Leptoderma ospesca, Angulo, Arturo, Baldwin, Carole C. & Robertson, D. Ross, 2016

Angulo, Arturo, Baldwin, Carole C. & Robertson, D. Ross, 2016, A new species of Leptoderma Vaillant, 1886 (Osmeriformes: Alepocephalidae) from the Pacific coast of Central America, Zootaxa 4066 (4), pp. 493-500 : 494-498

Leptoderma ospesca n. sp.

(Fig. 1)

Holotype. USNM 421478, 197 mm SL; El Salvador, Central America, Eastern Pacific Ocean, research vessel B/ O Miguel Oliver station MOP11–94, trawl on soft-bottom from 12º 53' 15.72" N, 90º 9' 30.6" W to 12º 53' 22.9194" N, 90º 7' 56.28" W, at 1368–1406 m; December 11, 2010; D. Ross Robertson.

Diagnosis. Leptoderma ospesca differs from L. affinis , L. macrops and L. retropinna by having a distinct gap between the posterior ends of the dorsal and anal fins and the origins of the upper and lower procurrent caudal-fin rays. From L. lubricum , the new species differs by lacking dermal papillae along the lateral line, by having pectoral fins low on body (vs. high) with 6 fin rays (vs. 7–8), and by having fewer caudal-fin rays (16, vs. 17–18). From L. macrophthalmum , the new species differs by having a longer pre-dorsal length (54.9% SL, vs. 49.3%), fewer pectoral-fin rays (6, vs. 8), fewer pelvic-fin rays (5, vs. 8) and longer dorsal- and anal-fin rays (vs. shorter). Leptoderma ospesca also differs from all congeneric species by having fewer pre-ural vertebrae (60, vs. 64–84).

Description. Measurements and counts of L. ospesca and comparative data are presented in Table 1 . Body naked, relatively long, subcylindrical anteriorly and laterally compressed posteriorly, with greatest body depth at a distance of 24.3% SL from snout; dermal papillae absent from head, along lateral line and dorsum; lateral line pores inconspicuous.

Head length (HL) almost twice greatest body depth. Nostrils with large longitudinal openings, partly covered by a dermal flap, located nearer to eye than to snout tip. Mandibular pores 4, supraorbital pores 3, suborbital pores 4 and preopercular pores 3. Snout blunt, relatively large, its length 30.3% of HL, shorter than eye. Mouth subterminal. Teeth minute to small, conical and well separated, present in one row on premaxilla and one on dentary; no teeth on palate. Supramaxilla slender, curved. Upper jaw relatively short, barely reaching front border of eye, its length 33.0% of HL. Lower jaw ending under orbit. Eyes large, 37.5% of HL, directed outward and slightly upward, with upper margin protruding above dorsal profile of head. Interorbital space relatively large, 17.2% of HL. Postorbital length 32.2% of HL. Maximal head width (behind eyes) 34.5% of HL. Pseudobranchiae small. Pectoral fins inserted relatively low on body, uppermost fin ray at level of dorsal corner of gill opening, slightly below midbody. Pelvic fins abdominal, length 71.1% of pectoral-fin length. Pelvic-fin base located just in front of anus. Genital papilla short, located between anus and anal-fin origin. Anal-fin origin well in advance of dorsal-fin origin; length of dorsal-fin base 60.4% of length of anal-fin base. Dorsal- and anal-fin rays long, longer rays greater than half body depth at level of anus. Both dorsal and anal fins separated from caudal fin. Procurrent caudal-fin rays numerous, extending far forward on caudal peduncle. Dorsal and anal procurrent caudal sections about equal in length. Caudal fin small, forked, with 8 principal rays in each lobe.

Color in life. Head, eye, and anterior part of body bluish black, turning gradually lighter brownish towards posterior part of body (Fig. 1A).

TABLE. 1 . Mοrphοmetric and meristic characters οf six Leptoderma species. Measurements and cοunts nοt attainable (i.e. structure absent οr incοnspicuοus) οr unavailable are represented an en‾dash (‾). When the number οf examined specimens used tο determine the respective measurement οr cοunt differs frοm the tοtal, the number οf examined specimens is indicated in parenthesis.

Character L. affinis L. lubricum L. macrops L. macrophthalmum L. ospesca L.retropinna

n=1 2, * n=21 3, * n= 52 4 n=1 5, * n=1 1, * n=27 6 (mm) 222.5 29.7‾210 141‾210 151 197 28.4‾152

Morphometric characters as % SL

‾dοrsal length ‾ 55.1‾61.1 47.3‾56.4 (49) 49.3 59.4 55.0‾58.7 (6) ‾anal length ‾ 41.0‾46.5 (20) 35.5‾44.2 (49) 45.7 46.4 40.9‾45.6 (6) ‾pelvic length ‾ 36.8‾41.8 (20) 31.0‾43.8 (49) 39.5 38.0 34.4‾38.7 (6)

Dοrsal-fin base, length ‾ 25.3‾28.9 (5) 44.7‾58.1 (14) 31.1 25.5 41.0‾47.6 (6)

Dοrsal prοcurrent caudal-fin sectiοn, length ‾ 15.0‾16.6 (5) 3.2-3.6 (3) 15.5 14.1 4.5-4.7 (2)

Anal-fin base, length ‾ 36.6‾41.0 (5) 58.6‾73.6 (14) 40.7 42.2 50.0‾59.0 (6)

ventral prοcurrent caudal-fin sectiοn, length ‾ 14.0‾16.9 (5) 3.4-4.2 (3) 15.1 14.0 4.1-5.3 (3)

Pectοral-fin length ‾ 5.0‾11.4 (5) 6.0‾8.4 (14) 7.3 7.0 4.9‾5.8 (5)

Pelvic-fin length ‾ 1.8‾6.9 (5) 3.9‾5.8 (14) 4.8 5.0 4.0‾4.9 (5)

Greatest bοdy depth c.11.1 11.1‾14.7 (5) 9.8‾12.3 (14) 12.8 13.4 7.8‾9.2 (6)

Caudal-peduncle depth ‾ 2.0‾2.8 (5) 0.9‾1.5 (14) 2.1 1.8 1.1‾1.3 (6)

Maximal head width (behind eyes) ‾ 8.6‾14.9 (20) 7.8‾9.2 (14) 11.3 8.4 6.6‾8.6 (6) length c.22.2 22.8‾25.7 (5) 16.7‾24.4 (49) 23.2 24.3 18.7‾21.7 (6)

Snοut length ‾ 7.0‾8.3 (5) 3.8‾7.0 (49) 7 7.4 5.3‾7.0 (6)

Hοrizοntal οrbital diameter ‾ 7.5‾9.0 (5) 5.7‾9.4 (49) 9.3 9.1 3.3‾7.2 (6)

Pοstοrbital length ‾ ‾ ‾ 6.9 7.8 ‾

Interοrbital distance ‾ 3.1‾5.1 (5) 1.6‾5.6 (49) 3.4 4.2 3.3‾5.7 (6)

Upper-ϳaw length ‾ 5.6‾8.9 (5) 4.6‾7.3 (49) 7.9 8.0 5.3‾7.3 (6)

……continued on the next page vertebrae, hemal (excl. urοstyle) ‾ 49‾55 (4) ‾ 51 ‾ ‾

vertebrae, tοtal (excl. urοstyle) ‾ 64‾77 (20) 79‾84 (35) 66 60 77 (1)

Dermal papillae οn lateral line:es:es (5):es;ο;ο;ο (5)

US;M 421478, n<1. 2 Data frοm Alcοck (1899). 3 Data frοm Abe et al. (1965), n<1=>akami? @ukui (2010), n<15= and US;M 135621, n<1. 4 Data frοm Markle (1976), n<35= US;M 215604, n<6= US;M 215606, n<3= US;M 290727, n<1= US;M 407283, n<1= US;M 407399, n<1= US;M 407400, n<1= US;M 407401, n<1= and US;M 435839 (ABCGA; 4562), n<3. 5 Data frοm 9yrkϳedal et al. (2011), n<1. 6 Data frοm>akami? @ukui (2010), n<21= US;M 150804, n<2= and US;M 150806, n<3. D Data frοm, οr including, the Hοlοtype.

FIGURE. 1. Leptoderma ospesca n. sp., holotype (USNM 421478), A: preserved entire specimen; B: newly caught entire specimen, arrows indicate position of gaps between dorsal and anal fin rays and upper and lower procurrent caudal rays, respectively; C close-up of head region of newly caught specimen. Note: The structure near the lateral midline above the anus that is visible in Fig. 1A (but not obvious in Figs. 1B or C), is a piece of loose skin adhered to the body.

Color in alcohol. Head and anterior part of body black, turning gradually lighter grayish towards posterior part of body (Fig. 1B).

Distribution. Known only from the holotype collected off El Salvador, between 12º 53' 15.72" N, 90º 9' 30.6" W and 12º 53' 22.9194" N, 90º 7' 56.28" W, Central America, eastern Pacific Ocean, at a depth of 1368–1406 m. Etymology. The specific name “ ospesca ” recognizes the contribution of OSPESCA (Organización del Sector Pesquero y Acúicola de Centroamerica) to the discovery of deepwater marine fishes in Central America by sponsoring research cruises of the Spanish research vessel B/ O Miguel Oliver on both the Pacific (2010) and Atlantic (2011) coasts of Central America.

Suggested common names. Eastern eel-slickhead; Cabezalisa oriental.

Tables

TABLE 1. (Cοntinued)

Character	L. affinis n=1 2, *	L. lubricum n=21 3, *	L. macrops n=52 4	L. macrophthalmum L. ospesca n=1 5, * n=1 1, *	L.retropinna n=27 6
Meristic characters Dοrsal-fin rays	c.66	33‾40	57‾67 (49)	32 33	46‾56 (26)
Dοrsal prοcurrent caudal-fin rays Anal-fin rays ventral prοcurrent caudal-fin rays	‾ c.85 ‾	21‾29 45‾56 19‾26	‾ 74‾85 (49) ‾	21 25 47 48 20 22	7‾9 (21) 65‾72 (26) 6‾8 (21)
Pectοral-fin rays Pelvic-fin rays Principal caudal-fin rays Gill rakers οn first arch 8ateral-line pοres 9ranchiοstegals vertebrae, visceral	‾ 5 ‾ ‾ ‾ ‾ ‾	7‾8 4‾6 17‾19 15‾18 58‾66 (5) 5 15‾17 (4)	8‾9 (14) 5‾6 (14) 14‾17 (14) 11‾15 (49) ‾ 4‾6 (49) ‾	8 6 8 5 16 16 19 16 c.48 ‾ 5 ‾ 15 ‾	6‾8 5‾8 16‾18 (26) 10‾18 ‾ 7 (6) ‾