Hypancistrus seideli, Sousa & Sousa & Ribeiro & Sabaj & Zuanon & Py-Daniel, 2025

Hypancistrus seideli , new species

urn:lsid:zoobank.org:act:

( Figs. 5–6 View FIGURE 5 View FIGURE 6 ; Tab. 2 View TABLE 2 )

Hypancistrus L66. — Stawikowski, 1990:520 (aquarium fish atlas; citation and brief description). — Seidel, Evers, 2005:588–90 (book; citation and brief description). — Seidel, Evers, 2005:576–79 (Book; citation and brief description). — Seidel, 2008:111 (book, citation and brief description). — Cardoso et al., 2016:209 (article on cytogenetics). — Araújo et al., 2017:300 (article on Xingu ornamental fishery).

Hypancistrus L236. — Glaser, Glaser, 1995:94 (aquarium fish catalog, citation and brief description). — Schraml, Schäfer, 2004:172 (aquarium fish magazine report). — Seidel, Evers, 2005:592–94 (book; citation and brief description). — Seidel, 2008:113 (book, citation and pictured). — Evers, 2021:06 (book about the history of this morphotype on the trade).

Hypancistrus L287. — Seidel, 2000:14 (aquarium fish catalog, citation and brief description). — Schraml, Schäfer, 2004:200 (atlas of aquarium fish). — Seidel, Evers, 2005:602 (Book). — Seidel, 2008:114 (book, citation and pictured).

Hypancistrus View in CoL L333. — Werner, 2003:35 (aquarium fish magazine, citation and brief description). — Schraml, Schäfer, 2004:215 (aquarium fish catalog). — Seidel, 2008:115 (book, citation and brief description). — Cardoso et al., 2016:209 (article on cytogenetics). — Reis et al., 2021 (article on feed management). — Borges et al., 2021:5 (citation). — Reis et al., 2022:3718 (article on sexual dimorphism). — Krings et al., 2023:3 (figure of mouth structures).

Hypancistrus View in CoL L399. — Werner, 2005:56–57 (aquarium fish magazine, citation and brief description). — Seidel, 2008:115 (book, citation and pictured).

Hypancistrus L400. — Werner, 2005:56–57 (aquarium fish magazine, citation and brief description). — Seidel, 2008:115 (book, citation and pictured).

Hypancistrus sp.1 . — Camargo et al., 2013:173–81 (book, ornamental fish). — Ramos et al., 2015:97 (citation).

Hypancistrus View in CoL “complexo pão”. — Ramos et al., 2015:97 (citation).

Hypancistrus sp. — Araújo et al., 2017:300 (citation). — Fitzgerald et al., 2018:105, fig. 1 (list of species). — Reis et al., 2021:2 (article on feed management). — Reis et al., 2022:3718 (article on sexual dimorphism). — Almeida et al., 2023 (article on cytogenetics). — Reis et al., 2023:02 (biotechnology and nutrition).

Hypancistrus sp. “pão”. — Santos et al., 2023:29 (article on cytogenetics).

Holotype. INPA-ICT 61050 , 98.1 mm SL, Vitória do Xingu, Itaubinha, pedral, Pará State, Brazil, 02°53’21”S 51°56’26”W, 4 Nov 2008, L. Rapp Py-Daniel, H. Anatole & J. Bessa. GoogleMaps

Paratypes. All from Brazil, Pará State: ANSP 185238 , 9, 72.2–95.3 mm SL, rio Acarai , upstream from confluence with rio Xingu at Porto de Moz, 02°04’34”S 52°20’42”W, 10 Nov 1994, A. M. Zanata, J. G. Lundberg & L. Rapp Py-Daniel. GoogleMaps ANSP 194643 , 13, 46.3–103.4 mm SL, rio Xingu , deep channel along right bank of river ca. 38 km southeast of Vitória do Xingu, 03°05’32.39”S 51°44’14.1”W, 21 Sep 2013, M. H. Sabaj, L. M. Sousa, A. Gonçalves, N. K. Lujan, D. B. Fitzgerald, P. Madoka Ito, A. Oliveira, R. Robles & ornamental fishermen. GoogleMaps ANSP 194954 , 15, 33.4–83.1 mm SL, rio Xingu (lower Volta Grande ), rocky outcrop in main channel, 03°7’45”S 51°39’55.1”W, 20 Sep 2013, M. H. Sabaj, L. M. Sousa, A. Gonçalves, N. K. Lujan, D. B. Fitzgerald, P. Madoka Ito, A. Oliveira, R. Robles & fishermen. GoogleMaps ANSP 194988 , 18, 41.1–102.8 mm SL, rio Xingu , ca. 50 m off right bank of main channel ca. 1 km downstream of Porto de Moz, 01°44’42.4”S 52°14’53.9”W, 24 Sep 2013, M. H. Sabaj, A. Gonçalves, N. K. Lujan, D. B. Fitzgerald, P. Madoka Ito, A. Oliveira, R. Robles & fishermen. GoogleMaps ANSP 195292 , 2, 94.0–116.0 mm SL, rio Xingu , along left bank, ca. 10.4 km southwest of Senador José Porfírio, 02°38’54.3”S 52°01’41.9”W, 7 Mar 2014, M. Arce, A. P. Gonçalves, J. A. S. Zuanon, D. B. Fitzgerald, R. Robles, D. R. G. Ribeiro, L. M. Sousa & fishermen D. R. Costa (Dani), D. R. Costa (Ronca), N. S. Balão (Nelson) & A. S. Oliveira (Tonho). GoogleMaps ANSP 195384 , 9, 44.6–116.0 mm SL, rio Xingu , along right bank of major right braid, directly in front of Tapará village, ca. 14.5 km northeast (downstream) of Porto de Moz, 01°38’36.6”S 52°10’13.0”W, 5 Mar 2014, M. Arce, A. P. Gonçalves, J. A. S. Zuanon, D. B. Fitzgerald, R. Robles, D. R. G. Ribeiro, L. M. Sousa & fishermen D. R. Costa (Dani), D. R. Costa (Ronca), N. S. Balão (Nelson) & A. S. Oliveira (Tonho). GoogleMaps AUM 74486 , 4, 51.6–83.5 mm SL, same data as ANSP 194643. GoogleMaps INPA-ICT 31472 , 63, 38.26–107.33 mm SL, collected with holotype. GoogleMaps INPA-ICT 40457 , 16, 38.8-80.6 mm SL, Anapu, 03°28’20”S 51°11’52”W, 20 Sep 2013, M. Hardman, A. S. Oliveira, P. M. Ito, V. Machado, D. B. Fitzgerald, A. P. Gonçalves, L. M. Sousa & M. Sabaj-Péres. GoogleMaps INPA-ICT 40502 , 17, 42.6-85.3 mm SL, Senador José Porfírio, 02°35’27”S 51°57’15”W, 21 Sep 2013, D. R. G. Ribeiro, D. B. Fitzgerald, A. P. Gonçalves, M. Arce, D. Bastos, L. Rapp Py-Daniel, Dani & M. Sabaj-Péres. GoogleMaps INPA-ICT 40494 , 8, 34.3–54.8 mm SL, Anapu, 03°28’20”S 51°11’52”W, 21 Sep 2013, R. R. Reyes, D. B. Fitzgerald, A. P. Gonçalves, M. Arce, D. Bastos, L. Rapp Py-Daniel, L. M. Sousa, Dani & M. Sabaj-Péres. GoogleMaps INPA-ICT 40520 , 10, 35.8–101.0 mm SL, Vitória do Xingu, 02°52’48”S 52°00’36”W, 22 Sep 2013, A. R. Martins, D. R. G. Ribeiro, R. R. Reyes, D. B. Fitzgerald, J. Zuanon, M. Arce, A. P. Gonçalves, M. Sabaj-Péres. GoogleMaps INPA-ICT 40533 , 6, 31.6–55.4 mm SL, Vitória do Xingu, 02°52’48”S 52°00’36”W, 22 Sep 2013, A. R. Martins, D. R. G. Ribeiro, R. R. Reyes, D. B. Fitzgerald, J. Zuanon, M. Arce, A. P. Gonçalves & M. Sabaj-Péres. GoogleMaps INPA-ICT 40614 , 1, 68.5 mm SL, Porto de Moz, 01°44’54”S 52°14’18”W, 23 Sep 2013, A. R. Martins, D. R. G. Ribeiro, R. R. Reyes, D. B. Fitzgerald, J. Zuanon, M. Arce, A. P. Gonçalves, M. Sabaj-Péres. GoogleMaps INPA-ICT 40739 , 10, 34.1–70.5 mm SL, Porto de Moz, 01°44’54”S 52°14’18”W, 25 Sep 2013, A. R. Martins, D. R. G. Ribeiro, R. R. Reyes, D. B. Fitzgerald, J. Zuanon, M. Arce, A. P. Gonçalves & M. Sabaj-Péres. GoogleMaps INPA-ICT 40747 , 18, 54.0– 90.3 mm SL, Porto de Moz, 01°44’54”S 52°14’18”W, 24 Sep 2013, A. R. Martins, D. R. G. Ribeiro, R. R. Reyes, D. B. Fitzgerald, J. Zuanon, M. Arce, A. P. Gonçalves & M. Sabaj-Péres. GoogleMaps INPA-ICT 40843 , 15, 31.8–66.0 mm SL, Anapu, 03°28’20”S 51°11’52”W, 1 Oct 2013, A. R. Martins, D. R. G. Ribeiro, R. R. Reyes, D. B. Fitzgerald, J. Zuanon, M. Arce, A. P. Gonçalves & M. Sabaj-Péres. GoogleMaps INPA-ICT 43082 , 4, 47.6–89.5 mm SL, Senador José Porfírio, 02°35’27”S 51°57’15”W, 27 Oct 2140, A. R. Martins, D. R. G. Ribeiro, R. R. Reyes, D. B. Fitzgerald, J. Zuanon, M. Arce, A. P. Gonçalves & M. Sabaj-Péres. GoogleMaps INPA-ICT 43152 , 1, 96.0 mm SL, Senador José Porfírio, 02°35’27”S 51°57’15”W, 3 Mar 2014, L. M. Sousa, M. Sabaj-Péres, A. S. Oliveira & P. M. Ito. GoogleMaps INPA-ICT 43213 , 7, 62.5–113.3 mm SL, Porto de Moz, 01°44’54”S 52°14’18”W, 4 Mar 2014, L. M. Sousa, D. Fitzgerald, A. S. Oliveira, P. M. Ito, N. Lujan, R. Robles, V. Vargas & M. Sabaj-Péres. GoogleMaps INPA-ICT 43249 , 7, 61.6–77.0 mm SL, Porto de Moz, 01°44’54”S 52°14’18”W, 5 Mar 2014, L. M. Sousa, D. Fitzgerald, A. S. Oliveira, P. M. Ito, N. Lujan, R. Robles, V. Vargas & M. Sabaj-Péres. GoogleMaps INPA-ICT 43260 , 8, 2.1–84.5 mm SL, Porto de Moz, 01°44’54”S 52°14’18”W, 5 Mar 2014, L. M. Sousa, D. Fitzgerald, A. S. Oliveira, P. M. Ito, N. Lujan, R. Robles, V. Vargas & M. Sabaj-Péres. GoogleMaps INPA-ICT 43295 , 3, 46.5-65.0 mm SL, Porto de Moz, 01°44’54”S 52°14’18”W, 6 Mar 2013, L. M. Sousa, D. Fitzgerald, A. S. Oliveira, P. M. Ito, N. Lujan, R. Robles, V. Vargas, M. Sabaj-Péres. GoogleMaps INPA-ICT 43334 , 2, 80.1–102.6 mm SL, Porto de Moz, 01°44’54”S 52°14’18”W, 7 Mar 2014, L. M. Sousa, D. Fitzgerald, A. S. Oliveira, P. M. Ito, N. Lujan, R. Robles, V. Vargas & M. Sabaj-Péres. GoogleMaps INPA-ICT 43546 , 2, 48.8–50.9 mm SL, Altamira, 03°12’12”S 52°12’23”W, 13 Mar 2014, L. M. Sousa, D. Fitzgerald, A. S. Oliveira, P. M. Ito, N. Lujan, R. Robles, V. Vargas & M. Sabaj-Péres. GoogleMaps INPA-ICT 43229 (same data as INPA-ICT 43213), 6, 70.8–107.0 mm SL, Porto de Moz, 01°44’54”S 52°14’18”W, 4 Mar 2014, L. M. Sousa, D. Fitzgerald, A. S. Oliveira, P. M. Ito, N. Lujan, R. Robles, V. Vargas & M. Sabaj-Péres. GoogleMaps LIA 0021 , 1, 61.4 mm SL, Belo Monte , 03°07’45”S 51°39’56”W, 28 Sep 2012, D. Bastos. GoogleMaps LIA 5098 , 5, 75.3–88.1 mm SL, rio Xingu , off right bank, ca. 1 km northwest of Porto do Moz, 01°44’42”S 52°14’54”W, 14 Nov 2014, M. H. Sabaj, L. M. Sousa & fishermen D. R. Costa (Dani), D. R. Costa (Ronca), N. S. Balão (Nelson) & A. S. Oliveira (Tonho). GoogleMaps LIA 5105 , 7, 75–113.9 mm SL, rio Xingu , off right bank, ca. 1 km northwest of Porto do Moz, 01°44’42”S 52°14’54”W, 14 Nov 2014, M. H. Sabaj, L. M. Sousa & fishermen D. R. Costa (Dani), D. R. Costa (Ronca), N. S. Balão (Nelson) & A. S. Oliveira (Tonho). GoogleMaps LIA 5118 , 2, 72.8–106.49 mm SL, rio Xingu , off right bank ca. 3 km north-northwest of Porto do Moz, 01°43’53”S 52°15’20”W, 14 Nov 2014, M. H. Sabaj, L. M. Sousa & fishermen D. R. Costa (Dani), D. R. Costa (Ronca), N. S. Balão (Nelson) & A. S. Oliveira (Tonho). GoogleMaps LIA 5122 , 2, 99.9 mm SL, rio Xingu , off right bank ca. 3 km north-northwest of Porto do Moz, 01°43’53”S 52°15’20”W, 14 Nov 2014, M. H. Sabaj, L. M. Sousa & fishermen D. R. Costa (Dani), D. R. Costa (Ronca), N. S. Balão (Nelson) & A. S. Oliveira (Tonho). GoogleMaps LIA 5146 , 19, 62.9–103.43 mm SL, rio Xingu , off upstream end of island, downstream of campsite 7, ca. 3.5 km northwest (downstream) of BR-230 ferry crossing on left bank ( Belo Monte II ), 03°06’19”S 51°43’28”W, 19 Nov 2014, M. H. Sabaj, L. M. Sousa & fishermen D. R. Costa (Dani), D. R. Costa (Ronca), N. S. Balão (Nelson) & A. S. Oliveira (Tonho). GoogleMaps LIA 5153 , 3, 34.2–67.37 mm SL, rio Xingu , off right bank at confluence of three major braids, just upstream of campsite 7, 03°07’45”S 51°39’55”W, 19 Nov 2014, M. H. Sabaj, L. M. Sousa & fishermen D. R. Costa (Dani), D. R. Costa (Ronca), N. S. Balão (Nelson) & A. S. Oliveira (Tonho). GoogleMaps LIA 5161 , 5, 62.3–80.2 mm SL, rio Xingu , off right bank ca. 20 km southeast of Vitória do Xingu, 02°58’51”S 51°51’32”W, 20 Nov 2014, M. H. Sabaj, L. M. Sousa & fishermen D. R. Costa (Dani), D. R. Costa (Ronca), N. S. Balão (Nelson) & A. S. Oliveira (Tonho). GoogleMaps LIA 6305 , 2, 46.7–51.1 mm SL, rio Xingu , rock pile in channel, 03°07’45”S 51°39’55”W, 29 Aug 2016, L. M. Sousa. GoogleMaps LIA 6863 , 5, 62.6–116.54 mm SL, Senador José Porfírio, Pedral in front of Itaubinha , 02°53’19”S 51°56’20”W, 8 Oct 2017, L. M. Sousa. GoogleMaps

Diagnosis. Hypancistrus seideli is distinguished from all congeners by its color pattern, having head, body and fins with alternating dark and pale vermiculations ( vs. tan background color with irregular brown blotches in H. yudja and small dark spots in H. phantasma ; dark background color with pale spots in H. contradens , H. inspector , H. lunaorum , H. margaritatus , and H. vandragti or with pale lines and spots in H. debilittera ; body with pattern of alternating light and dark broad wavy bars in H. furunculus ; and white background color with black straight stripes in H. zebra ). It can be further distinguished from H. debilittera by the number of bars on fins ( 6 to 10 in H. seideli and 3 to 4 in H. debilittera ).

Description. Morphometric and meristic data presented in Tab. 2 View TABLE 2 . Medium-sized loricariid, largest specimen measuring 117 mm SL. Body short and deep with deepest point at supra-occipital (17–36% SL), becoming gradually slender after dorsal fin base. Head deep, snout short. In lateral view, dorsal profile convex, rising as straight line from snout to nares, becoming gently curved from that point of the end of head, then gradually declining to the end of caudal peduncle. Ventral profile straight from snout tip to pelvic-fin insertion, then ascending gradually to insertion of first caudal-fin ray. Greatest width of body at cleithrum (29–36% SL). Head somewhat short (32–42% SL), without ridges or carinae.

Head and snout completely covered by plates with odontodes. Hypertrophied odontodes on cheek plates relatively few, completely exposed and partly set in depression anterodorsally to cleithrum. Eye large, laterodorsal; orbit round and distinctly elevated; dorsal rim of orbit surpassing level of dorsal most portion of frontal bones.

Parieto-supraoccipital process short, bearing a small dorsal crest and limited posteriorly by set of predorsal plates arranged as one disjunct pair, followed by one or two closely attached pairs plus one single plate immediately anterior to dorsal-fin spinelet.

Oral disk circular, lips almost completely covered with small round papillae (papillae larger on proximal region of lower lip); lips smooth near maxillae. Lower lip large but not reaching pectoral girdle. Maxillary barbel moderate, larger than orbital diameter, mostly free from lower lip. Premaxillary teeth thin, delicate and bifurcated; mesial cusp larger, lateral cusp reaching mid portion of mesial cusp. Premaxillary teeth 5–18, two to three times smaller than dentary teeth; tooth crown bright red. Dentary with fewer teeth than premaxillary (1–9), similar in shape but considerably more robust. Dentary tooth rows arranged in approx. 90°angle. Branchial opening small. Interbranchial distance 15–25% HL.

Lateral line with 19–25* plates, four* to five plates between dorsal and adipose fins, 8–11 plates (10*) between anal and caudal fins. Body not carinate or keeled. Caudal peduncle deep and covered by five series of plates. All body plates covered by strong odontodes. Ventral surface largely naked from snout to anal-fin insertion; pectoral, thoracic and pre-anal areas with few small, scattered plates bearing odontodes, especially on larger specimens. Single plate between urogenital opening and anal-fin insertion.

All fin rays supporting odontodes; odontodes more developed on first (undivided) ray. Origin of dorsal fin in anterior third of body, between pectoral and pelvic-fin insertions. Dorsal fin II+7*, short, composed of spinelet, spine, and seven soft, segmented, branched rays. Dorsal-fin spinelet triangular with functional locking mechanism. Dorsal-fin spine with small odontodes along its entire margin. Tip of adpressed dorsal-fin spine reaching preadipose plate; membrane between last dorsal-fin ray and body absent. Four* to five plates separating dorsal and adipose fins. Adipose fin well developed, its base containing 5–6 plates; preadipose plate present. Adipose fin with strong spine bearing small odontodes on its entire surface, its distal tip reaching first caudal-fin procurrent ray. Pectoral fin with spine and 6–7 soft, segmented, branched rays (I+6*–7). Tip of adpressed pectoral fin reaching proximal half of pelvic fin. Pelvic fin with first ray thickened and unbranched and 5–6 branched rays (i+5*–6). Pelvic-fin tip slightly surpassing posterior end of anal-fin base. Anal fin with i+3–5 rays (4*). Caudal fin lunate with i+13–14+i rays, the dorsal and ventralmost thickened, unbranched and bearing small odontodes; lower lobe slightly longer than upper lobe.

Color in alcohol. Body, head and fins with alternated dark and pale wavy lines. Number and shape of pale lines vary ontogenetically and geographically. In juveniles, the light lines are relatively thick, less wavy and sometimes interrupted, leaving a sequence of light blotches on the body. In large specimens the lines are thinner, more numerous and frequently collapsed, forming a reticulate or alveolar pattern. Individuals of a same population may exhibit highly variable patterns of vermiculation ( Fig. 6 View FIGURE 6 ). The frequency of these color types may vary along the longitudinal distribution of the species.

Color in life. Similar to color in alcohol but more contrasting, with pale lines varying from white to yellowish, sometimes even pinkish.

Sexual dimorphism. Hypancistrus seideli presents the same secondary sex characteristics described for H. yudja , with males presenting hypertrophied odontodes on cheeks, pectoral spine and all body plates. The males also have a slimmer body but grow larger than females, with head proportionally larger. Females present a rounder body in dorsal view (more noticeable in gravid individuals). Sex dimorphism in H. seideli was extensively discussed in Reis et al. (2022).

Geographical distribution. Hypancistrus seideli occurs throughout the lower Xingu channel from the extreme downstream portion of Volta Grande do Xingu to the river’s confluence with the rio Amazonas ( Fig. 3 View FIGURE 3 ). Populations of Hypancistrus resembling H. seideli are found in the downstream portion of other clearwater tributaries of rio Amazonas, and their taxonomic status remains under study.

Ecological notes. Hypancistrus seideli occupies the broadest range of habitats known for the genus. The known depth range varies from < 1 to 40 m, and the rocks they inhabit vary from granitoid boulders to sedimentary rocks ( e.g., sandstones) of all shapes and sizes ( Fig. 7 View FIGURE 7 ). They can occur in strong currents at the downstream end of Volta Grande do Xingu (Middle Xingu), as well as in slow-flowing conditions in the Lower Xingu mouth bay ( i.e., ria).

Remarks. Hypancistrus seideli is a difficult species to diagnose using traditional taxonomic criteria, including its (conspicuous) color pattern. Its phenotypic plasticity spans an astonishing array of color patterns, many of which are recognized and named as varieties in the aquarium trade. Some morphotypes are slender with elongated caudal-fin lobes ( e.g., L66) while other forms are stouter-bodied and with a somewhat truncated caudal fin ( e.g., L333). Several intermediate forms exist, each one with an individual L code number ( Haagensen, 2014).

Popular name. Acari-pão (Portuguese); King Tiger Pleco, Golden King Tiger, (English); L66, L236, L287, L333, L399, L400 (and perhaps some other L code numbers).

Etymology. A patronym honoring Ingo Seidel, a renowned German aquarist whose decades of dedication to the care, understanding, and breeding of Hypancistrus species in captivity have made him a global authority. Ingo’s vast contributions to the knowledge of Hypancistrus (and other loricariid genera) through numerous books and lectures have significantly advanced the aquarium hobby, particularly in the realm of pleco breeding. This species is named in recognition of his unwavering passion and invaluable contributions to the field.

Conservation status. Hypancistrus seideli is widespread throughout the entire Lower Xingu channel from the extreme downstream portion of Volta Grande do Xingu to the river’s confluence with the rio Amazonas. The species occupies slow moving stretches of the river and probably will not be negatively affected by the Belo Monte dam. Their adaptability is shown by the presence of an introduced population near the town of Altamira that became established after the release of captive specimens by aquarium fish traders some years ago. Populations of this species currently face no identified imminent threats, which would align with the Least Concern (LC) categorization, as per the criteria established by the International Union for Conservation of Nature (IUCN, 2022).