Pseudochromis oligochrysus, Gill, Anthony C., Allen, Gerald R. & Erdmann, Mark, 2012

Gill, Anthony C., Allen, Gerald R. & Erdmann, Mark, 2012, Two new dottyback species of the genus Pseudochromis from southern Indonesia (Teleostei: Pseudochromidae), Zootaxa 3161, pp. 53-60 : 53-57

publication ID	https://doi.org/ 10.5281/zenodo.211327
DOI	https://doi.org/10.5281/zenodo.6167123
persistent identifier	https://treatment.plazi.org/id/7322879C-FF9E-FFB0-FF11-6218A9694941
treatment provided by	Plazi
scientific name	Pseudochromis oligochrysus
status	sp. nov.

Treatment

Pseudochromis oligochrysus View in CoL sp. nov.

Gold-ring Dottyback

Figures 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 ; Table 1

Holotype. MZB 20567, 49.8 mm SL, Indonesia, Nusa Penida, Mangrove Point, 08°40’S 115°28’E, 45–50 m, M.V. Erdmann, 8 May 2008.

Paratypes. WAM P.33099-003, 2: 50.0–57.0 mm SL, Indonesia, Nusa Penida, Mangrove Point, 08°40’S 115°28’E, 60–70 m, M.V. Erdmann, 21 November 2008; WAM P.33101-002, 2: 49.5–50.8 mm SL, Indonesia, Nusa Penida, Crystal Bay South, 08°43’S 115°27’E, 25–50 m, M.V. Erdmann, 26 November 2008; AMS I.45680- 0 0 1, 1: 47.0 mm SL, collected with holotype; WAM P.33016-001, 1: 40.5 mm SL, collected with holotype; WAM P.33399-001, 2: 45.2–52.6 mm SL, Indonesia, Pantar Strait, Pura Island, 08°19’S 124°22’E, 40 m, M.V. Erdmann, 26 March 2011.

Diagnosis. A species of Pseudochromis with the following combination of characters: dorsal-fin rays III,25– 27, usually III,26; anal-fin rays III,16; circumpeduncular scales 16; horizontal scale rows above anal-fin origin 13– 15 + 1 + 3 = 17–19; predorsal scales 21–27; caudal fin rounded; dark spot on upper part of pectoral-fin base; and yellow spots or markings on anterior body.

Description (based on nine specimens, 40.5–57.0 mm SL; data for all types followed, where variation was noted, by data for holotype in parentheses; counts recorded bilaterally from the holotype are given separated by a slash, firstly the left side). Dorsal-fin rays III,25–27 (III,27), all segmented rays branched; anal-fin rays III,16, all segmented rays branched; pectoral-fin rays 18–19 (19/19); upper procurrent caudal-fin rays 6–8 (7); lower procurrent caudal-fin rays 6–8 (6); total caudal-fin rays 29–33 (30); scales in lateral series 34–40 (36/35); anterior lateral-line scales 27–32 (28/28); anterior lateral line terminating beneath segmented dorsal-fin ray 18–22 (21/21); posterior lateral-line scales 6–7 + 0–2 (6 + 1/6 + 0); scales between lateral lines 2–3 (3/3); horizontal scale rows above anal-fin origin 13–15 + 1 + 3 = 17–19 (13 + 1 + 3/13 + 1 + 3); circumpeduncular scales 16; predorsal scales 21–27 (22); scales behind eye 3; scales to preopercular angle 4–6 (5); gill rakers 5–6 + 11–13 = 16–18 (5 + 12); pseudobranch filaments 9–12 (11); circumorbital pores 23–32 (27/28); preopercular pores 10–13 (12/13); dentary pores 4; posterior interorbital pores 1–2 (2).

Lower lip incomplete, with weak to moderate symphyseal interruption; dorsal and anal fins without scale sheaths, although sometimes with intermittent scales overlapping fin bases; predorsal scales extending anteriorly to point ranging from posterior nostrils to midway between posterior and anterior nostrils; opercle with 4–6 relatively indistinct serrations; teeth of outer ceratobranchial-1 gill rakers well developed only on tips; anterior dorsal-fin pterygiophore formula S/S/S + 3/1 + 1/1/1/1/1 + 1*/1 (S/S/S + 3/1 + 1/1/1/1/1 + 1/1); dorsal-fin spines moderately stout to stout and pungent; anterior anal-fin pterygiophore formula 3/1 + 1/1 + 1*/1 (3/1 + 1/1/1 + 1); anal-fin spines moderately stout to stout and pungent, second spine stouter than third; pelvic-fin spine moderately stout to stout and pungent; second segmented pelvic-fin ray longest or subequal to third; caudal fin rounded; vertebrae 10 + 16; epineurals 13–14 (14); epurals 3.

Upper jaw with 2–4 pairs of curved, enlarged caniniform teeth anteriorly, and 5–6 (at symphysis) to 2–3 (on sides of jaw) inner rows of small conical teeth, outermost of rows of conical teeth much larger and more curved than inner rows; lower jaw with 1–3 pairs of curved, enlarged caniniform teeth anteriorly, and 4–6 (at symphysis) to 1 (on sides of jaw) inner rows of small conical teeth, teeth on middle of jaw slightly larger and curved; vomer with 1–3 rows of small conical teeth, forming chevron; palatines with 1–3 rows of small conical teeth arranged in elongate, suboval patch, anterior part of tooth patch more-or-less contiguous with posterolateral arm of vomerine tooth patch; ectopterygoid edentate; tongue moderately pointed and edentate.

As percentage of SL: head length 22.6–28.4 (24.7); orbit diameter 8.9–10.6 (9.6); snout length 5.8–6.9 (6.0); fleshy interorbital width 5.9–6.8 (6.6); bony interorbital width 4.2–5.3 (4.8); body width 12.0–14.4 (13.1); snout tip to posterior tip of retroarticular bone 13.5–15.0 (13.5); predorsal length 31.5–35.3 (32.3); prepelvic length 29.3– 32.8 (29.3); posterior tip of retroarticular bone to pelvic-fin origin 16.5–20.7 (16.5); dorsal-fin origin to pelvic-fin origin 29.1–32.3 (31.3); dorsal-fin origin to middle dorsal-fin ray 33.7–39.1 (36.9); dorsal-fin origin to anal-fin origin 42.0–45.1 (44.2); pelvic-fin origin to anal-fin origin 26.0–33.2 (31.3); middle dorsal-fin ray to dorsal-fin termination 23.5–27.7 (25.7); middle dorsal-fin ray to anal-fin origin 26.6–29.8 (29.1); anal-fin origin to dorsal-fin termination 35.1–38.0 (35.3); anal-fin base length 26.7–31.4 (28.1); dorsal-fin termination to anal-fin termination 14.6–16.9 (16.7); dorsal-fin termination to caudal peduncle dorsal edge 9.9–12.3 (11.0); dorsal-fin termination to caudal peduncle ventral edge 18.6–20.5 (20.3); anal-fin termination to caudal peduncle dorsal edge 19.9–21.4 (21.1); anal-fin termination to caudal peduncle ventral edge 11.2–12.8 (12.4); first dorsal-fin spine 1.8–3.0 (2.2); second dorsal-fin spine 4.2–6.2 (4.8); third dorsal-fin spine 6.6–8.6 (6.8); first segmented dorsal-fin ray 9.1–12.8 (10.4); fourth last segmented dorsal-fin ray 15.9–17.9 (16.3); first anal-fin spine 1.4–3.0 (3.0); second anal-fin spine 3.4–6.0 (5.0); third anal-fin spine 4.8–7.2 (broken); first segmented anal-fin ray 9.0–12.1 (9.0); fourth last segmented anal-fin ray 13.8–17.3 (14.1); third pectoral-fin ray 13.8–16.8 (14.5); pelvic-fin spine 9.3–11.9 (10.2); second segmented pelvic-fin ray 19.9–23.8 (21.1); caudal-fin length 23.0–28.3 (28.3).

Live coloration (based on photographs of type specimens and other individuals from Nusa Penida and Pantar Strait when alive, Figures 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 ): head and body dark olive, becoming purplish grey ventrally and posteriorly; orbital rim narrowly bright yellow, this edged broadly posteriorly and ventrally with bluish to purplish grey curved bar; curved bar in turn edged with bright yellow curved bar or series of spots; remainder of cheek and operculum with pale to bright yellow spots, which sometimes align to form short bars or stripes; iris brown to orange with blue suboval ring around pupil; pectoral-fin base grey, becoming darker grey to black dorsally and in axil of fin; scales of anterior body each with pale yellow central spot; in some individuals (from Pantar Strait) yellow is brighter and confined to dorsal and ventral edges of scales, which combine with darker purplish grey remainder of scale to form alternating bright yellow and purplish grey stripes on anterior body; caudal peduncle and posterior part of body sometimes reddish brown to orange dorsally; dorsal-fin rays orange to yellow, the membranes olive-grey, sometimes becoming reddish brown to orange posteriorly and yellowish to orange-brown distally, with broad grey stripe through middle of fin; dark grey-blue spot behind base of each dorsal-fin ray; distal margin of dorsal fin narrowly bluish grey; anal fin pale blue to pale grey basally, the remainder of fin dark grey to blue grey, with one or two yellow stripes through basal half of fin and yellow stripe edging blue to blue-grey distal margin of fin; caudal fin dark purplish grey, broadly pale yellow to pale orange ventrally and dorsally, with bluish grey to blue distal margin; pectoral fins pinkish to reddish hyaline; pelvic fins bright yellow with anterior margin bluish grey to blue.

Preserved coloration: pattern similar to live coloration, head and body becoming grey-brown, paler ventrally on abdomen and lower head; yellow to orange markings remain, becoming pale brown to pale yellow; purplish to bluish grey or grey markings on head, anterior body and fins become dark grey-brown.

Habitat and Distribution. Pseudochromis oligochrysus is known only from a few scattered localities in the Lesser Sunda Islands of southern Indonesia, including Nusa Penida and Menjangan Islands off the coast of Bali and from Tanjung Watuili in south Pantar and Pura Island in the Pantar Strait, between Pantar and Alor. It was observed between 25 and 50 m depth (typically below 40 m), exclusively on reefs subject to strong currents and frequent cold-water upwellings. The species was always found in association with coral overhangs or large rubble pieces on hard bottom substrates, and would retreat under the rubble or overhang when approached. Its habitat preferences seem very narrowly defined; in recent intensive surveys around the island of Bali the species was only observed at 4 of 47 sites surveyed (all on Nusa Penida and Menjangan islands) - each with strong currents, cold upwelling and hard bottoms.

Comparisons. Pseudochromis oligochrysus closely resembles P. flavopunctatus Gill and Randall (1998) in having the following combination of characters: segmented dorsal-fin rays 25–27, usually 26; segmented anal-fin rays 16; circumpeduncular scales 16; caudal fin rounded; dark spot on upper part of pectoral-fin base; and yellow spots or markings on anterior body. It is readily distinguished from P. flavopunctatus in have more horizontal scale rows scales above the anal-fin origin (13–15 + 1 + 3 = 17–19 versus 10–12 + 1 + 2–3 = 13–16) and more predorsal scales (21–27 versus 16–22). Moreover, the two species differ in live coloration details: yellow markings on the body scales of P. oligochrysus are present as indistinct pale spots or, when prominent, are confined to the upper and lower edges of the scales whereas in P. flavopunctatus they are present as prominent central spots; the pelvic fins are bright yellow in P. oligochrysus versus pale pink in P. flavopunctatus .

Using Gill’s (2004) key to Pseudochromis species, P. oligochrysus falls in the couplet (51) distinguishing P. flavopunctatus from species in the remaining couplets ( P. andamanensis Lubbock 1980 , P. aurulentus Gill & Randall 1998 , P. litus Gill & Randall 1998 , P. marshallensis Schultz 1953 , P. p y l e i Randall & McCosker 1989, and P. reticulatus Gill & Woodland 1992 ). It differs from all these species in having 16 segmented anal-fin rays (versus 11–15).

Remarks. The specific epithet is a combination of the Greek words λɩγό and χρυσος that means “having little gold”, alluding to the scant though distinctive yellow markings of the species. When viewed underwater, the yellow markings around the eye are particularly obvious and distinctive, as are the bright yellow pelvic fins.