Ropalidia tomentosa ( GERSTAECKER 1857 )

Ropalidia tomentosa ( GERSTAECKER 1857) View in CoL

Icaria tomentosa GERSTAECKER 1857

Type material. A holotype specimen was examined in MFNB ( Berlin ). The label indicates “Tette, Mozambique ” as the type location, which suggests the North-Western region of Mozambique. In addition, there is another label, “3550”, probably showing the number of the specimen, similarly to another type from the same series, that of R. nobilis (GERSTAECKER) .

Diagnosis.A larger species,with longer and rather specific pubescence, globular T1 and black tarsi, phenotypically resembling R. fita sp. nov. It is characterized by the black apical spot and brown fore wing nervature, in contrast to more yellowish apical spot and nervature in R. fita sp. nov. Males are described here for the first time.

Males.

Material. Multiple specimens from the entire distribution range of Sub-Saharan Africa. The total number of examined specimens: 51♂♂.

Diagnosis. Males of this species are among largest examined Ropalidia specimens. Their general appearance is rather dark, with stronger contrasting yellow areas and a dark fore wing apical spot (as opposed to males of R. fita sp. nov., that have a brownish spot and yellowish wings).

Description. Wing length: 9.1–12.1 mm. Colour. Resembles females, but similarly to most Polistinae , males have more yellow markings ( Figure 68a View FIGURE 68 , Figure 106c View FIGURE 106 ). Melanic specimens have basal body black colour with silvery-yellowish pubescence, while xanthic can have brown body colour and yellowish-golden pubescence (notably, both forms are sympatric from Zambia to Kenya, suggesting that this is likely not a speciation feature, but a variation of phenotype). Regardless of general colour pattern, markings are constant across entire distribution range. Clypeus, mandible, inner orbit and interantennal area primarily yellow ( Figure 68a View FIGURE 68 ; posterior area of mandible can have black line in melanic specimens); gena with thin yellow line, frons black, tempora and vertex reddish (vertex sometimes black). Pronotum with basal body colour dorsally, area under pronotal carina, inferior angle and posterior margin has reddish tone (often creating V-shaped reddish markings on pronotum, that may sometimes have yellowish angle). Mesonotum commonly in basal colour, sometimes with reddish markings close to tegulae, which can also be reddish. Anterior surface of mesopleuron yellow, lateral surface black (sometimes with a reddish area), metapleuron always black. Scutellum either with basal colour or with posterior reddish line, metanotum and propodeum black. All coxa pairs with yellow markings (melanic specimens can have black coxa III), femora variable, tibia commonly reddish, tarsi black. T1 often with reddish markings, T2 with basal colour and a thin posterior reddish or yellow line, T3–7 and S3–7 ferruginous or brown, but more lightly coloured than the basal T2 colour. Wings similar to females, transparent or faintly yellowish, apical spot dark brown (or brown in specimens with golden pubescence; see the section on R. tomentosa GERSTAECKER ). Antenna black dorsally, including scape and pedicel; terminal flagellomere sometimes with a faintly less dark or even brownish tip, but of much lesser extent than in R. fita sp. nov. ( Figure 68b View FIGURE 68 ). Eye setae missing or very short ( Figure 68a View FIGURE 68 ).

Head. Clypeus longer than wide, with parallel or almost parallel sides, no OCA, barely curved upes, almost linear apical margins and barely projecting, subacute apex ( Figure 68b View FIGURE 68 ). Basal half or two thirds largely and sparsely punctate, apical half or third with less defined puncture margins. Frons, gena and tempora coarsely punctate, mandibles with several conspicuously defined punctures basaly. Gena about 0.6–0.8 times as wide as eye. Entire clypeus covered by silvery pubescence of same length basally and apically; pubescence of frons longer, with characteristic setae that have basal three quarters straight and bent tips. Ocelli equidistant. AF1 longer than scape, AF2 1.7–2.1 times as long as wide. Tyloids on AF1 thin, occupying increasingly more surface towards tip, but remain thin until last three flagellomeres. Terminal few tyloids are sometimes barely elevated above the segment surface, rare feature in non- capensis -group, shared only with R. fita sp. nov. Terminal flagellomere elongated, with greater curvature radius on the outer margin, tip obtuse ( Figure 68b View FIGURE 68 ).

Mesosoma. Overall more coarsely punctate, with longer setae, especially on scutellum and metanotum. Coxa pairs II and III coarsely punctate. Tarsal I spur not developed.

Metasoma. Terminal sternum flattened or weakly concave.

Male-female pairing strength: high; confirmed by the mt DNA.

Variability. This species is showing some interesting patterns of colour variation. The first is the tendency to have a transversal black band on clypeus females, which is only seen in R. amanhii sp. nov., with three layers of colour. In addition to the colour pattern variability, this species also exhibits a pattern of pubescence differences across the entire distribution areal. Specimens from Eastern Africa often have golden pubescence ( Figure 106a View FIGURE 106 ), while those from Western Africa have predominantly silvery pubescence ( Figure 106b View FIGURE 106 ).

Similar species. The most similar species to this one is R. fita sp. nov. These are usually sufficient for determination, but there may be dubious specimens from the overlapping distribution regions ( Zambia, Zimbabwe, possibly also Tanzania). Problems are also possible in the separation of females from R. baki sp. nov. in Western Africa, which has shorter and evenly curved setae on frons and mesonotum in females, while males have different clypeus punctures (a yellow spot on mandibles provides additional support towards R. baki sp. nov.; specimens of R. tomentosa from Western Africa do not have any yellow markings on the mandible). Specimens of R. tomentosa (GERSTAECKER) from South Africa can sometimes resemble R. fita sp. nov. by having scape and pedicel dorsally reddish (as opposed to black in specimens from other regions of Africa); due to non-overlapping distribution range, such specimens can easily be assigned to R. tomentosa (GERSTAECKER) . Interestingly, Bequaert considers this species as a probable synonym of R. aethiopica (DU BUYSSON) ( Bequaret, 1918) , but none of the examined specimens seems to resemble this species, except possibly in the black colour of the tarsi.

Distribution. Entire Sub-Saharan Africa—this species was recorded from 19 countries, with the second-largest distribution areal. Most specimens originated from South Africa (20%), Kenya (15%), Zambia (12%), Tanzania (11%), Mozambique (9%), Zimbabwe (6%), Malawi (6%) and DR Congo (5%). The remaining specimens were recorded from Senegal, Sudan, Uganda, Central African Republic, Gambia, Gabon, Benin, Angola, Nigeria and Cote d’Ivoire. Such a wide distribution area suggests that this species probably occupies a separate niche not shared by other Ropalidia species. Notably, this species is relatively uncommon, accounting for only 3% of all examined specimens.

Nest. Several nests were examined, and all seem to fit a general pattern. The nest is discoid in shape, small, with smaller colony sizes of 5– 15 adult wasps; even large nests seem to have fewer adults (iNat:36558374). Nest dimensions are usually 15*30 cells, and the nest walls have uneven apical margins so that the cells usually appear as if they were somehow torn. The cell wall is lightly greyish, with occasional orange, dark grey or brown streaks. The opercula are the same colour as the cell wall; some opercula can have orange or lightly yellow nodules. Opercula are always at the very top of the cell, without remaining free wall. One iNat observation shows that the nest is located in an artificial structure on wooden planks (iNat:21104423), while nests can also appear on plants.

Genetics. Despite nearly entirely (Sub-Saharan) African distribution, only four separate BIN clusters were recorded; one originated from Nigeria (BOLD:AEA6088), one was recorded from Zambia (BOLD:ACH4326), while the last two were present in Tanzania and Kenya (BOLD:ADN8570, BOLD:ADO6841). The phylogenetic position of this species was initially somewhat confusing, with a basal position and some similarity to morphologically separate species like R. africana (CAMERON) stat. rev. However, the inclusion of Asian and Australian species in the phylogenetic analysis suggested that this species might be more closely related to Asian Ropalidia species. This finding might suggest a separate wave of the spread of the genus Ropalidia to Africa. Unfortunately, 28s rDNA was less informative.