Plectranthias lamillai , a new Anthiine fish species ( Perciformes , Serranidae ) from the Juan Fernández Archipelago , Chile *

The fishes of the genus Plectranthias (Serranidae: Anthiinae), are small benthic species that generally occur on rocky bottoms at depths greater than those normally penetrated by scuba divers. None are of commercial importance, and most are poorly represented in museum collections (Randall and Shimizu, 1994). This subfamily include a plethora of brightly coloured species of small to medium size fishes, that inhabit tropical to temperate seas worldwide. Most species feed on zooplankton, ocurr in aggregations and are protogynous hermaphrodites (Anderson et al., 1990). We have not seen published data for Plectranthias. Two groups may be tentatively recognized: a tropical group characterized by 13 branched caudal rays, two predorsal bones, dorsal and anal pterygiophores bisegmental, and scales with one marginal row of alternating large and small pointed cteni (e.g. Anthias Bloch, Holanthias Günther and Pseudanthias Bleeker); and a predominantly temperate group characterized by 15 branched caudal fin rays, three predorsal bones, posterior anal and sometimes also posterior dorsal-fin pterygiophores trisegmental, and scales with two rows of pointed cteni of approximately equal size (e.g. Caesioperca Castelnau, Lepidoperca Regan and Plectranthias Bleeker) (Roberts, 1989). SCI. MAR., 62 (3): 203-209 SCIENTIA MARINA 1998


INTRODUCTION
The fishes of the genus Plectranthias (Serranidae: Anthiinae), are small benthic species that generally occur on rocky bottoms at depths greater than those normally penetrated by scuba divers.None are of commercial importance, and most are poorly represented in museum collections (Randall and Shimizu, 1994).
This subfamily include a plethora of brightly coloured species of small to medium size fishes, that inhabit tropical to temperate seas worldwide.Most species feed on zooplankton, ocurr in aggregations and are protogynous hermaphrodites (Anderson et al., 1990).We have not seen published data for Plectranthias.
Two groups may be tentatively recognized: a tropical group characterized by 13 branched caudal rays, two predorsal bones, dorsal and anal pterygiophores bisegmental, and scales with one marginal row of alternating large and small pointed cteni (e.g.Anthias Bloch, Holanthias Günther and Pseudanthias Bleeker); and a predominantly temperate group characterized by 15 branched caudal fin rays, three predorsal bones, posterior anal and sometimes also posterior dorsal-fin pterygiophores trisegmental, and scales with two rows of pointed cteni of approximately equal size (e.g.Caesioperca Castelnau, Lepidoperca Regan and Plectranthias Bleeker) (Roberts, 1989).Archipelago, Chile* Randall (1980) revised the anthiine fish genus Plectranthias.He placed Sayonara, Isobuna, Xenanthias, Pteranthias, Zalanthias, Serranops, Pelontrus, and Zacallanthias in the synonymy of Plectranthias, and added that this revision must be considered preliminary because of the lack of material of so many of the species and the knowledge that more new species remained to be described.Since Randall's 1980 revision, 14 nominal new species have been described including two species from the southeastern Pacific: P. exsul Heemstra and Anderson, 1983;andP. parini Anderson andRandall, 1991 (Randall, 1996) Field work carried out through November and December 1996 by the Instituto de Zoología, Universidad Austral de Chile (IZUA) at Alejandro Selkirk Island, the westernmost island of the Juan Fernandez Archipelago (about 700 km west of Chile 33º45'S,80º51'W) (Fig. 1), resulted in the collection of one specimen of the genus Plectranthias.This specimen represents a new species, which is described here.

METHODOLOGY
Measurements and counts of body parts are a combination of the methods of Randall (1980), Roberts (1989) and Anderson et al., (1990) except as indicated below.The count of the scales above the lateral line to the origin of the dorsal fin was made in a straight vertical line above the third or fourth lateral-line scale to the base of the first dorsal spine.A small scale is present at the base of this spine; this was counted as one.Gillrakers and pseudobranchial filaments were counted on the left side.Measurements were made with needlepoint dial calipers to the nearest 0.1 mm.Most measurements are presented as percentages of the standard length (SL), but some are given as quotients of head length (HL) or orbital diameter (OD).Osteological data are from radiographs.Formula for configuration of predorsal bones, anterior neural spines, and anterior dorsal pterygiophores follows Ahlstrom et al., (1976).The first vertebra with a haemal spine was considered the first caudal vertebra; the urostylar vertebra, the last.In remarks, data for the holotype of P. parini are followed in parentheses, by those for the paratype, when different.Data for the holotype of P. exsul are followed in parentheses by those for the other material examined, when different.Institutional abbreviations are as listed in Leviton et al., (1985) and Pequeño (1995).
The holotype is deposited in the Museo Nacional de Historia Natural de Chile, under ichthyological catalogue number 7055.

Color of holotype in alcohol
Body and head whitish, fins mostly pale to strawcolored; no distinctive pigmentation remaining on fins.

Coloration of holotype when fresh
Body pale yellowish, with a broad red bar from sixth dorsal-fin spine to base of fifth ray of dorsal fin, extending to anus and above anal fin as a narrow band that widens on the peduncle and then bifurcates over the upper and lower margins of the caudal fin; rest of the caudal fin yellowish.An irregular red blotch on nape and below first three dorsal-fin spines, extending to opercle, subopercle, cheek, snout and front of upper jaw; maxilla yellow; lower jaw reddish.Rim of pupil yellow; iris dark with reddish spots.Pectoral fins orange; pelvic an anal fins whitish.
NEW SERRANID FROM CHILE 207

Etymology
We have pleasure in naming this new species in honor of Prof. Julio Lamilla (Instituto de Zoología "Ernst F. Kilian", Universidad Austral de Chile) in recognition of his contributions to Chilean ichthyology.

Distribution
Plectranthias lamillai is known only from the type locality in the Alejandro Selkirk Island in the eastern South Pacific, about 700 km west of the Valparaíso Bay, Chile at 33º45'S, 80º51'W.

Comments
Plectranthias lamillai has more lateral-line scales (40-41) and more gillrakers (8+20) than any other species in the genus except P. exsul (Heemstra and Anderson, 1983) from Juan Fernández Islands and Nazca Submarine Ridge and P. parini (Anderson and Randall, 1991) from the Salas y Gómez Submarine ridge and Easter Island.P. lamillai is separated easily from P. parini because it has more tubed lateral-line scales (40-41 vs 37-40), more gillrakers (total on first arch 28 vs 26), fewer pseudobranch filaments 24 vs 25 (38), more rows of cheek scales (10 vs 9), and fewer serrae on subopercle 2-6 vs 8-19.The pectoral fin in P. lamillai reaches vertical at the base of the first anal-fin spine, while in P. parini this fin reaches a vertical through the base of the third anal-fin ray (Anderson and Randall, 1991).In P. lamillai the maxilla reaches a vertical through the first quarter of eye, while in P. parini it reaches a vertical through posterior border of eye.In P. lamillai the dorsal and ventral-most procurrent caudal-fin rays are covered by scales (not shown in Figure 2), but naked in P. parini (Anderson and Randall, 1991).
P. lamillai differs from P. exsul in having the maxilla shape more narrow and rounded.Circumpeduncular scales in P. lamillai are 16 vs 18-22 in P. exsul.P. lamillai has the tubes of the anterior lateral-line scales branched while in P. exsul the tubes are simple (Fig. 3).Number of scales in a vertical line from dorsal-fin origin to lateral line 3 (P.lamillai) vs 4 or 5 (5) (P.exsul).In P. exsul the maxilla reaches or almost reaches a vertical through posterior border of orbit while in P. lamillai the maxilla only reaches vertical through first quarter of eye.In P. lamillai the dorsal and ventral-most procurrent caudal-fin rays are covered by scales, naked in P. exsul (Heemstra and Anderson, 1983).The other material examined for P. exsul has more serrae on preopercle 52-57 vs 41-44; more serrae on interopercle 6-7 vs 4 and subopercle 11-13 vs 2-6 and more tubed lateral-line scales (45-48 vs 40-41).
P. lamillai differs from P. exsul and P. parini in colour pattern.Alive P. parini has two broad red bars on body, one below posterior half of spinous portion of dorsal fin and one below posterior half of soft portion of dorsal fin and adjacent to caudal peduncle (Randall 1996).P. exsul has a broad oblique red band below posterior half of soft portion of dorsal fin, narrowing towards posterior end at ventral edge of caudal peduncle (Randall 1996) and P. lamillai has vertical broad red bar from sixth dorsal-fin spine to base of fifth ray, extending to anus and above anal fin as a narrow band that widens on the peduncle and then bifurcates over the upper and lower margins of the caudal fin; rest of the caudal fin yellowish.A red blotch on nape and below first three dorsal-fin spines, extending to opercle, subopercle, cheek, snout and front of upper jaw; maxilla yellow; lower jaw reddish.was partially supported by Deutscher Akademischer Austauschdienst (DAAD), which provided a scholarship for graduate studies of the first author, the Universidad Austral de Chile (Project S-96-04) and National Geographic Society (Grant 5257-96).
Origin of anal fin beneath anterior soft portion of dorsal fin.Second spine of anal fin about 1.6 times length of first anal spine and 1.2 times length of third anal spine.Anal-fin base length 6.8 in SL.Pectoral fin pointed, the middle rays longest, reaching vertical through base of third dorsal soft ray and base of first anal spine.Pectoral fin length 3.5 in SL.Pelvic fin inserted beneath base of pectoral fin, the tip reaching a vertical through base of last dorsal spine, falling close to short of the anus.Pelvic fin length 4.4 in SL.Caudal rays mostly broken.Body depth 3.2 in SL, body width 7.4 in SL and 2.3 in depth.Snout length 4.0 in HL.Head length 2.4 in SL.Orbital diameter 4.4 in HL.Width of maxilla 1.9 in OD.Width of suborbital 4.1 in OD.Upper jaw length 5.5 in SL.Fifth dorsal spine, 2.4 in HL.Second anal spine 2.6 in HL.Length of caudal peduncle 2.5 in HL.Interorbital width 6.0 in HL.Lateral line complete, running parallel to dorsal body contour below dorsal fin, curving to near mid-lateral axis of body on caudal peduncle.The first three tubes in lateral line scales with 2-3 branches (both sides).Scales ctenoid; tubed lateral line scales 40 on left side (41 right side).Circumpeduncular scales 16.Rows of cheek scales 10 (both sides).No scales on lateral aspect of snout, maxilla, premaxilla, dentary, branchiostegal membranes, gular region or mid-dorsal area nearly to upper lip.Interorbital region, preopercle, opercle, subopercle and interopercle scaled.Three scales above lateral line to origin of dorsal fin.Two rows of large scales between the highest arched portion of lateral line and spinosus portion of dorsal fin.

TABLE 1 .
Anderson and Randall (1991))nd counts of Plectranthias lamillai sp.nov., expressed as percentages of standard length.Data on holotypes of P. exsul and P. parini are fromHeemstra and Anderson (1983)andAnderson and Randall (1991)respectively.The asterisk means broken.
NEW SERRANID FROM CHILE 205 FIG. 2. -Holotype of Plectranthias lamillai sp.nov.MNHNC P. 7055, 139.6 mm SL, from Alejandro Selkirk Island 33º45'S, 80º51'W (Juan Fernández Archipelago), Chile.with two rows of small conical teeth extending from near posterior end of bone to about middle of jaws; at middle of each side of lower jaw three robust and incurved canines (two on right side).and nearly obtuse.Origin of dorsal fin above third or fourth lateral line scale.Dorsal fin single and continuous, not divided at base between spinous and soft rayed parts.Dorsal-fin base length 2 in SL. 206 J. RODRIGO-ROJAS and G. PEQUEÑO