Beautiful Striolated Manakin is a species of bird in the Pipridae family. The striolated manakin or western striped manakin (Machaeropterus striolatus) is a small South American species of passerine bird in the family Pipridae. It is found in west and north west Amazonia. The striolated manakin was formerly considered conspecific with the kinglet manakin (Machaeropterus regulus) with the common name "striped manakin". Males have a bright red crown, which the females lack.

Long considered the same species as Kinglet Manakin (Machaeropterus regulus), these two species' respective ranges are far removed, with Striolated Manakin being confined to western and northern South America, from northern Peru and western Brazil, through eastern Ecuador and Colombia, north to western Venezuela and east to the Tepui region of southern Venezuela, with a single, 19th-century specimen, record in western Guyana.

In contrast, Kinglet Manakin is confined to the Atlantic Forest lowlands of eastern Brazil. This tiny-bodied manakin is uncommon to locally fairly common in the lower to middle levels of humid primary forests, as well as shade-coffee plantations and mature second growth, never higher than 1,500 m and mainly at elevations below 1,000 m. Whereas the female is uniform olive-green on the upperparts and mainly yellowish white below with reddish-brown streaks on the belly and flanks, the male is characterized by its glistening red coronal patch and whitish-streaked reddish-chestnut underparts with a yellow or red breast-band, the latter varying to some extent with race, of which five are recognized.

Like all manakins, males are divorced from all nesting duties; they display in exploded leks, wherein the different individuals (usually no more than three, occasionally as many as 11) are within earshot but not sight of each other, usually sited atop low hills. Each male possesses a number of favored perches, from which the bird calls intermittently throughout the day, but switches to making a series of short vertical jumps, each one accompanied by vibrating wing movements (employing the modified secondaries) and insect-like buzzing notes, should a female appear at the lek site. Populations of this species east and west of the Andes differ slightly in their vocalizations.

Male is olive above, with red cap and nape; secondaries stiffened and enlarged, with white tips; tail also stiffened, with thick rachi; throat whitish; rest of underparts reddish-chestnut, redder on chest side, with whitish shaft-streaks. Female lacks red on head, is entirely olive above, dingy whitish below, breast and sides pale olive with fine whitish streaks, breast side tinged brownish.

Once identified as a piprid, the streaked underparts become virtually diagnostic throughout this bird's distributional range. Differs from the allopatric and formerly conspecific Kinglet Manakin (Machaeropterus regulus) in its much broader pale purplish stripes on the underparts of males, whitish versus pinkish-white throat, lack of paler green panel in closed wing, and entirely different song, consisting of one versus two notes, with all comparable elements lower-pitched, and total length shorter. In parts of southwest Amazonia, in particular, the present species' range overlaps with that of the Fiery-capped Manakin (Machaeropterus pyrocephalus), the male of which has a very different coronal pattern (appearing mainly yellow when seen side-on) and shows much less and weaker streaking on the underparts, while the female displays only very subtle streaking below, and this is confined to the mid-belly.

Plumages,Juvenile And Molts: Nestling is undescribed. Juvenile plumage is basically identical to that of the adult female, but young males quickly gain a few red feathers (which are basally white) on the rear crown. Very little published information. The following pertains to populations in central and eastern Colombia (races antioquiae and the nominate); molting females have been trapped in April, September and December, and males in April–July and September–November.

Male. Ear-coverts, most of upperparts, and tail are bright olive-green, with a bright glistening red crown, forming a flattened crest. Remiges grayer than the rest of the upperparts, with white tips to the tertials and inner webs of the flight feathers, although these are extremely difficult to see in the field. Secondaries are modfied, with the tips being thickened and enlarged.

Chin and throat buff or whitish, and whitish below and heavily, extensively and broadly streaked red (but racially variable). Stained either red or yellow on upper breast (again varies with race). Underwing-coverts are generally white, but can be stained cinnamon (perhaps varies geographically)

Female. Has uniform olive-green upperparts, again with white inner fringes to the tertials. Throat buffish white, and rest of underparts yellowish white, coarsely streaked reddish brown on the belly and, especially, on the flanks.