Photonectes sphaerolampas Prokofiev & Klepadlo 2019, new species

Photonectes sphaerolampas new species Figs. 2–4 Photonectes phyllopogon: Parin et al., 1976: 218, figs. 4, 5 (misidentification). Holotype. AMS I.20941-010, 121.0 mm SL, 12° 40.0´S, 144° 01.0´E, 0–120 m depth, 21 February 1979. Paratypes. AMS I.20941-033, 127.5 and 189.0 mm SL, same data as for holotype. IOM 3583, 72.5 mm SL, 0° 01' S, 139° 41' W, 200 m depth, R/V Akademik Kurchatov, cruise 17, sta. 1458, Isaacs-Kidd trawl no. 21, 28 January 1974. Diagnosis. A species of Photonectes based on the following combination of characters: mental barbel with large spherical bulb bearing darkly pigmented terminal appendage splitting at tip into short filaments; solid longitudinal band of blue luminous tissue present along flanks from gill opening to caudal-fin base; a longitudinal row of small roundish spots of blue luminous tissue above IV photophores on each side of body, connecting with row on opposite side by transverse interrupted streaks of blue luminous tissue alternating with anterior 12 PV photophores, and high number of AC photophores (14–18). Description. Body elongate, tapering toward caudal fin (Fig. 2). Snout 1.0–1.2 times shorter than eye. Morphometric values, in % of SL: head length 11.5 (10.3–15.2); snout length 1.6 (1.5–2.8); eye diameter 2.0 (1.6–2.8); least interorbital width 3.8 (3.7–4.1); barbel length 5.1 (3.6–6.8); upper jaw length 13.8 (13.2–17.4); postorbital organ length 2.8 (2.6–3.5); ditto, greatest depth 1.0 (0.9–1.2), entire black surrounding area 4.5 (4.2–5.0); predorsal, preanal and prepelvic distances 77.5 (76.0–77.9), 79.2 (77.9–79.2) and 56.2 (52.9–62.8), respectively; dorsal- and anal-fin base length 14.9 (15.1–17.9) and 16.6 (16.8–19.8), respectively; pelvic-fin length 13.1 (10.1–14.5); greatest body depth 9.3 (7.2–11.7); least depth of caudal peduncle 2.1 (1.9–2.4). Opercle slightly concave dorsally, its posteroventral corner somewhat produced, rounded; gill filaments extending beyond gill cover. Gill filaments of first arch long, of equal length along ceratobranchial-1. Color of skin fading to rusty brown after more than 40 years of storage; areas encircling nares and supraorbital pores blackish. Dorsal-fin rays 20 (16–21); anal-fin rays 20 (18–23); pelvic-fin rays 7; pectoral fins absent. Black fleshy skin extends onto bases of dorsal and anal fins only. Pelvic fins extending to vent. Caudal fin forked, tips of lobes broken, rays 9 + 9. Vertebrae 48. Photophores: IP 10 (9); PV 23 (21–23); IV 33 (31–32); VAV 12 (12–15) [last 3 over anal-fin base]; AC 17 (14–18); IC 62 (57–62); OV 18 (18–21); VAL 15 (13–15) [last 3 over anal-fin base]; OA 33 (33–34); BR 9 (8–9). Anteriormost six IP photophores smaller than remaining ones, closely spaced, with distances between them not exceeding diameter of organ; 7 th IP photophore separated from 6 th one by 1.5 of its diameter and from 8 th one by two diameters; 8 th and 9 th IP photophores closely spaced. Distance between anterior tip of isthmus and first pair of IP photophores equals to half-length of isthmus. Secondary photophores very small, scattered over head and body, most densely clustered along dorsum, between OV and PV organs and between PV organs of neighbouring sides, absent on fin-rays. Postorbital organ moderately large, elongate, tapered posteriad, 1.4 (1.3–1.6) times eye. Antero-ventral corner of jet-black tissue encircling the photogenic gland of postorbital organ extends anteriad to a vertical through the center of eye (Fig. 3A). Blue luminous tissue on body arranged as follows: a solid longitudinal band along flanks from gill opening to caudal-fin base (Fig. 3B); a longitudinal row of small roundish spots above IV photophores on each side of body from 1 st photophore IP to 16 th photophore PV; transverse interrupted streaks alternating with PV photophores, originating from space between last IP and 1 st PV photophores and ending in interspace between 11 th and 12 th photophores of PV (Fig. 3C); diffuse patch of pale blue tissue in posterior portion of each mandibular ramus. Clusters of small, luminous whitish spots behind posterior end of maxillary. No luminous tissue inside mouth. All jaw bones with heterogeneous dentition; premaxillary teeth biserial, teeth in outer row much shorter (Fig. 3D). Premaxillary and dentary of holotype slightly disarticulated; exact number of teeth difficult to count. Paratypes possessing 5–8 + 2–3 caniniform teeth on premaxillaries. Maxillary with 11 (7–13) erect caniniform teeth of different sizes, following by a comb-like row of inclined needle-like teeth (13 (10–19) in number); 3 rd erect maxillary teeth longest, first and last two teeth smallest. Dentary teeth 21–29 in number, unequal in length (Fig. 3E). Vomer with 3 + 3 (2–3 + 2–3) unequal teeth. Each palatine bearing 3 (1–3) teeth. All inner premaxillary teeth, some (anteriormost) teeth on dentary, vomerine and palatine teeth with weakly barbed tips. Barbel moderately short (43.6 (about 35–45) % of head length), with a large spherical bulb bearing a single heavily pigmented terminal appendage with tip branched into four short processes (Figs. 3B, 3F, 4). Length of bulb equal in length to its terminal appendage and about twice as short as length of pigmented stem. Etymology. The name (Greek “σφαίρα” for spherical and “λάµπα” for lantern) reflects the characteristic shape of the bulb of the mental barbel. Comparisons. Photonectes sphaerolampas is similar to P. gracilis in arrangement of blue luminous tissue on body, but differs from this species in the structure of mental barbel (thick pigmented stem lacking bulbs but with thin unpigmented distal appendage terminating by three short filaments in P. gracilis), and in barbel much longer than eye (vs. as short as eye or shorter). Photonectes sphaerolampas resembles P. phyllopogon in structure of mental barbel (both species share large spherical bulb with darkly pigmented terminal appendage). However, in P. phyllopogon this appendage ending with a flattened unpigmented (apparently luminous) extension with irregularly indented distal margin (Fig. 5). Furthermore, the new species differs from P. phyllopogon in presence of blue luminous tissue on body and anteroventral extension of jet-black tissue encircling postorbital photogenic gland (both absent in P. phyllopogon), in the uniformly long gill filaments on first ceratobranchial (vs. reduced in upper part in P. phyllopogon), and in the higher count of AC photophores (14–18 vs. 12). Distribution. Equatorial Western and Central Pacific.Published as part of Prokofiev, Artem M. & Klepadlo, Cynthia, 2019, Two new species of Photonectes with blue luminous tissue on body, and a re-examination of P. mirabilis (Teleostei: Stomiidae), pp. 270-282 in Zootaxa 4590 (2) on pages 273-276, DOI: 10.11646/zootaxa.4590.2.4, http://zenodo.org/record/265199

Two new species of Photonectes with blue luminous tissue on body, and a re-examination of P. mirabilis (Teleostei: Stomiidae)

Prokofiev, Artem M., Klepadlo, Cynthia (2019): Two new species of Photonectes with blue luminous tissue on body, and a re-examination of P. mirabilis (Teleostei: Stomiidae). Zootaxa 4590 (2): 270-282, DOI: 10.11646/zootaxa.4590.2.

Photonectes cyanogrammicus Prokofiev & Klepadlo 2019, new species

Photonectes cyanogrammicus new species Fig. 1 Holotype. MNHN 2002-3685, 140 mm SL, 9° 10' 4.8'' S, 159° 52' 58.8'' E, 749–799 m, R/ V Alis, camp. Salomon 1, sta. cp1751, 25 September 2001. Diagnosis. A species of Photonectes based on the following combination of unique derived characters: mental barbel distally expanded, lacking bulbs or appendages but with distal portion unpigmented and apparently luminous, and two posteriormost photophores VAV distinctly raised (vs. all photophores VAV on the same level in other Photonectes spp.). Description. Body elongate, tapering toward caudal fin (Fig. 1A). Snout 1.6 times shorter than eye. Morphometric values, in % of SL: head length 13.6; snout length 1.8; eye diameter 2.8; least interorbital width 3.9; barbel length 5.3; upper jaw length 13.6; postorbital organ length 3.9; ditto, greatest depth 0.9, entire black surrounding area 4.6; predorsal, preanal and prepelvic distances 76.4, 76.4 and 60.7, respectively; dorsal- and analfin base length each 18.9; pelvic-fin length 14.0; greatest body depth 11.4; least depth of caudal peduncle 2.1. Opercle slightly concave dorsally, its posteroventral corner somewhat produced; gill filaments extending slightly beyond gill cover. Gill filaments in upper half of first ceratobranchial moderately shortened (1.5 times shorter than filaments of lower half). Color of skin uniformly black. Dorsal-fin rays 21; anal-fin rays 23; pelvic-fin rays 7; pectoral fins absent. Black fleshy skin extends on basal 1/3 of dorsal and anal fins. Pelvic fins reaching slightly before vent. Caudal fin forked, with lower lobe longer. Vertebrae 53. Photophores: IP 9; PV 22; IV 31; VAV 16 [last 5 over anal-fin base, last 2 raised]; AC 9; IC 56; OV 22; VAL 12 [last 2 over anal-fin base]; OA 34; BR 10. Anteriormost six IP photophores smaller than remaining ones, closely spaced, with distances between them not exceeding diameter of organ; remaining three IP photophores well-separated from each other [distance between 6 th and 7 th photophores and 8 th and 9 th photophores equal to two diameters of organ; distance between 7 th and 8 th photophores equal to 1.5 diameter of organ]. Distance between anterior tip of isthmus and first pair of IP photophores about 3 times greater than combined length of anteriormost six IP photophores (66.7% of isthmus length). Secondary photophores very small, scattered over head and body, most densely clustered on cheeks, along dorsum, between OV and PV organs and between PV organs of neighbouring sides, absent on fin-rays. Postorbital organ large, elongate, tapered posteriad, 1.4 times eye diameter. Antero-ventral corner of jet-black tissue encircling the photogenic gland of postorbital organ extends anteriad to a vertical through the center of eye (Fig. 1B). Blue luminous tissue on lower sides of body arranged as follows: a longitudinal line on each side, 1.5 times closer to PV than to OV organs, consisting of interrupted streaks between isthmus and anal-fin origin, conspicuous up to 18 th photophore PV, less obvious behind; transverse interrupted streaks connecting longitudinal lines of left and right sides of body between photophores, originating from space between 6 th and 7 th organs of IP and discernible until 10 th photophore of VAV, alternating with photo phores (Fig. 1C). Diffuse indistinct superficial band of blue luminous tissue originating somewhat behind a level of pelvic-fin origin, extending toward caudal-fin base, having wavy extensions downward forming reticulate appearance in anterior portion (up to a level of mid-base of anal fin: Fig. 1D). Small spots of white luminous tissue scattered along anal-fin base. Clusters of small pale bluish to whitish luminous spots on opercle and behind posterior end of maxillary; no luminous tissue inside mouth. Jaw dentition heterogeneous; premaxillary teeth biserial, teeth in outer row much shorter (Figs. 1E, 1F). Premaxillary with 9 + 3 caniniform teeth on left side and 8 + 4 teeth on right side, their tips barbed. Inner premaxillary teeth distinctly longer than those on maxillary and dentary. Maxillary with 11/12 erect caniniform teeth, following by a comb-like row of inclined needle-like teeth (13 in number); erect maxillary teeth increasing in size from 1 st to 5 th, becoming smaller backward. Dentary teeth 30/32, consisting of long and short canines (Fig. 1E). Vomer with 3 + 3 teeth, gradually increasing in size from first to third, third tooth very long, extending behind 2 nd palatal tooth. Palatine with 2 teeth on each side, second longest. Barbel rather short (39% of head length), lacking a conspicuous bulb or any appendages, but unpigmented and apparently luminous in distal portion (60% of full barbel length); no sharp boundary between darkly pigmented stem and unpigmented distal portion (Fig. 1G). Etymology. The name (Greek “κυανό” for blue and “γραµµή” for streak) reflects the characteristic pattern of the blue luminous tissue on the ventral side of the body. Comparisons. Photonectes cyanogrammicus is similar to P. gracilis and P. sphaerolampas in possession of transverse streaks of blue luminous tissue alternating with photophores of ventral rows, but differs from both these species in presence of diffuse indistinct lateral band of blue tissue from behind the level of pelvic-fin origin to the caudal-fin base, with irregular ventral extensions forming a reticulate appearance anteriorly (before level of midbase of dorsal- and anal-fins) (vs. distinct solid lateral band of blue tissue from gill opening to caudal-fin base). Furthermore, P. cyanogrammicus differs from P. gracilis and P. sphaerolampas in higher VAV and lower AC count (16 and 9 vs. 12–15 and 12–13, and 12–15 and 14–18, respectively), and from P. gracilis in more posterior position of pelvic fins (prepelvic length 60.7% SL vs. 51.5–56.8% SL). Distribution. This species is known only from the holotype collected in the Equatorial Western Pacific.Published as part of Prokofiev, Artem M. & Klepadlo, Cynthia, 2019, Two new species of Photonectes with blue luminous tissue on body, and a re-examination of P. mirabilis (Teleostei: Stomiidae), pp. 270-282 in Zootaxa 4590 (2) on pages 271-273, DOI: 10.11646/zootaxa.4590.2.4, http://zenodo.org/record/265199

Photonectes Prokofiev & Klepadlo 2019

Key for identification of the species of Photonectes with blue luminous tissue on body 1a Barbel expanded toward tip, lacking bulbs or whip-like unpigmented terminal appendage, but unpigmented and apparently luminous in distal portion (Fig. 1G); blue luminous tissue consisting of a longitudinal row of interrupted streaks on each side above IV photophores, and transverse interrupted streaks connecting longitudinal lines of left and right sides of body between photophores of ventral rows, alternating with photophores (Fig. 1C); lateral longitudinal band of blue tissue diffuse and irregular (Fig. 1D), not extending anteriad from vertical of pelvic-fin origin............................ P. cyanogrammicus 1b Barbel with bulb(s) and/or unpigmented whip-like terminal appendage twice or more narrower than the pigmented stem of barbel; blue luminous tissue of different arrangement........................................................... 2 2a Solid longitudinal band of blue luminous tissue present on flanks between gill opening and caudal-fin base (Fig. 9A)...... 3 2b No such band........................................................................................ 4 3a Barbel lacking bulb, with thin unpigmented terminal filament splitting on tip into three short filaments; barbel not exceeding eye in length................................................................................. P. gracilis 3b Barbel with large spherical bulb bearing thin solidly pigmented terminal filament splitting on tip into four short filaments; barbel much longer than eye................................................................. P. sphaerolampas 4a Barbel with several bulbs of different size and a short dorsal branch (Fig. 7); blue luminous tissue on body consisting of a pair of longitudinal lines between IP photophores and a longitudinal row of spots (sometimes confluent into line) on each side above PV photophores; 3 pairs of spots of luminous tissue inside mouth (Figs. 6C, 6D) and a spot above last BR photophore (Fig. 6F)................................................................................... P. mirabilis 4b Barbel with a single large bulb or without bulbs; blue luminous tissue on body of different arrangement; no luminous spots inside mouth and on branchiostegal membrane (except P. achirus).............................................. 5 5a Blue luminous tissue consisting of a pair of lines along midline of isthmus (Fig. 9B), running outward of IP photophores at 1 st –2 nd organs of this series and disappearing above the last IP photophores.............................. P. venetaenia 5b Blue luminous tissue consisting of a midventral chevron-shaped stripe between PV photophores with short transverse streaks alternating with photophores, and a row of spots on each side above PV photophores (Fig. 9C)....................... 6 6a Barbel with large bulb, a pair of luminous spots inside mouth and a patch of luminous tissue in front of BR-1; BR 6–8.................................................................................................. P. achirus 6b Barbel without bulb, no luminous spots inside mouth, no patch of luminous tissue in front of BR-1; BR 8–10..................................................................................................... P. caerulescensPublished as part of Prokofiev, Artem M. & Klepadlo, Cynthia, 2019, Two new species of Photonectes with blue luminous tissue on body, and a re-examination of P. mirabilis (Teleostei: Stomiidae), pp. 270-282 in Zootaxa 4590 (2) on page 280, DOI: 10.11646/zootaxa.4590.2.4, http://zenodo.org/record/265199