Image 1. Akysis portellus sp. nov., ZRC 51138, holotype, 32.7mm SL; dorsal, lateral and ventral views.

Image 2. Anterior views of: a - Akysis portellus sp. nov., ZRC 51139, paratype, 33.3mm SL; b - A. longifilis, ZRC 51157, 30.6mm SL, showing differences in gape widths.

Image 3. Dorsal views of heads of: a - Akysis portellus sp. nov., ZRC 51139, paratype, 33.3mm SL; b - A. longifilis, ZRC 51157, 30.6mm SL, showing differences in shape.

Image 4. Akysis portellus sp. nov., ca. 31mm SL (specimen not preserved), showing live coloration.

Image 5. Akysis portellus sp. nov., UMMZ 248469, paratype, 30.4mm SL, showing orange hue present on head and body of some individuals.

Table 1. Biometric data for Akysis portellus sp. nov. (n=10)

	Holotype	Range	Mean+SD
%SL
Predorsal length	35.2	33.8–38.1	36.1+1.5
Preanal length	64.8	64.0–69.2	66.5+1.9
Prepelvic length	45.6	45.6–51.4	48.2+2.5
Prepectoral length	23.2	20.1–23.2	21.7+1.2
Length of dorsal-fin base	14.1	12.6–14.1	13.4+0.7
Dorsal-spine length	13.1	13.1–15.9	13.9+1.1
Length of anal-fin base	14.7	12.7–15.6	14.6+1.1
Pelvic-fin length	15.0	12.9–15.0	13.8+0.8
Pectoral-fin length	22.6	22.0–24.5	23.2+0.9
Pectoral-spine length	15.0	14.3–16.3	15.5+0.7
Caudal-fin length	21.1	20.5–24.8	22.8+1.8
Length of adipose-fin base	18.7	17.1–19.2	17.9+0.9
Caudal peduncle length	20.8	19.1–22.0	20.6+1.3
Caudal peduncle depth	7.0	6.0–7.0	6.7+0.4
Body depth at anus	15.3	12.0–15.3	13.6+1.1
Head length	23.9	21.8–27.0	24.7+1.7
Head width	22.6	22.6–26.7	24.4+1.5
Head depth	14.4	14.4–17.4	15.9+1.3
%HL
Snout length	39.7	31.7–40.3	37.0+3.9
Gape width	9.5	9.5–11.1	10.0+0.6
Interorbital distance	30.8	30.8–36.8	34.2+2.3
Eye diameter	10.3	8.8–12.5	10.3+1.3
Nasal barbel length	89.7	80.5–101.4	89.4+7.4
Maxillary barbel length	143.2	116.7–143.2	127.3+9.8
Inner mandibular barbel length	59.4	53.7–79.2	65.3+10.3
Outer mandibular barbel length	110.3	101.1–127.8	113.1+8.7

Figure 1. Type localities of Akysis portellus sp. nov. (triangle) and A. longifilis (circle).