Photonectes waitti, Flynn & Klepadlo, 2012

Flynn, A. J. & Klepadlo, C., 2012, Two new species of Photonectes (Teleostei: Stomiidae) from the Indo-Pacific, and a re-examination of P. achirus, Memoirs of Museum Victoria 69, pp. 259-267 : 260-261

Photonectes waitti new species

Figures 2a,b , 5 ; Table 1

Holotype: NMV A 30913-001 (71.4 mm SL), 0°34.836'—35.329'N, 176°56.432'—49.956'W, neuston net, 0—0.5 m depth, R / V Seward Johnson, Catalyst II expedition, 06 March 2009, 14:04—15:05.

Paratypes: AMS I.49494-010 (48.7 mm SL), 16°34.25'S, 147°08.01'E, 11 December 2010, 19:43—20:43, RMT8 trawl, 330 m depth ; NMV A 30908-001 /-002 (2: 22.5—32.6 mm SL), 0°21.243'- 21.257'N, 176°50.117'-49.575'W, 23 February 2009, 12:17—13:17, neuston, 0—0.5 m depth ; NMV A 30915-001 (1: 32.1 mm SL) and SIO 11-301 /-302 (2: both 48.5 mm SL), 0°27.568'—27.658'N, 176°51.848'— 50.574'W, 28 February 2009, 12:32—13:32, neuston, 0—0.5 m depth ; NMV A 30906-001 /-002/-003/-004/-005 (5: 31.6—51.0 mm SL), collected with holotype ; NMV A 30908-001 /-002 (2: 22.5—32.6 mm SL), 0°21.243'—21.257'N, 176°50.117'—49.575'W, 23 February 2009, 12:17—13:17, neuston, 0—0.5 m depth ; NMV A 30907-001 /-002/- 003/-004 (4: 25.2—30.7 mm SL), 0°54.289'N, 177°09.476'W, 02 May 2009, neuston net, 0—0.5 m depth ; SIO 11-300 (37.6 mm SL), 0°13.518'—13.212'N, 176°46.428'—45.634'W, 19 February 2009, 07:43—08:43, neuston, 0—0.5 m depth ; SIO 11-303 (2: 25.4—41.5 mm SL), 0°53.000'—50.586'N, 176°57.332'—56.657'W, 20 March 2009, 12:59—13:57, neuston net, 0—0.5 m depth ; USNM 402774 (32.3 mm SL), 01°19.045'—18.335'N, 176°47.913'—47.673'W, 19 April 2009 , RMT trawl M205, 1200 m depth ; USNM 300149 (23.4 mm SL), 12°40'N, 51°13'E, 1 m plankton net, captured at surface, R / V Anton Bruun Cr. 5, sta. 287A, IIOE Expedition, 3 February 1964 ; USNM 300199 (26 mm SL), 21°20'—30'N, 158°20'—30'W, 26 September 1973, 3 m IKMT, 0—110 m depth , T. Clarke 73-9-33; USNM 300201 (24.8 mm SL), 21°20'—30'N, 158°20'—30'W, 30 August 1973, 03:18— 05:15, 3 m IKMT 0—350 m depth , T. Clarke 73-8-31.

Diagnosis: Differs from other species in the subgenus Photonectes in the following combination of characters: dorsal-fin rays 11—14, anal-fin rays 12—16; IV photophores 38—39, PV photophores 24—25; absence of blue luminous tissue; length of gill filaments on first branchial arch reduced, less than depth of gill arch; and barbel with two large bulbs in series. Few species of Photonectes have more than one large bulb or luminous area on the barbel (secondary photophores excluded). Above the main bulb in P. mirabilis are small bulbs on the stem and a tiny terminal bulb. P. phyllopogon has a single bulb and a terminal luminous appendage ( Morrow and Gibbs, 1964). P. barnetti has a large pale area along the stem below the bulb (luminescent colour uncertain) ( Klepadlo, 2011). P. coffea has two bulbs in series without any terminal bulb ( Klepadlo, 2011). For P. waitti there are two large bulbs in series and a tiny bulb at the end of the filament. Photonectes waitti differs from P. mirabilis and P. phyllopogon in having 11—14 dorsal-fin rays (vs. 16—17 and 20—23, respectively), 12—16 anal-fin rays (vs. 19—20 and 22—25, respectively), and 38—39 IV photophores (vs. 33—34 and 30—31, respectively). It differs from P. coffea in having gill filaments on first gill arch reduced (vs. very long, extending beyond gill opening), and PV photophores 24—25 (vs. 29—31). It differs from P. achirus , P. caerulescens , and P. mirabilis in lacking blue luminous tissue.

Description: Body elongate, 20.9—71.4 mm SL; depth about eight times into length. HL 3.2—8.7 mm (11.0—18.1% SL, mean 15.3%); Sn-V 13.3—47.9 mm (58.5—67.4% SL, mean 62.1%); V-vent 3.4—10.5 mm (13.9—21.4% SL, mean 18.2%); vent-C 4.3—13.0 mm (15.6—23.4% SL, mean 19.9%) (see Table 1 ). Eye 0.8—1.9 mm (17.2—29.3% HL, mean 23.5%). Opercle concave dorsally and lobate posteriorly. Gill filaments on first branchial arch reduced, length less than arch depth; tips of filaments dark. Color of body in life dark brown to black. On fresh specimens or undamaged preserved specimens, narrow black lateral bands in line with PV, VAV and AC photophores. On freshly caught specimens, these lateral bands could be seen to harbor minute secondary photophores and luminous patches (described further below).

Dorsal-fin rays 12 (11—14, rarely 15—16); anal-fin rays 14 (12—16, rarely 17—19); pelvic-fin rays 7 (rarely 6); pectoral fins absent. Dorsal and anal fins not covered with black fleshy skin. Pelvic fins inserted closer to caudal fin than to snout (33.1—42.4% SL vs. 58.6—67.4% SL); longest ray extending at least to anus (tips broken). Caudal fin forked and elongate; ventral lobe longer than dorsal lobe. All fin-rays covered with melanophores extending halfway along the length; membranes clear.

Photophores: IV 38—39, rarely 35—37 ( IP 12, rarely 11 or 13; PV 24—25, rarely 22, 23 or 26); VAV 13—14, rarely 12 or 15; AC 11—12, rarely 13; OA 38—39, rarely 35—37 ( OV 24—26, rarely 23; VAL 12—13, rarely 14—15), last 1 to 2 photophores over anal-fin base; BR-7, rarely 6. IP series beginning about halfway along isthmus length, approximately opposite BR-7; space between IP-8 and IP-9 about twice space between IP-1 and IP-2 making series 8 + 4. Anterior end of AC series raised, approximately even with last VAL photophore, tapering downward over anal fin base and ending along ventro-lateral caudal peduncle. Secondary photophores on head and body, mainly concentrated in vertical lines from dorsum to each PV, VAV and AC photophore; also between IV and OA series and along ventrum in rather horizontal lines; no secondary photophores on any fin-ray. Postorbital organ ovoid, 0.7—0.9 mm (12.3—18.8% HL, mean = 14.6%; skin flap over posterior end in NMV A.30907-003. One ovoid PRO photophore; one smaller circular SO photophore. SO photophore directed ventrally and placed in a cup-like structure. PRO and SO photophores of fresh specimens reddish pink under visible light. Blue luminous tissue and dark markings absent.

Teeth caniniform, long and short; premaxillary teeth longest, needle-like. Premaxillary teeth 5—8; 4—8 maxillary teeth erect and 4—10 oblique; mandibular teeth 11—25; vomerine teeth in 2 to 3 pairs, lateral teeth longest; palatine teeth in 2 pairs, about equal length; basibranchial teeth in 2 to 4 pairs (anterior and posterior pairs separated by gap, 1 to 2 pairs followed by 1 to 2 pairs; posterior tooth in each group longest).

Barbel shorter than head, 2.3-5.5 mm (59.0—85.4% HL, mean 74.0%), with two main bulbs and a fine terminal filament. One specimen ( SIO 11-304 ) with very tiny bulb at distal end of terminal filament. Stem pigmented, no secondary photophores; first segment (~45% of barbel length) tapering into first bulb with pigment cup-like around bulb base. First bulb ovoid (~18% of barbel length), width about three times stem width, tapering into short segment of stem (~9% of barbel length) followed by second bulb. Section of stem between bulbs with melanophores increasing in concentration distally. Second bulb elongate (~18% of barbel length), narrow, about twice stem width, and with melanophore-line from stem extending length of bulb onto short terminal filament (~9% of barbel length). In freshly-caught specimens bulbs lavender to pink under white light.

Distribution: Known from tropical western and central Pacific Ocean, northwestern Coral Sea and Indian Ocean (Gulf of Aden) at depths of 0—1200 m.

Etymology: Named in recognition of Theodore (Ted) Waitt, the founder of the Waitt Family Foundation and the Waitt Institute. The Waitt Institute sponsored and directed the expedition of the R / V Seward Johnson to the equatorial western Pacific Ocean (Catalyst II expedition) during which this species was collected. Remarks: Photonectes waitti is a widespread tropical openocean species. Twenty-one specimens were collected in 2009 from the equatorial western Pacific Ocean. One specimen was collected in 2010 from Australian waters in the Coral Sea. While examining older (40+ years) museum specimens labeled Photonectes sp. , three additional specimens were found that extended the distribution of P. waitti into the Central Pacific, in the vicinity of Hawaii, and the northwestern Indian Ocean (Gulf of Aden).

Figures

Figure 2. Photonectes waitti new species a) NMV A.30906-005, 51.0 mm, paratype; b) lateral view of head and barbel, NMV A.30913-001, 71.4 mm, holotype. Photograph by NMV.

Figure 5. Distribution of Photonectes waitti (black square), P. paxtoni (black circle), P. achirus (black triangle; white triangle = literature records). Symbols may represent more than one record