Chromis tingting, Tea & Gill & Senou, 2019

Tea, Yi-Kai, Gill, Anthony C. & Senou, Hiroshi, 2019, Chromis tingting, a new species of damselfish from mesophotic coral ecosystems of southern Japan, with notes on C. mirationis Tanaka (Teleostei: Pomacentridae), Zootaxa 4586 (2), pp. 249-260 : 251-258

publication ID	https://doi.org/ 10.11646/zootaxa.4586.2.2
publication LSID	lsid:zoobank.org:pub:641BC4A0-8AB0-43D0-AD36-4E6249DF91DC
persistent identifier	https://treatment.plazi.org/id/437650F8-8912-4FBD-83E8-6BC5F09F14E8
taxon LSID	lsid:zoobank.org:act:437650F8-8912-4FBD-83E8-6BC5F09F14E8
treatment provided by	Plazi
scientific name	Chromis tingting
status	sp. nov.

Treatment

Chromis tingting sp. nov.

New standard Japanese name: Gekko-suzumedai

English common name: Moonstone Chromis

Figures 2–8 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 View FIGURE 8 , Tables 1–2 View TABLE 1 View TABLE 2

Chromis mirationis View in CoL [non Tanaka 1917]; Song et al. 2014: 2, figs 1a–c and 2, table 1 (larval description and identification).

Holotype. KPM-NI 30 View Materials 479, 53.6 mm SL, Japan, Shizuoka Prefecture, west side of Sagami Bay, east side of Izu Peninsula , 58 m, W. Takase, 15 March 2012.

Paratypes. KPM-NI 18916 View Materials , 98.5 View Materials mm SL, Japan, Shizuoka Prefecture, west side of Sagami Bay, off Hatsushima Island , 30–40 m, Y. Miyazaki, 30 April 2007 ; KPM-NI 23617 View Materials , 25.4 View Materials mm SL, Japan, west side of Sagami Bay, east side of Izu Peninsula, Izu Oceanic Park , 50 m, W. Takase, 23 March 2009 ; KPM-NI 32613 View Materials , 15.5 View Materials mm SL, Japan, west side of Sagami Bay, east side of Izu Peninsula, Jogasaki coast, 65 m, 15 January 1990 .

Diagnosis. The following combination of characters distinguishes C. tingting from all congeners: dorsal rays XIV,13–14; anal rays II,12; pectoral rays 19–20; tubed lateral-line scales 15–17; gill rakers 5–6 + 17–20 = 22–26; caudal fin with two spinous procurrent rays dorsally and ventrally. Chromis tingting can be further distinguished from congeners based on color patterns, and in having a large black spot on the pectoral fin base that reaches the lower limits of the axil.

Description. Dorsal rays XIV,13–14 (XIV,13), all segmented rays branched except only last 8 in smallest paratype; anal rays II,12, all segmented rays branched; pectoral rays 19–20 (20/20), the upper 2–3 (2/2) and lower 2–3 (2/2) unbranched; pelvic rays I,5; principal caudal rays 8 + 7, the upper and lower rays unbranched; upper and lower procurrent caudal rays 4, the anteriormost 2 rays (dorsally and ventrally) spiniform; tubed lateral-line scales 15–17 (17/17); posterior mid-lateral scales with a pore or deep pit 6–8 (8/6); scales above lateral line to origin of dorsal fin 3.5; scales below lateral line to origin of anal fin 11–12 (11/12); gill rakers 5–6 + 17–20 = 22–26 (16 + 19); vertebrae 11 + 15; predorsal formula (after Ahlstrom et al., 1976) 0/0/0 + 1/1+1; ribs present on vertebrae 3 through 10; epineurals present on vertebrae 1 through 15.

Body moderately deep, depth 1.9–2.0 (2.0) in SL, and compressed, the width 2.9–4.7 (3.5) in body depth; head length 2.5–3.0 (3.0) in SL; dorsal profile of head with convexity anterior to eye and concavity dorsal to eye; snout shorter than orbit diameter, its length 3.7–5.7 (3.9) in HL; orbit diameter 2.1–2.4 (2.2) in HL; interorbital space convex, its width 2.8–3.7 (3.4) in HL; caudal peduncle depth 2.3–2.9 (2.3) in HL; caudal peduncle length 2.7–2.9 (2.7) in HL.

Mouth terminal, small, oblique, the upper jaw forming an angle of about 45° to horizontal axis of head and body; posterior edge of maxilla reaching slightly beyond a vertical at anterior edge of pupil, the upper jaw length 2.8–3.4 (3.4) in head; upper jaw with 4–5 rows of small conical teeth at symphysis, reducing to single row posteriorly, the teeth of outer row enlarged and slightly curved; lower jaw with 3–4 rows of small conical teeth, reducing to single row posteriorly, the outer row teeth enlarged and slightly curved; about 20–25 outer row teeth on each side of upper and lower jaws; tongue triangular with rounded tip; gill rakers long and slender, the longest on lower limb near angle about four-fifths length of longest gill filaments; anterior nostril with a slightly raised rim fleshy rim, more elevated on posterior edge and located at level of middle of pupil, about one-third distance from front of snout to base of upper lip; posterior nostril a vertical slit, at about horizontal through upper edge of pupil; an enlarged slit-like opening of the frontal portion of the latero-sensory canal present above middle of eye (termed “crescent opening of supraorbital canal” by Randall et al., 1981; Figure 3 View FIGURE 3 ).

Opercle ending posteriorly in a flat spine, the tip relatively obtuse and obscured by a large scale; margin of preopercle smooth, the posterior margin extending dorsally to just above upper edge of pupil; suborbital with free lower margin extending to vertical through middle of pupil ( Figure 3 View FIGURE 3 ).

Scales spinoid in smallest paratype, ctenoid with transforming cteni (after Roberts, 1993) in remaining specimens); anterior lateral line ending beneath rear portion of spinous dorsal fin (beneath thirteenth to fourteenth dorsal-fin spines); head scaled except lips, tip of snout, and a narrow zone from orbit to edge of snout containing nostrils ( Figure 3 View FIGURE 3 ); a scaly sheath at base of dorsal and anal fins, about half pupil diameter at base of middle of spinous portion of dorsal fin; two columns of scales on each membrane of dorsal fin, narrowing distally, those on spinous portion of dorsal progressively longer, reaching about two-thirds distance to spine tips on posterior membranes; scales on anal-fin membrane in one column, scales progressively smaller distally; small scales on caudal fin extending to about one-half distance to posterior margin; small scales on basal one-fifth of pectoral fins; a median scaly process extending posteriorly from between base of pelvic fins, its length a little over one-third that of pelvic spine; axillary scale above base of pelvic spine about one-third length of spine.

Origin of dorsal fin over first or second lateral-line scale, the predorsal length 2.1–2.4 (2.4) in SL; dorsal fin base contained 1.5–1.8 (1.5) in SL; base of soft portion of dorsal fin contained 5.8–6.5 (5.8) in SL; first dorsal spine 3.0–3.9 (3.1) in HL; second dorsal spine 2.0–2.4 (2.0) in HL; third dorsal spine 1.7–2.2 (1.7) in HL; fourth dorsal spine 1.7–2.0 (1.7) in HL; fifth dorsal spine 1.7–2.0 (1.7) in HL; sixth dorsal spine 1.7–2.0 (1.7) in HL; fourteenth dorsal spine 2.1–3.5 (2.4) in HL; membranes of spinous portion of dorsal fin moderately incised; first segmented dorsal ray 1.8–2.3 (1.8) in HL; fourth or fifth dorsal segmented ray longest, its length 1.4–1.6 (1.4) in HL; preanal length 1.4–1.5 (1.4) in SL; anal fin base 4.1–4.5 (4.1) in SL; first anal spine 3.2–5.3 (3.2) in HL; second anal spine nearly twice as long as first, 1.4–2.2 (1.4) in HL; first anal segmented ray 1.5–1.9 (1.5) in HL; third, fourth or fifth segmented anal ray the longest, its length 1.4–1.7 (1.4) in HL; caudal fin forked, its length 2.6–2.9 (2.7) in SL, the caudal concavity 6.2–6.8 (6.2) in SL; third or fourth pectoral-fin ray longest, 2.9–3.2 (2.9) in SL; prepelvic length 2.2–2.4 (2.4) in SL; pelvic spine 1.7–2.1 (1.7) in HL; first segmented ray of pelvic fin filamentous, usually reaching to base of first or second anal-fin ray, its length 2.3–3.1 (3.1) in SL.

Coloration of adults in life (based on color photographs of the holotype and largest paratype when freshly dead, and photos of live individuals taken in the field and aquaria; Figures 2 View FIGURE 2 , 4–5 View FIGURE 4 View FIGURE 5 , 7A View FIGURE 7 2 View FIGURE 2 ): head and body bluish grey to dark grey, overlain with silvery-white to whitish-blue iridescence when alive; iris dusky silver-grey, bright yellow dorsally in life, with narrow blue ring around pupil; short yellow stripe from tip of snout to anterior edge of orbit, becoming diffused behind orbit and continuing across upper part of preopercle and operculum to anterior few lateral line scales and upper part of pectoral fin base (yellow markings not apparent in 98.5 mm SL paratype); axil of pectoral fin base with large black spot; spinous dorsal fin and scale-sheath area of soft dorsal dark yellowish grey to black, the remainder of soft dorsal yellowish or greyish hyaline to hyaline; distal part of spinous dorsal greyish yellow to bright yellow in young adults, this broadest anteriorly, gradually narrowing posteriorly, with distal margin of fin narrowly blue; anal fin pale yellowish grey to yellow, broadly edged distally with paler bluish grey to pale blue; caudal fin greyish yellow to bright yellow, bluish to greyish hyaline on distal margin; pelvic fins pale blue to bluish or greyish hyaline; pectoral fins bright yellow basally, the remainder of fin yellowish to greyish hyaline.

Coloration of juveniles in life (based on color photographs of two smaller paratypes when freshly dead, and photos of individuals taken in the field and aquaria; Figures 6 View FIGURE 6 , 7A View FIGURE 7 1 View FIGURE 1 ): head and body entirely gunmetal to silverygrey, overlaid with greenish blue iridescence dorsally; iris pale blue to grey, bright metallic blue on dorsal edge; axil of pectoral fin base with large black spot; caudal peduncle greyish yellow to bright yellow posteriorly; dorsal bright yellow, with basal part of spinous part of fin greyish yellow in larger juveniles; anal fin bright yellow; caudal fin bright yellow basally with remainder of fin hyaline in small juveniles, the yellow area becoming more extensive to cover most of fin in larger juveniles; pectoral fins hyaline; pelvic fins greyish hyaline, edged in pale blue.

Coloration in alcohol: head and body pale brown to dark grey-brown, paler ventrally; dark grey spot on pectoral axil remains; dark yellowish grey to black basal marking on dorsal fin remains, becoming greyish brown, the remainder of fins brown to brownish hyaline.

Etymology. Named in honor of the first author’s mother, in recognition of her unconditional love, support and encouragement. To be treated as a noun in apposition. The common name Moonstone Chromis refers to the pearlescent, silvery-blue coloration of the juveniles and adults of this species. “Gekko”, of the new standard Japanese name, means moonlight in Japanese.

Habitat and distribution. Chromis tingting is described on the basis of four specimens from Sagami Bay, Japan. Underwater photographs in the Image Database of Fishes, Kanagawa Prefectural Museum of Natural History (KPM) indicates that the species also occurs in Suruga Bay (KPM-NR 84548) and the Ryukyu Archipelago (Izena Bank, Okinawa). Underwater photos indicate that it also occurs in Hachijo-Jima in the Izu Archipelago ( Figure 7A View FIGURE 7 1 View FIGURE 1 ) and Kashiwajima, Kochi, Japan ( Figure 6 View FIGURE 6 ). It probably also occurs in Korea, based on a larval specimen from south of Tong-young, Korea Strait (see remarks below; Figure 8 View FIGURE 8 ). The species frequents deep reefs with some sponge and coral cover, at depths reaching 86 m, though it has been infrequently recorded at shallower depths of 25 m. It is frequently seen in the company of species of the genera Sacura Jordan & Richardson 1910, Pseudanthias Bleeker 1871 , Tosanoides Kamohara 1953 and Pseudolabrus Bleeker 1862 .

Comparisons. Chromis tingting is one of several deep-water Chromis with 14 dorsal fin spines. Lecchini & Williams (2004) listed 20 species in which at least some specimens had been recorded with 14 spines, including their new species Chromis planesi . An additional five species of Chromis with 14 dorsal fin spines have been described since: Chromis onumai Senou & Kudo (2007) , C. abyssus Pyle et al. (2008) , C. circumaurea Pyle et al. (2008) , C. degruyi Pyle et al. (2008) , and C. unipa Allen & Erdmann (2009) . Of these species, C. tingting , most closely resembles C. mirationis Tanaka (1917) , C. okamurai Yamakawa & Randall (1989) and C. struhsakeri Randall & Swerdloff (1973) in coloration and in having similar tubed lateral-line scale and fin-ray counts (including only two versus three spinous caudal rays dorsally and ventrally).

All four species have mostly white to greyish-blue adults but are easily separated based on color patterns ( Figure 7 View FIGURE 7 ; Table 2 View TABLE 2 ). Chromis tingting differs from all three species in having a larger eye (13.7–19.4% SL versus 12.2–14.5% SL in C. mirationis , 13.6% SL in C. okamurai , and 12.0–15.6% SL in C. struhsakeri ), fewer gill rakers (5–6 + 17–20 = 22–26 versus 8–9 + 19–21 = 27–30 in C. mirationis , 8 + 19 = 27 in C. okamurai , and 7–8 + 22–26 = 29–34 in C. struhsakeri ), and further from C. mirationis and C. okamurai in having a more restricted free margin of the suborbital (to beneath middle of pupil versus to well past vertical through posterior edge of pupil).

Remarks. Song et al. (2014) identified a larval specimen of an unidentified Chromis from south of Tongyoung, Korea Strait, Korea as C. mirationis . However, the basis for their identification was a sequence match in mtDNA (16S ribosomal RNA) with a specimen identified as C. mirationis . That comparative specimen is the holotype of C. tinging (KPM-NI 30479), and the match therefore suggests that the larval specimen is C. tingting . However, no specimens of C. mirationis were included in their analysis, and we therefore consider this conclusion tentative.

The GenBank registration numbers for both specimens of Chromis tingting in Song et al. (2014) are JQ178234 View Materials and KF957467 View Materials respectively (the latter is the holotype, previously misidentified as C. mirationis ). Based on their neighbor joining tree of mitochondrial 16S sequences, Chromis tingting is most closely related to C. notata (d =0.017; d is genetic distance). However, no specimens of C. mirationis , C. okamurai or C. struhsakeri were included in their analysis, and comparative genetic sequences for those species are lacking. We therefore consider the relationship proposed in Song et al. (2014) as tentative, and the relationship proposed here between C. tingting , C. mirationis , C. okamurai and C. struhsakeri as putative pending further study.