Bidessus cf. ceratus Guignot, 1941

Bergsten, Johannes, Ranarilalatiana, Tolotra & Biström, Olof, 2020, A new species of Bidessus from Anjozorobe-Angavo and a review of Malagasy Bidessus (Coleoptera, Dytiscidae), European Journal of Taxonomy 720, pp. 1-18 : 5-6

Bidessus cf. ceratus Guignot, 1941

Figs 1B , 3B

Bidessus ceratus Guignot, 1941: 31 .

Bidessus ceratus – Guignot 1959: 257. — Bistr̂m 1985: 20. — Rocchi 1991: 85. — Nilsson 2001: 114. — Pederzani & Rocchi 2009: 93. — Nilsson & Hajek 2020: 104.

Diagnostic characters

Head frontally not margined. Slightly posterior to frontal edge with slight depression and anterior to it with three (sometimes four) transversely located, slight but clearly distinguishable tubercles. Pronotum on disc with a rather broad impunctate area. Pronotal striae distinct but not strongly impressed; striae angled and sinuate. Basal striae of elytra distinct but comparatively short. Sutural lines present but quite weakly developed; anteriorly they end clearly before reaching frontal edge of elytra; posteriorly they are transformed to a row of separate punctures slightly behind middle of elytra. Punctures on each side of elytral striae almost similar; fine, slightly irregularly distributed and somewhat sparse. Ventrite apically with distinct and quite dense punctures. Female with outline of elytra posteriorly smooth (minor process absent). Penis (lateral aspect) comparatively robust, evenly curved; (dorsal aspect), quite broad. Penis apex not distinctly extended ( Fig. 3B ).

Length of body 1.8–2.0 mm.

Material examined

MADAGASCAR • 5 specs; “envir. de Perinet riv. Farimbany” [around Perinet , Farimbany river]; “( Q 800)” [800 m a.s.l.]; 18 Jul. 1970; N. Sanfilippo leg.; FMNH .

Distribution

A species as tentatively defined here distributed in East Africa and Madagascar (see Biström 1985). In Madagascar only known from Moramanga and Analamazaotra NP in east central parts ( Fig. 4D ). However, Pederzani & Rocchi (2009) identified seven specimens collected in southern Madagascar by Gerecke & Goldschmidt in 2001 as B. ceratus (specimens housed at BMNH and NMW). The series, which we have not studied, was collected north of Ranopiso (25.05° S, 46.67° E) near the southern part of Andohahela NP and ca 35 km west of Taolanaro.

Collecting circumstances

According to label information sampled at 800–1000 m a.s.l.

Taxonomic observation

Bidessus ceratus is described from Uganda in eastern continental Africa. When the B. sharpi species group was revised (Bistr̂m 1985), specimens from Madagascar were considered to belong to this species. There are, however, features, which indicate the existence of a separate species in Madagascar. No fresh specimens in ethanol are at present available for DNA analyses and accordingly the earlier interpretation is retained.

Figures

Fig. 1. Habitus photographs of Malagasy species of Bidessus Sharp, 1882. A. B. apicidens Bistr̂m & Sanfilippo, 1986, ♀, paratype, http://id.luomus.fi/GL.8408 (FMNH). B. B. cf. ceratus Guignot, 1941, http://id.luomus.fi/GC.2001 (FMNH). C. B. anjozorobe sp. nov., paratype (NHRS-JLKB000025034). D. B. cf. nero Gschwendtner, 1933 (NHRS-JLKB000025032).

Fig. 3. Male genitalia of the Malagasy species of Bidessus Sharp, 1882. For each subpanel from left to right penis in dorsal view, penis in lateral view and paramere in lateral view. A. B. apicidens Bistr̂m & Sanfilippo, 1986. B. B. cf. ceratus Guignot, 1941. C. B. anjozorobe sp. nov. D. B. cf. nero Gschwendtner, 1933. E. B. nesioticus Guignot, 1956. F. B. perexiguus Kolbe, 1883. G. B. longistriga Régimbart, 1895.

Fig. 4. Distribution maps of the Malagasy species of Bidessus Sharp, 1882. A. B. longistriga Régimbart, 1895. B. B. perexiguus Kolbe, 1883. C. B. cf. nero Gschwendtner, 1933 (circle), B. nesioticus Guignot, 1956 (square), B. anjozorobe sp. nov. (triangle). D. B. apicidens Biström & Sanfilippo, 1986 (square), B. cf. ceratus Guignot, 1941 (circle).