fin rays 16-18, usually 17. First segmented ray of pelvic fin noticeably produced in males longer than ca. 85 mm SL, extremely filamentous in large individuals -occasionally reaching past fork of caudal fin. Caudal-fin lobes frequently produced into extremely long filaments in large males of S. berryi (caudal-fin lobes damaged in all specimens of S. rhax examined). Hypurals 1 & 2 autogenous. Parapophyses absent from first caudal vertebra .......... 8

8a. Length of second anal-fin spine 9.9-13.4% SL. Width of bony interorbital 7.2-9.0% SL. Least depth of caudal peduncle 9.5-11.9% SL ......................................... S. berryi , western, central, and eastern Atlantic Ocean

8b. Length of second anal-fin spine 7.5-9.2% SL. Width of bony interorbital 6.6-7.3% SL. Least depth of caudal peduncle 7.1-9.7% SL ........................ S. rhax , new species, northern Indian Ocean off the Maldive Islands

Description of characters shared by the three new species of Symphysanodon

Because Symphysanodon mona , S. parini , and S. rhax are morphologically similar, it is appropriate to characterize them under a single heading and then to elaborate as necessary under the respective species accounts.

Snout relatively blunt. Anterior ends of premaxillae incised, forming a notch that receives the anterior ends of the dentaries. Dorsalmost margin of maxilla covered by very narrow suborbital with mouth closed. Mouth terminal; lower jaw inclined dorsally with mouth closed; jaws about equal. Maxilla reaching posteriorly to a vertical through middle of eye or to well beyond middle of eye. Anterior and posterior nares fairly closely set on each side of snout. Pseudobranchiae present. Interorbital region flattened. Premaxillae and dentaries with small teeth. Premaxillary teeth somewhat larger anteriorly; premaxillary notch toothless. Dentary with teeth extending from elevated posterodorsal surface of jaw almost to symphysis; usually a few larger teeth at anterior ends of dentaries fit into premaxillary notch with mouth closed; symphysis toothless. Vomer, palatines, pterygoids, and tongue (tongue not observed in S. mona , having been dissected away) apparently edentate (any teeth present on those structures are extremely small). Opercle with two flattened spines, the ventral one longer and better developed. Numerous small serrae on vertical limb of preopercle; usually a few larger serrae on horizontal limb; a spine or spinelike process at angle of preopercle. Dorsal fin continuous and not incised at junction of spines and segmented rays. Scales ctenoid (with ctenial bases in the posterior field proximal to marginal cteni -see Hughes, 1981; this is the transforming ctenoid scale of Roberts, 1993). Most of head, including maxillae, dentaries, lachrymals, and interorbital region with scales; much of dorsal aspect of snout without scales; lateral aspects of snout with or without scales. Dorsal and anal fins without scales, but with scaly sheaths at their bases. Large modified scales associated with pelvic fin, just dorsal to pelvic spine (axillary scales) and in ventral midline between the pelvic fins (interpelvic scales). Lateral line gently curved beneath dorsal fin. Caudal fin well forked.

Branchiostegals 7. Anal-fin rays III, 7. Pelvic-fin rays I, 5. Principal caudal-fin rays 17 (9 + 8); branched rays 15 (8 + 7). No spur on posteriormost ventral procurrent caudalfin ray, but penultimate ventral procurrent caudal-fin ray shortened basally (see Johnson, 1975). Vertebrae 25 (10 precaudal + 15 caudal). Formula for configuration of supraneural bones, anterior neural spines, and anterior dorsal pterygiophores 0/0/0 + 2 + 1/1/1/. Pleural ribs on vertebrae 3 through 10. First caudal vertebra without parapophyses. Short neural spine on second preural centrum. Autogenous haemal spine associated with second preural centrum. Parhypural autogenous, bearing a hypurapophysis. Hypurals 1 and 2 autogenous; 3 and 4 represented by a single plate, probably representing an ontogenetic fusion (based on unpublished studies by G. David Johnson of larvae of other species of Symphysanodon ). Hypural 5 autogenous. Epurals 3.