Cionus Clairville

Caldara, Roberto & Košťál, Michael, 2023, A Taxonomic Revision Of The Afrotropical Species Of The Weevil Genus Cionus (Coleoptera: Curculionidae), Zootaxa 5288 (1), pp. 1-98 : 7-10

Cionus Clairville

Cionus Clairville, 1798: 66 [type species: Curculio blattariae Fabricius, 1792 (= Curculio alauda Herbst, 1784 )]. Germar, 1821: 299. Schoenherr, 1838: 722; 1845: 178. Reitter, 1904: 49; 1913: 84; 1916: 232. Wingelmüller, 1914: 187; 1921: 102; 1937: 143. Hustache, 1932b: 336. Hoffmann, 1958: 1211. Alonso-Zarazaga & Lyal, 1999: 76. Caldara & Korotyaev, 2002: 184. Caldara et al., 2014: 604. Košťál & Caldara, 2019: 7 . Alonso-Zarazaga et al., 2023: 185.

Mononyx Brullé, 1839: 72 [homonymy, non Laporte. 1832] (type species Mononyx variegatus Brullé, 1839 ). Uyttenboogaart, 1937: 115. Alonso-Zarazaga & Lyal, 1999: 76. Košťál & Caldara, 2019: 7.

Synonyms. Mononyx was described by Brullé (1839) based on a genus type species M. variegatus described in the same publication. This generic name is a junior synonym of Cionus Clairville and primary homonym of Mononyx Laporte, 1832 (Hemiptera) as noticed for the first time by Uyttenboogaart (1937).

Redescription. Body: subparallel to round, 3.0 mm to almost 6.0 mm in size. Head: rostrum slender to moderately stout, short to moderately long, but always less than double pronotum length, in females usually longer. Head between eyes generally distinctly narrower than rostrum width at base. Eyes large, moderately to broadly rounded. Antennae slender; scape longer than funicle; funicle 5-segmented with S2 as long as or longer than S1; club shortly suboval or spindle-shaped to elongated. Pronotum: always wider than long, punctured, evenly to unevenly, variously densely covered with elongated scales; with or without shallow to medium deep constriction before anterior margin, often in Afrotropical species with two or four small protuberances emphasized by tufts of erect scales. Prosternum: with variously deep emargination on anterior margin, without canal, at most with shallow concavity reaching coxae. Scutellar shield: triangular, flat, punctured to rugulose. Elytra: shortly rectangular to broadly rounded, with (most Palaearctic species and one Afrotropical and one Oriental species) or without dorsal and preapical black tomentous maculae, covered with variously arranged, elongated to hair-like fine scales, in some species with raised seta-like scales. Venter: mesosternal process flat to slightly convex, subquadrate to subtriangular, medial part of metasternum in males flat to concave. V1 and V 2 in males with indistinct to markedly deep and broad impression, in females flat to convex. V1–2 combined strikingly longer than V3–4 combined; V 2 in males of Afrotropical species often with a tuft of hair-like scales. Legs: profemora with indistinct to well-marked teeth, meso- and metafemora with large, mostly triangular sharp teeth. Tibiae straight to slightly inwardly curved, in both sexes without mucro (only males of the Eastern Palaearctic C. helleri and the Central African C. congoanus with mucro). T3 wider than T2, bilobed, protarsal onychia in some species in males strikingly elongated, claws at least at base connate, in males in most species, in females rarely of unequal length. Genitalia: Penis with body elongated, variously shaped, often with distinct flagellum, parameroid lobes absent, with more or less long apodemes, tegmen and tegminal apodeme well-developed. Spiculum gastrale (sternite IX) uniform, thin, at proximal end moderately to strongly enlarged, at distal end with well discernible, weakly sclerotized sternites VIII. Spermatheca relatively uniform, its corpus stoutly spherical, considerably sclerotized, cornu bent along corpus, in some species with visible ramus. Spiculum ventrale (sternite VIII) with long thin apodeme, at proximal end not or weakly enlarged, at distal end with large, moderately sclerotized plates forming irregularly bilobed structure, without fenestra. Gonocoxites almost indiscernible, not sclerotized, without styli.

Diagnosis. Anterior margin of prosternum with a more or less sharply incised emargination. Head between eyes not broader than rostrum at base. Elytra in many Palaearctic species characterized by one dorsal and one preapical black tomentous perisutural macula, which may be absent in some Palaearctic species, and is never present in all Afrotropical (except C. coniungens ) and Oriental (except C. albosparsus Faust, 1898 ) species. V1 always longer than V2–5, V1+2 always remarkably (approximately 2.5× to 7.0×) longer than V3+4. Most species with unequally long claws in males, less frequently also in females, especially on protarsi. Male genitalia always without parameroid lobes; spermatheca with robust body and long thin cornu. Sexual dimorphism not striking, unequally long claws much more often present in males, rostrum in males shorter with antennal insertion closer to apex, metasternum and ventrites 1–2 in median part concave in males, convex in females.

Comparative notes. The genus Cionus belongs to the tribe Cionini . The genus was recently redescribed in details by Caldara & Korotyaev (2002) and Košťál & Caldara (2019). According to these authors, the tribe is characterized by the following relevant synapomorphies: “head between eyes narrower posteriorly than anteriorly”, “S2 as long as or slightly longer than S1”, “median process of mesoventrite at least half as wide as a coxa”, “mucro on all tibiae absent in females” and “V1+2 much longer (at least 2.6×) than V3+4”. The tribe contains seven genera distributed worldwide except for the Americas and Australia ( Alonso-Zarazaga & Lyal, 1999). The genus Cionus can be recognized from the other genera of Cionini by one very distinctive character, a more or less sharply incised emargination on the anterior margin of prosternum. Additionally, unlike other genera of Cionini , most species of Cionus have unequally long claws in males, especially on the protarsi. Moreover, the genus Cionus differs from the following Palaearctic genera by: two claws vs. Stereonychus Suffrian, 1854 and Stereonychidius Morimoto, 1962 having only one claw; more or less convex body outline in lateral view vs. Cleopus Dejean, 1821 having body moderately flat; prominent humeri vs. Nanomicrophyes Pic, 1908 having indistinct humeri; lack of a prosternal canal vs. the likely most related genus Cionellus Reitter, 1904 having deep prosternal canal.

Biological notes. According to the current classification in APG IV (2016), the host plants of most species belong to the families Scrophulariaceae — Scrophularieae , (mainly Verbascum and Scrophularia ) for the Palaearctic species, and Buddlejeae ( Buddleja ) for the Afrotropical species —, Bignoniaceae (a few Oriental and Afrotropical species) and Paulowniaceae (one eastern Palaearctic species). All host families belong to Lamiales .

There are no published data on the biology of the Afrotropical Cionus . The new information that we bring here concerns exclusively the host plants. Therefore, data reported below concern Palaearctic species. The larvae of Cionini − for a detailed morphological description see the recent paper by Jiang et al. (2020) − are ectophagous, living externally on their host plants or hidden between adjoining leaves and feeding on flowers and leaves. Though legless as in other weevils, they move nimbly on plant surfaces being covered with viscid mucus, which is secreted by a retractile tubular organ on the last abdominal segment. When mature, the larvae secrete a substance containing chitinous microfibres from their midgut ( Tristram 1978), using which they construct a spherical translucent cocoon generally on the underside of leaves or branches, exceptionally also inside flower calyces for pupation ( Read, 1977).

Distribution. Palaearctic, Afrotropical (including Madagascar) and Oriental regions.

List of Afrotropical species and their synonyms

Continental species

1. Cionus congoanus Hustache, 1932a

2. Cionus coniungens sp. n.

3. Cionus pericarti Hoffmann, 1968

4. Cionus frater sp. n.

5. Cionus perlatus Faust, 1885

6. Cionus vicarius Hustache, 1939

7. Cionus tristis Boheman, 1838

8. Cionus albidus Rosenschoeld, 1838

9. Cionus schuelei sp. n.

10. Cionus transvaalicus sp. n.

11. Cionus mimeticus sp. n.

12. Cionus intermedius sp. n.

13. Cionus cretaceus sp. n.

14. Cionus fimbriatus sp. n.

15. Cionus diaboli sp. n.

16. Cionus meticulosus ( Sparrman, 1785)

17. Cionus angulicollis Rosenschoeld, 1838

= Cionus chilianthi Marshall, 1941: 28 . (syn. n.)

18. Cionus tenuepilosus sp. n.

19. Cionus pardus Marshall, 1941

20. Cionus oculatus sp. n.

21. Cionus notatus Rosenschoeld, 1838

22. Cionus pustulatus Fåhraeus, 1871

23. Cionus nubilosus Rosenschoeld, 1838

= Cionus virgatus Rosenschoeld, 1838 (syn. n.)

= Cionus decorus Boheman, 1845 (syn. n.)

24. Cionus histrio Rosenschoeld, 1838

25. Cionus latruncularius sp. n.

26. Cionus limosus sp. n.

27. Cionus terrosus sp. n.

28. Cionus usambicus Faust, 1889

29. Cionus tanzanicus sp. n.

30. Cionus hirtellus sp. n.

31. Cionus concavifrons sp. n.

32. Cionus longinasus sp. n.

33. Cionus ingratus Fåhraeus, 1871

34. Cionus friedmani sp. n.

35. Cionus geometricus sp. n.

36. Cionus zimbabwicus sp. n.

37. Cionus stalsi sp. n.

38. Cionus natalensis sp. n.

39. Cionus nhlosanicus sp. n.

40. Cionus oberprieleri sp. n.

Madagascan species

41. Cionus alluaudi Hustache, 1920

42. Cionus leucostictus Fairmaire, 1897

= Cionus leucostictus griseus Fairmaire, 1903 (syn. n.)

43. Cionus compactus Fairmaire, 1903

44. Cionus convexiusculus sp. n.

45. Cionus planus sp. n.

46. Cionus guttula sp. n.

47. Cionus ebeninus Hustache, 1956

48. Cionus callosus sp. n.

49. Cionus catenatus Fairmaire, 1897

50. Cionus coriaceus Fairmaire, 1903

51. Cionus verrucosus sp. n.

52. Cionus variolosus sp. n.