Ugandaltica gen. n., a tiny flea beetle from the forest canopy in Central Africa (Coleoptera, Chrysomelidae, Galerucinae, Alticini)

Abstract In this contribution, Ugandaltica wagneri gen. n. and sp. n., collected from the canopies in the Budongo Forest, Uganda, is described. Similarities and affinities with other small-sized and convex-shaped flea beetle genera, occurring in the Afrotropical region, are discussed. Micrographs of diagnostic characters, including male and female genitalia, are supplied. Finally, some considerations on the ecology of canopy flea beetles are also reported.


Introduction
Alticini are a tribe of small to medium sized Coleoptera in the family Chrysomelidae, subfamily Galerucinae, along with the closely related Galerucini (Bouchard et al. 2011). They are named 'flea beetles' because of the presence of a metafemoral extensor tendon that enables them to jump (Furth andSuzuki 1998, Nadein andBetz 2016). Alticini are probably the largest and most diverse tribe of Chrysomelidae, comprising about 600 genera and 8000 species (Nadein 2012, Nadein and Beždek 2014, Insektoid.Info 2017. Some genera are widespread in more than one zoogeographical region, i.e. Altica Geoffroy, Aphthona Chevrolat, Chaetocnema Stephens, Longitarsus Berthold, etc., while others are strictly endemic to very limited areas . Flea beetles feed on stems, leaves or roots, and rarely flowers, both in the adult and larval stages. Host plants are known from almost all the vascular plant families, generally with high levels of specialization and close relation with the vegetation types (Jolivet and Verma 2002; Biondi andD'Alessandro 2008, Biondi et al. 2015). There is a higher species richness of flea beetles in the tropics of the southern hemisphere, even though our knowledge about this tribe is still incomplete for many of these areas (Biondi and D'Alessandro 2010a, Nadein and Beždek 2014. Based on our current knowledge, the whole Afrotropical region, including Madagascar, hosts about 1600 known species, ascribed to 101 different genera (Biondi and D'Alessandro 2010a, 2010b, 2013a, 2013b, 2016, 2017, 2018, Döberl 2010, D'Alessandro et al. 2014, 2016, 2017; and sub-Saharan Africa, in particular, hosts 85 flea beetle genera of which about 65% are endemic (Biondi and D'Alessandro 2010a, Biondi 2017. One of the most interesting, but still poorly and/or methodologically incorrectly investigated habitats is the forest canopy (Wagner 2000, Basset et al. 2003a, 2003b, Furth et al. 2003, Charles and Basset 2005, Davis et al. 2011. Studies on the arthropod composition of the forest canopies in sub-Saharan Africa have revealed a high proportion of Alticini when compared to other beetles (Wagner 2001).
In this contribution the small flea beetle, Ugandaltica wagneri gen. n. and sp. n., is described from Budongo Forest, a seasonal rain forest in Western Uganda. The similarities and affinities of this new genus with other small, convexly shaped flea beetle genera are discussed. In addition, some considerations on the ecology of canopy flea beetles are reported.

Materials and methods
Material examined consisted of dried pinned specimens, collected by fogging trees during the research activities for the Budongo Forest Project (Wagner 2000, 2001, Budongo Conservation Field Station 2017. Specimens were examined, measured, and dissected using a Leica M205C binocular microscope. Photomicrographs were taken using a Leica DFC500 camera and Zerene Stacker software version 1.04. Scanning electron micrographs were taken using a Hitachi TM-1000 scanning electron microscope. Males and females were measured to determine the mean, standard deviation and range of some morphometric measurements for each sex. The terminology follows D'Alessandro et al. (2016 fig. 10E) for the median lobe of the aedeagus, Döberl (1986), Suzuki (1988), and Furth and Suzuki (1994) for the spermatheca, and Furth (1982), Furth andSuzuki (1998), andNadein andBetz (2016) for the metafemoral extensor tendon. Geographical coordinates for localities are reported in DDM format; information included in square brackets has been added by the authors. Lines on the same label are separated by "/" and labels on the same specimen are separated by "//". Chorotypes follow Biondi and D'Alessandro (2006). Abbreviations of ecological data, referring to fogged trees and the type of forest, as recorded on the original labels; by courtesy of Thomas Wagner:

Taxonomic part
Ugandaltica gen. n. http://zoobank.org/3118EF6B-DA2C-4F3D-AB9F-BABED77FCC33 Diagnosis. The very small size, convex body, and rather short antennae (Fig. 1A) make the new genus similar to the "moss-inhabiting genera", mainly widespread in the Palaearctic and Oriental Regions (Konstantinov et al. 2013, Damaška and Konstantinov 2016, Ruan et al. 2017). This habitus is, therefore, a clear example of adaptive convergence. The diagnostic characters of the "moss-inhabiting genera" are notably different The genus Stegnaspea is immediately distinguishable from Ugandaltica gen. n. by the lack of a scutellum, along with several other characters, concerning among others the head sculpture, shape of the maxillary palpi, shape of the pronotum and pronotal sculpture, elytral surface, male and female genitalia, and the metafemoral extensor tendon ).
The genus Jacobyana shows some similarities with the new genus in its pronotal shape and sculpture, first two antennomeres, and the metafemoral extensor tendon (Biondi and D'Alessandro 2011). However, it is easily distinguishable from this genus by the shape and sculpture of the head, shape of the distal antennomeres, anterior angles of the pronotum, third and fourth visible tarsomeres, and the rather different male and female genitalia.
Bezdekaltica, a genus known only from the species B. socotrana Döberl, shares along with its general shape (Döberl 2012) some aedeagal characteristics with Ugandaltica gen. n., such as the absence of sculpture, the presence of rather big pores on the surface, and the peculiar shape of the phallobasis (Figs 3C, 4C). Notwithstanding these similarities in the aedeagus, considered a likely indicator of real affinity, differences in the female genitalia (Figs 3D, 4D), head and pronotal sculpture, the shape of antennomeres, palpi, prosternum, and the tarsi (Döberl 2012), allow us to consider Ugandaltica gen. n. as a different genus. Bezdekaltica specifically differs from Ugandaltica gen. n. in having: deeply incised frontal grooves which connect in the middle of the frons (Fig. 4A); an anteriorly and posteriorly bordered pronotum, with short longitudinal lateral impressions touching pronotal base (Fig. 4A); sharp maxillary palpi (Fig. 4B); the third tarsomere larger than the second, and slender fourth visible tarsomeres; antennomeres which are clearly more homogenous in shape; and the prosternum wider anteriorly than the intercoxal prothoracic process (Fig. 4B). In addition, Bezdekaltica has closed procoxal cavities, this is contrary to the statement reported by Döberl (2012), which also separates it from Ugandaltica gen. n. (Fig. 4B).
Description. The new genus is established on the following set of characters. Body roundish, clearly convex, glabrous (Fig. 1A). Frons and vertex smooth; frontal tubercles absent; frontal grooves distinctly impressed, extending from upper ocular margin to antennal socket on each side; genae moderately elongate; maxillary palpi four-segmented, thickset; labial palpi three-segmented ( Fig. 2A, C). Antennae slightly shorter than half the body length (Fig. 1A); antennomeres 1-2 distinctly larger than the rest; antennomere 7 distinctly larger than adjacent antennomeres ( Fig. 2A). Pronotum sub-trapezoidal, slightly wider posteriorly, distinctly transverse, and distinctly rounded laterally, as wide as elytral base basally; anterior and basal margin not bordered; basal margin distinctly sinuous; lateral margin moderately expanded; anterior angles distinct and prominent, obliquely bevelled; posterior angles with a slightly prominent setigerous pore; punctation clearly impressed (Fig. 2B). Scutellum slightly elongate, roundish apically (Fig. 2B). Elytra indistinctly elongate, entirely covering pygidium, strongly arcuate laterally, jointly rounded apically; lateral margin moderately expanded up to subapical part of elytra, slightly visible in dorsal view; punctation arranged in 9 (+ 1 scutellar) regular rows, distinctly impressed but becoming shallower towards the elytral apex; humeral callus distinctly prominent; elytral epipleurae horizontally orientated, slightly visible laterally up to apical fourth of elytra (Figs 1A, 2D). Macropterous metathoracic wings. Hind femora clearly swollen; tibiae straight, not channeled, external margin not dentate; apical spur only present on hind tibiae, simple, and moderately elongate; third tarsomere of all legs about as narrow as second; ungual tarsomere of all legs slightly enlarged; and tarsal claws sub-appendiculate (Figs 2D, 3A). Prosternum clearly narrower anteriorly than intercoxal prothoracic process; and procoxal cavities open (Fig. 2C). Metafemoral extensor tendon with extended arm of dorsal lobe moderately elongate and slightly depressed; basal angle of ventral lobe acute; dorsal margin of ventral lobe straight, distinctly oblique; recurved flange distinctly sclerotized; dorsal-basal angle of the tendon almost right angled; ventral-basal angle of tendon widely obtuse; basal edge of tendon slightly curved (Fig. 3B). The metafemoral extensor tendon of this new genus is similar to those of the Psylliodes morpho-group (Furth and Suzuki 1998), but most likely constitutes a new morpho-group, which will include Jacobyana. Aedeagal surface without any complex sculpture, but with evident pores; phallobasis widely rounded basally; aedeagus distinctly curved in lateral view (Fig. 3C). Spermatheca of the "alticine type" (Type A of Furth and Suzuki 1994), with distal part distinct from basal part, ductus uncoiled, laterally inserted, and not invaginated in the basal part; neck not distinctly separate from basal part; apical part thicker than neck and distinctly separate (Fig. 3D). Tignum and vaginal palpi as in Fig. 3D.
Etymology. This new genus is named after Uganda, the country in which it was collected. Female gender.
Variations. Paratypes are very similar in size, shape, sculpture and colour to the holotype. Female without the dilated first tarsomere in the anterior and middle tarsi. Spermatheca ( Fig. 3D) with sub-cylindrical basal part, narrower towards distal part; neck not distinctly separated from basal part; apical part thicker than neck and distinctly separated from it; ductus thin, as long as half the length of basal part, uncoiled, and laterally inserted.
Male ( Etymology. The specific epithet is a Latinized noun in the genitive case referring to its collector Thomas Wagner (University of Koblenz-Landau, Germany), renowned specialist of Afrotropical Galerucini.
Distribution. Central Africa (Uganda). Considering both the habitat types and the most common species distributions associated with each chorotype (Biondi and D'Alessandro 2006), Ugandaltica wagneri sp. n. possibly falls inside the Northern-Eastern Afrotropical chorotype (NEA).

Discussion
The general similarities of the new taxon, here described, with those of the "moss-inhabiting genera" seem incidental, and is not due to similar habitat occupancy. In addition, being macropterous is indicative that Ugandaltica gen. n. can move easily, a characteristic not found in moss-inhabiting flea beetles (Konstantinov et al. 2013, Damaška and Konstantinov 2016, Ruan et al. 2017. Ugandaltica wagneri sp. n. was collected by fogging trees in primary and secondary tropical forest formations (Wagner 1999(Wagner , 2000(Wagner , 2001. Wagner (1999Wagner ( , 2001 found that the flea beetle abundance significantly increased in both the primary and the secondary forest during the dry season. The canopies of trees with dense foliage are often the most humid habitats, and small, soft-bodied insects in particular presumably accumulate along a gradient of humidity. Moreover, there is evidence that the abundance of phytophagous insects peaked during leaf flush periods, which happen during the late dry season at the end of January. This is because of their preference for young leaves, and because herbaceous food plants are often no longer available (Wagner 2001). However, Alticini seemed not to feed on trees, as gut dissection of the most abundant species revealed, but rather fed on plants in the surrounding habitat (Wagner 1999). It is interesting that Ugandaltica wagneri sp. n. was one of the few flea beetle species also present in the canopy during the wet season. Because of the poor conservation status, and the very small size of the specimens, we preferred not to dissect their gut to investigate whether they were feeding on tree foliage. If they used the canopy as refugium habitat only, then they would only exploit their real host plant during a limited period of the year.

Conclusions
Most studies on the arthropod composition of the canopy have dealt with several different taxa, which is why a morphospecies approach has often been chosen. This implies that the collected specimens often required further taxonomic investigation by a specialist for their determination. In this paper a new genus and species from a tropical forest in Western Uganda are described, providing a contribution to the knowledge of the flea beetle fauna from canopies of Afrotropical forests. Alticini seem to be one of the more representative taxa of the canopy of tropical forests (Basset and Samuelson 1996, Wagner 1999, 2001, Furth 2003, Charles and Basset 2005. However, because of the dynamics of the canopy faunal composition, the correct interpretation of their presence needs more insight on the ecology and biology of the species found there. For this rea-son, it will be fundamental to understand how they are distributed in the forest habitat as a whole, and not only in canopy habitats (Basset et al. 2003a). In this regard it must be said that further research in forest habitats might reveal that Ugandaltica wagneri sp. n. is more closely associated with a specific forest layer, considering the small number of known specimens and the confined habitat from which they were collected.