Derelomus Schoenherr 1825

Genus Derelomus Schoenherr, 1825 Derelomus signatus group Species in this group exhibit a more or less dense cover of white scales on the lateral carina of pronotum (Fig. 1C). Their body is slender, the pronotum at most slightly wider than long (W: L ratio generally <1.30). The body of the penis is generally comparatively very long and apodemes very short (but see D. caldarai sp. nov. and D. karooensis sp. nov.). Eight species are recognized in this group, they are predominantly distributed in eastern and southern Africa, but one species extends to the Arabian Peninsula (D. schoedli) and one is found in North Cameroon, Cape Verde archipelago, Burkina Faso and Senegal (D. lindbergi). All species were collected on inflorescences of Mimosa L. and Vachellia Wight & Arn. (Fabaceae), which probably constitutes the host for larvae. This species group is likely more diverse than what is reported below. Several unique female specimens clearly belonging to new species were found in collections, but not described due to the lack of male or DNA grade material. Derelomus pallidus group This species group contains only three species, which exhibit a uniformly pale brown integument, a comparatively small body size, equal to or below 2.5 mm, and a lateral carina on the pronotum lacking a dense cover of white scales. The monophyly of this species group is supported by molecular data, at least for the two species D. pallidus and D. prochesi sp. nov. (Fig. 33). Species in this group are restricted to East and southern Africa, they are associated with Ebenaceae and Achariaceae. Derelomus nigrovariegatus group This species group is defined by the combination of a glabrous lateral carina on the pronotum, the comparatively large body length (generally beyond 3 mm) and the prosternum at least partly dark brown. The protibiae of the males exhibit a distinct internal comb of erect setae and the sex dimorphism for the shape and curvature of the rostrum is marked (note that these features have not been verified in D. nigrovariegatus Hustache, 1936 due to the unavailability of males). Six species are recognized in this group, they are distributed in Central, East and southern Africa. Most species were collected on male inflorescences and in fruits of Phoenix reclinata Jacq. (Arecaceae) and one species develops in flowers of Strelitzia nicolai Regel & Körn. (Strelitziaceae). Derelomus ephippiger group This is the largest and possibly a non-monophyletic species group in Derelomus. Stable and simple synapomorphies to define it were not identified in the context of this study. The following combination of features should enable to distinguish this clade from the rest of the genus: lateral carina on pronotum glabrous, claw simple, prosternum uniformly pale brown (except in dark specimens of D. chamaeropis), head concolorous or slightly darker than pronotum and stridulatory plate with compact lines of granules, space between granules as wide or narrower than diameter of a granule. Species in this group are generally either longer than 2.5 mm, with dark patterns on the elytra or with costate elytra and never lack these three features combined. The majority of species also exhibits the following features: presence of a post-ocular dark strip, lateral carina on pronotum with distinct notch or tooth near middle of length, pronotum distinctly transverse (W: L ratio at least 1.36) and elytra in males very wide, lens or pearshaped with 5 th interstriae raised (see D. piriformis). This group is widely distributed in the study area and includes twelve species associated with male inflorescences of various palms (Chamaerops L., Cocos L., Phoenix L.; Arecaceae). Many species are found in sympatry, apparently sharing the same host and tissue. Several species concepts show geographic variants possibly corresponding to distinct species that would deserve more investigation. Key to species of Derelomus Schoenherr, 1825 1. Lateral carina of pronotum glabrous or with minute setae not concealing the integument (Fig. 1B). Forehead glabrous or with scattered setae (Fig. 1B). Rostrum variable in size, as long as or distinctly longer than pronotum in lateral view in males ................................................................................. 9 – Lateral carina of pronotum concealed with whitish scales, or with a band of scales contrasting with the vestiture of the rest of pronotum (Fig. 1C). Forehead generally with two tufts of white scales near eyes (Fig. 2A). Rostrum comparatively short, generally as long as or slightly longer than pronotum in males in lateral view. On Fabaceae ............................................................................................... 2 2. Elytra with two transverse stripes or lines of dark spots on each elytron (Figs 2A, 3A, 4A) .......... 3 – Elytra with one or no transverse band or line of dark spots on each elytron (Figs 5A, 8A). Some rare specimens of D. abyssinicus exhibit two bands on elytra, in that case the rostrum is almost straight in lateral view in both sexes (Fig. 4B–C) ......................................................................................... 5 3. Pronotum with white scales on dorsum (Fig. 2A). Claws appendiculate internally (Fig. 1F). On Vachellia spp. ......................................................................................... D. signatus Gyllenhal, 1836 – Pronotum with minute whitish setae, glabrous in appearance (Figs 3A, 4A). Claws simple (Fig. 1F) ............................................................................................................................................ 4 4. Rostrum as long as pronotum in lateral view (Fig. 3B–C). Pronotum distinctly transverse (W:L ratio: 1.33). Apex of elytra jointly rounded. Body of penis moderately elongate (W: L ratio: 0.37, Fig. 3D); apodemes long, 0.8 × as long as body of penis. On Vachellia karroo .. D. karooensis Haran sp. nov. – Rostrum slightly longer than pronotum in lateral view (Fig. 4B–C). Pronotum isodiametric (W: L ratio: 1). Apex of elytra acuminate. Body of penis elongate (W: L ratio: 0.13); apodemes very short (Fig. 4D). On Vachellia xanthophloea ................................................ D. acuminatus Haran sp. nov. 5. Rostrum regularly and moderately downcurved in lateral view (Fig. 5B–C). Claws simple (Fig. 1F). On Vachellia spp. ............................................................................... D. abyssinicus Hustache, 1936 – Rostrum in lateral view distinctly downcurved, more so near base (Figs 6B–C, 7B–C, 8B–C). Claws appendiculate (Fig. 1F) ..................................................................................................................... 6 6. Apex of body of penis rounded, not forming a long spatula (Figs 6D, 7D). Median area of stridulatory plate rounded at apex, with series of 4 granules (Figs 6E, 7E) ........................................................ 7 – Apex of body of penis expanded, forming a long spatula (Figs 8D, 9D). Median area of stridulatory plate more acute at apex, with series of 5–6 granules (Figs 6E, 7E)................................................. 8 7. Elytra with a transverse dark line, sometimes reduced to a series of dots on even interstriae (Fig. 6A– C). Pronotum darker along medial line. Club darker than funicle in male (Fig. 6A). Southern and Eastern Africa ........................................................................................... D. caldarai Haran sp. nov. – Body integument uniformly pale brown, some individuals with a dark spot beyond middle of length of interstriae 4 of elytra (Fig. 7A). Pronotum uniformly pale brown. Club and funicle concolorous (Fig. 7A). Cape Verde Archipelago, Cameroon and Senegal. On Vachellia ........................................ ................................................................................................................. D. lindbergi Roudier, 1957 8. Body integument uniformly pale brown, elytra in some specimens with a dark spot beyond middle of length of interstriae 4 (Fig. 8A). Apex of penis body forming a spatula 2 × as long as wide, moderately bisinuate in lateral view (Fig. 8D). On Vachellia nilotica ............................................... ............................................................................................................... D. pericarti Hoffmann, 1968 – Body integument pale brown, elytra with a line of dark spots beyond middle of length of interstriae 2, 4, 6 (Fig. 9A). Apex of penis body forming a spatula 4 × as long as wide, bisinuate in lateral view (Fig. 9D). On Vachellia ...................................................................... D. schoedli Rheinheimer, 2005 9. Body integument uniformly pale brown (Figs 10A, 11A). Smaller species, body length equal or below 2.5 mm. Males with smooth elytra. On Ebenaceae and Achariaceae .................................. 10 – Body with dark pattern on dorsum or with body length larger than 2.5 mm. In some species males with costate elytra (Fig. 25A). On Arecaceae, Anacardiaceae & Strelitziaceae ............................. 12 10. Rostrum elongate, at least 5× as long as wide in dorsal view, distinctly longer than pronotum in lateral view (Fig. 11C–D). Metanepisterna with a dense vestiture of white scales (Fig. 11F). Claws appendiculate (Fig. 1F). Line of granules on stridulatory plate with spaces larger than width of a granule (Fig. 11D, H). On Achariaceae ...........................................................................................11 – Rostrum short, at most 4 × as long as wide in dorsal view, as long as pronotum in lateral view (Fig. 10B). Metanepisterna with few non-overlapping white scales (Fig. 10B). Claws simple (Fig. 1F). Line of granules on stridulatory plate with spaces as wide as or narrower than width of a granule (Fig. 10E). On Ebenaceae ........................................................................ D. pallidus Fåhraeus, 1844 11. In