Hypostomus basilisko, Tencatt & Zawadzki & Froehlich, 2014

Tencatt, Luiz F. C., Zawadzki, Cláudio H. & Froehlich, Otávio, 2014, Two new species of the Hypostomus cochliodon group (Siluriformes: Loricariidae) from the rio Paraguay basin, with a redescription of Hypostomus cochliodon Kner, 1854, Neotropical Ichthyology 12 (3), pp. 585-602 : 590-597

Hypostomus basilisko , new species

Figs. 3b , 4b , 5b , 6b , 10 , 11 , 12

Holotype. MZUSP 111110, 182.5 mm SL, Brazil, Mato Grosso do Sul State, Bodoquena, córrego Salobrinha , rio Paraguay basin, 20°40’33"S 56°46’34"W, Mar 2007, O. Froehlich.

Paratypes. All from Brazil, Mato Grosso do Sul, Bodoquena , rio Paraguay basin (268 specimens) . CPUFMT 1448 , 1, 171.2 mm SL, rio Salobra , 20°46’49"S 56°44’31"W, Dec 2005, O. Froehlich . FMNH 108584 , 3 , 142.0-184.0 mm SL, córrego Salobrinha , 20°40’43"S 56°46’52"W, 7 Sep 1998, N. Menezes, J. Sabino, A. M. Zanata, M. Toledo-Piza & R. Lourival . INPA 37743 , 4 , 151.5 - 160.5 mm SL, córrego Salobrinha , 20°40’33"S 56°46’34"W, Mar 2007, O. Froehlich . MCP 47140 , 2 , 166.8 - 173.2 mm SL, rio Salobra , 20°46’49"S 56°44’31"W, Dec 2005, O. Froehlich . MNRJ 40184 , 4 , 143.5 -161.0 mm SL, córrego Salobrinha , 20°40’33"S 56°46’34"W, Mar 2007, O. Froehlich . MZUSP 59986 , 11 , 31.1-46.5 mm SL, córrego Salobrinha , 3-4 Mar 2002, N. Menezes, J. Sabino, A. Zanata & M. Toledo-Piza . MZUSP 111.128 , 5 , 111.5 -163.0 mm SL, córrego Salobrinha , 20°40’12"S 56°46’12"W, Mar 2007, O. Froehlich . NUP 5076 , 3 , 144.5 - 183.8 mm SL, rio Salobra , 20°29’44"S 56°51’48"W, 27 Dec 2006, A. G. Bifi . NUP 13832 , 1 c&s, 53.9 mm SL, rio Salobra , 20°29’44"S 56°51’48"W, 27 Dec 2006, A. G. Bifi . NUP 14503 , 1, 171.9 mm SL, rio Salobra , 20°46’49"S 56°44’31"W, 3 Sep 2005, O. Froehlich . NUP 14504 , 1,154.6 mm SL, córrego Salobrinha , 20°40’12"S 56°46’12"W, 31 Jul 2006, O. Froehlich . NUP 14505 , 7 , 37.5-165.9 mm SL, córrego Salobrinha , 20°40’12"S 56°46’12"W, Mar 2007, O. Froehlich . ZUFMS-PIS 1039 , 1 , 39.0 mm SL, rio Salobra , 13 Oct 2001, O. Froehlich . ZUFMS-PIS 1294 , 1 , 115.0 mm SL, córrego Salobrinha , 17 May 2001, O. Froehlich . ZUFMS-PIS 1460 , 3 , 42.5 - 53.0 mm SL, córrego Salobrinha , 9 Sep 2001, E. Amorim, J. Sedenho, M. R. Carvalho & L. P. C. Lopes . ZUFMS-PIS 1531 , 23 , 35.5 -65.0 mm SL, córrego Salobrinha , 18 Sep 2000, O. Froehlich . ZUFMS-PIS 1641 , 16 , 31.0- 68.5 mm SL, córrego Salobrinha , 20 May 2000, O. Froehlich . ZUFMS-PIS 1686 , 1, 168.7 mm SL, córrego Salobrinha , 20°40’12"S 56°46’12"W, 18 Sep 2000, O. Froehlich . ZUFMS-PIS 2491 , 13 , 145.0- 197.8 mm SL, rio Salobra, 20°46’49"S 56°44’31"W, 18 Dec 2005, O. Froehlich. ZUFMS- PIS 3082, 32, 20.3-113.5 mm SL, córrego Salobrinha , 20°40’12"S 56°46’12"W, Mar 2007, O. Froehlich . ZUFMS-PIS 3083 , 14 , 25.8-156.6 mm SL, córrego Salobrinha , 20°40’33"S 56°46’34"W, Mar 2007, O. Froehlich . ZUFMS-PIS 3084 , 24 , 34.0- 122.6 mm SL, córrego Salobrinha , 20°40’12"S 56°46’12"W, 31 Jul 2006, O. Froehlich . ZUFMS-PIS 3085 , 2 , 133.7 - 143.8 mm SL, córrego Salobrinha , 20°41’01"S 56°47’07"W, 23 Mar 2007, O. Froehlich . ZUFMS-PIS 2490 , 6 , 136.7 - 163.1 mm SL, córrego Salobrinha , 20°41’09"S 56°47’00"W, 15 Dec 2005, O. Froehlich . ZUFMS-PIS 3086 , 4 , 148.1 - 170.3 mm SL, córrego Salobrinha , 20°40’35"S 56°46’12"W, 16 Jul 2011, O. Froehlich . ZUFMS-PIS 3088 , 4 , 130.6 - 175.4 mm SL, córrego Salobrinha , 20°40’59"S 56°47’12"W, 26 Jul 2006, O. Froehlich . ZUFMS-PIS 3089 , 17 , 74.7-171.9 mm SL, córrego Salobrinha , 20°41’09"S 56°46’53"W, 29 Jul 2006, O. Froehlich . ZUFMS-PIS 3090 , 1, 163.7 mm SL, rio Salobra , 20°46’49"S 56°44’31"W, 10 Aug 2008, O. Froehlich . ZUFMS-PIS 3091 , 26 , 36.1-165.3 mm SL, córrego Salobrinha , 20°40’59"S 56°47’12"W, Jul 2006, O. Froehlich . ZUFMS-PIS 3092 , 38 , 37.1 -165.0 mm SL, córrego Salobrinha , 20°40’23"S 56°46’25"W, Mar 2007, O. Froehlich .

Diagnosis. Hypostomus basilisko is distinguished from all other Hypostomus species, except those belonging to the H. cochliodon group, by having the following unique combination of features: notch between metapterygoid and hyomandibula absent (vs. notch present) and strongly angled dentaries, less than 80° (vs. shallow angle between dentaries, generally more than 80°). It is distinguished from the other species of H. cochliodon group, except H. pagei Armbruster and H. soniae , by the absence of spots on body and fins (vs. spots present). Hypostomus basilisko can be distinguished from H. pagei by having highly developed keels on lateral series of plates (vs. keels weak, almost absent); from H. soniae for having teeth with a large spoon-shaped mesial cusp and a lateral cusp, if present, almost imperceptible (vs. teeth with mesial cusp conspicuously enlarged and rounded but not spoon shaped; distinct lateral cusp) and massive odontodes covering the dorsal region of head and trunk, forming well-developed keels (vs. less developed odontodes on head and trunk, keels absent or weakly-developed). It also differs from H. soniae by having many well-developed papilla on the internal surface of anterior and posterior jaws (vs. few papillae on the internal surface of anterior and posterior jaws). The new species can be additionally distinguished from H. cochliodon and H. khimaera by the lower number of vertebrae (27 vs. 29 and 28, respectively); from H. hondae (Regan) and H. plecostomoides (Eigenmann) by the absence of platelets in the skin around dorsal-fin base (vs. presence of platelets in the skin around dorsal-fin base); from H. levis by the presence of an adipose fin (vs. absence); from H. taphorni by having both caudal-fin lobes evenly colored (vs. bicolored caudal fin with ventral lobe darker).

Description. Morphometric data in Table 1. Overall view of body in Fig. 10 , juvenile in Fig. 4b . Head broad, deep and slightly compressed. Snout and anterior profile of head pointed to slightly round in dorsal view. Eye large, laterally positioned. Dorsal margin of orbit raised. Greatest body width at cleithrum, decreasing to caudal peduncle. Dorsal profile of head straight from snout tip to vertical through interorbital region, and forming 45° with ventral region of head; convex from that point to dorsal-fin origin; sloped downward to first dorsal caudal-fin

Tabela 1. Morphometric data of Hypostomus basilisko , H. cochliodon and H. khimaera . S.D.= standard deviation and n = number of measured specimens.

procurrent rays, then elevating again to caudal-fin insertion. Ventral profile almost straight from snout tip to insertion of pelvic-fin unbranched ray; slightly straight from pelvic-fin insertion to first ventral caudal-fin procurrent ray, then descending to caudal-fin insertion. Caudal peduncle laterally compressed, hexagonal on anterior region to very compressed on posterior region. Body dorsally covered with spinulose dermal plates, except on dorsal-fin base and small naked area on snout tip. Mesethmoid region densely covered by odontodes. Supraoccipital bone with highly developed median ridge; with short posterior process bordered by single plate. Conspicuous ridge originating laterally to nares, passing through supraorbital and extending through superior portion of compound pterotic.Exposed region of opercle large, ellipsoid and usually covered with several odontodes; odontodes more developed distally. Opercle completely surrounded by depression of thin skin layer ( Fig. 3b ). Oral disk round, moderate in size, lower lip not reaching vertical through gill openings ( Fig. 5b ); ventral surface covered with numerous small papillae decreasing in size posteriorly. Maxillary barbel slightly smaller than eye pupil. Odontodes present over anterior surface of upper lip, just anterior to snout. Buccal papilla (sensu Armbruster, 2003) absent. Dentaries acutely angled, averaging less than 80° between left and right dentary rami. Ten to 13 teeth (mode 10*), ten to 13 teeth in dentary (mode 12, holotype 11). Bicuspid teeth with mesial cusp massive and round; spoon shaped; lateral cusp very reduced or fused to mesial cusp. Juveniles, up to 80 mm SL, with viliform bicuspid teeth, similar to those in general species of Hypostomus (see Armbruster, 2003, fig. 1c). Inner portion of anterior and posterior jaws supporting agglomerated well-developed papillae, usually more developed on inner posterior jaws ( Fig. 5b ).

Body dorsally covered with five rows of spinulose dermal plates, except on base of dorsal fin and small naked area on snout tip. Odontodes more developed on whole head surface; conical in shape. Predorsal region medially keeled; area between keels concave. These keels, which support hypertrophied odontodes, slightly diverge posteriorly ( Fig. 6b ). Dorsal and mid-dorsal series of plates with keels also supporting hypertrophied conical odontodes. Median series bearing lateral line and without keels; most plates support medially aligned slightly hypertrophied odontodes. Mid-ventral series highly angled to sixth or seventh plate, without keel posteriorly.Ventral series slightly bent ventrally on caudal peduncle.Ventral surface of head covered with platelets, except beneath lower lip. Abdomen covered with minute platelets in specimens larger than 80 mm SL, except for very small areas around pectoral- and pelvic-fin insertions and at urogenital opening. Preanal plate present. Median series of plates with 27-28* (mode 28), three predorsal plates, plates between dorsal and adipose fins 7-8* (mode 8), plates between adipose and caudal fins 7-8* (mode 8) and plates below dorsal-fin base 7.

Dorsal fin II,7, its origin at vertical through midpoint between pectoral and pelvic fins, or slightly posterior to that point. Dorsal-fin distal margin straight; dorsal-fin posterior rays not reaching adipose spine. Adipose-fin spine compressed and curved inward. Pectoral fin I,6, its distal border straight. Pectoral-fin spine slightly curved inward, covered with moderately developed odontodes, slightly more developed on its distal portion in larger specimens. Tip of adpressed pectoral fin reaching one-third of adpressed pelvic-fin spine. Pelvic fin i,5, its distal border straight to slightly convex; its adpressed unbranched ray surpassing anal-fin origin. Anal fin i,4, its tip reaching fifth to sixth plate after its origin. Rays of anal fin progressively increasing in size, third branched ray generally longer. Caudal-fin margin falcate, i,14,i, with ventral lobe slightly longer than dorsal one.

Color in alcohol. Ground color brown yellowish to brown reddish. Region between mid-dorsal and mid-ventral keels with faint tan stripe, more evident below dorsal-fin base. Fins lighter and slightly more reddish than trunk. Region around base of dorsal fin darker. Darker coloration around dorsal-fin base extends medially along dorsal portion of caudal peduncle, forming inconspicuous stripe on dorsal profile in some specimens. Spots on body, head or fins absent.

Color in life. Ground color of body reddish brown with faint tan stripe between mid-dorsal and mid-ventral keels in most specimens, with stripe more evident below dorsal-fin base ( Fig. 11a ); or yellowish brown overall in other specimens ( Fig. 11b ). Spots absent on trunk, head or fins. Fins lighter than trunk. Eye color golden with black pupil.

Sexual dimorphism. Males with middle region of pelvic-fin spine thickened on ventral surface ( Fig. 12 ).

Distribution. Hypostomus basilisko is known from rio Salobra basin of the rio Paraguay basin, Bodoquena Plateau, Mato Grosso do Sul, Brazil ( Fig. 9 ).

Ecological notes. Hypostomus basilisko was collected and observed while snorkeling in clear-water streams and rivers of the Bodoquena Plateau. Larger individuals were easily observed during the day, lying on soft-bottom patches (mainly on sand, sometimes on leaf litter) at deeper sites. Those individuals foraged mainly during the night, when they sought shallower areas with rocky bottom. Occasionally, they were seen grazing during the day. Small individuals were observed foraging during the day and night, always in shallower areas.

Although, Hypostomus basilisko is part of a group of species that are usually reported as wood-eaters, individuals were observed foraging mainly on rocky substrates, as a periphyton grazer. Individuals also explored submerged logs and branches, but not to a noticeably greater extent than other species of Loricariidae that coexist with H. basilisko . The high degree of tooth abrasion that is usually observed in this species seems to support the idea that it does not use wood as its main food source.

Etymology. The Basilisk (from the Greek, basilisko ς [= basiliskos], diminutive of basileu ς [= basileus], meaning “little king”) is a mythical creature known as the king of snakes, which is often represented with a crown on his head. This crown makes an allusion to the three strong ridges at the top of head of the new species. A noun in apposition.

Remarks. The most conspicuous characteristics used to recognize Hypostomus basilisko are its overall reddish brown color pattern that lacks spots, the rough and spiny body odontodes, and the conspicuous keels. Until now, the only species of the H. cochliodon group totally lacking spots is H. soniae and some specimens of H. pagei Armbruster. In fact, H. soniae is the most similar species to H. basilisko . However the new species is differentiated from H. soniae by having large spoon-shaped teeth, with the lateral cusp, when present, almost imperceptible versus bicuspid non spoon-shaped teeth, with mesial cusp larger than lateral cusp, but with the lateral one being clearly visible in H. basilisko . Another remarkable feature of H. basilisko is the presence of hypertrophied odontodes, which are conspicuous all over the body and even more remarkable on anterodorsal region of body in specimens up to 150.0 mm SL.

Figures

Fig. 3. Opercle morphology of (a) Hypostomus cochliodon, NUP 10809, 215.8 mm SL, showing indistinct opercle without odontodes; (b) Hypostomus basilisko, holotype, MZUSP 111110, 182.5 mm SL and (c) Hypostomus khimaera, holotype, MZUSP 111129, 139.1 mm SL, showing layer of skin surrounding opercle that supports odontodes.

Fig. 4. Lateral view of juvenile in (a) Hypostomus cochliodon, NUP 11956, 92.8 mm SL, (b) Hypostomus basilisko, paratype, ZUFMS-PIS 3083, 64.2 mm SL and (c) Hypostomus khimaera, NUP13494,68.8 mmSL.

Fig. 5. Mouth and teeth of (a) Hypostomus cochliodon, NUP 10807, 208.0 mm SL, showing one series of papillae in inner face of upper and lower jaws; (b) Hypostomus basilisko, holotype, MZUSP 111110, 182.5 mm SL, showing the agglomerated papillae on inner face of upper and lower jaws; and (c) Hypostomus khimaera, MZUSP 111129, holotype, 139.1 mm SL, showing weakly developed papillae not forming series.

Fig. 6. Keels, ridges and odontodes of (a) Hypostomus cochliodon, NUP 10807, 208.0 mm SL, showing two weakly developed ridges in compound pterotic, weakly developed keels, few and weakly developed odontodes and predorsal keels weakly developed; (b) Hypostomus basilisko, holotype, MZUSP 111110, 182.5 mm SL, showing the three ridges on top of head, strongly developed keels, numerous welldeveloped odontodes on plates covering body and head and strong V-shaped predorsal keels; (c) Hypostomus khimaera, holotype, MZUSP 111129, 139.1 mm SL, showing moderately developed keels and dermal plates supporting moderately developed odontodes.

Fig. 10. Hypostomus basilisko, holotype, MZUSP 111110, 182.5 mm SL, córrego Salobrinha, rio Paraguay basin, Mato Grosso do Sul, Brazil; dorsal (top), lateral (middle), and ventral (bottom) views.

Fig. 11. Color pattern of live specimens of Hypostomus basilisko, paratypes (a) ZUFMS-PIS 3086, 150.5 mm SL, showing reddish-brown pattern; (b) ZUFMS-PIS 3086, 150.0 mm SL, showing yellowish-brown pattern.

Fig. 12. Sexual dimorphism of Hypostomus basilisko; (a) MNRJ 40184, paratype, 162.3 mm SL, showing pelvic-fin spine with no tumescence in adult female; (b) MNRJ 40184, paratype, 149.1 mm SL, showing a weakly developed tumescence (indicated by arrow) in juvenile male; (c) MZUSP 111110, holotype, 182.5 mm SL, showing well-developed tumescence (indicated by arrow) in adult male.

Fig. 9. Type locality of Hypostomus basilisko (yellow star), Hypostomus cochliodon (dark star) and Hypostomus khimaera (red star). The dark triangles represent areas of co-occurrence of Hypostomus cochliodon and Hypostomus khimaera; dark diamonds represent area of occurrence of Hypostomus cochliodon in the upper rio Paraná basin.