Holotype : [Belgian] Congo: 45 mi. E Kama [Province of Maniema, DR Congo], 750 m, VIII-16-57/E.S. Ross & R.E. Leech collectors (California Academy of Sciences; Fig. 6); 1♀.

This species is characterized by the basal cuticular sculpture and larger sparse punctures of the female clypeus, the substantially depressed area above the antennal sockets, elongated scape, thin gena, silvery-yellowish pubescence and setae of the head, mesosoma and metasoma, with angulate and coarsely punctate T1.

Female. Wing length: 8.9 mm.

Head. Head in frontal view barely wider than high (Fig. 1). Clypeus about as wide as long (Fig. 1). Juxtamandibular lobes weakly developed, with shallow excavation (Fig. 1). Clypeal apex projecting well above juxtamandibular lobes, with acute tip (Fig. 1). Clypeus surface with basal sculpture and evenly spaced and well-defined smaller punctures (biphasic punctation pattern), thus resembling numerous Polistes Latreille species, but not Ropalidia (Fig. 1). Lower half of inner orbit impunctate, upper half with large and coarse punctures (Figs 1, 2). Entire area above antennal sockets markedly depressed; clypeal surface very flattened in lateral view (Fig. 2). Interantennal area elevated and flattened, covered by a punctation same as on clypeus (Fig. 1). Frons coarsely punctate, with weakly bent silvery-yellowish setae that are somewhat shorter than ocellar diameter (Fig. 3). Gena coarsely punctate, punctures diminished close to the occipital carina (Fig. 3). Gena at most half width of the compound eye (Fig. 3). Occipital carina sinuate and complete, reaching mandible (Fig. 3). Interocellar area raised posteriorly, with punctuation similar to that on frons; distance between posterior ocelli about 1.7× as long as distance between anterior and posterior ocellus. Distance between posterior ocellus and occipital carina as long as 0.6× of distance between posterior ocellus and inner eye margin. Eyes asetose (Fig. 2). Scape conspicuously elongate, about twice as long as AF1. AF2 as long as wide (Fig. 1), remaining flagellomeres wider than long; AF8 about twice as wide as long (Fig. 2).

Mesosoma . Mesosoma about 1.4× as long as wide. Pronotal carina complete and sharp, about equally wide laterally and dorsally, broadly rounded on humerus. Pronotum largely and coarsely punctate, punctures merge and create a punctation network close to inferior pronotal angle. Mesonotum 1.15 × as long as wide between tegulae in dorsal view, distinctly convex in lateral view, so that anterior third is below level of posterior margin. Median mesonotal suture thin and elongate, reaching more than half of mesonotum length. Mesonotum sparsely and shallowly punctate, punctures more than one diameter apart, shrinking in size towards scutellum. Scutellum flattened, without median carina, coarsely punctate, punctures about twice as large as those on mesonotum. Metanotum flattened and as wide as scutellum, anterior two thirds coarsely punctate, posterior third inflexed downwards and shiny; lateral metanotal angles rounded, but well-developed. Mesopleuron markedly convex, very coarsely punctate, punctures become reticulate dorsally; epicnemial carina very well developed and dull. Metapleuron with very large and shallow punctures close to anterior margin; punctures become smaller laterally, only to increase in size on lateral side of propodeum. Dorsal propodeal carina weakly developed and barely visible underneath pubescence, without inferior carina. Propodeal excavation shallow, shallowly punctate dorsally, impunctate and weakly striated ventrally. Entire mesosoma covered by short silvery-yellow pubescence (about half length of anterior ocellus diameter), with somewhat longer whitish setae on propodeal excavation. Second submarginal cell wide, with elongate median angle.

Metasoma . T1 about half width of T2 in dorsal view, strongly angulate in lateral view, enclosing angle of about 110° (Fig. 4). Anterior half dorsally inconspicuously, minutely punctate, laterally deeply and coarsely punctate. T2 1.2× as long as wide, with parallel sides. T2 and S2 shallowly punctate, with punctures gradually increasing and becoming large and coarse in centre of S2. T2 lamella yellow and translucent (Fig. 4). T2 covered by golden pubescence and yellowish protruding setae that extend over the lamella (Fig. 4).

Colour. Basal colour black (Fig. 1). Clypeus tricolourous, with black border, brown basally attached median spot nearly reaching apex, yellowish-white laterally (Fig. 2). Smaller yellowish spot adjacent to inner orbit, reddish-yellow interantennal area, mandible whitish with brown tip and blackish basal area (Figs 2, 3). Scape dark brown dorsally, ferruginous ventrally (Fig. 2). Flagellum dorsally blackish, ventrally reddish, with several distal segments orange ventrally (Fig. 3). Pronotum with thin yellow line underneath carina (Fig. 4), scutellum faint reddish postero-laterally, metanotum with two large yellow spots occupying two thirds of total surface, propodeum entirely black (Fig. 1). Legs black, femora with thin reddish line on inner side; tarsi somewhat darker. Wings infuscated, with moderate darkening in tip of basal cell and majority of marginal cell (Fig. 5). T1 with reddish-yellow triangular mark laterally (Fig. 5). T2 with complete posterior yellow band, S2 with partial posterior band (interrupted medially); remaining terga and sterna black.

Figures 1–6. 

Ropalidia chromis sp. nov., female 1 head, frontal view 2 head, oblique view 3 head, lateral view 4 T1 and T2, lateral view 5 habitus, dorsal view 6 holotype labels.

Male is unknown.

The name is a Latinized form of “chrome”, a noun in apposition, with reference to the silvery-yellowish setae and pubescence of the head, mesosoma and metasoma.

Democratic Republic of the Congo.

This species exhibits features seen in both capensis- and non-capensis-groups (Table 1). In addition, several features do not resemble either and present apparently autapomorphic features sufficient for species determination, including the depressed area above the antennal socket and a biphasic clypeus punctation (Table 1).