Phenacorhamdia cuspidata, Silva & Castro & Ohara & Oliveira, 2024

Silva, Gabriel S. C., Castro, Íthalo Da Silva, Ohara, Willian Massaharu & Oliveira, Claudio, 2024, A new species of Phenacorhamdia (Siluriformes: Heptapteridae) from the Juruena River basin, with insights into its phylogenetic position, Zootaxa 5555 (4), pp. 569-578 : 571-576

Phenacorhamdia cuspidata , new species

( Figs 1 , 2 ; Tab. 1 )

Phenacorhamdia sp. — Ohara WM, Loeb MV, 2016: 5, fig. 4 (Checklist of the upper Juruena River basin).

Phenacorhamdia sp. — Casatti et al. 2020: 6, tab. 2 (list of species).

Holotype. DZSJRP 22037, 55.3 mm SL, Brazil, Mato Grosso State, Juína, Juruena River, Tapajós River basin , 11º29’15.9”S 58º48’34.9”W, 31 may 2018, Brejão, G.

Paratypes. All from Brazil, Mato Grosso State, Juruena River, Tapajós River basin: DZSJRP 25011, 2, 20.7– 55.6 mm SL, (1 c&s, 48.8 mm SL), same data holotype. DZSJRP 22020, 3, 25.1–43.0 mm SL, Juína , 11º30’42.94”S 58º50’52.98”W, 30 may 2018, Brejão, G. DZSJRP 22061, 7, 20.3–55.3 mm SL, Juína , 11º32’6.9”S 58º43’1.9”W, 31 may 2018, Brejão, G. DZSJRP 22201, 2, 42.5–44.2 mm SL, Juína , 11º20’29.7”S 58º36’3.9”W, 01 sep 2018, Brejão, G. DZSJRP 22208, 1, 43.5 mm SL, Juína , 11º20’44.98”S 58º22’41.98”W, 03 jun 2018, Brejão, G. DZSJRP 22287, 3, 25.0– 42.7 mm SL, Juína , Juruena River , 11º20’51.9”S 58º44’30.9”W, 01 sep 2018, Brejão, G. DZSJRP 22415, 2, 37.8–40.3 mm SL, Cotriguaçu , 9º51’1.9”S 58º15’56.9”W, 08 jun 2018, Brejão, G. DZSJRP 22567, 7, 26.1– 39.9 mm SL, Cotriguaçu , 9º48’42.9”S 58º20’19.9”W, 10 jun 2018, Brejão, G. DZSJRP 22601, 3, 36.2–46.6 mm SL, Cotriguaçu , 9º6’55.9”S 58º27’59.9”W, 11 jun 2018, Brejão, G. DZSJRP 22624, 1, 42.0 mm SL, Cotrigaçu , 9 º06’59.0” S 58º28’45.0” W, 01 sep 2018, Brejão, G. LBP 30601, 1, 61.5 mm SL, Padronal , Mutum River , 13º5’8.7”S 59º53’00.3”W, 20 aug 2021, Reia, L., Silva, GSC., Souza, CS and Venturini. UFRO 22887, 7, 25.2–55.4 mm SL (2 c&s, 34.9–36.9 mm SL), Comodoro , Mutum River , 13°05’8,27”S 59°53’32.23”W, 27 jul 2013, Ohara, WM et al. MZUEL 7881, 2, 28.4–58.3 mm SL, Sapezal , Córrego Água Quente , 13º32’25.5”S 58º43’34.8”W, 30 aug 2013, Birindelli, J., Claro-Garcia, A., Assega, F. and Santana, E. MZUEL 9026 , 60.50 mm SL, Brasnorte , Norato River , tributary of the Sangue River , 7 km from Brasnorte, 12°11’12.9”S 57°59’33.3” W, 31 aug 2013, Birindelli, J., Claro-Garcia, A., Assega, F. and Santana, E. MZUEL 9027 , 1 , 28.83 mm SL, Sapezal , Calor River , tributary of the Papagaio River , 13°02’57.1”S 58°39’15.7”W, 31 aug 2013, Birindelli, J., Claro-Garcia, A., Assega, F. and Santana .

MZUEL 9117 , 5, 26.0– 38.22 mm SL, Brasnorte , Norato River, 12º11’12.9”S 57º59’33.3”W, 07 jul 2014, Birindelli, J., Claro-Garcia, A., Assega, F. and Santana, E .

Diagnosis. Phenacorhamdia cuspidata differs from all congeners, except Phenacorhamdia suia and P. taphorni by having multicuspid teeth (vs. conical teeth). The new species differs from the aforementioned species by having 48–52 vertebrae (vs. 39 in P. taphorni and 43–45 in P. suia ); pelvic-fin origin distinctly anterior to dorsal-fin origin (vs. pelvic-fin origin at vertical through dorsal-fin origin in P. taphorni ); body uniformly colored (vs. mottled colored body in P. suia ); pectoral fin with six branched rays (vs. seven in P. suia ; seven or eight in P. taphorni ). Additionally, P. cuspidata differs from all congeners by having the maxillary barbel not reaching pectoral-fin origin (vs. maxillary barbel surpassing the pectoral-fin origin in Phenacorhamdia cabocla , P. suia , P. somnians , P. roxoi , P. tenebrosa and P. tenius ; maxillary barbel reaching the end of adpressed pectoral fin in P. anisura , P. boliviana , P. hoehnei , and P. nigrolineata ; surpassing pectoral fin in P. provenzanoi and P. taphorni ; reaching pelvic-fin origin in P. macarenensis ). Additionally, the new species differs from some congeners by having the first pectoral-fin ray shorter than the second (vs. first pectoral-fin ray longer than the second, in P. anisura , P. macarenensis , P. provenzanoi , and P. taphorni ).

Description. Morphometric data are summarized in Table 1 . Small-sized Heptapteridae (maximum 61.5 mm SL). In dorsal view, body elongated, progressively more compressed from dorsal-fin base to caudal peduncle. Greatest body width at cleithral region, progressively narrowing anteriorly towards snout tip and posteriorly towards caudal fin. In lateral view, body depressed and concave profile from the snout tip end to supraoccipital end, convex from supraoccipital to dorsal-fin origin; straight from dorsal-fin origin to adipose-fin origin; straight and descending from adipose-fin origin to adipose-fin end; straight from adipose-fin end to caudal peduncle. In lateral view, ventral profile convex and descending from snout tip to opercular region; slightly convex from opercular region to pelvic-fin origin; straight from that point to anal-fin origin; slightly concave from that point to lower procurrent caudal-fin ray origin.

Head depressed, dorsally covered by skin with small papillae. Snout short and rounded in dorsal view. Subcutaneous eyes, dorsally positioned, and anterior of the midpoint of head. Mouth slightly superior (prognathous). Lower jaw slightly longer than upper visible in dorsal view. Premaxillary and dentary teeth arranged in a rectangular patch of several irregular rows. Distal portion of teeth flattened and multicuspid, with three to five aligned cusps. Maxillary barbel short, reaching the sensorial pore (po1+pm11) when adpressed to body. Outer mental barbel longer than inner barbel. Inner and outer mental barbels aligned each other. Outer mental barbels reaching posterior margin of branchiostegal membrane. Anterior and posterior nares tubular. Nares disposed in a squared arrangement. Posterior nares slightly closer to anterior ocular border than to anterior nares. Branchiostegal membranes free, supported by eight rays and joined to isthmus only at anterior point. Six (2 c&s) gill rakers along the anterior border of the first ceratobranchial.

Pectoral fin with one unbranched and six branched rays. First pectoral-fin ray shortest, second and third branched rays longest. Pelvic-fin origin anterior to dorsal-fin origin and with i,5 rays. Dorsal fin with i,6 rays. Dorsal-fin unbranched ray slightly convex. First basal radial inserted anterior to neural spine of 14 th− 16 th vertebra (2 c&s), and last basal radial anterior to the neural spine of 18 th −20 th vertebra (2 c&s). Adipose fin long (20.4−24.0% SL). Anal fin with vi,9 rays. Anal fin supported 12 distal radials, first inserted anterior to 28 th –30 th hemal spine and last inserted anterior to 34 th –36 th hemal spine. Precaudal vertebrae 17−21, caudal vertebrae 31−35, totaling 48−52 vertebrae (2 c&s). First hemal spine on 18 th vertebra. Hemal spine bifid. Eight ribs.

Caudal skeleton composed of a plate formed by parhypural + hypurals 1 and 2 in the lower lobe, upper lobe plate formed by hypurals 3 and 4 fused, hypural 5 free, and a pleurostile. Caudal fin forked with i,7+8,i principal rays. Caudal-fin lobes long, the ventral longer (23.7−34.2% SL) than dorsal lobe (18.5−26.1% SL). Thirteen to nineteen procurrent rays in dorsal and ventral lobes.

Laterosensory canal of the head with simple tubes ending in single pores. Supraorbital sensory canal usually with five branches and pores: s1, s2, s3, s6 and s8. Supraorbital pore 1 medially adjacent to anterior nares. Supraorbital s2 and infraorbital i2 fused (forming complex s2+i2) neared to anterior nares, s3 inside posterior nares, at the notch of the cutaneous membrane. s4, s5, pores absent. Pore s6 fused at midline of the cranium, opening in a single pore (s6+s6). The s8 at the posterior surface of the frontal. Infraorbital laterosensory canal with six branches pores: i1, i2, i3, i4, i5, and i6, with i2 fused to s2. Infraorbital pore i1 adjacent to anterior nares, between nares and maxillary barbel; i2+s2 neared to anterior nares. Pore i3 laterally positioned at midway between anterior and posterior nares; i4 at vertical through anterior orbit; i5 posterior to eye. Pore i6 located at vertical through at midway between pm8 and pm9. Preoperculomandibular canal with 12 lateral-line branches and pores: pm 1 in the medial portion of dentary; pm2, pm3, and pm4 aligned anteriorly to inner and outer mental barbel; pm5 dorsal to outer mental barbel base; pm6 just posterior to pm5; pm7 and pm8 at vertical through anterior and posterior orbit respectively. Four pores in the preopercle region: pm9, pm10, pm11+po1, and po2.

Color in alcohol. Background color of dorsal and lateral region of head and trunk light brown. Dorsal portion of head with a dense concentration of chromatophores extending from the anterior nostril to the base of supraoccipital process. Base of dorsal fin and caudal-fin lobes darkly colored. Ventral portion of head and body yellowish ( Fig. 1 ). Fin rays brownish, and interradial membranes hyaline.

Color in life. Very similar to preserved specimens, but with color of head and body vivid light brown ( Fig. 2 ) to very dark pigmentation.

Geographical distribution. Phenacorhamdia cuspidata is known from eleven localities in the Juruena River, upper Tapajós River basin ( Fig. 3 ).

Ecological notes. Phenacorhamdia cuspidata was collected in shallow, clear waters and fast-flowing currents, with sections of substrate of rocks and submerged aquatic vegetation ( Fig. 4 ).

Etymology. The specific epithet of Phenacorhamdia cuspidata is from the Latin cuspis, meaning pointed, and atus meaning make pointed, in allusion to the multicuspidate teeth in both premaxilla and dentary.

Phylogeny. Herein we using a 70% complete matrix of Heptapteridae with 952 loci and 12,892,627 bp. Our results found the same major clades identified in a recent phylogenomic study of Heptapteridae ( Silva et al., 2021) and confirmed the monophyly of Phenacorhamdia ( Fig. 5 ). Within Phenacorhamdia , our results recovered two main clades, the first composed by P. roxoi and P. tenebrosa , both from the Upper Paraná river basin, and the second clade composed by a couple of species of Phenacorhamdia from the Amazon River basin, where P. cuspidata is sister to a clade containing Phenacorhamdia sp.1 , P. suia , Phenacorhamdia sp.2 and P. somnians .

Figures

FIGURE 1. Phenacorhamdia cuspidata, DZSJRP 22037, holotype, 55.3 mm SL, Brazil, Mato Grosso State, Juína, Juruena River basin.

FIGURE 2. Phenacorhamdia cuspidata, paratype, MZUEL 7881, 58.3 mm SL, just after capture, showing its life coloration. Dorsal lobe of caudal fin damaged. Photographed by José Birindelli.

FIGURE 3. Geographic distribution of Phenacorhamdia cuspidata in Brazilian Shield. Black star: holotype; red circles: paratypes localities. One dot may represent more than one lot.

FIGURE 4. Habitat of Phenacorhamdia cuspidata, Mutum River, tributary of the upper Juruena River in Tapajós River basin.

FIGURE 5. Maximum likelihood tree of Heptapteridae, showing in detail the relationships among Phenacorhamdia species. Black nodes indicate 100% bootstrap values; gray nodes indicate nodal support between 99% and 85%.