Comprehensive Description

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Pseudoscopelus lavenbergi , new species

(Figs. 4, 5 and 6; Tables 2 and 3)

Holotype . SIO 71-358 (73.0), eastern Pacific, off Ecuador , 01°21.0’N , 086°36.0’W , 21-III-1967 , R/V Alaminos.

Paratypes . Eastern Pacific: CAS 61407, 1 (63.0), Ecuador , Humboldt Current area, 02°26'S , 88°46'W , 0- 300 m, 27/ 28-V-1966 , R/V Anton Bruun ; LACM 33335-1, 1 (82.2), south of the Galapagos Islands , 400 m, 1°48’S , 90°19’W , 26-V-1966 ; LACM 33340-1, 1 (45.3), ca. 180 miles SE of the Galapagos Islands , 2°59’S , 88°11’W , 2300-3000 m, Te Vega Expedition, 25-IX-1968 ; LACM 30074-8, 1 (102.7), Baja California , 28°48’N , 114°28.48’W , 11-IV-1968 , R/V Velero IV ; LACM 30379-2, 1 (91.4), Baja California , 49 miles from Punta Abreojos, 26°0.66’N , 114°10’W , 24-VI-1968 , R/V Velero IV ; LACM 30530-1, 1 (166.6), California , 32°19.75’N , 117°49.11’W , 27-I-1968 , R/V Velero IV ; LACM 30573-1, 2 (86.3-97.6), Baja California , from Punta Abreojos, 22°30’N , 110°00’W [inferred by authors], 1324-1624 m, 23-VI-1968 , R/V Velero IV ; LACM 31793-1, 1 (143.9), California , San Clemente Island, 10.5 miles from Pyramid Head, 32°40’N , 118°20’W [inferred by authors], 29-VII-1969 , R/V Velero IV ; LACM 33336-1, 1 (76.5), Baja California , about 100 miles west of Cabo San Lazaro, 24°55’N , 114°12’W , 29- 30-III-1962 ; SIO 56-109-60A, 1 (30.2), from stomach of Alepisaurus ZBK taken by longline, 01°57.5’N , 110°39.0’W , M/V N.B. Scofield ; SIO 75-316, 1 (73.0), 06°03.1’N , 117°46.0’W , 30-I-1973 , R/V David Starr Jordan ; SIO 92-9, 1 (54.9), 08°05.0’N , 095°02.0’W , 21-IX-1967 , R/ V Rockaway ; SIO 93-22, 1 (67.7), off Mexico , 19°2.5’N , 105°40.5’W , 14-IX-1967 , R/V Thomas Washington ; SIO 95-83, 1 (70.4), 08°36’N , 111°32’W , 5-I-1968 , R/V David Starr Jordan ; SIO 97-203, 1 (81.6), 20°00’N , 129°00’W , 1000 meters of wire, 27-V-1973 , R/V David Starr Jordan . Central Pacific , south of Hawaii: USNM 289000, 1 (47.4), 10°58’N , 150°00’W , 950 m, 14-I-1978 , R/V Kana Keori ; USNM 289002, 1 (44.5), 10°10’N , 150°00’W , 710 m, 30-V-1979 , R/V Gyre ; UW 116439 (former SIO 60-243), 1 (44.7), 10°22.3’N , 147°18.8’W , 0-2100 m, 8- 9-VII-1960 , Tethys Expedition .

Non-type specimens. Eastern Pacific: LACM 56617-1, 1 (84.8), off Chile , 23°52’S , 71°08’W , 0-200 m, 23-IX-1968 , R/V Akademik Kurchatov ; LACM 56618-1, 1 (173.6), off Ecuador , 0°0’ , 85°00’W , 0-1500 m, 29- VII-1968 , R/V Akademik Kurchatov ; LACM 30205-29, 1 (133.1), California , San Clemente Island, 32°33.45’N , 118°10.08’W , 1812-1464m, 26-VII-1968 , R/V Velero IV ; LACM 33334-1, 1 (39.9), probably off Southern California or Baja California , 13-V-1966 ; LACM 33337-1, 1 (60.4), Gulf of California ; LACM 33339-1, 1 (181.8), California , 0.3 miles 183oT from West End Light, Santa Catalina Island, 27-VIII-1970 , R/ V Velero ; SIO 95-131, 1 (36.4), 3°11.5’N , 119°21.0’W , 26-X-1967 , R/V David Starr Jordan ; SIO 69-330, 1 (34.2), 14°46.0’S , 93°32.5’W , 18-III-1969 ; SIO 63-165, 1 (159.9), 28°53.0’N , 118º08.4’W , 21-IV-1963 , 0-750 m, R/V Horizon . Central Pacific, Hawaii : LACM 30042-10, 1 (ca. 80.0) Leward Oahu, 21°20.5’N , 158°20.5’W , 600-650 m, 9-X-1970 , R/V El Pescadero II .

Diagnosis. Pseudoscopelus lavenbergi can be distinguished from its congeners by three unique characters: trf in broad band of three or more rows (vs. trf absent on P. scutatus ZBK and P. bothrorrhinos ; in single row with widely spaced organs on P. altipinnis ZBK ; and in single row with closely spaced organs on remaining species); ptvf short, not reaching anus, and extending anteriorly only halfway to pelvic-fin origin (vs. ptvf elongate, extending close to anus, and extending anteriorly to very close to pelvic-fin origin); mxf completely absent and apf present (vs. both mxf and apf absent on P. scutatus ZBK and P. bothrorrhinos ; both apf and mxf present on remaining species).

Description: Meristic data summarized in Table 2, and morphometric data in Table 3. Moderate-sized species of Pseudoscopelus ZBK , largest specimen 181.0 mm SL. Body elongate, fusiform, not greatly compressed anteriorly, but progressively more compressed in caudal region. Greatest body depth at origin of first dorsal fin. Scales absent, except for lateral line.

Anterior profile of head round in lateral view. Tip of snout protruding, with abrupt curve dorsally at level of anterior naris. Mouth terminal and large, reaching edge of preopercle. Orbit circular. Nares distinctly separated, anterior naris circular, close to third supraorbital pore; posterior naris C-shaped, close to anterodorsal edge of eye.

Teeth present on premaxilla, dentary, and palatine. Premaxillary and dentary dentition of P. lavenbergi illustrated in Fig. 5. Premaxilla wide; premaxillary teeth arranged in three series: lateral, middle and mesial. Lateral series at edge of premaxilla, first tooth curved orally, type 1; remaining teeth at lateral edge curved caudally, type 4. Middle series in irregular rows of one to two straight teeth, needle-like, type 4, size increasing from lateral to mesial. Mesial series in transverse rows of one to four teeth, needle-like, type 4, size increasing from lateral to mesial. Dentary teeth in two rows: lateral and mesial. Lateral series at edge of dentary conical, type 4; mesial row in series of one to three teeth, needle-like, type 4. Palatine teeth conical, type 1, arranged in single row.

Gill arches four; pseudobranch present. Epibranchial of first arch attached to opercle to midline; ceratobranchial, hypobranchial and basibranchial of first arch free. Epibranchials of second, third and fourth arches connected anteriorly to each other and pharyngobranchials; ceratobranchial of second arch free. Hypobranchial and basibranchial of second, third and four arches connected medially. Ceratobranchial of third arch connected anteriorly to fourth arch; ceratobranchial of fourth arch connected medially to body wall at anterior half. Gill rakers short, conical, similar to type 1 tooth; present on first basibranchial, first and second gill arches, and pharyngeals; absent on basihyal, other basibranchials, third and fourth gill arches. Rakers of first basibranchial arranged in V-shaped row.

Pectoral fin elongate, reaching origin of second dorsal and anal fins; pelvic-fin origin slightly posterior to pectoral-fin base; dorsal fins two, first dorsal-fin origin slightly posterior to pelvic-fin insertion, second dorsal-fin origin at level of anal-fin origin. Sensorial system of head as in Fig. 2; pore counts listed in Table 2. Lateral line complete, with pores opening between scales; last scale of lateral line separate, on lower lobe of caudal fin, with two pores (included in lateral-line pore count). Total vertebrae 37-39 (mode=38, n=5), precaudal17-18 (mode=17, n=5).

Color. No freshly collected specimens known, most specimens bleached; two well preserved specimens completely dark brown, including fins. Oral and branchial cavities dark, including gill arches; gill filaments not pigmented.

Luminescent organs. Luminescent organs present as discrete photophores on head and body; pattern of P. lavenbergi illustrated in Fig. 6. Photophores on head: dnf, info 1-2, mxf, opf, pof absent; vnf as small triangular patch of few organs, slightly posterior to first supraorbital pore; apf triangular, short, restricted to angle between premaxilla and preopercle; amf medial on dentary, elongate, beginning halfway between second and third mandibular pores, extending to midpoint between third and fourth pores; pmf lateral on dentary, elongate, originating slightly posterior to fourth mandibular pore, extending halfway between fifth and sixth pores, in one to two irregular rows. Photophores on body: rtf spf, svf and scf absent; pf in single row along ventralmost pectoral-fin ray; paf in triangular patch at pectoral-fin axil; vf short, in single row, restricted to first third of mesial pelvic-fin ray; vaf extending over base of pelvic rays 4-5; if elongate, in two to four rows of photophores; prvf short, 1/3 of if, in one to four rows; ptvf short, from halfway between anus and pelvic fin, to close to anus, in one to three rows; trf in broad band of three or four rows; saf reaching anus, but not extending further anteriorly, in single row except for anterior part, posterior ends not connected; prcf in two rows anteriorly and three to four rows posteriorly, short, extending from posterior part of peduncle and extending over anterior lower procurrent caudal-fin rays.

Distribution. Pseudoscopelus lavenbergi is known from the eastern Pacific, from California to Chile, 32° N to 23° S; extending west to near the Hawaiian Islands, 158° W (Fig. 10).

Etymology. The species is named for Robert J. Lavenberg, in recognition of his contributions to our knowledge of the genus Pseudoscopelus ZBK .

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