Creagrutus mucipu Vari & Harold 2001

Creagrutus mucipu

DIAGNOSIS.—The pattern of very dark, posteriorly directed, chevron-shaped pigmentation patches along the midlateral surface of the body is autapomorphic for Creagrutus mucipu among the species of Creagrutus and Piabina. Creagrutus mucipu also has the distal margin of the caudal fin outlined with a band of dusky pigmentation. This dark distal caudal-fin pigmentation is separated from more basal dusky pigmentation by a hyaline region, a pigmentation pattern not found elsewhere in Creagrutus and Piabina. In addition to these autapomorphic pigmentation features, the combination of the possession of premaxillary dentition arranged in the three components generalized for most of the species of Creagrutus and Piabina without a pronounced gap between the first and second teeth of the primary series, 5 teeth in the primary series of each premaxilla, 3 maxillary teeth, 7 teeth on each dentary, 9 or 10 predorsal median scales, 2 post-anal median scales to the anal-fin origin, 36 to 39 lateral line scales without a lamellar process over each pore, 4 scale rows between the dorsal-fin origin and the lateral line, 11 branched anal-fin rays, 6 or 7 gill rakers on the upper limb and 9 to 11 gill rakers on the lower limb of the first arch, the distance from the snout to the dorsal-fin origin (45.0%–47.9% of SL), the distance from the dorsal-fin origin to the anal-fin insertion (32.4%–36.5% of SL), the caudal peduncle depth (12.5%–13.3% of SL), the head length (24.9%–27.5% of SL), the snout length (24.5%–29.0% of HL), the postorbital head length (40.6%–44.8% of HL), the interorbital width (29.7%–33.0% of HL), the well-developed third infraorbital whose straight ventral margin contacts the horizontal limb of the preopercle, the lack of a distinct spot of dark pigmentation at the base of the middle caudal-fin rays, the faint, vertically elongate, ventrally attenuating humeral mark with straight anterior and posterior margins and lacking a secondary, dorsal patch of pigmentation, the absence of a distinct patch of pigmentation on the dorsal fin, and the lack of a series of dark, round spots along the midlateral surface of the body distinguishes Creagrutus mucipu within the clade formed by Creagrutus and Piabina.

DESCRIPTION.—Morphometric and meristic data for Creagrutus mucipu in Table 38. Head and body moderately robust; body more robust in larger individuals. Greatest body depth proportionally greater in larger individuals; at, or slightly anterior to, vertical through dorsal-fin origin in smaller examined paratypes; at dorsal-fin origin in larger examined individuals. Dorsal profile of head convex from margin of upper lip to slightly posterior of vertical through posterior nostril, then nearly straight to tip of supraoccipital spine. Interorbital region transversely convex. Predorsal profile of body slightly convex, with moderate change in alignment relative to profile of posterior portion of head. Predorsal region of body with obtuse median ridge along posterior half of its length in larger specimens. Prepelvic profile of lower jaw with obtuse angle at anteroventral corner of dentary. Ventral profile of head posterior to obtuse angle on dentary slightly convex to isthmus. Ventral profile of body slightly convex overall and continuing profile of ventral profile of head. Prepelvic region of body obtusely flattened transversely.

Characters A B

Morphometrics

Standard length 50.1 37.6–56.1

1. Snout to anal-fin origin 65.3 62.0–66.0

2. Snout to pelvic-fin insertion 47.5 46.2–48.9

3. Snout to pectoral-fin insertion 26.7 24.3–26.4

4. Snout to dorsal-fin origin 46.1 45.0–47.9

5. Dorsal-fin origin to hypural joint 59.1 57.6–59.6

6. Dorsal-fin origin to anal-fin origin 35.7 32.4–36.5

7. Dorsal-fin origin to pelvic-fin insertion 30.1 28.5–32.6

8. Dorsal-fin origin to pectoral-fin insertion 34.1 32.1–36.2

9. Caudal peduncle depth 12.8 12.5–13.3

10. Pectoral-fin length 20.4 19.2–22.3

11. Pelvic-fin length 17.2 16.0–18.5

12. Dorsal-fin length 21.8 21.5–23.4

13. Anal-fin length 19.6 18.0–20.4

14. Head length 27.5 24.9–27.2

15. Postorbital head length 41.9 40.6–44.8

16. Snout length 24.5 24.6–29.0

17. Bony orbital diameter 32.2 32.4–36.4

18. Interorbital width 29.7 29.9–33.0

Meristics

Lateral line scales 39 36–39

Scale rows between dorsal-fin origin and lateral line 4 4

Scale rows between anal-fin origin and lateral line 3 3

Predorsal median scales 9 9–10

Branched dorsal-fin rays 8 8

Branched anal-fin rays 11 11

Branched pelvic-fin rays 7 5–71

Pectoral-fin rays 13 12–14

Vertebrae 36 35–36

1Five branched anal-fin rays present on only on one pelvic fin of 1 of 8 paratypes; 7 branched anal-fin rays limited to larger specimens.

Head obtusely rounded in lateral view, but more compressed transversely in dorsal view. Upper jaw slightly longer than, and overhanging, lower jaw. Snout fleshy anteriorly, with scattered papillae on anterior surface, papillae field continuing onto fleshy folds between premaxillary teeth. Lower lip fleshy anteriorly, with scattered papillae on upper and anterior portions.

Infraorbital series well developed. Ventral margin of third infraorbital straight and contacting horizontal limb of preopercle in specimens of all available sizes. Posterior margins of third through fifth infraorbitals approaching, but not contacting, vertical limb of preopercle; gap narrow in specimens of all available sizes.

Premaxillary dentition in three series: primary row arched, with 5 teeth, without pronounced gap between first and second tooth of series; triangular cluster of 3 larger teeth, without pronounced gap between first and second tooth of series but with medial teeth of contralateral clusters nearly in contact; and single tooth of form similar to that of primary series occurring lateral to third tooth of primary tooth row. Maxilla with 3 tricuspidate teeth. Dentary with 5 or 6 tricuspidate teeth. Second dentary tooth somewhat larger than first tooth and distinctly larger and about approximately one and one-half times vertical extent of third tooth; fourth tooth distinctly smaller than third tooth; fourth through last teeth in series progressively gradually decreasing in size.

Dorsal-fin rays ii,8 in all specimens. Distal margin of dorsal fin slightly concave. Anal-fin rays ii, 11 in all specimens. Distal margin of anal fin concave. Anal-fin hooks present on first, first and second, or first through third rays of mature males. Pectoral-fin rays i, 11–13. Tip of pectoral fin reaching posteriorly nearly to pelvic-fin insertion. Pelvic-fin rays i,5–7; 5 branched rays limited to pelvic fin on one side of one specimen; 7 branched rays occurring only in larger examined specimens. Tip of pelvic fin reaching posteriorly nearly to anal-fin origin. Pelvic-fin hooks present on 5 or 6 branched rays in mature males; medial branched ray lacking hooks when only 5 hook-bearing rays present.

Gill rakers 6–7 + 9–11.

COLORATION IN ALCOHOL.—Ground coloration of specimen very light tan to tan. Dorsal surface of head in smaller individuals with dense field of dark chromatophores on membranes overlying brain and with field of scattered, smaller, dark chromatophores on surface of head; chromatophore concentration distinctly less pronounced anteriorly. Surface chromatophore field gradually becoming more concentrated in larger specimens and forming field of dense pigmentation in larger specimens, albeit somewhat less concentrated on dorsal surface of snout. Region anterior to nostrils with only slightly more concentrated field of dark chromatophores in specimens of all sizes; these not forming distinct crescent-shaped patch in that region such as found in many congeners. Area anteroventral to orbit with diffuse field of small, dark chromatophores extending from ventral margin of nares to ventral margin of orbit. Dorsal portion of opercle and lateral surface of fourth though sixth infraorbitals with scattered, stellate, dark chromatophores in smaller individuals; chromatophore field extending somewhat more ventrally and to a degree under orbit in larger specimens.

Scales on dorsal portion of body with exposed margins outlined by small, dark chromatophores, giving region overall dark, reticulate, pigmentation pattern. Midlateral region of body with series of dark, chevron-shaped marks formed by deep-lying chromatophores. Individual chevron-shaped marks with arms relatively straight, sometimes with secondary branches extending at angles from main body of mark. Chevron pattern most obvious in region ventral of dorsal fin, becoming less apparent on body posteriorly. Dorsal portions of chevrons more obvious than ventral portions in many individuals, particularly smaller specimens. Ventral portion more apparent in most larger individuals. Humeral mark formed of relatively faint to distinct, small, dark chromatophores. Overall form of humeral mark vertically elongate and ventrally attenuating, with anterior and posterior margins somewhat variable, ranging from relatively straight to having concave anterodorsal and posterodorsal margins, or convex anterodorsal margin. Humeral mark extending dorsally to one scale from middorsal line and ventrally to level approximately one scale dorsal of horizontal through dorsal limit of pectoral-fin insertion. Faint midlateral body stripe formed by small, dispersed, dark chromatophores extending from about 2 scales posterior of humeral mark posteriorly to rear of caudal peduncle. Stripe widest and overlying dark chevron-like marks anteriorly, gradually narrowing and only partially overlapping dark midlateral marks along posterior portion of body. Stripe merging into field of scattered, dark chromatophores on caudal peduncle.

Dorsal fin with small dark chromatophores on membranes and outlining many fin rays. Anal fin with scattered, dark chromatophores on distal two-thirds of membranes of branched rays. Pectoral fin with small chromatophores on membranes. Pelvic fin hyaline. Caudal fin with basal dusky pigmentation extending out along rays of each lobe. Distal margin of caudal fin outlined by band of diffuse dark pigmentation. Distal and basal regions of caudal pigmentation separated by hyaline region.

ETYMOLOGY.—The species name, mucipu, is an acronym derived from Museu de Ciências e Tecnologia, PUCRS (Pontificia Universidade Católica do Rio Grande do Sul) whose staff collected the holotype of the species and brought it to our attention, and who have provided valuable assistance to the authors in this and other projects. It is treated as a noun in apposition.

ECOLOGY.—The holotype and paratypes, the only know specimens of Creagrutus mucipu, were collected in residual ponds in the bed of the Rio Tocantins following the interruption of water flow through the channel as a result of the closure of a dam, the Repressa da Usina Hidroelectica de Serra da Mesa. The natural habitat of C. mucipu is, thus, unknown, but the river had clear water and a bottom of small stones and rocks prior to the dam closure (C. Lucena, pers. comm., 2000). The paratype series of C. mucipu was collected together with specimens of C. menezesi and C. figueiredoi. A female that was prepared for clearing and staining in this study (USNM 350449, 41.4 mm SL) had numerous well-developed eggs. It was collected in the late October to early November period of 1996.

SEXUAL DIMORPHISM.—The relatively small available sample of Creagrutus mucipu shows a definite difference in the relative size of the two sexes. Mature males, as indicated by the presence of body hooks on the anterior rays of the anal fin and on the branched rays of the pelvic fin range from 37.6 to 44.9 mm SL (n=3). Females lacking those modifications range from 40.8 to 56.1 mm SL (n=6).

DISTRIBUTION.—Creagrutus mucipu is known only from the type locality in the upper portions of the Rio Tocantins basin (Figure 67, diamond).

MATERIAL EXAMINED.—9 specimens (9, 37.6–56.1).

HOLOTYPE.—BRAZIL. Goiás: Município de Minaçu, Rio Tocantins, at port of Rubao (13°44′31″S, 48°08′29″W), collected by C.A.S. Lucena and J.J.P. Silva, 7 Nov 1996; MCP 19511, 1 (50.1).

PARATYPES.—8 specimens(8, 37.6–56.1).

BRAZIL. Goiás: Município de Minaçu/Colinas do Sul. Rio Tocantins, in large pools below dam of Usina Hidroelectica de Serra da Mesa following closure of dam to fill reservoir (approximately 13°44′S, 48°08′W), collected by D.F. Moraes et al., 28 Oct to 3 Nov 1996, MNRJ 17337, 6 (37.6–56.1); USNM 350449, 2(41.4–51.7).

Creagrutus mucipu és una espècie de peix de la família dels caràcids i de l'ordre dels caraciformes.

Creagrutus mucipu es una especie de peces de la familia Characidae en el orden de los Characiformes.

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Creagrutus mucipu Creagrutus generoko animalia da. Arrainen barruko Actinopterygii klasean sailkatzen da, Characidae familian.

黏鈎齒脂鯉，為輻鰭魚綱脂鯉目脂鯉亞目脂鯉科的其中一個種，分布於南美洲托坎廷斯河上游流域，體長可達5.6公分，棲息在底中層水域，生活習性不明。