Hypostomus robertsoni, Dias & Zawadzki, 2021

Dias, Angelica Corrêa & Zawadzki, Cláudio Henrique, 2021, Hypostomus hermanni redescription and a new species of Hypostomus (Siluriformes: Loricariidae) from Upper Paraná River basin, Brazil, Neotropical Ichthyology (e 200093) 19 (2), pp. 1-24 : 11-18

Hypostomus robertsoni , new species urn:lsid:zoobank.org:act:B2898D72-357C-43CC-AFD3-5965C06298F8

( Figs. 5–6 ; Tab. 3)

Hypostomus hermanni —Zawadzki et al., 2004:251 (allozymes). — Hypostomus sp. 2 Viana et al., 2013:222 (checklist). — Hypostomus sp. 1 Frota et al., 2016:6 (checklist; fig. 2k, p. 9). — Hypostomus aff. hermanni Kamei et al., 2017:2 (cytogenetic). — Hypostomus sp. 1 Dias, Zawadzki, 2018:394 (identification key; fig. 13, p. 408).

Holotype. NUP 22740, 127.9 mm SL; Brazil, Paraná State, Município de Marialva, Upper Paraná River basin, tributary of Ivaí River , Keller River , 23°38’28”S 51°51’31”W, 18 Aug 2014, C. H. Zawadzki, L. F. Pesenti, H. B. Ruiz & R. Vieira.

Paratypes. Brazil: state of Paraná: Upper Paraná River basin: Ivaí River basin: LBP 26253, 2, 108.1– 121.6 mm SL, Marialva , Keller River , 23°38’48”S 51°52’52”W, 8 Feb 2016, C. H. Zawadzki, G. C. Zawadzki, Luiz F. Pesenti & H. P. da Silva. LIRP 15555 , 3 , 91.4–102.4 mm SL, divise between Floresta and Engenheiro Beltrão, Ivaí River, 23°40’30”S 52°07’12”W, 16 May 2003, C. H. Zawadzki. MCNIP 3218 , 3 , 105.0– 110.2 mm SL; Marialva , Keller River , 23°38’48”S 51°52’52”W, 8 Feb 2016, C. H. Zawadzki, G. C. Zawadzki, L. F. Pesenti & H. P. da Silva. MZUEL 18886 , 3 , 90.2–102.9 mm SL; Marialva , Keller River , 23°38’48”S 51°52’52”W, 8 Feb 2016, C. H. Zawadzki, G. C. Zawadzki, L. F. Pesenti & H. P. da Silva. NUP 2597 , 34 , 58.4–147.5 mm SL (18, 84.3–135.7 mm SL), Município de Marialva , Keller River , 23°38’28”S 51°31’31”W, 10 Dec 1996, C. H. Zawadzki & H. F. Julio Jr. NUP 3744 , 37 , 58.7–119.4 mm SL (19, 93.5–119.4 mm SL), Marialva , Keller River , 23°38’25”S 51°51’32”W, 1 Mar 2005, C. H. Zawadzki & W. J. Graça. NUP 4842 , 27 , 89.8 –122.0 mm SL (16, 92.0– 121.6 mm SL), Floresta , Ivaí River , 23°42’01”S 52°07’02”W, 6 May 2003, C. H. Zawadzki. NUP 7062 , 1 , 89.4 mm SL; Campo Mourão , Mourão River , 24°02’23”S 52°16’22”W, 7 Apr 2009, C. H. Zawadzki, R. Ota, H. Message & L. Mommenshon. NUP 8535 , 1, 172.5 mm SL; Turvo, Pedrinho River , 25°46’44”S 51°25’35”W, 28 Feb 2009, D. Viana. NUP 8536 , 3 , 139.3 – 156.9 mm SL, Turvo, Bonito River , 24°45’30”S 51°24’49”W, 23 Feb 2009, D. Viana. NUP 17253 , 5 , 88.9–108.9 mm SL, Marialva, Keller River , 23°38’28”S 51°51’31”W, 15 Jun 2011, L. Mommenshon. NUP 17255 , 2 , 76.2–111.9 mm SL, Marialva, Keller River , 23°38’28”S 51°51’31”W, Jun 2011, H. B. Ruiz .

Non– types. Brazil, Paraná State, Upper Paraná River basin, Ivaí River basin. NUP 3031 , 29 , 70.5–89.8 mm SL; Campo Mourão , Mourão River , Ivaí River basin, 24°02’23”S 52°16’22”W, 19 Nov 2003, C. H. Zawadzki & V. S. Ferreira. NUP 3641 , 2 , 84.1–85.7 mm SL; Manoel Ribas, Água Fria River , 24°31’14”S 51°40’12”W, 24 Jan 2015, V. Hilhmann. NUP 4436 , 3 , 45.3–67.1 mm SL; Campo Mourão, do Campo, 23°59’22”S 52°20’00”W, 29 May 2006, C. H. Zawadzki & W. J. Graça. NUP 5806 , 7 , 32.7–56.9 mm SL; Marialva, Keller River , 23°38’30”S 51°51’33”W, 17 Apr 2008, C. H. Zawadzki, A. G. Bifi & H. V. Alcaraz. NUP 7078 , 3 , 63.2–81.2 mm SL; Ourizona, ribeirão Andirá, 23°22’02”S 52°11’42”W, 3 Apr 2009, C. H. Zawadzki, R. Ota, C. M. Oliveira & H. Message .

Diagnosis. Hypostomus robertsoni is distinguished from the species of the super-group H. cochliodon by having viliform teeth and dentaries usually angled more than 100° (vs. spoon- or shovel-shaped teeth and dentary rami angled to each other up to 80°; from the species of the super-group H. hemiurus by having round dark blotches (vs. somewhat horizontally elongate dark spots); from the species of the super-group H. plecostomus by lacking rows of odontodes on keels along lateral series of plates (vs. with moderate to well-developed rows of odontodes on keels); from H. nematopterus by lacking elongate dorsal-fin ray (vs. extremely elongate dorsal-fin ray). From the congeners of the H. auroguttatus super-group Hypostomus robertsoni is distinguished from H. alatus , H. albopunctatus , H. arecuta , H. faveolus , H. francisci , H. krishnamurtii , H. luteus , H. luteomaculatus , H. margaritifer , H. meleagris , H. microstomus , H. multidens , H. regani , H. roseopunctatus , H. scabriceps (Eigenmann & Eigenmann, 1888) , H. strigaticeps , H. tietensis and H. variipictus by having dark blotches on a clear background (vs. pale spots or vermiculations on a darker background); from H. asperatus , H. brevicauda , H. johnii , H. melanephelis Zawadzki, Oliveira, de Oliveira & Rapp Py-Daniel, 2015 , H. nigropunctatus , and H. uruguayensis by having faded dark blotches similar to or slightly larger than eye diameter on trunk and fins (vs. similar to eye pupil); from H. denticulatus , H. iheringii , H. macrops , H. latirostris , and H. ternetzi by having parieto-supraoccipital and predorsal region flat (vs. parieto-supraoccipital medially raised and with raised parallel keels on predorsal region); from H. brevis , H. fluviatilis , H. goyazensis , and H. topavae by having parieto-supraoccipital and predorsal region flat (vs. predorsal region high and convex in frontal view); from H. denticulatus , H. freirei , H. kuarup Zawadzki, Kullander & Lima, 2012 H. latirostris , H. mutucae , H. paulinus , and H. ternetzi by having tooth number less than 46 on each premaxillary or dentary (vs. more than 50); from H. agna , H. isbrueckeri , and H. luetkeni by having a single predorsal plate bordering parieto-supraoccipital (vs. two to three plates in H. luetkeni and three in H. agna and H. isbrueckeri ); from H. guajupia by having conspicuous blotches or marks on body and fins (vs. lacking conspicuous blotches or marks); from H. heraldoi by having pectoral-fin spine length smaller than pelvic-fin unbranched ray (vs. larger than); from H. nigromaculatus by having pectoral-fin spine slightly curved, with diameter almost homogeneous along its length (vs. curved club-shaped pectoral-fin spine); H. wuchereri by having abdomen plated in specimens about 100 mm SL (vs. abdomen mostly naked in specimens up to 150 mm SL); from H. garmani and H. lima by having triangular-shaped caudal peduncle, its lateral surface straigth (vs. oval-shaped caudal peduncle, its lateral surface convex); from H. guajupia by having abdominal area mostly naked, larger specimens with transverse row of platelets in cleithral region and medially along abdomen (vs. abdominal area densely plated, from pectoral girdle to anus); from H. hermanni by lacking or with inconspicuous dark (faded brown) blotches on body and fins (vs. usually having conspicuous black blotches), and by having truncate caudal fin (vs. emarginate).

Description. Morphometric and meristic data are presented in Tab. 3. Head broad and moderately depressed. Body width in cleithral region greater than head depth and approximately equal to head length. Snout and anterior profile of head rounded in dorsal view. Snout rising at approximately 30º from horizontal in lateral profile. Dorsal profile weakly convex and sloped upward from snout tip to interorbital region, and from that point to dorsal-fin origin; sloped downward from dorsal-fin origin to region just anterior of dorsal procurrent caudal-fin rays, then elevating again to caudal-fin insertion. Caudal peduncle elliptically compressed, slightly flattened ventrally. Eye large, dorsolaterally positioned. Interorbital space straight in frontal view; orbit barely raised. Mesethmoid forming inconspicuous median ridge on dorsal surface of snout to nares. Pair of inconspicuous ridge on dorsolateral surface of head, from lateral margins of nares to anterodorsal margin of eyes, and from that longitudinally and softly through superior portion of compound pterotic. Exposed surface of opercle of moderate size. Parieto-supraoccipital flat, with short posterior process and bordered by a large single plate. Dorsal and lateral surfaces of head and body covered with dermal plates, except for a small naked patch on tip of snout and at dorsal-fin base. Dermal plates with very weakly hypertrophied odontodes mostly on posterior border. Predorsal region lacking ridges. Body lateral surface with five longitudinal series of plates. Dorsal series of plates dorsally flattened from dorsal-fin base origin to adipose-fin posterior edge. Mid-dorsal and median series lacking keels. Median series bearing complete lateral-line pores. Mid-ventral series with first four to five plates bent, without keels, to caudal peduncle. Ventral series gently bent, without rows of odontodes.

Mouth short to moderate. Median buccal papilla moderately developed. Lips moderate in size, transversely oval. Outer edge of upper lip covered by odontodes. Lower lip not reaching gill openings line. Lower lip inner surface covered with numerous small papillae, larger proximally to dentary. Maxillary barbel short, similar in length to eye pupil diameter, or even shorter. Villiform bicuspid teeth. Teeth moderate to robust, with lanceolated main cusp and smaller pointed lateral cusp. Teeth crown ventrally arched in lateral view. Intermandibular tooth row angle about 120°.

Lower surface of head with plated area anteriorly to gill opening. Abdomen usually mostly naked in specimens up to 130 mm SL. Larger specimens with transverse row of platelets in cleithral region and medially along abdomen. Dorsal fin II,7; moderate in size; its distal border convex; when adpressed posterior rays usually reaching azygous plate of adipose fin; spine flexible. Adipose-fin spine short, inflexible, moderately curved, and backward oriented, with distal tip usually not reaching first dorsal procurrent caudal-fin ray. Pectoral fin I,6, its distal border straight; pectoral-fin spine inflexible, slightly curved with rounded tip, and usually with distally moderately developed hooklets, especially in larger specimens (i.e., about 150 mm SL; NUP 8536); when adpressed reaching about one-third pelvic-fin spine. Pelvic fin i,5 with anterior branched rays slightly larger than posterior ones; its distal border straight to slightly convex; pelvic-fin spine flexible, slightly curved inward; when adpressed surpassing anal-fin insertion. Anal fin i,4; when adpressed, distal tip of posterior rays reaching fifth to sixth plate posterior to its origin. Caudal fin i,7,7,i; truncate to slightly emarginate.

Color in alcohol. Dorsal surface of head and trunk dark, varying between brown to grey ( Fig. 5 ). Fins of the same color as body dorsal surface. Body surface usually without blotches; some juvenile specimens with inconspicuous dark blotches of similar size on head. Compound pterotic usually without blotches. Dorsal fin without blotches; interradial membrane with inconspicuous dark stripe anteriorly margin each branched ray. Few small specimens with inconspicuous blotches at the base of dorsal-fin posterior rays. Adipose and caudal fins without blotches. Pectoral and pelvic fins usually without blotches; few specimens with inconspicuous dark blotches on the proximal region of both fins. Saddles sometimes present, which may be the so-called “stress color” saddles ( Glaser, Glaser, 1995:63). Ventral region of body without blotches; whiter than dorsal region.

Color in life. Color in life similar to that on fixed specimens, but being more brown to grayish brown. Sometimes with faded dark blotches mainly on the dorsal region of head and trunk ( Fig. 6 ). Black pupil bordered by a golden yellow ring.

Sexual dimorphism. Not found.

Geographical distribution. Hypostomus robertsoni is only known from the Ivaí River basin ( Fig. 7 ). Specimens of the new species were found in some main tributaries as the Keller River ( Fig. 8 ), the type-locality, Bonito River, and Água Fria River.

Ecological notes. The Ivaí River basin can be geographically divided into three portions. The upper portion with steep slopes ranging from about 1200 to 600 m a.s.l. is a high gradient system; from this section, the median portion goes down to about 400 m a.s.l. having strong to moderate declivities; and finally, the lower section of this river is marked by a very low declivity (Parolin et al., 2010). Hypostomus robertsoni occurs syntopically with H. hermanni in this basin (e.g., NUP 4842). However, while H. hermanni is most frequently captured in the Ivaí River main channel, H. robertsoni commonly occurs either in the Ivaí River and in smaller tributaries.

Etymology. The specific epithet is in honor of Robertson Fonseca de Azevedo due to his large and constant efforts to preserve natural landscapes in the Paraná State, Brazil. Robertson faught to prevent unnecessary small hydroelectric power plants in the high gradient stretches along two main Upper Paraná River left tributaries, the Ivaí and Piquiri Rivers.

Conservation status. Hypostomus robertsoni is not abundant in scientific collections and does not present a wide distribution in the Upper Paraná River basin. Up to now, the species is only found in the Ivaí basin, however it is possible that it occurs in adjacent basins. Furthermore, there are no known imminent threats that would put the species at risk of extinction. Therefore, this species may be categorized as Least Concern (LC), according to the International Union for Conservation of Nature (IUCN) categories and criteria (IUCN Standards and Petitions Subcommittee, 2019).

Comparative material examined. All from Brazil. Paraguai River basin: Hypostomus latifrons : NUP 4369 , 5 , 43.3 –253.0 mm SL ; NUP 12206 , 7 , 92.6–174.8 mm SL ; NUP 12513 , 1 , 65.9 mm SL ; NUP 13413 , 1 , 80.4 mm SL ; NUP 13415 , 1 , 36.1 mm SL ; NUP 15063 , 2 , 40.8–147.3 mm SL ; NUP 17800 , 1, 104.5 mm SL. Hypostomus microstomus : MHNG 2367.90 , 1, 197.5 mm SL, holotype ; NUP 15173 , 1 , 78.3 mm SL. Hypostomus mutucae : MCP 28669 , 1 , 67.7 mm SL, holotype ; NUP 6641 , 13 , 52.4–109.2 mm SL ; NUP 6642 , 4 , 62.1–98.1 mm SL. Hypostomus peckoltoides : MZUSP 105226 , 1, 110.7 mm SL, holotype ; NUP 5216 , 2 , 88.9–92.8 mm SL, paratypes ; NUP 5217 , 3 , 85.5–98.2 mm SL, paratypes ; NUP 5218 , 3 , 80.7–86.4 mm SL, paratypes . Hypostomus renestoi : NUP 12339 , 1, 109.1 mm SL ; NUP 17796 , 1, 108.5 mm SL ; NUP 17798 , 2 , 82.4–99.4 mm SL. Hypostomus ternetzi : BMNH 1895.5 .17.64, 1, 210.2 mm SL, holotype . Paraná basin: Hypostomus albopunctatus : MZUSP 87176 , 2 , 120.5 – 154.8 mm SL ; NUP 16531 , 7 , 77.7–222.3 mm SL ; NUP 16137 , 28 , 42.4–139.4 mm SL. Hypostomus brevis : AMNH 7150 , 1 , 74.0 mm SL, holotype . Hypostomus denticulatus : MZUSP 98770 , 1, 161.9 mm SL, holotype ; NUP 4306 , 2 , 144.31 – 158.46 mm SL, paratypes ; NUP 5635 , 1, 156.6 mm SL, paratype ; NUP 5637 , 1, 120.1 mm SL, paratype . Hypostomus iheringii : NUP 2444 , 1, 100.9 mm SL ; NUP 9192 , 1 , 82.0 mm SL. Hypostomus margaritifer : BMNH 1907.7 .6.14, 1, 120.7 mm SL, holotype ; NUP 4041 , 2 , 131.3 – 161.1 mm SL ; NUP 10566 , 1, 142.2 mm SL ; NUP 13911 , 2 , 147.5 – 173.7 mm SL. Hypostomus meleagris : AMNH 12246 , 1, 252.8 mm SL, holotype . Hypostomus multidens : NUP 2561 , 5 , 96.3–155.4 mm SL, paratypes ; NUP 4821 , 2 , 160.0– 169.3 mm SL ; NUP 4829 , 1, 184.3 mm SL, paratype ; NUP 5340 , 1 , 157.0 mm SL, paratype ; NUP 6776 , 1 , 167.0 mm SL. Hypostomus nigromaculatus : MZUSP 22674 , 9 , 43.8–75.9 mm SL. Hypostomus paulinus : BMNH 1905.6 .9.4, 1, 135.0 mm SL, holotype . Hypostomus regani : BMNH 1905.6 .7.3, 1, 174.2 mm SL, holotype ; NUP 5601 , 5 , 138.4 – 209.4 mm SL ; NUP 6117 , 1 , 147.0 mm SL ; NUP 14225 , 2 , 136.9 – 150.1 mm SL. Hypostomus strigaticeps : BMNH 1907.7 .6.1012, 3, 75.7–160.0 mm SL, syntypes ; NUP 4017 , 2 , 72.8 –100.0 mm SL ; NUP 4538 , 11 , 82.0–140.0 mm SL. Hypostomus tietensis : BMNH 1905.6 .9.1, 1, 127.9 mm SL, holotype . Hypostomus topavae : NUP 2596 , 13 , 79.9–108.2 mm SL ; NUP 4458 , 4 , 65.9–102.9 mm SL ; NUP 4460 , 5 , 62.6–108.8 mm SL ; NUP 4529 , 12 , 49.9–116.4 mm SL ; NUP 4742 , 1 , 136.0 mm SL ; NUP 9630 , 11 , 29.1–118.5 mm SL ; NUP 13644 , 3 , 34.8–76.3 mm SL. Hypostomus variipictus : MZUSP 2114 , 1 , 289.0 mm SL, holotype . Hypostomus yaku : MNRJ 41722 , 3 , 28.3–50.2 mm SL, paratypes ; MZUSP 115072 , 3 , 24.0– 53.5 mm SL, paratypes ; NUP 15348 , 6 , 29.8–58.1 mm SL, paratypes . Hypostomus sp. : NUP 11769 , 1, 104.5 mm SL .

Figures

FIGURE 5 | Hypostomus robertsoni, holotype, NUP 22740, 127.9 mm SL; Brazil, Paraná State, Marialva, Keller River, tributary of Ivaí River, Upper Paraná River basin. Dorsal, lateral and ventral views.

FIGURE 6 | Specimens of Hypostomus robertsoni in life, with inconspicuous dorsal fin dark blotches.

FIGURE 7 | Distribution of Hypostomus hermanni (green triangle, type-locality, and orange circles) and H. robertsoni (red triangle, type-locality, and black circles) among Upper Paraná River basin. Some marks may represent more than one record.

FIGURE 8 | Keller River, tributary of Ivaí River, Upper Paraná River basin. Brazil, Paraná State, Marialva. Type-locality of Hypostomus robertsoni.