Diagnosis: Chiloglanis tweddlei is distinguished from C. waterloti, C. normani, C. occidentalis, C. nzerekore, C. longibarbis, C. kabaensis, and C. kolente in having more mandibular teeth in the functional row; it can be easily distinguished from C. polyodon and C. lamottei in having fewer mandibular teeth in the functional row, and from Chiloglanis aff. micropogon in having moderately long medial and lateral mandibular barbels vs. absent or reduced barbels; it is distinguished from C. dialloi, C. loffabrevum, and C. camarabounyi in having longer dorsal and pectoral spines; it can be distinguished from C. pezoldi in having a wider premaxillary tooth patch, 15.3-18.2% of standard length vs. 12.2-15.8%, and in having more premaxillary teeth in four rows vs. fewer teeth in three rows (Ref. 116018).
Description: A moderate-sized Chiloglanis; 56.0 mm maximum observed standard length; body dorsally depressed anteriorly; laterally compressed posteriorly; pre-dorsal profile convex; sloping ventrally to snout; post-dorsal profile nearly horizontal; sloping ventrally towards caudal fin; pre-anal profile nearly horizontal; convex towards oral disc; post-anal profile concave towards caudal fin (Ref. 116018). Small unculiferous tubercles scattered across body; more concentrated on dorsum and head; lateral line complete; arising above level of orbit and sloping ventrally towards caudal fin; urogenital papillae sexually dimorphic; elongate in males; reduced and separated from anus by shallow invagination in females (Ref. 116018). Head depressed; gill membranes broadly united; gill openings restricted; opening from pectoral-fin origin to level of orbit; occipital-nuchal shield covered and visible through skin; eyes moderate; located mid-head length; horizontal axis longer; without free margins; anterior and posterior nares located mid-snout; posterior nares slightly further apart than anterior; posterior nares with elongated medial and anterior flaps (Ref. 116018). Mouth inferior; upper and lower lips united to form oral disc; oral disc moderate, its width 20.7-24.5% of standard length; wider than long; covered in papillae (Ref. 116018). Barbels in three pairs; maxillary barbels originated from posterolateral region of the disc; unbranched; moderate in length, 18.9-32.0% in head length; lateral and medial mandibular barbels moderate; incorporated into lower lip and positioned on both sides of midline cleft on posterior margin of oral disc; lateral barbels, 10.3-15.5% of head length, nearly twice the length of medial barbels (Ref. 116018). Primary premaxillary teeth "S"-shaped with exposed orange-brown tips; 42-104 teeth in four rows on two ovoid tooth patches; secondary premaxillary teeth fewer; scattered on posterior surface of premaxillae; tertiary teeth sharp and needle-like; bunched near midline of dorsal edge of toothplate; mandibular teeth in 1-2 rows; "S"-shaped and bunched near symphysis; functional, anterior, row usually contains 12 brown-tipped teeth (Ref. 116018). Dorsal-fin origin posterior to anterior third of body; dorsal fin with small spinelet, spine, 4-6 rays; dorsal spine relatively long, 16.0-22.5% of standard length; anterior edge with small notches distally; posterior edge of spine larely smooth; adipose fin moderate in length, 14.4-19.5% of standard length; margin convex with notch at terminus; caudal fin forked with rounded lobes; lower lobe longer than upper lobe; count i,7,8,i; anal-fin origin posterior to vertical of adipose-fin origin; margin convex; count iii,6-7; pelvic-fin origin at midway between dorsal-fin terminus and adipose fin; extending to anal-fin origin; margins convex; count i,6; pectoral fin with smooth spine, relatively long, 17.5-25.4% of standard length; count I,8 (Ref. 116018). Postcleithral process sexually dimorphic; males with elongate, spatulate process; females with shorter, more bluntly pointed process (Ref. 116018).
Colouration: In dorsal view, body dark brown; mottled areas of medium brown pre-orbital, at dorsal-fin origin, and at the origin and terminus of the adipose fin; small light unculiferous tubercles concentrated on head and dorsum; in lateral view, light cream-buff with overlain darker areas; lighter area at terminus of adipose fin extending ventrally to anal-fin terminus, melanophores across side, more apparent over lighter areas; in ventral view, body cream; dark areas near anal-fin origin, belly and chest covered in melanophores; oral disc and barbels cream (Ref. 116018). Pectoral and dorsal spines cream to translucent; dark triangular patches at bases of dorsal and pectoral fins; melanophores at mid-length of dorsal and pectoral fins; creating faint bars; pelvic fin cream; few melanophores at base and mid-length; adipose fin cream to translucent; dark area at origin and near base at mid-length; anal fin with dark brown triangle at base and small markings at mid-length; caudal fin cream to translucent; two darker areas on the upper and lower lobes (Ref. 116018).