Ancistrus luzia, Neuhaus & Britto & Birindelli & Sousa, 2022

Neuhaus, Emanuel B., Britto, Marcelo R., Birindelli, José Luís O. & Sousa, Leandro M., 2022, A new species of Ancistrus (Siluriformes: Loricariidae) from Tapajós and Xingu basins, Brazil, Neotropical Ichthyology (e 210129) 20 (1), pp. 1-21 : 3-13

Ancistrus luzia , new species urn:lsid:zoobank.org:act:31D5520F-B248-4226-8413-896A0535A341

( Figs. 1–3 ; Tab. 1)

Ancistrus L 159. ―Stawikowski, 1994:145 [DATZ magazine, new imports from Brazil, figs. 6 and 7].

Ancistrus sp. “ lineolatus ”. ― Ohara et al., 2017:259 [identification guidebook from Teles Pires].

Holotype. MNRJ 51458 , male, 75.9 mm SL, Brazil, Mato Grosso, Guarantã do Norte, rio Teles Pires basin, unknown stream next to bridge on road about 8 km from the road BR-163, 09°47’15”S 54°57’33”W, 1 Oct 2008, M. R. Britto, J. Gomes, F. R. Carvalho & L. Fries.

Paratypes. Brazil, Mato Grosso, rio Tapajós basin: MNRJ 35484 , 11 , 26.1–74.7 mm SL (10, 33.4–74.7 mm SL), collected with the holotype. MNRJ 24622 , 9 , 1 cs, 33.2–62.9 mm SL, Terra Nova do Norte, riacho Doce, tributary of rio Bastião , rio Teles Pires basin, 10°33’00”S 55°4’25”W, 23 Jan 2002, P. Buckup, A. Aranda, F. Silva & C. Figueiredo. MNRJ 24641 , 3 , 47.8–52.2 mm SL, Peixoto de Azevedo , tributary of rio Peixoto de Azevedo at road BR-080, rio Teles Pires basin, 10°25’57”S 54°10’59”W, 24 Jan 2002, P. Buckup, A. Aranda, F. Silva & C. Figueiredo. MNRJ 24692 , 2 , 58.6–71.2 mm SL, Carlinda, tributary of rio Teles Pires , left margin, at road MT-208, 09°59’04”S 55°46’03”W, 23 Jan 2002, P. Buckup, A. Aranda, F. Silva & C. Figueiredo. MNRJ 35486 , 3 , 1 cs, 56.2–60.9 mm SL, Guarantã do Norte , tributary of rio Braço do Norte , Teles Pires basin, 09°56’55”S 55°01’51”W, 2 Oct 2008, P. Buckup, J. Maldonado, J. Birindelli, C. Chamon & W. Felzmann. MNRJ 35487 , 11 , 25.6–34.9 mm SL (1, 34.9 mm SL), Novo Mundo , stream and wetland at the road between Novo Mundo and Alta Floresta, 10°03’37”S 55°26’54”W, 2 Oct 2008, M. Britto, J. Gomes, F. Carvalho, L. Fries, F. Jerep & C. Zawadzki. MNRJ 35489 , 2 , 52.0– 77.1 mm SL, Alta Floresta , corredeira Boca Quente, rio Teles Pires , 09°38’42”S 55°59’23”W, 3 Oct 2008, M. Britto, J. Gomes, C. Chamon, L. Fries, F. Jerep & C. Zawadzki. MZUEL 20724 , 2 , 40.2–54.6 mm SL, collected with the holotype. MZUEL 20725 , 1 , 69.0 mm SL, Alta Floresta , corredeira Boca Quente, rio Teles Pires , 09°38’42”S 55°59’23”W, 3 Oct 2008, M. Britto, J. Gomes, C. Chamon, L. Fries, F. Jerep & C. Zawadzki. MZUEL 20726 , 1 , 64.3 mm SL, Carlinda, tributary of rio Teles Pires , left margin, at road MT-208, 09°59’04”S 55°46’03”W, 23 Jan 2002, P. Buckup, A. Aranda, F. Silva & C. Figueiredo. MZUSP 62659 , 8 (4, 42.6–54.8 mm SL), Claudia, córrego Loanda, at road BR-163, rio Teles Pires , 11°25’00”S 55°21’00”W, 21 Feb 1998, M. I. Landim & C. Moreira. MZUSP 95904 , 6 (3, 61.0– 82.9 mm SL), Itauba, rio Teles Pires , 11°03’44”S 55°19’08”W, 26 Sep 2007, J. Birindelli & P. H. Carvalho. MZUSP 96150 , 4 (2, 54.9–55.1 mm SL), Paranaíta, rio Teles Pires , 09°26’58”S 56°29’19”W, 28 Sep 2007, L. Sousa & A. Netto-Ferreira. MZUSP 96820 , 46 , 1 cs (5, 45.7–79.5 mm SL), Peixoto de Azevedo , Cachoeira da Neblina , in a tributary of rio Peixoto de Azevedo , rio Teles Pires , 18 Oct 2007, J. Birindelli, L. Sousa, A. Netto-Ferreira, M. Sabaj-Perez & N. Lujan . Pará, rio Tapajós basin: MZUSP 96834 , 4 (2, 22.1–29.1 mm SL), Novo Progresso, tributary of rio Braço do Norte, rio Peixoto de Azevedo , rio Teles Pires , at bridge of the road BR-163, 09°25’55”S 54°52’11”W, 19 Oct 2007, J. Birindelli, L. Sousa, A. Netto-Ferreira, M. Sabaj-Perez & N. Lujan. MZUSP 99877 , 28 (18, 29.6–59.8 mm SL), Jacareacanga, rio Teles Pires , downstream Sete Quedas, 09°18’42”S 56°46’47”W, 9 Jun 2008, L. Sousa & A. Netto-Ferreira. MZUSP 99931 , 4 (2, 58.7–61.1 mm SL), Jacareacanga, tributary of the left margin of rio Teles Pires , downstream of Sete Quedas, 09°18’27”S 56°47’38”W, 9 Jun 2008, L. Sousa & A. Netto-Ferreira .

Non-types. Brazil, Mato Grosso, rio Tapajós basin: MNRJ 35490 , 1 , 40.4 mm SL, Alta Floresta, cachoeira do Limão, at rio Cristalino , tributary right margin of rio Teles Pires , 09°32’17”S 55°54’14”W, 4 Oct 2008, P. Buckup, F. Carvalho, J. Birindelli, J. Gomes, F. Becker, R. Silvano & W. Felzmann. MNRJ 35491 , 3 , 53.6–61.8 mm SL, Alta Floresta , igarapé Corgão, and adjacent margin of rio Peixoto de Azevedo , Teles Pires basin, 09°43’37”S 55°50’06”W, 4 Oct 2008, P. Buckup, F. Carvalho, J. Birindelli, J. Gomes, F. Becker, R. Silvano & W. Felzmann. MNRJ 35492 , 1 , 32.2 mm SL, Alta Floresta , stream in front of Ilha do Refúgio , rio Teles Pires , 09°38’40”S 56°01’58”W, 4 Oct 2008, M. Britto, J. Gomes, C. Chamon, J. Maldonado, F. Jerep & C. Zawadzki. MNRJ 35493 , 1 , 32.7 mm SL, Alta Floresta , Ilha do Domingão , rio Teles Pires , 09°38’13”S 55°58’55”W, 4 Oct 2008, M. Britto, J. Gomes, C. Chamon, J. Maldonado, F. Jerep & C. Zawadzki. MZUSP 95639 , 1 , 36.7 mm SL, Paranaíta, rio Teles Pires , near the ferry of the road MT-426, 09°27’07”S 56°30’46”W, 27 Sep 2007, L. Sousa & A. Netto-Ferreira. MZUSP 96564 , 1 , Itaúba, stream at road BR-163, tributary of rio Teles Pires , 11°06’51”S 55°18’25”W, J. Birindelli & P. H. Carvalho . Pará, rio Xingu basin: LIA 3996 , 2 , 39.0–42.0 mm SL, igarapé at Morro do Félix, RESEX do Rio Xingu, Altamira , 05°22’18”S 52°55’37”W, 17 Set 2016, A. Gonçalves & M. D. Silva. LIA 7657 , 4 , 25.1–66.1 mm SL, igarapé without name, 03°28’39”S 52°32’36”W, 15 Set 2012, D. Bastos. MNRJ 35483 , 1 , 34.1 mm SL, stream at road BR-163, about 14 km north of Castelo dos Sonhos, 30 Sep 2008, M. Britto, J. Gomes, F. Carvalho & L. Fries. MNRJ 35503 , 2 , 36.1–42.9 mm SL, Altamira, rio Curuá , rio Iriri basin, 08°06’35”S 55°00’58”W, 30 Set 2008, P. Buckup, J. Maldonado, C. Zawadski, C. Chamon & F. Jerep. MNRJ 35504 , 6 , 22.5–48.5 mm SL (4, 37.5–48.5 mm SL), Altamira, rio Curuá , rio Iriri basin, small stream upstream the first waterfall, 08°44’02”S 54°57’45”W, 1 Oct 2008, M. Britto, J. Gomes, F. Carvalho & L. Fries. MNRJ 35505 , 8 , 23.4–71.6 mm SL (5, 36.9–71.6 mm SL), Altamira, rio Curuá , rio Iriri basin, waterfall of rio Curuá , 54 km from Castelo dos Sonhos, 08°44’06”S 54°57’43”W, 1 Oct 2008, M. Britto, J. Gomes, F. Carvalho & L. Fries. MNRJ 35506 , 2 , 61.3–80.7 mm SL, rio Curuá , rio Iriri basin, waterfall of rio Curuá , upstream the first waterfall, 08°44’10”S 54°57’47”W, 1 Oct 2008, M. Britto, J. Gomes, F. Carvalho & L. Fries. MZUEL 20727 , 1 , 62.5 mm SL, rio Curuá , rio Iriri basin, waterfall of rio Curua , upstream the first waterfall, 08°44’10”S 54°57’47”W, 1 Oct 2008, M. Britto, J. Gomes, F. Carvalho & L. Fries .

Diagnosis. Ancistrus luzia is distinguished from its congeners, except A. claro Knaack, 1999 and A. centrolepis Regan, 1913 , by the singular body color pattern, consisted of dark-vermiculated stripes on head, dorsal and lateral plates of trunk (vs. body uniformly colored or with light or dark spots or blotches over head or dorsal and lateral plates of trunk). Ancistrus luzia is distinguished from A. claro by its narrower head (head width 30.8–35.1% vs. 35.2–38.2% HL) and greater internostril distance (18.7–23.7% vs. 14.9– 17.0% HL), and from A. centrolepis by the absence of rows of greatly enlarged odontodes on the lateral plates (vs. presence of one to three rows of enlarged odontodes on the lateral plates). Juveniles of A. leucostictus (Günther, 1864) might show lines similar to A. luzia , but color changes to light, large spots as specimens grow. In addition, the new species is distinguished from its congeners that inhabit the Tapajós basin by the presence of adipose fin fully developed (vs. adipose fin absent in A. parecis Fisch-Muller, Cardoso, da Silva & Bertaco, 2005 , A. tombador Fisch-Muller, Cardoso, da Silva & Bertaco, 2005 , and vestigial adipose fin or absent in A. krenakarore de Oliveira, Rapp Py-Daniel & Zuanon, 2016 ). Ancistrus luzia differs from A. ranunculus Muller, Rapp Py-Daniel & Zuanon, 1994 , the only described species from the rio Xingu, by the smaller body size in adults, smaller gill opening (HL/interbranchial distance equals to 1.7 to 2.0 vs. 2.3 to 3.9) and narrower cleithral width (SL/cleithral width equals to 2.8–3.2 vs. 2.1–2.9).

Description. Morphometrics data in Tab. 1. Dorsal profile convex, ascending from the tip of snout until posterior limit of supraoccipital; almost straight to slightly convex between supraoccipital and dorsal-fin origin, descending from this point until posterior margin of adipose-fin base; slightly concave between end of adipose and first procurrent caudal-fin ray. Body width greatest at opercular region, progressively narrowing until end of caudal peduncle. Greatest body height at dorsal-fin origin and lowest at the caudal peduncle, near adipose-fin terminus. Body in cross section horizontally elliptical at abdominal region and vertically oval at caudal peduncle. Ventral profile gently convex between tip of snout and pelvic-fin origin, and then straight between pelvic fin and first procurrent caudal-fin ray.

Body covered with bony plates, except along dorsal-fin base, and ventral region between tip of snout and anal-fin origin. Plates arranged in four series from head to pelvic-fin base, with ventral series absent. Plates arranged in five series in trunk from pelvic-fin base to vertical through adipose-fin base with mid-dorsal and mid-ventral series ending at the latter point. Plates arranged in three series at the narrowest part of the caudal peduncle. Small sets of odontodes eventually occurring over the ventral skin close to pectoral-fin insertion. Lateral line visible from posterior margin of compound pterotic to posterior end of caudal peduncle, always following median plate series.

Body plates and fin rays covered with odontodes. Odontodes in regular rows on the plates, larger on posterior margin. Some individuals have odontodes just before insertion of unbranched anal-fin ray, arising from expanded transverse process of first pterygiophore of anal fin. Odontodes larger on distal half of pectoral-fin spine and partially covered with dermic membrane. Odontodes on pelvic-fin unbranched rays larger at ventral portion. Median plates 23(9), 24*(53), 25(2), 26(1); mid-dorsal plates 10(2), 12(1), 13(4), 14(6), 15(16), 16*(19), 17(15), 18(1), 19(1); mid-ventral plates 18(3), 19(38), 20*(17), 21(6), 22(1); plates along dorsal-fin base 5(3), 6*(61), 7(1); plates between end of dorsal and adipose fins 6(1), 7*(46), 8(17), 9(1); plates between adipose and caudal fins, 2(41), 3*(24); preanal plates 2(1), 3(3), 4*(59), 5(2); ventral plates between anal-fin base and caudal fin 12(4), 13*(54), 14(5), 15(1). Urogenital pore covered with tubularshape urogenital papilla.

Rounded snout, in dorsal view, with naked margin. See description on Sexual Dimorphism for details on snout and tentacles. Presence of subdermal platelets bordering the naked margin and/or in the base of tentacles ( Fig. 2 ). Oral disc rounded, with small papillae on its inner surface decreasing in size toward external margin. Lower lip larger than upper, not reaching pectoral girdle. Barbel short, length nearly half of orbit diameter and free from lower lip in most specimens. Bicuspid teeth with elongate mesial cusp and short lateral cusp, cusps separated from each other by V-shaped notch; 49–76 (mean 62) teeth in premaxilla, 48–75 (mean 62) dentary. Post-opercular region naked, with zero to eight dermal platelets normally grouped near anterior margin of compound pterotic; 6–14 (mean 11) evertible cheek odontodes distally hooked, hyaline at base and yellowish amber at tip.

Dorsal-fin origin slightly anterior to pelvic-fin origin; dorsal fin II,6(1), II,7*(63) or II,8(1). First unbranched ray (spinelet) short and V-shaped (one specimen with spinelet atrophied), second unbranched ray (dorsal spine) well developed. Last branched-rays reaching or almost reaching pre-adipose plate, when adpressed. Pectoral fin I,6*(65), when adpressed reaching pelvic-fin insertion in small individual (30 mm) or reaching half-length of pelvic unbranched rays in larger specimens. Pelvic fin i,5*(65), with posterior margin reaching approximately half of anal-fin rays. Anal fin i,3(1) or i,4*(63). Caudal-fin truncate; i,14,i*(65); with upper lobe shorter than lower; dorsal and ventral procurrent caudal-fin rays 5*(28) or 6(16) and 3(8), 4*(31), or 5(1), respectively.

Eyes rounded, located dorsolaterally on head. Orbit delimited dorsally by prefrontal plate, frontal and sphenotic, and ventrally by infraorbitals four to six. Anterior and posterior nares located dorsally on head, separated from each other by a flap of skin. Anterior naris with tubular expansion of skin. Posterior naris separated from orbit by prefrontal plate and frontal. Six infraorbitals in total.

Palatine splint present in one specimen and absent the other two cleared and stained. When present thin, elongate and ossified, located near palatine cartilage and lateral to palatine. Four branchiostegal rays, only first one associated with posterohyal; remaining three supported by branchiostegal membrane. Three basibranchial elements, only first one ossified. Five pairs of hypobranchial elements, only first ossified. Five pairs of ossified ceratobranchials; first with large accessory flange supporting first row of modified gill rakers; fifth expanded, with numerous small teeth on dorsomesial edge, and supporting row of modified gill rakers on dorsal surface. Four ossified epibranchials. Two infrapharyngobranchials: one associated with third epibranchial and the other with fourth. Upper pharyngeal tooth plates with teeth along entire ventral portion.

Vertebrae 27, with sixth vertebra and eighth to 14 th (2) or 15 th (1) vertebrae bearing ribs. First rib (associated with sixth centrum) conspicuously larger. Neural spine absent in vertebral centrum eight. Centra with bifid neural spines: 10–15(3). Bifid neural arches reaching dorsal dermal plates, except for ninth centrum, reduced. Hemal spines present on vertebrae 9–27(1) or 10–27(2) and reaching ventral dermic plates from 18 th or 19 th. Dorsal fin with eight pterygiophores, first two sutured to each other and to neural spine of seventh centrum, and in some specimens also to anterior portion of eighth centrum; transverse process present on first five proximal radials; last one with pair of elongate posterior processes. Branched rays of pectoral fin supported by three radials. Lateral and internal pairs of anterior processes of basipterygia reaching each other at central portion of pelvic girdle. First pterygiophore of anal fin contacting hemal spine of centrum 14.

Color in alcohol. Ground color of head, dorsum and lateral portions of trunk brown,

with striated dark lines. In snout, dark lines somewhat parallel to each other, straight or curved, eventually branched, and longitudinal to axis of body. Dark lines outline bones of neurocranium and predorsal plates posterior to orbit. Lips yellowish brown. Ventral region of abdomen brown, without lines or blotches (with exception of two specimens of MNRJ 24622 that showed rounded dark brown blotches). All fins with brown interradial membranes. Dorsal fin sometimes with a dark blotch at base of membrane,

between dorsal-fin spine and first branched ray. Dorsal-fin rays with two to five blotches over rays usually expanded over membranes. Caudal fin with dark spots over rays and interradial membranes, forming vertical, straight to sinuous and discontinuous stripes.

Vertical dark band close to caudal-fin base, posterior to platelets. Tips of caudal fin and adjacent branched rays yellowish white or hyaline, some individuals with tip of dorsal fin and adjacent branched rays hyaline. Color of pectoral and pelvic fins similar to dorsal fin. Juveniles have caudal fin with wide, vertical dark band; some specimens with tip of dorsal spine and adjacent branched rays, as well as tip of caudal-fin lobes red-brown colored (MZUSP 99877; Figs. 3A, B ). In populations from rio Curuá, the juveniles have a similar color pattern described above ( Figs. 3C, D ). Nevertheless, in adults lateral and dorsal plates do not have vermiculation but an inconspicuous dark longitudinal band passing through median plates instead. Paired and dorsal fins without spots. Caudal fin brown with base and distal portions dark brown. All membrane fins are brown ( Fig. 4A ).

Color in life. Live specimens show similar color pattern observed in specimens preserved in alcohol, except for ground coloration more greenish, and dark lines more conspicuous ( Figs. 4B , 5 , 6 ).

Sexual dimorphism. Naked margin of snout narrower in females and juveniles (width smaller than distance between nares) and wide in adult males (width equal or greater than distance between nares). Naked margin in nuptial males reaching the anterior margin of nasal openings. Fleshy tentacles on naked region visible in individuals larger than 30 mm, well developed in nuptial males. Males with numerous and larger tentacles than females but number and size vary among specimens of same sex and similar standard length. Some adult females without tentacles (observed in MZUSP 96820). Tentacles along the snout margin smaller and, with a few exceptions, unbranched. Most tentacles branched in the medial row. Some mature females with yellowish-white dots around urogenital papilla ( Fig. 7 ).

Etymology. Named after “Luzia” (Lapa Vermelha IV Hominid 1), a female Homo sapiens skeleton and one of the oldest human remains found in the Americas (11,000 – 11,500 years before present), in 1974 and 1975 during excavations coordinated by the French archaeologist Annette Lamin-Emperaire (1917–1977) from the site of Lapa Vermelha IV, Lagoa Santa region, municipality of Pedro Leopoldo, state of Minas Gerais, Brazil (Neves et al., 1999). The skeleton is deposited at Museu Nacional Biological Anthropology collection (catalogue number 01959), Universidade Federal do Rio de Janeiro, and was recovered again after the fire that hit the institution on September 2, 2018 by Museu Nacional Rescue team, becoming a symbol of institutional hope and resilience. A noun in apposition.

Geographical distribution. Ancistrus luzia is known from rio Teles Pires and its tributaries (rio Tapajós basin) and small to medium tributaries of middle and upper rio Xingu basin ( Fig. 8 ) always associated with moderate water flow and rocky substrates ( Fig. 9 ).

Conservation status. Ancistrus luzia is widely distributed across the Teles Pires basin and in different tributaries of the rio Xingu. A substantial number of cataloged specimens from distinct localities and distinct field expeditions over the past two decades suggest that the species is not threatened. In the rio Xingu, part of its tributaries at Volta Grande region were flooded by the Belo Monte Hydropower dam, but specimens were recently collected (non-cataloged material) in small streams not affected by the dam. Thus, A. luzia may be categorized as Least Concern (LC) according to the categories and criteria of the International Union for Conservation Nature (IUCN Standards and Petitions Subcommittee, 2019).

Figures

FIGURE 1 | Ancistrus luzia, holotype, MNRJ 51458, male, 75.9 mm SL, Brazil, Mato Grosso, Guarantã do Norte, a tributary of rio Teles Pires, Tapajós basin. Black spots in the ventral view are parasites.

FIGURE 2 | Ancistrus luzia, paratype, MNRJ 24622, cs, female, 48.9 mm SL, showing the subdermal platelets bordering the naked margin of snout. Arrows indicate platelets.

FIGURE 3 | Color pattern of juvenile specimens of Ancistrus luzia. A, B. MZUSP 99877, 33.2 mm SL, from rio Teles Pires basin. C, D. MNRJ 35504, 37.5 mm SL, from the rio Curuá, rio Xingu basin.

FIGURE 4 | Lateral view of Ancistrus luzia, MNRJ 35505, 71.6 mm SL, rio Curuá, Xingu basin. A. Preserved specimen. B. Specimen in life.

FIGURE 5 | Ancistrus luzia in life, MZUSP 96564, rio Teles Pires, rio Tapajós basin.

FIGURE 6 | Ancistrus luzia in life, specimen not preserved, 80.6 mm SL, rio Bacajaí, 03°35’13”S 51°46’00”W, tributary to middle rio Xingu.

FIGURE 7 | Ventral view of pelvic girdle of Ancistrus luzia showing differences in urogenital papillae of female (63.2 mm SL) and male (80.6 mm SL).

FIGURE 8 | Geographic distribution of Ancistrus luzia. Star represents its type locality.

FIGURE 9 | Habitats of Ancistrus luzia: (above) rio Teles Pires, Itauba, Mato Grosso (MZUSP 95904), photo by José L. O. Birindelli; (middle) rio Bacajaí (03°35’13”S 51°46’00”W), tributary to middle rio Xingu, photo by Leandro Sousa; and (below) igarapé without name, Middle Xingu, Altamira, Pará (LIA 7657), photo by Douglas Bastos.