Plectranthias klausewitzi n. sp. (Teleostei, Perciformes, Serranidae), a new anthiine fish from the deep waters of the southern Red Sea

aqua, International Journal of Ichthyology Plectranthias klausewitzi n. sp. (Teleostei, Perciformes, Serranidae), a new anthiine fish from the deep waters of the southern Red Sea Uwe Zajonz Senckenberg Research Institute and Natural History Museum, Ichthyology Section, Senckenberganlage 25, D 60325 Frankfurt am Main, Germany. E-mail: uzajonz@senckenberg.de Received: 05 July 06 Accepted: 25 July 06 Abstract A new deep-water serranid, Plectranthias klausewitzi, is described from seven specimens, dredged in deep waters of the southern Red Sea. The new species differs from its congeners by the following combination of characters: soft dorsal-fin rays 14-15; pectoral-fin rays 14-15, branched except the uppermost; lateral line complete, tubed scales 29; oblique rows of scales on cheek 7-8; no scales on maxilla and ventral aspects of head; posterior preopercular margin serrate, ventral margin without conspicuous spines; third dorsal spine longest; 9-10 oblique dark bars on dorsal half of body, fused mediolaterally, two dark spots on caudal fin. This is the first record of a deep-dwelling species of the genus Plectranthias from the Red Sea. Zusammenfassung Ein neuer Tiefenwasser-Sägebarsch, Plectranthias klausewitzi, wird beschrieben, basierend auf sieben Exemplaren, die im Tiefenwasser des südlichen Roten Meeres gedredscht wurden. Die neue Art unterscheidet sich von den anderen Arten der Gattung durch folgende Merkmalskombination: 14-15 dorsale Weichstrahlen; 14-15 Brustflossenstrahlen, bis auf die obersten alle gespalten; Seitenlinie vollständig, mit 29 Seitenlinienschuppen; 7-8 diagonale Schuppenreihen auf der Wange; keine Schuppen auf dem Prämaxillare und der Kopfunterseite; hinterer Präoperkularrand gesägt, unterer Rand ohne deutliche Stacheln; dritter Rückenstachel am längsten; 9-10 schräge, dunkle Riegel auf der Körperoberseite, verbunden auf Höhe der Mittellinie; zwei dunkle Flecken auf der Schwanzflosse. Dies ist der erste Nachweis einer Tiefenwasserart der Gattung Plectranthias aus dem Roten Meer. Résumé Une nouveau Serranidé benthique, Plectranthias klausewitzi est décrit sur base de sept spécimens, dragués dans les eaux profondes du sud de la Mer Rouge. La nouvelle espèce se distingue de ses congénères par la combinaison des caractéristique suivantes: 14-15 rayons mous à la dorsale; 14-15 rayons à la pectorale, ramifiés à l exception du plus haut; ligne latérale complète, 29 écailles canaliculées; 7-8 rangées obliques d écailles sur la joue; pas d écailles dans les régions maxillaires et ventrale de la tête; marge préoperculaire postérieure dentelée, marge ventrale sans épines notable; la troisième épine dorsale est la plus longue; 9-10 barres obliques sur la moitié dorsale du corps, se fondant dans la région médio-latérale, deux taches foncées sur la caudale. Il s agit ici de la première occurrence d une espèce benthique du genre Pleactranthias en Mer Rouge. Sommario Un nuovo serranide di profondità, Plectranthias klausewitzi, è descritto sulla base di sette esemplari, pescati in acque profonde nel Mar Rosso meridionale. La nuova specie differisce dai congeneri per la seguente combinazione di caratteri: raggi molli dorsali 14-15; raggi pettorali 14-15, ramificati tranne il primo più in alto; linea laterale completa, con 29 scaglie; file di scaglie oblique sulla guancia 7-8; nessuna scaglia sulla mascella e sulla faccia ventrale del capo; margine preopercolare posteriore seghettato, margine ventrale senza spine evidenti; terza spina dorsale più lunga; 9-10 barre scure oblique sulla metà dorsale del corpo, fuse mediolateralmente, due macchie scure sulla pinna caudale. Rappresenta la prima segnalazione di una specie del genere Plectranthias che abita i mari profondi del Mar Rosso. INTRODUCTION During research cruise M5 in 1987 (Türkay 1996) the R.V. Meteor made one haul with a hard-bottom dredge at depths of 228-235 m in the Strait of Perim (Bab al-mandab), a narrow, shallow passage with a maximum depth of about 300 m connecting the basins of the main Red Sea and the Gulf of Aden (Fig.1). Besides 11 scorpaenid specimens belonging to the genera Neomerinthe Fowler, 1935, Scorpaenopsis Heckel, 1837, and Scorpaenodes Bleeker, 1851, seven specimens of the anthiine genus Plectranthias Bleeker, 1873, were caught. Ten species of the genus have been reported to date from the Western Indian Ocean (Heemstra 1996; Randall 1980, 1994, 1996), four of which 19 aqua vol. 12 no. 1-2006

Plectranthias klausewitzi (Serranidae), a new anthiine fish from the deep Red Sea Fig. 1. Map showing the geographical position of the collecting site. represent deep-dwelling species. Based on two specimens trawled at depths of 190-290 m off south-west Socotra, Xenanthias intermedius (Kotthaus, 1973) was described. In the same publication Kotthaus also recorded Pelontrus morgansi Smith, 1961, from depths of 208-267 m, north of Mombassa, at a location not far from the type locality at 73 m off Lamu, Kenya. Randall (1980) subsequently placed both species in Plectranthias. In the same publication P. bauchotae Randall, 1980, and P. maugei Randall, 1980 were described from Madagascar from depths of 140-180 m and 250 m. From the Red Sea only two wide-ranging, shallow water species, P. winniensis (Tyler, 1966) and P. cf. nanus Randall, 1980 have been recorded so far (Randall 1980). Neither of the present specimens correspond with the deep-dwelling congeners from the area nor with any other Plectranthias species known to date. MATERIALS AND METHODS Methods for counting and measuring followed those of Randall (1980). Meristic and morphometric data are given as values for the holotype, followed by the value ranges for the paratypes in parentheses. Where counts were recorded bilaterally, both values or their ranges are separated by a slash, the first one representing the count taken on the left side of the body. Proportional measurements given in the text are expressed as ratios. In addition, 26 proportional measurements are tabulated as percentages of the standard length (Table I). Osteological details were determined from X- rays. Vertebral counts include the urostylar centrum. Specimens of Plectranthias intermedius (Kotthaus, 1973) and P. morgansi (Smith, 1961) were studied at the Zoological Museum of the University of Hamburg, Germany. Comparisons with other Plectranthias species are based primarily on data provided by Randall (1980, 1996), Heemstra & Randall (1986) and Heemstra (1996). Additional information on the distribution ranges of certain species was obtained from FishBase (Froese & Pauly 2006). Institutional acronyms follow Leviton et al. (1985). The abbreviation SL is used for standard length. Abbreviations: IIO(E) International Indian Ocean Expedition; IOES International Indian Ocean Expedition Sample; SAIAB South African Institute of Aquatic Biology; SL Standard Length; SMF Senckenberg Museum Frankfurt; ZMH Zoological Museum Hamburg. aqua vol. 12 no. 1-2006 20

Plectranthias klausewitzi n. sp. (Figs. 2, 3) Holotype: SMF 29279 (44.9 mm SL, female, eggbearing); southern Red Sea, Strait of Perim, northwest of Perim Island, 12 43.7 N 43 15.0 E, 228-235 m, R.V. Meteor cruise M5, station 230, hard-bottom dredge with a 1 cm mesh net, 5 March 1987. Paratypes: SMF 29294, 5 (54.4 33.5 mm SL), collected with the holotype; SAIAB 65098, 1 (39.4 mm SL), collected with the holotype. Diagnosis: Soft dorsal-fin rays 14 (14-15, mostly 14); pectoral-fin rays 15 (14-15, mostly 15), branched or double-branched except the uppermost; lateral line complete, the tubed scales 29; oblique rows of scales on cheek 8 (7-8); scales on interorbit reaching almost to posterior nostril; no scales on maxilla and ventral aspects of head; posterior preopercular margin serrate, the ventral margin smooth, usually without conspicuous spines; margins of subopercle and interopercle smooth; gill rakers 5 + 12 (4-5 + 11-13); body depth 3.0 (2.7-3.1) in SL; third dorsal spine longest, 1.9 (1.9-2.3) in head; preserved colour pale with nine or 10 oblique dark bars, a faint spot anteriorly on the ventral and the dorsal half of the caudal fin. Description: Dorsal-fin rays X,14 (14-15, mostly 14); anal-fin rays III,7; all dorsal and anal soft rays branched, double-split with increasing size, the last a double-ray, split to base; pectoral fin rays 15/15 (14-15/14-15, mostly 15 on both sides), all rays branched except the uppermost, lowermost 6-8 rays double-branched; pelvic fin rays I, 5; caudal fin with 16 (15-17) branched segmented rays, 2 (1-3) simple segmented rays, and 10 (8-10) pro-current rays; lateral line complete, tubed scales 29; scales above lateral line to origin of dorsal fin 2.5 (2.5-3); scales below lateral line to origin of anal fin 9 (8-9.5); circumpeduncular scales 13 (11-13); oblique rows of scales on cheek 8 (7-8); gill rakers 5 + 12 (4-5 + 11-13), 1+6 developed in holotype; pseudobranchial filaments 13 (13-14), recorded from the three largest specimens; branchiostegal rays 7; vertebrae 26 (10 precaudal + 16 caudal); supraneural (predorsal) bones 3, their arrangement with neural spines and dorsal pterygiophores as follows: 0/0 + 0/2/1 + 1/1/1/1/, where 0 is a supraneural bone, / a neural spine, and numerals are the number of dorsal spines supported by each pterygiophore (Ahlstrom et al. 1976). Body moderately deep, the depth 3.0 (2.7-3.1) in SL, and compressed, the width 2.1 (1.9-2.1) in depth; head fairly short, 2.4 (2.2-2.3) in SL; pectoral fin moderately long and pointed, 3.3 (2.9-3.7) in SL, the terminal portions of the rays broken off in most specimens; pelvic fin 4.5 (4.0-4.3) in SL, the segmented rays 2-3 longest, fin length relative to the position of anus variable, about half a pupil diameter short in the holotype and varying Fig. 2. Plectranthias klausewitzi n. sp.; holotype (SMF 29279), 44.9 mm SL. Drawing of habitus in lateral view. Drawing by G. Eder. 21 aqua vol. 12 no. 1-2006

Plectranthias klausewitzi (Serranidae), a new anthiine fish from the deep Red Sea between 0-1 pupil diameter in falling short of reaching the anus in the paratypes; caudal fin either emarginate or subtruncate, the definite shape unknown because the terminal portions are damaged in all specimens; caudal peduncle length 2.6 (2.1-2.9) in head, its minimum depth 3.1 (3.2-3.3) in head (Fig. 2). Head blunt, the snout short and convex, 4.0 (4.1-5.5) in head; eyes relatively large, 3.0 (2.8-3.4) in head; interorbital space narrow and flat, its minimum bony width 10.2 (10.3-12.4) in head. Occiput slightly convex; occiput and nape covered with ctenoid scales decreasing in size anteriorly. Mouth of moderate size, the maxilla reaching to between verticals at the centre and the rear edge of the eye lens; the upper jaw length 2.4 (2.1-2.4) in head; mouth nearly terminal, the lower jaw slightly exceeding upper jaw, the gape forming an angle of about 30 to horizontal axis of body; premaxilla protrusible; a small splint-like supramaxilla present; upper jaw with a band of small villiform teeth, arranged anteriorly in seven or eight irregular series as broad patches, narrowing posteriorly along the side of maxilla, ending in two to three rows; three to four teeth in inner row of the front patches enlarged, caniniform and inwardly depressible; teeth of the outermost row along the sides of the jaws larger than the inner rows, progressively larger medially in the front patches, a large incurved canine in the outer row of the frontal patches on each side, a second, slightly smaller canine close-set to it in some specimens, the following teeth immediately adjacent to symphysis smaller and slender; the front tooth patches separated by a narrow toothless area at symphysis; the distance between the large canines about equal to one-third orbit diameter; dentary with bands of small, conical teeth in two rows on its posterior half (those on the inner row larger) reaching as far as one or two close-set, recurved canines; bands then expanding anteriorly to four to five rows towards a narrow, toothless symphyseal gap; the large canines taller than in upper jaw, the gap between equal and two-thirds to three-quarters of orbit diameter; a chevron-shaped band of small conical teeth in two to three rows on vomer; a narrow band of small conical teeth in three irregular rows on palatines. Tongue and pterygoids edentate; tongue short, slender and triangular, covered with cutaneous papillae, the pointed tip slightly rounded. Longest gill raker on first gill arch at angle, though first on lower arch of about equal length in several specimens, its length in most specimens slightly smaller than longest gill filament and less than one-third orbit diameter. Opercle with three flat spines, the middle one largest and terminating most posteriorly, curved slightly upwards and closer to lower than to upper spine, borne anteriorly by an elongated strong ossification of the opercle; lower spine acute and sharp; upper spine anteriormost, blunt and poorly ossified, pointing upwards, its dorsal margin fused to the well-developed opercular flap; posterior margin of preopercle serrate, the serrae 21/22 in holotype, varying from 17/17 in the smallest paratype to 26/25 in the largest one; the corner often with irregular indentations; the ventral margin without conspicuous antrorse or retrorse spines, though one (two on one side in one specimen) minute, forward pointing tip present on one or both sides in three of seven specimens (1/1 in holotype) (Fig. 3). Nostrils situated in front of the eyes on a horizontal line drawn through the upper edge of the eye lens, the anterior tubular, with a progressively expanding, cutaneous opening, its posterior margin distinctly higher; the rear nostril situated slightly posterodorsally at a distance equalling its diameter in front of the orbital rim, diameter about twice that of anterior nostril, the margins slightly elevated. Head lateralis system almost similar to that of P. inermis Randall, 1980 (Heemstra 1996: fig. 2), the five mandibular pores prominent, of the Fig. 3. Plectranthias klausewitzi n. sp.; holotype (SMF 29279), 44.9 mm SL. Photography of head in lateral view, showing head squamation and configuration of preopercular edge. Photo by S. Tränkner. aqua vol. 12 no. 1-2006 22

Table I. Proportional measurements of the type specimens of Plectranthias klausewitzi, expressed as percentages of the standard length. Holotype Paratypes Range SMF 29279 SMF 29294 SAIAB 65098 SMF 29294 Standard length (mm) 44.9 54.4 49.5 40.9 39.4 35.5 33.5 Body depth 33.6 36.8 33.0 32.5 34.9 34.2 32.4 36.8-32.4 Body width 16.2 17.7 17.0 17.1 18.3 16.4 16.7 18.3-16.2 Head length 42.3 44.1 46.1 44.4 44.7 42.9 42.8 46.1-42.3 Snout length 10.7 11.1 10.6 8.8 8.3 9.0 7.8 11.1-7.8 Orbital diameter 13.9 13.1 13.5 15.1 15.3 15.5 14.2 15.5-13.1 Interorbital width 4.1 3.8 3.7 4.0 4.3 4.1 4.1 4.3-3.7 Upper jaw length 17.7 18.6 19.0 18.6 19.4 20.8 18.3 20.8-17.7 Caudal peduncle depth 13.6 13.5 13.8 13.8 13.7 13.0 13.5 13.8-13.0 Caudal peduncle length 16.1 15.4 15.7 21.2 21.3 20.0 17.3 21.3-15.4 Predorsal length 41.9 41.3 41.9 43.2 45.9 40.7 41.4 45.9-40.7 Preanal length 67.2 74.1 71.9 69.3 72.5 68.3 68.3 74.1-67.2 Prepelvic length 39.6 46.3 44.0 42.9 38.6 36.7 38.1 46.3-36.7 Dorsal-fin base 46.6 43.8 45.0 45.3 43.9 47.9 43.4 47.9-43.4 First dorsal spine 6.6 5.1 6.2 7.8 * 7.3 7.0 7.8-5.1 Third dorsal spine 22.3 22.4 19.8 21.2 21.4 22.8 20.0 22.8-19.8 Tenth dorsal spine 5.0 5.9 5.2 7.3 5.4 4.4 5.7 7.3-4.4 Fourth dorsal ray 16.3 13.2 16.6 14.9 13.5 20.7 * 20.7-13.2 Anal-fin base 18.0 17.7 16.8 16.1 16.1 16.5 16.9 18.0-16.1 First anal spine 13.1 11.6 9.6 10.2 9.4 8.6 9.9 13.1-8.6 Second anal spine 19.8 20.6 21.2 18.7 18.5 21.2 19.2 21.2-18.5 Third anal spine 13.2 12.8 13.2 11.8 14.0 13.8 13.5 14.0-11.8 Third anal ray 19.7 19.6 15.4 22.8 22.3 23.6 23.6-15.4 Caudal-fin length * * * * * 28.1 * 28.1 Pectoral-fin length 30.1 27.0 33.2 33.8 32.2 34.9 33.0 34.9-27.0 Pelvic-spine length 14.4 14.1 13.9 14.3 15.3 14.8 * 15.3-13.9 Pelvic-fin length 22.2 23.3 23.8 24.6 24.6 23.9 25.2 25.2-22.2 * damaged suborbital series the anterior four large, the orbital channel with a large number of irregularly set small pores, extending around the orbital rim from lower edge of eye to posterior nostril. Scales relatively large, finely ctenoid; preopercle, opercle, subopercle and interopercle scaled, scales on interorbital region reaching almost to posterior nostrils; proximal third to half of soft dorsal and anal fin, as well as of caudal and pectoral fin, scaled, pelvic and spinous portion of dorsal and anal fin scaled at base; snout, suborbital, maxilla, premaxilla, dentary, branchiostegal and gular region and chin without scales. Lateral line complete, arched below dorsal spines 1-6, then aligned approximately in parallel with the dorsal body contour. Dorsal fin originates above the second to third lateral line scale, single and continuous, a distinct notch between spinous and soft rayed portion, the longest spines bearing a cutaneous flap at their tip; dorsal fin base 2.1 (2.1-2.3) in SL; first dorsal spine short, usually about one-third length of third spine 23 and slightly shorter than tenth spine, 6.4 (5.7-8.7) in head; third dorsal spine the longest, 1.9 (1.9-2.3) in head; tenth dorsal spine 8.4 (6.1-9.7) in head; fourth dorsal soft ray longest, 2.6 (2.1-3.4) in head, measurements approximate due the damaged condition of the rays in most of the specimens. Anal fin originates at a vertical line drawn through the base of first or second dorsal soft ray, second anal spine longest, 2.1 (2.0-2.4) in head; second or third anal soft ray longest, several measurements approximate due to the damaged condition of the rays, 2.1 (1.8-2.9) in head. Caudal fin rays broken in most individuals, including the holotype, form and length of the fin and configuration of the rays therefore difficult to determine; the first branched ray especially difficult to identify; the following generalised configuration was found: rays on parhypural segmented, unbranched, occasionally one procurrent ray present, rays on hypurals 1-4 segmented and branched, rays on hypural 5 segmented, unbranched, occasionally one procurrent ray present; parhypural free, hypuaqua vol. 12 no. 1-2006

Plectranthias klausewitzi (Serranidae), a new anthiine fish from the deep Red Sea rals 1-2 not fused, hypural 3-4 weakly ankylosed, hypural 5 free. Live colour not recorded. Preserved specimens pale, nine or ten oblique, narrow dark bars extending from the dorsal midline of body ventrally, occasionally connected mediolaterally with a neighbouring one; roof of occiput and nape very dark, including lateral areas down to upper angle of opercle; a faint stripe extending from origin of lateral line to rear orbital edge; a faint blotch on opercle; a faint spot anteriorly on both the ventral and dorsal half of the caudal fin. The pigment pattern is less discernible in the larger specimens, including the holotype, and therefore not fully represented in Fig. 2. Comparisons: Randall (1980) provided the first taxonomic review and an artificial key to the genus, when he recognised 30 species, including 13 newly described species. Subsequently 14 nominal species were described, until Randall (1996) reviewed the literature again and provided an updated key. He recognised 42 species in total, including two additional new species. Since then, a single species, Plectranthias lamillai from the Juan Fernández Archipelago, Chile, was described by Rojas & Pequeño (1998), which however, has been considered a junior synonym of P. exsul Heemstra & Anderson, 1983 by Anderson & Baldwin (2002). The phylogenetic interrelationships of this speciose genus, however, have not yet been studied. Therefore, no characters are established which could be used to assess the genealogical position of the new species in a cladistic context. Because it could not be positively identified using Randall s keys, it was compared to each congener individually, according to the literature. Only comparisons with species which seem to be morphologically closely related to the new species and/or which occur in deep waters of the Western Indian Ocean are provided herein: Plectranthias helenae Randall, 1980, known from Oahu, Hawaii and probably Taiwan, shares a large number of meristic and morphometric characters with P. klausewitzi and also bears some resemblance in the distribution of pigmented areas in preserved specimens, but is distinct from it in possessing two conspicuous, antrorse preopercular spines versus 0-1, 5 scales between lateral line and origin of dorsal fin vs. 2.5-3, and 13 scales between lateral line and anal-fin base vs. 8-9. Plectranthias lasti Randall & Hose, 1995, known from Western Australia and Queensland, also resembles the new species in a number of morphological characters, but differs in having the fifth dorsal spine longest vs. the third one, a scaled maxilla vs. a scaleless one, and a pale body colour vs. 9-10 oblique bars (preserved specimens) in the new species. Plectranthias nanus, a wide-ranging Indo-Pacific species known from Cocos-Keeling and Christmas Islands to Hawaii, Line and Pitcairn Island, including Micronesia, and the Red Sea, is distinct from P. klausewitzi in possessing unbranched pectoral rays vs. pectoral rays branched except the uppermost, an incomplete lateral line vs. a complete one, two antrorse preopercular spines vs. 0-1, and in a lower maximum standard length (longest SL 39.8 mm [n=62] according to Randall [1980] vs. 54.4 mm); furthermore it is a reef-associated species. Plectranthias rubrifasciatus Fourmanoir & Randall, 1979, known from New Caledonia and Tuamotu Archipelago, appears to bear a resemblance with P. klausewitzi in the pattern of pigmented areas on the body; it differs from the latter in that the uppermost 4-5 pectoral rays are unbranched vs. only the uppermost ray and in having two antrorse preopercular spines vs. 0-1, its fourth dorsal spine is the longest one vs. the third in the new species. Plectranthias megalepis (Günther, 1880) known from Arafura Sea and Ki (Kai) Islands (Indonesia), P. foresti Fourmanoir, 1977, known from the Philippines, and P. maugei, known from Madagascar, share certain morphological characters and similarities in the distribution of pigmented areas in preserved specimens with P. klausewitzi. The species differ altogether from the new species in having only 13 unbranched pectoral rays vs. 14-15, which are branched except the uppermost, and in the fourth or fifth dorsal spine being the longest one vs. the third. Finally the longest spine of these species is lacking a flag-like cutaneous flap while the new species possesses the flap. Specimens of the two deep-dwelling species, which occur in proximity to the type locality of the new species were examined. Plectranthias morgansi can be separated from P. klausewitzi by having all pectoral rays (13-14) unbranched vs. pectoral rays branched (14-15) except the uppermost, a distinctly higher body (body depth 2.5-2.6 in SL vs. 2.67-3.02), and a pigment concentration aligned with lateral line scales 9-16 vs. 9-10 oblique bars. Plectranthias intermedius is distinct from the new species in having 17 soft dorsal fin rays versus 14-15, two antrorse, conspicuous preopercular spines vs. 0-1, and a dark pigmentation along the base of the soft dorsal fin vs. 9-10 oblique, dark bars. aqua vol. 12 no. 1-2006 24

Etymology: The species is named in honour of Prof. Dr. Wolfgang Klausewitz, in recognition of his outstanding contribution to fish taxonomy and of his pioneering concepts of the marine zoogeography of the Indian Ocean. Discussion: Species of Plectranthias are solitary, benthic fishes that usually live on hard, rugged bottoms at depths of 50-400 m in tropical or subtropical areas. Most species are deep dwelling and only attain a small size. While shallow water species generally are more wide-ranging in the Indo- Pacific, the deep water species are usually only known from their type localities and adjacent areas. Hence, museum specimens and data on their distribution ranges and ecology are scarce (Randall 1996, Heemstra 1996). Specimens of P. lasti for example, trawled at depths of about 200 m at the Northwest Shelf of Western Australia, lived at temperatures of 16.0-16.6 C (Randall & Hoese 1995). The collection site of the new species is an extreme deep-water environment, characterised by a rough sea bottom, strong bottom current velocities, elevated temperatures of 21.5-22 C and increased salinities of 38-40, related to the outflow of deep Red Sea water above the seafloor into the Gulf of Aden (Einsele & Werner 1972, Werner & Lange 1975, Beckmann 1984, Bower et al. 2000). The unusually warm and hypersaline nature and the shallow sill at its entrance are the causes for a physical and ecological isolation of the Red Sea past and present, which led to a reduced diversity of deep-sea organisms compared to the Indian Ocean (e.g. Marshall & Bourne 1964, Türkay 1996) and to the evolution of a considerable number of endemic deep-dwelling fishes (Klausewitz 1989, Klausewitz & Zajonz 2000). Most probably the new species represents such a warm-adapted, Red Sea deep-water endemic. Gonad inspection of the holotype revealed that it is a mature female with macroscopically well-developed ovaries. The fact that the oocytes were large and relatively few in number suggests that the spawning mode is benthic rather than pelagic. This would be consistent with the demersal life habit of the genus, and favour genetic isolation under the prevailing oceanographic conditions. Plectranthias klausewitzi is the first deep-dwelling species of the genus recorded from the Red Sea. In spite of a missing concept of the phylogenetic position of the new taxon it is therefore deemed justified to make a name available for it. It is worth noting that of the four species collected at Meteor station 5/230 at least three are new to science (Zajonz & Klausewitz 2002). Comparative material examined: Plectranthias intermedius; ZMH 5132, holotype (78.2 mm SL), IOES 167a, Arabian Sea, 60 nm SW of Socotra, 11 33.9 N 52 54.0 E 11 38.0 N 52 52.0 E, 290-190 m, IIO-Expedition, R.V. Meteor, station 102, Agassiz-trawl, 20 August 1964; ZMH 5133, paratype (91.2 mm SL), IOES 167b, same collection data as holotype. Plectranthias morgansi; ZMH 5131 (46.4 mm SL), IOES 168, 5 nm E of Mombassa, Kenya, 04 05.6 S 39 44.0 E, 208-267 m depth, IIO-Expedition, R.V. Meteor, station 160, Agassiz-trawl, 21 January 1965. ACKNOWLEDGEMENTS Cruise M5 of the R.V. Meteor was funded by the Deutsche Forschungsgemeinschaft (German Research Council; Tu 51/2-1), which also partially supported the present study (grant KR 1758/1-1). The principal cruise scientists H. Thiel (then University of Hamburg) and M. Türkay (SMF) kindly made the fish samples available to us. The author is grateful to F. Krupp who read the manuscript, to G. Eder for preparing the drawing, to S. Tränkner for taking the digital photographs and to H. Zetzsche (all SMF) for preparing X-rays; H. Wilkens and G. Schulze (ZMH) are cordially thanked for providing access to specimens in their care. The valuable comments of two anonymous referees improved the manuscript. REFERENCES AHLSTROM, E. H., BUTLER, J. L., & SUMIDA, B. J. 1976. Pelagic stromateoid fishes (Pisces, Perciformes) of the eastern Pacific: kinds, distributions, and early life histories and observations on five of these from the northwest Atlantic. Bulletin of Marine Science, 26: 285-402. ANDERSON, W. D. & BALDWIN, C. C. 2002. Plectranthias lamillai Rojas and Pequeño, 1998: A Junior Synonym of Plectranthias exsul Heemstra and Anderson, 1983. Copeia, 2002 (1): 233-238. BECKMANN, W. 1984. Mesozooplankton distribution on a transect from the Gulf of Aden to the central Red Sea during the winter monsoon. Oceanologica Acta, 7 (1): 87-102. BOWER, A. S., HEATHER, D. H., & PRICE, J. F. 2000. Character and dynamics of the Red Sea and Persian Gulf outflows. Journal of Geophysical Research, 105: 6387-6414. EINSELE, G. & WERNER, F. 1972. Sedimentary processes at the entrance Gulf of Aden/Red Sea. Meteor Forschungsergebnisse, (C) 10: 39-62. FROESE, R. & PAULY, D. [Eds.] 2006. FishBase. World 25 aqua vol. 12 no. 1-2006

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