Liodessus altoperuensis, Balke & Megna & Zenteno & Figueroa & Hendrich, 2020

Balke, Michael, Megna, Yoandri S., Zenteno, Nilver, Figueroa, Luis & Hendrich, Lars, 2020, Two new species of Liodessus Guignot, 1939 diving beetles from Northern Peru (Coleoptera, Dytiscidae, Hydroporinae), Alpine Entomology 4, pp. 173-178 : 173

Liodessus altoperuensis sp. nov. Figs 1 E , 2 B , 3 D-F , 4 , 6

Type locality.

Peru, San Pablo, Tumbaden District, Alto Peru, -6.902, -78.603.

Holotype.

Male (MUSM): Peru: Cajamarca, San Pablo, Tumbaden District, Alto Peru, 3933 m, 8.ix.2018, -6.902, -78.603, Y. S. Megna & N. Zenteno (PER_YSM_2018_50).

30 Paratypes

(MUSM, ZSM). 28 exs., same data as holotype. 1 ex. Peru: Cajamarca, Cajamarca, Encañada District, Conga, 4030 m, 7.ix.2018, -6.934, -78.442, Y. S. Megna & N. Zenteno (PER_YSM_2018_46); 1 ex. Peru: Cajamarca, San Pablo, Tumbaden District, Alto Peru, 3928 m, 8.ix.2018, -6.887, -78.595, Y. S. Megna & N. Zenteno (PER_YSM_2018_47).

Description of holotype.

Habitus with little discontinuity between pronotum and elytra, therefore appearing more parallel sided (Fig. 1E ). Total length: 2.1 mm; length without head 1.8 mm; maximum width: 1.0 mm.

Colouration.

Blackish dorsally and ventrally (as in Fig. 1E ).

Surface sculpture.

Head with faint microreticulation, frons and clypeus more or less smooth and with few setiferous punctures; with distinct microreticulation but without punctures posteriorly of a faint cervical line. Pronotum and elytron shiny; with dense and coarse setiferous punctation; pronotum with faint microreticulation along anterior margin and towards pronotal disc.

Structures.

Antenna stout. Head with faint cervical line that dissolves into serial punctures laterally; with rounded clypeus. Pronotum with distinct lateral bead; with distinct and deep basal striae (as in Fig. 1E ). Elytron faint basal striae only obvious under certain angles of illumination; without sutural line. Without basal epipleural transverse carina. Metathoracic wings short, about half the length of elytron (as in Fig. 2B ).

Genitalia.

Median lobe of aedeagus with inner side comparably straight in lateral view, tip slightly bent and comparably robust; in ventral view slender and gently narrowed towards tip (Figs 3D, E ); lateral lobes (parameres) bisegmented and narrow, very typical for the genus (Fig. 3F ).

Variation.

Total length: 1.9-2.2 mm; length without head: 1.7-1.8 mm; maximum width: 0.9-1.0 mm. The elytral stria can be short yet well visible to very faint to absent. We assessed the length of the metathoracic wings in 10 specimens, which all had the same wing length. This does not rule out the possibility that a certain number of specimens can be fully winged.

Female.

Dorsal surface as in male, shiny (Fig. 2B ).

BOLD platform.

We provided 10 entries in the “COLLI” project, all retrieved in one cluster. Assignment to that cluster was unambiguous, meaning all specimens were correctly assigned to this morphologically delineated species.

Etymology.

Named after the type area. The name is an adjective in the nominative singular.

Comparative notes.

The species is well characterized by its smaller size, almost entirely black coloration, elytral plica very short or absent, shape of male genitalia and cox1 signature.

Distribution.

Only known from the high Andes in north western Peru (Fig. 4 ).

Habitat.

Shallow and exposed peatland puddles, collected with strainer out of mats of vegetation including mosses (Fig. 6 ).

Figures

Figure 1. Liodessus spp.: Dorsal habitus of Liodessus caxamarca sp. nov., female paratypes from locality PER _ YSM _ 2018 _ 046 (A), PER _ YSM _ 2018 _ 047 (B), PER _ YSM _ 2018 _ 046 (C), male paratype PER _ YSM _ 2018 _ 046 (D); Liodessus altoperuensis sp. nov., male paratype from locality PER _ YSM _ 2018 _ 050 (E).

Figure 2. Liodessus spp., female paratypes: Metathoracic wing of paratypes of Liodessus caxamarca sp. nov. (A); Liodessus altoperuensis sp. nov. (B).

Figure 3. Liodessus spp. males: Liodessus caxamarca sp. nov., holotype, median lobe of aedeagus in ventral view (A), same in lateral view (B), right paramere external surface view (C); Liodessus altoperuensis sp. nov. holotype, median lobe of aedeagus in ventral view (D), same in lateral view (E), right paramere external surface view (F).

Figure 4. Distribution area (orange dot) of Liodessus caxamarca sp. nov. and Liodessus altoperuensis sp. nov. in the northern Andes of Peru.

Figure 6. Habitats and landscapes at localities Cajamarca, Cajamarca, Encanada District, Conga, 4030 m [PER _ YSM _ 2018 _ 046] (A, B) and Cajamarca, San Pablo, Tumbaden District, Alto Peru, 3935 m [PER _ YSM _ 2018 _ 51] (C, D).