Additional photos below
Head Pores - Cephalic lateral canal system with pores B',D,F,G,H' pore, G sometimes lacking; preopercle canal with two pores.
Scales - lateral scale rows about 46-60; scales on sides extending forward to about midway beneath the appressed pectoral fin, absent on dorsum immediately below anterior part of spinous dorsal fin. Scales ctenoid over most of body, cycloid on dorsum below posterior part of spinous dorsal fin and on belly and venter above anal fin.
Fins - D1 - VII, 2-6 filaments produced in males, extending to or past caudal base, spines in females only slightly produced.
Head - fleshy nuchal crest well developed in females, smaller in males
Color - Male: preserved color - body dusky brown, slightly darker dorsally; a dark spot present on body below origin of spinous dorsal fin, spot bordered anteriorly and posteriorly by pale areas (spot variably developed in males); dorsum below dorsal-fin base marked with six dark dashes; pectoral base and head slightly darker than body; with larger melanophores; cheek, opercle, and area immediately posterior to eye somewhat mottled (probably brightly colored spots or stripes in life). Spinous dorsal fin dusky with pale basal and pale medial stripes, fin becoming darker distally, occasionally with smalll dark spot on first interradial membrane; soft dorsal fin dusky with submarginal pale stripe and narrow dark distal border; pectoral fins dusky; pelvic fin membranes uniformly and densely pigmented with melanophores; anal fin dusky with pale distal margin; caudal fin dusky with narrow dark marginal stripe dorsally and pale marginal stripe ventrally.
Female: pigmented as males except - ventral above anal fin devoid of melanophores (this pale area less well defined and less extensive than sililar pattern of female M. signatus); spot on body above pectoral base very dark and well defined, bordered anteriorly and posteriorly by pale bars, these bounded by narrow dark bars. Spinous dorsal fin dusky, often with small to large dark spot in the first, third, or fourth interradial membranes; soft dorsal fin dusky with median, pale stripe; pectoral fins dusky; pelvic fins dusky with pale border and a submarginal dark stripe; anal fin dusky, pale proximally; caudal fin with several large pale spots in dorsal half. (Birdsong 81)
Female - live color from Randall (in Birdsong 81): translucent dusky olive, the belly greenish yellow; a blue-edged black spot on back above pectoral base; some iridescent blue green markings on cheek and opercle; 2 lengthwise rows of faint iridescent blue spots on anterior half of body; 2nd dorsal fin with a basal red-orange band; above this, bands of blue, red, yellow and at the edge, orange-red; 1st dorsal with red outer margin and blue submarginal band; caudal dusky with 3 diaginal rows of red spots in upper part, a narrow median red band and some yellow ventrally.
Distribution - Puerto Rico, Venezuela south to Santos, Brazil
Habitat - shallow, mud-bottom mangrove areas
photos by B.M. Feitoza from NE Brazil