Pseudolepturges triplarinus, de L. Nascimento & Perger, 2018

de L. Nascimento, Francisco E. & Perger, Robert, 2018, Genus Pseudolepturges Gilmour (1957) (Coleoptera: Cerambycidae: Lamiinae): a new species from Bolivia, key to the species of the genus and first reports of a possible Pseudomyrmex ant mimic in longhorn beetles, Journal of Natural History 52 (21 - 22), pp. 1463-1471 : 1465-1469

Pseudolepturges triplarinus sp. nov.

( Figure 2 (a,b,c,g); Figure 3 (a,b))

Holotype male. General integument yellowish; head, prothorax and ventral area light yellowish brown; mouth parts, except jaws (light yellowish brown, blackish at apex), antennomeres and legs yellowish; elytra light yellowish brown at anterior third, slightly yellowish towards apex; prosternal process blackish at middle (laminar part). Pubescence pale yellow; setae dark brown and blackish.

Head. Head with abundant pubescence, not obscuring integument, except on gulamentum area (smooth and glabrous). Median groove extending to vertex area, behind upper eye lobes; antennal tubercles slightly elevated. Frontoclypeal suture and labrum with erected elongated blackish setae; labial and maxillary palpomere IV fusiform. Upper eye lobes with five rows of ommatidia; distance between upper eye lobes about twice width of an upper eye lobe; lower eye lobes, about 1.8 times genae length. Antennae about 1.3 times body length; reaching elytral apex at mid-length of antennomere VIII; abundant short dark brown decumbent setae intercalated by yellowish setae, not obscuring integument; antenomeres III– VI with sparse short, thick blackish setae at internal side. Antennal formula (ratio) based on antennomere III: scape = 1.28; pedicel = 0.13; IV = 0.98; V = 0.85; VI = 0.76; VII = 0.75; VIII = 0.67; IX = 0.60; X = 0.55; XI = 0.60.

Thorax. Prothorax about 1.2 times wider than long; anterior margin and posterior fifth constricted; sides with tubercle slightly projected at posterior third; pronotum slightly convex; surface finely,abundantly punctate; posterior fifth with a coarsely transverse row of punctures; surface with abundant pubescence, not obscuring integument. Prosternum with abundant pubescence, not obscuring integument; prosternal process laminar at middle; procoxal cavity closed behind; mesosternal process one-fifth the diameter of a mesocoxal cavity, raised at apex; mesocoxal cavity opened laterally; meso- and metasternum with abundant pubescence homogeneously distributed, not obscuring integument. Elytra slightly widened at anterior fifth; apex obliquely truncated; each elytron with oblique dense band of pubescence starting at anterior third, widened towards elytral suture; elytral pubescence more abundant on the posterior half, not obscuring integument. Legs with moderately abundant pubescence, not obscuring integument; femora clavate; distal half of tibiae and tarsomere with sparse short, thick blackish setae; metatarsomere I longer than II+III together.

Abdomen. Abdomen with abundant pubescence, not obscuring integument; abdominal ventrite I about 1.5 the II length; II–IV slightly decreasing in length; V trapezoidal, apex with short, thick blackish setae.

Dimensions (in mm), holotype male. Total length, 3.90; prothorax length, 0.80; greatest width of prothorax, 0. 90; anterior width of prothorax, 0.80; posterior width of prothorax, 0.80; humeral width, 1.20; elytral length 2.80.

Type material

Holotype male from BOLIVIA, Santa Cruz department, La Guardia ( Chiquitano forest ; – 17.883056 S /– 63.317778 W; 480 m above sea level), January / February 2017, on a Triplaris americana tree, manually collected, R. Perger col. ( MZSP).

Etymology

The specific epithet, triplarinus , refers to the possible ant model Pseudomyrmex triplarinus and the possible host tree Triplaris americana .

Remarks

Pseudolepturges triplarinus sp. nov. can be easily differentiated from the other two species in the genus by the general light orange-yellowish integument;the anterior fourth of the elytra with a transversal, yellowish-whitish band of pubescence, demarcated from the colour of the integument, narrowing at middle, and the posterior third covered with indistinct yellowish-whitish pubescence, not distinctly demarcated from the colour of the integument.

In P. caesius the integument is dark brown, the anterior half of the elytra possesses a heart-shaped patch of grey pubescence with one additional patch at each side, and the posterior fourth of the elytra is covered by greyish pubescence ( Figure 3e ).

In P. rufulus the integument of the head, pronotum and proximal third of the elytra are red, the remaining integument of the elytra is dark brown. The elytra have in the anterior third and posterior fourth a transversal, narrow band of whitish pubescence, the anterior one can be with a side branch.

Pseudolepturges triplarinus sp. nov. differs from P. rufulus also by the longer lower eye lobes, about 1.8 times the gena length ( Figure 2g ). In P. rufulus the lower ocular lobes are about 0.7 times the gena length ( Figure 2h ). Although Gilmour (1957) has mentioned the small lower eye lobes as a generic feature, Monné and Monné (2007) do not mention it (translated): ‘The characters that distinguish Pseudolepturges from other Neotropical genera of Acanthocinini with elytra lacking erect setae are: elytra lacking centro-basal crest and without lateral carinae, prothorax with parallel sides and lateral tubercle placed at posterior third, pronotum without tubercles, sulcus at base of pronotum interrupted by the insertion of the tubercles, antennae with 11 antenomeres and the first metatarsomere longer than the next two’. Perhaps this is due to the variation of the size of the eye lobes in several other genera and most probably this is a specific characteristic, as Pseudolepturges was originally created as monotypic.

The individual of Pseudolepturges triplarinus sp. nov. was observed on the damaged stem of a Triplaris americana tree, running in close proximity to ants of Pseudomyrmex triplarinus Weddell ( Figure 4 (b)). When the second author approached to collect the beetle manually, the ants emerged from the tree internodes and came closer. Although both, the second author and the ants represented a threat for the beetle, it proceeded to run between the ants without being attacked by the latter.

The about similar body length (workers of Pseudomyrmex triplarinus have a body length of 5.35 ± 0.44 mm, n = 25), the colour (compare Figures 4 (b) and 2(a)), the behaviour and the close co-occurrence suggest that Pseudolepturges triplarinus sp. nov. imitates Pseudomyrmex triplarinus (discussed below).

Figures

Figure 2. Comparison between Pseudolepturges triplarinus sp. nov. and Pseudolepturges rufulus (Bates): (a,b,c,g) P. triplarinus sp. nov. holotype male; (a) dorsal view, (b) ventral view; (c) lateral view; (g) frontal view. (d,e,f,h) P. rufulus, male; (d) dorsal view; (e) ventral view; (f) lateral view; (h) frontal view.

Figure 3. Comparison between Pseudolepturges triplarinus sp. nov., Pseudolepturges rufulus (Bates) and Pseudolepturges caesius Monné & Monné: (a,b) Pseudolepturges triplarinus sp. nov. holotype male: (a) head in lateral view; (b) anterior half of elytra; (c,d) Pseudolepturges rufulus (Bates), male; (a) head in lateral view; (b) anterior half of elytra. (e) Pseudolepturges caesius Monné & Monné, holotype female, dorsal view.

Figure 4. Habitat of Pseudolepturges triplarinus sp. nov. and its potential ant model Pseudomyrmex triplarinus Weddell: (a) Trees of Triplaris americana (L.) Pav. Ex Meisn. (indicated by white arrows). (b) Ants of Pseudomyrmex triplarinus on the stem of T. americana.