Plectranthias flammeus, Williams, Jeffrey T., Delrieu-Trottin, Erwan & Planes, Serge, 2013

Williams, Jeffrey T., Delrieu-Trottin, Erwan & Planes, Serge, 2013, Two new fish species of the subfamily Anthiinae (Perciformes, Serranidae) from the Marquesas, Zootaxa 3647 (1), pp. 167-180 : 170-174

Plectranthias flammeus , new species

Common Name: Flame Perchlet ( Fig. 2 )

Plectranthias sp. Bacchet et al. (2006: 185), Marquesas.

Holotype. USNM 409013; 21 mm SL; French Polynesia, Marquesas, Nuku Hiva , Uea, west coast, on rock wall dropping to rubble and sand slope; field number MARQ-2011-02; tissue voucher number MARQ-013; decimal latitude -8.9284, decimal longitude -140.2254; depth 20–40 m; collected with rotenone and hand nets; collectors S. Planes, P. Sasal & J. Mourier; 26 Oct. 2011; vessel “Braveheart.”

Paratypes. Collected with holotype: MNHN 2013-0001 (ex USNM 409014), 18 mm SL, tissue voucher number MARQ-014; USNM 409019, 12 mm SL, tissue voucher number MARQ-019. USNM 409425; 24 mm SL; French Polynesia, Marquesas, Fatu Hiva , Mahitoa point, on southwest side of island, on outer rock wall sloping to flat rubble shelf at about 27 m with spear fishing on the shallower part of wall; field number MARQ- 2011-30; tissue voucher number MARQ-425; decimal latitude -10.5346, decimal longitude -138.6824; depth 7–27 m; collected with rotenone and hand nets; collectors J. Williams, S. Planes, E. Delrieu-Trottin, P. Sasal & J. Mourier; 9 Nov. 2011; vessel “Braveheart.”

Diagnosis. Dorsal rays X, 14–15; dorsal spines 1–6 with fleshy white tabs at tips of spines, longest tab on spine 4; pectoral rays 14, all unbranched; LL incomplete with 16–17 tubed scales; oblique rows of scales on cheek 4; scales on top of head extending anteriorly to vertical from posterior margin of orbit; no scales on maxilla; preopercle with 8–10 small spines along posterior margin and 2 antrorse spines on ventral margin; interopercle with 2–3 spines; subopercle with 1 spine; fourth dorsal spine longest; broad, fiery red-orange streak across lower cheek; head and body with irregularly spaced maroon-ringed yellow blotches on a white background; eye-sized, brilliant white saddle on top of caudal peduncle posterior to base of dorsal fin.

Description. Dorsal rays X, 14 (14–15); dorsal spines 1–6 with fleshy white tabs extending beyond tips of spines, longest tab on spine 4; anal rays III, 7, second spine longest and stoutest; pectoral rays 14, all unbranched, middle rays longest and reaching to about base of third anal spine; pelvic fin I, 5; caudal fin with 4 dorsal and 4 ventral procurrent rays, 2 dorsal and 2 ventral unbranched rays, 7 + 6 branched rays; LL incomplete with 17 (16) tubed scales, pitted scales 10 (9); vertical scale rows 28; scales above LL to origin of dorsal fin 2; scales above LL to base of middle dorsal spine 1; scales below LL to origin of anal fin 10; diagonal rows of scales on cheek 4; scales on top of head extending anteriorly to vertical from posterior margin of orbit where single row of mid-dorsal scales continues anteriorly almost to mid-point between eyes and a single row of small scales continues laterally along posterior border of each eye to top of eyes, forming small pair of rounded scaleless areas on top of head between orbits; circumpeduncular scales 14 (16); no scales on chin, maxilla or snout; gill rakers 6 + 13 (holotype with 1 + 8 developed rakers; paratypes with 1 + 6 to 1 + 9 developed rakers); pseudobranchial filaments 9; vertebrae 10 + 16 = 26; supraneurals 2; supraneural-dorsal ray-pterygiophore-neural spine interdigitation pattern 0/0/2/1+1/1/1/1/1/1/ 2/1/1+1/1+1/1/1+1/1/1+1/1+1/ (one paratype with 0/0/2/1+1/1/1/1/1/1/2/1/1+1/1+1/1/1+1/1/1+1/1+1/1).

Diminutive species 19.7 mm SL (11.5–23.4 mm); body depth 2.7 (2.7–2.9) in SL; head length 2.2 (2.1–2.5) in SL; snout length 4.9 (3.9–4.8) in HL; orbit diameter 3.7 (3.4–4.2) in HL; bony interorbital width 9.8 (7.9–9.8) in HL, upper jaw length 2.3 (2.0–2.4) in HL; caudal peduncle length 2.4 (2.1–3.1) in HL; caudal peduncle least depth 2.9 (2.8–3.7) in HL; snout to D origin length 2.4 (2.1–2.5) in SL; snout to A origin length 1.4 in SL; snout to pelvic origin length 1.1 (1.0–1.2) in HL; length of longest (4th) D spine 2.5 (1.9–2.9) in HL; length of longest A spine 1.6 (1.0–1.8) in HL; pectoral-fin length 1.1 (1.1–1.7) in HL; pelvic-spine length 2.8 (2.3–2.9) in HL; longest pelvic-ray length 1.6 (1.0–1.8) in HL.

Mouth large, slightly oblique, posterior margin of maxilla reaching almost to a vertical at posterior edge of eye; maxilla expanded posteriorly, with long, low, lateral ridge running parallel to dorsal margin; mouth terminal (lower jaw may protrude slightly); upper jaw with one fixed, short stout outer canine on either side of symphysis flanked internally by villiform band with 4–6 rows of depressible, smaller, sharp-tipped teeth, with inner rows becoming progressively longer, innermost row with largest teeth; lower jaw with outer row of fixed, short stout canines at symphysis followed by smaller, depressible, sharp-tipped conical teeth in a villiform band of about 3–4 rows, teeth becoming progressively longer on inner rows, teeth of inner row about 3 times longer than teeth of middle rows, villiform band narrows to 1 row toward sides; vomer with roughly V-shaped band of 3–5 rows of sharp-tipped conical teeth, largest teeth in innermost row; palatines with 2–4 rows of small, sharp-tipped conical teeth; tongue small, narrow, pointed, without teeth.

Opercle with 3 prominent flat spines, middle spine slightly longer; preopercle with 11 (8–11) small spines along posterior margin and 2 antrorse spines on ventral margin; interopercle with 2 left–3 right (1–3 on each side) spines; subopercle with 1 spine. Anterior nostrils positioned at middle of snout, each with small rounded flap rising from anterior rim; posterior nostril an elliptical opening at anterior border of orbit.

Scales ctenoid; lateral line broadly arched over pectoral fin following body contour, tubed portion ending beneath middle of soft dorsal, pitted scales on posterior third of body extend midlaterally to caudal-fin base; fins have at most some small scales scattered along base of fins.

Dorsal spines 1–6 with fleshy white tabs, fourth dorsal spine longest and bearing longest fleshy white tab extending beyond tip; dorsal fin deeply incised before first segmented-fin rays; anal fin rounded with segmented ray 5–6 longest; caudal fin truncate to slightly rounded; pectoral fin lanceolate with middle rays longest and reaching vertical from anal-fin element 3–5; pelvic fins short, not reaching anus.

Color in life (based on photos of the freshly collected types and the underwater photo published by Bacchet et al. 2006). Head and body with numerous variously sized yellow blotches outlined with red or maroon border (red areas mixed with scattered melanophores); snout and lips with white mid-line stripe flanked on each side by a sequence of narrow red, yellow, then red stripes extending from eye across lips; remainder of chin, lower lip, chest and belly white; broad, brilliant red and orange streak extending from upper lip along dorsal half of maxilla and across cheek to angle of preopercle; top of head with scales broadly outlined with reddish maroon and small yellow blotches, pair of small, brilliant white spots on either side of head at middle of nape; red, orange and yellow zigzagging stripe from posteroventral border of eye across middle of cheek, gill cover, pectoral-fin base and terminating in pupil-sized red blotch on bases of middle pectoral-fin rays; pelvic fins white with small red spot at base; pale yellow blotch basally on dorsal spines 1–5 and extending onto body over 1–2 scale rows, smaller pale yellow blotch at base of spines 6–8, third pale blotch basally on dorsal spines 9–10 and first segmented ray; Spinous dorsal with small red-orange-yellow spots on middle of first two spines, at base of 5th and 8th spines and a few smaller spots scattered across middle of fin, white fleshy tabs on tips spines 1–6; second dorsal translucent with faint band of orange across basal quarter of fin; brilliant white saddle on caudal peduncle posterior to dorsal fin; caudal fin translucent with pair of pupil-sized red and black spots positioned basally on caudal rays just dorsal and ventral to midline of caudal fin; anal fin red blotch at base of spines 1–3, yellow-orange spots basally on segmented rays 1–2 and another on rays 5–7; pectoral fin translucent with rays outlined in red; iris of eye with alternating red and yellow blotches.

Color in alcohol similar to pattern in life with red areas marked by scattered melanophores and yellow areas pale.

Etymology. The specific epithet flammeus is from the Latin flammeus , meaning fiery, and refers to the brilliant red and yellow diagonal streak across the lower cheek and the red-yellow-orange blotches on the body. The name is treated as a noun in apposition. The common name, Flame Perchlet, refers to the distinctive flame-like markings on the head and body.

Remarks. Plectranthias flammeus is distinguished from other members of the genus except P. i n e r m i s, P. gardineri (Regan, 1908) , P. nanus , P. longimanus (Weber, 1913) and P. winniensis , by having unbranched pectoralfin rays and an incomplete LL with fewer than 25 tubed scales. It differs from P. i n e r m i s ( Fig. 3 ) and P. g a rd i n e r i (Randall & Shimizu 1994) in color and in having two antrorse spines on the lower margin of the preopercle (versus none or one, respectively). The color pattern ( Fig. 4 ) of P. flammeus readily distinguishes it from the barred color patterns of P. longimanus ( Fig. 5 ) and P. nanus ( Fig. 6 ) as well as the generally uniform yellow and pinkish body of P. winniensis ( Fig. 7 ). Its pectoral-fin ray count of 14 overlaps with P. nanus (14–16), but differs from P. longimanus (12–13) and P. winniensis (16–18). Plectranthias flammeus has a pair of small dark oblong spots (red with black centers in life; Fig. 4 ) on the bases of the middle rays of the caudal fin, whereas P. nanus has a dark, narrow vertical bar (red and black in life; Fig. 6 ) separated from the body by a pale area.

Plectranthias flammeus is known only from the Marquesas Islands, where it has been found at the islands of Nuku Hiva and Fatu Hiva . It likely occurs throughout the Marquesas Islands, but its secretive nature and small size make it difficult to locate.

Genetic information and/or tissue samples are scarce for members of the genus Plectranthias , with COI sequences available for only five species of the genus ( Table 1). Results from our molecular analysis reveal a wellsupported genetic divergence between the P. flammeus lineage and its congeners ( Fig. 8 ).

Phil Heemstra (pers. comm. 2013) informs us that the Plectranthias winniensis from the type locality (Western Indian Ocean) have a color pattern character distinct from our French Polynesia specimen. Although it is probable that the French Polynesia population represents an undescribed species, we retain the current name for our central Pacific form until further study of the complex can be completed.

In Randall’s original description of Plectranthias nanus , he noted that his single specimen of P. nanus from the Marquesas has only 16 lateral-line scales, while specimens from other localities have 18–22. The specimen ( Fig. 6 ) we collected in the Marquesas has 17 lateral-line scales. The COI sequences for P. nanus from the Marquesas and other localities (Gambier Archipelago and Moorea, French Polynesia) group together in a single lineage ( Fig. 8 ). In the absence of any other distinguishing characters, we expand the range for the number of tubed lateral-line scales to 16–22 for P. nanus and interpret this character as being highly variable for the species. We note that this level of variation (seven rays) is highly unusual for a species of Plectranthias . Most species have a strongly modal pectoral-fin ray count with a range of variation of only two or three rays.

Figures

FIGURE 2. Plectranthias flammeus, holotype, USNM 409013, 21 mm SL, freshly collected at Nuku Hiva, Marquesas, French Polynesia, photographed by J. T. Williams.

FIGURE 3. Plectranthias inermis, USNM 391341, about 30 mm SL, freshly collected from 27 – 30 m depth at Verde Island, Philippines, photographed by J. T. Williams.

FIGURE 4. Plectranthias flammeus, paratype, USNM 409025, 24 mm SL, freshly collected at Fatu Hiva Island, Marquesas, French Polynesia, exhibiting the white saddle on the peduncle and small spots at base of caudal fin, photographed by J. T. Williams.

FIGURE 5. Plectranthias longimanus, 14 mm SL, freshly collected from 25 – 37 m depth about 20 miles west of Busuanga Island, Palawan Province, Philippines (field number BUS 03 - 39), photographed by J. T. Williams.

FIGURE 6. Plectranthias nanus, USNM 409250, 27 mm SL, freshly collected from 15 - 30 m depth at Motu One Island, Marquesas, French Polynesia, photographed by J. T. Williams.

FIGURE 7. Plectranthias winniensis, USNM 400675, 16 mm SL, freshly collected from 25 – 31 m depth at Gambier Archipelago, French Polynesia, photographed by J. T. Williams.

FIGURE 8. Neighbor-Joining tree based on K 2 P model of sequence evolution (with 1,000 bootstrap replicates) for available members of the genus Plectranthias.