Globulosis García

Short, Andrew Edward Z., García, Mauricio & Girón, Jennifer C., 2017, Revision of the Neotropical water scavenger beetle genus Globulosis García, 2001 (Coleoptera: Hydrophilidae: Acidocerinae), Zootaxa 4232 (2), pp. 271-281 : 273-274

Genus Globulosis García

Globulosis García, 2001: 153

Type species. Globulosis hemisphericus García, 2001 , by original designation.

Differential diagnosis. Small beetles, total body length 1.9–2.3 mm ( Fig. 2 ). Color yellow to dark brown. Body form rounded in dorsal view, and subhemispherical (slightly dorsoventrally compressed). Antennae with eight antennomeres ( Fig. 5 A). Maxillary palps curved inward. Elytra without sutural or other distinct striae. Mesoventrite with a transverse ridge, usually elevated medially into an acute tooth ( Fig. 5 B). Fifth abdominal ventrite with small truncation at apex ( Fig. 6 A).

Description. Head ( Figs. 3 ; 5A). Antennae with eight antennomeres, including three-segmented pubescent club ( Fig. 5 A). Maxillary palps curved inward and long, distinctly longer in length than the width of head just anterior to eyes; inner face of palpomere 2 straight to slightly curved ( Fig. 5 A); apical palpomere slightly longer than penultimate. Labial palps short, distinctly shorter than mentum width. Mentum ( Fig. 5 A) flat and set with a few scattered setae; strongly emarginated anteromedially with a notch extending posteriorly about one-quarter to one-third of its length. Head with ground punctures weakly impressed. Frons ( Fig. 3 ) with series of irregular systematic setiferous punctures anterior to each eye. Systematic punctures also present on clypeus and labrum but blend with ground punctation, appearing almost absent. Eyes ( Fig. 3 ) not bulging, continuous with outline of the head; slightly emarginated anteriorly by a small extension of the frons. Thorax. Pronotum with systematic punctation in lateral thirds, each puncture usually bearing a short seta. Prosternum narrow, not carinate medially ( Fig. 6 B); very slightly elevated in anterior third, and with a transverse crease. Mesoventrite with anapleural sutures distinctly concave ( Fig. 5 B). Mesoventrite with a transverse, triangular ridge medially ( Fig. 5 B). Metaventrite pubescent, with a small indistinct glabrous region posteromedially; with a small posteriorly projecting tooth medially. Elytra without sutural stria or serial punctures ( Fig. 5 C); with irregular rows of systematic punctures bearing short setae, appearing indistinct from surrounding ground punctation. Procoxae set with sparse setae, but without thickened spines ( Fig. 6 B). Hind femora pubescent on all but apical fifth to sixth of ventral face ( Figs. 2 C, F). All tarsi with five tarsomeres; with a few short setae on dorsal face but without long natatory setae. Ventral surface of tarsomeres 1– 4 set with two rows of moderately long articulated spicules. Abdomen. Abdomen with five densely pubescent ventrites, with setae slightly denser medially on each ventrite (6A). Fifth ventrite truncate to very weakly emarginated at apex, and set with a row of coarser yellow setae ( Fig. 6 A). Aedeagus (e.g., Fig. 7 ) with short basal piece, less than one-third the length of the parameres. Median lobe wide, wider than width of parameres.

Larvae. Unknown.

Distribution. Colombia (Meta), Venezuela (Apure, Amazonas, Bolívar), Guyana, Suriname, & Brazil (Amazonas, Pará).

Biology. Recent collecting efforts in Venezuela and Suriname suggest that the genus is primarily found in moving waters, particularly stream margins with detritus. It has been found at elevations from near sea level to 600 m.

Figures

FIGURE 2. Habitus of Globulosis spp. G. hemisphericus (from Suriname): (A) dorsal, (B) lateral, (C) ventral; G. flavus (paratype): (D) dorsal, (E) lateral, (F) ventral. Scale bar 1 mm.

FIGURE 3. Head in frontal view of Globulosis spp. (A) G. hemisphericus, (B) G. flavus. Scale bar: 0.5 mm.

FIGURE 5. Scanning electron micrographs of G. flavus: (A) head, ventral view, (B) mesosternum, (C) dorsal habitus.

FIGURE 6. Scanning electron micrographs of G. flavus: (A) abdominal ventrites, (B) prosternum.

FIGURE 7. Aedeagus of Globulosis spp. (A) G. flavus sp. n. (holotype), (B) G. hemisphericus, reproduced from García, 2001, (C) G. hemisphericus from the upper Berbice, Guyana, (D) G. hemisphericus from Manaus, Brazil, (E) G. hemisphericus from Raleighvallen Nature Reserve, Suriname. Scale bar 0.05 mm.