Ropalidia jemmae Polasek & de Beer, 2023

Polasek, Ozren & de Beer, Len, 2023, A new species of social wasp from Madagascar with an inverted nest architecture (Hymenoptera, Vespidae), Journal of Hymenoptera Research 96, pp. 1031-1044 : 1031

Ropalidia jemmae Polasek & de Beer sp. nov.

Figs 1-5 , holotype labels Fig. 6

Material.

Holotype: “Ankafobe/Ambohitantely”, 1♀ . Paratypes: the same location as the holotype, 2♀♀. The nest from the same series also has an additional label "5. 52/(RP)", [nest A] (all in MSNV) .

Observation data.

Ankafobe [-18.10492, 47.187227], 27 Oct 2022 and 10 Nov 2022, 2♀♀ and a nest [nest B], obs. Len de Beer [https://www.inaturalist.org/observations/141686572, https://www.inaturalist.org/observations/140282514].

Diagnosis.

This species is characterized by the combination of the following characters: T1 shape streamlined, propodeal excavation impunctate, black basal colour and variably expressed whitish-green markings on the head and mesosoma, green markings only on coxa II, widened posterior yellow-green bands on T1 and T2, and overall longer pilosity. Wing length: 7.9 [7.8-8.0] mm.

Description.

Female. Colour. Basal body colour black (Figs 1 , 2 ). Head black, with green line in apical fourth of clypeus (Fig. 3 ). Interantennal area and inner orbits with faint green markings, mandible with basal green spot (Fig. 3 ). Gena and tempora suffused brown-green (Fig. 1 ). Antennal scape, pedicel and AF1 green ventrally, flagellum dorsally black, remaining flagellomeres ventrally orange (Fig. 1 ). Pronotum suffused green, with stronger green hue close to carina; inferior angle darker; mesonotum without green markings (Fig. 2 ). Suffused green spot high on mesopleuron, posterior third of tegula green (Figs 1 , 2 ). Scutellum with two green spots; metanotum with two green spots that have stronger margins than those on scutellum (Fig. 4 ). Propodeum black (Fig. 4 ). Coxa I and III black, coxa II with lateral green quadrant (very faint in one specimen). Femora black with elongated or circular green spot near distal margin on femora II and III. Tibia with two shades of green; tarsi green, distally light brown (Figs 1 , 2 ). Wings translucent, with some yellowing anteriorly; nervature yellow to brown, stigma yellowish and translucent, apical spot faintly developed in anterior third of marginal cell (Fig. 1 ). T1 with posterior yellow band that occupies about half of the total surface, thin connecting green suffused area and a dorsal remaining black diamond-shaped area (one paratype has mainly black T1, with thin remaining green band). T2 with posterior widened band, characterized by two larger attached areas and two remaining spots in basal colour near posterior margin, located close to T2/S2 suture (Fig. 1 ; band substantially reduced in one paratype, shown in Fig. 5 ). This pattern extends on S2 as short and smaller yellow-green spot, integrated with posterior band (very reduced in one specimen). Remaining terga and sterna in basal colour or somewhat brownish.

Head. Head frontally 1.2 × as wide as high; clypeus 1.15 × as wide as long (Fig. 3 ). Clypeal base elongated, lateral margins parallel, juxtamandibular lobe moderately developed, apex pointy and projecting (Fig. 3 ). Clypeus surface with basal sculpture and evenly spaced and well-defined small punctures, obscured by pubescence; punctures on apex coarser and converting into poorly defined craters (Fig. 3 ). Frons with dense, moderately sized and comparatively shallow punctures, vertex behind ocelli with diminishing punctures, area close to occipital carina impunctate and shiny. Gena and tempora with equally sized, but shallower punctures. Gena posteriorly 0.6-0.8 × as wide as eye, mainly parallel to posterior eye margin; occipital carina complete, reaches mandible. Clypeus and frons covered by dense and straight silvery-yellowish pubescence and yellowish protruding setae, about equally long as forward ocellus diameter (Fig. 3 ). Compound eyes setose (Fig. 3 ). Ocellar triangle equidistant; distance between lateral ocelli about 0.6 × of ocelli-eye distance. Scape equally long as AF1, AF1 equally long as AF2+3+4, AF2 about 1.4-1.5 × as long as wide.

Mesosoma. Mesosoma about 1.8 × as long as wide in dorsal view, mesonotum 1.2 × as long as wide (Fig. 2 ). Head wider than pronotal carina width (Fig. 2 ). Pronotal carina developed as translucent rim, twice wider dorsally than laterally; entire pronotum covered by shallow and very dense punctures separated from each other by their diameter; inferior pronotal corner with increasingly larger punctures (Fig. 1 ). Mesonotum punctures less dense and shallow, somewhat denser close to scutellum. Mesopleuron densely punctate. Metapleuron shiny, with an occasional very weak punctum that can only be visualized in specimen rotation. Scutellum densely punctate, with shallower punctures than those on mesonotum. Median scutellar carina developed and thin, reaches about half of scutellar length. Metanotum dorsally punctate, with shiny impunctate posterior triangle with small projecting area towards propodeum. Propodeal excavation shallow, without strong carina; upper half with cuticular surface, lower with minute striae; entire propodeal excavation completely impunctate (Fig. 4 ). Entire mesosoma covered by silvery-yellowish pubescence and some protruding setae; setae on dorsal side of pronotum silvery, those on mesonotum yellowish. Propodeal excavation covered by longer silvery setae.

Metasoma. T1 pyriform and elongated, with developed dorsal part, but not globular in shape; posterior sulcus very weak (Figs 1 , 2 ). T1 shallowly punctate, punctures poorly defined. T2 shiny, with shallow, dense and small punctures, covered by silvery pubescence and longer silvery-yellowish protruding setae that extend well over lamella (Fig. 5 ). T2 somewhat shorter than S2, visible in dorsally oblique lamella (Fig. 4 ). Remaining metasomal segments with weakly developed punctures and pubescence longer than that on T2 and S2.

Males are unknown (two more pre-hatching larvae were recovered from the cocoons of nest A, macerated and examined, but both were females). Notably, at least one male was observed on nest B (Fig. 8 ), with entirely yellow clypeus. However, in the absence of the specimen, the male remains undescribed.

Similar species.

Several Malagasy species have a similar morphology and a general colour pattern. In order to provide sufficient support to separating R. jemmae sp. nov. from previously described species, a partial key is provided here. The key is designed to separate the four similar species from others (key couplet 1). The key couplet 2 can be treated as 25b in the previous key to Malagasy species ( Giordani Soika 1991).

Nest.

The nest is the single most interesting feature of this species, with unique architecture in the entire genus Ropalidia . Instead of the cell openings oriented outwardly, the nests of R. jemmae sp. nov. are inverted, with the cell openings oriented towards the nesting surface and the cell bottoms oriented outwardly (Fig. 7 ). The loosely built cell bottoms thus correspond to the rugged texture of the tree bark or the lichen and provide excellent concealment of the nest (Fig. 8 ). In addition, the nest is built with greenish-grey material, mostly homogenous, without streaks of different colours integrated into the cell walls, which are common in some other species.

The first examined nest, nest A, has a total of 43 cells, arranged in the 7*9 cells maximum. The nest is somewhat elongated, with six enclosed cells (Fig. 9 ). The paper structure is brittle, visible in several collapsed cells (Fig. 9 ). Approximately 50%-75% of the cell length overlap between the cell rows (Fig. 10 ). The stalk of the same nest is also inverted, suggesting attachment on the cell openings side (Fig. 10 ). The outer (bottom-exposed) side of the cells has a very textured surface with numerous arches, which do not reflect the cell wall structure but are located much more densely, providing a heavily textured outer surface (Fig. 11 ). The greater magnification shows no elongated fibres, but only clumps of heavily masticated and mostly rounded chips (Fig. 12 ).

The second, nest B, was only observed in situ (Figs 7 , 8 ). The nest was on the tree trunk, 1.3 m above the ground. The nest colour and shape resemble the nearby greyish-green lichen patch (Fig. 7 ).

In comparison, the nests of R. ranavali are elongated with a pointy tip, suspended from similarly coloured branches (https://www.inaturalist.org/observations/63188743, https://www.inaturalist.org/observations/9173358). The nests of R. venustula and R. scottiana are unknown.

Etymology.

The name is given after Jemma de Beer, who participated in the nest B discovery.

Distribution.

All the examined specimens and observations originated from a narrow area (of no more than 16 km of distance) in central Madagascar near Ankafobe, at the edge of the Ambohitantely forest.

Figures

Figures 1 - 6. R. jemmae sp. nov., female, habitus 1 lateral view 2 dorsal view 3 head in frontal view 4 propodeal excavation 5 distal margin of T 2 6 label of the holotype.

Figures 7 - 12. R. jemmae sp. nov. nest 7 nest B, in situ, lateral view 8 with wasps 9 nest A, cell openings 10 lateral view 11 outer view (notably, the spot in the middle is the glue that connected the nest to the underlying cardboard) 12 greater magnification, showing a brittle paper structure.