Ctonoxylon tuberculatum, Jordal, 2024

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 tuberculatum sp. nov.

Figs 30 , 33 , 36

Type material.

Holotype, male: Madagascar, Diana prov., Montagne d’Ambre [GIS: - 12.54, 49.17], 1000 m alt., ex Ficus branch, 03. 11. 2019, B. Jordal, leg. [ ZMUB] . Allotype [ ZMUB] and paratype [ NHMW]: same data as holotype .

Diagnosis.

Two teeth along the anterior margin of pronotum separated by more than width of a tooth; scattered interstrial setae separated within uniseriate rows by more than their length; posterior margin of elytra and declivital interstriae with sharp tubercles, largest tubercles on interstriae 1 and 3.

Description.

Male. Body length 3.0– 3.1 mm, 2.1–2.2 × as long as broad; colour brown. Frons flattened from upper level of eyes to epistoma, surface shrivelled; vestiture of fine short setae. Eyes divided, each part separated by a little more than size of upper half. Antennal funiculus 7 - segmented; club setose, sutures and septum barely indicated. Pronotum coarsely asperate on anterior three quarters, two front teeth separated by little more than width of a tooth, located behind the margin. Anterior lateral margin of prothorax at middle with prominent eye scraper; a sharp carina running from eye scraper to near procoxa; propleural pit absent. Scutellar shield wider than long, oval. Elytral striae impressed, punctures irregular and small; interstriae rounded, densely micropunctate, vestiture consisting of uniseriate rows of slightly curved bristle-like setae and fine dense ground vestiture along the suture; elytral suture straight; elytral apex slightly emarginated, along the posterior margin and at each declivital interstriae with small sharp tubercles, at interstriae 1 and 3 tubercles 2–3 × larger. Metanepisternum with mixed short bifid and longer bristle-like setae; metaventrite with simple hair-like setae; these sclerites on its anterior third partly glabrous and with small bifid setae, and with a swollen trace of mesotibia’s resting position. Female as in male, except anterior pair of teeth more closely placed and located along the anterior margin of the pronotum, and surface of the frons smooth.

Etymology.

The Latin adjective tuberculatus in its neuter form, reflecting the tubercles on declivital interstriae which are more prominent than in related species.

Distribution and biology.

Only known from the holotype locality in Madagascar where it was collected from very thick bark of a fallen Ficus branch ( Moraceae ), 7 cm in diameter. Two pairs were collected at the early stage of tunnel construction, including a mating niche with a short egg tunnel.

Comments.

Previous records of C. flavescens from Madagascar are most likely C. tuberculatum as these two species are very similar. This could also be the case for records of C. montanum (recorded as C. longipilum ), in which the female mainly differs by the more closely set anterior teeth on the pronotum, and the stouter body. These two species are therefore removed from the list of Malagasy species.

Figures

Figures 30–38. Dorsal, lateral, and front views of 30, 33, 36 Ctonoxylon tuberculatum sp. nov. male holotype 31, 34, 37 Ctonoxylon longipilum female (= C. montanum), and 32, 35, 38 Ctonoxylon nodosum male holotype (= C. montanum).