Leucoraja longirostris, the brown longnose skate, is a medium-sized species of the genus Leucoraja with disc rhombic to (in adult male) evenly inverse heart-shaped, with broadly rounded outer corners and with body length to mid-vent about equal to tail length from mid-vent. Preorbital snout length 17.2–22.3% TL and distance between first gill slits 11.6–12.9% of TL. Orbits moderately large, horizontal diameter 1.0–1.2 times interorbital width. Dorsal disc largely devoid of denticles, ventrally spinules at least on snout tip. Thorn pattern pronounced with ~5–20 rostral thorns, a half ring of 3–5 thorns on each orbital rim, 1 supraspiracular and 1 interspiracular thorn per side, 3–5 median nuchal thorns, 0–3 lateral nuchal thorns per side, 1–2 suprascapular thorns, 0–2 lateral scapular thorns, 2–3 scapular thorns per side, a median row of 34–41 thorns from behind the shoulder girdle to just before the origin of the first dorsal fin, no interdorsal thorns, and 2–4 parallel rows of thorns on tail. When fresh, dorsal surface plain medium-brown, with grayish mucus coverage; ventral side plain grayish on disc and pelvic fins, snout dusky grayish, sensory pores not marked dark. Bases of nearly equal-sized and long but low dorsal fins confluent or with short interspace of maximally 0.8% TL. Postdorsal tail section short, 2.5–3.8% TL, with low epichordal caudal lobe, which is confluent with the second dorsal fin. Brownish lateral tail folds along posterior 58.1–72.0% of tail. Upper jaw tooth rows 41–49, pectoral-fin radials 69–73, pelvic-fin radials 3 + 15–3 + 18. Clasper lacking external pseudosiphon; inner dorsal lobe with components roll, promontory, slit, and two clefts; inner ventral lobe with components shield, rhipidion, pent, sentinel, spike, and dike. Terminal clasper skeleton with four dorsal terminal cartilages, a ventral terminal, and two accessory terminal cartilages, plus a tiny separate spindle-shaped fibrocartilage between distal tips of dorsal terminal 1 and ventral terminal.