Photonectes (Photonectes) banshee, Koeda & Ho, 2019

Koeda, Keita & Ho, Hsuan-Chign, 2019, Photonectes banshee, a new species of the subgenus Photonectes (Stomiiformes: Stomiidae: Melanostomiinae) from Taiwan, Zootaxa 4586 (1), pp. 180-186 : 181-185

Photonectes (Photonectes) banshee sp. nov.

Figures 1–5 ; table 1

Holotype. NMMB-P 27334 , 124.7 mm SL, off Dong-gang (ca. 22°39ʹN, 120°24ʹE), Pingtung , South China Sea, Taiwan, 20 October 2017, mid-water trawl, obtained at fish-landing ground at Dong-gang, collected by K. Koeda.

Paratypes. NMMB-P30103 , 77.3 mm SL, collection locality and method same as holotype, 1 August 2018, collected by K. Koeda, H.- C. Ho, and L. C. Halasan ; KAUM–I. 125098, 117.0 mm SL (barbel and most of photophores damaged), collection locality and method same as holotype, 26 December 2018, collected by K. Koeda and H. Hata.

Diagnosis. A member of the subgenus Photonectes based on the following combination of characters: dorsal- and anal-fin rays not covered with black fleshy skin; pectoral fins absent; pelvic fins inserted closer to the caudalfin than snout; IV photophores 31; and IP photophores begin halfway along isthmus length. Within the subgenus, P. banshee differs from its congeners with the following combination of characters: dorsal-fin rays 19–20; anal-fin rays 22–23; body slender, its maximum depth 8.6–12.0% SL; gill filaments of first branchial arch normal, not extending beyond opercular opening; barbel short, its length 35.5–54.9% HL; stem of barbel without discernible secondary light organs; barbel ends in leaf-like flap with single terminal filament; IV 31 (IP 6 + PV 25); VAV 10; AC 14; BR 9; OA 30 (OV 21 + VAL 9); white luminous tissue on posterodorsal opercle absent; blue luminous tissue in short vertical streak between PV photophores, not forming longitudinal stripe; longitudinal series of blue luminous tissue in short bars from sides of isthmus to below 7th OV photophore; blue luminous tissue also present under lower jaw, and in area posterior to gill-opening; blue luminous tissue above end of maxillary absent.

Description. Counts and measurements of P. (Photonectes) banshee are given in Table 1 . The description and data for the holotype are presented first, followed by that of paratypes in parentheses when different.

Body very slender, its depth about 8 (10) times at middle of body (just posterior to preopercle or middle of body); body and head strongly compressed laterally; dorsal and ventral outlines of body slightly convex at middle of body (almost straight), very gradually tapering posteriorly; caudal peduncle shallow, its depth almost five times in maximum body depth.

Dorsal-fin origin slightly posterior to anal-fin origin; posterior end of anal-fin base located below middle of caudal peduncle; dorsal and anal fins about same size and shape, fin rays shorter than maximum body depth but longer than body depth at anal-fin origin; fins not covered with black fleshy skin; pectoral fin absent; pelvic-fin base located at almost posterior third of body; distal tip of depressed pelvic fin not reaching anal-fin origin; caudal fin forked, lower lobe longer than upper.

Eye rounded; snout very short and abrupt ( Fig. 3 ); mouth very large, strongly oblique; lower jaw longer than upper jaw and strongly curved dorsally, its tip reaching to same level of dorsal outline of head. Opercle thin, flaplike; gill filaments very long and twisted, well extending beyond opercular opening, but normal and not extending beyond opercular opening on first branchial arch.

Premaxillary with nine (eight) teeth, in two rows, five (four) teeth in inner row, very sharp, curved and moderately oblique to posterior, longer than maxillary and mandibular teeth; four teeth in outer row sharp, curved, but half length of inner teeth; maxillary teeth sharp, mostly equal or shorter than mandibular teeth, strongly oblique in posterior half; mandibular teeth very sharp, moderately oblique; vomer with single pair (two pairs) of teeth; palatine with single pair of sharp and well oblique teeth; two pairs (patches) of basibranchial teeth, large gap between pairs (patches: anterior patch with two long and four short teeth; posterior patch with two long teeth and a single short one).

Barbel located at about anterior almost 1/2 (1/3) of lower jaw; barbel short, its length 2.8 (1.6) times in HL; stem without discernible secondary light organs; barbel ends with single bulb (flattened, leaf-like; Fig. 4 ) and a single distal filament, its length about half stem length.

Last two photophores of VAL over anal-fin base; IP series with gap, begins posteriorly about halfway along isthmus length; postorbital photophore oval-shape, distinctly shorter in length compared to eye diameter; preopercular photophore absent; single subopercular photophore; blue luminous tissue in short vertical streak between PV photophores ( Fig. 5 ), not forming longitudinal stripe; blue luminous tissue in short longitudinal bars lined from sides of isthmus to below 7th OV photophore, under lower jaw, and area posterior to gill-opening; blue luminous tissue absent above end of maxillary.

Fresh coloration. Body and head uniformly black; iris, oral cavity, and gill filaments black; barbel black at basal half and terminal filament, semi-translucent white at distal half; photophores on body white or yellow; postorbital and subopercular photophores faint pink. Photophores white after preservation.

Etymology. The specific name banshee is a name of female spirit in Irish mythology meaning “keening fairy or female” in Old Irish. This refers to the series of blue luminous tissue on ventral side of the body of the specimens that resemble the tears of the keening fairy.

Distribution. Photonectes banshee sp. nov. is currently only known from southwestern Taiwan. The holotype and paratypes were collected in the upper 100 m by a mid-water trawl targeting Sakura-shrimp ( Lucensosergia lucens ).

Remarks. The species of the genus Photonectes are often difficult to identify because the large adults have rather deep and flaccid bodies that are subject to damage during sampling, most often the barbel, the ventrolateral photophores, or the luminous tissue are damaged or lost. In addition, the shape of the barbel may have ontogenetic variations in some species ( Prokofiev 2014). Klepadlo (2011) combined some additional available characters to identify them and reviewed the diagnostic characters of subgenera and species of Photonectes based on their examination and previous references ( Regan & Trewavas 1930; Morrow & Gibbs 1964; Gibbs 1968). Of the 11 species recognized in the subgenus Photonectes ( Flynn & Klepadlo 2012; Prokofiev 2016), P. banshee is unique in having fewer numbers of IP (6 vs. 7–13 in congeners of subgenus), VAV (10 vs. 11–16) and VAL (10 vs. 11–15). In addition, P. banshee has more than two definitive differences from other species of subgenus: differs from all congeners except for Photonectes phyllopogon Regan & Trewavas 1930 by 19–20 dorsal-fin rays and 22–23 analfin rays (vs. 11–19 dorsal-fin rays and 12–21 anal-fin rays); from Photonectes achirus Regan & Trewavas 1930 , Photonectes albipennis (Döderlein 1882) , Photonectes barnetti Klepadlo 2011 , Photonectes coffea Klepadlo 2011 , Photonectes paxtoni Flynn & Klepadlo 2012 , Photonectes venetaenia Prokofiev 2016 , and Photonectes waitti Flynn & Klepadlo 2012 by lacking white luminous tissue on posterodorsal opercle (vs. 1 or 2); from P. albipennis , P. barnetti , P. coffea , Photonectes corynodes Klepadlo 2011 , P. paxtoni , P. phyllopogon , and P. waitti by presence of blue luminous tissue at midventral body (vs. absent); from P. achirus , P. barnetti , Photonectes caerulescens Regan & Trewavas 1930 , P. coffea , Photonectes mirabilis Parr 1927 , P. paxtoni , P. phyllopogon , and P. waitti by having normal gill filament length (vs. very short or very long).

Despite the above mentioned characters, P. banshee is most similar to P. caerulescens which is known from the north Atlantic Ocean at 1000 m depth. These two species share the absence of white luminous tissue on posterodorsal opercle, presence of blue luminous tissue at midventral body, and short barbel. However, the new species differs from P. caerulescens in not only the counts of fin rays and photophores shown above but also in the pattern of blue luminous tissue. Blue luminous tissue on the midventral of P. banshee forms a short vertical streak between PV photophores, versus that of P. caerulescens forms a single longitudinal mid-ventral stripe from chest to pelvic fins with transverse streaks. In addition, P. banshee lacks blue luminous tissue above the end of maxillary, which is present in P. caerulescens .

The barbel of P. banshee is most similar to P. barnetti ( Klepadlo 2011: fig. 8) in having a single white bulb with a single elongate distal filament. However, P. banshee has a shorter barbel (vs. length longer than HL in P. barnetti ), small bulb (vs. large ovoid bulb), stem entirely pigmented (vs. middle third unpigmented), and distal filament pigmented (vs. pale).

Figures

FIGURE 1. Fresh holotype of Photonectes banshee sp. nov. from southwestern Taiwan. NMMB-P27334, 124.7 mm SL (photograph reversed the direction to left).

FIGURE 2. Fresh paratypes of Photonectes banshee sp. nov. from southwestern Taiwan. Upper two: NMMB-P30103, 77.3 mm SL; lower two: KAUM–I. 125098, 117.0 mm SL.

FIGURE 3. Head of types of Photonectes banshee sp. nov. Left: NMMB-P27334, holotype, 124.7 mm SL (photograph reversed the direction to left); middle: NMMB-P30103, paratype, 77.3 mm SL; right: KAUM–I. 125098, paratype, 117.0 mm SL.

FIGURE 4. Left lateral view of barbel of paratype of Photonectes banshee sp. nov. NMMB-P30103, 77.3 mm SL.

FIGURE 5. Position of blue luminous tissues of Photonectes banshee sp. nov. Yellow spots indicating OV and PV.