Hypostomus delimai, Zawadzki & Oliveira & Debona, 2013

Zawadzki, Cláudio Henrique, Oliveira, Renildo Ribeiro de & Debona, Tiago, 2013, A new species of Hypostomus Lacépède, 1803 (Siluriformes: Loricariidae) from the rio Tocantins-Araguaia basin, Brazil, Neotropical Ichthyology 11 (1), pp. 73-80 : 74-77

Hypostomus delimai new species ( Figs. 1- 3 )

Holotype. INPA 6191, 235.2 mm SL, Brazil, Pará, Itupiranga , rio Tocantins, 05°07’29.6”S 49°18’44.4”W, 14 Nov 1980, INPA ichthyological staff.

Paratypes. Brazil: Pará State: ANSP 192612 , 1, 202.1 mm SL; INPA 35376, 3 , 162.7 -230.0 mm SL. ZUEC 7088, 200.7 mm SL ,

collected with holotype. INPA 2485 , 1, 175.4 mm SL, Tucuruí, rio Tocantins, 03°51’54.1”S 49°39’1.6”W, 31 Oct 1987, F. Martinho. INPA 6153 , 1, 247.2 mm SL, Itupiranga, lago Morateiro, rio Tocantins, 05°08’42.1”S 49°18’10.2”W, 4 Jul 1982, INPA ichthyological staff. INPA 6192 , 2 , 206.0 and 253.1 mm SL, Itupiranga, rio Tocantins, 05°09’59.5”S 49°20’1.0”W, 30 Jun 1980, INPA ichthyological staff. INPA 6193 , 4 , 103.9 -215.0 mm SL. MPEG 24021 , 1, 168.8 mm SL, Itupiranga , rio Tocantins, 05°05’26.3”S 49°20’13.9”W, 30 Jun 1980, INPA ichthyological staff. INPA 6195 , 1, 147.8 mm SL, Itupiranga, rio Tocantins, 05°05’26.3”S 49°20’13.9”W, 30 Jun 1981, M. Jégu. MZUSP 110815 , 1 , 207.0 mm SL, São Geraldo do Araguaia , rio Gameleira , at its mouth, tributary to rio Araguaia , 06°08’11”S 48º23’35”W, 4 May 2009, T. Debona & C. H. Zawadzki. Tocantins State: INPA 20029 , 1 , 118.0 mm SL, Caseara, Parque Estadual do Cantão , lago Volta Grande, rio Araguaia , 09°47’16”S 50°09’54.5”W, 18 May 2000, J. Zuanon, E. J. G. Ferreira, S. Amadio & G. M. Santos. INPA 20473 , 1, 167.1 mm SL, Caseara, Parque Estadual do Cantão , lago Perdidos, rio Araguaia , 09°42’59.9”S 50°08’14”W, 24 Feb 2000, J. Zuanon, E. J. G. Ferreira, S. Amadio & G. M. Santos. INPA 35376 , 3 , 162.7 -230.0 mm SL; and NUP 11015, 1, 204.3 mm SL, border of Ananás and São Geraldo do Araguaia (in the border of the States of Tocantins and Pará), rio Araguaia , 06°08’14”S 48°19’52”W, 9 Jul 2009, T. Debona. NUP 11016, 1, 176.7 mm SL, Araguanã, rio Lontra , tributary to rio Araguaia , 06º33’56”S 48º38’11”W, 8 May 2009, T. Debona & C. H. Zawadzki. NUP 11017, 1, 205.5 mm SL, Ananás, border of the States of Tocantins and Pará, rio Araguaia , 06°08’14”S 48°19’52”W, 8 May 2009, T. Debona & C. H. Zawadzki .

Diagnosis. The new species is distinguished from all other Hypostomus species, with exception of H. carinatus (Steindachner, 1881) , H. hoplonites Rapp Py-Daniel, 1988 , and H. watwata Hancock, 1828 , by the presence of five to eight (mode seven) predorsal plates limiting the posterior border of the supraoccipital bone ( Fig. 3 ) (vs. one to three plates). Hypostomus delimai differs from H. carinatus , H. hoplonites , and H. watwata by having pale spots against darker ground color on body and fins (vs. dark spots against lighter ground color).

Description. Based on holotype and 21 paratypes. Counts and measurements in Table 1 . Head broad and slightly compressed. Body width at cleithral region slightly greater than head depth and approximately equal to head length. Snout and anterior profile of head weakly rounded in dorsal view. Snout in lateral profile rising from horizontal at approximately 45º. Dorsal profile nearly straight rising from snout tip to interorbital area, then rising slightly convex to dorsal-fin origin; sloped downward from dorsal-fin origin to region of dorsal procurrent caudal-fin rays, then elevating again to caudal-fin origin. Caudal peduncle somewhat ellipsoid in cross-section, dorsally and ventrally flattened. Eye moderate in diameter (14.1-17.1% of HL), dorsolaterally positioned. Interorbital area wide and flat in frontal view. Mesethmoid forming inconspicuous median ridge on dorsal region of snout. Weak ridge on dorsal surface of head, from nares to upper margin of eyes, and from here to compound pterotic. Cheek plates with odontodes usually small, but sometimes distinctively larger on posterior border. Cleithral process deep in lateral view, usually deeper than longer, its upper border convex. Supraoccipital generally with conspicuous median ridge; with narrow and relatively long posterior process limited by five to eight (mode seven) predorsal plates. Plates limiting supraoccipital as part of complex arrangement of platelets ( Fig. 3 ). Dorsal and lateral surface of head and body covered with dermal plates, except for small unplated area on tip of snout and dorsal-fin base. Predorsal region flattened, with paired moderate ridges. Trunk covered by five lateral series of dermal plates. Dorsal series of plates keeled from dorsal-fin origin to adipose-fin origin, then weakly keeled until upper procurrent caudal-fin rays. Keeled plates of all series, except ventral, with longitudinal rows of odontodes clustered at middle of plates. Mid-dorsal series with longitudinal rows of odontodes complete. Median series bearing complete lateral line, complete row of hypertrophied odontodes. Mid-ventral series moderately bent, with slightly enlarged longitudinal rows of odontodes. Ventral series strongly flattened on anterior region of caudal peduncle, bent on posterior region, and without conspicuous hypertrophied odontodes.

Mouth moderate in size with enlarged central buccal papilla; buccal papilla with distal portion usually fringed. Lips wide and round. Outer edge of upper lips with odontodes. Lower lip far from reaching gill opening, its inner surface covered with numerous small papillae, larger proximally. Maxillary barbel moderate in size, slightly shorter than orbital diameter. Teeth slender, with elongated main cusp and smaller lateral cusp. Intermandibular tooth row angle approximately from 100° to 120°.

Lower surface of head totally covered by platelets except area just beneath lower lip. Pectoral bridge and abdomen totally covered by platelets except small area at base of left and right pelvic-fin unbranched rays, respectively.

Dorsal fin II,7; moderate in size; spine flexible; its border almost straight; posteriorly reaching spine of adipose fin. Adipose-fin spine well developed, curved inward, with distal tip usually reaching anteriormost dorsal procurrent ray. Pectoral fin I,6; spine not flexible, slightly curved, with rounded tip, and usually with hypertrophied odontodes, largest on distal portion in largest specimens; when adpressed almost reaching middle of pelvic-fin spine. Pelvic fin i,5; unbranched ray curved inward; when adpressed surpassing anal-fin unbranched-ray base; its border slightly rounded. Anal fin i,4; when adpressed, distal tip of posterior rays reaching seventh or eighth plate posterior to anal-fin origin. Caudal fin i,7+7,i; slightly emarginated, with ventral lobe equal to slightly longer than dorsal lobe.

Color in alcohol. Ground color of dorsal surface of head and body grayish-brown. Head, dorsum and flanks covered with many pale spots against darker background. Pale spots dense, small, close to each other and less numerous, larger and more distant to each other from compound pterotic to caudal peduncle ( Figs. 2 and 4 ). On flanks of some individuals pale spots with irregular format usually fused to each other, sometimes forming vermiculations ( Fig. 1 ). Ventral region of head and abdomen slightly lighter than dorsal region in specimens up to 100.0 mm SL, in larger specimens ventral region of body similar to dorsal region. Some larger specimens with upper and lower lip dark. Dorsal, pectoral, pelvic, anal and caudal fins dark brown with pale round spots mainly over rays. Adipose fin dark brown with pale spots sometimes fused along spine ( Figs. 1 and 5 ).

Color in life. Color pattern similar to that observed in preserved specimens, except body and fins exhibiting greenbrown background and tan spots with green tinge ( Fig. 2 ).

Distribution and habitat. The species was found only in middle stretches of the rio Tocantins-Araguaia basin ( Fig. 4 ). Records of the new species were done before the construction of Tucuruí dam in the rio Tocantins and in the rio Araguaia, in a habitat that soon will be flooded by the construction of the Santa Isabel dam. The rio Araguaia has about 2,627 km long, and its headwaters are located near the Emas National Park, southeast of the Goiás State, Brazil. The rio Araguaia flows northeast to a junction with the rio Tocantins near the town of São João do Araguaia in the State of Pará. These rivers have turbid water, rocky and sandy substrate, and variable remnant riparian vegetation. The new species was found cooccurring, with Squaliforma cf. emarginata (Valenciennes, 1840) , Hypostomus faveolus , Hypostomus cf. plecostomus (Linnaeus, 1758) , H. pyrineusi (Miranda Ribeiro, 1920) , and another putative undescribed species of Hypostomus .

Etymology. The specific epithet delimai is in honor of Flávio César Thadeo de Lima, Brazilian ichthyologist, due to his numerous contributions to Neotropical ichthyology.

Figures

Fig. 1. Hypostomus delimai new species, INPA 6191, holotype, 235.2 mm SL, in lateral, dorsal, and ventral views, Pará, Itupiranga, rio Tocantins, Tocantins State, Brazil.

Fig. 2. Lateral view of Hypostomus delimai, NUP 11016, paratype, 176.7 mm SL, from the rio Lontra, rioAraguaia basin, in the border of Pará and Tocantins States, Brazil. Photographed immediately after capture.

Fig. 3. Hypostomus delimai, INPA 2473, 167.1 mm SL, highlighting complex of platelets limiting supraoccipital and anterior portion of predorsal region. The skin of predorsal region was removed to evidence plate limits.

Fig. 4. Distribution of Hypostomus delimai new species (circle) and H. hoplonites Rapp Py-Daniel, 1988 (triangle). Black symbols represent type localities.

Fig. 5. Lateral view of preserved specimens of Hypostomus delimai NUP 11016, paratype, 176.7 mm SL (top); and H.hoplonites INPA31849, 225.0 mm SL (bottom).