Ctonoxylon flavescens Hagedorn, 1910

Jordal, Bjarte H., 2024, An integrated taxonomic revision of Ctonoxylon (Coleoptera, Curculionidae, Scolytinae) reveals new Malagasy species originating from multiple recent colonisations of the island, ZooKeys 1203, pp. 95-130 : 95-130

Ctonoxylon flavescens Hagedorn

Figs 21 , 24 , 27

Ctonoxylon flavescens Hagedorn, 1910: 4.

Ctonoxylon flavescens usambaricum Eggers, 1920: 38.

Ctonoxylon flavescens opacum Strohmeyer , nom. dub. – not published.

Type material.

Holotype: Kamerun [ ZMHB]; ‘ type’ of C. flavescens opacum : Kamerun [SDEI] . Holotype of C. flavescens usambaricum : Mkulumusiberg 1000 m, bei Sigi Ostafrika [ NHMW] .

Diagnosis.

Length 2.2–3.1 mm. 2.1–2.3 × as long as broad; colour brown, dull. Upper and lower eye parts separated by more than width of upper part; pronotal eye scraper acutely pointed; a sharp carina running from scraper to procoxa, without associated groove or propleural pit; scutellar shield at level with elytra; striae distinctly impressed; interstrial setae bristle-like, variable in length and placed irregularly in partly confused rows, without ground vestiture; elytral apex slightly emarginated; resting position of mesotibiae marked on metaventrite.

Distribution.

Guinea, Ghana, Cameroon, Democratic Republic of the Congo, Gabon, Uganda (new country record), Tanzania.

New records.

Uganda, Masindi, Budongo, Nyabyeya [GIS: 1.673, 31.540], 3. July. 1998, ex Ficus branch, B. Jordal, leg. [ ZMUB] ; Budongo, BFP Station, Sonso [1.723, 31.545], 6. 10. 2004, T. Wagner leg. [1, ZFMK] ; Kichwamba [0.71, 30.20], 25. 04. 1968, P. J. Spangler [1, USNM] ; Cameroon, Limbe, Ekande [GIS: 4.081, 9.172], 1000 m. alt., 20. Nov. 2007, ex Cola acuminata standing tree, B. Jordal, leg [ ZMUB] ; [ Ghana], ‘ Gold Coast’, Takoradi [4.90, - 1.75], 10. 12. 1946, ex bark of mahogany logs [ Khaya ivorensis ] [4, USNM] .

Biology.

Very little is known about this species despite frequent collections from many African countries. This study reports Cola as a new host plant genus in the same family Malvaceae as for the previously recorded Triplochiton (see Schedl 1961). Another new record from Ficus is in line with some other collections of closely related species taken from various Moraceae genera (see below). It is also reported here from African mahogany logs ( Meliaceae ), demonstrating a rather broad assembly of host plants. Records are generally from the bark of larger branches and trunks where the maternal egg tunnel is cut longitudinally. The male may stay at least until eggs are hatched, but not much longer (Table 5 ). Brood size is moderately large, with 19– 45 eggs or larvae.

Comments.

This species and the next three are morphologically very similar and can easily be confused. DNA sequence data for COI and 28 S from three of the species nevertheless clearly separate them (Table 4, Fig. 11 ). Eastern and western populations of C. flavescens are also deeply, albeit less, diverged in the mitochondrial COI gene, but, more importantly, identical at the nuclear 28 S gene. It is advisable to apply DNA sequence data to identify species in this complex group. The record from Madagascar is likely confused with the new species C. tuberculatum described in this work.

Figures

Figures 21–29. Dorsal, lateral, and front views of male 21, 24, 27 Ctonoxylon flavescens 22, 25, 28 Ctonoxylon bosqueiae holotype, and 23, 26, 29 Ctonoxylon hirsutum stat. rev.

Figures 10–11. Phylogeny of Ctonoxylon. Node support is given as posterior probabilities above and parsimony bootstrap values below nodes 10 tree topology resulting from the parsimony analysis of 14 morphological characters for all species using implied weighting (Goloboff et al. 2018) 11 partial tree topology redrawn from a previously published Bayesian tree topology based on 1958 nucleotide position from three gene fragments (Jordal 2023). Species found in Madagascar marked in purple.