South American electric knifefishes of the genus Archolaemus (Ostariophysi, Gymnotiformes): undetected diversity in a clade of rheophiles Author Vari, Richard P. Author Santana, Carlos David De Author Wosiacki, Wolmar B. text Zoological Journal of the Linnean Society 2012 2012-06-26 165 3 670 699 http://dx.doi.org/10.1111/j.1096-3642.2012.00827.x journal article 10.1111/j.1096-3642.2012.00827.x 0024-4082 5408047 ARCHOLAEMUS LUCIAE SP. NOV. ( FIGS 6 , 7 ; TABLE 2 ) Archolaemus blax , Schwassmann & Carvalho 1985: 233 (in part, specimens from Rio Tapajós and Rio Cupixi; not species redescription or biological information). Ferreira, 1995: 51 ( Brazil , Rio Trombetas basin, Cachoeira Porteira, Cachoeira Vira-Mundo, inhabitant of swift-flowing waters). Diagnosis: Archolaemus luciae is diagnosed from A. blax by the depth of the caudal filament (3.3– 4.8% CL versus 5.0–6.5% CL), the length of the coronomeckelian bone (50% or more the length of Meckel’s cartilage versus less than 20% the length of Meckel’s cartilage), and the length of the posterior ceratohyal (approximately the same length as the ventral hypohyal versus 1.5 times the length of the ventral hypohyal). Archolaemus luciae is diagnosed from A. ferreirai in the length of the gape (the rictus extending posteriorly beyond the vertical through the posterior naris versus falling short of that line) and the distribution of teeth on the internal surface of the endopterygoid (between seven and ten irregularly distributed teeth versus five or six teeth arranged in a single row). Archolaemus luciae is diagnosed from A. janeae in the length of the gape (the rictus extending posteriorly beyond the vertical through the posterior naris versus falling short of that line), the length of the caudal filament (28.6–46.1% LEA versus 16.0–25.7% LEA), the depth of the caudal filament (3.3–4.8% CL versus 5.6–11.2% CL), the form of the premaxilla (the anteroposterior length greater than the transverse width versus the anteroposterior length equal to the transverse width), the distribution of the teeth on the dentary (dentition restricted to the anterior one-half or slightly more of the dorsal margin versus occupying most of the dorsal margin), the length of the coronomeckelian bone (50% or more of the length of Meckel’s cartilage versus less than 20% of the length of Meckel’s cartilage), and the length of the posterior ceratohyal (approximately the same length as the ventral hypohyal versus 1.5 times the length of the ventral hypohyal). Archolaemus luciae is diagnosed from A. orientalis by the pigmentation pattern (the presence of a narrow dark stripe along the lateral line and a broad band of dusky to dark pigmentation overlying the basal pterygiophores of the anal fin, versus the lack of such dark pigmentation), the length of the gape (the rictus extending posteriorly beyond the vertical through the posterior naris versus falling short of that line), the total number of pectoral-fin rays (19–21 versus 16), the total number of anal-fin rays (192–213 versus 164– 186), the form of the premaxilla (the anteroposterior length greater than the transverse width versus the anteroposterior length equal to the transverse width), and the length of the coronomeckelian bone (50% or more the length of Meckel’s cartilage versus less than 20% the length of Meckel’s cartilage). Archolaemus luciae is diagnosed from A. santosi by the pigmentation pattern (the presence of a narrow dark stripe along the lateral line and a broad band of dusky to dark pigmentation overlying the basal pterygiophores of the anal fin versus the lack of such dark pigmentation), the length of the gape (the rictus extending posteriorly beyond the vertical through the posterior naris versus falling short of that line), the length of the caudal filament (28.6–46.1% of LEA versus 14.4– 27.0%), the depth of the caudal filament (3.3–4.8% of CL versus 6.7–9.1%), and the length of the coronomeckelian bone (50% or more of the length of Meckel’s cartilage versus less than 20% the length of Meckel’s cartilage). Figure 7. A, Archolaemus luciae sp. nov. , holotype, female, 267 mm total length, INPA 20960; Brazil, Pará, Rio Trombetas, Cachoeira Porteira, below Furo nas Pedras (approximately 01°05′S, 057°02′W); B, Archolaemus luciae sp. nov. , male, 497 mm total length, INPA 6767; Brazil, Pará, Rio Jamanxim, Rio Tapajós basin, Ilha Terra Preta (05°27′04″S, 055°52′40″W). Description: Morphometric data for the examined specimens of A. luciae are presented in in Table 2 . Body elongate and laterally compressed. Greatest body depth located along abdominal cavity or slightly posterior to that region. Body profile gently convex from rear of head for approximately anterior one-third of body, and then gradually angled posteroventrally along progressively tapering body and caudal filament. Ventral profile of body distinctly convex anteriorly along anterior half of abdominal cavity, and then gradually angled posterodorsally along base of anal fin and caudal filament. Anteriormost perforated lateral line scale located approximately at vertical through origin of pectoral fin. Lateral line continuous, extending from immediately posterior of vertical through origin of pectoral fin to end of caudal filament. Head laterally compressed, widest at opercular region and deepest at nape. Dorsal profile of head varying from nearly straight to slightly concave along antorbital region, and then from straight to slightly convex from that point to rear of head. Ventral profile of head straight and posteroventrally aligned. Snout subconical, anteroventrally directed, and moderately developed to elongate with elongation particularly pronounced in largest examined specimen (INPA 6767; 497 mm TL). Eye small and located laterally on dorsal half of head. Orbital rim covered by membrane and attached to surface tissues of adjoining region of head in six specimens of approximately 97–135 mm TL, partially free on one side in two specimens of approximately 96–97 mm TL, and without membrane and unattached in individuals larger than 135 mm TL. Anterior naris located at end of short tube and positioned short distance posterior of tip of snout, but distant from anterior margin of eye. Posterior naris elliptical, without tube, and located nearer tip of snout than anterior margin of eye. Mouth distinctly inferior, with upper jaw clearly longer than, and overlapping, lower jaw. Gape relatively long and extending posteriorly beyond vertical through posterior margin of posterior nares. Branchial opening moderately elongate, located along posterior margin of opercle and immediately anterior to anterior margin of pectoral-fin origin. Branchial membranes joined at isthmus, and extending posteriorly to under pectoral-fin base. Anus situated proximate to elongate urogenital papilla, and both structures positioned approximately ventral of orbit. Position of anus and urogenital papilla shifting ontogenetically from posterior of vertical through posterior margin of orbit to under or slightly anterior of orbit. Scales small, cycloid, and present from immediately posterior of head to end of caudal filament. Between 127 and 148 (127) scales along lateral line ( N = 15). Between 13 and 16 scales above lateral line at midbody (14) ( N = 29). Scales absent on head. Pectoral fin long, approximately two-thirds of head length, broad and distally pointed, with rounded margin, and lateral rays longer overall. Pectoral-fin rays between ii, 17 and ii, 19 (19) ( N = 29). Anal-fin elongate, extending from vertical through base of pectoral-fin base along most of length of body. Fin margin gently convex anteriorly, and then straight for length of fin, but with rays becoming progressively shorter posteriorly. Anal fin with 22–32 (24) unbranched rays ( N = 29) and 192 to 213 (192) total fin rays ( N = 29). Caudal filament long, with elongation particularly pronounced in largest examined specimen (INPA 6767; 497 mm TL). Coloration in alcohol: Available specimens somewhat faded compared with obvious coloration in live specimens (see Coloration in life). Overall ground head and body coloration tan. Body with obvious but not dark, narrow stripe along lateral line. Extent of stripe variable anteriorly, even in specimens of comparable size, with anterior limit ranging from above centre of pectoral fin to point slightly posterior to vertical through tip of pectoral fin. Body pigmentation darker than overall ground pigmentation along dorsal portion of body. Area overlying basal anal-fin pterygiophores with pterygiophores outlined by very narrow dark surface bars that cumulatively form dusky broad band running along ventral portion of body, with depth of band gradually decreasing posteriorly. Dusky stripe along lateral line and dark ventral band above anal fin separated by more lightly pigmented, broad midlateral stripe. Head lightly coloured ventrally, and somewhat darker on opercle and above horizontal between tip of snout and areas somewhat below orbit. Pectoral and anal fins hyaline. Coloration in life: (Based on recently collected specimens from Rio Teles Pires, Rio Tapajós basin.) Head dark overall, more so dorsal of horizontal between mouth and base of pectoral fin. Body dark from lateral line dorsally, with lateral line more intensely pigmented. Basal portions of anal-fin basal pterygiophores outlined by dark bars on body surface; pigmentation cumulatively forming dark band above base of fin, with height of band gradually decreasing posteriorly. Pigmentation overlying distal portions of basal pterygiophores less intense than that near base of fin, resulting in faint dusky band variably separate, other than anteriorly, from dark band along ventral margin of body. Pectoral fin dusky. Anal fin with rays outlined by dark pigmentation and dusky overall. Distribution: Archolaemus luciae is known within the Amazon basin from the Rio Trombetas basin at Cachoeira Porteira, Cachoeira Vira-Mundo, and the Rio Mapuera, all in the state of Pará , as well as the Rio Tapajós basin, where it has been collected in the Rio Jamanxim and Rio Teles Pires in the state of Mato Grosso . In the state of Amapá , north of the lower Amazon, it has been collected in the Rio Jari that empties into the Amazon and the Rio Araguari that drains independently into the Atlantic Ocean ( Fig. 6 ). Secondary sexual dimorphism: Archolaemus luciae demonstrates pronounced sexual dimorphism in the form of the snout in mature individuals ( Fig. 7 ). Whereas the snout in mature females of the species is overall comparable with that in mature males and females of various congeners, the snout in the large male of A. luciae is distinctly lengthened and more massive anteriorly. Habitat: Ferreira (1995: 51) reported A. luciae (as A. blax ) from swift-flowing water habitats around Cachoeira Porteira and Cachoeira Vira-Mundo in the Rio Trombetas basin. Some of the non-type specimens of the species that originated in the Rio Tapajós were captured in the main stream of shallow rapids and small waterfalls, always over a rocky bottom (J. L. O. Birindelli, pers. comm.). Etymology: The species name, Archolaemus luciae , is in honor of Lucia Py-Daniel of the Instituto Nacional de Pesquisas da Amazônia, in recognition of her many contributions to the knowledge of the fishes of the Amazon and her assistance to the authors over the years. Material examined Holotype : BRAZIL . Pará : Rio Trombetas , Cachoeira Porteira , below Furo nas Pedras (approximately 01°05′S , 057°02′W ), collected by Equipe de Ictiologia do INPA , 19 April 1985 ; INPA 20960 (267). Paratypes : BRAZIL . Collected with holotype : INPA 36381 , 3 (137–276) ; Rio Trombetas , Cachoeira Porteira (approximately 01°05′S , 057°02′W ), collected by Equipe de Ictiologia do INPA , 19 April 1985 ; INPA 20962 , 23 (40–202) ; INPA 20964 , 12 (110–210; 4 CS) ; MPEG 21685 , 1 (138) ; MZUSP 110184 (135) ; USNM 404356 (158) . Rio Mapuera , Cachoeira Porteira (approximately 01°05′S , 057°02′W ); collected by E. Ferreira & M. Jegú ; INPA 20961 , 2 (130–180). Non-type specimens: BRAZIL . Amapá : Rio Cupixi , Rio Araguari basin, bridge on road to Serra do Navio , in channel of river (approximately 00°53′45″N , 052°00′07′W); MZUSP 34920 , 1 (238) . Rio Iratapuru , left bank tributary of Rio Jari , Laranjal do Jari , at Cachoeira de São Raimundo , above Cachoeira de Santo Antonio ( 00°33′59″S , 052°34′40″W ); MZUSP 103446 , 1 (206) . Pará : Rio Trombetas , Oriximiná , above Cachoeira Porteira (approximately 01°03′S , 057°01′W ); INPA 3289 , 1 (210) . Rio Trombetas , Oriximiná , near igarapé Caxipacoré (approximately 01°03′S , 057°01′W ); INPA 3354 , 1 (173) ; INPA 3386 , 1 (160) . Rio Trombetas , Oriximiná , above Cachoeira Vira-Mundo (approximately 01°03′S , 057°01′W ); INPA 3356 , 3 (230–269) ; INPA 3378 , 1 (250) . Rio Mapuera , Cachoeira Porteira (approximately 01°05′S , 057°02′W ); INPA 4371 , 10 (140–235) ; INPA 20957 , 2 (130–141) . Rio Trombetas , Cachoeira Porteira (approximately 01°05′S , 057°02′W ); INPA 4372 , 1 (102) ; INPA 19989 , 1 (275) ; INPA 19990 , 1 (181) ; INPA 20965 , 1 (60) . Trombetas , Oriximiná , Cachoeira Vira-Mundo (approximately 01°05′S , 057°02′W ); INPA 5081 , 1 (220) ; INPA 5082 , 1 (180) . Rio Jamanxim , Rio Tapajós basin, Ilha Terra Preta ( 05°27′04″S , 055°52′40″W ); INPA 6767 , 1 (497) ; INPA 6812 , 6 (92–130) . Rio Tapajós , São Luis do Tapajós (approximately 04°25′S , 056°13′W ); MZUSP 24268 , 1 (400) . Rio Tapajós basin, Jacareacanga , rapids along Rio Teles Pires , below Sete Quedas (approximately 06°13′20′S, 057°45′10″W ); MZUSP 96130 , 1 (229) . Mato Grosso : Rio Tapajós , Paranaíta, Rio Teles Pires , near ferry crossing of rodovia MT-416; MZUSP 95630 , 4 (148–186) . Rio Peixoto de Azevedo , Município do Peixoto de Azevedo , tributary of Rio Teles Pires near Peixoto de Azevedo (approximately 10°10′S , 054°50′W ); MZUSP 96618 , 1 (203) . Rio Teles Pires , Itaúba , below mouth of Rio Renato (approximately 11°03′43″S , 055°16′33″W ); MZUSP 99362 , 2 (363–445) . Rio Tapajós , Itaúba , Rio Teles Pires (approximately 11°39′11″S , 055°42′14″W ); MZUSP 95909 , 1 (409) . Rio Braço Norte , Novo Mundo , above Pequena Centrais Hidreléctica Braço Norte IV (approximately 09°47′S , 054°54′W ); MZUSP 106461 , 1 (292) . Rio Teles Pires , Município da Paranatinga , Fazenda do Antônio Bezerra (approximately 10°20′S , 054°45′W ); MZUSP 107923 , 1 (447). ARCHOLAEMUS ORIENTALIS SP. NOV. STEWART,