Comprehensive DescriptionRead full entry
Sala y Gómez Slopefish
(Figures 5-9; Tables 2, 3, 8, 9)
Symphysanodon maunaloae ZBK (non Anderson, 1970): Kotylar and Parin, 1990: 114, fig. 6 (eastern South Pacific, Sala y Gómez Ridge; otolith morphology and age).-Parin, 1990: 21 (eastern South Pacific, Sala y Gómez Ridge).-Parin et al., 1990: 46 (eastern South Pacific, Sala y Gómez Ridge; feeding and trophic relationships).-Parin, 1991: 679, table 1 (eastern South Pacific, Sala y Gómez Ridge).-Parin et al., 1997: 173 (eastern South Pacific, Sala y Gómez Ridge).
Holotype: USNM 372776, 114 mm SL; Sala y Gómez Ridge, eastern South Pacific; 25°04’ S, 97°28’ W; 240-275 m; R/V PROFESSOR MESYATZEV trawl 41; 4 October 1984.
Paratypes. USNM 375198, four specimens, 81-112 mm SL; IOAN uncatalogued, five specimens, 93-114 mm SL; all collected with the holotype.
Diagnosis. A species of Symphysanodon ZBK (Figure 5) separable from all other species of the genus, except S. maunaloae ZBK , by the following combination of characters: segmented rays in anal fin 7, tubed lateral-line scales 45-50, total gillrakers on first gill arch 31-34 (9 or 10 + 22-24), sum of lateral-line scales and gillrakers on individual specimens 77-84, depth of body 22.5-24.7 % SL (4.0-4.4 times in SL), length of depressed anal fin 24.8- 26.4 % SL, hypurals 1 & 2 autogenous, hypurals 3 & 4 represented by a single plate, and first caudal vertebra without parapophyses. It can be separated from S. maunaloae ZBK by differences in mean numbers of tubed lateral-line scales (mean = 47.89 for S. parini ZBK vs. mean = 44.94 for S. maunaloae ZBK ; see Table 2) and pectoral-fin rays (mean = 16.90 for S. parini ZBK vs. mean = 16.13 for S. maunaloae ZBK ; see Table 2) and by differences in certain morphometric characters (see Figures 6-8).
Description. The characters included in the combined description of S. mona ZBK , S. parini ZBK , and S. rhax ZBK 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, 9 or 10* (10 in 9 of 10 specimens). Pectoral-fin rays 16-18 (17*). Procurrent caudal-fin rays 13 or 14* dorsally, 12-14 (13*) ventrally. Trisegmental pterygiophores 2*-4 associated with dorsal fin, 2* or 3 with anal fin. Epineurals associated with first 8* or 9 vertebrae (first 8 vertebrae in 9 of 10 specimens). Uroneurals 2 pairs.* Internarial distance contained6-8 times in snout length. Other morphometric data are presented in percentages of SL in Table 3.
Comparisons of S. parini ZBK with other Pacific species of Symphysanodon ZBK . Symphysanodon parini ZBK can be distinguished from S. katayamai ZBK by its shallower body (depth of body 22-25 % SL vs. 27-31 % SL), shorter anal fin (length of depressed anal fin 25-26 % SL vs. 34-39 % SL), and smaller numbers of gillrakers (total on first gill arch 31-34 vs. 35-40) and lateral-line scales (45-50 vs. 50-52); from S. typus ZBK by its shorter anal fin (length of depressed anal fin 25-26 % SL vs. 27 ->34 % SL) and smaller numbers of gillrakers(total on first gill arch 31-34 vs. 36-40) and tubed lateral-line scales (45-50 vs. 49- 55); and from S. maunaloae ZBK by its larger mean numbers of tubed lateral-line scales (mean = 47.89 vs. mean = 44.94; see Table 2) and pectoral-fin rays (mean = 16.90 vs. mean = 16.13; see Table 2) and by its shallower caudal peduncle and shorter second and third anal -fin spines (see Figures 6-8).
Sexuality and sexual dimorphism. Histological examination of the gonads of all available specimens of S. parini ZBK showed that nine individuals (81-114 mm SL) are males and one (98 mm SL) is a female with no indication of hermaphroditism. In our limited sample size we found no evidence of sexual dimorphism. This contrasts with the situation in S. maunaloae ZBK which seems to show distinct differences between the sexes in lengths of pelvic fins and caudal-fin lobes (see below). The absence of obvious sexual dimorphism in external morphology may be an additional character distinguishing parini ZBK from maunaloae ZBK .
Distribution. Known only from the Sala y Gómez Ridge, eastern South Pacific (Figure9). The type specimens were collected in 240-275 m; Parin et al. (1997: 173) reported this species from depths of 240-300 m.
Etymology. We are pleased to name this species for N.V. Parin of the P. P. Shirshov Institute of Oceanology, Moscow, who provided the material on which the description is based and who has been of invaluable assistance to us and other ichthyologists for many years.