Etmopterus marshae, Ebert & Van Hees, 2018

Ebert, David A. & Van Hees, Kelley E., 2018, Etmopterus marshae sp. nov, a new lanternshark (Squaliformes: Etmopteridae) from the Philippine Islands, with a revised key to the Etmopterus lucifer clade, Zootaxa 4508 (2), pp. 197-210 : 198-202

Etmopterus marshae , new species

Marsha’s Lanternshark

( Figures 1–5 ; Tables 1, 2)

Holotype. PNM 15353, 205 mm [213 mm prior to preservation] total length (TL), maturing male, M/V DA-BFAR, otter trawl, bottom type sandy, station BFAR-583, between Luzon Island and Mindoro Island, Philippines, 13°46'12.6” to 13°48'53.4” S, 120°50'54.6” to 120°50'40.2” E, 322–337 m, 30 May 2011 ( Figures 1a, b ).

Paratypes. 10 specimens: CAS 234011 , males (2 specimens) 234 mm TL, mature, 150 mm TL, immature, females (8 specimens) 97–192 mm TL, maturity undetermined, M/V DA-BFAR, otter trawl, bottom type sandy, station BFAR-583, between Luzon Island and Mindoro Island, Philippines, 13°46'12.6” to 13°48'53.4” S, 120°50'54.6” to 120°50'40.2” E, 322–337 m, 30 May 2011 .

Diagnosis. Etmopterus marshae is a relatively small, slender species of linear–denticled Etmopterus that can be separated from its closest congeners within the E. lucifer clade by a combination of characteristics including the length of its luminescent lateral flank marking branches being relatively equal in length; only three other species have anterior and posterior flank branches about equal in length. The new species can be separated from the other species with relatively equal branch lengths, E. burgessi Schaaf-Da Silva & Ebert, 2006, E. evansi Last, Séret & Burgess, 2002 , and E. pycnolepis Kotlyar, 1990 , by a combination of characteristics including a whitish cheek blotch, a purplish lateral body coloration sharply becoming black below line between pectoral and pelvic fins, a distinct pattern of paired dashes along the upper body and between pectoral and pelvic fins, dark and light banding pattern on its caudal fin, and central and upper caudal marking lengths distinctly different from these other three closely related species.

Description. Values expressed as a percentage of total length (TL) for the holotype (PNM 15353), followed by the ranges for 10 paratypes (97–234 mm TL) are presented in Table 1. The following description proportions include the holotype followed by the paratypes in parentheses. Additional descriptive information on ontogenetic differences between the eight larger specimens (150–234 mm TL) and three smaller specimens (97–116 mm TL) is provided.

Body fusiform, trunk sub-cylindrical, width 1.5 (1.1–2.1) in trunk height; head subconical, long, 24.4 (20.7– 23.3)% TL, slightly depressed, height 0.6 (0.6–0.7) times width. Snout moderately long, conical in lateral view, in dorsal view triangular–shaped becoming rounded at snout–tip, head width 9.3 (8.6–12.0)% TL. Eyes oval-shape, large, length 3.8 (3.8–5.3) in head and 2.2 (1.3–1.7) times height of eye; orbits with anterior and posterior notches; moderately spaced, interorbital space 1.3 (1.0–1.4) in width of head; eye length 1.2 (1.4–1.9) times in interorbital distance. Spiracles small, semi-circular, greatest diameter 2.0 (1.0–2.1)% TL, 3.3 (2.2–4.0) times into length of eye, distance to eye 2.4 (1.8–2.8)% TL, eye–spiracle length 0.7 (0.3–0.7) times into height of eye. Nostrils large, oblique, length about equal to internarial width, less than eye diameter; anterior nasal flap reasonably developed, triangular, anterior tip extending across nasal opening, length 0.8 (0.3–1.0) times spiracle length. Gill openings small, narrow, slightly oblique, in horizontal series, heights about equal, except first opening maybe noticeably larger than last four openings, height of first gill slit 1.3 (1.3–2.0) times height of fifth gill opening, intergill length 1.0 (1.0–1.3) times in length of eye. Mouth broad, length 2.0 (2.2–2.7) times in width, slightly arched, width 0.4 (0.7–0.9) times preoral length.

Teeth dissimilar in upper and lower jaw ( Figure 2 ); upper teeth multicuspid in three functional series, functional teeth in lower jaw unicuspid in single series, with at least two series of replacement teeth in upper and lower jaw; multicuspid upper teeth small, perpendicular, with strong central cusp flanked by one or two lateral cusplets on each side, decreasing size distally; first lateral cusplet about one-half height of central cusp, second lateral cusp (if present) much reduced; teeth in lower jaw fused into single row, blade-like, oblique, slightly erect cusp. Tooth count in first row of upper jaw 30 (30–36) and in first row of lower jaw 34 (30–38).

First dorsal fin small, anterior margin slightly curved, rounded at apex, becoming relatively straight posteriorly, length of first dorsal fin 7.8 (7.4–10.6)% TL, origin slightly behind pectoral fin insertion; fin base insertion well forward of pelvic-fin origin; pre–first dorsal length 1.6 (1.6–2.0) times interdorsal distance; firstdorsal-fin spine slightly curved near tip towards fin apex, height about equal to fin height, 1.0 (0.6–1.0) times into height of first dorsal fin, located behind pectoral fin rear margin. Second dorsal fin conspicuously larger than first dorsal fin, length of first dorsal fin 0.6 (0.6–0.8) times second dorsal fin, height of first dorsal fin 0.6 (0.5–0.9) times second dorsal fin; apex rounded, posterior margin sharply notched, free rear tip elongated, length 12.7 (10.9– 13.7)% TL, pre–second dorsal length 2.9 (2.7–3.5) times interdorsal distance; second-dorsal-fin spine large, height slightly higher than fin height, relatively straight, except slightly curving near tip towards fin apex; origin over insertion of pelvic fins, forward of pelvic fin free rear tips. Interspace between first and second dorsal fins 0.8 (0.6– 0.9) times prepectoral length.

Pectoral fins relatively large, length 9.3 (8.6–10.7)% TL, subangular at free rear tips, base 2.3 (1.4–2.6) times in anterior margin, posterior margin frayed. Caudal peduncle length from second dorsal fin insertion to caudal origin relatively long, 14.1 (11.5–14.7)% TL, height about equal to or slightly greater than width, rounded, and tapering posteriorly; less than upper caudal fin length. Caudal fin elongated, slightly less than head length, subterminal notch relatively inconspicuous; length of lower preventral caudal fin margin less than one-half upper caudal fin margin.

Dermal denticles hook-like, posteriorly directed rearwards; organized in distinct longitudinal rows laterally, characteristic of E. lucifer clade members. Distance between lateral rows uniformly even, not decreasing from dorsal head surface rearwards towards caudal peduncle. Ventral snout surface densely and uniformly covered with dermal denticles, except for bare area surrounding mouth region ( Figure 3 ); pores (ampullae of Lorenzini) obscured by dense dermal denticle covering snout surface. Dorsal fins, including ceratotrichia, uniformly covered with longitudinal rows of dermal denticles extending continuously onto each from body trunk. Flank-mark-area denticles uniformly dense and pointed ventrally. Dorsal surface of individual denticles without distinct keel.

Luminescent markings distinct, intricate; ventral head surface markings blackish, starting just posterior to and slightly lateral to snout tip, extending to level of nostrils and orbits at about anterior notch, descending below eye level to mouth, then extending upwards over mouth corners and encircling mouth; continuous with belly marking posterior to mouth at about first gill openings, demarcated by a faint band of transverse dermal folds across throat extending from below lower edges of first two gill openings on either side. Head dorsal surface photophore pattern faint, originating at about spiracles as single midline along back and flanked on each side by a row, and extending in parallel posteriorly to caudal fin origin.

Belly marking originates behind mouth on posterior portion of transverse dermal folds and extends ventrally along pectoral fin bases slightly extending upwards to about level with fin base insertion, about level with ventral edges of gill openings, and posteriorly to pelvic fin bases; ventral surface of pectoral fin lighter along lower base and upper base where ceratotrichia originate, bisected by thin darker band; margin on pectoral–pelvic space clearly defined, line extending from rear margin of pectoral fin base nearly to pelvic fin insertion except for light to whitish mark at pelvic fin origin; dark ventral belly surface continuous onto caudal peduncle to about lower caudal fin origin ( Figure 4 ).

Flank markings well defined, consisting of both an anterior and a posterior branch of roughly even length; anterior branch length 9.3 (7.3–10.7)% TL, slender, nearly straight except slightly curving near anterior tip, stopping just before origin of pelvic fin; posterior branch noticeably curved above pelvic fin and thick, width at level of base end of second dorsal fin 2.9 (2.0–4.3)% TL, branch length 8.8 (7.8–10.7)% TL, extending just to distal free rear tip of second dorsal fin; origin anterior to pelvic fin insertion. Caudal base marking distinct, narrow, length 5.9 (1.5–2.5) times longer than base of flank marking. Upper caudal fin marking very narrow, its length 1.2 (0.6–0.9) times upper caudal marking.

Vertebral counts: total count 81 (74–85); total precaudal count 58 (51–61); monospondylous 39 (35–40); diplospondylous precaudal 19 (14–22); caudal 23 (21–24).

Ontogenetic differences between large and small specimens. Etmopterus marshae sp. nov. exhibits several subtle changes with growth between the three smallest specimens (97–116 mm TL) and the eight largest individuals, including the holotype (150–234 mm TL), the largest of which is an adult male. The following character differences between large and small type specimens included: prenarial length 3.9–4.1% vs 2.0–2.6% TL, preoral length 10.8–11.3% vs 9.3–10.9% TL, preorbital length 6.9–7.2% vs 5.3–6.8% TL, orbit length 5.2–6.9% vs 4.2–5.6% TL, orbit height 4.9–5.2 vs 3.0–4.0% TL, interorbital length 8.8–10.3% vs 7.3–8.7% TL, spiracle length 2.1–2.9% vs 1.0–2.1% TL. The coloration was more pronounced in the smaller individuals, but overall the color patterns were consistent in both size groups.

Coloration. Etmopterus marshae in life is a dark purplish black dorsally and laterally on body trunk, becoming dark black ventrally; transition between lateral and ventral surfaces sharply demarcated, becoming distinctly black from ventral surface of snout tip to about midpoint of anterior eye notch, extending semi-circular below eye orbit, and from below posterior eye notch extending posteriorly to pectoral fin origin; distance between pectoral-pelvic fin length sharply demarcated except for lighter areas behind pectoral fin insertion and pelvic fin origin; distance between pelvic fin insertion and lower caudal fin origin lighter except for flank marking base behind pelvic fin insertion and dark black blotch between posterior flank marking and caudal fin base marking ( Figure 1a ). Eyeball a solid greenish. Faint white spot on each cheek located just behind eye. Dorsal view of body surface uniformly dark, without lighter or white stripe; prominent complex pattern of dashes along body trunk with 1–3 rows of dark dashes extends from above dorsal head surface above lateral line to caudal origin, with a separate paired row of dashes extending between pectoral and pelvic fins. Gills and area just above them purplish to lighter, but area below sharply demarcated to black. Pectoral and pelvic fins dark at base and along anterior fin edge, becoming translucent to white on remainder of fins. Dorsal fins purplish black to black at base and along anterior edges, becoming translucent to white on remainder of fins. Black lateral flank markings sharply demarcated by surrounding lighter colored lateral flanks; prominent lighter colored flank area extending dorsally approximately length of darker lateral flank markings; lighter purplish colored flank area extending on either side of dark-flankmarking base located just posterior to pelvic fins; prominent lighter colored flank area originates anterior to darkflank-base marking and extends anteriorly to about pectoral fin insertion; lighter colored flank area posterior to dark flank base and below posterior branch of lateral lighter flank coloration noticeable, but not as prominent as faint whitish flank area between pectoral and pelvic fins. Lateral lighter colored flank area between pectoral and pelvic fins sharply demarcates lateral and ventral surfaces; ventral surface black. Prominent black blotch between posterior tip of flank marking and lower caudal origin. Caudal fin with distinct dark black bar originating at upper caudal fin origin and fading posteriorly to a lighter or white, and with a prominent black caudal fin tip; upper and lower ventral lobe mostly black. Ventral surface mostly dark black around mouth and belly. A dark stripe originates between pelvic fin insertions and extends to caudal origin. Area around mouth distinctly black, surface bare of dermal denticles, sharply demarcated from coarse dermal denticles surrounding it. After preservation coloration similar except purplish coloration fades to light or dark brown; dorsal white stripe, white cheek spot, and whitish flank area and black lateral flank markings prominent; dark bar on caudal fin and darker dashes extending laterally on body still clearly visible; area around gills becoming whitish ( Figure 1b ).

Size. A 234 mm TL male (CAS 234011) was mature, while a 213 mm TL male (Holotype PNM 15353) was maturing. The largest female was 192 mm TL, but its maturity was not determined. Birth size uncertain, although the three smallest paratypes ranging 97–116 mm TL all had umbilical scars, with the umbilical scar slightly open on the smallest specimen, suggesting that this individual was close to birth size.

Distribution. The new species is known from 11 specimens collected on a single haul between the Philippine islands of Luzon Island and Mindoro (13° 46’ 12.6”E 120° 50’ 54.6”S to 13° 48’ 53.4”E 120° 50’ 40.2”S), and at a depth range of 322–337 m ( Figure 5 ). The bottom type where the specimens were collected was sandy.

Etymology. The species is named after Marsha Englebrecht for her innovative contributions to the field of elasmobranch husbandry. The proposed common name is Marsha’s Lanternshark.

Figures

FIGURE 1. Etmopterus marshae new species, lateral view of holotype (PNM 15353, male 213 mm TL), (A) fresh; (B) postpreservation.

FIGURE 2. Tooth morphology of upper and lower teeth of immature male holotype (PNM 15353).

FIGURE 3. Dermal denticle arrangement on ventral snout surface of Etmopterus marshae (holotype, PNM 15353).

FIGURE 4. Ventral flank marking between pelvic fins and lower caudal origin of Etmopterus marshae new species (holotype, PNM 15353).

FIGURE 5. Distribution map of Etmopterus marshae new species from the Philippines.