Laccophilus alluaudi, Regimbart, 1900

Manuel, Michaël & Ramahandrison, Andriamirado T., 2020, Four new species of the diving beetle genus Laccophilus Leach, 1815 from Madagascar (Coleoptera, Dytiscidae, Laccophilini), Zootaxa 4822 (4), pp. 482-502 : 493-494

Key to species of the Laccophilus alluaudi -group (adapted and updated from Biström et al. 2015)

1. Large species, body length 5.0– 5.8 mm; along medial part of anterior pronotal margin with distinct dark transverse band; dark elytral vittae hollow, with pale enclosed area sharply delimited and of same colour as pale stripes in-between dark vittae................................................................................................ L. seyrigi

- Smaller species; along medial part of anterior pronotal margin without distinct dark transverse band; dark elytral vittae entirely dark or if hollow, with pale enclosed area diffusely delimited and of darker colour than pale stripes in-between dark vittae.. 2

2. Humeral region of elytron with well-delimited and contrasted dark brown marking(s) (anterior prolongation of lateral dark elytral vittae); median lobe as in Biström et al. (2015), Figs. 230–231...................................... L. comes

- Humeral region of elytron entirely testaceous or at most with faint, poorly delimited pale brown marking; median lobe different................................................................................................. 3

3. Median lobe in lateral view with dorsal outline evenly curved from base to apex ( Biström et al. 2015, Fig. 237); in ventral view with distinct process near base on right side ( Biström et al. 2015, Fig. 238); species from the Comoro Islands.... L. tigrinus

- Median lobe in lateral view with dorsal outline angled close to base; in ventral view lacking latero-basal process; species from Madagascar.......................................................................................... 4

4. Ventral surface of prothorax brown....................................................................... 5

- Ventral surface of prothorax testaceous.................................................................... 6

5. Metacoxal plates testaceous with only narrow area along lateral margin brown; mesotibia strongly modified, especially in male: broad with dorsal outline strongly curved and ventral outline straight ( Fig. 5 )..................... L. leguyaderi sp. nov.

- Metacoxal plates with lateral dark area much more extended; mesotibia unmodified ( Fig. 6 ).......... L. bergsteni sp. nov.

6. Ventral surface entirely testaceous........................................................................ 7

- Ventral surface with metacoxal plates conspicuously darkened, at least in lateral half................................ 8

7. Dark elytral vittae ending close to anterior margin of elytron; median lobe in ventral view with marked constriction shortly before apex ( Biström et al. 2015, Fig. 241); known only from the Isalo Massif in central-southern Madagascar... L. pseustes

- Dark elytral vittae ending farther from anterior margin of elytron; median lobe in ventral view without marked constriction shortly before apex ( Fig. 18 ); known only from the Makay massif in central-southern Madgascar......... L. makay sp. nov.

8. Median lobe in ventral view from angle to apex almost evenly broad and almost straight ( Biström et al. 2015, Fig. 236).................................................................................................. L. furthi

- Median lobe in ventral view from angle to apex of unequal width and strongly twisted ( Fig. 19–22 )............ L. alluaudi

Figures

FIGURES 5–8. Ventral surface of: (5) Laccophilus leguyaderi sp. nov. (holotype); (6) Laccophilus bergsteni sp. nov. (holotype); (7) Laccophilus makay sp. nov. (holotype); (8) Laccophilus alluaudi (male specimen from Isalo massif). Scale bar: 1 mm.

FIGURES 9–22. Median lobe of aedeagus in lateral (9–15) and ventral (16–22) view of: (9, 16) Laccophilus leguyaderi sp. nov. (holotype); (10, 17) Laccophilus bergsteni sp. nov. (holotype); (11, 18) Laccophilus makay sp. nov. (holotype); Laccophilus alluaudi, male specimens from (12, 19) Montagne d’Ambre, (13, 14, 20, 21) Isalo massif, and (15, 22) Ibity massif. Scale bar: 0.1 mm.