Hypostomus cochliodon Kner 1853

Jonathan W. Armbruster, 2003, The species of the Hypostomus cochliodon group (Siluriformes: Loricariidae)., Zootaxa 249, pp. 1-60 : 21-25

Hypostomus cochliodon Kner 1853

(Fig. 7)

Hypostomus cochliodon Kner 1853 : 265-267, pl. 2 fig. 1.

Hypostomus hypostomus Heckel, in Kner 1853 : 265 (name published in synonymy of Hypostomus cochliodon ).

Loricaria melanoptera Natterer, in Kner 1853 : 265 (name published in synonymy of Hypostomus cochliodon )

Material examined: UNKNOWN LOCALITY . AMNH 97884 , 2, (80.9-155.5) . BRAZIL. Mato Grosso: Rio Cujaba, NMW 46277, 1 (152.9, lectotype) and NMW 44101 (179.3, paralectotype) . Near Cuiabá, AMNH 97880, 9, 1 cs, (68.9-124.2) . Arroio, Rio do Bugre - Rio Jauru - Rio Paraguai dr. at km 165 on Estrada Porto Esperidião /Pontes e Lacerda (BR 174), ca 48 km de Esperidião, USNM 326357, 4, 1 cs, (75.8-143.6) . Arroio Cruzando, Rio Paraguai dr. on estrada Tangara da serra 1, Barra do Bugres, near nova Olimpia, USNM 326319, 2, 1 cs, (70.5-96.6) . PARAGUAY. Alto Paraguay: Arroyo Ytyguazu, Río Paraguay dr. Primavera, Caacupe, ANSP 124105, 1, (111.4) . Río Apa, Río Paraguay dr. ca 0.5 km upstream (=east) of bridge between Brazil and Paraguay in Bella Vista, 22°06’30”S, 56°30’W, UMMZ 206797, 6, (122.6-211.38) . Amambay: Río Aquidaban, Río Paraguay dr. at Paso Horqueta, ca 24 km NNW of Loreto, 23°03’48”S, 57°23’W, UMMZ 207821, 1, (151.4) . Río Aquidaban, Río Paraguay dr. in Parque Nacional Cerro Cora ca 32 km WSW of Pedro Juan Caballero, 22°38’12”S, 56°03’W, UMMZ 206767, 1, (130.0) . Río Aquidaban, Río Paraguay dr. Parque Nacional Cerro Cora, USNM 232310, 1, (131.1) , USNM 232312, 2, (119.4-164.4) , and USNM 232311, 1, (146.7) . Canendiyu: Río Jejui, Rio JejuiGuazu - Río Paraguay dr. ca. 41 km N Curuquaty and 2 km S Ygantini, 24°08’12”S, 55°37’W, UMMZ 206338, 3, 3 cs, (142.2-168) . Concepcíon: Río Ypané, Río Paraguay dr. at ferry crossing, ca 2.0 km S by dirt road to Belen (which is ca 18 km ESE Concepcion), 23°29’30”S, 57°15’W, UMMZ 207988, 5, 2 cs, (80.3-113.1) and UMMZ 207989, 3, (66.1-76.3) . Cordillera: Río La Plata dr. 1.6 km by road S of Tobati, UMMZ 203865, 1, (140.8) . Arroyo Tobati, Río Paraguay dr. small river ca. 0.3 km E of dirt road, 1.6 km S of Tobati, 25°18’30”S, 57°04’W, UMMZ 205771, 1, (151.6) and UMMZ 205770, 1, (148.0) . Arroyo Tobati, Río Piribebuy - Río Paraguay dr. ca 0.1 km east of Tobati, 25°16’14”S, 57°03’W, UMMZ 205809, 1, (106.5) . Arroyo Yaguary-Guazú, Río Aquidaban dr. at bridge on dirt highway (Route #5) ca 26.1 km NE of junction with Route#, ca 68 km WSW of Pedro Juan Caballero, 27°47’24”S, 56°21’W, UMMZ 206691, 1, 147.0) . Paraguari: Río Tebicuary dr. Salto de Pirareta, ca. 400 m below falls, 5.8 km S. of Piribebuy and 10 km W on dirt road, UMMZ 205673, 3, (112.4-170.5) . San Pedro: Río Ypané, Río Paraguay dr. on S bank at bridge on dirt highway, 52.7 km S of jct. with highway #5 at Yby-Yau, 23°27’18”S, 56°31’W, UMMZ 208023, 1, (164.0) and UMMZ 208024, 2, (94.9-120.1) . Villa Hays: no exact locality, FMNH 59735, 1, (151.7) .

Diagnosis: Hypostomus cochliodon can be distinguished from all other members of the H. cochliodon group by its almost entirely brown coloration with ventral half of dorsal plate row and dorsal half of supramedian plate row slightly lighter than lower rows forming a tan stripe, and spots, when present, small and widely placed (vs. spots usually welldeveloped and closely placed). Unlike most other members of the H. cochliodon group, H. cochliodon can also be entirely dark brown with no spots anywhere on the body (other members of the H. cochliodon group may be very dark, but will retain spots on fins or the abdomen).

Description: See Hypostomus cochliodon group description for more details. Morphometric data given in Table 1. Color normally almost entirely dark brown with wide, tan stripes dorsally and ventrally. Tan dorsal stripe on ventral half of dorsal plate row and dorsal half of supramedian plate row; stripe sometimes crossed by dark saddles or with dark spots anteriorly. Tan ventral stripe on ventral half of inframedian plate row and entire ventral plate row. Dorsal stripe forks on nape with one branch continuing straight to eye and other branch ending at posterior tip of supraoccipital. Tan wedge occasionally present at base of supraoccipital crest. Dorsal surface of snout light or mottled. Spots on body often absent, but sometimes present on any part of the body, well separated from one another. Abdomen colored as sides, but usually slightly lighter. Color entirely dark brown without spots in some individuals.

Dorsal fin usually short, not reaching preadipose plate when depressed in most specimens. Depressed pectoral-fin spine ventral to pelvic fin reaches beyond bases of pelvic-fin rays. Tip of pectoral-fin spine of nuptial males with stout, recurved, hypertrophied odontodes.

Keels moderate to well-developed; keel odontodes occasionally sharp. Orbits forming ridge distinctly raised above medial surface of head; ridges of dorsal and lateral aspect of head well-developed. Longitudinal ridge on pterotic-supracleithrum beginning at posterodorsal corner of eye formed from raised bone and slightly larger odontodes present. Opercle usually supporting much more than 10 odontodes; in some specimens the opercle does not support odontodes (see Comments). Nuptial body odontodes present (Fig. 2B). Plates in skin anterior to dorsal-fin spines few or absent (Fig. 6A; Table 7).

Each jaw with 6-27 teeth (mode = 12). Size of teeth variable (see Comments). Average angle between dentaries 68° (SD = 14°; range: 42°-99°; N=30). Lateral line plates 26-30; dorsal plates 7-8; interdorsal plates 5-7; adipose caudal plates 9-11.

Range: The upper 2/3 of the Río Paraguay basin of Brazil and Paraguay (Fig. 8). Hypostomus cochliodon is allopatric to all other species of the H. cochliodon group.

Comments: The smallest juveniles often have teeth very similar to algivorous-detritivorous species of Hypostomus . As Hypostomus cochliodon grow, the teeth apparently are replaced by successively larger, more spoon-shaped teeth, and tooth number decreases. Hypostomus cochliodon is variable in color pattern, size of keels, and number of odontodes on the opercle (0 to 30). The variation in number of odontodes may indicate that H. cochliodon as presently delimited may represent more than one species; however, the variation in opercular odontode number does not appear to be correlated with variation in other characteristics.