Myxodes viridis Valenciennes 1836

Carnivore (Ref. 50629).

Juveniles feed on copepods and shifts to diet of amphipods in adults.

Myxodes viridis Valenciennes

Myxodes viridis Valenciennes in Cuvier and Valenciennes, 1836:398 [coast of Chile; holotype, MNHN A. 4139].

Myxodes ocellatus Valenciennes in Cuvier and Valenciennes, 1836: 400 [Valparaiso; holotype, MNHN A.1705].

Myxodes schmitti Hubbs, 1952:109 [Independencia Bay, Peru; erroneously reported as Santa Cruz Island, Galapagos Islands in original description; holotype, USNM 102008].

Hubbs (1952) first synonymized M. ocellatus with M. viridis but gave no reason for his action. We have examined the holotypes of both species and agree with Hubbs’ action. The color pattern differences upon which Valenciennes distinguished the two species are representative of normal variations encountered in a single collection.

Hubbs described M. schmitti from the erroneous type-locality of Santa Cruz Island, Galapagos. The locality was corrected to Independencia Bay, Peru, by Springer (1970). Hubbs reported that M. schmitti had a longer head (approximately 20 percent SL) and deeper body (approximately 22 percent SL) than M. viridis (head length and body depth both supposedly approximately 17 percent SL). Our methods must be different from Hubbs’, for we find that head length ranges from 20.5–22.2 percent SL and body depth 19.1–20.9 percent SL in specimens of M. viridis, including the holotype of M. schmitti. We therefore find no reason to maintain M. schmitti.

DESCRIPTION.—Salient specific characters are presented in the key. Dorsal fin XXXIV–XXXVI (35.1), 6–7 (6.4); total dorsal-fin elements 41–43; anal fin II, XXXIV–XXXVI 24–25 (24.2); pectoral fin 11–12 (12); pelvic fin I, 3; caudal fin 11–13 (12); vertebrae 16–18 + 31–34 = 48–51.

Morphometric characters of eleven specimens examined: SL 46.1–127.0 mm, head length 20.5–22.2, head depth 14.2–15.7, head width 10.9–12.6, upper-jaw length 6.7–8.1, eye diameter 4.6–5.7, snout length 4.7–6.9, interorbital width 2.7–3.4, predorsal length 14.8–16.6, preanal length 39.7–45.0, body depth 19.1–20.9, caudal-peduncle length 9.1–12.9, caudal-peduncle depth 5.7–6.6, length first dorsal-fin spine 4.6–7.3, length fourth dorsal-fin spine 4.6–6.0, distance between dorsal-fin spines three and four 3.3–4.5, distance between dorsal-fin spines one and three 3.2–4.7, pectoral-fin length 12.3–17.0, pelvic-fin length 9.5–11.6, length inner pelvic-fin ray 6.7–9.3, orbital-cirrus length 1.0–1.6, nasal-cirrus length 0.9–1.3.

SPECIES COMPARISON.—Myxodes viridis is similar to M. cristatus in total number of median-fin rays and vertebrae as well as number of mandibular and supraorbital sensory pores. The two species differ from each other in color pattern, number of dorsal-fin spines, segmented dorsal- and anal-fin rays (Table 2), orbital-cirrus length, first dorsal spine length (Figure 5), caudal-peduncle length (Figure 6), and interorbital width (Figure 7). DeBuen (1962) gives higher pectoral-fin ray counts (13–14) for C. viridis than any we have found. All our specimens of M. cristatus and the majority of our specimens of M. viridis, including the holotypes, have 12 pectoral-fin rays; 11 rays were only found in 2.8 percent of our specimens of M. viridis.

Early in our study of Myxodes we thought that M. cristatus and M. viridis represented males and females of a single dimorphic species. All our sexed specimens (N = 8, the types were not sexed) of M. cristatus are males, and all but one of our specimens of M. viridis are either females or immature (N = 66: 5 ♀ ♀, 1 ♂, 60 immature). The fact that both M. cristatus and M. ornatus are known only from a single sex may indicate that the sexes are segregated, possibly in their depth distributions, as suggested by Williams (1954) for the myxodinine genus Gibbonsia.

DISTRIBUTION.—All three species of Myxodes were taken in the same collection (SI0 65–678) at La Ventana, Chile. Myxodes viridis occurs north at least to Independencia Bay, Peru, and on the basis of our collections does not occur south of Valparaiso. Myxodes cristatus, on the other hand, is known to occur only from La Ventana south, our most southern record being Puerto Auchemo (43°01′ south latitude). It appears, therefore, that M. viridis and M. cristatus are largely allopatric.

MATERIAL EXAMINED.—Chile: Valparaiso, MNHN A–4139 (holotype of M. viridis, 125); La Ventana, SI0 65–678 (57:43–128), USNM 205104 (3:53–95), USNM 208072 (1:74); Vina del Mar, UCLA 66–58 (1:65); Montemar, USNM 200673 (2:58–92); Coast of Chile, MNHN A–1705 (holotype of M. ocellatus, 123); Peru, 14°16′ south latitude, USNM 203558 (1:42); Independencia Bay, USNM 102008 (holotype of M. schmitti, 146).

Myxodes viridis is a species of clinid native to the Pacific coast of South America from southern Peru to central Chile. This species can reach a maximum length of 13.5 centimetres (5.3 in) TL.