Diagnosis: This species is characterized by uniformly dark brown pigmentation throughout the body, and extending onto the fins for 1/3 of their length; only the distal 2/3 of each fin lacks pigment, apart from the dorsal fins, which are dark brown (Ref. 93144). In addition, Typhleotris mararybe can be distinguished from congeners by the presence of prominent and protruding anterior skeletal elements: protruding lateral ethmoid, sphenotic, and pterotic projections, in combination with a strongly sunken and concave orbital region, lend the head a sculpted and angled bony appearance, particularly in dorsal view; a shorter pectoral fin not reaching a vertical through the anus when adpressed; and an elevated vertebral count (Ref. 93144). It is further distinguished from T. madagascariensis by the absence of scales fully covering the head and a longer second predorsal length (64.9-69.0% of standard length vs. 56.2-64.1% of standard length); and from T. pauliani by a shorter prepelvic length (33.0-33.9% of standard length vs. 34.1-40.4% of standard length), a pelvic formula of I,5, and the absence of a single leading spine in both the second dorsal and anal fins (Ref. 93144).

Description: A small, elongate and overall thin gobioid (Ref. 93144). Body wide anteriorly and head dorsoventrally compressed, particularly rostrally (Ref. 93144). Head bony, and sculpted in appearance, not fleshy, rounded, and smooth; toothed margins of both upper and lower jaws visible externally when mouth closed; inside mouth white; snout and anterior portion of head elongate and shovellike, with a bony, armored appearance, creating a duck-billed appearance; body becoming progressively laterally compressed posteriorly; caudal peduncle laterally compressed, shallow, and elongate; anterior nostril small, tubular, located near upper lip; posterior nostril short, somewhat slitlike and fleshy, but opening more or less oval (Ref. 93144). Mouth large, and gape wide; oral jaw teeth small, recurved, and conical; teeth numerous and arranged in six or seven closely set and irregular rows anteriorly in both upper and lower jaws; teeth tapering to fewer rows of somewhat smaller teeth posteriorly, as well as medially proximal to synthesis, where tooth rows become noticeably reduced in number and constricted, in both upper and lower jaws; teeth present along full length of premaxillary arcade and dentary; porelike structures present on basihyal (Ref. 93144). Head asquamate, except scales extending anteriorly onto roof of neurocranium and also covering operculum; although scales on top of head do not extend nearly as far forward as in Typhleotris madagascariensis, squamation does extend to anterior margin of neurocranium, but scales do not extend anteriorly onto snout (Ref. 93144). Otherwise, body fully scaled to the caudal fin, including chest region anterior to the pelvic fin and inner margin of pectoral fin; cycloid scales present ventrally on chest and belly; scales cycloid on body, except operculum, which is covered with strongly ctenoid scales; all other scales on body appear to be cycloid; scales arranged in irregular rows, uneven in size, with smallest on roof of head and largest on operculum; fleshy pectoral base covered with ctenoid scales; pectoral-fin axil asquamate (Ref. 93144). Two dorsal fins; first dorsal fin with 5 spines and second dorsal fin with 8 rays; anal fin with 8 rays; pectoral fin with 14-15 rays (Ref. 93144).

Colouration: Body uniformly dark brown; all fins dark brown proximal to base, whereas distal 2/3 of caudal, pelvic, pectoral, and anal fins depigmented and white; first and second dorsal fins more or less dark brown (Ref. 93144). In alcohol, the white coloration on the distal portion of the fins becomes an opaque off-white, whereas the dark brown base coloration of the body remains more or less unchanged (Ref. 93144).