Haroldius, Boucomont, 1914

Krell, Frank & Philips, T., 2010, Formicdubius Philips & Scholtz from South Africa, a junior synonym of Haroldius Boucomont, and a survey of the trichomes in the African species (Coleoptera, Scarabaeidae, Onthophagini), ZooKeys 34 (34), pp. 41-48 : 42-46

African Haroldius species

All African species of Haroldius appear to have trichomes on the mesepimeron, the pronotal base, and the elytral base. Trichomes appear as distinct and relatively tight clusters of setae while others are looser or even single rows of thick setae such as those on the elytral base. Without microsections we are unable to decide whether those might be proper trichomes associated with glands or mechanoreceptors. However, as further evidence of a glandular association, longitudinal grooves at the pronotal base are also present that may facilitate the spreading of allomone secretions onto the pronotal surface, increasing the attractiveness of these beetles to their host ants.

Formicdubius convexus (Figs 1–6) (and the very similar or conspecific Haroldius leleupi Janssens, 1953 ; Figs 11–13) can easily be distinguished from the remaining Haroldius species by the presence of a distinct notch between the pronotum and the elytral base accommodating the pronotal trichomes (Figs 2, 12). In Haroldius ennearthrus Janssens, 1949 (Figs 14–19), the basal margins of pronotum and elytra are straight with the pronotal margin slightly emarginate close to the edge (Figs 15, 18); a notch is missing, but a slight lateral depression towards the bases of the pronotum and elytra is visible. H. modestus Janssens, 1953 shares the general shape of the pronotal and elytral bases with H. ennearthrus but the pronotal margin is slightly more strongly emarginate laterally (Figs 8–9).

Figures Ι–6. Haroldius convexus : Ι Dorsal habitus 2 Trichomes within cleft between prothorax and mesothorax and showing pronotal sulci 3 SEM (scanning electron microscope) view of pronotal trichome 4 SEM view of pronotal trichome showing possibly ant-gnawed tips of the setae 5 SEM view of possible trichomes on the elytral base 6 SEM view of trichome on the mesepisternum and additional setal row proximally.

The trichomes on these species are located on the mesepisternum anterolaterally, the elytra anterolaterally (on the vertical surface facing the pronotum), and on the pronotal base posterolaterally. One should be aware that these setae may be damaged from the effects of gnawing by their host ants and the actual number of setae may vary in number more than we report due to our limited sample sizes. Regardless, the degree of development of these structures in each species is as follows:

Specimens of H. ennearthrus possess a large rounded cluster of setae on the mesepisternum (Fig. 19) and no additional setae proximally. They also appear to have two short and relatively thick setae on the elytral base. Three to five thick setae are present on the pronotum (Figs 16–18) as well as a row of similar aligned setae proximal to these, all of which may be trichomes (Fig. 16).

Haroldius modestus (Figs 7–10) also has a large, rounded cluster of setae on the mesepisternum (Fig. 10) and lacks any thick setae proximally. There are two to three thick setae on the elytral base. On the pronotum a brush-like trichome is well developed, consisting of six to sometimes ten or more, long, thick setae (Figs 8–9).

The third described Haroldius species from Africa, H. leleupi (Figs 11–13), is strikingly similar to Formicdubius convexus (Figs 1–6). They both have a small cluster of stout setae on the mesepisternum (Figs 6, 13) and proximal to this are a few more thick and elongate setae arranged in a transverse row (Fig. 6). These same setae become more slender and slightly more widely separated the further from the mesepisternal trichome. Additionally, there are four to five short, thick setae at the base of the elytra near the lateral margin (Fig. 5). Both species also have a well developed trichome on the pronotal base consisting of 20 or more lobe shaped setae (Figs 3–4, 12–13).

We are unsure whether H. leleupi and F. convexus are distinct taxa. H. leleupi is generally larger; the five specimens studied measure 1.80–2.20 mm in length (average 2.06 mm), whereas the 14 sampled types of F. convexus measure 1.63–1.90 mm (average 1.78 mm). Haroldius leleupi also has slightly stronger (more clearly defined) punctures on the disk of the pronotum and the elytral intervals and slightly deeper elytral striae, particularly near the suture. Additional material will be required from localities between the Congo and South Africa to decide to what extent these minor differences indicate taxonomic differentiation.

Synonymy

Haroldius leleupi and Formicdubius convexus are difficult to distinguish at the species level, but there is no doubt that Formicdubius is identical with Haroldius at the generic level. Formicdubius fully matches Boucomont’s (1914) original description of Haroldius . It also agrees with the extended diagnosis of Haroldius recently published by Krikken and Huijbregts (2006) with the exception that all African species currently subsumed under Haroldius possess trichomes.

Figures 7–Ι3. Haroldius species. Figures 7–Ι0. H. modestus 7 Dorsal habitus 8 Trichomes within cleft between prothorax and mesothorax and showing pronotal sulci 9 Pronotal trichome Ι0 SEM view of trichomes on the pronotum and mesepisternum. Figures ΙΙ–Ι3. Haroldius leleupi : ΙΙ Dorsal habitus Ι2 Trichomes within cleft between prothorax and mesothorax and showing pronotal sulci Ι3 SEM view of trichomes on the pronotum and mesepisternum.

We propose the following synonymy:

Haroldius Boucomont, 1914 (type species by subsequent designation by Arrow, 1931: Haroldius rugatulus Boucomont, 1914 )

= Formicdubius Philips & Scholtz, 2000 (type species by original designation: Formicdubius convexus Philips & Scholtz, 2000 ), syn. n.

Consequently, the following new combination is established:

Haroldius convexus ( Philips & Scholtz, 2000) Krell & Philips, 2010 , comb. n.

We refrain from determining the taxonomic status of the African species of the Haroldius / Afroharoldius group. All African Haroldius species have more or less distinct trichomes which could be a synapomorphy justifying a genus or subgenus Afroharoldius . However, we neither know if trichomes (vestigial or distinctive) are common in Asian Haroldius species, or whether the trichome-bearing species are the sister group of the trichome-less Haroldius , or whether their exclusion from Haroldius would leave Haroldius or Afroharoldius paraphyletic. In Haroldius brendelli Krikken & Huijbregts , antehumeral elytral trichomes are described ( Krikken and Huijbregts 2009). Based on the illustrations in Krikken and Huijbregts (2006), it appears as though pronotal grooves are present on at least some Asian species and, moreover, trichomes seem to be present in H. tangkoko Krikken & Huijbregts and H. cambeforti Krikken & Huijbregts (see their figs 5 and 6). A revision and phylogenetic analysis of the whole group, including species of Phaedotrogus Paulian and probably Ponerotrogus Silvestri and Cyclotrogus Wasmann (both currently considered to be junior synonyms of Haroldius ), will probably be necessary to establish a sound genus-level classification. Currently we see no reason to change the status of Afroharoldius as junior synonym of Haroldius .