Curimatopsis crypticus Vari 1982

Curimatopsis crypticus

Curimatopsis macrolepis.—Eigenmann, 1912:260 [British Guiana (Guyana), Maduni Creek, Lama Stop-Off, Rockstone, ?Cave Grove Corner, ?Botanic Gardens, ?Konawaruk, ?Gluck Island, ?Wismar].—Myers, 1929:618 [in part, Guyana; ?Brazil, Santarem, sexual dimorphism].—Boeseman, 1952:183 [Surinam].—Hoedeman, 1974:609, pl. II: fig. 122 [Surinam, breeding].

DIAGNOSIS.—A relatively stout-bodied Curimatopsis species reaching 46 mm SL. This species is distinguishable from its nearest relative, C. evelynae, in having a crescent-shaped posterior nostril separated from the anterior opening by less than the diameter of the latter aperture. In C. evelynae the posterior nostril is a round or slightly transversely elongate opening separated from the anterior nostril by a distance equal to or usually greater than the diameter of the anterior opening. The caudal peduncle spot in C. crypticus is more intense than in its sister species and centered in the midlateral plane of the caudal peduncle. In C. evelynae the fainter caudal peduncle markings are centered ventral to the midlateral plane of the peduncle or may be lacking totally. Males of C. crypticus have the peduncle spot continued onto middle caudal rays as a distinct stripe. Curimatopsis evelynae males, in contrast, have only scattered chromatophores on the middle caudal rays. Larger specimens of these species can also be distinguished by the relatively deeper body of C. crypticus (see Figure 17). Curimatopsis crypticus is readily distinguished from C. microlepis by its lower number of longitudinal body scales (27 to 30 in contrast to 57 to 63). Various researchers have previously misidentified Curimatopsis crypticus as C. macrolepis (see “Remarks”). These species are readily distinguished by the relatively shorter postorbital portion of the head in C. crypticus (0.40–0.44 of HL) than in C. macrolepis (0.45–0.53 of HL) and the lack in C. crypticus of the overlap of the anterior portion of the upper lip by the lengthened lower jaw that is characteristic of C. macrolepis, along with numerous osteological characters (see “Phylogenetic Analysis”).

DESCRIPTION.—Body moderately elongate and compressed. Dorsal profile of head straight or slightly convex. Dorsal profile of body nearly straight to origin of rayed dorsal fin, gently convex from that point to base of ultimate dorsal ray and nearly straight from rear of fin to dorsal portion of caudal peduncle. Dorsal surface of body anterior to rayed dorsal fin somewhat flattened but without definite longitudinal ridges. Dorsal body surface posterior to rayed dorsal fin transversely curved. Ventral profile of body smoothly convex, convexity more pronounced in females. Ventral region of body anterior to pelvic fin insertion somewhat flattened but without definite longitudinal keels laterally. Ventral surface of body posterior to insertion of pelvic fin transversely rounded. Greatest body depth at origin of rayed dorsal fin 0.31–0.35 [0.35]; snout tip to origin of rayed dorsal fin 0.47–0.55 [0.55], (0.47–0.53 in females, 0.51–0.55 in males); snout tip to origin of anal fin 0.74–0.78 [0.74]; snout tip to insertion of pelvic fin 0.55–0.61 [0.55]; snout tip to anus 0.78–0.83 [0.80]; origin of rayed dorsal fin to hypural joint 0.52–0.56 [0.53]. Rayed dorsal fin pointed, anterior rays about twice length of ultimate elements. Pectoral fin pointed, pectoral fin length 0.16–0.23 [0.22], reaching two-thirds distance to insertion of pelvic fin. Pelvic fins pointed, pelvic fin length 0.18–0.24 [0.22], reaching or falling slightly short of origin of anal fin. Caudal peduncle depth sexually dimorphic, peduncle depth 0.12–0.15 in females, 0.16–0.18 [0.18] in males. Caudal fin scaled only at base. Caudal fin form sexually dimorphic, bifid in females; middle rays of caudal fin lengthened in males, fin trifid with upper lobe longest.

Head pointed, head length 0.30–0.35 [0.33]; lower jaw as long as upper, not overlapping the tip of upper lip; snout rounded, snout length 0.22–0.27 [0.22]; nostrils separated by a distance less than diameter of anterior nostril, anterior nostril rounded, posterior nostril crescent-shaped or distinctly transversely elongate; orbital diameter 0.31–0.36 [0.35]; postorbital portion of head 0.40–0.44 [0.43]; gape width 0.22–0.24 [0.23]; interorbital width 0.37–0.40 [0.40].

Twenty-seven to 30 [29] scales in a longitudinal series from supracleithrum to hypural joint; 3 to 5 pored lateral line scales, lateral line canals straight; 2 or 3 series of scales extending beyond hypural joint onto base of caudal fin; 11 to 13 [11] scales in a transverse series extending posteriorly from the origin of rayed dorsal fin.

Rayed dorsal fin rays ii,8,i or ii,9 [ii,9]; anal fin rays ii,7–8 [ii,8]; pectoral fin rays 12 to 14 [13]; pelvic fin rays i,7,i.

Total vertebrae 28(4), 29(36), 30(1) [29].

Color in Alcohol: Alcohol-fixed specimens with overall coloration silvery. Formalin-fixed specimens lacking guanine. Head darker dorsally with scattered chromatophores on opercle. Body darker dorsally with scales outlined by series of small chromatophores. Pigmentation less pronounced ventral to lateral midline of body. A progressively widening lateral body stripe running from behind supracleithrum to midlateral surface of caudal peduncle. Stripe more intense and extending farther anterior in larger specimens. Stripe continuous with a round or slightly horizontally oblong spot on rear of caudal peduncle. Spot terminating at base of middle caudal rays in females, continuous with stripe on middle caudal fin rays in males. Median fins with chromatophores outlining fin rays. Paired fins hyaline or with scattered chromatophores.

DISTRIBUTION.—Atlantic slopes of the Guianas, Rio Branco, and lower portions of the Amazon River and Rio Negro (see Figure 18).

ETYMOLOGY.—From the Greek for hidden or secret, referring to this species having been “hidden from science” as a consequence of the long-term confusion that has existed between it and Curimatopsis macrolepis.

MATERIAL EXAMINED.—Holotype: GUYANA: Rupununi District, stream 2 km east of Lake Amucu (∼ 3°43′N, 59°25′W), USNM 226872 (27.7), male.

Paratypes: Sixty-five specimens. BRAZIL: Igarape Anapichi leading to Rio Negro 64 miles northwest of intersection of Rio Negro and Rio Branco, Sep 1975, H. Axelrod, USNM 226880, 15 (21.2–37.2); ANSP 146864, 1 (24.3); AMNH 45096, 1 (31.6); MZUSP 15974–75, 2 (25.2–29.0); BMNH 1981.4.27:1, 1 (27.8). Para, Monte Alegre, C. Ternetz, USNM 228354, 3 (43.8–45.4); BMNH 1926.10.27:208–227, 22 (21.0–43.1). Para, Belem, Lagoa da Providencia, N. Menezes, Jul 1965, MCZ 46201, 1 (23.8). Para, Santarem, Uruara Brook into Rio Tapajos, USNM 226883, 4 (33.4–36.3); MZUSP 15976–77, 2 (32.9–33.5). Middle Rio Negro, Praya Mofulu on Rio Itu, M. Brittan, Apr 1964, USNM 226884, 3 (30.6–34.2). Brazilian-Bolivian border region near Guajara-Mirim, 1970, von Graeve, USNM 226885, 1. GUYANA: Maduni, C. Eigenmann, MCZ 30048, 2 (28.5–36.6). Lama Stop-Off, C. Eigenmann, AMNH 45094, 2 (37.3–38.1). Rockstone, C. Eigenmann, AMNH 45095, 2 (26.0–27.6) (see Eigenmann, 1912, pl. 83, for map of his collecting localities). Manari River, C. Hopkins, MCZ 57638, 1 (27.9).

The following nonparatype material of Curimatopsis crypticus was examined but not used as a basis for the meristics and morphometrics of the above description. GUYANA: Rupununi River, NMW 67112, 1. SURINAM: Republik, GC, 2. FRENCH GUIANA: Orapu River, Criqeue Gabrielle, GC, 23. BRAZIL: Rio Caures off Rio Negro, GC, 2.