Acidocerus
| Notice: | This page is derived from the original publication listed below, whose author(s) should always be credited. Further contributors may edit and improve the content of this page and, consequently, need to be credited as well (see page history). Any assessment of factual correctness requires a careful review of the original article as well as of subsequent contributions.
If you are uncertain whether your planned contribution is correct or not, we suggest that you use the associated discussion page instead of editing the page directly. This page should be cited as follows (rationale):
Citation formats to copy and paste
BibTeX: @article{Girón2021ZooKeys1045, RIS/ Endnote: TY - JOUR Wikipedia/ Citizendium: <ref name="Girón2021ZooKeys1045">{{Citation See also the citation download page at the journal. |
Ordo: Coleoptera
Familia: Hydrophilidae
Name
Acidocerus Klug, 1855 – Wikispecies link – Pensoft Profile
- Acidocerus Klug, 1855: 649.
Gender
Masculine.
Type species
Acidocerus aphodioides Klug, 1855: 649; by monotypy.
Diagnosis
Small beetles, body length nearly 2.8 mm. Body shape elongate oval in dorsal view, moderately convex in lateral view, with dorsal outline nearly straight along anterior 2/3 of elytra (Fig. 17). Surface of head and pronotum granulate (Fig. 17C). Body pale/yellowish brown, with head slightly darker. Eyes with anterior margin straight in lateral view (not emarginate), in dorsal view slightly projecting from outline of head (Fig. 17C). Labrum not concealed by clypeus (Fig. 17C). Antennae with nine antennomeres, with strongly asymmetric cupule, with longer side acute. Maxillary palps elongate, with palpomere 4 nearly as long as palpomere 3 (d’Orchymont 1943f[1]: 7, in key). Elytra without sutural striae, narrowly explanate laterally, serial punctures strongly marked, arranged in rows (Fig. 17A). Prosternum flat, rather sharply carinate medially, with angulate anteromedian projection. Posterior elevation of mesoventrite only weakly bulging. Metaventrite with hydrofuge pubescence. Metafemora without distinct tibial grooves, mostly pubescent, only glabrous at apex. Metatarsomeres 1–4 similar in length; metatarsomere 5 similar in length to metatarsomeres 1–4 combined. Fifth abdominal ventrite apically emarginate, with stout setae.
Differential diagnosis
The long fifth metatarsomere (longer than metatarsomeres 1–4 combined) is unusual but not unique in the subfamily (Hansen 1991[2]). The granulate surface of the head and body resembles that of Helobata, but besides their geographic origin, the exposed labrum of Acidocerus (as opposed to concealed in Helobata) allows its recognition. The small size and coarse punctation of the elytra of Acidocerus resemble some of the Old World Helochares (e.g., Fig. 36D–F) and some Agraphydrus (e.g., Agraphydrus hanseni, Fig. 19A), from which it can be differentiated by the medially sharply carinate prosternum (Hansen 1991[2]).
Distribution
Afrotropical: Mozambique; Fig. 4.
Natural history
There is no natural history information available for the genus.
Larvae
Immature stages are not known for the genus.
Taxonomic history
The taxon was originally described as related to Spercheus Kugelann, with maxillary palps similar to those of Hydraena Kugelann (Klug 1855[3]), and even later afforded its own subfamily (see taxonomic history of the Acidocerinae section, above). d’Orchymont (1943f[1]: 7) provided a list of diagnostic characters in a key, including the relative length of its tarsal segments, specifically that the fifth tarsomere is as long as tarsomeres 1–4 combined. Hansen (1991)[2] redescribed the taxon based on syntypes. Hansen (1991[2]: 149) further commented that he had seen other “typical” species of Helochares that also shared this feature and stated that “although Acidocerus may be somewhat reminiscent of a small Helochares… I prefer to maintain it as a distinct genus at the present stage”. The genus was not included in the molecular phylogeny in Short et al. (2021)[4], and its assignment to the Helochares group is based primarily on its overall dorsal sculpturing, lack of a sutural stria, and Afrotropical distribution.
Remarks
Only one described species. Hansen (1991)[2] studied Klug’s syntypes housed at the Museum für Naturkunde der Humboldt-Universität in Berlin, Germany (ZMHB), which are the only known specimens for the genus. The diagnostic features listed above include information from d’Orchymont (1943f)[1], Hansen (1991)[2], and our own observations of photographs of the syntypes. Given that the specimens were mounted on cards when photographed, features of the ventral surface were not viewed by us. Characters of the ventral features (as well as the maxillary palps) as described above are based on d’Orchymont (1943f)[1] and Hansen (1991)[2], as the maxillary palps appeared to be missing by the time Hansen examined the syntypes. Until additional specimens are found, it is unlikely there will be a satisfactory resolution on deciding if Acidocerus is in fact a distinct genus or rather another variant of Helochares.
Species examined
Acidocerus aphodioides (photographs of syntypes).
Selected references
Klug 1855[3]: 649: original description; d’Orchymont 1943f[1]: 7: offers diagnostic features in a key; Hansen 1991[2]: 149: redescription; Short and Fikáček 2013[5]: 741: Acidocerus listed in subfamily Acidocerinae; Short et al. 2021[4]: phylogenetic position and affinities discussed.
Taxon Treatment
- Girón, J; Short, A; 2021: The Acidocerinae (Coleoptera, Hydrophilidae): taxonomy, classification, and catalog of species ZooKeys, 1045: 1-236. doi
Images
|
![Figure 2. Phylogeny of the Acidocerinae simplified from Short et al. (2021)[4], 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.](/wiki/File:Zookeys-1045-001-g002.jpg)
![Figure 19. Habitus of Agraphydrus spp. AA. hanseniBA. jilanzhuiCA. longipalpusDA. contractusEA. anhuianusFA. puzhelongi. Images B–F from Komarek and Hebauer (2018)[6]. Scale bars: 1 mm.](/wiki/File:Zookeys-1045-001-g019.jpg)
Other References
- ↑ 1.0 1.1 1.2 1.3 1.4 d’Orchymont A (1943f) Palpicornia (Coleoptera) VI.Bulletin du Musée royal d’histoire naturelle de Belgique19(60): 1–12.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Hansen M (1991) The hydrophiloid beetles. Phylogeny, classification and a revision of the genera (Coleoptera: Hydrophilidae).Biologiske Skrifter40: 1–367.
- ↑ 3.0 3.1 Klug J (1855) (Diagnosen neuer Coleoptera aus Mossambique).Bericht über die zur Bekanntmachung geeigneten Verhandlungen der Konigl Preuss Akademie der Wissenschaften zu Berlin1855: 643–660. https://biodiversitylibrary.org/page/11070837
- ↑ 4.0 4.1 4.2 Short A, Girón J, Toussaint E (2021) Evolution and biogeography of acidocerine water scavenger beetles (Coleoptera: Hydrophilidae) shaped by Gondwanan vicariance and Cenozoic isolation of South America.Systematic Entomology46(2): 380–395. https://doi.org/10.1111/syen.12467
- ↑ Short A, Fikáček M (2013) Molecular phylogeny, evolution and classification of the Hydrophilidae (Coleoptera).Systematic Entomology38(4): 723–752. https://doi.org/10.1111/syen.12024
- ↑ Komarek A, Hebauer F (2018) Taxonomic revision of Agraphydrus Régimbart, 1903 I. China and Taiwan (Coleoptera: Hydrophilidae: Acidocerinae).Zootaxa4452(1): 1–101. https://doi.org/10.11646/zootaxa.4452.1.1
