Balgus eganensis ( Bonvouloir, 1875 )

Barbosa, Felipe Francisco, 2016, Revision and phylogeny of the genus Balgus Fleutiaux, 1920 (Coleoptera, Elateridae, Thylacosterninae), Zootaxa 4083 (4), pp. 451-482 : 457-458

Balgus eganensis ( Bonvouloir, 1875)

( Figure 3 )

Pterotarsus inaequalis Dejean, 1837: 95 - Bonvouloir, 1875: 836 (in litteris).

Pterotarsus Egaensis Bonvouloir, 1875: 832 , 836 (original description).

Balgus egaensis Fleutiaux, 1920: 97 (new combination, correction of the specific epithet under the article 32.5.2.5 of ICZN, Egaensis to egaensis ).

Balgus eganensis Schenkling, 1928: 7 (catalogue, correction of the specific epithet, egaensis to eganensis ); Blackwelder, 1944: 275 (catalogue); Chassain & Touroult, 2013: 75, 77, 79, 81 (redescription, new distribution register, aedeagus described).

Diagnosis. Subcylindrical body ( Figures 3A, B, C, F ); pronotum abruptly attenuate at the anterior third; the dorsal and ventral regions are covered with yellow or golden pubescence, moderately dense on the head and pronotum, scattered on the elytra; ventrite 5 triangular, strong and gradually narrowed from base to apex, which is truncated, with no curved apex; ventrite 5 with longitudinal median carina forming two small teeth.

Redescription. Subcylindrical body, narrowing abruptly on the posterior third. Elytra about two and half times as long as pronotum. Dorsal and ventral regions covered with yellow or golden pubescence, moderately dense on head and pronotum, scattered on elytra.

Color: black, except: first antennomere dark brown or light brown; antennal rami yellow; elytral bands light to dark brown or reddish brown; tarsi light brown or yellow.

Head ( Figure 3D ): punctate, with deep longitudinal median anterior depression continuing posteriorly on the longitudinal groove on the vertex, not V-shaped. Eye with spherical surface in lateral view, dorsal margin not sinuous.

Thorax: subcylindrical prothorax ( Figures 3A, B, C, F ), almost as long as wide; margins sinuous; abruptly attenuate at anterior third; prominent tubercles; posterior half of pronotum with posterolateral oblong tubercle, posterolateral rounded tubercle and posteromedian rounded tubercle; anterior half of the pronotum with anterolateral oblong tubercle, anterolateral rounded tubercle and anteromedian rounded tubercle. Pronotal sculpture formed by deep punctations, sparser and denser on intervals of the tubercles. Scutellum rectangular to trapezoidal, slightly longer than wide, subparallel margins, carinate on the median region. Lateral thoracic sclerites hidden under elytra. Antennal acetabulum very deep next to the prosternal process. Prosternal process gradually attenuate towards the posterior margin, more or less rounded lateral margin. Prosternum, mesoventrite and metaventrite densely punctate. Elytra ( Figures 3A, C, F ) finely and sparsely punctate; acuminate apex; basal fifth with five elevated striae and with tranverse rugosities; two elongate central tubercles which seem to be the continuation of the second basal stria, first at the middle and second on the posterior third; elongated lateral tubercle longer, which seems to be the continuation of the fourth basal stria; another lateral tubercle seems a continuation of fifth basal stria.

Abdominal ventrites: densely punctate; ventrite 5 ( Figure 3E ) triangular, with longitudinal median carina forming two small teeth; strong and gradually narrowed from base to apex, which is truncated, not curved.

Female genitalia: apex of available female genitalia was damaged; only the baculum could be observed. Baculi, at least at apical third, separated by about the width of a baculum.

Aedeagus: paramere tapering apically; acuminate at apex and with many setae. Penis tapering apically; acuminate at the apex, in lateral view slightly curved ventrally. Length of the phalobasis about two and a half times paramere length; about three times as wide as paramere. Concavity of the phallobasis in dorsal view, limited to base of the phalobasis (based on Chassain & Touroult, 2013).

Intraspecific variation: size variation (N = 2): length 15.30–18.70 mm (mean = 17 mm); humeral width 5.20– 6.20 mm (mean = 5.70 mm).

Remarks. this species has the most protruding pronotal and elytral tubercles among other Balgus species. It is very similar to B. tuberculosus , but B. eganensis can easily be distinguished by: darker color; narrowest body shape; abruptly attenuate pronotum in anterior third; elytral apex acuminate, narrowed abruptly; and ventrite 5 strong and gradually narrowed from base to apex, which is truncated, without curved apex.

Etymology. [ Ega +adjective suffix of location]. Referring to the village of Ega (currently municipality of Tefé, Amazonas (AM), Brazil), where specimens were collected by the naturalist H. W. Bates.

Material examined. 1 ex., Brazil, Amazonas (AM), Ega (currently municipality of Tefé ), E. Fleutiaux det., 1904, BNHM; 1 ex., Ecuador, E. Fleutiaux coll., MNHN .

Distribution. Brazil (AM), Ecuador and French Guiana ( Figure 12 ).

Type locality. Brazil, Amazonas (AM), Ega (currently municipality of Tefé ).

Figures

FIGURE 3. Balgus eganensis (Bonvouloir, 1875): A) habitus, dorsal view; B) habitus, ventral view; C) habitus, lateral view; D) head, frontal view; E) ventrite 5, ventral view; F) pronotum and elytra, dorsal view. Scales: 2 mm.

FIGURE 12. Geographical distribution of Balgus albofasciatus (Bonvouloir, 1875), Balgus eganensis (Bonvouloir, 1875) and Balgus eschscholtzi (Laporte, 1835).