Chortastus minimus Hagedorn, 1909

Jordal, Bjarte H., 2025, Taxonomic revision of the rare Afrotropical genus Chortastus Schaufuss (Coleoptera: Scolytinae), Zootaxa 5647 (1), pp. 77-84 : 80

Chortastus minimus Hagedorn, 1909

( Figs 9–18 )

Chortastus minimus Hagedorn, 1909: 738 .

Chortastus medius Eggers, 1924: 100 , syn. nov.

Chortastus agnatus Eggers, 1935: 301 , synonym by Browne, 1973.

Chortastus sulcatus Eggers, 1935: 301 , synonym by Browne, 1973

Chortastus brunneus Nunberg, 1967: 317 , synonym of C. medius by Browne, 1973.

Afrochramesus baguenai Schedl, 1971: 197 , synonym of C. medius by Beaver, 1998.

Type material. Syntypes: Cameroon [ ZMHB]. Syntype of Chortastus medius : Congostaat [ Democratic Republic of the Congo], Albertville [Kalemie] 1.XII.1918, R. Mayné, leg. [ MRCA] . Lectotype of Chortastus agnatus : Cameroon, Conradt, leg. [ USNM] . Holotype of Chortastus sulcatus : [ Democratic Republic of the Congo], Sankuru, 1.IV.1925, ex Staudtia gabonensis, Lt. Ghesquière , leg. [ MRCA] . Holoty,pe of Chortastus brunneus : [ Democratic Republic of the Congo], Bas-Congo, Kimwenza, 1.IV.1956, R. P. Van Eyen, leg. [ MRCA].

Other material. Congo-Brazzaville [Republic of Congo], Sibiti, leg. Endrödy-Younga, 27.11.1963 [ NHMW]. Democratic Republic of the Congo, Mulongo, [Haut-Lomami], 20.5.1930, P. Gerard, leg. [ NHMW]; Yangambi, 14.12.1951, K. E. Schedl, leg. [ NHMW] and 17.VII.1952 [ MRCA] .

Diagnosis. Body length 1.6–2.7 mm, 2.1–2.2 × as long as wide. Male frons with long golden setae from vertex and near eye margin reaching near epistoma, female frons with very short erect setae evenly distributed over entire frons; pronotum and elytra with similar type of setae, on elytral interstriae in a single row or in variably confused multiple rows; interstriae 2 on declivity slightly impressed, smooth and glabrous, interstriae 3 on lower half of declivity with a slightly elevated blunt ridge.

Distribution. Democratic Republic of the Congo, Republic of Congo, Cameroon, Angola.

Host plant: Staudtia stipitata ( Myristicaceae ).

Remarks. Comparison of (holo-) types of C. minimus , C. medius , C. sulcatus , C. brunneus and C. agnatus , and a paratype of C. baguenai revealed a gradual variation from smallest ( minimus , agnatus and sulcatus ) to medium ( baguenai ) to largest ( medius ), and from slightly more spaced setae ( minimus and agnatus ) to a little denser ( sulcatus , brunneus and medius ). Because all these species were described from nearby locations in the greater Congo basin, and that body size is known to vary a great deal in phloem feeding bark beetles, these intergrading types are inferred as conspecific.

Figures

FIGURES 9–18. Dorsal, lateral, posterior and front view of Chortastus minimus. 9–13, a specimen similar to C. agnatus holotype (synonym); 14–18, a specimen similar to C. medius holotype (synonym). 9–12, 14, 15, 17, 18 males, 13 and 16 females.