Rev. Biol. Trop. 49 Supl. 1: 29-37, 2001

A New Species of Nezumia (Gadiformes: Macrouridae) from Fieberling Guyot, Eastern North Pacific Ocean

Raymond R. Wilson, Jr. Department of Biological Sciences, California State University, Long Beach, Long Beach, CA90840-3702, fax (562) 985- 8878, email: [email protected]

Received: 23-VI-2000 Corrected: 23-XI-2000 Accepted: 8-XII-2000

Abstract: A new species of the macrourine genus Nezumia is described from specimens collected from the crest of Fieber- ling Guyot in the eastern North Pacific Ocean. The new species is distinguishable from all other Nezumia species chiefly on the basis of a high number of pelvic fin rays, a relatively high number of first dorsal fin soft rays, a steep blunt snout lacking scales ventrally, a relatively weak suborbital ridge, and a moderately long, thin barbel. Although possibly endem- ic to the Baja California Seamount Province, the new species appears to lack close relatives among the other Nezumia species of the eastern North Pacific Ocean. It might have arrived there either from a disjunct Tethyan distribution, thus retaining close relatives among the Atlantic Ocean species of Nezumia, or by way of stepping-stone dispersal from the Indo- west Pacific Ocean.

Keywords: Biogeography, Grenadiers, Macrourids, Malacocephalus, Seamounts, Guyots

Nezumia is among the three most spe- macrourids they collected from Fieberling ciose genera of macrourine grenadiers with Guyot (ca. 550 m crest depth) were reported more than 46 described species worldwide as Malacocephalus laevis and as an undeter- (Cohen et al. 1990); however, only six species mined species of Nezumia (listed as Nezumia are reported from the eastern North Pacific sp.1). M. laevis was reported in extraordinar- Ocean (Iwamoto 1979). The typical habitat of ily high abundance whereas Nezumia sp. 1 Nezumia species is upper to middle continen- was reported in moderate abundance. Subse- tal slopes. A few are occasionally collected quently, between 1990 and 1991, Fieberling from slopes of volcanic islands, crests of sub- Guyot was the focus of a coordinated study marine ridges, and isolated seamounts (Oka- on the physical and biological oceanography mura et al. 1982, Sazonov 1985, Wilson et al. of isolated seamounts. During this study sub- 1985, Wilson and Kaufmann 1987, Sazonov mersible observations (Levin et al. 1994) and Iwamoto 1992). Two decades ago the confirmed that, collectively, macrourids were Kaiyo Maru, a research vessel of the Japan indeed very abundant on the crest of Fieber- Fisheries Agency, sampled seamounts of the ling Guyot. Additional sampling by K.L. Fieberling-Guadalupe seamount chain (Batiza Smith and party of the Scripps Institution of 1989) off Baja and southern California (Japan Oceanography provided several macrourid Fisheries Agency Report 1979). The two specimens for direct examination. Among 30 R E V I S TA DE BIOLOGIA T R O P I C A L

those specimens were M. laevis and one Nezumia kensmithi new species undescribed species of Nezumia, probably Blunt-nosed grenadier Fig. 1 Nezumia sp.1. Due to an interest in the ichthyofauna of seamounts, it is my purpose Holotype: SIO92-108; a female of 346+ mm of in this paper to describe and name this new total length, 108.7 mm preanal length, and 71.6 mm head length. Captured at 555 m depth on the summit of Nezumia species, officially adding it both to Fieberling Guyot, 32º27.82’N, 127º47.00’W, in a free- the ichthyofauna of the eastern North Pacific vehicle fish trap set by K.L. Smith and party, 5 October Ocean, as well as to that reported from 1990, aboard the R/V New Horizon. seamounts worldwide (Kaufmann and Wilson Paratypes: SIO92-108 3(310+ to 398 mm total length) (specimens were caught in the same trap as the 1991). holotype); SIO92-110 1(362 mm total length); SIO 93- 186 5(285+ to 340 mm total length). MATERIALS AND METHODS Diagnosis: A macrourine grenadier of Specimens of Nezumia were obtained the genus N e z u m i a as characterized by from the crest of Fieberling Guyot using bait- Iwamoto (1979) and Cohen et al. (1990) with ed, free-vehicle traps as in Smith et al. (1979). 11-12 pelvic fin rays, 9-11 first dorsal fin soft Specimens were initially frozen, then ten rays, a steep, blunt snout naked on the venter, were fixed in formalin and subsequently a relatively weak suborbital ridge, and a mod- transferred to 55% isopropanol. Methods for erately long, thin barbel. making counts and measurements followed Description: Holotype counts (Table 1; Iwamoto (1970). Counts of rays in both column 1): First dorsal fin iI-10; P1 21i, P2 pelvic fins were made. Otherwise, counts 12/12i, scales below origin of first dorsal fin were taken from the left side of the body 9, scales below origin of second dorsal fin 9. whenever possible. Sagittae were removed Holotype measurements in % of head length: from three of the above specimens and mea- snout length 27.0, internasal width 18.2, bar- sured as in Wilson (1985). bel length 16.7, interorbital width 20.3, Comparative eastern Pacific Ocean material orbital diameter 29.6, suborbital width 13.6, examined: Nezumia convergens SIO72-184 3(180 to ventral snout length 16.7, upper jaw length 203 mm total length); Nezumia stelgidolepis SIO62-188 13(315 to 400 mm total length) and SIO89-42 16(104 to 39.5, length at preopercular orbital angle 204 mm total length); Nezumia pudens CAS38310 1(405 40.2, postorbital length 50.1; measurement in mm total length), CAS38323 2(115 to 235 mm total % of preanal length: head length 65.9; mea- length), SU22727 1(334+ mm total length); Nezumia surement in % of total length: preanal length puchellus CAS38323 3(198+ to 265 mm total length). Otoliths: Sagittal otoliths were removed ca. 31.4. Paratype counts (Table 1, speci- from three specimens collected in baited traps mens of SIO92-108, SIO92-110, and SIO93- on Fieberling Guyot in 1990. These speci- 186, in columns 2 to 10, respectively): first mens ranged from 310+ to 393 mm of total dorsal fin (iI 9-11), P1 (19-25), P2 length. Head lengths ranged between 71.6 (11/12–12/12), scales below origin of first and 75.7 mm (Table 1, specimens 1, 2, and 3). dorsal fin (8-9), scales below origin of sec- Length (anteroposterior axis), height ond dorsal fin (8-9). Paratype measurements (dorsoventral axis), and width (mediolateral in % of head length determined from data in axis) were measured. Lengths were 11.7 to Table 1 (columns 2-10) were: snout length 12.9 mm left sagittae (11.8 to 13.0 mm right), (25-29), barbel length (16-20), interorbital heights 6.8 to 7.5 mm left sagittae (6.1 to 7.4 width (21-25), orbit diameter (27-31), subor- mm right), widths 2.2 to 2.6 mm left sagittae bital width (12-16), ventral snout length (14- (2.2 to 2.6 mm right), and mass 190-260 mg 19), upper jaw length (34-39), length at pre- left sagittae. opercular orbital angle (38-47), postorbital I N T E R N AT I O N A L J O U R N A L OF T R O P I C A L B I O L O G Y AND CONSERVAT I O N 31

Fig. 1. Holotype of Nezumia kensmithi, SIO92-108. length (45-50); measurement in % of preanal both limbs. Gill filaments well developed, length: head length (61-74); measurement in their length about 0.85 in suborbital width in % of total length: preanal length (25-32). holotype. Body scales densely covered with Head moderately compressed, ridges of s l e n d e r, sharply pointed, erect spinules head not prominent. Suborbital region nearly aligned mostly in convergent rows. Scales flat but with weakly developed suborbital below origin of second dorsal fin with about ridge extending from preopercle posterior of 13 spinule rows in holotype, 6 to 7 spinules in orbit to just anterior of nares (Fig. 1). Area longest rows. Head mostly covered with immediately below ridge scaled but becom- firmly-attached scales with reduced spinula- ing naked in narrow strip along ventral mar- tion. Scales dorsal of suborbital ridge gin of lacrimal. Snout very blunt, nearly ver- arranged in two rows with those along margin tical in profile, not protruding much beyond of orbit more columnar shaped. Scales ven- mouth, naked below dorsal tip. Blunt scutes tral of ridge much smaller, not arranged in at tip and lateral angles, not prominent nor distinct rows. Mandible scaled, gill mem- especially spinuous. Barbel not long nor branes naked. Small teeth in wide indistinct especially thick, tapering to fine tip. Interop- bands in upper and lower jaws. Outer row of ercle exposed posteriorly and ventrally with enlarged, recurved teeth in upper jaw. small patch of scales at posteroventral corner, Fins of moderate size. First dorsal fin but otherwise naked. Dorsal margin of oper- with two spines; first spine reduced, barely cle not forming prominent ridge, nor tab-like reaching above body margin; second spine over pectoral shoulder. Posterior margin of long with filamentous tip and series of very opercle nearly straight from posterodorsal short spines along anterior margin; dorsal soft corner; lower third slightly concave, distal rays 9 to 11 (10 in holotype). Second dorsal margin more-or-less triangular. Gill rakers on fin reduced as typical for macrourines. Pec- first arch much reduced, barely visible above toral fins of moderate length, extending pos- gill arch in some specimens, 7 to 9 total on terior of anal fin insertion. Pelvic fins insert- 32 R E V I S TA DE BIOLOGIA T R O P I C A L

Fig. 2. A pair of sagittal otoliths from a Nezumia kensmithi (Table 1, column 3) of 73.0 mm head length. View is of the medial side for both. At left is the right sagitta with rostrum at top, rounded postrostrum at bottom, smooth ventral mar- gin at left, and irregular dorsal margin at right. Dimensions of the left sagitta (at right) are: length 11.7 mm, height 6.81 mm, width 2.20 mm, and mass 190 mg. ed slightly in advance of pectoral origin. Smith, Jr. who, throughout his distinguished Outer pelvic rays with filamentous tips research career in deep-sea biology, has con- extending posterior to anal fin insertion. tributed significantly to our knowledge of the Anus slightly less than half the distance from ecology and behavior of deep-sea fishes, par- pelvic insertion to origin of anal fin. ticularly macrourids, and to our general Periproct between pelvic fins, not extending knowledge of the biology of Pacific Ocean anterior of pelvic fin insertion. Anterior der- seamounts, including Fieberling Guyot. mal window of light organ small, more or less Comparisons: N. kensmithi can be dis- circular, posterior to pelvic fin insertion. tinguished from other macrourids of the east- Otoliths (sagittae) relatively large as is ern North Pacific Ocean having seven bran- typical for macrourids; well defined sulcus chiostegal rays in the key of Iwamoto (1979). along anteroposterior axes. Ventral margins The few gill rakers present on the first arch of smooth, rounding slightly from anterior ros- N. kensmithi (i.e., 7 to 9) causes it to key out trum to posterior margin (Fig. 2). Dorsal to N. convergens in couplet 13a. However, N. margins more irregular. Lateral face slightly kensmithi has more pelvic fin rays (11 to 12 concave. Mean dimensional ratios (N=3 from versus 10 to 11), a much weaker suborbital left sagittae): sagitta length/head length 0.16 ridge, scales below the ridge (naked in N. (range 0.16-0.17), sagitta height/sagitta convergens), and is much less slender. Com- length 0.57 (range 0.55-0.58), sagitta pared to the only remaining congener known width/sagitta length 0.20 (range 0.19-0.22), in the eastern North Pacific Ocean, N . and log sagitta mass/sagitta length 0.19 pudens, N. kensmithi has more pelvic fin rays (range 0.19-0.20). (11 to 12 versus 10 to 11), a shorter and more Freshly thawed specimens with posterior slender barbel, longer gill filaments on the bo d y , nape along interorbit, and snout slate first gill arch, and is naked below the scutes brown; suborbital area gray. Mid-body bluish on the anterior part of the snout (partially black beneath first dorsal fin and bluish along scaled in N. pudens). Among the other side of abdomen and ventrum. Gill mem- described species of Nezumia outside the branes, periproct, lips and posterodorsal corner eastern North Pacific Ocean, N. kensmithi of opercle black. Paired fins black, first dorsal would fall into group F in the key of Cohen et fin dusky with some gray. Anal fin dusky. al. (1990) by having 12 rays in the pelvic fins. Etymology: Named for Dr. Kenneth L. But it differs from all of the group F species I N T E R N AT I O N A L J O U R N A L OF T R O P I C A L B I O L O G Y AND CONSERVAT I O N 33

Fig. 3. Probable distribution of Nezumia kensmithi among seamounts of theBaja California Seamount Province based on the reported collections of Nezumia sp. 1 by the Kaiyo Maru, and specimens obtained from Fieberling Guyot. Named seamounts are as follows: E = Erben Tablemount, F = Fieberling Guyot (type location for N. kensmithi) S = Stoddard Seamount, J = Jasper Seamount. G is Guadalupe Island included only for reference, has no reports of N. kensmithi. in having a very blunt snout and naked venter. sagittae of C. acrolepis average about 12% of Other species of Nezumia with such blunt head length (Wilson 1985). Wilson (1985) snouts and naked venters have fewer (8-10) and Lombarte and Lleonart (1993) have pelvic fin rays. shown that among grenadiers and hakes, The sagittae of N. kensmithi are typical species with the shallowest distributions have of relatively shallow-dwelling macrourids as the largest sagittae, and species with the deep- illustrated by Wilson (1985) in being relative- est distributions have the smallest sagittae. ly thin without any apparent doming. The One explanation for the unusually large sagit- shape more closely resembles tae of N. kensmithi might be that the adult fish Coryphaenoides acrolepis sagittae than sagit- essentially remain on or near the shallow tae of the Nezumia species studied by Wilson crest of the guyot, rather than seeking deeper (1985). The similarity is also apparent in the water with increasing size. Individuals there- dimensional ratios, especially with regard to fore spend perhaps all of their adult life spans log sagitta mass/sagitta length and sagitta at relatively shallow depths over the height/sagitta length. Moreover, at 16 to 17% seamount. of head length the sagittae of N. kensmithi are Distribution: N. kensmithi is presently considerably larger than sagittae of other confirmed only on Fieberling Guyot in the Pacific Ocean macrourids that have been eastern North Pacific Ocean. Fieberling is studied. For example, the notoriously large the penultimate seaward guyot of the Fieber- 34 R E V I S TA DE BIOLOGIA T R O P I C A L I N T E R N AT I O N A L J O U R N A L OF T R O P I C A L B I O L O G Y AND CONSERVAT I O N 35 ling-Guadalupe seamount chain (Batiza Etmopterus sp. and M. laevis are little known 1989), lying about 900 km WSW of San from the California slope. Both are apparent- Diego, California, U.S.A. (Fig. 3). The dis- ly widespread in mid- to low-latitude seas tribution of Nezumia sp. 1, presumably N. except in the eastern North Pacific Ocean and kensmithi, as reported by researchers of the thus would appear to represent the “wide- Kaiyo Maru extendsto other seamounts in the spread” category of Wilson and Kaufmann Baja California Seamount Province of which (1987). But the “widespread” category of the Fieberling-Guadalupe seamounts repre- Wilson and Kaufmann (1987) applied to sent but a few. Nezumia sp. 1 was reported on species widespread throughout the major Erben Tablemount (32o52’N, 132o30’W), the ocean region in which the seamounts ultimate seaward guyot of the Fieberling- occurred as well as beyond it. The distribu- Guadalupe chain, Stoddard Seamount tions of Etmopterus sp. and M. laevis are probably substantially greater outside the ( 3 1o45’N, 126o15’W), Jasper Seamount ocean region (eastern North Pacific) of o o ( 3 0 25’N, 11 2 45’W), and an unnamed Fieberling Guyot than within it. On this rela- seamount lying at 350 m crest depth at tively fine distinction the two might be refer- 23o05’N, 124o55’W (Japan Agency Report able instead to the “exotic” category of Wil- 1979). son and Kaufmann (1987). This category comprised the smallest fraction of the fauna DISCUSSION pool (< 4% of species) of the major seamount groups that had been studied. However, very N. kensmithi does not appear closely little of the data reviewed by Wilson and related to any Nezumia species of the eastern Kaufmann (1987) came from seamounts in Pacific Ocean based on morphological simi- the eastern North Pacific Ocean near the lati- larity. Its steep blunt snout and naked venter tude of Fieberling or lower, so their some- render it superficially close to the Atlantic what artificial categories might not be direct- Ocean species Nezumia atlantica and Nezu - ly extendable to species of the Baja California mia africana, an observation enticing specu- Seamount Province. The conventional inter- lation that N. kensmithi might be a product of pretation would be to regard the two wide- a disjunct Tethyan distribution. Conversely, spread species as extralimital to the eastern there is evidence of possible origination in the North Pacific Ocean. Indo-west Pacific Ocean via the eastern South The two most abundant and probably Pacific Ocean. Wilson and Kaufmann (1987) most widespread fishes collected from reported that the ichthyofauna of seamounts Fieberling Guyot (M. laevis and Etmopterus with crests at moderate depths (e.g., 200 to sp.) are possibly extralimital in the eastern 2000 m) is typically composed of nearly North Pacific Ocean from a chiefly Indo-west equal parts of widespread species and species Pacific Ocean distribution. The third most abundant on the nearest continental slope abundant species collected there by the Kaiyo (i.e., provincial species). The other demersal Maru, Nezumia sp. 1 (= N. kensmithi) might fishes reported from the crest of Fieberling be endemic to the Baja California Seamount (Japan Agency Report 1979) included the Province, but there are no closely-related hagfish Eptatretus deani, the catshark Apris - congeners reported from the eastern North turus brunneus, the squaloid Etmopterus sp. Pacific Ocean. The abundant demersal fishes (E. cf. granulosus?), the scorpaenids Sebas - of Fieberling Guyot reflect a larger pattern of tolobus altivelis and Sebastes sp., and M. lae - dominance of mid- to low-latitude seamounts vis. While E. deani, A. brunneus, S. altivelis, in the central and eastern Pacific oceans by and Sebastes sp. are certainly eastern Pacific species also abundant in the Indo-west Pacif- (provincial) species of the California slope, ic Ocean (Hubbs 1959, Wilson et al. 1985, 36 R E V I S TA DE BIOLOGIA T R O P I C A L

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