Three New Species of the Genus Photonectes (Teleostei: Stomiiformes: Stomiidae: Melanostomiinae) from the Pacific Ocean Cynthia Klepadlo 1 Three new species of the mesopelagic fish genus Photonectes (Stomiidae, Melanostomiinae, subgenus Photonectes) are described from the Pacific Ocean with species descriptions augmented by new characters: origin of the IP-photophore series, gill-filament length, and jaw-tooth length. Photonectes coffea, new species (central equatorial, north, and western Pacific) has an elongate barbel with two bean-shaped light organs; IV photophores 37–39; dorsal-fin rays 12– 13; no blue luminous tissue; one white luminous shoulder spot; all jaw teeth small canines; and gill filaments on first arch extending beyond opercular opening. Photonectes barnetti, new species (North Pacific Gyre) has an elongate barbel with a single ovoid bulb and a white area along the stem; IV photophores 37–39; dorsal-fin rays 13–15; no blue luminous tissue; one or two white luminous shoulder spots; jaw teeth of variable length; and reduced gill filaments on first arch. Photonectes corynodes, new species (central equatorial Pacific) is known from a single specimen and has a barbel with a single hourglass-shaped bulb and a bifid terminal filament, both branches ending in small light organs; IV photophores 34; dorsal-fin rays 15; no blue luminous tissue or white luminous shoulder spots; jaw teeth of variable length; and gill filaments neither reduced nor elongated. A key to the subgenus Photonectes is provided. S TOMIID fishes of the subfamily Melanostomiinae (or scaleless black dragonfishes; Nelson, 2006) are elon- gate deep-sea predators with two ventrolateral rows of photophores, canine teeth, and no true gill rakers as adults. Small secondary photophores are often present on the head, body, and fin rays; clusters or spots of luminous tissue may occur around the head, on the caudal peduncle, or on the lateral surface of the body. The chin barbel can be very small to long, simple to complex. The dorsal and anal fins are opposite and set far posteriorly on the body (Morrow and Gibbs, 1964; Harold, 2003; Nelson, 2006). The genus Photonectes is separated from all other melano- stomiine genera by the following combination of characters: the lower jaw is longer than the upper and strongly curved dorsally; the snout is short and abrupt; teeth are present on the vomer; the pectoral fin has 0–3 rays; a large postorbital light organ but no suborbital light organ; and the mesocor- acoid is present but unossified or absent (Morrow and Gibbs, 1964; Fink, 1985; Harold, 2003). Several species have one or two white luminous spots at the upper end of the opercular opening (‘‘shoulder spots’’); a specimen of P. margarita (Scripps Institution of Oceanography SIO 98-5) has addition- al spots on the lateral surface of the body and on the caudal peduncle. Some species of Photonectes have two lines of what is referred to as blue luminous tissue along the ventral midline from the isthmus to the anal-fin origin (Morrow and Gibbs, 1964); short transverse branches may be present between each PV photophore, and small patches may occur along the isthmus, lower jaw, and end of the maxillary (Morrow and Gibbs, 1964). The barbel bulb and postorbital light organ have been reported to produce light with various colors in freshly caught specimens (Beebe and Crane, 1939). Paxton (pers. comm.) noted the barbel bulb in a freshly caught specimen displayed different colors in incandescent light than it did in UV light; these color differences have been previously reported by Beebe and Crane (1939). Of the 22 nominal species described for Photonectes, 12 are considered valid and are placed in four subgenera following Morrow and Gibbs (1964) based on the presence or absence of black skin covering the dorsal- and anal-fin rays, the pelvic-fin insertion closer to either the caudal-fin base or the snout, and the number of IV (IP + OV, isthmus to pelvic fins) photophores (Table 1). The three new species are placed in the subgenus Photonectes based on the following combina- tion of characters: pectoral fins absent, pelvic fins inserted closer to the caudal-fin base, dorsal- and anal-fin rays not covered by black fleshy tissue, and IV photophores 30–39. Species of Photonectes are distinguished mainly by differ- ences in the barbel structure, presence or absence of extra luminous tissue spots, and presence or absence of blue luminous bands or spots (Morrow and Gibbs, 1964), any of which may be damaged or destroyed during collection. This study found additional characters useful for identification of species: IP (isthmus) photophore origin (extending the full length of the isthmus or beginning posterior to the mandibular symphysis after a gap of approximately 50% of the isthmus length; Fig. 1B, 1C), gill-filament length (Fig. 2), and tooth length (Fig. 3). MATERIALS AND METHODS Measurements were made with vernier calipers to the nearest 0.1 mm and include: standard length (SL), head length (HL), barbel length, and lengths from snout to pelvic fin (Sn–V), from pelvic fin to vent (V–vent), and from vent to base of caudal fin (vent–C). Percent of SL (% SL) was also calculated and is given in Table 2. Due to the limited number of specimens, standard deviations were not calcu- lated and, by SIO Collection policy, dissections were not made for sex determination. Meristic data include fin rays, teeth, and lateral and ventral photophores. Tooth counts are reported as premaxillary, maxillary, mandibular, vomerine, palatine, and basibranchial; maxillary teeth are divided into ‘‘erect’’ (anterior canines) and ‘‘oblique’’ (posterior series of very small inclined teeth). Photophore terminology (Fig. 1) follows Morrow and Gibbs (1964). Institutional abbrevia- tions are as listed at http://www.asih.org/node/204. Gill-filament length on first branchial arch (Table 1) is defined as ‘‘reduced’’ (less than one-half arch depth; Fig. 2A), ‘‘normal’’ (longer than arch depth but not extending beyond opercular opening; Fig. 2B), or ‘‘very 1 Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0208; E-mail: [email protected]. Submitted: 7 October 2009. Accepted: 22 November 2010. Associate Editor: W. L. Smith. F 2011 by the American Society of Ichthyologists and Herpetologists DOI: 10.1643/CG-10-184 Copeia 2011, No. 2, 201–210
Transcript
Three New Species of the Genus Photonectes (Teleostei: Stomiiformes:
Stomiidae: Melanostomiinae) from the Pacific Ocean
Cynthia Klepadlo1
Three new species of the mesopelagic fish genus Photonectes (Stomiidae, Melanostomiinae, subgenus Photonectes) aredescribed from the Pacific Ocean with species descriptions augmented by new characters: origin of the IP-photophoreseries, gill-filament length, and jaw-tooth length. Photonectes coffea, new species (central equatorial, north, andwestern Pacific) has an elongate barbel with two bean-shaped light organs; IV photophores 37–39; dorsal-fin rays 12–13; no blue luminous tissue; one white luminous shoulder spot; all jaw teeth small canines; and gill filaments on firstarch extending beyond opercular opening. Photonectes barnetti, new species (North Pacific Gyre) has an elongate barbelwith a single ovoid bulb and a white area along the stem; IV photophores 37–39; dorsal-fin rays 13–15; no blue luminoustissue; one or two white luminous shoulder spots; jaw teeth of variable length; and reduced gill filaments on first arch.Photonectes corynodes, new species (central equatorial Pacific) is known from a single specimen and has a barbel with asingle hourglass-shaped bulb and a bifid terminal filament, both branches ending in small light organs; IV photophores34; dorsal-fin rays 15; no blue luminous tissue or white luminous shoulder spots; jaw teeth of variable length; and gillfilaments neither reduced nor elongated. A key to the subgenus Photonectes is provided.
STOMIID fishes of the subfamily Melanostomiinae (orscaleless black dragonfishes; Nelson, 2006) are elon-gate deep-sea predators with two ventrolateral rows of
photophores, canine teeth, and no true gill rakers as adults.Small secondary photophores are often present on the head,body, and fin rays; clusters or spots of luminous tissue mayoccur around the head, on the caudal peduncle, or on thelateral surface of the body. The chin barbel can be very smallto long, simple to complex. The dorsal and anal fins areopposite and set far posteriorly on the body (Morrow andGibbs, 1964; Harold, 2003; Nelson, 2006).
The genus Photonectes is separated from all other melano-stomiine genera by the following combination of characters:the lower jaw is longer than the upper and strongly curveddorsally; the snout is short and abrupt; teeth are present onthe vomer; the pectoral fin has 0–3 rays; a large postorbitallight organ but no suborbital light organ; and the mesocor-acoid is present but unossified or absent (Morrow and Gibbs,1964; Fink, 1985; Harold, 2003). Several species have one ortwo white luminous spots at the upper end of the opercularopening (‘‘shoulder spots’’); a specimen of P. margarita(Scripps Institution of Oceanography SIO 98-5) has addition-al spots on the lateral surface of the body and on the caudalpeduncle. Some species of Photonectes have two lines of whatis referred to as blue luminous tissue along the ventralmidline from the isthmus to the anal-fin origin (Morrow andGibbs, 1964); short transverse branches may be presentbetween each PV photophore, and small patches may occuralong the isthmus, lower jaw, and end of the maxillary(Morrow and Gibbs, 1964). The barbel bulb and postorbitallight organ have been reported to produce light with variouscolors in freshly caught specimens (Beebe and Crane, 1939).Paxton (pers. comm.) noted the barbel bulb in a freshlycaught specimen displayed different colors in incandescentlight than it did in UV light; these color differences have beenpreviously reported by Beebe and Crane (1939).
Of the 22 nominal species described for Photonectes, 12 areconsidered valid and are placed in four subgenera followingMorrow and Gibbs (1964) based on the presence or absenceof black skin covering the dorsal- and anal-fin rays, the
pelvic-fin insertion closer to either the caudal-fin base or thesnout, and the number of IV (IP + OV, isthmus to pelvic fins)photophores (Table 1). The three new species are placed inthe subgenus Photonectes based on the following combina-tion of characters: pectoral fins absent, pelvic fins insertedcloser to the caudal-fin base, dorsal- and anal-fin rays notcovered by black fleshy tissue, and IV photophores 30–39.
Species of Photonectes are distinguished mainly by differ-ences in the barbel structure, presence or absence of extraluminous tissue spots, and presence or absence of blueluminous bands or spots (Morrow and Gibbs, 1964), any ofwhich may be damaged or destroyed during collection. Thisstudy found additional characters useful for identification ofspecies: IP (isthmus) photophore origin (extending the fulllength of the isthmus or beginning posterior to themandibular symphysis after a gap of approximately 50% ofthe isthmus length; Fig. 1B, 1C), gill-filament length(Fig. 2), and tooth length (Fig. 3).
MATERIALS AND METHODS
Measurements were made with vernier calipers to thenearest 0.1 mm and include: standard length (SL), headlength (HL), barbel length, and lengths from snout to pelvicfin (Sn–V), from pelvic fin to vent (V–vent), and from ventto base of caudal fin (vent–C). Percent of SL (% SL) was alsocalculated and is given in Table 2. Due to the limitednumber of specimens, standard deviations were not calcu-lated and, by SIO Collection policy, dissections were notmade for sex determination. Meristic data include fin rays,teeth, and lateral and ventral photophores. Tooth counts arereported as premaxillary, maxillary, mandibular, vomerine,palatine, and basibranchial; maxillary teeth are divided into‘‘erect’’ (anterior canines) and ‘‘oblique’’ (posterior series ofvery small inclined teeth). Photophore terminology (Fig. 1)follows Morrow and Gibbs (1964). Institutional abbrevia-tions are as listed at http://www.asih.org/node/204.
Gill-filament length on first branchial arch (Table 1) isdefined as ‘‘reduced’’ (less than one-half arch depth;Fig. 2A), ‘‘normal’’ (longer than arch depth but notextending beyond opercular opening; Fig. 2B), or ‘‘very
1 Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0208; E-mail:[email protected].
Submitted: 7 October 2009. Accepted: 22 November 2010. Associate Editor: W. L. Smith.F 2011 by the American Society of Ichthyologists and Herpetologists DOI: 10.1643/CG-10-184
Copeia 2011, No. 2, 201–210
long’’ (much greater than depth of arch and extendingbeyond opercular opening; Fig. 2C). Most specimens werecollected by Isaacs-Kidd midwater trawl (IKMT). Onespecimen, SIO 72-17, was collected by an IKMT modifiedto collect plankton (IKPT; Williamson and McGowan, 2009),SIO 77-195 was collected by a neuston net, and SIO 77-200was collected by a dredge box. Collection depths are given inmeters (m), fathoms (fm), or meters-wire-out (mwo).
Photonectes coffea, new species
Figures 3A, 4–6; Tables 1, 2
Holotype.—SIO 73-168, 149.0 mm SL, central equatorialPacific Ocean, 0u01.49S–05.19N, 154u58.7–155u00.19W, R/V
Paratypes.—SIO 73-168, 113.2 mm SL, captured withholotype; SIO 77-195, 37.0 mm SL, 7u329S, 168u299W,neuston net, surface, 14 November 1972; LACM 56904-1(ex SIO 77-167), 112.8 mm SL, 17u40–48.49N, 119u55.4–55.59E, 10-ft IKMT, 0–3000 mwo, 2 August 1976.
Non-type material.—SIO 77-200, 146.6 mm SL, 30u389N,164u24.49W, R/V Sea Scope, dredge box, 3000 fm, 6 July 1972.
Diagnosis.—A member of the subgenus Photonectes based onthe following combination of characters: dorsal- and anal-fin rays not covered with black fleshy skin; pectoral finsabsent; pelvic fins inserted closer to the caudal-fin base; IVphotophores 37–39; and IP photophores begin halfwayposteriorly on the isthmus. Within the subgenus, Photo-nectes coffea differs from P. achirus, P. caerulescens, and P.
Table 1. Selected Meristic and Morphological Characters of Subgenera and Species of Photonectes.
Subgenus/species
Fin-ray countsD&Askin
V fininsertion
Photophore countsGill
filaments
Luminous tissue
D A P IP, gap VAV VAL IV Blue White
Melanonectes
braueri 15–18 17–21 2 no caudal 7–8+2–3, gap 14–15 12–14 30–33 reduced no nonedinema 15–18 18–21 2–3 no caudal 7–8+2, gap 14–18 14–17 28–33 very long no 1, snoutleucospilus 16 18–20 2–3 no caudal 8+2, gap 14–15 12–14 33–34 reduced no 1, snout
Trachinostomias
margarita 15–19 18–24 0–1 yes caudal 8–11, no gap 11–13 11–14 41–45 normal no shoulder, bodymunificus 19 21 0 yes caudal 8, (?) 12 2–4 49–50 (?) normal no noneparvimanus 17–19 21–24 2 yes caudal 10–11, no gap 12–14 12–14 43–49 normal no (?)
Dolichostomias
gracilis 18–22 21–23 0 no snout 8–9, gap 14–15 13 30–32 normal yes none
Photonectes
achirus 15–17 18–19 0 no caudal 8+4, gap 12–13 11–12 31–34 very long yes 1–2, shoulderalbipennis 13–15 15–17 0 no caudal 8+4, gap 13–15 12–14 37–38 normal no 2, shoulderbarnetti n. sp. 13–15 15–16 0 no caudal 7–8, gap 13–15 12–15 38–39 reduced no 1–2, shouldercaerulescens 17–19 18–21 0 no caudal 8+2–3, gap 11–12 11–12 32–34 very long yes nonecoffea n. sp. 12–13 15–17 0 no caudal 8, gap 12–13 13–14 37–39 very long no 1, shouldercorynodes n. sp. 15 16 0 no caudal 7, gap 12 11 34 normal no nonemirabilis 16–17 19–20 0 no caudal 8+1–2, gap 11–12 10–12 33–34 reduced yes nonephyllopogon 20–23 22–25 0 no caudal 8, gap 11–12 12–13 30–31 reduced no none
Sources: Regan and Trewavas, 1930; Morrow and Gibbs, 1964; Gibbs, 1968; material examined.
Fig. 1. (A) Photophore notation: PV–ventrally, from pectoral-fin base topelvic-fin base; IV–IP plus PV; VAV–ventrally, from pelvic-fin base toanal-fin origin; AC–from anal-fin origin to caudal-fin base; OV–laterally,from pectoral-fin origin to pelvic-fin origin; VAL–laterally, from pelvic-finorigin to anal-fin origin or slightly beyond; (B) and (C) IP–along isthmusto pectoral-fin base with insertion at mandibular symphysis orposteriorly halfway along isthmus length, respectively.
Fig. 2. Gill-filament lengths on first branchial arch: (A) reduced, or lessthan one-half branchial arch depth; (B) normal, or longer than one-halfbranchial arch depth but not extending beyond opercular cover; and (C)very long, or longer than branchial arch depth and extending beyondopercular cover.
202 Copeia 2011, No. 2
mirabilis by blue luminous tissue absent (vs. present); differsfrom P. phyllopogon by dorsal-fin rays 12–13 (vs. 20–23) andIV photophores 38–39 (vs. 30–31); differs from P. corynodesby an elongate barbel with filamentous terminal barbel (vs.short barbel with bifid terminal barbel) and one whiteluminous shoulder spot (vs. none); differs from P. barnettiand P. albipennis by barbel with two bulbs (vs. one) and gill-filament length on first branchial arch very long, extendingbeyond opercular opening (vs. reduced or normal, notextending beyond opercular opening).
Description.—Meristics and morphometrics given in Tables 1and 2. Body elongate, 37.0–149.0 mm SL. HL 12.2–14.2 mm(8.3–11.7% SL); Sn–V 64.1–87.1 mm (55.3–58.4% SL); V–vent 22.3–31.5 mm (19.8–21.1% SL); vent–C 25.4–31.0 mm(20.4–23.4% SL). Gill filaments extremely long, extendingbeyond gill openings. Color of body in alcohol fading todark brown-black.
Dorsal-fin rays 12–13; anal-fin rays 15–17; pelvic-fin rays7; pectoral fins absent. Dorsal and anal fins not covered withblack fleshy skin. Pelvic fins inserted closer to caudal finthan to snout; length of longest ray unknown as tips broken.Caudal fin forked, ventral lobe longer than dorsal lobe.
Photophores: IV 37–39 (IP 8 + PV 29–31); VAV 12–13; AC9–12; BR 6–7; OA 37–39 (OV 24–26 + VAL 13–14), last one ortwo photophores over anal-fin base; IP series with gap,begins posteriorly about halfway along isthmus length(Fig. 1C). Secondary photophores on head and cheeks, andalong dorsal- and anal-fin rays; on body extend in irregularlines from dorsal midline to each OV photophore, occur insmall clusters below each OA and PV, and in two narrowlines along the body above PV series (Fig. 4). Postorbitalphotophore teardrop-shaped, approximately equal in lengthto eye diameter. One white luminous shoulder spot. No blueluminous tissue.
Premaxillary teeth 8–11; maxillary teeth 6–13 erect and 8–13 oblique; mandibular teeth 29–35; vomerine teeth 2–3pairs, lateral teeth longest; palatine teeth 2–4 pairs, first andthird pairs longest; basibranchial teeth absent or 6 pairs(when present, a gap after the first three pairs (3 pairs, gap, 3pairs), with posterior tooth in third and sixth pairs longest).Upper and lower jaw teeth very short, no long caninespresent (Figs. 5A, 7).
Barbel elongate, 11.2–16.9 mm (9.9–11.7% SL), stempigmented, without secondary photophores and with twolarge ovoid bulbs; proximal organ at about one-quarterdistance from base of dorsal side of stem; distal bulb flat onposterior side and on anterior side a V-shaped line of darktissue extending distally along length of bulb giving bulb aresemblance to a coffee bean; dark tissue continues distallyon posterior side of bulb onto long whip-like filamentoustip.
Distribution.—Known from the central equatorial and thecentral North Pacific and from the western Pacific nearLuzon Island, Philippines (Fig. 6).
Etymology.—The specific name refers to the shape of theterminal barbel bulb which resembles a coffee bean.
Photonectes barnetti, new species
Figures 3B, 6–8; Tables 1, 2
Holotype.—SIO 71-296, 41.6 mm, central North Pacific,27u25.5–28.59N, 155u26.3–27.39W, R/V Thomas Washington,IKMT, 0–1500 mwo, 29 September 1971.
Paratypes.—SIO 71-296, 25.4 mm SL, captured with theholotype; USNM 395048 (ex SIO 71-297), 23.4 mm SL,27u23.4–25.19N, 155u10.6–27.29W, IKMT, 0–3000 mwo, 29September 1971; LACM 57213-1 (ex SIO 71-305), 22.3 mmSL, 27u25.6–25.89N, 155u30.9–33.59W, IKMT, 0–1500 mwo, 1October 1971.
Non-type material.—SIO 71-310, 23.4 mm SL, 27u27.0–28.29N, 155u28.6–47.09W, IKMT, 0–3000 mwo, 2 October1971; SIO 72-9, 23.4 mm SL, central North Pacific, 27u21.6–24.09N, 155u24.4–26.69W, IKMT, 0–3000 mwo, 23 Septem-ber 1971; SIO 72-17, 20.6 mm SL, 27u21.5–21.69N, 155u22.4–23.99W, IKPT, 0–1000 mwo, 27 September 1971.
Diagnosis.—A member of the subgenus Photonectes based onthe following combination of characters: dorsal- and anal-fin rays not covered with black fleshy skin; pectoral finsabsent; pelvic fins inserted closer to the caudal-fin base; IVphotophores 38–39; and IP photophores begin halfwayposteriorly on the isthmus. Within the subgenus, P. barnetti
Fig. 3. Schematic of left lateral view of tooth patterns with upper andlower jaws shown disarticulated. Arrows indicate junctures of premax-illary and maxillary bones. (A) P. coffea, new species, holotype, SIO 73-168, 149.0 mm; (B) P. barnetti, new species, holotype, SIO71-296,41.6 mm; (C) P. corynodes, new species, holotype, SIO 73-170,24.1 mm.
Klepadlo—New species of Pacific Photonectes 203
differs from P. achirus, P. caerulescens, P. coffea, and P.corynodes by gill-filament length on first branchial archreduced (vs. normal or very long); differs from P. phyllopogonby dorsal-fin rays 13–15 (vs. 20–23) and IV photophores 38–39 (vs. 30–31); differs from P. mirabilis by blue luminoustissue absent (vs. present) and barbel with elongate stem andwhiplike filament (vs. short stem and bifid filament).
Description.—Meristics and morphometrics given in Tables 1and 2. Small-sized fish with elongate body, 20.6–41.6 mmSL. HL 2.5–6.1 mm (10.7–14.9% SL); Sn–V 12.2–25.4 mm(59.2–64.9% SL); V–vent 2.1–7.1 mm (9.0–17.1% SL); vent–C3.8–8.1 mm (16.2–23.3% SL). Gill filaments extremely shorton first gill arch, increasing in length on each succeedingarch, but not extending beyond gill cover. Body color inalcohol rusty-brown; probably blackish in life.
Dorsal-fin rays 13–15; anal-fin rays 15–16; pelvic-fin rays7; pectoral fins absent. Dorsal and anal fins not covered withblack fleshy skin; rays outlined with small white luminoustissue spots. Longest pelvic-fin ray extends at least to vent;pelvic fins insert closer to caudal fin than to snout. Caudalfin forked and elongate; ventral lobe longer than dorsallobe.
Photophores: IV 38–39 (IP 7–8 + PV 30–31); VAV 13–15;AC 8–12; BR 6–7; OA 39–42 (OV 26–27 + VAL 12–15), lasttwo or three photophores over anal-fin base; IP series withgap, begins posteriorly about halfway along isthmus length
(Fig. 1C). Secondary photophores on body similar in patternand occurrence to P. coffea. Postorbital photophore ovoid,length approximately equal to eye diameter. One or twowhite luminous shoulder patches. No blue luminous tissue.Small patches of white luminous tissue outline dorsal- andanal-fin rays.
Premaxillary teeth 6–12, first two teeth smallest followedby longer canines; maxillary teeth 3–6 erect and 6–10oblique; mandibular teeth 17–26; vomerine teeth 1–2 pairs,lateral tooth longest; palatine teeth 1–2 pairs; basibranchialteeth 2–3 pairs, small gap between first and second pairs.Jaws with needle-like canines; 3–5 smaller teeth betweeneach longer canine (Fig. 3B).
Barbel elongate, 2.0–4.1 mm (8.6–13.4% SL); stem withoutdiscernible secondary light organs; proximal and distalthirds of stem pigmented, middle third pale (‘‘white,’’unknown if luminous or reflective); barbel ends in a largeovoid bulb, with V-shaped wedge of pigmented tissue onanterior side extending in a thin line across bulb and endingat the base of a pale elongate terminal filament; bulbencased in a clear sheath.
Distribution.—North Pacific Gyre, approximately 27uN,155uW (Fig. 6).
Etymology.—Named in honor of the late Michael Barnett,who collected and recognized the new species.
Table 2. Meristics and Morphometrics of the Pacific Ocean New Species of Photonectes. Values for holotypes; range for all known specimens givenfor P. coffea and P. barnetti.
P. coffea (n = 5) P. barnetti (n = 7) P. corynodes (n = 1)
Mandibular 32 (29–35) 26 (17–26) 16Vomerine 3 (2–3) pr. 2 (1–2) pr. 1 pr.Palatine 4 (2–4) pr. 1 pr. 1 pr.Basibranchial 6 (0–6) pr. 3 (2–3) pr. 1 + 1–2 pr.
Holotype.—SIO 73-170, 24.1 mm SL, central equatorialPacific, 0u03.89S–0u07.09N, 154u54.5–56.09W, R/V Melville,10-ft IKMT, depth approx. 1280 m, 17 July 1972.
Diagnosis.—A member of the subgenus Photonectes based onthe following combination of characters: dorsal- and anal-fin rays not covered with black fleshy skin; pectoral finsabsent; pelvic fins inserted closer to the caudal-fin base; IVphotophores 34; and IP photophores begin halfwayposteriorly on the isthmus. Differs from all other speciesin the subgenus except Photonectes mirabilis by a barbelwith a small side-branch on the terminal filament. Differsfrom P. mirabilis in gill filaments ‘‘normal’’ (vs. veryreduced); jaw teeth variable length (vs. short) canines; 16
anal-fin rays (vs. 19–20); no blue luminous tissue (vs.present); and no light organs inside the lower jaw (vs. threepairs).
Description.—Meristics and morphometrics given in Tables 1and 2. Small, elongate specimen, 24.1 mm SL. HL 3.8 mm(15.8% SL); Sn–V 15.5 mm (64.3% SL); V–vent 3.5 mm(14.5% SL); vent–C 5.2 mm (21.6% SL). Gill filaments extendjust to edge of gill cover; tips of filaments dark. Color ofbody in preservative faded to light rust-brown; probablyblack in life.
Dorsal-fin rays 15; anal-fin rays 16; pelvic-fin rays 7;pectoral fins absent. No black fleshy tissue over dorsal- andanal-fin rays. Pelvic fins inserted closer to caudal fin than tosnout; pelvic-fin rays extend at least to vent. Caudal finforked, ventral lobe longer than dorsal lobe.
Photophores: IV 34 (IP 8 + PV 26); VAV 12, last twophotophores over anal-fin origin; AC 11; OA 33 (OV 22 +
Fig. 4. Left lateral view of Photonectes coffea, new species, holotype, SIO 73-168, 149.0 mm.
Klepadlo—New species of Pacific Photonectes 205
VAL 11); BR 7; IP series with gap, begins about midway onthe isthmus (Fig. 1C). Small secondary photophores presenton head body, in vertical lines from mid-dorsal to each VAV,and along dorsal- and anal-fin rays. Postorbital photophorelength 0.5 mm, about equal to eye diameter. No blueluminous tissue or white luminous shoulder spots.
Premaxillary teeth 4; maxillary teeth 6 erect and 7 oblique;mandibular teeth 16; vomerine teeth 1 pair; palatines eachwith a single tooth; basibranchial teeth 2–3 widely separatedpairs (one pair followed by a gap and then 1–2 pairs). Jawteeth composed of long and short canines (Fig. 3C).
Barbel short, 4.5 mm (18.7% SL); stem of barbel short,,0.5 mm (,14% of barbel length), and black-pigmented,followed by a large white bulb, about twice as long as wideand with an hourglass shape, with a narrow (about 12.5% ofbulb width) bifid black filament distally; shorter branchends in a luminous bulb tipped with a small tuft of filamentsand longer branch ends in a mace- or club-shaped luminousbulb. All three bulbs surrounded by a thin transparentsheath. No secondary photophores along stem.
Distribution.—The only known specimen, the holotype, wascaptured in the equatorial eastern Pacific (Fig. 6).
Etymology.—From the Greek koryne, meaning mace or club,referring to the appearance of the terminal bulb.
DISCUSSION
Specimens of Photonectes are often difficult to identify tospecies. Large adults may have rather deep flaccid bodiessubject to damage during collection, losing barbels, ventro-lateral photophores, and luminous tissue. Barbels mayundergo ontogenetic changes (e.g., P. parvimanus and P.fimbria; Beebe and Crane, 1939; Morrow and Gibbs, 1964).The additional characters found during this study (gill-filament length, gap/no gap before the IP series, and overalltooth length) increase the combination of available charac-ters used for identification.
Within the subgenus Photonectes, P. coffea, P. barnetti, andP. albipennis share a high IV photophore count (37–39), oneor two white luminous shoulder spots, absence of blueluminous tissue, and an elongate barbel with a singleterminal filament. Photonectes barnetti differs from P. coffeaand P. albipennis by having a barbel with a single large ovoidbulb, one or two pairs of palatine teeth (vs. 2–4 pairs), bothjaws with variable-length (vs. short length) canines, and gillfilaments very reduced on the first branchial arch. Photo-nectes coffea differs from P. albipennis in having a shorterbarbel (,12% SL vs. .20% SL) with two large bulbs (vs. oneminute bulb), and very long gill filaments extending beyondthe opercular opening (vs. not extending beyond theopening).
The barbel of P. corynodes is most similar to the barbel of P.mirabilis (Parr, 1927:figs. 59–60) in having a side branchalong the terminal filament. It differs in the absence of blueluminous tissue, fewer anal-fin rays (16 vs. 19–20), ‘‘normal’’gill filaments on the first branchial arch (vs. very reduced),no light organs inside the lower jaw, a single pair of teetheach on the vomer and the palatines (vs. two pairs each),and both long and short canines in both jaws (vs. short evencanines in both jaws).
The length of the gill filaments on the first branchial archis variable within the genus and within the subgenusPhotonectes (Table 1; Fig. 2) and is probably related to theoxygen content of the water mass where the species occur.The extremely long gill filaments of P. achirus, P. caerules-cens, and P. coffea suggest low-oxygen habitats and havebeen reported in other deep-sea fishes such as Cyclothone(DeWitt, 1972) and Scopelarchoides nicholsi (Johnson, 1974).The gill filaments of reduced length in P. barnetti, P.mirabilis, and P. phyllopogon suggest a relatively well-oxygenated water as indicated for some species of Platy-troctidae (Matsui and Rosenblatt, 1987:12). Data on theoxygen content were not checked for this paper but areavailable in cruise reports on file at the Scripps Institution ofOceanography.
The absence of the gap between the mandibular symphy-sis and the origin of the IP photophores appears to beunique to the subgenus Trachinostomias (Table 1; Fig. 1B,1C). While not present in the subgenus Photonectes, thischaracter adds to the definition of the subgenera and willaid in the future identification of species of Photonectes.
Sexual dimorphism of the postorbital organ (PO) has beennoted in many stomiid fishes (Krueger and Gibbs, 1966;Gibbs, 1969; Clarke, 1998, 1999; Sutton and Hartel, 2004;Kenaley, 2007; Borodulina, 2009), including some species ofPhotonectes (cited in Herring, 2007:table 3). However,following curatorial policy at SIO, dissections for sex
Fig. 5. Left lateral view of barbel, Photonectes coffea, new species,holotype, SIO 73-168, 149.0 mm, with anterior view of terminal bulb.
206 Copeia 2011, No. 2
determination were not done. The size of the PO organswithin a species were not noticeably different. Availability ofmore specimens may show otherwise.
5a. Dorsal-fin rays 15; anal-fin rays 16; barbel with anhourglass-shaped bulb and a bifid terminal fila-
Fig. 6. Distribution of Photonectes coffea (closed circle), P. barnetti (closed square), P. corynodes (closed triangle). Symbols may represent morethan one record.
Klepadlo—New species of Pacific Photonectes 207
ment, each branch ending in a small bulb; gillfilaments on first branchial arch ‘‘normal’’(Fig. 2B), length about equal to arch depth _ _ _ _ _ _ _ _ _ _
with round bulb bearing a terminal appendageending in a translucent leaf-like expansion withserrated edges and four terminal filaments; gillfilaments on first branchial arch reduced (Fig. 2A),length about half arch depth _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ P. phyllopogon
6b. Barbel with a distal bean-shaped bulb and aproximal bulb; length of gill filaments on firstbranchial arch very long, extend beyond opercularopening _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ P. coffea, new species
7a. Length of gill filaments on first branchial arch verylong, twice depth of first arch depth; dorsal-fin rays12–13; barbel with single minute bulb and a stementirely pigmented; premaxillary and maxillaryteeth all short canines _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ P. albipennis
7b. Length of gill filaments on first branchial archshort, #0.53 arch depth; dorsal-fin rays 14–15;barbel with one large ovoid distal bulb and anunpigmented area about midlength; premaxillaryand maxillary teeth a combination of long andshort canines _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ P. barnetti, new species
R. Rosenblatt, P. Hastings, and H. J. Walker, Jr. providedhelpful critiques of the manuscript, and encouragement andsupport of this project. Curatorial assistance was provided byH. J. Walker (SIO), R. Feeney (LACM), and J. Williams and S.Smith (USNM). Photographs by M. Soave and C. Sheridy(UCSD-SIO).
LITERATURE CITED
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Fig. 8. Left lateral view of barbel, Photonectes barnetti, new species,holotype, SIO71-296, 41.6 mm.
Klepadlo—New species of Pacific Photonectes 209
Matsui, T., and R. H. Rosenblatt. 1987. Review of the deep-sea fish family Platytroctidae (Pisces: Salmoniformes).Bulletin of the Scripps Institution of Oceanography26:1–160.
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Fig. 9. Photonectes corynodes, new species, holotype, SIO 73-170, 24.1 mm.
Fig. 10. Left lateral view of barbel, Photonectes corynodes, newspecies, holotype, SIO 73-170, 24.1 mm.
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