Hypostomus leucophaeus, Zanata, Angela M. & Pitanga, Bruno R., 2016

Zanata, Angela M. & Pitanga, Bruno R., 2016, A new species of Hypostomus Lacépède, 1803 (Siluriformes: Loricariidae) from rio Itapicuru basin, Bahia State, Brazil, Zootaxa 4137 (2), pp. 223-232 : 224-231

Hypostomus leucophaeus , new species

Figs. 1–3

Holotype. MZUSP 119822, 131.2 mm SL, Brazil, Bahia, Rio Real, Fazenda Pau Ferro, rio Itapicuru, around 15 Km from Rio Real, 11°34’41’’S 38°00’26’’W, 87 m above sea level, 14 Nov 2015, A. Zanata, R. Burger & L. Oliveira.

Paratypes. All from Brazil, Bahia, rio Itapicuru basin. UFBA 2993, 9, 73.9–134.1 mm SL, Rio Real, Fazenda Pau Ferro, rio Itapicuru, around 15 km from Rio Real, 11°34’34.9’’S 38°01’24’’W, 87 m a.s.l, 4 Dec 2004, A. Zanata, P. Camelier & T. Sá. UFBA 3026, 9, 79.6-136.0 mm SL, Fazenda Pau Ferro, rio Itapicuru, around 15 km from Rio Real, 5 Dec 2004, A. Zanata, P. Camelier & T. Sá. UFBA 3027, 5, 111.3- 122.5 mm SL, Povoado Alegre, rio Itapicuru, around 10 km from Rio Real, 6 Dec 2004, A. Zanata, P. Camelier & T. Sá. UFBA 3251, 20, 48.2– 136.8 mm SL, Jacobina, rio Itapicuru-mirim at ponte Roncador, around 10 km from Jacobina, 11°12’22.3’’S 40°25’53’’W, 426 m a.s.l., 12 Jun 2005, A. Zanata, P. Camelier, J. Birindelli, O. Oyakawa, M. Geraldes & P. Moura. UFBA 3290, 5, 24.3–81.8 mm SL, Saúde, rio Paiaiá on roadway BA 131 between Saúde and Pindobaçú, 10°53’47.5’’S 40°24’16.2’’W, 449 m a.s.l., 13 Jun 2005, A. Zanata, P. Camelier, J. Birindelli, O. Oyakawa, M. Geraldes & P. Moura. UFBA 3540, 3, 61.7–107.1 mm SL, Itiúba, rio Jacurici, 10°40’46.6’’S 39°41’56.1’’W, 310 m a.s.l., 14 Jun 2005, A. Zanata, P. Camelier, J. Birindelli, O. Oyakawa, M. Geraldes & P. Moura. UFBA 6509, 15, 66.8–115.8 mm SL; MZUSP 90869, 8, 91.7–124.5 mm SL, Queimadas, rio Itapicuru right below Barragem Grande, 10°59’18’’S 39°40’9.1’’W, 271 m a.s.l., 15 Jun 2005, A. Zanata, P. Camelier, J. Birindelli, O. Oyakawa, M. Geraldes & P. Moura. UFBA 7184, 4, 66.4–96.6 mm SL, Nordestina, rio Itapicuru at dam close to Salinas do Rio, 10°56’24.4’’S 39°24’55.8’’W, 4 Oct 2012, R. Burger & A. Calor. UFBA 8103, 15, 66.3–132.2 mm SL, collected with holotype. UFBA 8122, 6, 109.6– 141.8 mm SL; MZUSP 119842, 5, 101.7– 158.2 mm SL, Conde, Fazenda Coqueiro, around 10 km from Altamira, rio Itapicuru, 11°43’8.3’’S 37°45’0.4’’W, 38 m a.s.l., 8 May 2016, A. Zanata, R. Burger & B. Pitanga.

Diagnosis. Hypostomus leucophaeus is distinguished from most congeners by having a roughly triangular patch of platelets on ventral surface of body, posterior half of body grayish or with inconspicuous dark spots, and lower caudal-fin lobe distinctly longer than upper lobe. Hypostomus leucophaeus differs from congeners known from rivers draining Bahia State by having dark spots over a light brown or grayish background, at least on anterior half of trunk, and seven branched dorsal-fin rays and (vs. light brown or yellowish spots on a dark background and 10–11 branched dorsal-fin rays in H. chrysostiktos ), one or two series of inconspicuous dark spots larger than pupil on interradial dorsal-fin membranes and caudal fin uniformly grayish or with inconspicuous dark spots (vs. two or three series of conspicuous dark spots smaller than pupil on the interradial membranes and various series of conspicuous dark spots on than caudal fin of H. brevicauda and H. wuchereri ), spots on head and anterior portion of trunk inconspicuous and smaller than pupil in addition to ventral surface of body with large and triangular plated area (vs. head and trunk covered by conspicuous large dark spots ranging from half to approximately one eye diameter and ventral surface of body naked or weakly covered by platelets in H. jaguar and H. unae ). Hypostomus leucophaeus further differs from other congeners occurring in rivers draining the northeastern Brazilian region to the north of Bahia State by having the ventral surface of the body with a roughly triangular patch of platelets, wider anteriorly and tapering gradually posteriorly, leaving large lateral areas naked and narrow patch of platelets reaching posterior to pelvic-fin base but not reaching anus, and absence of keels on trunk (vs. covered portions forming anterior rectangular area, continuing by narrow median longitudinal and wide area posterior to the pelvicfins insertion and presence of keels on trunk in H. carvalhoi (Miranda Ribeiro) , H. jaguribensis (Fowler) , H. papariae (Fowler) , and H. pusarum (Starks)) , and absence of dark bars on caudal fin (vs. presence in H. eptingi (Fowler) and H. nudiventris (Fowler)) .

From congeners known to occur in the rio São Francisco basin, Hypostomus leucophaeus further differs by having dark spots on a light brown or grayish ground color (vs. light spots against a dark background in H. alatus Castelnau and H. francisci (Lütken)) , robust body and absence of predorsal keels (vs. elongate body and at least three predorsal keels in H. subcarinatus Castelnau ), spots on anterior portion of trunk similar in size or slightly larger than those on head (vs. spots on trunk twice as large as those on head in H. lima (Lütken)) , and anterior portion of abdomen covered by platelets, continuing posteriorly through a narrow median patch and leaving large lateral naked areas (vs. ventral surface of body completely covered by platelets in H. garmani (Regan) , H. johnii (Steindachner) , and H. vaillanti (Steindachner)) . Hypostomus leucophaeus further differs from H. vaillanti by the absence of vermiculations on predorsal region (vs. presence) and from H. johnii by having narrow plated area posterior to pelvic-fin base (vs. presence of broad plated area posterior to pelvic-fin base) and lower number of teeth on premaxilla (21–83, mode =60 vs. 60–110, mode 84) and dentary (23–79, mode=62 vs. 65–115, mode = 87). Hypostomus leucophaeus further differs from H. scabriceps (Eigenmann & Eigenmann) , the only congener known from coastal drainages nearby to the south of Bahia State, by having posterior portion of abdomen mostly naked (vs. completely covered by platelets), absence of keels on trunk (vs. presence), and inconspicuous spotted pattern on body and fins (vs. well defined spotted pattern on body and fins).

Description. Standard length of examined specimens, 54.6 to 158.2 mm SL. Measurements in Table 1 . Dorsal profile of body convex from snout tip to the occipital process, somewhat convex to straight from that point to dorsal-fin origin, straight from that point to middle of caudal peduncle and somewhat concave from end of base of adipose-fin spine to origin of dorsalmost caudal-fin rays. Ventral profile of body straight to somewhat convex from snout tip to anal-fin base, straight from that point to caudal-fin base. Body relatively depressed; greatest body width at cleithral region, progressively tapering posteriorly; width at cleithral region greater than head depth. Greatest body depth at dorsal-fin origin, gradually tapering posteriorly to caudal peduncle. Caudal peduncle robust and slightly trapezoid in cross-section, flattened ventrally.

Head somewhat depressed, wide and rounded anteriorly. Head without keels. Posterior border of parietosupraoccipital with triangular process. A single plate bordering posterior margin of parieto-supraoccipital. Interorbital region straight, with lateral margins slightly elevated. Eyes relatively small, dorsolaterally situated. Dorsal flap of iris present. Mouth wide; internal surface and area anterior to dentary teeth covered by relatively small papillae. Median buccal papilla present (see Armbruster, 2003, fig. 3). Lips rounded, posterior lip not reaching transverse line between gill openings and without distinctly fringed margin. Inner surface of lips covered by papillae, except for smooth region right behind toothed portions of the dentary. Anteriormost papillae of upper lip rounded and small, followed by patch of larger and closely positioned papillae; anteriormost papillae of lower lip roundish and relatively large, followed by patch of smaller papillae; distal margins of lips with very small papillae. Papillae on lower lip slightly more spaced than on upper lip. Teeth long, bicuspid and curved inward distally; mesial cusp longer, approximately two times length of the lateral cusp and curved inward. Most specimens possess high number of elongate teeth on premaxilla and dentary, 50 or more on each ramus) overlapping each other distally; a few specimens possess low numbers of comparatively robust teeth (around 20 on each ramus), not overlapping each other distally. Premaxilla with 21–83 teeth (mode = 60) (holotype 55), dentary with 23–79 teeth (mode = 62; holotype 64). Contralateral premaxillary ramii forming relatively straight line or somewhat convex arch; contralateral dentary ramii forming concave arch facing mouth cavity. Maxillary barbel short, equal or shorter than orbital diameter.

Body covered with five lateral rows of moderately spinulous dermal plates. Head completely plated dorsally, except for small naked area on snout tip that continues ventrally to margin of upper lip and small areas around nares. Ornamentation of compound pterotic usually similar to remaining surface of head. Dorsal-fin base not covered by plates. Median series of plates bearing lateral-line canals. Dorsal series of plates starting posteriorly, at vertical through dorsal-fin origin, flattened between end of dorsal-fin base and adipose-fin spine. Ventral series of plates usually starting above or slightly posterior to origin of pelvic-fin base. Nineteen (1), 20(5), 21*(32), or 22(3) dorsal plates; 23(2), 24*(37) or 25(2) mid-dorsal plates; 24(2), 25(7) or 26*(27) median plates; 25(18), 26*(25) or 27(2) mid-ventral plates; 19 (1), 20(8), 21*(26) or 22(6) ventral plates; 11(1), 12(8) or 13*(25), or 14(1) plates between anal and caudal fins. Three predorsal plates; seven*(19) or eight (22) plates below dorsal-fin base; five (22) or six*(19) paired plates between dorsal and adipose fins. Aligned odontodes covering most of lateral plates, forming parallel to somewhat divergent rows usually more conspicuous on posterior half of body; odontodes slightly stronger on posterior borders of plates. Absence of keels on trunk plates. Odontodes on head usually smaller than ones on trunk and not forming rows. Ventral surface of head usually with small triangular patches of platelets close to the opercular apertures in larger specimens and mostly naked in specimens around 110.0 mm SL or smaller. Degree of covering of the abdominal surface increasing ontogenetically. Middle to large-sized specimens (around 130.0 mm SL or larger) usually with a roughly triangular patch of platelets, wider anteriorly and tapering gradually posteriorly, leaving large lateral naked areas around pelvic-fin insertions; narrow median patch of platelets reaching posterior to pelvic-fin base but not reaching anus. Small specimens (around 100.0 mm SL or smaller) with abdominal surface almost or completely naked ( Fig. 3 ).

Dorsal-fin II,7 (41), its origin situated on vertical anterior to pelvic-fin origin and approximately at mid-length of pectoral-fin spine. Tips of last dorsal-fin rays usually reaching anterior border of preadipose plate or, more rarely, the anterior border of adipose-fin spine. Margin of dorsal-fin slightly convex. Adipose-fin spine narrow, slightly curved ventrally. Pectoral-fin I,6 (41), its posterior margin straight; distal portion of pectoral-fin spine with odontodes distinctly larger and curved, more conspicuous on larger specimens. Tip of pectoral-fin spine reaching from first third to mid-length of pelvic-fin spine. Pectoral-fin spine resting on top of pelvic-fin when adpressed. Pelvic-fin I,5 (41), its posterior margin somewhat rounded to straight. Tip of pelvic-fin reaching first third of length of anal-fin spine. Anal-fin I,3(3) or I,4(38), its border slightly rounded and reaching fourth or fifth plate after its origin. Caudal-fin i,12,i (1), i,13,i(4)or i,14,i*(34), its posterior margin concave and its lower lobe distinctly longer than upper. All fin rays covered by odontodes, larger on the spines. Thirty one vertebrae (1).

Color in alcohol. Overall ground color of dorsal and lateral surface of head and body light brown or grayish ( Fig. 1 ). Head covered with small dark inconspicuous spots, forming a somewhat reticulate pattern in some specimens; diameter of spots around half of pupil diameter. Body usually with inconspicuous dark spots, similar in size or slightly larger than those on head; spots more or exclusively visible on anterior half of trunk and posterior half of trunk usually uniformly grayish. Ground color of fins light-brown to grayish. Dorsal fin with dark spots, distinctly larger and somewhat more conspicuous than those of head and body; spots usually distributed in one series in each interradial membrane, except in some larger specimens with two series; membranes with seven or eight spots on larger specimens, and three or four spots on smaller specimens. Spots over paired fins usually somewhat smaller than those of dorsal-fin, usually one series per interradial membrane in larger specimens and two series in smaller ones. Caudal fin uniformly grayish in some specimens or with inconspicuous dark spots, usually not organized in bars. Spots over anal and adipose fins small and inconspicuous, when present. Ventral surface of head and body whitish, usually without spots except by a few specimens with inconspicuous dark spots on area between pectoral fins.

Color in life. Color pattern of freshly collected specimens similar to that in preserved specimens, but with higher contrast between dark spots and light brown ground color ( Fig. 2 ).

Etymology. The specific epithet leucophaeus from the Latin, meaning ash-colored, dun. Used here in allusion to the faint spotted pattern and overall light brown to grayish body coloration of the species.

Distribution. The new species is known from rio Itapicuru basin, a drainage located in the northern portion of the Bahia State, Brazil. ( Fig. 4 ).

Habitat and ecological notes. Specimens of Hypostomus leucophaeus were captured in the rio Itapicuru ( Fig. 5 ) and its tributaries, in stretches of up to 50 m wide and 1.8 m deep, with rocky bottom, usually clear water, mild to fast water current, and at altitudes ranging from 38 to 449 meters above sea level. The headwaters of the rio Itapicuru are included in the Chapada Diamantina domain, where remnants of semi-deciduous seasonal forests and Campos Rupestre, and the lower coastal portion of the river is under humid climate and surrounded by remnants of Atlantic Forest. The remaining portions, about 80% including upper to middle sectors of the river basin, is inserted in the semiarid domain, with severe drought periods, intermittent flow in the river and its tributaries ( Mestrinho et al., 2007), and riparian vegetation dominated by pastures or areas of Caatinga. Hypostomus leucophaeus was collected mainly in the upper and lower portions of the basin. Most of the areas sampled were impacted by anthropic activities as construction of water reservoirs for cattle and human use. No congener occurs in the rio Itapicuru.

Remarks. Hypostomus leucophaeus possesses overall external morphology relatively similar to the congener H. johnii , sharing the body covered by inconspicuous dark spots and the lower caudal-fin lobe distinctly longer than upper lobe. Hypostomus johnii was described from the rio Puty ( Steindachner, 1877: 692; = rio Poti, Piauí, Brazil), a tributary of Rio Parnaíba and Rio Preto, the latter possibly a tributary of Rio São Francisco. Anyway, H.

leucophaeus is diagnosed from H. johnii by having area posterior to pelvic-fin base devoid of platelets or with narrow median stripe of platelets not reaching anus (vs. presence of broad plated area posterior to pelvic-fin base to anus), comparatively lower number of teeth on premaxilla (see Diagnosis), and caudal fin mostly uniformly colored, without conspicuous spots (vs. presence of spots on caudal fin sometimes forming vertical bars).

A recent study of the fish species distributions of the Northeastern Mata Atlântica freshwater ecoregion (NMAF ecoregion sensu Abell et al., 2008) and the fish fauna shared with adjacent ecoregions by Camelier and Zanata (2014), listed 21 species shared exclusively between the NMAF and the São Francisco ecoregion (without considering species that are widely distributed and taxonomically problematic species, such as Characidium spp., Hypostomus spp., Trichomycterus spp.). Most of the shared species occur in rivers of the northern portion of the NMAF, such as the rio Itapicuru and the rio Paraguaçu. According to the authors, of the 24 studied drainages, the rio Itapicuru basin has the greatest ichthyofaunal similarity to the rio São Francisco basin. Of the 21 species shared only between the two cited ecoregions, 13 occur in the rio Itapicuru basin and four of them occur exclusively in these two basins ( Curimatella lepidura (Eigenmann & Eigenmann) , Hyphessobrycon micropterus (Eigenmann) , Leporinus reinhardti Lütken , and Prochilodus costatus Valenciennes ), attesting to similarities at the species level between the two drainages. Although Hypostomus leucophaeus possesses similarities with congeners from rio São Francisco basin, particularly H. johnii , ongoing revisionary studies by the senior author (AMZ) reveals no shared species of Hypostomus between São Francisco basin and coastal rivers draining Bahia State. Hypostomus leucophaeus is the only species of the genus to occur in the rio Itapicuru basin and is apparently endemic to that basin.

Comparative material examined. All listed specimens are from Brazil and alcohol-preserved. Hypostomus affinis : MZUSP 51716, 2, 82.9–88.8 mm SL, Espírito Santo, rio Doce; MZUSP 94029, 1, 75.4 mm SL, Minas Gerais, rio Mucuri. UFBA 5041, 1, 170.6 mm SL, Bahia, rio Mucuri. Hypostomus alatus : UFBA 7842, 1, 287.9 mm SL, Alagoas, rio São Francisco. Hypostomus brevicauda : BMNH 1864.1.19.16–17, 2 syntypes,189.0- 196.1 mm SL, Bahia. Hypostomus chrysostiktos : UFBA 4292, 6 paratypes, 109.0– 134.4 mm SL, Bahia, rio Paraguaçu basin. Hypostomus francisci : UFBA 4191, 2, 264.4– 265.8 mm SL, Alagoas, rio São Francisco. Hypostomus jaguar : MZUSP 90870, holotype, 163.8 mm SL, Bahia, rio Paraguaçu; MZUSP 90870, 5 paratypes, 68.5–160.5 mm SL, Bahia, rio Paraguaçu; MZUSP 91653, 1 paratype, 128.1 mm SL, Bahia, rio Paraguaçu basin. Hypostomus lima : UFBA 2046, 1, 136.2 mm SL, Bahia, rio São Francisco basin. Hypostomus macrops : UFBA 6622, 3, 202.0– 288.0 mm SL, Alagoas, rio São Francisco. Hypostomus pusarum : UFBA 3824, 3, 84.2–107.9 mm SL, Rio Grande do Norte, rio Seridó. Hypostomus scabriceps : MZUSP 51752, 1, 73.2 mm SL, Espírito Santo, rio São Mateus basin. Hypostomus subcarinatus : UFBA 6360, 2, 127.8– 161.2 mm SL, Bahia, rio São Francisco. Hypostomus unae : BMNH 1862.11.23.12, 1 syntype, 104.7 mm SL, Bahia; UFBA 5257, 10, 113.0–183.0 mm SL, Bahia, rio das Almas; UFBA 5718, 7, 77.5–102.0 mm SL, Bahia, rio das Almas basin; UFBA 6993, 1, 136.5 mm SL, Bahia, rio Una. Hypostomus vailanti : UFBA 6099, 6, 52.8–120.0 mm SL, Bahia, rio São Francisco basin; UFBA 6565, 1, 185.0 mm SL, Bahia, rio São Francisco basin. Hypostomus wuchereri : BMNH 1863.3.27.15, 1 lectotype, 203.8 mm SL, Bahia; BMNH 1852.9.13.128, 1 lectotype, 127.3 mm SL, Bahia.

Figures

FIGURE 1. Hypostomus leucophaeus, holotype, MZUSP 119822, 131.2 mm SL, rio Itapicuru, Rio Real, Bahia, Brazil.

FIGURE 2. Hypostomus leucophaeus, paratype, MZUSP 119842, 158.2 mm SL, rio Itapicuru around 10 km from Altamira, Fazenda Coqueiro, Conde, Bahia, Brazil. Photographed alive.

FIGURE 3. Head and anterior portion of body in ventral view of Hypostomus leucophaeus, (a) MZUSP 119842, 158.2 mm SL, (b) MZUSP 119842, 132.9 mm SL, (c) MZUSP 119842, 100.4 mm SL, showing the variation of presence and arrangement of platelets.

FIGURE 4. Geographic distribution of Hypostomus leucophaeus (white dot for type locality).

FIGURE 5. Collection site of Hypostomus leucophaeus, rio Itapicuru, Fazenda Coqueiro, Conde, Bahia, Brazil.

Tables

TABLE 1. Morphometric data for Hypostomus leucophaeus, new species. N = 40; SD = standard deviation.

	Holotype	Range	Mean	SD
Total length in mm	173.8	110.9–197.4	-	-
Standard length in mm	131.2	81.8–158.2	-	-
Percents of standard length
Head length	32.4	31.8–35.6	33.3	0.9
Predorsal length	43.0	39.4–44.8	43.0	1.3
Interdorsal length	19.3	15.4–20.2	18.2	1.0
Pre-anal length	65.8	62.9–68.7	66.7	1.2
Thoracic length	23.5	21.6–26.3	23.7	1.0
Abdominal length	22.9	21.0–25.6	23.2	0.8
Caudal peduncle length	31.3	27.1–32.7	30.7	1.1
Caudal peduncle depth	10.4	9.6–11.1	10.3	0.4
Dorsal-fin spine length	25.4	23.4–31.1	26.6	2.1
Folded dorsal-fin length	38.9	36.4–43.2	39.7	1.4
Dorsal-fin base length	23.4	21.4–24.8	23.2	0.9
Anal-fin spine length	10.4	7.6–12.4	10.0	0.9
Anal-fin base length	3.5	2.5–4.1	3.2	0.4
Pectoral-fin spine length	31.0	29.1–34.4	31.3	1.2
Pelvic-fin spine length	22.9	22.3–27.7	24.9	1.2
Upper caudal-fin ray length	26.2	21.3–28.5	24.2	2.4
Lower caudal-fin ray length	31.3	28.6–37.3	32.2	2.2
Adipose-fin spine length	8.5	7.5–10.0	8.8	0.6
Body depth at dorsal origin	21.0	17.4–23.3	20.1	1.5
Cleithral width	30.3	29.5–33.4	30.7	0.8
Percents of head length
Head depth	56.5	52.4–60.5	55.7	2.0
Snout length	66.1	62.0–69.5	65.4	1.6
Snout-opercle length	76.9	71.8–80.0	75.9	1.7
Orbital diameter	14.1	12.2–16.7	14.8	1.2
Interorbital width	40.2	35.6–41.6	38.8	1.6
Mouth width	54.8	49.7–61.1	55.7	2.9
Mandibular ramus length	17.6	16.7–22.3	19.0	1.3
Premaxillary ramus length	17.9	16.0–21.3	19.0	1.2
Maxillary barbel length	11.8	6.9–13.7	10.7	1.7