Trichomycterus hualco Fernández & Vari 2009

This species is distinguished from its congeners, with the exception of T. areolatus by having a relatively low number of odontodes 1-14 (vs. 16 or more) on the opercle (apparent in cleared-and-stained specimens and on the interopercle 2-20 (vs. 28-40), and by the extent of development of the integument on the interopercle (integument thin and not enveloping odontodes on the interopercle vs. integument thick with odontodes embedded in integumentother than in smaller individuals). This new species differs from T. areolatus by the number of total vertebrae 33-34 (vs. 37- 39); the area of insertion of the first proximal dorsal-fin pterygiophore is posterior to neural spine of vertebra 16 or 17 (vs. vertebrae 20-22); supraorbital canal segment and pore So3 continuous, with pore So3 absent (vs. discontinuous with pore So3 present); the papillae-like structures on the body present (vs. absent). It is further distinguished from all congeners, with the exception of T. corduvensis fromArgentina and T. therma and T. tiraquae from Bolivia, by the its possession of elongate premaxillary teeth with the distal portion of each tooth flattened and slightly expanded; presence of papillae-like structures on the body; continuous supraorbital canal within the frontal with the presence of a segment between pores So2 and So6 (but with pore So3 missing); long lateral line canal with 4 pores. Also if differs with its congeners in the caudal peduncle depth 8.4-11.3% SL (vs. 11.9-13.2% SL in T. corduvensis); in head width 19.1-21.8% SL (vs. 17.4-19.0% SL in T. tiraquae ) and nearly completely in the distance from the tip of the snout to the insertion of the pelvic fin 57.4-61.9% SL (vs. 56.6-57.6% SL in T. tiraquae); in the degree of development of the transverse skin on the ventral surface of the head not thickened (vs. distinctly thickened in T. therma) (Ref. 80457).

Dorsal soft rays (total): 14 - 16; Analsoft rays: 10 - 11; Vertebrae: 33 - 34

Inhabits a small, clear water stream that flows down a small rocky canyon into a small pool. Stream and pool depth range, approximately 0.2 to 0.6 m deep and 1.0 to 1.5 m wide; both had rock and pebble bottoms and with limited adjoining terrestrial vegetation among the surrounding boulders. The type locality (Río Hualco) seeps into the soil downstream from the pool and is apparently isolated from adjoining drainages throughout the year. The specimens were collected both above and below an approximately three-meter high waterfall within the stream and in the pool, none were observed in the small outflow stream that drains the pool. Stomach contents include dipteran larvae (Chironomidae and Ceratopogonidae), this diet of autochthonous benthic macroinvertebrates is common to species of Trichomycterus. T. alterus was also collected from this site. Local inhabitants utilize the Río Hualco as a recreation site and on occasion as a bathing area, hence such activities put it at risk of ecological alteration, a threat common to many other aquatic habitats within those portions of the Andes especially for this species, given its apparent restriction to that small drainage system (Ref. 80457).

Inhabits a small, clear water stream that flows down a small rocky canyon into a small pool. Stream and pool depth range, approximately 0.2 to 0.6 m deep and 1.0 to 1.5 m wide; both had rock and pebble bottoms and with limited adjoining terrestrial vegetation among the surrounding boulders. The type locality (Río Hualco) seeps into the soil downstream from the pool and is apparently isolated from adjoining drainages throughout the year. The specimens were collected both above and below an approximately three-meter high waterfall within the stream and in the pool, none were observed in the small outflow stream that drains the pool. Stomach contents include dipteran larvae (Chironomidae and Ceratopogonidae), this diet of autochthonous benthic macroinvertebrates is common to species of Trichomycterus. T. alterus was also collected from this site. Local inhabitants utilize the Río Hualco as a recreation site and on occasion as a bathing area, hence such activities put it at risk of ecological alteration, a threat common to many other aquatic habitats within those portions of the Andes especially for this species, given its apparent restriction to that small drainage system (Ref. 80457).