This species is distinguished from its congeners by the following characters: absence of the abdominal keel and prepelvic serrae formed by 13-19 low spines (vs. a well-marked abdominal keel and prepelvic serrae of more than 20 high spines). It differs from asterias, levis, torquatus by having fewer branched dorsal-fin rays 20-22 (vs. 23 or more); from arnoldi, ternetzi, torquatus by having a greater number of branched anal-fin rays 32-34 (vs. 31 or fewer); differs significantly from lobatus, schomburgkii, rhomboidalis by having two rows of premaxillary teeth forming a slight arc (vs. 2 rows of premaxillary teeth forming a shape that resembles the uppercase letter 'A'; shorter dorsal-fin base 27.6-30.1% of SL (vs. 31.8% of SL or higher); differs from asterias, levis, ternetzi, torquatus in having a larger interdorsal distance 11.4-12.7% of SL (vs. 10.8% of SL or lower); differs further from M. ternetzi by the presence of a pair of symphyseal teeth (vs. none); from asterias, levis, lobatus, ternetzi by having a smaller vertical diameter of the eye 27.3-35.4% of HL (vs. 35.5% of HL or greater); from arnoldi, torquatus by having a greater number of total vertebrae 40-41 (vs. 37 or less), by having anterior dorsal-fin rays lacking pigmentation (vs. strongly dark pigmented), and the presence of a diffuse dark band at caudal-fin distal border (vs. the presence of a well-defined dark band); from M. asterias by having an elongated fontanel with similarly sized anterior and posterior portions (vs. very short posterior fontanel and rounded anterior fontanel) (Ref. 114773).