Radicitus Short & García, 2014

Short, Andrew Edward Z. & García, Mauricio, 2014, A new genus of egg case-carrying water scavenger beetle from the Guiana Shield (Coleoptera: Hydrophilidae: Acidocerinae), Zootaxa 3835 (2), pp. 251-262 : 252

Radicitus Short & García gen. n.

Type species. Radicitus ayacucho Short & García sp. n.

Diagnosis. Medium sized beetles, total body length: 4.5–6.2 mm. Antennae with nine antennomeres, including three-segmented club ( Fig. 3 ). Maxillary palps short, shorter than the width of the head. Prosternum not carinate. Elytra without sutural striae ( Fig. 4 ). Mesoventrite with longitudinal carina medially which is elevated and forming a posteriorly pointing process ( Fig. 5 A). Fifth abdominal ventrite evenly rounded, without apical emargination or coarse setae ( Fig. 6 ). Metafemora with pubescence along anterior half on basal three-quarters ( Fig. 5 B). Aedeagus with basal piece extremely short ( Fig. 7 ).

Description. Color. Dorsum dark brown, the margins of pronotum and elytra sometimes slightly paler.

Head. Antennae with nine antennomeres, including three-segmented pubescent club. Maxillary palps curving inward; short, distinctly shorter than the width of the head. Apical palpomere distinctly shorter than penultimate palpomere. Labial palps short, distinctly shorter than mentum width. Mentum slightly concave with a few scattered setae ( Fig. 3 ). Frons with series of irregular systematic, setae bearing punctures anterior to each eye. Systematic punctures also present on clypeus and labrum but blend with ground punctation, appearing almost absent. Eyes slightly bulging laterally, interrupting the outline of the head. Gular sutures subparallel and moderately close.

Thorax. Pronotum with systematic punctation in lateral thirds, each puncture usually bearing a short seta. Prosternum sometimes bulging but not carinate medially; slightly elevated anteromedially into a small tooth. Mesoventrite with anapleural sutures distinctly concave ( Fig. 5 A). Mesoventrite with a conical, strongly elevated projection ( Fig. 5 A), which is directed posteriorly. Metaventrite without posteromedial projection between metacoxae. Elytra with indistinct and irregular rows systematic punctures bearing short setae. Each elytron with ten rows of weakly to moderately impressed punctate striae, but without a sutural stria ( Fig. 4 ). Procoxae set with setae, but without thickened spines. Metafemora pubescent along anterior half on basal three-quarters ( Fig. 5 B). All tarsi with five segments; with short, sparse setae on dorsal face but without long natatory setae. Ventral surface of tarsomeres 1- 4 set with two rows of short brush-like setae.

Abdomen. Abdomen with five exposed ventrites that are covered with a dense, fine, short pubescence. Third laterosternite without a ribbed stridulatory file. Fifth ventrite entire, without a medioapical emargination or coarse bristles ( Fig. 6 ). Aedeagus with abbreviated basal piece ( Fig. 7 ).

Etymology. Radicitus (derived from the Latin radix, root), meaning ‘by the roots’, referring to the habitat of known members of the genus. Masculine.

Figures

FIGURE 3. Heads of Radicitus spp., ventral view. A) R. ayacucho, B) R. granitum.

FIGURE 4. Elytra of Radicitus spp. A) R. ayacucho, B) R. granitum.

FIGURE 5. Details of Radicitus granitum. A) thoracic sternum. B) metafemur.

FIGURE 6. Abdominal ventrites of Radicitus spp. A) R. ayacucho, B) R. granitum.

FIGURE 7. Aedeagi of Radicitus spp. A) R. ayacucho, B) R. surinamensis, C) R. cf. granitum (Suriname), D) R. granitum (Venezuela).