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Etmopterus joungi n. sp., a new species of lanternshark (Squaliformes: Etmopteridae) from Taiwan.

INTRODUCTION

Lanternsharks (Squaliformes: Etmopteridae: Etmopterus) are the most species-rich group of squaloid sharks with more than thirty small, darkly colored species recognized within the genus (Compagno et al. 2005; Schaaf-DaSilva & Ebert 2006). Members of this deepwater genus are found world-wide in temperate and tropical waters (Last et al. 2002) and often are captured by benthopelagic trawls at depths greater than 200 meters (Joung & Chen 1992; Compagno et al. 2005). There are multiple lineages within the the genus (Last et al. 2002; Straube et al. 2010). The genus is readily separated into three groups based on the shape and distribution patterns of dermal denticles (Springer and Burgess 1985; Yano 1988). Two of these appear to the natural species groups and the third, containing species with slender, needle-shaped denticles in random and dense array, is likely Paraphyletic (see Straube et al. 2010). The "lucifergroup" comprises those species that possess thorn-like dermal denticles arranged in linear rows along the body (Bigelow and Schroeder 1957; Garrick 1957, 1960; Yamakawa et al. 1986; Yano 1988; Schaaf-Da Silva & Ebert 2006). There are eight currently recognized species and additional species await description (GHB and Rui Coelho, in prep.). Springer and Burgess (1985) and Shirai and Tachikawa (1993) have defined another complex with randomly distributed truncate, crater-shaped dermal denticles, the "pusillus-group." Members of this group, Etmopterus pusillus (Lowe, 1839) and Etmopterus bigelowi Shirai and Tachikawa, 1993, also possess a lateral line that ends in an open groove, suprapelvic flank markings lacking a posterior branch, and a relatively cylindrical body (Shirai & Tachikawa 1993). A nominal third species of concave denticle-bearing Etmopterus described from the Sagami Sea, Japan, E. frontimaculatus (Pietschmann, 1907), was placed in the synonymy of E. pusillus by Bigelow et al. (1955) and Shirai & Tachikawa (1993).

Members of the "pusillus-group" are wide-ranging, occurring mostly in deep, benthic and semipelagic habitats (Shirai & Tachikawa 1993; Compagno et al. 2005; Last & Stevens 2009). Etmopterus pusillus, originally described from Madeira based on four syntypes, two of which have subsequently been lost, is widespread in the Atlantic, Pacific and Indian oceans (Shirai & Tachikawa 1993). Submersible observations of E. pusillus made in the south-western Indian Ocean found Etmopterus pusillus between 985-1812 m depth with the highest abundance occurring from 985-1350 m (Lindsay et al. 2000). Shirai and Tachikawa (1993) described Etmopterus bigelowi, the other member of this group, from off Angola and documented a broad geographic range including the Gulf of Mexico, Caribbean Sea, western Indian Ocean, Western Australia and the western and central North Pacific. Critical comparison of pusillus-like Etmopterus (e.g. those with flat, concave dermal denticles) from the eastern Atlantic, type localities of E. bigelowi and E. pusillus, to those from other regions, particularly those from the western North Pacific, has been inadequate. A comparative study of eastern and western Atlantic members of this group is forthcoming (GHB & Coelho, in prep.).

Etmopterus bigelowi and E. pusillus have been reported from throughout the western North Pacific including Japan, the Ryukyu Islands, and the East China Sea (Compagno et al. 2005) and E. pusillus also occurs in Taiwanese waters (Last & Stevens 2009). During a field survey of fish markets in Taiwan, two of us (DAE and GHB) collected several Etmopterus that showed the charac-teristics of the "pusillus group" but appeared to be different from E. pusillus and E. bigelowi. Upon closer examination it was determined that they represented a new species of pusillus-like Etmopterus. Herein we describe this new etmopterid.

MATERIALS AND METHODS

Morphometric measurements were made following Last et al. (2002) and Schaaf-Da Silva & Ebert (2006), except for the dorsal fin lengths that were defined as the length from the anterior point of emergence of the corresponding spine to the tip of the dorsal fin (Shirai & Tachikawa 1993). All measurements are reported in millimeters (mm) and presented in proportion to the total length (TL). Meristic measurements include vertebral counts, spiral valve turns and upper and lower tooth counts. We examined comparative material from the collections of the British Museum of Natural History (BMNH), Bernice P. Bishop Museum (BPBM), California Academy of Sciences (CAS), Commonwealth Scientific and Industrial Research Organization (CSIRO), Florida Museum of Natural History (UF), Hokkaido University Museum (HUMZ), and South African Museum (SAM). Institutional acronyms follow Leviton et al. (1985).

RESULTS

Etmopterus joungi n. sp.

Shortfin Smooth Lanternshark

(Fig. 1, Table I)

[FIGURE 1 OMITTED]
Table I. Morphometries and meristics of the holotype and paratypes
of Etmopterus joungl n. sp., expressed as % TL.

                    CAS-227957  UF-159309  UF-159380  UF-159703
                      Female      Male       Female       Male
                     Holotype   Paratype   Paratype   Paratype

Total length            435 mm     406 mm     344 mm     319 mm

Pre-first dorsal          36.3       33.7       36.6       34.5
length

Pre-second dorsal         66.0       63.5       64.0       61.4
length

Head length               15.9       15.3       16.0       15.4

Pre-branchial             17.5       17.0       18.9       16.9
length

Pre-spiracle              10.8       11.1       12.5       11.0
length

Pre-orbital                3.9        4.7        5.2        4.7
length

Pre-oral length            8.0        8.4        8.7        8.2

Eye length                 4.1        3.9        5.2        4.7

Eye height                 2.3        2.2        2.9        2.5

Spiracle length            1.4        1.5        1.5        1.3

Eye spiracle               2.5        2.5        2.9        3.1
distance

First gill slit            1.1        2.2        1.5        1.3
height

Fifth gill slit            0.9        1.2        1.2        1.3
height

Mouth length               1.6        1.2        1.7        1.9

Mouth width                6.4        6.9        7.6        7.5

Upper labial               1.6        2.0        1.7        1.3
furrow length

Lower labial               0.7        1.0        0.9        0.9
furrow length

Nostril width              2.3        2.2        2.3        1.9

Interorbital               6.2        6.7        8.1        6.6
distance

Internarial                4.4        2.2        3.2        3.4
distance

Head height                8.3        8.6        6.4        7.8

Head width                 8.7        8.1       10.2        8.8

Pre-pectoral              22.1       22.2       23.8       20.4
length

Pre-pelvic length         54.5       52.0       54.1       53.6

Snout-vent                59.8       57.9       59.6       59.2
distance

Pectoral-pelvic           29.0       26.4       25.3       27.3
distance

Interdorsal               25.5       25.9       23.3       23.5
distance

Dorsal-caudal             11.0        9.9        7.6       11.0
distance

Pectoral fin               8.3        5.9        5.5        5.6
anterior margin
length

Pectoral fin inner         4.6        5.2        6.1        5.0
margin length

Pectoral fin               3.9        5.4        4.4        4.1
posterior margin
length

Pectoral fin base          4.8        4.2        3.8        4.4
length

First dorsal fin           8.0        8.1        8.1        8.5
maximum length

First dorsal fin           4.8        4.9        4.4        4.4
base length

First dorsal fin           3.4        3.7        4.4        4.4
inner margin
length

First dorsal fin           2.3        1.7        2.3        1.9
height

First dorsal fin           1.8        2.5        2.9        3.4
posterior margin

First dorsal spine      Broken        4.4        3.5        3.8
length

Second dorsal fin         11.0       12.3       12.2       12.2
maximum length

Second dorsal fin          5.7        6.7        6.4        6.0
base length

Second dorsal fin          5.3        5.7        5.5        5.6
inner margin
length

Second dorsal fin          3.4        2.7        3.2        3.8
height

Second dorsal              6.7        8.4        7.6        6.9
spine length

Pelvic fin length         10.1       11.6       11.0       10.3

Pelvic fin                 5.5        3.7        6.7        5.0
anterior margin
length

Pelvic fin base            7.4        7.4        5.5        9.1
length

Caudal fin dorsal         15.4       15.3       18.6       19.4
caudal margin

Caudal fin fork            5.3        4.9        5.8        3.8
width

Caudal fin                 9.7        7.4        7.8        6.6
preventral margin
length

Caudal fin                 2.8        2.5        2.9        3.4
subterminal margin
length

Caudal fin upper           6.4        5.9        9.0        6.0
postventral
margin

First dorsal fin          10.6       11.3       13.4       13.8
midpoint to
pectoral fin
insertion

First dorsal fin          16.1       15.8       12.5       14.4
midpoint to pelvic
fin origin

Pelvic fin                18.2       17.5       19.2       20.4
midpoint to first
dorsal fin
insertion

Pelvic fin                 7.6        8.6        4.4        3.8
midpoint to second
dorsal fin origin

Flank                     17.9       10.3        5.8        6.3
photo-marking base
length

Flank                     11.0        7.6       10.8       10.7
photo-marking
anterior branch
length

Vertebrae,                  48         40         38         41
monospondylous

Vertebrae,                  17         23         24         21
diplospondylous

Vertebrae,                  24         25         22         23
dorso-caudal

Vertebrae, total            89         88         84         85

Spiral valve                11        N/A        N/A        N/A
turns

Tooth count, upper          27         25         25         30
jaw

Tooth count, lower          42         36         33         36
jaw


Holotype: CAS 227957, 456 mm TL (435 mm TL after preservation), immature female, Ta-Chi, Taiwan, ca. 24[degrees]53'N, 122[degrees]01'E, coll. David A. Ebert at a fish market, 23 May 2005.

Paratypes: UF 159309, 406 mm TL, mature male, Ta-Chi, Taiwan, ca. 24[degrees]53'N, 122[degrees]01'E, coll. George H. Burgess, David A. Ebert & William White at a fish market, 23 May 2005.; UF 159380, 344 mm TL, immature female, Ta-Chi, Taiwan, ca. 24[degrees]53'N, 122[degrees]01'E, coll. George H. Burgess, David A. Ebert, William White & Wade Smith at a fish market, 24 May 2005; UF 159703, 319 mm TL, immature male, Ta-Chi, Taiwan, ca. 24[degrees]53'N, 122[degrees]01'E, coll. William White & Wade Smith at a fish market, 26 May 2005.

Comparative Material:

Etmopterus bigelowi: Holotype, HUMZ 100176, 459 mm TL adult male, SE Atlantic off Angola, 11[degrees]37'S, 5[degrees]13'W, 21 November 1982, 526 m (digital images kindly provided by Kazuhiro Nakaya). Paratypes, CAS 56056 (N=2), 348 mm TL male and, 401 mm TL male, R/V Oregon sta. 3724, Gulf of Mexico off Mississippi River Delta, 29[degrees]04'N, 88[degrees]31'W, 440 m, 24 August 1962; CAS 48786, 325 mm TL female, R/V Oregon II cr. 45, Gulf of Mexico, 29[degrees]08'N, 88[degrees]14'W, 420 m, 8 May 1973. Non-Types, CAS 222997, 410 mm TL mature male, R/V Dr. Fridtjof Nansen sta. 3598, SE Atlantic off Angola, 16[degrees]37'S, 11[degrees]18'W, 590-608 m, 28 March 2005; CSIRO H 2350-06, 560 mm TL mature male, Indian Ocean, Western Australia, SW of Shark Bay, 26[degrees]36'S, 112[degrees]09'E, 760 m, 1989; CSIRO H 2350-08, 697 mm TL male, Indian Ocean, Western Australia, SW of Shark Bay, 26[degrees]36'S, 112[degrees]09'E, 760 m, 1989; CSIRO H 2608-01, 310 mm TL male, Indian Ocean, Western Australia, Rottnest Canyon, 31[degrees]57'S, 115[degrees]08'E, 850 m, 1991; CSIRO H 3141-20, 345 mm TL female, Indian Ocean, Western Australia near Rowley Shoals, 17[degrees]52'S, 118[degrees]16'E, 545 m, 1992; SAM 37246, 560 mm TL female, R/V Blue Bell trawl 46, 35[degrees]09.39'S, 25[degrees]17.67'E, 677 m, 12 March 2007; SAM 37247, 678 mm TL mature female, R/V Blue Bell trawl 48, 35[degrees]11.43'S, 23[degrees]11.81'E, 675 m, 12 March 2007; BPBM 30620, 267 mm TL immature male, F/V Jami Ann cr. 8805, leg 2, sta. 253, Hawaiian Islands, 10 January 1985; BPBM 40171, 395 mm TL immature female, R/V Townsend Cromwell cr. 8704, leg 2, sta. 001, north-western Hawaiian Islands SE of Hancock Seamount, 15 August 1987; BPBM 40173, 560 mm TL female, R/V Townsend Cromwell cr. 8805, leg 1, sta. 048, north-western Hawaiian Islands, 18 July 1988; BPBM 40176, 573 mm TL immature female, R/V Townsend Cromwell cr. 8805, leg 2, sta. 178, north-western Hawaiian Islands, Kanmu Seamount, 1 August 1988; BPBM 40187, 425 mm TL immature male, R/V Townsend Cromwell cr. 8805, leg 2, sta. 245, north-western Hawaiian Islands, Hancock Seamount, 19 August 1988; BPBM 40192, 445 mm TL immature male, R/V Townsend Cromwell cr. 8805, leg 2, sta. 253, north-western Hawaiian Islands, Hancock Seamount, 20 August 1988.

Etmopterus pusillus: Syntypes, BMNH 1855.11.29.27 (N=2), 194 mm TL immature male and 326 mm TL female, both Madeira. Non-Types, CAS 224990, 258 mm TL immature male, R/V Dr. Fridtfof Nansen sta. 18-2007, SE Atlantic, 24-740 m, 27 February 2007; CAS 90487, 236 mm TL female, R/V Oregon sta. 3738, Gulf of Mexico off Mississippi River Delta, 29[degrees]11'N, 88[degrees]05'W, 500-520 m, 26 August 1962; CSIRO H 1542-01, 436 mm TL mature male, Australia, Victoria, S of Warnambool, 39[degrees]04'S, 142[degrees]20'E, 1120 m, 1988; CSIRO H 1924-01, 471 mm TL female, Australia, Tasmania, W of Mawson Bay, 41[degrees]02'S, 143[degrees]47'E, 911 m, 1989; CSIRO H 1986-01, 490 mm TL mature male, Australia, Tasmania, Tasman Sea SE of Hobart, 43[degrees]50'S, 148[degrees]38'E, 1989; CSIRO H 2621-04, 403 mm TL mature male, Indian Ocean W of Bunbury, Western Australia, 33[degrees]24'S, 114[degrees]22'E, 780 m, 16 February 1991; CSIRO H 3266-01, 494 mm TL female, Australia, Tasmania, ESE of Tasman Peninsula, 43[degrees]54'S, 150[degrees]03'E, 270 m, 1992; CSIRO H 5447-01, 505 mm TL female, Indian Ocean, Ninety-East Ridge, 30[degrees]10'S, 087[degrees]S18'E, 890 m, 1999; CSIRO H 5956-01, 445 mm TL mature male, Australia, Tasman Sea, Cascade Plateau, 43[degrees]55'S, 150[degrees]25'E, 900 m, 23 April 2002; CSIRO H 6055-01, 440 mm TL mature male, Australia, Tasman Sea, West Nor-folk Ridge, 33[degrees]49'S, 166[degrees]59'E, 938 m, 2003; SAM 37566, 470 mm TL mature female, R/V Africana cr. 069, sta. A8370 069 E17, 23[degrees]19.1'S, 13[degrees]09.9'E, 407 m, 15 January 1989; SAM 37567, 423 mm TL mature male, R/V Africana cr. 069, sta. A8391 069 E29, 24[degrees]57.1'S, 13[degrees]37.7'E, 462 m, 18 January 1989; SAM 37568, 420 mm TL mature male, R/V Africana cr. 069, sta. A8392 069 E30, 25[degrees]07.2'S, 13[degrees] 38.1'E, 434 m, 18 January 1989; BPBM 40181, 406 mm TL female, R/V Townsend Cromwell cr. 8805, leg 2, sta. 178, north-western Hawaiian Islands, 1 August 1988; BPBM 40185, 227 mm TL immature female, R/V Townsend Cromwell cr. 8805, leg 2, sta. 218, north-western Hawaiian Islands, Koko Seamount, 14 August 1988; BPBM 40204-01, 402 mm TL mature male, R/V Townsend Cromwell cr. 9307, sta. 047, north-western Hawaiian Islands, SE of Hancock Seamount, 29[degrees]48'N, 179[degrees]04'E, 397-616 m, 22 October 1993; BPBM 40204-02, 400 mm TL mature male, R/V Townsend Cromwell cr. 9307, sta. 047, north-western Hawaiian Islands, SE of Hancock Seamount, 29[degrees]48'N, 179[degrees]04'E, 397-616 m, 22 October 1993; BPBM 40205, 403 mm TL mature male, R/V Townsend Cromwell cr. 9307, sta. 048, north-western Hawaiian Islands, SE of Hancock Seamount, 397-616 m, 22 October 1993.

Diagnosis: A moderate-sized species of Etmopterus with the following set of characteristics: preoral snout short, 8.0% TL (8.2-8.7); mouth broad and strongly arched; upper teeth dissimilar to lower teeth, each tooth in first functional row with single median cusp and flanked by one or two lateral cusplets on either side; lower teeth in single series, forming blade-like edge with slender, non-erect cusps; head relatively short, 15.9% TL (15.3-16.0); dermal denticles truncate, low, with block-like crowns, irregularly arranged over majority of body, extending onto dorsal fins; pectoral to pelvic fin space large, 29.0% TL (25.3-27.30); pectoral fins very narrow, posterior portion square-shaped, posterior margin acutely angular at anterior and inner margins, with no expanded corners of fins; second dorsal fin located relatively posteriorly along body, second dorsal fin spine long and strongly recurved, 0.5 (0.3-0.5) into dorsal fin height; interdorsal space about three times distance between first dorsal fin spine origin and pectoral fins; inconspicuous suprapelvic flank marking lacking posterior branch; dorsal caudal fin margin short, 15.4% TL (15.3-19.4); posterior end of lateral line becoming open groove, with ventral edge darkly colored; caudal fin short; 48 (38-41) monospondylous vertebrae, 17 (21-24) diplospondylous vertebrae, 24 (22-25) dorso-caudal vertebrae, and 89 (84-88) total vertebrae; 11 turns in spiral valve; color in life dusky grey dorsally, black to dark grey ventrally (Fig. 1).

Description: Body fusiform, relatively long, slender, narrowing posteriorly; tail slender, relatively short, narrowing posteriorly with no keels or precaudal pits, dorsal to caudal length 15.4% TL (15.3-19.4). Pre-orbital snout subtriangular in lateral view, relatively narrow; head length relatively short 15.9% TL (15.3-16.0), height 8.3% TL (6.4-8.6). Nasal openings large, oblique; nasal flaps weakly developed, pointed, triangular, anterior tip extending across nasal opening. Eyes large, ovalshaped, length 3.8 (3.1-3.9) times into head length and height 6.9 (5.5-6.9) into head length; orbit with anterior and posterior notch. Spiracles semicircular, slightly above dorsal margin of eye, diameter 3.0 (2.7-3.8) times into eye length. Labial furrows short, lower labial furrow length 0.4 (0.5-0.8) into upper labial furrow length. Gill openings relatively small, slightly oblique, in horizontal series, all about equal in height; height of first gill slit 1.1% TL (1.3-2.2). Mouth broad, strongly arched, upper jaw originating below middle of the eye, width 1.3 (1.1-1.2) times into preoral length.

Teeth dissimilar in upper and lower jaws (Fig. 2); upper teeth multicuspid, first row with one to two lateral cusplets on either side of single, pointed median cusp; teeth in lower jaw unicuspid, in single series, not erect, overlapping, with blade-like edge; upper tooth counts numbering 27 (25-30); lower tooth counts numbering 42 (33-36).

[FIGURE 2 OMITTED]

Dermal denticles low, small, truncate, distinctly block-like crowns without any spines, irregularly arranged along head and trunk; denticles on caudal fin more rhomboid in shape and relatively anteriorly oriented; smaller specimens possessing dermal denticles with pointed crowns. Photophore markings concentrated along sides of head and trunk, irregular on rest of body.

Suprapelvic flank photo-markings relatively poorly defined, consisting of anterior branch with no posterior branch, extending forward of pelvic fin origin (Fig. 3). Caudal base photo-marking relatively broad, forming saddle along ventral portion of caudal peduncle; at lower caudal fin origin, base photo-marking extending dorsally to half caudal peduncle height, narrowing to point and forming central caudal photo-marking. Central caudal photo-marking separated from flank photo-markings by at least one length of central caudal marking. Upper caudal photo-marking very narrow, running along ventral edge of lateral line and terminating an open groove posteriorly.

[FIGURE 3 OMITTED]

Distal margins of dorsal fins covered with skin, proximal margins largely covered with dermal denticles. Each dorsal fin possessing grooved spine anterior to dorsal fin origin. First dorsal fin small, slightly rounded apex, length 8.0% TL (8.1-8.5); corresponding spine origin behind pectoral fin rear tip; insertion well forward of pelvic fin origin and closer to pectoral fin insertion; much smaller than length of second dorsal fin, height 2.3% TL (1.7-2.3). First dorsal fin spine slender, relatively straight, length greater than height of corresponding fin; spine of holotype intact upon collection, but subsequently broken off and lost. Free rear tip of fin short, with height being shorter than base of fin. Second dorsal fin larger than first dorsal fin, relatively erect, possessing concave distal margin, free rear tip relatively long; origin behind axis of pelvic fins; second dorsal fin length 11.0% TL (12.2-12.3). Second dorsal fin spine strong, stout, longer than first dorsal spine, greater than height and base of corresponding fin, length 6.7% TL (6.9-8.4); origin behind insertion of pelvic fins, curving strongly rearward. Interdorsal space about three times distance between first dorsal fin spine origin and pectoral axil, slightly smaller than pectoral-pelvic distance; interdorsal space 0.9 (0.9-1.0) into distance from snout tip to pectoral fin origin.

Pectoral fins very narrow, squared, relatively short, with no expanded corners of fins; inner margin straight and anterior margin nearly straight, inner margin 4.6% TL (5.0-6.1). Caudal fin not rounded, with subterminal notch, length of dorsal caudal fin margin 15.4% TL (15.3-19.4); lower lobe shorter, more rounded, preventral caudal fin margin 1.6 (2.1-3.0) into dorsal caudal fin margin.

Spiral valve turns 11. Vertebral numbers: 48 (38-41) monospondylous, 17 (21-24) diplospondylous, 24 (22-25) dorso-caudal, and 89 (84-88) total; transition of monospondylous vertebrae to diplospondylous vertebrae posterior to cloaca.

Coloration: Post-mortem coloration dark, dusky grey dorsally, darker ventrally; dorsal, ventral and lateral surfaces with inconspicuous boundaries; markings weak and located above pelvic fin, origin of lower caudal lobe and on ventral edge of lateral groove; distal margins of fins translucent. Corners of mouth and dorso-posterior margin of eye opening bleached white. White pineal spot present between eyes on dorsal side of head. After preservation coloration light brown to grayish; patchy abrasions along sides of body are probably capture damage and not likely constituting any natural coloration.

Size: Maximum length likely greater than 456 mm TL based on sexual immaturity of the female of that size (when measured fresh; after preservation in 10% formalin and 70% ethanol its length decreased to 435 mm TL). Maximum length of males at least 406 mm TL based on mature male paratype measured after preservation in 70% ethanol.

[FIGURE 5 OMITTED]

Distribution: Holotype and paratypes were collected along the upper continental slope by bottom trawler off north-eastern Taiwan at a depth greater than 300 m.

Biological notes: Sexual maturity of males likely is achieved at a length between 319 mm TL (largest observed immature male) and 406 mm TL (smallest observed mature male). A 456 mm TL female was sexually immature, suggesting that female maturity occurs at an even larger size. A 44 x 20 mm female cymothoid isopod, Elthusa raynaudi (CASIZ 180277), was found attached to the roof of the mouth of the holotype (Fig. 4), filling up most of the oral cavity. This species normally occurs in the gill chambers of fishes and this represents only the third record of this isopod from the northern hemisphere (Williams et al. 2010).

[FIGURE 4 OMITTED]

Etymology: The species is named in honor of Dr. Shoou-Jeng Joung, National Taiwan Ocean University, for his contributions to chondrichthyan research in Taiwan and for his assistance and support during field surveys conducted by DAE and GHB of Taiwanese fish markets.

[FIGURE 6 OMITTED]

[FIGURE 7 OMITTED]

[FIGURE 8 OMITTED]

DISCUSSION

Comparisons: The holotype and paratypes of E. joungi were compared to three paratypes of E. bigelowi (CAS 56056, 2 specimens; CAS 48786) and two syntypes of E. pusillus (BMNH 1855.11.29.27, 2 specimens). In addition, regional non-type material of both species was also compared to the new species. Interestingly, we found the type specimens of both E. bigelowi and E. pusillus not only to differ from E. joungi, but also from congeners from different geographic regions, suggesting a closer examination of regional material may be warranted. The paratypes of E. bigelowi were from the Gulf of Mexico while the non-type material was from Australia, central North Pacific, South Africa and the north-western Hawaiian islands. The syntypes of E. pusillus were from Madeira while comparative non-type material was examined from Angola, Australia, central North Pacific, Gulf of Mexico, South Africa and the north-western Hawaiian Islands.

Etmopterus joungi has relatively evenly-sized gill slit heights, whereas the gills of the type specimens of E. pusillus and E. bigelowi usually decrease in size posteriorly and the gills of the non-type specimens vary in size. Etmopterus joungi possesses an upper jaw dentition with a relatively slender medial cusp and robust lateral cusplets (but not as large as the medial cusp) on either side. Etmopterus pusillus generally possesses an upper jaw dentition with a slender medial cusp with slender lateral cusplets, whereas E. bigelowi generally possesses an upper jaw dentition with a significantly more robust medial cusp with robust lateral cusplets on either side. The lower jaw dentition of E. joungi is also different in that the cusps are significantly more oblique and relatively slender than those found in E. pusillus and E. bigelowi of similar sizes and sexes. Etmopterus joungi has a relatively shorter preoral length [8.0% TL (8.2-8.7)] as compared to the syntypes E. pusillus (9.1-10.1% TL) and the paratypes of E. bigelowi (9.0-10.6% TL). The non-type specimens of E. pusillus measured 8.3-11.0% TL and the non-type specimens of E. bigelowi measured 8.3-12.3% TL. The dermal denticles of E. joungi from much of the body are relatively block-like and lower in height than those of E. pusillus and E. bigelowi, and lack points coming off the central denticle, unlike in its two congeners, which are taller in height and possess small points coming off the central denticle (Shirai & Tachikawa 1993).

Etmopterus joungi is distinguished from E. pusillus based on a combination of several key characteristics including a relatively smaller mouth length at 1.6% TL (1.2-1.9), compared to the syntypes of E. pusillus at 4.2-4.7% and 1.3-2.7% in non-type E. pusillus specimens. E. joungi also possesses a smaller head length than the syntypes of E. pusillus. Head length for E. joungi is 15.4% TL (15.3-16.0), compared to 21.9-24.6% TL for the syntypes of E. pusillus and 12.9-15.6% TL for the non-type E. pusillus specimens.

The posterior margin of the pectoral fin can be used to distinguish these two species with E. joungi having especially short pectoral fins [3.9% TL (4.1-5.4)] compared to the longer pectoral fins of E. pusillus (syntypes: 5.9-7.2% TL; non-types: 3.2-6.1% TL). The dorsal fins of E. joungi can also be used to separate it from the syntypes of E. pusillus in that the first dorsal fin of E. joungi is relatively longer. The first dorsal fin total length is 8.0% TL (8.1-8.5) in E. joungi and 6.0-7.0% TL in the E. pusillus syntypes, with the non-type E. pusillus specimens ranging from 8.1-9.1% TL. The first dorsal fin base length in E. joungi is 4.8% TL (4.4-4.9) compared to 2.3-3.1% TL in the syntypes of E. pusillus. This measurement in non-type material is quite variable with specimens from Australia ranging 4.3-5.1%, the Gulf of Mexico from 3.9-5.1% TL and for South African specimens 4.0-4.5%. The second dorsal fin spine length is also good for distinguishing the two species in that E. joungi has a shorter spine length than the syntypes of E. pusillus; 6.7 (6.9-8.4) % TL and 7.6-9.9 % TL for E. joungi and E. pusillus syntypes, respectively. The second dorsal fin spine length in non-type specimens of E. pusillus ranges from 4.1-7.4% TL.

Compared to E. pusillus, the suprapelvic flank markings in E. joungi are relatively obscure and do not possess the conspicuous borders that are found in E. pusillus. The anterior branch of the flank photo-markings is also significantly shorter in E. joungi. The measurement for the anterior branch length is 11.0% TL (7.6-10.8) in E. joungi and 16.3-18.2% TL for E. pusillus. Etmopterus joungi has a larger interdorsal space than the syntypes of E. pusillus. The measurement of the interdorsal space is 25.5% TL (23.3-25.9) and 20.2-22.9% TL for E. joungi and the syntypes of E. pusillus, respectively. The non-type specimens of E. pusillus have an interdorsal space with a range of 23.3-27.9% TL. Another useful characteristic separating these species is the interdorsal space of E. joungi is about three times the distance between the pectoral fin insertion and the first dorsal fin spine origin, as opposed to E. pusillus, which has a distance less than three times or more (Shirai & Tachikawa 1993).

Etmopterus joungi has a greatly reduced caudal fin subterminal margin compared to the syntypes of E. pusillus, although the non-type specimens show similar lengths to E. joungi. The measurement for this is 2.8% TL (1.7-2.8) for E. joungi and 3.8-5.4% TL for E. pusillus. The non-types measured 1.6-3.0% TL for the caudal fin subterminal margin. Etmopterus joungi also possesses a smaller caudal fin fork width at 5.3% TL (3.8-5.8) than the syntypes of E. pusillus, which have a range of 6.0-7.1% TL. The caudal fin fork of non-type specimens of E. pusillus measures 5.8-8.5% TL.

Etmopterus joungi has fewer monospondylous vertebrae 48 (38-41) than the syntypes of E. pusillus (51-52), and more diplospondylous vertebrae 17 (21-24) than the syntypes of E. pusillus (10-11). Female E. joungi reach sexual maturity at a larger size (largest individual known at 456 mm TL is immature) than E. pusillus (mature at 380 mm TL; Shirai & Tachikawa 1993).

Etmopterus joungi is distinguished from E. bigelowi based on a combination of several key characteristics. Etmopterus joungi differs from E. bigelowi in the morphology of dentition. The upper teeth of E. joungi have one or two lateral cusplets bracketing a relatively slender median cusp. By contrast E. bigelowi of a similar lengths have only a single cusplet on either side of the robust medial cusp. The lower jaw teeth of E. joungi are also relatively oblique and do not grow an erect lower cusp, as is found in E. bigelowi of a similar length. Furthermore, E. joungi have more teeth in both the upper and lower jaws than E. bigelowi. The pectoral fins of E. joungi do not possess the expanded inner margin found in E. bigelowi. The expanded inner margin gives E. bigelowi broader, more rounded pectoral fins than E. joungi. The dorsal fin spines of E. bigelowi are also much straighter than those found in the new species.

A good characteristic for separating these two congeners is the more posterior position of dorsal fins of E. joungi compared to those of E. bigelowi. The measurement for the first dorsal fin to mid-point of pectoral fin insertion is 10.6% TL (11.3-13.8) in E. joungi, but 7.2-9.2% TL in the E. bigelowi paratypes. The non-type specimens have a range of 6.1-8.2% TL. In addition, the first dorsal fin to midpoint of pelvic fin origin is 16.1% TL (12.5-15.8) and 17.2-22.9% TL in E. joungi and E. bigelowi, respectively. Etmopterus joungi has dermal denticles that extend onto the dorsal fins, a characteristic that is not found in E. bigelowi. The holotype of Etmopterus joungi has fewer turns (11) of the spiral valve compared to E. bigelowi (16-19). Etmopterus joungi also possesses fewer monospondylous vertebrae than E. bigelowi, with the range for E. joungi being 48 (38-41) and the range for E. bigelowi being 50-57 (Shirai & Tachikawa 1993).

The high degree of variability between the paratypes of E. bigelowi and the syntypes of E. pusillus compared to their respective non-type specimens indicates that the two species need to be regionally reassessed. The large variability between type and non-type specimens suggests that the two currently recognized species in the "pusillus group" may represent an admixture of species.

ACKNOWLEDGEMENTS

We thank the following individuals for their assistance during the course of this study: Dave Catania and Jon Fong (California Academy of Sciences); William White and Al Graham (CSIRO Marine & Atmospheric Research, Hobart, Tasmania, Australia); Rob Robins (Florida Museum of Natural History); Wade Smith (Oregon State University); Leonard Compagno and Mike Bougaardt (South African Museum); Oliver Crimmen, Patrick Campbell, and James McClaine (British Museum Natural History); and Kazuhiro Nakaya (Hokkaido University Museum of Zoology). We would also like to thank Bert Williams (University of Puerto Rico) for identification of the isopod. DAE and GHB express their gratitude to Shoou-Jeng Joung (National Taiwan Ocean University, Keelung, Taiwan) for his friendship and hospitality during their field trips to Taiwan. This study was supported by funds from NOAA/NMFS to the National Shark Research Consortium, Pacific Shark Research Center, Florida Program for Shark Research, and the David and Lucile Packard Foundation.

Received: 29 April 2010 - Accepted: 23 November 2010

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Table II. Morphometries and meristics of the ranges for the type and
non-type material of Etmopterus bigelowi and E. pusillus, expressed
as % TL.

                    Etmopterus  Etmopterus  Etmopterus  Etmopterus
                     bigelowi    pusillus    bigelowi    pusillus
                    Paratypes    Syntypes   Non-types   Non-types

Total length         325-410mm   l94 326mm   267-678mm   236-505mm

Pre-first dorsal     32.8-36.3   34.7-37.1   32.0-36.8   32.2-37.0
length

Pre-second dorsal    62.6-64.3   62.4-62.6   62.6-67.6   61.0-67.8
length

Head length          14.4-25.2   21.9-24.6   14.9-23.9   12.9-15.6

Pre-branchial        18.0-18.8   17.2-18.9   17.4-21.3   15.8-19.8
length

Pre-spiracle         11.7-13.5   12.1-14.4   11.2-14.2   10.7-13.1
length

Pre-orbital            4.9-6.9     4.8-6.4     4.3-7.7     4.5-6.0
length

Pre-oral length       9.0-10.6    9.1-10.1    8.3-12.3    8.3-11.0

Eye length             3.7-4.5     4.9-5.7     2.8-4.3     2.2-4.7

Eye height             1.8-2.5     3.6-3.6     1.9-2.9     1.6-3.0

Spiracle length        1.1-1.5     1.4-1.6     1.0-2.5     0.8-1.3

Eye spiracle           2.0-2.7     2.6-2.7     1.5-2.4     1.8-2.8
distance

First gill slit        2.2-2.8     1.6-2.5     1.3-2.5     1.0-2.3
height

Fifth gill slit        1.6-2.2     1.4-1.8     1.3-2.3     0.8-2.0
height

Mouth length           1.5-2.4     4.2-4.7     1.6-2.3     1.3-2.7

Mouth width            6.8-7.7     7.1-8.8     6.1-8.1     5.6-7.8

Upper labial           1.2-2.0     1.7-2.5     1.1-2.3     0.6-1.9
furrow length

Lower labial           1.0-1.8     1.4-1.4     1.0-1.9     0.6-1.3
furrow length

Nostril width          1.7-2.2     2.1-2.4     1.6-2.4     1.7-2.5
Interorbital           6.7-8.9     7.1-7.7     7.1-8.4     5.5-8.7
distance

Internarial            2.2-3.2     2.9-3.0     2.6-3.3     2.3-3.0
distance

Head height            6.3-8.5     7.4-7.5     6.7-8.9     6.3-7.2

Head width            9.0-10.5     6.5-9.0    7.6-11.6    8.5-10.7

Pre-pectoral         22.9-24.6   21.7-25.1   21.3-24.8   19.4-24.1
length

Pre-pelvic length    52.6-55.4   54.1-56.7   54.2-63.8   52.3-58.4

Snout-vent           52.9-57.8   58.2-59.2   56.8-61.8   55.9-62.4
distance

Pectoral-pelvic      22.5-26.6   25.5-29.1   24.5-32.0   23.6-33.0
distance

Interdorsal          23.4-28.1   20.2-22.9   24.5-30.2   23.3-27.9
distance

Dorsal-caudal        10.5-11.1   10.1-11.0    8.3-11.0    7.6-11.9
distance

Pectoral fin          8.3-10.2     8.9-9.0    7.7-10.0     7.6-8.9
anterior margin
length

Pectoral fin inner     3.7-5.2     4.3-7.3     3.6-5.8     3.2-5.0
margin length

Pectoral fin           3.7-6.5     5.9-7.2     3.2-7.7     3.2-6.1
posterior margin
length

Pectoral fin base      4.3-5.3     4.6-5.5     3.8-5.5     3.5-4.9
length

First dorsal fin       7.1-9.5     6.0-7.0     8.3-9.9     8.1-9.1
maximum length

First dorsal fin       3.4-4.1     2.3-3.1     4.0-5.6     3.9-5.1
base length

First dorsal fin       3.9-5.3     4.3-4.7     3.8-5.2     3.0-4.8
inner margin
length

First dorsal fin       2.0-2.6     2.1-2.3     1.7-3.2     1.8-2.9
height

First dorsal fin       2.6-2.9     2.2-2.3     2.3-5.9     1.8-3.8
posterior margin

First dorsal spine     3.2-5.4     4.4-5.3      31-4.6     0.4-4.2
length

Second dorsal fin    10.7-11.2    8.9-10.7   10.1-11.6   10.7-11.8
maximum length

Second dorsal fin      5.3-6.3     3.3-4.1     5.0-7.2     5.3-6.2
base length

Second dorsal fin      5.1-5.7     4.8-5.6     4.3-5.8     4.7-5.7
inner margin
length

Second dorsal fin      3.6-4.0     3.3-3.9     3.2-4.1     3.2-3.9
height

Second dorsal          6.1-7.4     7.6-9.9     4.8-7.2     4.1-7.4
spine length

Pelvic fin length     9.6-10.5   10.0-11.2    8.7-11.8    8.8-12.4

Pelvic fin             5.1-6.2     6.1-7.1     4.6-7.4     4.9-7.4
anterior margin
length

Pelvic fin base        6.2-9.0     6.0-6.6     5.7-7.2     5.5-7.4
length

Caudal fin dorsal    19.0-19.5   18.1-22.3   17.5-19.3   16.0-21.2
caudal margin

Caudal fin fork        4.5-7.8     6.0-7.1     6.8-9.4     5.8-8.5
width

Caudal fin           10.0-11.5   10.9-12.6    8.6-10.9    8.7-10.9
preventral margin
length

Caudal fin             2.2-2.9     3.8-5.4     1.7-4.3     1.6-3.0
subterminal margin
length

Caudal fin upper       7.6-8.7     7.8-9.0     6.7-9.0     6.5-9.3
postventral
margin

First dorsal fin       7.2-9.2    8.9-12.6     6.1-8.2    7.6-13.6
midpoint to
pectoral fin
insertion

First dorsal fin     17.2-18.8   14.5-17.9   17.7-22.9   15.1-20.2
midpoint to pelvic
fin origin

Pelvic fin           17.3-20.1   17.8-18.3   17.7-24.4   15.5-22.0
midpoint to first
dorsal fin
insertion

Pelvic fin             4.6-6.3     2.7-5.2     4.5-7.1     4.3-7.4
midpoint to second
dorsal fin origin

Flank                      N/A     5.9-7.5     5.5-6.0     6.7-7.3
photo-marking base
length

Flank                      N/A    8.8-12.3    9.8-10.5    8.1-18.2
photo-marking
anterior branch
length


James D. S. Knuckey (1)*, David A. Ebert (1), (2), (3) and George H. Burgess (4)

(1.) Pacific Shark Research Center, Moss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, California, 95039, USA

(2.) Research Associate, South African Institute for Aquatic Biodiversity, Private Bag 1015, Grahamstown, 6140, South Africa

(3.) Research Associate, Department of Ichthyology, California Academy of Sciences, 55 Music Concourse Drive, San Francisco, California, 94118, USA

(4.) Florida Museum of Natural History, University of Florida, Gainesville, Florida, 32611, USA

* Corresponding author: knuckey.james@gmail.com
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Author:Knuckey, James D.S.; Ebert, David A.; Burgess, George H.
Publication:aqua: International Journal of Ichthyology
Article Type:Report
Geographic Code:9TAIW
Date:Apr 26, 2011
Words:6900
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