Hypostomus plecostomoides Eigenmann 1922

Jonathan W. Armbruster, 2003, The species of the Hypostomus cochliodon group (Siluriformes: Loricariidae)., Zootaxa 249, pp. 1-60 : 42-45

Hypostomus plecostomoides Eigenmann 1922

(Fig. 19)

Hypostomus plecostomoides Eigenmann 1922 : 225-226. Holotype is lost.

Material examined: COLOMBIA. Meta: Caño Rico, Río Meta dr. at Brasilia, ca. 03°59’N, 73°08’W, ANSP 133235, 2, 1 cs, (83.6-98.8) . Quebrada Venturosa, Río Meta dr. between La Balsa and Puerto Lopez, ca. 04°05’N, 72°58’W, ANSP 133365, 1, (94.4) . Río Negrito, Río Meta dr. downstream of bridge at La Balsa, ca. 04°04’N, 73°04’W, ANSP 131658, 1, (101.7) . VENEZUELA. Anzoategui Atapirire, Río Orinoco dr. Atapirire road, Manasma, MBUCV V-16944, 1, (97.2) . Río Moquete, Río Orinoco dr. Paso bajito, MBUCV V-16922, 1, (167.0) . Río Tigre, Caño Manamo dr. near El Tigre, 08°55’38”N, 64°11’11”W, INHS 31412, 2, (69.4-105.8) . Apure: caño, Río Apure dr. 07°16’26”N, 71°05’20”W, INHS 28385, 2, (113.1-113.2) . Caño Las Mercedes, Río Apure dr. dique via Apurito, cerca San Fernando de Apure-Biruaca, 07°51’30”N, 67°22’30”W, MCNG 13923, 1, (173.4) . Caño Maporal, Río Apure dr. at the metal bridge near the Module (a field station of UNELLEZ), 07°25’30”N, 69°35’40”W, MCNG 9134, 1, (222.7) . Río Apure, Río Orinoco dr. side channel along dike opposite municipal slaughter house, 07°35’N, 67°29’W, USNM 258264, 2, (136.1-193.8) . Río Aruaca, Río Apure dr. in floodplain, paso Aruaca, 07°26’55”N, 68°26’00”W, MCNG 20655, 1, (142.8) . Aragua: Río Bue, Lago Valencia dr. Maracay, CAS 12694, 1, (218.8) . Barinas: Caño Arenosa, Río La Yuca - Río Masparro dr. 14 km N Barinas, 08°46’14”N, 70°15’30”W, INHS 31837, 3, 1 cs, (105.6- 119.4) . Caño Capa, Río Masparro - Río Apure dr. 2 mi E El Tombor, 08°21’35”N, 69°46’07”W, INHS 35487 . Caño Guanaparo, Río Apure dr. N of Apurito, 08°07’40”N, 68°20’40”W, MCNG 13025, 1, (183.2) . Caño Hondo, Río Apure dr. Agua Negra, INHS 30000, 3, 1 cs, (112.7-218.4) . Río Chiri Chiri, Río Apure dr. 0.5 km above mouth, 07°39’40”N, 71°29’01”W, MCNG 10572, 1, (169.5) . Río Mitado-seco, Río Apure dr. USNM 194210, 1, (205.4) . Río Santa Barbara, Río Apure dr. at bridge on Barinas to San Cristobal road, km 504, 07°50’10”N, 71°11’00”W, MCNG 11720, 1, (153.8) . Río Santo Domingo, Río Apure dr. in Torunos, Hacienda La Isla, 08°30’32”N, 70°05’03”W, INHS 28710, 1, (87.1) . Tributary of Río Suripa - Río Apure dr. 36 km NE La Pedrera on route 5, INHS 28284, 1, (106.4) . Tributary of Río Caipe, Río Apure dr. 6 km NE Torunos, INHS 28744, 2 cs . Bolivar: Caño Brande, Río Orinoco dr. Ciudad Bolivar, 08°14’50”N, 63°15’55”W, ANSP 166889, 1, (211.9) . Caño Caiman, Río Orinoco dr. at crossing of Caicara to Puerto Ayacucho highway 191, 2 km W of Ciudad Bolivar to Caicara highway, ANSP 162345, 1, (211.1) and MBUCV V-16855, 1, (192.0) . Caño Garrapáta, Río Orinoco dr. at bridge between Río Paguaza and Villacoa, 06°19’20”N, 67°07’00”W, MCNG 11176, 1, (125.4) . Caño Tabara, Río Nichare - Río Orinoco dr. 3 km above mouth with Río Nichare, 06°22’N, 64°58’W, MCNG 22931, 1, (188.6) . Isolated lagoon, Río Orinoco dr. 200 yards N of Jubillal, 06°57’N, 64°50’W, ANSP 141559, 1, (131.5) . Salto Icutu, Río Orinoco dr. Cedeno district, in front of camp, 05°53’N, 64°51’W, MCNG 21160, 1, (199.8) . Cojedes: Río Camoruco, Río Cojedes - Río Portuguesa dr. about 10 km NW Libertad, INHS 29061, 1, (110.1) . Río Tinaco, Río Portuguesa dr. El Baul, INHS 59831, 1, (116.4) . Guarico: Río Guarico, Río Orinoco dr. at Flores Morada’s ranch, ca. 3-4 km E of road from Calabozo to San Fernando, USNM 260217, 1, (109.6) . Río Guariquito, Río Orinoco dr. in front of Medana de Gomez, MCNG 32975, 1, (188.8) . Río San Bartolo, Río Orinoco dr. Parque Nacional Aguaro-Guariquito, Aguas Muertes, 08°04’40”N, 66°40’00”W, MCNG 15027, 1, (140.5) . Río San Bartolo, Río Orinoco dr. Parque Nacional Aguaro-Guariquito, Aguas Muertes, 08°06’30”N, 66°40’19”W, INHS 34862, 2, (175.7- 187.1) and MCNG 31701, 2, (149.0-248.5) . Río San Bartolo, Río Orinoco dr. Parque Nacional Aguaro-Guariquito, Aguas Muertes in the Payares, 08°08’01”N, 66°40’53”W, MCNG 31792, 1, (230.9) . Río San Jose, Río Guariquito - Río Orinoco dr. Parque Nacional Aguaro-Guariquito, 08°28’55”N, 66°53’19”W, INHS 34614, 1, (107.1) . Miranda: Río Cuira, Río Tuy dr. FMNH 84616, 1, (69.7) and MBUCV V-3756, 1, (140.1) . Río Tuy, Caribbean Sea dr. in pool isolated from main stream near Ocumaro de Tuy, MBUCV V-3701, 10, (96.4-103.2) . Monagas: Río Amana, Río Guanipa dr. 7 km NNW Santa Barbara, INHS 31263, 1, 2 cs, (139.7) and MCNG 29159, 1, (124.4) . Río Amana, Río Guanipa dr. Las Cañitas near El Tefero, MBUCV V-6755, 1, (107.2) . Río de Oro, Río Guarapiche - Río San Juan dr. 4 km SW Jusepin, INHS 31448, 1 cs. Río Guanipa, Caribbean Sea dr. Highway5 bridge, 09°22’06”N, 63°46’47”W, INHS 31365, 3, 2 cs, (79.2-96.6) . Río Guarapiche, Río Orinoco dr. Caicara, USNM 163168, 1, (102.9) . Portuguesa: Caño El Mamon, Río Portuguesa dr. 9 km SE of highway 5 on the road to La Quebrada, 09°07’20”N, 69°31’20”W, MCNG 12648, 2, (171.2-185.2) . Caño Iguecito, Río Portuguesa dr. on the road to Moritas, 08°38’00”N, 69°29’56”W, MCNG 30207, 1, (107.2) . Caño Igues, Río Portuguesa dr. 2 km from bridge at Paplón, 08°38’15”N, 69°59’45”W, MCNG 30163, 1, (164.8) . Caño Igues, Río Portuguesa dr. La Capilla, INHS 31966, 1, (97.4) . Caño Maraca, Caño Igues - Río Portuguesa dr. on road from Guanare to Guanarito at 60 km marker, 08°49’34”N, 69°20’45”W, INHS 35667, 2, (103.7-182.6) , MCNG 15696, 1, (131.0) , MCNG 8603, 2, (158.6-183.5) , and MCNG 27275, 1, (135.7) . Río Guanare, Río Portuguesa dr. Guanarito, INHS 31991, 1, (82.3) . Río Guanare, Río Portuguesa dr. on S side in Finca Merecure, approximately 45 min from Guanare on the road to Las Moritas, MCNG 33951, 1, (191.66) . Río Orape, Río Portuguesa dr. 45 km E of San Rafael de Onoto, 09°43’40”N, 68°30’10”W, MCNG 18716, 1, (108.0) . Tachira: Río Teteo, Río Apure dr. on road to El Nula, 07°28’40”N, 71°55’40”W, MCNG 8086, 2, (122.3-154.0) . Tributary to Río Doradas, Río Apure dr. La Pedrera, INHS 28153, 1, (87.2) .

Diagnosis: Hypostomus plecostomoides is the most difficult species of the H. cochliodon group to identify as it is without any known synapomorphies. The most similar species are H. hondae , H. pagei , and H. taphorni . Hypostomus plecostomoides differs from H. pagei by having spots on the caudal-fin spines (except in very melanistic specimens), by having darker overall coloration, a different juvenile coloration (Fig. 14A vs. Fig. 14B; see description of H. pagei ), and by generally having the pectoral-fin spines reaching 2-3 plates beyond the pelvic fin when depressed ventral to the pelvic fin (vs. 0-1; one specimen of H. pagei has the pectoral fin reaching two plates beyond the pelvic fin, and the single specimen of H. plecostomoides examined from the Lago Valencia drainage has the pectoral fin not extended beyond the pelvic fin); from H. hondae by having a lower number of plates in the skin around the dorsal-fin spine (Fig. 6A; Table 7); and from H. taphorni by lacking a bicolored caudal fin and by having no or medium to large spots on the abdomen (vs. small spots; Fig. 22; see Comments). Hypostomus plecostomoides can be distinguished from H. cochliodon by having a different color pattern (lacking a dorsal stripe and generally being well-spotted), from H. ericius and H. oculeus by lacking sharp keels, and from H. ericius , H. oculeus , and H. pyrineusi by having greater than 10 odontodes on the opercle.

Description: See Hypostomus cochliodon group description for more details. Morphometric data given in Table 4. Hypostomus plecostomoides is variable in coloration. Typically, body almost entirely dark brown with medium to large spots usually present. Spots on head fairly large compared to H. hondae , H. pagei , and H. taphorni . Spots increasing in size but fading posteriorly, spots absent on caudal peduncle (Figs. 21). Spots on abdomen typically large, but some specimens with medium-sized spots, spots never as small as in H. taphorni (Fig. 22). Spots occasionally entirely absent and entire fish dark brown (almost black). Caudal fin may be entirely spotted, but caudal-fin membrane and rays typically black or black distally and light proximally. Caudal-fin spines typically spotted although some specimens with entirely black spines; caudal fin not bicolored. Specimens from particularly muddy streams gray-brown, but not to extent seen in H. pagei . Abdomen colored as sides, sometimes slightly lighter; adults almost always with welldeveloped spots on abdomen. Color in juveniles as in adults, but spots comparatively larger and abdomen generally white and unspotted.

Dorsal fin short, rarely reaching preadipose plate when depressed. Depressed pectoralfin spine ventral to pelvic fin reaches 2-3 plates beyond pelvic-fin rays (only one specimen reached just to posterior edge of pelvic fin). Tip of pectoral-fin spine of nuptial males with stout, recurved, hypertrophied odontodes.

Keels weak to moderately developed. Orbits forming moderate ridge slightly raised above medial surface of head; ridges of dorsal and lateral aspect of head fairly well-developed. Longitudinal ridge on pterotic-supracleithrum beginning at posterodorsal corner of eye formed from raised bone and slightly larger odontodes absent. Opercle always supporting much more than ten odontodes. Nuptial body odontodes absent (Fig. 2A). Plates in skin anterior to dorsal-fin spine absent or few (Fig. 6A; Table 7).

Each jaw with 5-16 teeth (mode = 9), teeth large and spoon-shaped. Average angle between dentaries 57° (SD = 10°; range: 41°-82°; N=30). Lateral line plates 27-30; dorsal plates 7-9; interdorsal plates 6-8; adipose caudal plates 8-11.

Range: Found in the Río Orinoco basin of Colombia and Venezuela, and the Río Tuy and Lago Valencia drainages of Venezuela (Fig. 11). Hypostomus plecostomoides is allopatric to all other species of the H. cochliodon group (see Comments).

Comments: Specimens most appropriately identified as Hypostomus plecostomoides from the Orinoco drainage in northwestern Bolivar state, Venezuela ( ANSP 162345, MBUCV V-16855, MCNG 11176, and MCNG 22931), may provide evidence for intergradation between H. plecostomoides and H. taphorni . Some specimens from this region have the bicolored caudal fin diagnostic for H. taphorni , and few or no odontodes on the opercle and relatively smaller spots on the head than typical in H. plecostomoides . However, the specimens lack the second synapomorphy for H. taphorni , small spots on the abdomen. Alternatively, it is possible that these specimens represent an undescribed species. Additional specimens will have to be examined before the status of the members of the H. cochliodon group from northern Bolivar state can be assessed. For the purposes of this study, specimens from northern Bolivar were excluded from the description above and from Table 4.