Porogadus catena ( Goode & Bean, 1885 )

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 : 67-71

Porogadus catena ( Goode & Bean, 1885)

Figs. 34–35 , 47 , 50 , Tab. 1–7

Bathyonus catena Goode & Bean, 1885: 603 , pl. 11 fig. A.

Bassozetus catena: Goode & Bean 1896: 323 , fig. 286; Jordan & Evermann 1898: 2509; Jordan & Evermann 1900: pl. 356, figs. 876, 876a.

Porogadus catena: Norman 1939: 87 ; Carter 1984: 2–183; Carter & Sulak 1984: 374, fig. 6b; Nielsen et al. 1999: 86; Mincarone et al 2007: 55, fig. 3R.

Porogadus subarmatus Vaillant, 1888: 265 , pl. 24 figs. 3–3c; Nybelin 1957: 288, textfig. 20, pl. 6 fig. 7; Nielsen et al. 1999: 86.

Celema subarmata: Goode & Bean 1896: 330 .

Porogadus (Dermatorus) subarmatus: Nolf 1980: 91 , pl. 11 fig. 9 (otolith).

Material examined (39 specimens): Specimens labeled as P. catena : Lectotype and paralectotype USNM 37341 , 214 and 220 mm SL, 28°00’N 87°70’W, 2683 m , Albatross Expedition 1883–1900, Sta. D 2379, large beam trawl, 2 March 1885; NMP 1873 (4 specimens), 152–170 mm SL , NMP 1874 , 130 + mm SL , NMP 1871, 133 mm SL, NMP 1878 (4 specimens), 138–170 mm SL, Portiguar , Brazil, 2000m ; USNM 405732 , 140 + mm SL, 28°23’N 88°21’W, 1829 m , R / V Oregon, Cruise 68, Sta. 2820, 15 Jul 1960 ; ZMMGU 16653 (4 of 9 specimens), 152–170 mm SL , R / V Acad. Kurchatov, Cruse 1, station 2,14°45’N 18°21’W, 2880 m , 08 January 1967. Specimens labeled as P. subarmatus : Holotype MNHN 86-530 , off Cape Verde Islands , 3200 m , R / V Talisman, 1883 ; paratype BMNH 1939.2 .20.1, off Cape Verde Islands 3200 m ; BMNH 2013.8.1.38-43, 103– 193 mm SL, 20°52’N 18°17’W ( Cape Verde Plateau ), 2010–2180 m , R. R. S. Discovery Cruise, collected by the Institute of Oceanographic Sciences , 06 July 1987 ; MNHN 2004-1330, 136 mm SL, 05°46’S 09°42’E, 3113–3159 m , R / V Atalante, Biozaire 3 Expedition, Sta. cp22, 03 January 2004 ; MNHN 2004-1333 (2 specimens) 140–174 mm SL, 05°55’S 09°39’E, 3230 m , R / V Atalante, Biozaire 3 Expedition, Sta. cp24, 04 January 2004 ; MNHN 2004-1348, 204 mm SL, 05°48’S 09°42’E, 3142–3163 m , R / V Atalante, Biozaire 3 Expedition, Sta. cp18, 30 December 2003 ; MNHN 2004-1349 (2 specimens), 188 mm SL, 05°48’S 09°42’E, 3156–3172 m , R / V Atalante, Biozaire 3 Expedition, Sta. cp17, 30 December 2003 ; MNHN 2004-1350, 162 mm SL, 05°47’S 09°42’E, 3113–3159 m , R / V Atalante, Biozaire 3 Expedition, Sta. cp20, 02 January 2004 ; MNHN 2004-1352, 165 mm SL, 05°49’S 09°42’S, 3172–3193 m , R / V Atalante, Biozaire 3 Expedition, Sta. cp16, 28 December 2003 ; ZMUC P 771459, 180 mm SL, 05°48’S 09°43’E, 3156 m ; ZMUC P2397207-208 , (2 specimens), 176–191 mm SL, Galathea 2 expedition, Sta. 52, 01°49’N 07°51’E, 2620 m , 30 November 1950; ZMUC P2397209-210 , (2 specimens), 137 and 195+ mm SL, Galathea 2 expedition, Sta. 65, off Gabon, 02°17’S 08°10’E, 2840 m , 4 December 1950; ZMUC P 2397211, 183 mm SL, collected by Mr. Frank, off Rabat , Morocco, 16 September 1897, 2000 m .

Diagnosis. Precaudal vertebrae 16–17; long gill rakers on first gill arch 15–18; pectoral-fin rays 15–18; HL:HD 1.49–1.73; few and mostly weak head spines, present on ethmoidal, supraorbital, sphenotic, supratemporal, outer posttemporal, inner preopercular rim; absent on lacrimal, prefrontal, interorbital, 5th infraorbital, inner posttemporal, outer preopercular rim; opercular spine weak, flat; opercular flap small; lower lateral line pores until beginning of anal fin 15–17; vomer with narrow dentition patch with 1–2 rows of teeth; palatines with moderately broad dentition patch with 3–4 rows of teeth; otolith with single colliculum; OL:OH = 1.0–1.2; OL:TCL = 1.8–2.2.

Description (holotype values refer to P. catena ). Meristics: precaudal vertebrae 17 (16–17), 1 (0–2) last vertebrae without ribs; pectoral-fin rays 16 (15–18); D/V = 6 (5–7); D/A = 25 (21–26); V/A = 18 (17–18); long gill rakers on lower gill arch 16 (15–18). Gill rakers in a non-type (ZMUC P771459) on lower first gill arch with nine short rakers, followed by a series of 17 long rakers. The lower eight of those intercept by narrow plate shaped rakers, placed toward the inner margin. Upper gill raker with a series of two plate-like rakers followed by four semi-long and plate-like rakers intercepted, followed by two very short rakers.

Morphometrics: in % of SL: HL 14.5–16.4; maximal HD 8.5–10.7; HD through center of eye 5.8–7.5; bony interorbital width 2.8–3.5; snout length 4.0–5.3; upper jaw length 8.7–10.4; predorsal 15.8–19.6; preanal 28.0–33.3; prepelvic 11.7–13.4; prepectoral 15.0–17.6; pectoral length 7.5–9.5. Relations: HL:HD = 1.59 (1.49–1.73); HL to snout length 2.77–3.28; preanal to predorsal 1.64–1.88; predorsal to prepectoral 1.0–1.13.

Slender fish with long tapering tail and relatively short head and snout. Maximal size of fishes investigated 220 mm SL (paralectotype). Head relatively short and compressed, with mostly flat dorsal profile, and mostly weak spines as follows: ethmoidal (1 sharp), supraorbital (1 weak), sphenotic (1–2 weak), supratemporal (1–2 weak), outer posttemporal (1–2 weak), inner preopercular rim (1–3); no spines on lacrimal, prefrontal, interorbital, 5th infraorbital, inner posttemporal, outer preopercular rim. Opercle with weak, flat spine. Eye moderately 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; extensive cavernous system on head top in front of occiput and nape, sometimes open (pores or damaged thin skin?). Head squamation only discernable on opercle and cheeks on few specimens. Opercle with two or three moderately sized neuromast behind preopercular edge; opercular flap small. Lateral line rows rarely well visible and therefore number of pores countable only in rare instances. Lower lateral line row with 15–17 pores until beginning of anal.

Dentition. All teeth small and cone-shaped. Vomer V-shaped usually with 3 rows of teeth anteriorly and one row posteriorly; palatines with a moderately broad dentition patch with 3–5 rows of teeth; premaxilla tooth patches narrow and not fused anteriorly; 5–8 rows of teeth anteriorly and 1–3 posteriorly; dentary tooth patches not fused anteriorly; ca. 4–7 rows anteriorly and 1–4 rows posteriorly. Median basibranchial tooth patch long and narrow

Otolith morphology (n = 12). Size 2.0 mm in length; OL:OH = 1.02–1.21; OH:OT = 2.0–2.7. Moderately thick, small, compressed, roundish otolith. All rims rounded and smooth. Inner face flat, with short, deepened, centrally positioned sulcus; OL:TCL = 1.83–2.24. Sulcus with undivided, uniform, sometimes deepened, oval colliculum. Dorsal field with indistinct depression; ventral field smooth. Outer face smooth, with prominent central umbo.

Coloration. Live coloration not known. Color of preserved specimens light to medium brown; entire head darker, opercle distinctly darker, almost black.

Discussion. Porogadus catena belongs to the Porogadus catena group further containing P. promelas and as a group is characterized by weak head spines and a compressed, relatively short head. Porogadus catena was originally described from the western Atlantic and has been considered as senior synonym of P. breviceps and P. promelas from the eastern Pacific by Carter & Sulak (1984). However, we found certain consistent differences between Atlantic and East-Pacific specimens with the Atlantic ones ( P. catena ) showing weak supratemporal and inner preopercular spines (vs absent), scales on cheeks and opercle equally large (vs scales on cheeks larger than on opercle), narrower palatines (with 3–4 rows of teeth vs 4–9 rows), and a distinctly more compressed otolith (OL: OH = 1.02–1.21 vs 1.25–1.51), indicating that two vicariant species exist in the respective seas. We therefore regard both P. catena and P. promelas (the latter with P. breviceps as junior synonym) as valid. In contrast we were unable to find consistent differences between the specimens from the West-Atlantic commonly placed in P. catena and from the East-Atlantic usually identified as P. subarmatus and therefore place the latter as junior synonym of the former.

Distribution. Porogadus catena is relatively common on both sides of the tropical to subtropical Atlantic from about 30°N to 12°S in the West-Atlantic and about 35°N to 10°S in the East-Atlantic. It has been caught at depths mostly between 1800 and 3200 m and one specimen between 4500 and 4600 m from the East-Atlantic where it appears to be residing somewhat deeper than the West-Atlantic. Also, it appears to be staying relatively close to the continental slope and has not been caught further away from the shelf break than 700 km.

Figures

FIGURE 34. Porogadus catena (Goode & Bean, 1885); 34A,C, NPM 1878, 170 mm SL, off Portiguar, Brazil, 2000 m; 34B, ZMUC P771459, 180 mm SL, 05°48'S, 09°43'E, 3156 m; 34D, NPM 1878, 145 mm SL, off Portiguar, Brazil, 2000 m.

FIGURE 35. Porogadus catena (Goode & Bean, 1885); 35A, USNM 37341, paralectotype, 220 mm SL, 28°00’N 87°70’W, 2683 m, head drawing; 35B, MNHN 86-530, holotype of Porogadus subarmatus, Cape Verde Islands, 3200 m, head drawing; 35C–D, ZMUC P771459, 180 mm SL, 05°48’S, 09°43’E, 3156 m, head drawings; 35E–F, NPM 1878, 170 mm SL, off Portiguar, Brazil, 2000 m, head drawings; 35G–H, NPM 1873-0021994, 150+ mm SL off Portiguar, Brazil; otolith (G inner face, H ventral view); 35I, NPM 1878, 170 mm SL, off Portiguar, Brazil, 2000 m, otolith (inner face); 35J, NPM 1874, NPM 1878, 170 mm SL, 130+ mm SL, off Portiguar, Brazil, 2000 m, otolith (inner face); 35K, NPM 1873-0021919, 142 mm SL, off Portiguar, Brazil; otolith (inner face); 35L,P,Q, MNHN 2004-1349, (2 specimens), 188 mm SL, 05°48’S, 09°43’E, 3156 m, otoliths (L,P inner faces, Q ventral view); 35M–O, BMNH 1939.2.20.1, Cape Verde Islands, 3200 m, otolith (M inner face, N dorsal view, O anterior view); 35R–S, MNHN 2004-1352, 165 mm SL, 05°49’S, 09°42’E, 3172 –3193 m, otolith (R inner face, S ventral view).

FIGURE 47. Geographic distribution of the species of the Porogadus catena group.

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