Bidessus longistriga Régimbart, 1895

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 : 6-8

Bidessus longistriga Régimbart, 1895

Figs 2C , 3G

Bidessus longistriga Régimbart, 1895: 79 .

Bidessus longistriga – Alluaud 1900: 59. — Zimmermann 1920: 54. — Guignot 1959: 254. — Bistr̂m 1985: 7. — Rocchi 1991: 85. — Nilsson 2001: 115. — Pederzani & Rocchi 2009: 93. — Nilsson & Hajek 2020: 104.

Diagnostic characters

Head frontally not margined but provided with a shallow, transverse depression slightly posterior to anterior edge of head (between eyes). Pronotum on disc with a broad impunctate area or with a few fine punctures, distinctly sparser than punctures at frontal and posterior edge. Pronotal striae at base deeply impressed. Pronotal striae with a distinct angle (not smoothly curved). Basal striae of elytra long. Sutural lines distinct; anteriorly and posteriorly lines fade away; transformed to row of punctures. Punctures on both side of basal striae of unequal size; distinctly coarser on inner side. Apical sternite with fine, slightly irregular punctures. Female with outline of elytra posteriorly smooth (minor extension absent). Penis in lateral view slender, curved but medially somewhat straightened. Penis apex not distinctly extended ( Fig. 3G ).

Length of body 1.6–1.8 mm.

Material examined

283 specimens ( BMNH, NHRS, NMW, PBZT / MBC, DEUA) from provinces Antsiranana, Mahajanga, Toliara, Fianarantsoa and Toamasina (see Supplementary File 1).

Distribution

Endemic species to Madagascar but widely distributed on the island in lowland areas below 800 m a.s.l. ( Fig. 4A ).

Collecting circumstances

An apt flier that can be collected at light. At low altitudes on both east and west coast, found in a variety of stagnant waters (rice fields, ponds, pools in riverbeds), and in slow-flowing parts of rivers and canals. Often occurs sympatrically with B. perexiguus .

Figures

Fig. 2. Habitus photographs of Malagasy species of Bidessus Sharp, 1882. A. B. nesioticus Guignot, 1956 (NHRS-JLKB000025031). B. B. perexiguus Kolbe, 1883 (NHRS-JLKB000025029). C. B. longistriga Régimbart, 1895 (NHRS-JLKB000025028).

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).