Porogadus atripectus Garman, 1899

Schwarzhans, Werner W. & Møller, Peter R., 2021, Revision of the ‘ dragon-head’ cusk eels of the genus Porogadus (Teleostei: Ophidiidae), with description of eight new species and one new genus, Zootaxa 5029 (1), pp. 1-96 : 25-28

Porogadus atripectus Garman, 1899

Figs. 7–8 , 44 , 49 , Tab. 1–7

Porogadus atripectus Garman, 1899: 154 , pl. 37, fig. 3; Nielsen et al. 1999: 86; Castellanos-Galindo et al. 2006:198.

Material examined (30 specimens): MCZ 28657 (lectotype), 253 mm SL, off Pacific Panama, 05°30’N 86°45’W, 1951 m , R / V Albatross, large beam trawl, 27 February 1891 ; MCZ 28656 (paralectotype), Gulf of Panama, 07°05’30”N 79°40’W, 2322 m , R / V Albatross, large beam trawl, 10 March 1891 ; MCZ 28658 (paralectotype), 193 mm SL, off Mexico, 16°34’N 100°03’W, 1229 m , R / V Albatross, small beam trawl, 11 April 1891 ; LACM 36550-5 (3 specimens), 233–258 mm SL, off California , R / V Velero IV, IKMT Isaacs-Kidd Midwater Trawl, 26 January 1977 ; SIO 61-175 (3 specimens), 130–268 mm SL, Cabo San Lorenzo , 23°07’N 113°15’W, 3515 m, 10-ft beam trawl , RV Spencer F Baird, collected by Mr. Parker, 3 May 1961 ; SIO 68-82 (5 specimens), 110–225 mm SL, Guaymas Basin , 27°12’N 111°25’W, 1875 m , R / V Thomas Washington, sta. MV 68 -I-49, 41-ft ballon trawl, collected by Carl L. Hubbs & party, 15–16 January 1968 ; SIO 70-248 (2 specimens), 198–216 mm SL, Guaymas Basin , 27°16’N 111°25’W, 1880 m, Operation Blind Spot, 25-ft otter trawl, collected by R. McConnaughey, 14 Jun 1970 ; SIO 70-249 (2 specimens), 185+ and 227 mm SL, Guaymas Basin , 27°17’N 111°26’W, 1875 m, Operation Blind Spot, 25-ft otter trawl, collected by R. McConnaughey, 15 Jun 1970 ; SIO 81-148 (2 specimens), 260 mm SL, Panama Basin , 5°10.5‘N 81°40.8‘W, 3900–4000 m , R / V Melville, 40-ft otter trawl, collected by R. Wilson, 3 October 1931 ; SIO 89-108 (1 specimen), 225 mm SL, San Clemente Basin , 32°36’N 118°10’W, 1500–1940 m , R / V Robert Gordon Sproul, collected by R. Kaufman, 12 September 1989 ; USNM 405735 (9 specimens), 169–277 mm SL, 04°17’S 81°44’W, 1815–1860 m , R / V Anton Bruun, Cruise 18B, Sta. 766, 72 ft shrimp trawl, collected by L.W. Knapp, 9 September 1966 .

Diagnosis. Precaudal vertebrae 17–18; long gill rakers on first gill arch 15–18; HL:HD 1.6–1.8 (rarely 1.52– 1.6); head spines strong on ethmoidal, sphenotic, outer posttemporal, inner preopercular rim, weak on lacrimal, prefrontal, interorbital, 5th infraorbital, absent on supraorbital, supratemporal, and outer preopercular rim; opercular spine flat, weak; lower lateral line pores until beginning of anal fin 17–20; vomer with broad dentition patch (2–4 rows); palatines with broad dentition patch (5–7 rows); otolith with single colliculum and step at collum; OL:OH = 1.45–1.65.

Description. Meristics: precaudal vertebrae 18 (17–18), 0 (0–2) last vertebrae without ribs; pectoral-fin rays 20 (16–20); D/V = 5 (5–7); D/A = 28 (24–29); V/A = 19 (18–20); long gill rakers on lower gill arch 16 (15–18). Gill rakers in a paralectotype (MCZ 28658) on lower first gill arch with seven plate-shaped rakers, followed by a series of 17 long rakers. The lower 13 of those intercepted by single plate shaped rakers. Upper gill arch with a series of three five plate shaped rakers intercepted by three slightly longer rakers.

Morphometrics: in % of SL: HL 15.8 (14.7–17.6); maximal HD 9.2 (8.8–10.6); HD through center of eye 5.8 (5.6–7.3); bony interorbital width 3.9 (3.0–4.1); snout length 5.3 (4.7–5.7); upper jaw length 9.4 (8.6–10.9); predorsal 17.2 (15.5–19.1); preanal 31.2 (30.3–35.4); prepelvic 13.4 (11.3–14.5); prepectoral 15.6 (15.0–17.6); pectoral length 7.4 (7.4–10.4). Relations: HL:HD = 1.71 (1.61–1.80, rarely down to 1.52); HL to snout length 2.96 (2.78–3.25); preanal to predorsal 1.82 (1.65–2.01); predorsal to prepectoral 1.10 (1.03–1.16).

Slender fish with long tapering tail and moderately pointed snout. Maximal size of fishes investigated 277 mm SL. Head moderately long and slender, with straight or slightly concave dorsal profile, with mostly weak spines as follows: 1 strong spine on ethmoidal, 2–3 strong spines along sphenotic, 1–2 strong spines on outer posttemporal, 3–4 spines along inner preopercular rim, narrow ridge on lacrimal, 1 weak spine on prefrontal, 2 weak spines on interorbital, no or 1 spine on 5th infraorbital, no spines on supraorbital, supratemporal, and along outer preopercular rim. Opercle with flat, weak, poorly extruding spine. Eye small located in strongly asymmetric orbit. Maxilla extending far beyond eye, strongly widened posteriorly and with distinct supramaxilla. Infra-/postorbital and mandibular-preopercular pores wide, pores on occiput in front of nape. Head squamation on opercle, cheeks and occiput, small scales surrounding eye, no scales on snout and maxilla ( Garman 1899 shows scales on maxilla). Opercle with two distinct large neuromasts behind preopercular edge; opercular flap small, with or without radial ridges, completely covered with scales. All three lateral line rows well visible. Upper lateral line row with 9–12 pores; lower lateral line row with 17–20 pores until beginning of anal fin; central lateral line row long, lower and central lateral line rows fading behind beginning of anal fin.

Dentition. All teeth tiny and cone-shaped. Vomer with a v-shaped dentition patch with 2–4 rows of teeth anteriorly; palatines with a long and moderately wide dentition patch with 5–7 rows. Premaxilla tooth patches not fused anteriorly; ca. four teeth rows anteriorly and 1–2 rows posteriorly. Dentary tooth patches not fused anteriorly; ca. four teeth rows anteriorly and one row posteriorly. Median basibranchial tooth patch short to moderately long and wide, rarely with single tiny lateral patch.

Otolith morphology (n = 2). Size up to 4.4 mm in length; OL:OH = 1.45–1.65; OH:OT c. 2.5. Thin, oval, moderately elongate otolith, anteriorly rounded, posteriorly slightly tapering. Dorsal rim with obtuse angle in front of middle; ventral rim shallow, regularly curving. All rims smooth. Inner face nearly flat, smooth, with short, centrally positioned sulcus; OL:TCL = 2.4. Sulcus with shallow, undivided colliculum showing step in shape along ventral margin at collum.

Coloration. Live coloration not known. Color of preserved specimens light to medium brown; pectoral fin slightly darker; head darker than body, particularly opercle.

Discussion. Porogadus atripectus differs from all other species of the Porogadus miles Group in the less slen- der head (HL:HD ≤ 1.8 vs> 1.8), and the flat and weak opercular spine. Also, the head spines are generally less and weaker in many cases than in other species of the Porogadus miles Group. Because of the less slender head shape, P. atripectus resembles fishes of the Porogadus trichiurus Group but differs from them in the lower number of long gill rakers (15–17, rarely 18 vs 18–21, except 16–17 in P. solomonensis n. sp.), the longer preanal (30.3–35.4 vs 26.7–30.0), and the presence of scales on frontal, occiput and around eye (vs no scales on frontal, occiput and around eye, except on occiput in P. trichiurus ). Because its relatively weak head spines P. atripectus also resembles the species of the Porogadus gracilis Group but differs in the presence of spines along the inner margin of the preopercle (vs absent), the scales around the eye (vs absent), and the larger and more elongate otolith (OL:OH = 1.45–1.65 vs 1.15–1.25). It thus appears that P. atripectus stands somewhat isolated from the other members of the Porogadus miles Group and morphologically somewhat intermittent to the Porogadus trichiurus and Porogadus gracilis groups.

Distribution. Porogadus atripectus is endemic to the East Pacific off the shores of America from 32°N to at least 04°S ( Fig. 44 ). It has been caught mostly between 1800 and 4000 m, rarely up to 1200 m on the lower reaches or the base of the continental slopes. There does not appear to be a relationship of fish sizes with depth of occurrence. Porogadus atripectus does not appear to venture away from the slope for more than about 500 km ( Fig. 50 ).

Figures

FIGURE 7. Porogadus atripectus Garman, 1899; LACM 36550-5, off California; 7A–B, 258 mm SL; 7C, 233 mm SL.

FIGURE 8. Porogadus atripectus Garman, 1899; 8A–B, SIO 89-108, 225 mm SL, 32°36’N, 118°10’W, 1500–1940 m, head drawings; 8C–D, USNM 405735, 236 mm SL, 04°17’S, 81°44’W, 1815–1860 m, head drawings; 8E–F, MCZ 28657, lectotype, 253 mm SL,05°30’N, 86°45’W, 1951 m, otolith (E inner face, F ventral view).

FIGURE 44. Geographic distribution of the species of the Porogadus miles group.

FIGURE 49. Depth versus distance from shelf plots for specimens of the Porogadus miles group (upper panel) and the Porogadus gracilis group (lower panel).

FIGURE 50. Depth versus distance from shelf plots for specimens of the Porogadus trichiurus group (upper panel) and the Porogadus catena group (lower panel).