Ropalidia chromis Polasek 2024

Ropalidia chromis Polašek, 2024 male Figs 1, 2, 3, 4 A; female Fig. 4 B Material examined. Democratic Republic of the Congo • 4 ♀♀, 1 ♂; Mbandaka; “ MUSEE DU CONGO / Eala, I 1936 / J. Ghesquiere / 2041 ”, (“ R. DET. E 4938 ”); RMCA • 1 ♀, 1 ♂; Mbandaka; “ MUSEE DU CONGO / Eala, – 1936 / J. Ghesquiere / 23781 ”; RMCA Observation. Republic of the Congo • 2 ♀♀, nest; Mbandaka Odzala-Kokoua, Ouesso; 0.75775°N, 15.25975°E; 24 Nov 2023; obs Emily Rampling; (Rampling 2023) New record for Republic of the Congo. Description. Males. Wing length 8.7–9.1 mm. Head. Head frontally 1.35 × as wide as long (Fig. 1 A), in dorsal view 2.6 × as wide as long, not narrowing behind eyes, barely emarginate posteriorly (Fig. 1 C). Clypeus 1.4 × as wide as long (measured as transversal distance between oculo-clypeal angle against distance from the basal emargination to apex), with very elongated base with streamlined upes that continues directly into lateral margin of clypeus and very elongated interantennal area that reaches apical half of clypeus; juxtamandibular excavation very shallow, apex barely pointy (Fig. 1 B). Clypeus surface with cuticular texture, impunctate (Fig. 1 B). Frons sparsely and coarsely punctate, punctures 2 × diameter apart, with matt interspaces; inner orbit and interantennal area impunctate, eye sinus similarly punctate to frons; area in front of forward ocellus more densely punctate (Fig. 1 A). Distance between antennal sockets 1.2 × as long as socket-eye distance (Fig. 1 A). Occiput anteriorly with similar punctures to those on frons, posteriorly impunctate and shiny (Fig. 1 C). Gena with similarly sized and shallower punctures, more or less retained even close to occipital carina; occipital carina complete, mostly streamlined or barely sinuate in lowest third (Fig. 2 A). Mandible moderately tortuous, shiny, with only a few poorly-defined craters. Posterior ocelli 1.8 × diameter apart, 3.25 × diameters apart from eye and 2.2 × diameters apart from occipital carina (Fig. 1 C). Scape barely widened, 3.4 × as wide as long, 1.8 × as long as AF 1; AF 2 1.1 × as long as wide (measured as mid-length over mid-width), remaining flagellomeres gradually wider (Fig. 1 A), AF 6 – AF 8 widest, with AF 8 1.4 × as wide as long; AF 11 1.7 × as long as wide (measured as linear distance from base to tip divided by base width), with curved shape and subacute tip (Fig. 2 B). Tyloids originate as a small blackish spot on AF 2, gradually increasing in size, initially visible as trichome clearing on AF 5, more developed on distal flagellomeres (Fig. 2 B); tyloids hardly discernible from flagellomere surface, with depressed area until AF 10, where it is larger, dorsally elevated above flagellomere surface and shiny (Fig. 2 C); AF 11 tyloid shiny, linearly narrowing towards tip (Fig. 2 B). Mesosoma. Mesosoma slender, dorsally 1.15 × as long as wide in dorsal view, 1.1 × as wide as widest part of head (Fig. 1 C). Pronotum slender, with barely excavated area in dorsal view, lobes weakly developed, humeri rounded or just barely angled, pronotal carina laterally well developed, dorsally gradually lowering, medio-dorsally flattened into triangular evanescent area (Fig. 1 C, D); pronotum punctures coarse and large, diameter apart, somewhat smaller dorsally and larger inferiorly, with swollen and matt interspaces that create network inferiorly; punctures near mesoscutal margin small, mediodorsally very shallow or just in traces (Fig. 3). Disc of mesoscutum 1.05 × as long as wide, linearly narrowing anteriorly; mesoscutum sparsely punctate, punctures 1.5–2 × diameter apart, with cuticular / matt interspaces; puncture density retained throughout entire mesoscutum (Fig. 1 C). Mesepisternum with huge and confluent punctures creating network (Fig. 2 D) and rendering strongly carinated margin from anterior impunctate surface (anterior mesepisternum surface can have a few isolated punctures); posterior part of mesepisternum with small and spaced punctures; mesepimeron without vertical carina towards mesepisternum (Fig. 2 D). Metepimeron coarsely and horizontally striate, metepisternum with cuticular surface and some poorly-defined punctures anteriorly (Fig. 2 D). Disc of scutellum quadrate, 2.1 × as wide as long, with sparse punctures and cuticular interspaces, discernible median depression and short median carina, that extends on anterior surface and reaches about one-quarter of scutellum width; disc of metanotum quadrate, 2.7 × as wide as long, with two paramedian sinuate arches (Fig. 2 E). Propodeum linearly narrowing towards valvula, with shallow median depression, inferiorly striate, superiorly punctate, puncture size large but poorly defined (Fig. 2 E); lateral face of propodeum coarsely punctate (Fig. 2 D). Tarsal spur I developed, with broad base, about 2 × as long as wide, weakly tortuous. Metasoma. T 1 wide and angular, dorsal and posterior face at right angle in lateral view (Fig. 3 A); posterior face coarsely punctate, with punctures 1.0–1.5 × diameter apart and swollen cuticular interspaces; T 2 with somewhat smaller and substantially shallower punctures, with caudally directed shallowing (Fig. 3 A). T 2 and S 2 curvature similar, suture between them visible for over half of segment length; T 2 lamella translucent and yellow; transition between T 2 surface and lamella gradual, lamella very weakly punctate proximally, distal two thirds impunctate; remaining metasomal segments shallowly punctate. Pilosity. Body with short yellowish-silvery pubescence; clypeus (notably denser apically), interantennal area, inner orbit, low gena, mandible and lateral parts of mesosoma with silvery (Fig. 3 A), frons, occiput, mesosoma dorsally and metasoma with yellowish. Clypeus without protruding setae, only with underlying silvery pubescence, frons setae 0.6–0.8 × as long as forward ocellus diameter; pubescence on pronotum shorter than that on frons, mesoscutum with microscopic pubescence and no protruding setae (Fig. 2 A); remaining parts of metasoma with very short pubescence, expect lower half of propodeum with somewhat longer protruding setae (Fig. 2 E). T 1 and T 2 with minute pubescence and no protruding setae (Fig. 3 A), S 3 – S 6 with gradually lengthening protruding setae, terga with shorter setae. Colour. Basally black, except yellow face, mandible (Fig. 4), coxa I – III and posterior band on T 2; suffused brownish-reddish-yellow lower and medio-dorsal part of pronotum, scutellum and metanotum, posterior band on T 1, femur and tibia, tarsi dark-brown (Fig. 4). Wings smoky transparent, venation brown, stigma brown and opaque, apical spot and anterior margin more infuscate (Fig. 4). Nest. One nest was observed, from Odzala-Kokua region (Rampling 2023). The nest was in the early colony stage, with 13–18 cells (impossible to define due to the obscured side), with a compact cell wall, two elongated cells with dark-grey cocoon caps and additional pulp on them. The nest was located on a broad leaf, but the orientation is difficult to ascertain. Two adult females were observed on the nest, and there were no additional details available. Comparative notes. The examination of concomitant males and females confirmed unique characteristics of this species within the entire genus, which include rounded humeri with medio-dorsally evanescing pronotal carina, huge punctures high on mesepimeron with strong horizontal striae on metepimeron, with angular and coarsely punctured T 1. The male characteristics did not provide much support towards group membership, since males have tarsal spur I (characteristics of capensis group), but it has a broader base than in all examined species from that group. Next, males have low tyloids, which are even depressed in AF 5–9, while most of capensis group species have elevated tyloids above flagellomere surface. The distance between antennal sockets was shown to be a higher-order feature that splits the capensis and non- capensis groups (Polasek et al. in press). The antennal socket distance is 1.2 × as long as their diameter in R. chromis, which is similar to average (“ ancestral ”) of the non- capensis group, and contrasting with the average of the capensis groups with 1.0 × socket diameter. Lastly, the shape of frons in both males and females (Fig. 3 B) is unique, with depressed peri-antennal and median area, contrasting with all other African Ropalidia that have flattened frons. All this contributes to the proposal that this is the third lineage in African Ropalidia (Polasek 2024), one that might be close to the ancestral form for these two groups, as it exhibits characteristics of both of them.