Globulosis Garcia , 2001

Giron, Jennifer C. & Short, Andrew Edward Z., 2021, The Acidocerinae (Coleoptera, Hydrophilidae): taxonomy, classification, and catalog of species, ZooKeys 1045, pp. 1-236 : 1

Genus Globulosis Garcia, 2001 Figs 1U , 2 , 5 , 30J , 32

Globulosis García, 2001: 153.

Gender.

Masculine.

Type species.

Globulosis hemisphericus García, 2001: 153; by original designation.

Diagnosis.

Small beetles, body length 1.9-2.3 mm. Body shape rounded in dorsal view, strongly convex in lateral view (Fig. 32 ). Surface of head, pronotum and elytra smooth, with moderate to shallow ground punctation. Coloration yellow to dark brown, uniform along body, with paler mouthparts and tarsi (Fig. 32 ). Shape of head relatively oval. Eyes relatively small, anteriorly emarginated (Fig. 32B ), not projected from outline of head. Clypeus trapezoid, with anterior margin mesally broadly emarginate. Labrum fully exposed. Mentum with anterior depression limited by low transverse carina; surface of mentum only slightly striate. Antennae with eight antennomeres, with cupule only slightly asymmetric and rounded in outline. Maxillary palps slender, slightly shorter than width of head (Fig. 32C ). Pronotum evenly convex. Elytra without sutural or other distinct striae, with outer margins slightly flared; elytral ground punctation shallow to moderate, uniformly distributed (Fig. 32 ). Surface of prosternum flat. Mesoventrite with transverse ridge, usually elevated medially into acute tooth (Fig. 32C ); anapleural sutures concave, separated at anterior margin by distance nearly as width of anterior margin of mesepisternum. Metaventrite uniformly covered by hydrofuge pubescence, with small, longitudinal posteromesal glabrous patch, and reduced posterolateral glabrous patches (Fig. 32C ). Protibiae with spines of anterior row long, thick, semi erect and sparse; apical spurs of protibiae short and of moderate thickness. Metafemora with moderate tibial grooves; hydrofuge pubescence covering basal 4/5 of anterior surface (Fig. 32C ). Tarsomeres 1-4 ventrally with rows of long and thick setae. Metatarsomeres 2-4 gradually decreasing in size, 5 nearly as long as 2-4 combined. Fifth abdominal ventrite with small truncation at apex, with fringe of flat and stout setae. Aedeagus trilobed (Fig. 30J ); with short basal piece, less than 1/3 length of parameres; median lobe wider than width of parameres; gonopore well differentiated.

Differential diagnosis.

Globulosis is among the smallest acidocerines. Its small size along with very round and convex body shape, sets it apart from all other acidocerines known to date.

Distribution.

Neotropical: Brazil (Amazonas, Pará), Colombia, Guyana, Suriname, Venezuela; Fig. 5 .

Natural history.

The genus is most commonly found along the margins of small, sandy forested streams, especially with vegetated margins. However, a few specimens have been taken in shallow swamps.

Larvae.

The immature stages of Globulosis remain unknown.

Taxonomic history.

García (2001) described the genus with one species, and placed it in its own tribe ( Globulosina , now synonymized with Acidocerinae ). The genus was revised in 2017 by Short et al., who described one new species and examined new material that greatly expanded the range of the previously known species.

Remarks.

There are two described species of Globulosis . One female specimen from Colombia has been left unidentified as it could not be reliably assigned to any species. Because of the extremely uniform external morphology in the genus, the male genitalia is the most reliable feature for species recognition. Based on additional material we have examined the genus appears to be more broadly distributed in the Amazon region than as currently published.

Species examined.

The holotype, along with several additional specimens of Globulosis hemisphericus García, and the holotype and paratypes of G. flavus Short, García & Girón were examined in this study.

Selected references.

García 2001: genus description, monotypic; Short et al. 2017: description of one new species from Venezuela, range expansion for type species; Short et al. 2021: phylogenetic placement.

Figures

Figure 1. Variation across Acidocerinae, dorsal and lateral views A Colossochares ellipticus B Peltochares sp. C Peltochares conspicuus D Aulonochares tubulus E Helochares sp. F Helochares tristis G Novochares sp. H Helopeltarium ferrugineum I Batochares sp. J Helobata larvalis K Radicitus sp. L Nanosaphes tricolor M Agraphydrus cf. attenuatus N Tobochares luteomargo O Tobochares sulcatus P Quadriops similaris Q Crucisternum ouboteri R Primocerus neutrum S Agraphydrus coomani T Agraphydrus sp. U Globulosis flavus V Crephelochares nitescens.

Figure 2. Phylogeny of the Acidocerinae simplified from Short et al. (2021), indicating the distribution, preferred habitat, and currently described number of species for each genus. For habitat, filled black circles indicate that at least some species of the genus are commonly found in this habitat; light grey circles indicate the genus has been found in this habitat, but is rare or not typical for the group; white circles indicate no species have been recorded for the genus in this habitat.

Figure 5. Known distribution of genera of Acidocerinae: Crucisternum, Ephydrolithus, Globulosis, Helobata, Helochares, Helopeltarium, Katasophistes, and Nanosaphes.

Figure 30. Aedeagi of Crucisternum, Ephydrolithus, and Globulosis spp. A C. ouboteri B C. toboganensis C C. sinuatus D C. vanessae E C. queneyi F E. teli G E. spiculatus H E. ogmos I E. minor J G. flavus. Scale bars: 0.25 mm.

Figure 32. Habitus of Globulosis flavus A dorsal habitus B lateral habitus C ventral habitus. Scale bar: 1 mm.