A new species of Bidessus from Anjozorobe-Angavo and a review of Malagasy Bidessus (Coleoptera, Dytiscidae) Author Bergsten, Johannes 64120AE6-1D4B-4C29-AA37-46DA7C7A26A8 Department of Zoology, Swedish Museum of Natural History, Box 50007, SE- 10405 Stockholm, Sweden. Department of Entomology, Faculty of Sciences, Box 906, University of Antananarivo, 101 Antananarivo, Madagascar. Finnish Museum of Natural History, Zoology Unit, P. O. Box 17, FI- 00014 University of Helsinki, Finland. johannes.bergsten@nrm.se Author Ranarilalatiana, Tolotra 4E61E817-7646-4993-A25A-78E2B160F5B8 Department of Entomology, Faculty of Sciences, Box 906, University of Antananarivo, 101 Antananarivo, Madagascar. t.ranarilalatiana@gmail.com Author Biström, Olof 2F25C707-9602-438B-BCCE-D7A9B7103BC1 Finnish Museum of Natural History, Zoology Unit, P. O. Box 17, FI- 00014 University of Helsinki, Finland olof.bistrom@helsinki.fi text European Journal of Taxonomy 2020 2020-10-05 720 1 18 journal article 9764 10.5852/ejt.2020.720.1109 545aa4ea-1874-4f74-a4c4-a2aeb97ed657 2118-9773 4068355 0CF83E89-2532-407B-921F-C05F9A29C68D Bidessus nesioticus Guignot, 1956 Figs 2A , 3E Bidessus nesioticus Guignot, 1956: 77 . Bidessus nesioticus – Bistr̂m 1985: 35. — Rocchi 1991: 85 . — Nilsson 2001: 115 . — Nilsson & Hajek 2020: 104 . Fig. 5. Type locality [MAD14-78] for Bidessus anjozorobe sp. nov. in Anjozorobe forest in Anjozorobe- Angavo protected area on the Central Highlands. A glade in the rainforest with marsh vegetation. Multiple individuals of Bidessus anjozorobe sp. nov. were found by tramping in the vegetation at the edges of the marsh. Diagnostic characters Head frontally not margined; somewhat posterior to frontal edge (between eyes) with a transverse depression which becomes indistinct medially. Pronotum on disc with a quite broad, almost impunctate area (fine scattered punctures discernible). Pronotal striae quite deeply impressed, distinctly angled (striae not smoothly curved). Basal striae of elytra moderately long, not deeply impressed. Sutural lines distinct; posteriorly they fade away a short distance before apex; anteriorly, distinguished almost up to posterior edge of pronotum. Size of punctures on each side of basal striae rather fine, almost of equal size. Apical ventrite with fine, quite sparse punctures. Female with posterior outline of elytra smooth (no minor extension). Penis, dorsal aspect comparatively broad and short; in lateral aspect curved. Apex of penis not distinctly extended ( Fig. 3E ). Body length 1.6–1.7 mm . Shiny, dorsally not microsculptured (frontally on head fragments of reticulation distinguished). General color of body dark piceous to blackish. Pronotum discally on each side with a well-delimited, testaceous spot. Elytra with vague, slightly paler, longitudinal markings. Apex of elytra slightly paler. Base of antenna and legs in part slightly paler. Material examined Holotype MADAGASCAR • 1 ♂ ; Ankaratra , Tsiafajavona ; 2500 m a.s.l. ; Jun. 1947 ; J. Millot leg.; MNHN . [Note that Bistr̂m (1985) during his revision of the group, was unable to locate this holotype that we have since rediscovered.] Additional material MADAGASCAR • 1 spec. ; Antananarivo former province, Vakinankaratra region , Manjakatompo Stn Forestière, Anosiarivo ; 19.34489° S , 047.30414° E ; 2073 m a.s.l. ; 24 Jan. 2012 ; T. Ranarilalatiana and J.H. Randriamihaja leg.; collecting event MAD-MJK12-13; lake near source; NHRS-JLKB000025031 • 20 specs (preserved in ethanol); same collection data as for preceding; NHRS-JLKB000024967 • 5 specs; same collection data as for preceding; FMNH • 5 specs; same collection data as for preceding; PBZT / MBC • 5 specs; same collection data as for preceding; BMNH • 5 specs; same collection data as for preceding; DEUA • 18 specs (preserved in ethanol); Fianarantsoa former province, Haute Matsiatra region , Andringitra NP, lake north east of camp 3; 22.17373° S , 46.9016° E ; 2026 m a.s.l. ; 2 Dec. 2013 ; J.H. Randriamihaja and T. Ranarilalatiana leg.; collecting event MAD13-33; small lake in open area; NHRS-JLKB000025023 • 5 specs; same collection data as for preceding; PBZT / MBC • 4 specs; Fianarantsoa former province, Ankaratra massif, ca 2.7 km WNW of Manjakatompo ; 19°21′57″ S , 47°18′22.5″ E ; 1814 m a.s.l. ; 19 Dec. 2017 ; Ramahandrison and Manuel leg.; large grassy temporary pond, beneath slope with pine trees, with Conchostraca crustaceans; CMM . Distribution Endemic species to Madagascar and known from the Ankaratra and Andringitra mountain massifs in central Madagascar ( Fig. 4C ). Collecting circumstances This is a high-elevation alpine species on Madagascar , only known from above 1800 m altitude. The type material was collected at 2500 m altitude near the Ankaratra peak Tsiafajavona in 1947. TR and Jacquelin Herisahala Randriamihaja found it in an overflooded glade near a source in 2012 at a slightly lower elevation on Ankaratra ( 2073 m ) ( Fig. 6A ). Additionally, they discovered the species for the first time outside Ankaratra in a small lake with vegetation at 2026 m elevation in Andringitra NP further south in 2013 ( Fig. 6B ). A few specimens were collected in a clearwater grassy pond as low as 1814 m in the Ankaratra mountain by A.T. Ramahandrison and M. Manuel in 2017.