Characteristics
Melanoclusia
is unusual in appearance, differing from Clusia (the most closely related genus) and all other Clusiidae in having only one pair of dorsocentral bristles, no dorsal preapical tibial bristles, a vibrissa-like anterior genal bristle, a shiny frons with no interfrontal bristles, a rounded frons and face, a white vein dm-cu and dark colouration. The external male genitalia are similar to those of Clusia, but the internal components are unusual in that they are extremely elongate, projecting far into the abdomen.                    

Relationships
Reduced postverticals and male-specific characters support a relationship with Clusia, but Melanoclusia bivibrissa lacks all of the distinct external synapomorphies used to separate that genus from other Clusiidae (interfrontal bristles, pubescent arista and striped scutellum). It is for this reason that Melanoclusia bivibrissa is treated as the sister group to Clusia and not a highly derived basal species of Clusia. The male characters supporting a relationship between Melanoclusia and Clusia include the following: two rows of posteroventral bristles on the fore and mid femora (also found in the Chilean Clusiidae and Clusiodes), an inner-basal spur on a small, triangular surstylus, a uniquely-shaped pregonite (long, thin, minutely setulose along length and closely-associated with base of phallapodeme) and absence of the lateral lobes of the distiphallus (independently lost in some Sobarocephalinae and most Clusiodinae).

Melanoclusia Lonsdale & Marshall is represented by the single species M. bivibrissa Lonsdale & Marshall, which is known from only one male and one female from Borneo. While not observed in the field, the unusual colouration and chaetotaxy of this species suggests that behaviour plays an important role as a secondary sexual character – this has been documented in many other species of Clusiidae with similar morphology, including those in the behaviourally fascinating Heteromeringia Czerny, Clusiodes Coquillett and Hendelia Czerny.

North American species: None.