Panaqolus claustellifer, Tan & de Souza & Armbruster, 2016

Tan, Milton, de Souza, Lesley S. & Armbruster, Jonathan W., 2016, A new species of Panaqolus (Siluriformes: Loricariidae) from the rio Branco, Neotropical Ichthyology 14 (2), No. e 150033, pp. 1-8 : 2-5

Panaqolus claustellifer , new species

urn:lsid:zoobank.org:act:91C278EC-3C80-4344-8B85-8A433EEB457C

Figs. 1-2

Holotype. CSBD F1702 / AUM 44721 (dual-accessioned), 61.6 mm SL, Guyana, Amazon River - rio Branco drainage, Takutu River near Lethem, 3.47043°, -059.80993°, 27 Nov 2005, L. S. de Souza, N. K. Lujan, D. C. Taphorn, J. A. Hartsell, E. Liverpool, S. Lord.

Paratypes. Guyana, Amazon River - rio Branco drainage: AUM 47717, 1 , 17.6 mm SL, Takutu River rock beach, 3.47058°, -059.80990°, 11 Nov 2007, L. S. de Souza, D. C. Taphorn, J. N. Baskin, T. Geerinckx, J. L. Hwan; AUM 65708, 1 , 16.7 mm SL, same locality data as holotype . Brazil, Amazon River drainage: MZUSP 33704 , 1 , 52.7 mm SL, rio Branco, backwater of Bem Querer rapids (cachoeira do Bem Querer) , Brazil, 1.933°, -061.000°, 1 Aug 1984, M. Goulding .

Diagnosis. Panaqolus claustellifer is diagnosed from most other described species of Panaqolus by its color pattern of darkandlightbarsonthebody,bandsonthefins,andwithdots and vermiculations absent (vs. no bars in P. albomaculatus , P. nix , P. nocturnus , and P. koko , vs. fins unbanded in P. albomaculatus , P. dentex , P. koko , and P. nix , and vs. dots and vermiculations present in P. albivermis and P. maccus ). Additionally, Panaqolus claustellifer is diagnosed from P. albivermis , P. albomaculatus , and P. nix by dentaries forming an acute angle ~70º vs. dentaries forming a very acute angle to dentaries parallel), and from P. koko by spoonshaped teeth with small lateral cusps vs. quadrate teeth with strong lateral cusps. Panaqolus claustellifer is diagnosed from other barred species of Panaqolus by the specific bar number and orientation and color pattern on the head, with bars oriented in a anteroventral-posterodorsal direction (vs. anterodorsal-posteroventral bars in P. gnomus ), having consistently 5 bars (n = 4) on the trunk that do not increase with size (vs. number increasing with size in P. purusiensis and fading at body sizes> 85 mm SL, and vs. 6-12 in P. changae ), and the color pattern on the head of straight lines extending from posterior to the eye to the snout margin, splitting in the middle portion of the line in larger specimens (vs. small, dense reticulate lines in P. changae ).

Description. Morphometrics in Table 1. All counts n = 2 (holotype AUM 44721, paratype MZUSP 33704). Largest observed specimen 61.6 mm SL. Head depth increases at roughly 45º angle between snout tip and anterior margin of the orbit. Horizontal distance from snout tip to anterior margin of orbit greater than horizontal distance from anterior margin of orbit to posterior tip of supraoccipital. Body depth gradually increasing with body profile convex from anterior margin of orbit to greatest body depth at origin of dorsal fin. Body depth decreasing from origin of dorsal fin to posterior margin of adipose fin with a slight increase to the origin of the caudal fin. Ventral surface flat from snout to anus, slightly concave between anus and caudal fin. In dorsal view, head with straight lateral margins forming angle nearly 90º with rounded snout tip.

plates strongly bent forming slight lateral ridge continuous

with exposed cleithrum extending posteriorly to vertical through pelvic-fin origin. Caudal peduncle plate rows five. One preadipose plate, two predorsal plate rows not including nuchal plate.

Supraorbital crest raised slightly. Orbit positioned dorsolaterally on head with orbital opening oriented slightly less than 45º from sagittal plane in anterior view. Interorbital isthmus between supraorbital crests slightly convex. Slight ridge extending from anterolateral corner of nares to dorsal margin of orbit continuous with supraorbital crest. Eye large with iris operculum present. Supraoccipital not raised, profile continuous with dorsal plates. Gill chamber opening ventrally and laterally.

Frontal, infraorbitals, nasal, preopercle, compound pterotic, and suprapreopercle supporting odontodes. Opercle not exposed, not supporting odontodes. Dermal plates on body supporting odontodes, odontodes hypertrophied on holotype. Cheek plates bearing hypertrophied, distally-hooked odontodes (mean 33; holotype 37, MZUSP 33704 paratype 29) evertible to greater than 90º from sagittal plane in dorsal view, longest odontodes reaching to posterior tip of exposed margin of the cleithrum.

Oral disk elliptical, length greater than width. Oral disk width roughly half of head width; posterior margin of lower lip not extending posteriorly past cheek plates. Premaxillae forming roughly 90º angle, dentaries forming roughly 30º angle. Premaxillary teeth 4 on left ramus, dentary teeth 4 on left ramus. All teeth with thick, strong shafts; cusps bifid, medial cusp large and spoon-shaped becoming adze-shaped when worn, lateral cusp small; teeth slightly larger on dentary, medial teeth generally larger than lateral teeth (though medial-most tooth on each ramus is smaller than the second-most medial tooth). Maxillary barbel short, not reaching to posterior margin of lower lip, attached to lower lip for roughly the first half of length. Lips papillose, with papillae decreasing in size toward lip margin.

Fin spines and rays supporting odontodes. Dorsal-fin origin slightly anterior to pelvic-fin origin, with pelvic-fin origin at vertical through origin of first branched dorsalfin ray. Dorsal fin II,7; dorsal-fin spinelet small, V -shaped, Ossified dermal plates with odontodes on head and dorsal-fin spine locking mechanism functional. Posterior lateral surfaces of the body, and ventrally posterior to the dorsal-fin rays free from body, reaching to preadipose anus. Area around dorsal-fin base and snout tip naked. plate. Pectoral-fin origin slightly posterior to orbit. Ventral surface from head to anus largely naked, with small Pectoral fin I,6; adpressed pectoral-fin spine reaching past platelets supporting odontodes distributed ventral to the pelvic-fin spine origin, robust spine having hypertrophied pectoral girdle, extending posteriorly from the pectoral- odontodes increasing in length distally in holotype. Pelvic fin origin almost to the pelvic-fin origin, and forming a fin i,5; pelvic-fin spine reaching past insertion of anal U -shaped pattern posterior to the pelvic-fin insertion fin when adpressed. Anal-fin origin posterior to vertical through origin of posterior-most dorsal-fin ray. Anal fin i,4 (holotype) or i,3 (MZUSP 33704). Adipose-fin spine slightly curved distally, attached to caudal peduncle with membrane with convex posterior margin. Caudal fin i,14,i; caudal fin emarginate with lower lobe longer than upper lobe.

Coloration. Freshly-caught specimens have an orangered base coloration. Live coloration has been described as alternating of dark brown and cream-colored bands ( Miller, 2002). In ethanol, body with light-brown base coloration with dark brown bars. Head with alternating dark lines and light interspaces. Dark lines on head medial to the orbits roughly parallel to sagittal plane, leading from snout margin posterior to the horizontal through posterior margin of orbit. Snout lines connect to each other near the anterior-most and posterior-most ends, leaving a central light-brown, keyhole-shaped opening. Dark line extending from posteroventral margin of eye to anterior of cheek plate. Five oblique dark bars on body oriented in anteroventral-posterodorsal direction, with anterior bars oblique and posterior bars nearly vertical. Dorsal portion of first three bars above horizontal through eye shift to anterodorsal-posteroventral angle; in dorsal view, the first bar roughly forms a W -shape. Dark bars may be bifurcated ventrally with light base color between separate portions of the bars. Extent of split is greatest in secondmost anterior bar, reaching dorsal to horizontal through eye, while vertical extent of splits in second and third bars ventral to lateral line. Posterior bars also expanded dorsally (although not necessarily interspersed by light background color). Posteriormost bar on body extending onto posterior margin of adipose-fin spine and membrane. Fins with an alternating pattern of wide and narrow dark bands on a lighter ran color, bands closest to body wide. Dorsal fin with two wide bands, bands curved in parallel to dorsal-fin margin. Caudal fin with three wide bands, most posterior band only on lower lobe of caudal fin. Three dark wide bands on pectoral fins and pelvic fins, with most proximal dark band starting roughly at fin base.

In small specimens (<20 mm SL), color pattern is slightly different ( Fig. 2 ). More intense reddish coloration present, with dark bars darker brown than in adult specimens. Five oblique dark bars on body oriented in anteroventral-posterodorsal direction; angle of anterior bars does not shift dorsally to anterodorsal-posteroventral direction, and bars not bifurcated. Posteriormost bar on body posterior to adipose fin, thus not extending onto adipose fin as in adult. Dorsal fin with two dark bands, caudal fin with two bands, pectoral fins with two dark bands (with most proximal band starting at base of fin), and pelvic fins with one band (roughly midway on fin length).

Size. Maximum size observed 61.6 mm SL. Known to reach at least 11 cm TL ( Miller, 2002).

Sexual Dimorphism. Male holotype with hypertrophied odontodes well developed posterior to dorsal fin indicating it is in nuptial condition.

Distribution. Panaqolus claustellifer occurs in the Takutu river and the mainstem rio Branco of Brazil and Guyana ( Fig. 3 ).

Ecological notes. Individuals of Panaqolus claustellifer were found in shallow cataracts along the Takutu river, a whitewater system. The substrate was sandy with lateritic rocks interspersed. Surrounding habitat consisted of a narrow strip of gallery forest, but mostly savanna. Small specimens <20 mm SL (AUM 47717, AUM 65708) likely represent young-of-year that have hatched less than a couple weeks prior to collection.

Etymology. From the Latin claustellum, meaning keyhole, and the Latin fero, meaning to bear. Refers to the dark brown lines on the snout surrounding a keyholelike shape of light-brown base coloration. Treated as a masculine adjective.

Remarks. Panaqolus claustellifer is included in Lujan et al. ’s (2015) phylogenetic study. Genetic sequences have been accessioned for the holotype for partial mitochondrial 16S (GenBank number KP959780 ), and Cyt b ( KP960156 ) genes, and nuclear RAG1 ( KP959978 ), RAG2 ( KP960254 ), and Myh6 ( KP960402 ). These are genseq-1 sequences according to the GenSeq Nomenclature ( Chakrabarty et al. 2013).

Panaqolus claustellifer is identified as a Panaqolus , L306, in the aquarium pet trade ( Miller, 2002; Schraml & Schaffer, 2002). Panaqolus claustellifer is listed as Panaque sp. by de Souza et al. (2012) and Panaqolus n. sp. Tacutu L306 by Lujan et al. (2015).

The holotype of the species was dual accessioned at AUM and CSBD because the specimen will be kept at AUM for the near term, but will eventually be repatriated to Guyana. We feel that the specimen will be more readily available to other researchers at AUM, but recognize that the specimen must eventually return to Guyana, and this is the simplest way to ensure that the location of the holotype is known .

Conservation status. Considering that additional samples were carried out in the region without capturing the species, resulting in a reduced known geographic distribution, besides a low number of paratypes, and its potential to the pet trade, Panaqolus claustellifer could be classified as Data Deficient (DD), according to the International Union for Conservation of Nature ( IUCN) categories and criteria ( IUCN Standards and Petitions Subcommittee, 2016). Further studies on biology, ecology and distribution of the species should be strongly encouraged .

Figures

Fig. 1. Panaqolus claustellifer, new species, CSBD F1702/AUM 44721, Takutu River, holotype, adult male, 61.6 mm SL, lateral view is of right side and flipped horizontally. Photo by Milton Tan.

Fig. 2. Panaqolus claustellifer, AUM 65708, Takutu River, paratype, juvenile, 16.7 mm SL. Photo by Milton Tan.

Fig. 3. Map of northern South America showing localities of Panaqolus claustellifer. Holotype and paratype specimens from Takutu river indicated by open circle (CSBD F1702/AUM 44721, AUM 47717, AUM 65708), paratype from mainstem rio Branco indicated by closed circle (MZUSP 33704).