Ophidion galapagensis Lea & Robins, 2024

Lea, Robert N. & Robins, C. Richard, 2024, Description of a new species of cusk-eel (Teleostei, Ophidiiformes, Ophidiidae, Ophidion) from the Galápagos Archipelago and Isla del Coco, long known but previously undescribed, Zootaxa 5497 (2), pp. 292-298 : 293-296

Ophidion galapagensis Lea & Robins new species urn:lsid:zoobank.org:act:B2D45C8B-7527-427A-B483-E03F100964AB

Galapagos Cusk-eel

Chilara taylori Snodgrass & Heller, 1905 .

Ophidion sp. Humann, 1993. [“sp.” in italics by Humann; note added here for clarification, “sp.” should not be in italics when referring to this name].

Ophidion species. Grove & Lavenberg, 1997.

Ophidion sp. A . Grove et al., 2022.

Material Examined: Holotype LACM 61409, 142.5 mm SL, 1 of 13 specimens, originally as LACM 43689-1 . Figure 1 . Galápagos Archipelago, Wenmen Island ( Wolf Island ), collected by ichthyocide, 21–23 m, 15 May 1984 . Paratypes: CAS 247364 , 3 : 25.0– 34.5 mm SL, Tower Island , 3–8 m, 10 Mar. 1977 ; LACM 43680-1 , 12 : 51–128.3 mm SL, taken with holotype, Wenmen Island , 21–23 m, 15 May 1984 ; LACM 33646-14 , 1 : 107 mm SL, Isla del Coco , north of Manuelita Island, 110 m, 2 Jun. 1973 ; LACM 43975-8 , 1 : 63.0 mm SL, Isabella Island , Tagus Cove, 6–14 m, 28 Nov. 1983 ; MCZ 40433 , 2 : 124.5–171.5 mm SL, Baltra Island , 1958 . USNM 214094 , 1 : 90.3 mm SL, Fernandina Island , 10–25m, 25 May 1966 ; USNM 214095 , 1 : 74.1 mm SL, Isabella Island , NW of Tagus Cove, 1–15 m, 24 May 1966 .

Additional material: CAS-SU 6403, 1: ca. 65 mm TL, Albemarle Island, 1898-99, “ Chilara taylori ” of Snodgrass & Heller (1905); CAS 50103, 1: 45.7 mm TL, Santiago Island, James Bay, 25 m, 9 Jul. 1969; USNM uncat., 3: 57.6–62.2 mm, Isla Fernandina, 16–20 m, 3 Apr. 1990.

Otophidium indefatigabile : LACM 33645-2 , 3 : 56–78 mm SL, Isla del Coco, 91 m, 2 Jun. 1973; LACM 33646-2 , 19 , 49–117 mm SL, Isla del Coco, 110 m, 2 Jun. 1973; LACM 33647-3 , 4 : 63–115 mm SL, Isla del Coco , 128 m, 2 Jun. 1973; LACM 33648-1 , 1, 113 mm SL, Isla del Coco , 174 m, 2 Jun. 1973; UCR 711-17 , 1 : 42 mm SL, Isla del Coco , 31 Mar. 1972; USNM 44393 , Holotype, 1: 96.5 mm SL, Galápagos Archipelago , Indefatigabile Island , Apr. 1888.

Diagnosis.

A member of the genus Ophidion distinguished from congeners by the following combination of characters: Dorsal-fin rays 141–154 (162, MCZ 40433), anal-fin rays 115–123 (131, MCZ 40433). Vertebrae: 16–18 precaudal, 55–58 caudal, 72–75 total. Pectoral-fin rays 24–25, outer pelvic filaments long, exceeding pectoral length; pectoral fin approximately 60% pelvic-fin length. Gill rakers on first arch 6, 2 reduced rakers on upper limb and 4 developed rakers of moderate and equal length on lower limb; caudal-fin rays 4/5=9; branchiostegals 7.

Description. A narrow-bodied ophidiine cusk-eel, of medium size, known to 172 mm SL. Scales ovoid, anguilliform arrangement on body; head naked; ethmoid process not developed into spine, blunt to touch; pyloric caeca lacking.

Dorsal-fin rays 141–162, anal-fin rays 115–131. Vertebrae: 16–18 precaudal, 55–58 caudal, 72–75 total. Pectoral-fin rays 24–25; gill rakers on first arch 6, 2 reduced rakers on upper limb and 4 developed rakers of moderate and equal length on lower limb; caudal-fin rays 4/5=9; branchiostegals 7.

Outer pelvic filaments long, exceeding pectoral length; pectoral fin approximately 60% pelvic-fin length. Pelvic filaments of unequal length, outer branch about 1.5–1.6 inner. Head length 19–22% SL. Pectoral fin relatively short, 37–48% of head length.

Teeth on premaxilla, palatine, vomer, and dentary, in several series on each bone. Snout overlapping lower jaw. Mouth directed forward. Lateral line incomplete, 82–93% SL. Orobranchial chamber pale. Esophagus blackish; foregut, stomach, and hindgut not pigmented. Sub-nasal flaps slightly developed, extend onto premaxilla. Swim bladder in males large and jug-like with posterior constricted membrane-covered opening, filling forward half of body cavity, shorter and simpler in females. Rocker bone absent.

Meristic data summarized in Table 1 . Body proportions (with measurements given in hundredths of SL) in Table 2 .

Coloration. The authors have not examined fresh specimens. A brief, fragmented description comes from Humann (1993) who also provides a color photograph. Color from Humann (1993): “Four long white barbels under chin [...] Shades of gray to brown; can pale or darken.” Constant (2007) illustrates two cusk-eels (Photos 179 and 180), both of which are Ophidion galapagensis , in his guide to the marine life of the Galápagos. Photo 179 is mislabeled as a “Blackfin Conger, Paraconger californiensis ,” however, it is an excellent example of a cusk-eel emerging from the sand and shows the plain coloration typical of the new species, including the black edging on the dorsal fin. Photo 180, labeled as Galápagos brotula, Ophidion sp. (E), shows a cusk-eel resting over mixed sand substrate. In May 1992, two 35 mm slides were received from Peter L. Haaker, who had completed a diving trip to the Galápagos Archipelago in August 1990. The images showed a cusk-eel photographed on a night dive at Point Vicente Rock, Isabella Island. Depth was “ 30 to 50 feet [ca. 9 to 15 meters], probably closer to the former,” with the fish swimming over a sandy bottom. The coloration of the fish was noted as plain and tannish, i.e., sand colored ( Fig. 2 ). Color in alcohol, uniformly light tan. Dorsal fin with a narrow black margin normally terminating short of caudal fin.

Size. Ophidion galapagensis is a medium-size ophidiine cusk-eel. The largest specimen examined measured 171.5 mm SL and 173.1 mm TL.

Etymology. Name is in reference to the Galápagos Archipelago and treated herein as a noun in apposition. We propose Galapagos Cusk-eel as the common name.

Distribution. Endemic to the Galápagos Archipelago and the outlying Isla del Coco.

Comparisons. Of the seven described species of eastern Pacific ophidiine cusk-eels, five are patterned and thus not likely to be confused with O. galapagensis : Chilara taylori , Ophidion fulvum Hildebrand & Barton, 1949 , O. galeoides ( Gilbert, 1890) , O. imitator Lea, 1997 , and Otophidium indefatigabile . Ophidion iris Breder, 1936 and O. scrippsae ( Hubbs, 1916) are the two non-patterned species. Ophidion iris is restricted to the lower two-thirds of the Gulf of California with an isolated population at Islas Tres Marías. Ophidion scrippsae is a warm-temperate (San Diegan Province) species and occurs from the Point Conception biogeographic boundary ( Miller 2023) south to Magdalena Bay, Baja California Sur, Mexico.

Figures

FIGURE 1. Ophidion galapagensis photographed shortly after capture, at Wenmen Island, 15 May 1984, by Jack S. Grove.

FIGURE 2. Ophidion galapagensis photographed on night dive at Isabella Island, August 1990, “depth 30 to 50 feet,” by Peter L. Haaker.