Creagrutus nigrotaeniatus, Dagosta, Fernando Cesar Paiva & Pastana, Murilo Nogueira De Lima, 2014

Dagosta, Fernando Cesar Paiva & Pastana, Murilo Nogueira De Lima, 2014, New species of Creagrutus Günther (Characiformes: Characidae) from rio Tapajós basin, Brazil, with comments on its phylogenetic position, Zootaxa 3765 (6), pp. 571-582 : 572-576

Creagrutus nigrotaeniatus , new species

(Figure 1; Table 1 )

Holotype. LIRP 8967 (1, 43.1 mm SL), Brazil, Mato Grosso State, Sapezal Municipality, rio Juruena, Bacia do rio Tapajós, c. 12°50’59’’S 58°55’36’’W, Aug 2010, col. Rodrigo Ilário.

Paratypes. (3 specimens). All from Brazil, Mato Grosso State, Sapezal Municipality: LIRP 8966 (1 CS, 38.3 mm SL), rio Juruena, Bacia do rio Tapajós, c. 12°51’0’’S 58°55’38’’W, 11–21 Jan 2010, Rodrigo Ilário; MZUSP 113740 (1, 28.9 mm SL) collected with holotype; LIRP 8968 (1, 38.4 mm SL), rio Juruena, Bacia do rio Tapajós, c. 12°50’59’’S 58°55’36’’W, Aug 2010, Rodrigo Ilário.

Diagnosis. Creagrutus nigrotaeniatus differs from all its congeners with exception of C. cracentis Vari & Harold , and C. maxillaris (Myers) by having 8–10 dentary teeth (vs. 4–7) and 4–5 post-anal scales (vs. 1–2). The new species is further distinguished from most congeners (except C. varii Ribeiro et al. , C. gephyrus Böhlke & Saul , C. cracentis , and C. maxillaris ) by the morphology of the dentigerous surface of the premaxilla, which is longitudinally elongate from ventral view (vs. dentigerous surface triangular) (Fig. 2). The new species is additionally distinguished from C. varii by having 8–10 branched anal-fin rays (vs. 15–17), and from C. gephyrus by having 4–5 maxillary teeth (vs. 7–11). It differs from C. cracentis and C. maxillaris by the presence of a dark mid-lateral stripe extending from the posterior margin of orbit to the distal tip of middle caudal fin rays (vs. midlateral stripe absent), anterior dentary teeth tricuspid (vs. anterior dentary teeth pentacuspid), and 4–5 maxillary teeth (vs. 8–12).

Creagrutus nigrotaeniatus presents a condition unique for the genus: the anterior margin of hyomandibula straight or slightly concave (#26:0) (Fig. 3). Further, the following seven character-states are optimized as nonexclusive autapomorphies for the species and can be useful to distinguish it from other congeners: #2(0): primary premaxillary tooth series with the gap between first and second teeth distinctly greater than the spaces between the remaining teeth in the series (Fig. 2); #3(0): anterior tooth of premaxillary tooth triad positioned, at least in part, within gap between first and second tooth in primary tooth series (Fig. 2); #9(0): primordial ligament (= preanguloparamaxillar ligament of Datovo & Vari, 2013) with a single ventral attachment to the lateral surface of the anguloarticular (Fig. 4); #16(1): medial opening of the dentary foramen located distinctly anteroventral to the tip of Meckel’s cartilage; #29(0): anterior portion of the laterosensory canal segment in first infraorbital terminating distinctly posterior to the anterior margin of this bone (Fig. 5); #45(1): presence of the third posttemporal fossa within the epioccipital; and #55(0): one epural present.

FIGURE 0 1. Creagrutus nigrotaeniatus : a. LIRP 8967 (43.1 mm SL) holotype; b. LIRP 8968 (38.4 mm SL) paratype; c. MZUSP 113740 (28.9 mm SL) recently collected paratype (photo by Rodrigo Ilário).

Description. Morphometric data of the holotype and paratypes are given in Table 1 . Greatest body depth at vertical through dorsal-fin origin. Head pointed anteriorly in lateral view. Dorsal profile of head convex from tip of snout to vertical through posterior nostril, nearly straight from that point to distal tip of supraoccipital spine; body profile slightly convex from latter point to origin of dorsal fin, straight along dorsal-fin base, somewhat straight from dorsal-fin base terminus to adipose-fin origin, and slightly concave from that point to anteriormost dorsal caudal-fin procurrent ray. Ventral profile of head and body convex from tip of lower lip to pelvic-fin insertion, slightly concave from that point to anal-fin origin, straight along anal-fin base and concave from this point to origin of anteriormost ventral caudal-fin procurrent ray. Caudal peduncle relatively elongate.

Upper jaw slightly longer than lower jaw. Premaxillary dentition in three series: irregular primary row typically with 4*(3), or 5(1) tricuspid teeth; triangular cluster composed of three large tricuspid teeth, with posterolateral tooth slightly largest; single tricuspid tooth located laterally to region of second teeth of primary premaxillary row. Maxilla with 4*(2) or 5(2) tricuspid or conical teeth; anteriormost tooth largest. Dentary teeth 8*(2), 9(1) or 10(1); all tricuspid, central cusp rounded and distinctly larger than lateral ones; teeth decreasing in size from mesialmost tooth to lateral ones. First gill arch with 4(1) hypobranchial, 7(1) ceratobranchial, and 4(1) epibranchial gill-rakers. Branchiostegal rays 4(1).

FIGURE 0 2. Right upper jaw of Creagrutus nigrotaeniatus LIRP 8966 (38.3 mm SL), right side, ventral view. Max—maxilla; pmx—premaxilla; ppt— primary premaxillary tooth series; slt— single lateral tooth; trc— triangular cluster.

Scales cycloid, circulii restricted to anterior covered area of scales, with few (around 8) divergent radii extending to posterior margin of scales. Lateral line slightly curved ventrally, with 37*(2), 38(1) or 39(1) perforated scales. Longitudinal scale rows between dorsal-fin origin and lateral line 4* (4); longitudinal scale rows between lateral line and pelvic-fin origin 3*(4). Predorsal scales 8(1) or 9*(3). Circumpeduncular scales 14*(4). Single row of 5 to 8 elongate scales at the base anal-fin rays.

Pectoral-fin rays i,12(3) or i,13*(1). Tip of pectoral fin not reaching vertical through pelvic-fin insertion. Pelvic-fin rays i,7*(4). Tip of pelvic fin not reaching vertical through anal-fin insertion. Supraneurals 4(2) or 5*(2), its dorsal portion enlarged, anterior to 5th*(4) to 8th(2) or 9th*(2) vertebral centra. Dorsal-fin rays ii,8*(4). First dorsal-fin pterygiophore inserted behind neural spine of 9th(1) or 10th*(3) vertebral centrum. Distal margin of expanded dorsal fin slightly concave. Posterior three branched dorsal-fin rays longer than middle rays. Dorsal-fin base on middle of body (SL); terminus anterior to vertical through anal-fin origin. Anal-fin rays iii,8(1), 9(2) or 10*(1). Distal margin of anal fin slightly concave. First anal-fin pterygiophore inserted posterior to haemal arch of 16th(1) or 17th*(3) vertebral centrum. Adipose fin present. Caudal fin forked, lobes approximately similar in size. Principal caudal-fin rays 10/9*(4). Dorsal procurrent caudal-fin rays 11*(2), 12(1) or 13(1), ventral procurrent caudal-fin rays 11(2) or 12*(2). Precaudal vertebrae 16*(2) or 17(2), caudal vertebrae 20*(3) or 21(1), total vertebrae 36*(1) or 37(3).

Color in alcohol. Background color yellowish. Head dark, densely pigmented in dorsal view from snout tip to supraoccipital spine. Maxilla and lower jaw with few scattered dark chromatophores. Antorbital and first to third infraorbitals covered with sparse, scattered dark cromatophores, these larger and more concentered on fourth to sixth infraorbitals, and dorsal portion of opercle. Guanine deposits on infraorbitals, opercular bones and branchiostegal membrane. Ventrolateral and ventral portions of head somewhat whitish. Midline dorsal scales darkly pigmented from posterior tip of supraoccipital to anteriormost dorsal caudal-fin procurrent ray. Midlateral scales densely pigmented, forming dark longitudinal stripe extending from posterior margin of orbit to end of median caudal-fin rays. Longitudinal stripe approximately two scale wide. Scales above longitudinal stripe with chromatophores on its distal portion. Scales below longitudinal stripe with very few scattered pigmentation. Single, vertically elongate, humeral blotch subjacent to longitudinal stripe, encompassing 2-3 scales horizontally and 3–4 scales vertically, including lateral line. Borders of humeral blotch diffuse. Dorsal fin dark pigmented on its distal half, with chromatophores concentrated on anterior and posterior borders of rays and intervening membranes. Pectoral, pelvic and anal fins with few dark chromatophores distributed along ray borders; border of unbranched rays more pigmented than others. Caudal fin mostly hyaline, except for extension of midlateral longitudinal stripe along five median caudal fin rays. Adipose fin hyaline.

FIGURE 0 3. Opercular and hiomandibular bones of Creagrutus nigrotaeniatus LIRP 8966 (38.3 mm SL), right side, medial view. Fpa—foramen for the afferent pseudobranchial artery; hym—hyomandibula; iop—interopercle; mqf—metapterygoid-quadrate fenestra; mtp—metapterygoid; ope—opercle; pop—preopercle; qua—quadrate; sbo—subopercle; sym—sympletic.

Color in life. Life coloration (Fig. 1c) similar to described above, except for: body and head pale yellow, lighter ventrally; proximal half of dorsal fin and distal two-thirds of adipose fin somewhat reddish; distal half of dorsal fin dark pigmented. Pectoral fin pale yellow on its base, hyaline on its distal portion. Anal fin with dark scattered pigmentation. Lower caudal-fin lobe red pigmented on its base. Eyes reddish dorsally.

Etymology. The specific name nigrotaeniatus , derives from the Greek nigro black and taenia meaning ribbon, referring to the black lateral longitudinal stripe on the body.

Sexual dimorphism. Pelvic-fin hooks were observed in a single specimen (LIRP 8968). Hooks were present at the medial margin of the middle portion of the second branched pelvic-fin ray.

Distribution. Creagrutus nigrotaeniatus is only known from its type locality in the upper rio Juruena (Fig. 6).

Tables

TABLE 1. Morphometric data for Creagrutus nigrotaeniatus.

	n mean range	SD	Holotype
Standard Length (mm)	4 37.2 28.9 – 43.1		43.1
Percents of SL
Depth at dorsal-fin origin	4 21.7 20.0 – 23.5	1.6	23.5
Snout to dorsal-fin origin	4 49.0 47.1 – 50.8	1.5	49.5
Snout to pectoral-fin origin	4 26.2 24.7 – 28.1	1.5	28.1
Snout to pelvic-fin origin	4 48.0 45.2 – 49.4	1.9	49.4
Snout to anal-fin origin	4 65.8 62.7 – 67.6	2.3	67.6
Caudal peduncle depth	4 10.3 10.0 – 10.9	0.4	10.0
Caudal peduncle length	4 21.2 20.4 – 22.1	0.7	20.4
Pectoral-fin length	4 18.8 18.1 – 19.1	0.5	18.9
Pelvic-fin length	4 15.2 14.2 – 16.2	0.9	15.8
Pelvic-fin insertion to anal-fin origin	4 18.1 17.9 – 18.5	0.3	17.9
Dorsal-fin origin to anal-fin origin	4 27.8 26.3 – 29.3	1.3	29.3
Dorsal-fin origin to pelvic-fin insertion	4 21.4 20.0 – 23.1	1.5	23.1
Dorsal-fin origin to pectoral-fin insertion	4 28.9 28.4 – 29.5	0.5	29.5
Dorsal-fin base length	4 12.4 11.9 – 12.8	0.4	12.5
Dorsal-fin length	4 19.6 18.3 – 20.6	1.1	20.6
Anal-fin base length	4 13.3 12.4 – 14.4	0.9	14.4
Anal-fin lobe length	4 16.6 15.7 – 18.1	1.0	16.4
Eye to dorsal-fin origin	4 33.6 32.8 – 34.8	0.9	33.9
Dorsal-fin origin to caudal-fin base	4 53.9 53.0 – 56.1	1.5	53.3
Bony head length	4 25.9 25.0 – 26.5	0.6	26.5
Percents of head length
Horizontal eye diameter	4 31.0 29.4 – 31.8	1.1	29.4
Postorbital head length	4 36.66 35.5 – 38.8	1.4	36.0
Snout length	4 29.7 29.3 – 30.7	0.7	30.7
Least interorbital distance	4 29.6 28.0 – 32.5	2.0	28.9
Upper jaw length	4 29.7 28.1 – 30.9	1.2	30.1