Polylepion gilmorei Baldwin, Arcila, Robertson & Tornabene, 2023, new species
Creators: name: Baldwin, Carole C.
name: Arcila, Dahiana
name: Robertson, D. Ross
name: Tornabene, Luke
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Perciformes
Labridae
Polylepion
Polylepion gilmorei

description: Polylepion gilmorei, new species   
urn:lsid:zoobank.org:act: C3EE7A2D-AEA9-46C1-BBEA- A8541F6AC0CA  
Red-barred Wrasse (English), Vieia de Barras Rojas (Spanish), Labre à barre rouge (French)  
Figures 1–3, Supplemental Figures S1–S 2, Tables 1–2, Supplemental Table T1  
 Polylepion species A, Curaçao, Robertson and Van Tassell (2016), https://biogeodb.stri.si.edu/caribbean/en/gallery/ genus/5244.   
 Polylepion species A, Pichincho, Quattrini et al. (2017): fig. 11B.   
 Polylepion sp., Curaçao, Baldwin et al. (2018): fig. 2.   
 Holotype.— USNM 445945, 87.5 mm SL, not a genetic voucher, French Bay, San Salvador, Bahamas Islands, 23857.47  0  N, 74830.20  0  W, Johnson Sea Link-I (JSL-I) submersible, dive # 2028, 367 m, rotenone, C. R. Robins and D. Liberatore, 5 May 1987.   
 Paratypes.— Bahamas: UF 248937, 54.3 mm SL, not a genetic voucher, SE Sandy Pt., San Salvador, Bahamas Islands, JSL-I dive # 1290, 280 m, rotenone, R. G. Gilmore, Jr. and M. Flake, 17 October 1982; USNM 445946, 48.0 mm SL, not a genetic voucher, same collection data as holotype; USNM 445947, 35.8 mm SL, not a genetic voucher, Riding Rock, San Salvador, Bahamas Islands, JSL-I dive # 1294, 282 m, rotenone, C. Donohoe and R. Cook, 19 October 1982; USNM 445948, 41.1 mm SL, not a genetic voucher, Riding Rock, San Salvador, Bahamas Islands, 24802.9  0  N, 74830.35  0  W, JSL-I dive # 2023, 309 m, rotenone, C. R. Robins and M. Adams, 2 May 1987; USNM 445949, 34.4 mm SL, not a genetic voucher, Riding Rock, San Salvador, Bahamas Islands, 24803.5  0  N, 74832.5  0  W, JSL-I dive # 1513, 279 m, rotenone, C. R. Robins and D. Liberatore, 31 October 1983. Curaçao: SIO 22-91, 51.8 mm SL, genetic-voucher specimen number CUR15123, Curaçao, southern Caribbean Sea, west of Substation Curaçao downline, 1284  0  58.8  00  N, 68853  0  56.4  00  W, Curasub submersible, dive #CURASUB 15-20, 250 m, C. Baldwin, B. Brandt, and D. Felder, 21 September 2015; USNM 413995, 114.2 mm SL, genetic-voucher specimen number CUR13087, Curaçao, southern Caribbean Sea, off Substation Curaçao downline, near 1284  0  59.5  00  N, 68853  0  56.8  00  W, Curasub dive #CURASUB13- MISC, no depth recorded, Substation Curaçao staff, 2012– 2013; USNM 435298, 35.7 mm SL, genetic-voucher specimen number CUR15022, Curaçao, southern Caribbean Sea, off Substation Curaçao downline, 1284  0  59.5  00  N, 68853  0  56.8  00  W, Curasub dive #CURASUB15-06, 272 m, C. Baldwin, B. Van Bebber, D. R. Robertson, and C. Castillo, 11 February 2015; USNM 440432, 27.9 mm SL, genetic-voucher specimen number CUR16001, Curaçao, southern Caribbean Sea, east of Substation Curaçao downline, 1284  0  59.5  00  N, 68853  0  56.8  00  W, Curasub dive #CURASUB 16-32, 219 m, C. Baldwin, B. Brandt, D. Pitassy, and T. Devine, 6 October 2016. Dominica: USNM 438664, 54.5 mm SL, genetic-voucher specimen number DOM16013, Saint George Parish, Roseau, Dominica (off Fisheries Dock), 15817  0  40.6  00  N, 61823  0  23.6  00  W, Curasub dive #CURASUB16-02, 262 m, A. Schrier, B. Brandt, and B. Van Bebber, 24 February 2016; USNM 440584, 34.1 mm SL, not a genetic voucher, western coast of Dominica, 15837  0  11  00  N, 61828  0  03  00  W, Curasub dive #CURASUB 16-22, 244 m, B. Hoeksema, A. Schrier, B. Van Bebber, and D. Sipkema, 16 March 2016. Roatan: MUVS- 447, 108 mm SL, genetic-voucher specimen number ROA17024, off Half Moon Bay, Roatan, Idabel submersible, dive #IDABEL 17-05, 305 m, L. Tornabene, R. Manning, and K. Stanley, 29 July 2017; UW 158149, 101 mm SL, genetic-voucher specimen number ROA18106, off Half Moon Bay, Roatan, Idabel dive #IDABEL 18-06, 305 m, R. Robertson, R. Manning, and K. Stanley, 8 June 2018.   
 Other Material (not examined): Cuba: juvenile (no length available), Cayo Rosario, Cuba, JSL-I dive # 3054, 427 m, Rodolfo Claro, Dec. 1997 (illustrated by R. G. Gilmore, Jr.).   
 Diagnosis.— A revised diagnosis of Polylepion is presented after the species description. Polylepion gilmorei, the only species of Polylepion in the Atlantic Ocean, is distinguished from other wrasses by the following combination of characters: dorsal-fin rays usually XI, 11; anal-fin rays usually III, 11; pectoral-fin rays usually ii17; lateral-line complete, 38–44 tubed scales; scales above lateral line 2–4; scales not extending onto bases of dorsal and anal fins; scales on forehead extending anteriorly beyond or nearly to level of anterior nostrils; in life, multiple orange-red bars of pigment on dorsal portion of the trunk against an otherwise whitish background, and a red (adults) or black (juveniles) circular blotch on dorsal portion of caudal-fin base; inhabiting depths of 219– 457 m.   
 Description.— Counts and measurements are summarized in Tables 1 and 2. Counts of holotype are given first, followed by any variation in the 13 paratypes in parentheses. Dorsal-fin rays XI, 11 (one paratype with XII, 10); anal-fin rays III, 11 (one paratype with III, 10); pectoral-fin rays ii17 (one paratype with ii16); pelvic-fin rays I, 5; dorsal unsegmented caudal-fin rays 8 (seven paratypes with 9); dorsal segmented, unbranched caudal-fin rays 2; segmented, branched caudal-fin rays 6 þ 6 (one paratype with 6 þ 5); ventral segmented, unbranched caudal-fin rays 2; ventral unsegmented caudal-fin rays 8 (four paratypes with 9); vertebrae 11 þ 17; lateral-line scales 39, 41 (38–44, too many scales missing in four paratypes to obtain accurate counts); scales above lateral line 3 (2–4, too many scales missing in two paratypes to obtain accurate counts); scales below lateral line 11 (9–12, too many scales missing in six paratypes to obtain accurate counts); predorsal scales 21 (20–25, too many scales missing in eight paratypes to obtain accurate counts); gill rakers 7 þ 10, last two tiny (6–8 þ 9–10, last one to three tiny).   
Body deepest around midbody, tapering posteriorly. Head pointed, profile mostly straight except for convexity between orbits. Scales on trunk not extending onto dorsal- and anal-fin bases. Lateral line continuous, smoothly curved. Head mostly scaled except snout, lips, gular region, and branchiostegals. Scales extending anteriorly on forehead in advance of or nearly to anterior nostrils.  
Posterior end of maxilla reaching vertical through anterior edge of orbit. Upper and lower jaws each with two pairs of large canines anteriorly. Anterior canines in upper jaw of similar size, followed by a row of much smaller canines (7 in holotype) and one moderately large canine at rear corner of jaw. Medial canines of large anterior pair in lower jaw smaller than more lateral ones.  
Dorsal fin continuous, originating just anterior to vertical through base of pectoral fin. Membrane between dorsal- and anal-fin spines deeply incised, membrane forming small flags of tissue at tips of spines. Dorsal and anal fins slightly pointed posteriorly, longest rays not reaching margin of hypural plate in adults. Posterior margin of caudal fin somewhat rounded in juveniles, more truncate in adults. Posterior extent of pelvic fin not reaching anus.  
Adults pale in alcohol with no dark markings on head, trunk, or fins (Fig. 1A). Juveniles similar except with circular blotch of melanophores on dorsal base of caudal fin. In addition to that blotch, smallest juvenile (27.9 mm SL) with six indistinct black bars on trunk, a dark stripe extending from snout to operculum, some dark pigment on pectoral-fin base, and dark spots present on lower caudal-fin base. A 35.7 mm juvenile with remnants of these dark markings.  
In life (Figs. 1B, 2C), adults with six orange-red bars of pigment on dorsal portion of trunk, anteriormost bars terminating ventrally slightly below midbody, last bar extending from dorsal to ventral margins of caudal peduncle, bar much paler ventrally. Large red circular blotch on dorsal base of caudal fin, irregular and paler red bar below this blotch. Upper half of head red, eye mostly yellow. Indistinct stripe of red pigment extending along center of entire dorsal fin, stripe narrow on spinous dorsal fin, usually broader on soft dorsal fin. Uppermost and lowermost caudal-fin rays red, forming the margins of a broad, indistinct bar of red pigment on central area of caudal fin. Oblong blotch or streak of red pigment on pectoral-fin base. Gilmore’s color-pencil sketch of the holotype (Fig. 1B) shows a broad red stripe centrally on soft portion of anal fin, but this pigment not apparent in photographs of freshly caught specimens, in which the extent of red pigmentation also varies on the dorsal fin (Fig. 2).  
 * Polylepion cruentum from northern Peru was reported to have XI, 12 dorsal-fin rays and III, 13 anal-fin rays (Britzke et al., 2021), all others with counts of XI, 11 and III, 12; P. gilmore i, USNM 445948, with XII, 10 dorsal-fin rays, all others with XI, 11; holotype of P. ruSSelli (Gomon and Randall) and one paratype of P. gilmorei, USNM 445948, with III, 10 anal-fin rays, other specimens with III, 11; P. gilmorei, USNM 445946, with ii, 16 pectoral-fin rays on both sides, all others with 17. Indian Ocean specimen of P. ruSSelli with scales on forehead extending to anterior nostril (Béarez et al., 2013), Pacific specimens with scales extending only to anterior extent of orbit.   
Juveniles (Fig. 2A, B) with the six orange-red trunk bars extending further ventrally than in adults, bars containing some melanophores mixed in with the red chromatophores in smallest juveniles. Spot on upper base of caudal fin relatively larger than in adults, black or a black/red mix and broadly rimmed with iridescent white. Head pigment similar to that of adults except red on upper portion of head pale, setting off a distinctive narrow red stripe running from tips of jaws through center of eye to upper rear corner of operculum. Other fin pigment similar to that of adults.  
 Distribution and habitat.— Known from specimens collected in the Bahamas, Cuba, Curaçao, Dominica, and Roatan; from imagery taken by the ROV Kraken aboard the NOAA R/V Nancy Foster on 28 September 2011 at 300 m on the Pourtales Terrace, south of the Florida Keys (Andrew David, NOAA, pers. comm.); and from imagery taken at 240–457 m by the ROV Deep Discover tethered to the camera sled Seirios deployed from the NOAA Ship Okeanos Explorer on seamounts east and west of Puerto Rico (Quattrini et al., 2017: fig. 11B). The Pourtales Terrace image is reproduced here in Supplemental Fig. 1A (see Data Accessibility). Polylepion gilmorei inhabits depths of 219–457 m and associates with hard substrates, including rocky ledges and patches of dead corals or rocks lying on silty sand bottoms (Supplemental Fig. 1B [see Data Accessibility]; in situ video from Roatan is available from the Zenodo digital repository: https://doi.org/ 10.5281/zenodo.7304806).   
 Etymology.— Named in honor of Richard Grant Gilmore, Jr., in recognition of the contributions he has made to our knowledge of the western Atlantic and Caribbean deep-reef fish fauna, including the first discovery of the new Polylepion.   
 Comparisons.— Counts and measurements of the species of Polylepion are summarized in Tables 1 and 2. Currently the only known species of the genus in the Atlantic Ocean, P. gilmorei differs from P. cruentum in having fewer anal-fin rays (III, 10–11, almost always 11, vs. III, 12–13, usually 12 in P. cruentum). It differs from P. russelli in having fewer pectoral-fin rays (ii, 16–17, usually 17, vs. ii, 18–19 in P. russelli) and fewer scales above the lateral line (2–4 vs. 5 in P. russelli). Polylepion gilmorei differs from both congeners in having fewer lateral-line scales (38–44 vs. 48–52 in P. russelli and 49– 53 in P. cruentum) and scales below the lateral line (9–12 vs. 17–18 in P. russelli and 16–18 in P. cruentum). The new species further differs from its congeners in color pattern, especially in having multiple red bars of pigment on the dorsal portion of the trunk against an otherwise whitish background (vs. color pattern of trunk variable in P. cruentum and P. russelli, usually with at least some yellow stripes on the trunk against a pinkish background in small specimens, never with distinct red bars). The largest specimen of P. gilmorei is 114 mm SL, whereas that of P. cruentum is 199 mm SL and P. russelli 313 mm SL, which could indicate that P. gilmorei is a smaller species than its congeners.   
 Relationships.— (Fig. 3) Early morphological studies noted the resemblance among Bodianus, Decodon, and Polylepion and suggested a close relationship between species of Polylepion and Decodon (Gomon, 1997). The results of our phylogenomic analysis are congruent with those of Aiello et al. (2017), Hughes et al. (2022), and Larouche et al. (2022) in strongly supporting a sister-group relationship between the deep-reef genera Polylepion and Decodon (bootstrap support ¼ 97%) and with those studies and Santini et al. (2016) in revealing that Bodianus includes species formerly classified in the genera Clepticus and Semicossyphus (Supplemental Fig. S2; see Data Accessibility). Unlike the phylogeny of Aiello et al. (2017), in which Decodon and Polylepion were embedded in the Bodianus clade, our results agree with those of Hughes et al. (2022) and Larouche et al. (2022) in resolving Decodon and Polylepion as distinct from Bodianus. Further taxonomic study of Bodianus is needed to resolve the species composition of that genus.   
 Our results provide the first molecular evidence for the monophyly of the genus Polylepion (bootstrap support ¼ 100%) and support the recognition of P. gilmorei as a distinct species. The phylogeny further suggests that the eastern Pacific P. cruentum is sister to the clade comprising the western Atlantic P. gilmorei and Indo-Central-West Pacific P. russelli.   
 Biogeography.— One possible biogeographic scenario for the current distribution of Polylepion based on the time-calibrated phylogeny (Fig. 3) involves an initial split of the eastern Pacific population approximately 10 mya, with westward migration that ultimately isolated P. russelli. That occurred at about the same time as the separation of the other Neotropical genus of deep-reef wrasses, Decodon, into eastern Pacific and western Atlantic populations, suggesting a linkage of these events in both genera to shoaling of the central American isthmus prior to its final closure ~ 2 mya (Lessios, 2008; O’Dea et al., 2016). Since P. russelli is known as far west as Réunion Island in the southwest Indian Ocean, further westward migration around the tip of South Africa approximately 6 mya could have led to the establishment of an isolated Atlantic population. Colonization from the Indian Ocean directly into the western Atlantic has been hypothesized for some shallow-reef fishes, including Centropyge (Bowen et al., 2006, and references therein), which, like Polylepion, is not known from the tropical eastern Atlantic. Gordon (2003) noted that dispersal directly from the Indian Ocean into the western Atlantic could occur via the surfaceflowing South Equatorial Current, which runs below the equator from the eastern Atlantic to Brazil. However, given that the global tropical deep-reef fish fauna is poorly known, additional species of Polylepion may be discovered, and other biogeographic scenarios are possible.   
  Revised diagnosis of Polylepion. —  Gomon (1977) proposed the generic name Polylepion (‘‘many small scales’’) in reference to large number of lateral-line scales (48–53) relative to those in the closely related genera Bodianus (30– 48), Decodon (26–30), and Semicossyphus (42–45), although he noted that Pimelometopon has 53–57 (Gomon, 1977: table 1). Polylepion gilmorei has fewer lateral-line scales (38–44) than its congeners, a count that overlaps those of Bodianus and ‘‘ Semicossyphus. ’’ Discovery of the new Atlantic species necessitates minor changes in the diagnosis of Polylepion, and the new diagnosis follows with Gomon’s (1977) diagnostic characters given in parentheses if different: dorsal-fin rays XI, 10–12, usually 11 (XI, 11); anal-fin rays III, 10–13, usually 11 or 12 (III, 11–12); pectoral-fin rays ii, 16–19, usually 17 or 18 (ii, 17–19); lateral-line scales 38–53 (48–52); scales above lateral line 2–5 (2 1 / 2 –5); scales below lateral line 9–18 (16–19, usually 17 or 18); predorsal scales approximately 20–32 (25–32); scales on forehead reaching forward to a vertical between anterior edge of orbit and one anterior to anterior nostrils; color in alcohol pale with dusky spot on dorsal base of caudal fin in juveniles. Since neither P. gilmorei nor P. russelli has black interspinal membranes in the anterior portion of the dorsal fin, that character in Gomon’s (1977) diagnosis is removed from the revised diagnosis.
description: Published as part of Baldwin, Carole C., Arcila, Dahiana, Robertson, D. Ross & Tornabene, Luke, 2023, Description of the First Species of Polylepion (Teleostei: Labridae) from the Atlantic Ocean with Analysis of Evolutionary Relationships of the New Species, pp. 181-190 in Ichthyology & Herpetology 111 (2) on pages 183-188, DOI: 10.1643/i2022075, http://zenodo.org/record/13744502