Imparfinis munduruku, Castro & Wosiacki, 2019

Castro, Íthalo Da Silva & Wosiacki, Wolmar Benjamin, 2019, Anew species of Imparfinis Eigenmann & Norris, 1900 (Siluriformes: Heptapteridae) from the Tapajós basin, Brazil, Zootaxa 4701 (5), pp. 461-472 : 462-469

Imparfinis munduruku , new species

Figs. 1–4 ; Table 1

Imparfinis aff. hasemani Ohara et al. (2017) : 295, fig 1.

Holotype. MPEG 38784 , 34.0 mm SL, Brazil, Pará State , Jacareacanga Municipality , igarapé Bacabal , tributary of the Rio Tapajós, Vila de Penedo, Trilha MI 3, 5º36’40.4”S 57º7’16.6”W, N. Benone, 12 Dec 2012.

Paratypes. All from Brazil, Pará State, Rio Tapajós basin, Jacareacanga Municipality : MPEG 25158 , 1 , 35.48 mm SL, same data of holotype . MPEG 26514 , 2 (1 c&s), 34.3–35.0 mm SL, Vila de Penedo , Trilha MI 3, 5º36’40.4”S 57º7’16.6”W, N. Benone, Oct 2012 . MPEG 28530 , 1 , 29.7 mm SL, Vila Terra Preta , 5º36’9.81”S 57º18’10.8”W, Concremat Ambiental staff, 27 Aug 2013 . MPEG 28674 , 2 , 27.58–37.05 mm SL, Vila São Martins , 6º6’21.6”S 57º39’0.0”W, Concremat Ambiental staff, 05 Sep 2013 . MZUSP 116656 , 1 , 38.2 mm SL, Rio São Benedito near the mouth, drainage of Rio Teles Pires, 9º07’00.0”S 57º00’35.7”W, W. M. Ohara, 12 Jan 2015 .

Diagnosis. Imparfinis munduruku is distinguished from all its congeners, except I. guttatus , by having a conspicuous dark brown vertical W -shaped band at the base of caudal-fin rays (vs. absence) and by having a wide dark brown midlateral stripe from snout to end of caudal peduncle (vs. narrow dark brown midlateral stripe in I. cochabambae , I. hasemani , I. lineatus , I. mirini , I. nemacheir , and I. spurrellii ; or absent in I. borodini , I. longicaudus , and I. pristos ); orbital margin not free (vs. with margin free in I. cochabambae , I. guttatus , I. hasemani , I. lineatus , I. longicaudus , I. minutus , I. mirini , I. nemacheir , I. pijpersi , I. piperatus , I. spurrellii , I. timana , and I. usmai ); by the presence of 39 or 40 total vertebrae (vs. 33–38 in I. piperatus , I. pristos , I. pseudonemacheir , and I. stictonotus ; 41–54 in I. borodini , I. cochabambae , I. hollandi , I. lineatus , I. microps , I. minutus , I. spurrellii , and I. timana ); dark brown dorsal head (vs. pale dorsal head in I. guttatus , I. longicaudus , I. minutus , I. mishky , I. nemacheir , I. pijpersi , I. pristos , and I. pseudonemacheir ); and extremity of the maxillary barbels (29.5–37.9% SL) surpassing the distal margin of pectoral fin when adpressed (vs. not reaching the posterior margin of branchiostegal membrane in I. microps ; surpassing the origin of the last pelvic-fin ray in I. minutus ; surpassing the origin of the first pelvic fin-ray in I. piperatus ; and reaching the origin of anal-fin in I. stictonotus ). Imparfinis munduruku is distinguished from I. guttatus also by the presence of the ventral lobe of the caudal fin dark brown, and the inferior caudal-fin lobe hyaline and from I. hasemani by the presence of seven or eight pairs of pleural ribs (vs. five).

Description. Morphometric data in Table 1 ; see figure 1 for general aspect. Longest specimen 37.0 mm SL. Body moderately elongated, oval in cross section through dorsal-fin origin, depressed anteriorly and gradually compressed from dorsal fin to caudal fin. Body flat between tip of snout to region over eyes, occipital region slightly convex, flat from posterior of occipital to dorsal-fin origin, slightly concave from origin to end of dorsal-fin base, straight from this point to anterior margin of adipose fin, slightly ascending along caudal peduncle. Head slightly depressed, snout short and rounded anteriorly in dorsal view.

Mouth subterminal. Two pairs of nares forming approximately a square; distance between posterior nares slightly greater than between anterior nares. Maxillary barbels dark brown, when adpressed along body extends to the distal margin of pectoral fin. Outer mental barbels surpass pectoral-fin origin. Inner mental barbels reach border of branchiostegal membrane. Eyes diameter 13.5–16.0% HL and without free margin, dorsolaterally oriented, at near mid-length of head. Branchiostegal membranes free, with seven rays.

Pectoral fin triangular, with i,7 rays; first ray inserted ventral and immediately posterior to margin of operculum; first spine with proximal half thicker and hard, distal half flexible, shorter than second ray; first branched ray longest. Dorsal fin rounded, first ray spinelet, with i,6 rays; its origin anterior to vertical through pelvic-fin origin; first ray as long as first branched ray. Dorsal-fin pterygiophores seven; first pterygiophore inserting anterior to neural spine of the 10 th vertebra.

Pelvic fin triangular, slightly rounded distal margin, with i,5 rays. Adipose fin with 3.4–4.0% SL, rounded, short, its posterior lobe free, not confluent with caudal fin; its origin aligned vertically through anal-fin origin and 25 th or 26 th vertebral centrum.

Anal-fin short, with ii,7 (6*) or ii,8 (2) rays. Anal-fin pterygiophores nine; anal fin origin in relation to vertebral centrum aligned on 23 th (1) or 24 th (6*) vertebra.

Caudal fin forked ( Fig. 1 ); upper caudal lobe with i,8 (7*) or i,9 (1) rays and lower lobe with i,8 (3) or i,9 (5*) rays; lobes short and rounded, dorsal lobe slightly longer than ventral lobe (7*). Caudal skeleton: parhypural ossified, fused to complex centrum PU1+U1 at anterior portion; hypurals 1 and 2 co-ossified as one plate, fused to complex centrum PU1+U1 at anterior portion; hypurals 3 and 4 co-ossified as one plate, not fused to complex centrum PU1+U1 and not in contact with HU1+HU2; hypural 5 ossified as a distinct bone, not fused to complex centrum PU1+U1, in contact with HU3+HU4. Uroneural as strong ossified bone fused to complex centrum PU1+U1. Long epural present ( Fig. 2 ).

Total vertebrae 39 (6) or 40 (1*), precaudal vertebrae 14 and caudal vertebrae 25 (6) or 26 (1*). Pleural ribs seven (5*) or eight (2) pairs. Branchiostegal rays seven (7*). Anterior process at base of neural spines starting at 12 th caudal vertebra; anterior process at base of hemal spines starting at 15 th caudal vertebra. Anus approximately at mid-length of pelvic fin, closer to pelvic-fin base than anal-fin origin. Urogenital papilla separated from anus by distance approximately equivalent to length of papilla.

Supraorbital pore s1 medially adjacent to anterior nares; s2 midway between anterior and posterior nares; s3 likely associated to s4, forming compound s3+s4 at posterior nares, adjacent to its posterior margin, at notch of cutaneous membrane; s6 midway between eyes, contralateral branches connected in head midline, opening in a single pore; s7 posterior to orbital margin and between eyes; s8 posterior and far from eye. Infraorbital pore i1 likely associated to i2 forming compound i1 + i2 laterally adjacent to anterior nares, posterior to maxillary barbel base; i3 posterior to maxillary barbel base and posterior to nares; i4 and i5 posterior to ocular margin; i6 posterior to eye. Pterotic branch at posterolateral corner of pterotic. Preoperculomandibular pores pm1 to pm4 between lower lip and mental barbels base; pm4 and pm5 pores approximately at same level, as well as between pm5 and pm6; pm7 and pm8 at vertical through infraorbital pores i4 and i5. Preopercle with two pores, pm9 and pm10. Postotic pore po1 likely associated to pm11, forming compound po1+pm11; po2 and po3 at end of membranous branch dorsal to dorsoposterior portion of opercle ( Fig. 2 ). Lateral line branch running dorsolateral and posteriorly to head. Lateral line of body complete, reaching base of caudal fin-rays.

Color in alcohol. Body coloration composed of three distinct patterns: 1) Deep color of integument yellowish as in ventral region of head, pectoral girdle, abdomen and pelvic girdle; 2) deep clear brown layer on dorsal of head and dorsolateral surfaces of body; cheek, lower lip, base of inner barbel, full extent of outer and maxillary barbel, and opercular region with scattered brownish chromatophores; 3) superficial layer composed by four dark transverse bars along dorsal region: first after head, second and third at base of dorsal fin and fourth between dorsal and adipose fins; a thin dark mid-lateral stripe from posterior nostril to posterior margin of opercle, then, as a conspicuous stripe, from this point throughout the lateral extension of body to caudal-fin origin. Ventral region of mouth very pigmented. Pectoral, pelvic, dorsal and caudal-fin rays slightly pigmented. Dark pigmentation mostly concentrated at fins’s base. Adipose fin translucent. Caudal fin with a conspicuous dark vertical band W -shaped turned ahead, on base of its rays. Dark pigmentation mostly concentrated around base of fins.

Distribution and habitat. Imparfinis munduruku is known from tributaries of the Rio Tapajós, Jacareacanga Municipality, and Rio Teles Pires, in the southwest of State of Pará, Brazil ( Figs. 5–6 ). Ohara et al. (2017: 295) commented that I. munduruku (as Imparfinis aff. hasemani ) can be found in waters with sandy, rocky and leafy bottom, with individuals living solitary, not forming schools. However, the lots mentioned correspond to two sympatric species in the Rio Tapajós basin, I. munduruku and I. hasemani .

Etymology. The specific epithet is given in allusion to the indigenous tribe Munduruku, Cara Preta or also self-named Wuyjuyu, who traditionally inhabit the banks of the Rio Tapajós in southwest Pará (including the typelocality of the new species), northern Mato Grosso, and east Amazonas. A noun in apposition.

Conservation status. Imparfinis munduruku is reported from the Rio Tapajós near São Luis de Tapajós and Rio Teles Pires near São Manoel dam, from material obtained during the Environmental Impact Studies related to the licensing of dams in both rivers. The Rio Tapajós dam licensing was denied, so the dams were not built. Although the locality of the Rio Teles Pires has not been flooded, it is located about 8 km from the São Manoel dam and is still impacted by this hydroelectric plant. Considering the species is probably distributed along the 552 km course of both rivers between these locations, I. munduruku can be categorized as Least Concern (LC) according to IUCN criteria ( IUCN, 2019).

Figures

FIGURE 1. Imparfinis munduruku, MPEG 38784, holotype, 34.0 mm SL, from Brazil, Pará, Jacareacanga, Vila de Penedo, tributary of Rio Tapajós.

FIGURE 2. Caudal skeleton of Imparfinis munduruku, MPEG 26514, 35.0 mm SL, paratype.Abbreviations: CF, caudal artery foramen; EPU, epural; HU1+HU2, ventral hypural plate formed by coossification of hypurals 1 and 2; HA+HAS, complex hypurapophysis (hypurapophysis and secondary hypurapophysis fused); HU3+HU4, dorsal hypural plate formed by co-ossification of hypurals 3 and 4; HU5, hypural 5; PH, parhypural; PU1+U1, complex centrum composed of preural centrum 1 and ural centrum 1; PU2, preural centrum 2; UR, uroneural. Scale bar = 1 mm.

FIGURE 3. Cranium of Imparfinis munduruku, dorsal view, MPEG 26514, 35.0 mm SL, paratype.Abbreviations: AF, anterior fontanel;AN, antorbital; AP, autopalatine; AT, antorbital tubule; EP, epioccipital; ES, extrascapula; EX, exoccipital; FR, frontal; i1–6, infraorbital sensory branches 1 to 6; LE, lateral ethmoid; ME, mesethmoid; MX, maxilla; NA, nasal; PF, posterior fontanel; PRE, premaxilla; po1+pm11, postotic-preoperculomandibular complex sensory branch (postotic sensory branch 1+ preoperculomandibular sensory branch 11); po2, postotic sensory branch 2; PT, pterotic; s1–4, supraorbital sensory branches 1 to 4; s6, supraorbital sensory branch 6 (epiphyseal branch); s7, supraorbital sensory branch 7 (postorbital branch); s8, supraorbital sensory branch 8 (parietal branch); SP, sphenotic; ST1–4, suborbital tubules 1 to 4; SOC, supraoccipital; SOCP, supraoccipital process. Scale bar = 1 mm.

FIGURE 4. Imparfinis munduruku, MPEG 26514, 35.0 mm SL, paratype. Dorsal view of the branchial skeleton. Left superior branchial elements were removed. Abbreviations: ACN, accessory cartilaginous nodule; BB2-4, basibranchials 2 to 4; CB1-5, ceratobranchials 1 to 5; EB1-5, epibranchials 1 to 5; HB1-3, hypobranchials 1 to 3; PB3-4, pharyngobranchials 3 to 4; TP, tooth plate; UP, uncinate process. Scale bar = 1 mm.

FIGURE 5. Distribution of Imparfinis munduruku: black circle represent the type locality and white circles represent paratypes.

FIGURE 6. Igarapé Bacabal, type locality of Imparfinis munduruku, Rio Tapajós, Jacareacanga, Pará State, Brazil.

Tables

TABLE 1. Morphometric data for holotype and seven paratypes of Imparfinis munduruku. Abbreviations: n = number of specimens; SD = standard deviation.

		Holotype	n	Range	Mean	SD
1	Standard length (mm)	34.0	8	27.5–38.2	33.9	–
		Percentages of standard length
2	Body depth	11.0	8	11.6–16.0	13.1	1.9
3	Predorsal length	35.0	8	35.0–38.8	35.9	1.5
4	Dorsal-fin base	12.1	8	11.0–13.1	12.2	0.7
5	Dorsal fin to adipose-fin	16.1	8	13.1–18.5	16.4	1.7
6	Preadipose length	63.2	8	64.1–65.0	64.5	0.6
7	Adipose-fin length	20.6	8	21.1–23.6	22.2	1.0
8	Adipose-fin depth	4.1	8	3.4–4.0	3.8	0.2
9	Prepectoral length	20.8	8	16.5–23.4	20.4	2.6
10	Prepelvic length	39.7	8	40.0–42.7	41.1	1.1
11	Preanal length	63.9	8	62.8–67.2	65.2	1.4
12	Pectoral fin length	12.1	8	12.6–16.4	14.0	1.4
13	Dorsal-fin length	16.8	8	14.7–17.7	16.7	0.9
14	Pelvic-fin length	13.6	8	11.9–15.7	14.0	1.4
15	Anal-fin length	12.1	8	11.3–14.7	12.6	1.0
16	Anal-fin base	12.1	8	11.3–15.2	13.0	1.0
17	Caudal-peduncle length	21.6	8	20.4–22.7	21.6	0.8
18	Caudal-peduncle depth	9.5	8	6.9–8.6	8.0	0.8
19	Upper caudal-fin lobe length	18.1	8	19.4–21.8	20.4	1.2
20	Lower caudal-fin lobe length	18.5	7	18.8–20.8	19.3	0.8
21	Maxillary-barbel length	27.4	8	29.5–38.0	32.2	3.1
22	Outer mental-barbel length	18.9	8	18.3–24.3	19.9	2.1
23	Inner mental-barbel length	11.5	8	9.7–17.0	14.3	2.5
24	Head length	7.3	8	6.8–8.3	7.6	0.5
		Percentages of head length
25	Head width	67.2	8	68.6–78.2	73.8	3.7
26	Head depth	49.0	8	46.9–53.3	49.6	2.1
27	Snout length	35.0	8	33.6–48.5	39.1	4.2
28	Eye diameter	16.8	8	13.5–16.0	15.3	1.2
29	Fleshy interorbital	29.6	8	20.4–30.7	24.6	3.6
30	Mouth gape	55.7	8	40.1–53.1	48.3	5.4