Ebenacobius Haran & Benoit & Procheş & Kergoat 2022, gen. nov.
Creators: name: Haran, Julien
name: Benoit, Laure
name: Procheş, Şerban
name: Kergoat, Gael J.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Curculionidae
Ebenacobius

description: Genus Ebenacobius Haran gen. nov.
urn:lsid:zoobank.org:act: D2186F53-765F-47DA-9971-29B955BCF7A8
Type species
Ebenacobius rhodesianus (Hesse, 1929) gen. et comb. nov., by present designation.
Differential diagnosis
This genus agrees in all respects with the features enabling Afrotropical Derelomini to be distinguished from other Curculioninae: prothorax with a lateral carina, interstriae 9 on elytra raised and males with tergite VII forming a stridulatory plate with two rows of tubercles (Fig. 1J). Ebenacobius gen. nov. can be distinguished from other Derelomini genera by the following combination of putative synapomorphies: protibiae armed with an apical mucro (Fig. 1F); claws free; eyes convex, exceeding the contour of head in dorsal view (Fig. 1A–B); forehead with a median furrow (Fig. 1B); prothorax only constricted laterally near apex (Fig. 1A), not strangled (as in Derelomus Fig. 1C). Additional diagnostic features enabling to distinguish species of Ebenacobius from the closely related genus Derelomus Schoenherr, 1825 include the stridulatory plate (tergite VII) in males with basal margin lacking indentation on each side of the row of tubercles (Fig. 1J), and the base of the body of penis in lateral view lacking a thickening (Fig. 1I). The larval development of some species of Ebenacobius takes place in flowers of dicot plants, which contrasts with the life history of the large majority of species of Derelomini, themselves largely monocot-associated.
Etymology
The genus name refers to the association of species of this genus with inflorescences of Euclea spp. from the family Ebenaceae. The gender is masculine.
Description
Male
BODY LENGTH. 2.1–4.0 mm.
COLOUR. Body integument pale brown to reddish brown, generally with dark brown patterns on prothorax (colour uniform in 10% of species); dorsum (prothorax + elytra) with a coating made of minute recumbent setae or whitish scales or long erect setae.
MOUTHPARTS (Fig. 1H, N–O). Mandible with 2 teeth (Fig. 1N), outer dens slightly narrower and more arcuate than inner dens, outer margin with 1–2 punctures near basal third, bearing very short to long seta. Maxilla (Fig. 1H) with galea, lacinia and palpiger fused, outer margin with 2 elongate setae, inner apical ¾ with dense setation, middle of length with about 8 broad lacinial dentes; maxillary palp 3-segmented, located on apex of palpiger, glabrous; I 2× as wide as long, II moderately transverse, glabrous, III as long as wide, apically papillate. Labium (Fig. 1O) with prementum transverse, 2× as wide as long, laterally with 1 very long seta near middle of length; labial palp 3-segmented located on apical margin of prementum; I globular, larger than 2, with a large seta, II similar to I but about 2× smaller, III small, 2× smaller than II, globular, apically papillate.
ROSTRUM. Slightly shorter to 1.2× longer than prothorax in lateral view, almost straight (Fig. 4C) to strongly downcurved (Fig. 4E), curvature uniform or stronger in basal ⅓; underside with whitish setae between scrobes, short and recumbent to erect and almost as long as segment 1 of funicle, integument forming an angle or tubercle near mouthparts, sometimes absent; scrobes elongate, narrow, extending from antennal insertion to apical margin of eyes, upper margin carinate, entirely straight; in dorsal view rostrum about as wide as profemora, width similar overall, slightly widening near apex, bearing 5 carinae, the central one sometimes divided into two throughout, or basally and near antennal insertion, with small whitish setae oriented toward central carina, contiguous or not, area near mouthparts smooth and shiny, with very short setae oriented forward.
ANTENNA. Inserted at apical ¼ or 2/5 of length; scape as long as protibiae, narrow, straight, slightly clavate at apex, 2× wider there than in middle of length, contiguous or subcontiguous with anterior margin of eyes in repose; funicle 7-segmented, as long as ⅔ of length of scape, bearing short whitish setae, segment 1 longer than wide, 2 transverse to 2× as long as wide, 5–7 transverse; club 3-segmented, oval, compact, with dense, short pubescence, segment 1 longer than 2+3.
EYES. Moderately to strongly convex in dorsal view, exceeding the contour of head (Fig. 1B); in lateral view subcircular, contiguous with lower contour of head or closer to lower than upper contour of head.
HEAD CAPSULE. Globular, coarsely punctate dorsally, forehead with a deep median groove (Fig. 1B); in lateral view integument smooth or scarcely punctate, at least with a row of punctures surrounding posterior margin of eyes, each bearing a seta (Figs 4–5).
THORAX. Prothorax. Transverse in dorsal view (W:L ratio: 1.16–1.40) apical margin straight or slightly bisinuate, ⅔ to ¾ as wide as basal margin, basal margin slightly bisinuate; sides subparallel or moderately to strongly convex, widest near base or near middle of length, more or less abruptly converging apicad, generally forming an apical constriction (collar) at least as long as width of scape at apex. Mesepimeron and Mesepisternum triangular, the latter reaching anterior margin of metepisternum. Metepisternum extending beyond lateral margin of metasternum, with ventral margin concave. Prosternum at least 2× as long as than mesosternum, convex or forming a protruding prothoracic process between procoxae sometimes reduced to a small blunt tubercle; apical margin concave, basal margin straight; central area glabrous or with recumbent whitish scales, not overlapping; procoxal cavities inserted from middle of length to basal 1/6, not contiguous. Mesosternum 2 to 3 × as short as metasternum, transverse, convex, posteriorly projecting between mesocoxae and reaching middle of their length, posterior margin with metasternum straight; mesocoxal cavities separated by distance slightly shorter than their width. Metasternum more than 2 × as wide as long, convex laterally, medially canaliculate on posterior ⅓ of length, anterior margin projecting between mesocoxae, posterior margin projecting before middle of length of metacoxae, posterior margin slightly indented; metacoxal cavities 2 × as wide as long, separated by distance slightly shorter than their width.
LEGS. Prothoracic legs (Fig. 1F) slightly longer and wider than mesothoracic legs; procoxa large, subspherical; protrochanter longer than wide, basally rounded, acute at apex; profemora similar in length to prothorax length or slightly shorter, widest near middle of length, internally sinuate or angulate in apical ⅓; protibiae slightly shorter than profemora, in cross-section subcircular, width regular or expanding from base to apex, external margin straight or downcurved in apical ⅓, internal margin bisinuate; apex slightly broadened with an internal mucro (acute and downcurved) and an anteapical brush of setae contiguous with mucro (Fig. 1F), apical margin obliquely truncate with antero/posteroventral margin with row of 15–20 elongate, pale brown, acute spines, homologous to setae; protarsus 5-segmented, ⅔ as long as protibia; segment 1 longer than wide; 2 and 3 transverse, 3 deeply bilobate; 4 ⅓ as long as 2; 5 as long as 2 +3, widening apicad; protarsal claws free, simple or with a thickening or a tooth internally. Mesothoracic legs similar to prothoracic legs but shorter and slender, external margin of mesotibiae at least slightly arcuate outward in apical ½, with or without apical mucro. Metathoracic legs similar to mesothoracic legs, slightly longer, apical mucro shorter when present.
SCUTELLAR SHIELD. Exposed, small, rounded, slightly convex, glabrous.
ELYTRA. In dorsal view elongate (W:L ratio: 0.64–0.76), sides slightly convex, widest near middle of length (Fig. 1A), at humeral angles subquadrate, slightly wider than basal margin of prothorax; in lateral view convex, regular or more convex on declivity, lateral margin slightly bisinuate; 10-striate, striae at least slightly narrower than interstriae, 3–4 and 5–6 merging before apical margin, 9–10 merging or submerged in apical ⅓, 9 erased in basal 1/6 (distinct on Fig. 4J). Interstriae slightly to strongly convex, 9 more convex than 1–8 or carinate throughout. Vestiture (when visible) with 2–3 rows of scales or setae on each interstria, oriented posteriorly (Fig. 1D–E).
ABDOMEN. Venter nearly 3× as long as than metasternum, laterally convex. Ventrite 1 medially slightly longer than 2, posterior margin bilobate; 2 ⅔ as long as 3+4+5; 2–4 with apical margin straight; integument of ventrites densely punctate, each puncture bearing a whitish seta oriented posteriorly. Tergites 1–6 with a basal dark band, in 1 and sometimes 2 interrupted in middle. Tergum 7 (stridulatory plate) with basal margin obtuse in middle (Fig. 1J), straight laterally, apical margin bilobate, setose; medially with two subparallel rows of 6–10 tubercles.
TERMINALIA. Tergum 8 transverse, subrectangular, basal margin straight, apical margin and posterior angles broadly convex, surface punctate, setose. Sternum 8 forming 2 small transverse separated sclerites, outer margin acute, downcurved inward. Spiculum gastrale nearly as long as body of penis, basally downcurved, medially flattened in cross-section, apically asymmetrically widening into two obtuse projections, apical margin straight. Tegmen nearly as long as penis body, connected, forming a ring around penis body. Penis body (Fig. 6) in dorsal view moderately to very elongate (W:L ratio: 0.5–0.26), basal margin bisinuate or concave, latero-basal edges rounded, sides bisinuate or subrectate or convex, converging apicad in apical 1/6 or strangled before apex, apical margin acute or acuminate or rounded or truncate; in lateral view curvature stronger in basal ½. Apodemes 2 × shorter to 2 × longer than penis body.
Female
TERMINALIA. Tergum 8 ⅔× as long as sternum 8, transverse (W:L ratio: 2), apical margin regularly convex, setose, basal margin ill-sclerotized in middle, surface punctate, punctures condensed near apical margin. Tergum 9 similar in shape to tergum 8, 2× smaller. Sternum 8 (Fig. 1L) slender, apical ¼ Y-shaped, arcuate widest near middle of length, moderately sclerotized. Coxites (Fig. 1K) 2 × shorter than sternum 8, narrowed apicad, moderately sclerotized; styli 2 × longer than wide, apically with 4–5 erect setae. Spermatheca stocky or slender (Fig. 1M), cornu wide and curved, nodulus rounded, collum and ramus inserted near base, forming 2 projections, transverse or 2 × longer than wide, contiguous or distinctly separated.
Sexual dimorphism
Females can be distinguished from males by their rostrum which is slightly narrower, at least slightly longer and less downcurved in lateral view. Females lack a prosternal process between procoxae or a cuticular elevation before procoxae.
Variation
Intraspecific size variation is moderate in this genus. The background colour of integument and dark patterns on dorsum can be, however, quite variable within a population. Males may show a substantial variation in size and shape of prothorax and of prosternal process. In ‘minor’ males, this process may be reduced to a small blunt tubercle between the procoxae.
Remarks
As defined here, this genus contains 19 species, but at least four additional species (only represented by one or two female specimens) await description (deposited in CBGP, FFWS and MNHN). The inconspicuous nature of the species in this genus and the presence of cryptic or closely related sympatric species in this group indicate that more species may be discovered with more focused sampling. The genus Ebenacobius gen. nov. provides another example of presence of a prothoracic process in males among the Afrotropical Derelomini (Haran et al. 2020). Prothoracic structures of males such as prothoracic horns are usually used in fights between males (Davis & Engel 2010). In most Ebenacobius the role of these structures remains unclear since they are generally quite small or not protruding forward (Fig. 4G).
Life history
Most species seem to develop in flowers of Euclea (Ebenaceae) although some seem to be associated with flowers of other dicot plant families (Apocynaceae, Sapotaceae). The detailed life cycle is known for E. hessei Haran gen. et sp. nov. on Euclea natalensis A.DC. (see details under that species). Adults may form massive aggregations on inflorescences of their host. Some species are inconspicuous and have only been collected using a light trap or by sifting leaf litter. In several species, field observations indicate a timed crepuscular flight phenology. Adults are generally active from late winter to summer, though some species are found all year round.
Distribution
In the current state of knowledge, the genus Ebenacobius gen. nov. is distributed in southern and southeastern Africa, from the Western and Northern Cape Provinces of the Republic of South Africa to southern Malawi. The highest species diversity occurs in the north-east provinces of the Republic of South Africa, which is consistent with the distribution of representatives of the genus Euclea (Schmidt et al. 2002).
Key to species of Ebenacobius Haran gen. nov.
1. Claws simple ..................................................................................................................................... 2
– Claws appendiculate internally ....................................................................................................... 16
2. Prothorax and elytra with dorsum glabrous or with setae (Fig. 1D) ................................................ 3
– Dorsum with small whitish scales (Fig. 1A, D) .... E. rhodesianus (Hesse, 1929) gen. et comb. nov.
3. Body covered with long erect setae, as long as length of segment 1 of funicle; apex of elytra acute; apical ⅓ of protibiae downcurved with a long internal mucro at apex (Fig. 2A) ............................... ...................................................................................................... E. curvisetis Haran gen. et sp. nov.
– Body at most with recumbent setae, shorter than length of segment 1 of funicle; apex of elytra jointly rounded; protibiae straight, with a short internal mucro at apex ...................................................... 4
4. Rostrum short and almost straight in lateral view (Fig. 4C); in males, underside of rostrum smooth, lacking an angle or tubercle near mouthparts. Body integument generally uniformly pale brown (Fig. 2B), only 2% of specimens with dark dots near middle of length of interstriae 5 of elytra or forming a dark band between these dots. Males lacking a prosternal process near procoxae ............ ................................................................................................... E. rectirostris Haran gen. et sp. nov.
– Rostrum elongated and distinctly downcurved in lateral view (Fig. 4D–J); in males, underside of rostrum with integument forming an angle or tubercle near mouthparts. Body integument generally with dark patterns on elytra and/or prothorax, or uniformly reddish brown (Figs 2C–I, 3A–E). Males with or without prosternal process near procoxae ............................................................................ 5
5. Striae on elytra made of a double row on punctures (Fig. 2C). First segment of funicle elongate, 2.5 × as long as wide (Fig. 4E) ........................................................... E. duplicatus Haran gen. et sp. nov.
– Striae with a single row of punctures (Fig. 1D). First segment of funicle of funicle at most 2 × longer than wide ........................................................................................................................................... 6
6. Rostrum very elongate, in lateral view 1.2 × as long as prothorax (Fig. 4G). In males, prosternal process oriented backward .................................................... E. grobbelaarae Haran gen. et sp. nov.
– Rostrum shorter, generally as long as prothorax in lateral view (Fig. 4D), at most 1.1 × as long as prothorax (Fig. 4I). In males, prosternal process oriented forward (when present) ......................... 7
7. Basal ⅓ of striae 1 with punctures well aligned (Fig. 1D) ............................................................... 8
– Basal ⅓ of striae 1 with punctures slightly to strongly misaligned (Fig. 1E) ..................................... .................................................................................. E. costalis (Fåhraeus, 1844) gen. et comb. nov.
8. Dorsum (prothorax + elytra) with distinct dark pattern, forming longitudinal, transverse or oblique bands on elytra (Figs 2H–I, 3A–E); background colour of elytra generally pale yellow (only dark reddish in E. kuscheli gen. et sp. nov.; Fig. 2I) ............................................................................... 10
– Dorsum uniformly reddish brown, lacking dark pattern on prothorax or elytra (Fig. 2F–G) .......... 9
9. Eyes almost flat, moderately exceeding the lateral curve of head in dorsal view (Fig. 2F). In males prothorax almost forming a rectangle, not narrowed before apex near eyes. Body of penis short, 2 × as long as wide in dorsal view, strongly downcurved before middle of length in lateral view (Fig. 6F). Profemora in males smooth, lacking internal angle near middle of length ........................ .................................................................................................... E. thoracicus Haran gen. et sp. nov.
– Eyes convex, strongly exceeding the lateral curve of head in dorsal view (Fig. 2G). In males prothorax narrowed at apex near eyes. Body of penis elongate, more than 2 × as long as wide in dorsal view, moderately downcurved in lateral view (Fig. 6G). Profemora in males with an internal angle near middle of length ................................................................................ E. xhosa Haran gen. et sp. nov.
10. Second segment of funicle longer than wide. Prothorax densely punctate, space between larger punctures at most 2 × larger than diameter of punctures. Apodemes of penis as long as or longer than body of penis (Fig. 6K–N). Prothorax with dark bands or uniformly dark brown (Figs 2H–I, 3B–E) ...............................................................................................................................................11
– Second segment of funicle transverse. Prothorax with scattered puncturesseparated by a distance 2 to 3 × the diameter of punctures at least in some part of the central area. Apodemes of penis shorter than body of penis (Fig. 6J). Prothorax uniformly pale brown, similar to the background colour of elytra (Fig. 3A) ....................................................................... E. mulanjensis Haran gen. et sp. nov.
11. Prothorax with very short setae, shorter or as long as diameter of larger punctures, punctures not contiguous ....................................................................................................................................... 12
– Prothorax with long setae, longer than diameter of larger punctures, punctures subcontiguous at least laterally ......................................................................................... E. kuscheli Haran gen. et sp. nov.
12. Prothorax with longitudinal dark bands (Fig. 3B–E). In males rostrum moderately downcurved in lateral view (Fig. 5A, C, E, G) ........................................................................................................ 13
– Prothorax uniformly dark brown (Fig. 2H). In males rostrum strongly downcurved in lateral view, almost forming a quarter of a circle (Fig. 4F) ...................................... E. san Haran gen. et sp. nov.
13. Prothorax with 2 longitudinal dark stripes on each side of the median line (Fig. 3C–E) ............... 14
– Prothorax with 3 longitudinal dark bands, one median and two lateral (Fig. 3B) .............................. .......................................................................................................... E. hessei Haran gen. et sp. nov.
14. Scutellar shield and base of interstriae 1 pale brown, similar in colour to the rest of background colour of elytra; dark bands on prothorax not reaching apical margin (Fig. 3C–D) ...................... 15
– Scutellar shield and base of interstriae 1 dark brown; dark bands on prothorax generally reaching apical margin (Fig. 3E) ................................................... E. hippopotamorum Haran gen. et sp. nov.
15. Elytra glabrous in appearance, with very small setae, almost invisible. In males rostrum slightly shorter than prothorax in lateral view (Fig. 5C). Body of penis truncate at apex, sides widening from base to apex (Fig. 6L) .......................................................................... E. pedi Haran gen. et sp. nov.
– Dorsum of elytra with aligned recumbent and subcontiguous setae on interstriae 5–10. In males rostrum as long as prothorax in lateral view (Fig. 5E). Body of penis converging apically, acute at apex (Fig. 6M) ................................................................................. E. tsonga Haran gen. et sp. nov.
16. Dorsum with minute setae, glabrous in appearance (Fig. 3F). Body of penis longer than apodemes (Fig. 6O) .................................................................. E. incognitus (Hesse, 1929) gen. et comb. nov.
– Dorsum with distinct erect or recumbent setae (Fig. 3G–H). Body of penis shorter than apodemes (Fig. 6P–Q) ..................................................................................................................................... 17
17. Elytra with long erect and downcurved setae (Figs 3G, 5D). Apical margin of elytra yellow, similar to general background colour (Fig. 3G) .................................. E. oberprieleri Haran gen. et sp. nov.
– Elytra with recumbent setae (Figs 3H, 5F). Apical margin of elytra black or dark brown, contrasting with the pale brown colour of background of elytra (Fig. 3H) ....................................................... 18
18. Interstriae with a row of long, erect piliform setae (see remarks section under that species) ............ ................................................................................... E. turneri (Marshall, 1935) gen. et comb. nov.
– Interstriae with a row of short, not or slightly raised squamiform setae ............................................ ........................................................................................ E. atratus (Hesse, 1929) gen. et comb. nov.
description: Published as part of Haran, Julien, Benoit, Laure, Procheş, Şerban & Kergoat, Gael J., 2022, Ebenacobius Haran, a new southern African genus of flower weevils (Coleoptera: Curculioninae: Derelomini) associated with dicotyledonous plants, pp. 1-54 in European Journal of Taxonomy 818 (1) on pages 7-13, DOI: 10.5852/ejt.2022.818.1771, http://zenodo.org/record/6532969