Symphysanodon rhax Anderson & Springer, 2005, new species

• Main Authors: William D. Anderson, Jr., Victor G. Springer
• Format: Other/Unknown Material
• Language: unknown
• Published: 2005
• Subjects: Biodiversity; Taxonomy; Animalia; Chordata; Actinopterygii; Perciformes; Symphysanodontidae; Symphysanodon; Symphysanodon rhax; Indian; Fridtjof; Fridtjof Nansen
• Online Access: https://zenodo.org/record/6266866; https://doi.org/10.5281/zenodo.6266866

Symphysanodon rhax, new species Maldives Slopefish (Figures 9-15; Tables 4, 5, 8, 9) Holotype: BMNH 2003.1.5.1, 144 mm SL; Maldive Islands, northern Indian Ocean; 04°11’ N, 72°55’ E; 218 m; R/V DR FRIDTJOF NANSEN cruise: Maldives station no. 13; 21 August 1983. Paratype. BMNH 2003.1.5.2, 134 mm SL, from the same station as the holotype. Other specimens, not part of the type series. BMNH 1997.9.17:2, one specimen, 64 mm SL; R/V DR FRIDTJOF NANSEN survey of the Maldives, 04°05’ N, 73°23’ E - BMNH 1997.9.17:6-8, three specimens, 128-136 mm SL; R/V DR FRIDTJOF NANSEN survey of the Maldives, 04° 11’ N, 72°55’ E. Diagnosis. A species of Symphysanodon (Figure 10) separable from all other species of the genus, except S. berryi, by the following combination of characters: segmented rays in anal fin 7, tubed lateral-line scales 50, total gillrakers on first gill arch 35-38 (10 or 11 + 25-27), sum of lateral-line scales and gillrakers on individual specimens 85-88, depth of body 20.6-24.8% SL (4.0-4.9 times in SL), length of depressed anal fin 21.8-23.9 % SL, length of anal-fin base 12.6-14.8% SL, length of first anal-fin spine 3.0-4.8% SL, hypurals 1 & 2 autogenous, hypurals 3 & 4 represented by a single plate, and first caudal vertebra without parapophyses. It can be separated from the Atlantic species S. berryi by a number of morphometric characters (see Table 4 and Figures 11-15). It also differs slightly from S. berryi in counts of pectoral-fin rays (17 or18, mean = 17.33, for S. rhax vs. 16-18, mean = 16.99, for S. berryi). Description. The characters included in the combined description of S. mona, S. parini, and S. rhax and those presented in the species diagnosis form part of the species description. Counts for the holotype are indicated by asterisks. Dorsal-fin rays IX, 10.* Pectoral-fin rays 17 or 18*. Procurrent caudal-fin rays 13 or 14 dorsally, 12 or 13 ventrally. Trisegmental pterygiophores 2 or 3* associated with dorsal fin, 2 or 3 with anal fin. Epineurals associated with first 8* or 9 vertebrae ...