Arulenus Stål, 1877

Skejo, Josip & Caballero, Joy Honezza S., 2016, A hidden pygmy devil from the Philippines: Arulenus miae sp. nov. — a new species serendipitously discovered in an amateur Facebook post (Tetrigidae: Discotettiginae), Zootaxa 4067 (3), pp. 383-393 : 385

Genus Arulenus Stål, 1877

Type species: Arulenus validispinus Stål, 1877 by subsequent monotypy.

The genus Arulenus was erected by Stål in 1877 for A. validispinus and A. punctatus (now Hirrius punctatus ), both described in the same paper, together with the genus. Bolívar (1887) erected the genus Hirrius for H. punctatus ( Stål, 1877) and has left only A. validispinus within Arulenus . In the Orthoptera Species File ( Eades et al. 2015), A. validispinus is noted to be the type species of the genus Arulenus by the original monotypy, which is not correct. The species is the type species of the genus by subsequent monotypy, after the separation of the genus Hirrius from Arulenus . Thus, the genus became monotypic since Bolívar (1887) and now we add one more species to the genus.

Diagnosis of the genus. The genus can be easily distinguished from similar genera by the following characters: a single paranotal lobe present, tegmina and alae absent, lateral paranotal lobes turned outwards, pronotum surface smooth, slightly wrinkled, high spines present on pronotal discus.

Comparative notes. The genus is similar to following genera: of Discotettiginae Discotettix Costa, 1864 , Hirrius punctatus group and Hirrius montanus group. It can be separated from Discotettix by the shape of paranota, absence of wings, pronotum that is not wrinkled and not tuberculated, and smooth femora surface. From Discotettix shelfordi , it can be distinguished by the absence of wings, morphology of paranota, the presence of strong spines on pronotal discus, and smooth femora. From Hirrius punctatus group ( H. punctatus , H. scrobiculatus , H. mindanaensis ), it can be separated by the presence of strong pronotal spines. From Hirrius montanus group ( H. montanus , H. sarasinorum , Hirrius sp.) it can be separated by the absence of wings, non-granulated body and femora, and the presence of concave internal lateral carina of pronotum. Among non-Discotettiginae genera, the genus is morphologically similar to Tondanotettix Willemse, 1928 (OSF currently places this in Cladonotinae , but is likely a member of Scelimeninae ), from which it can be separated primarily in the presence of widened antennal segments, narrower interscapular area, and the presence of strong spines on pronotal discus.

Genera with appearance similar to Arulenus: Malagassy and Oriental fauna. One cannot overlook the obvious similarity of pronotal morphology of A. miae sp. nov. and specimens from Malagassy genera Eurybiades , Notocerus and Holocerus , as well as Borneo genus Hexocera . This is a very good example of convergent evolution of a few evolutionary independent genera. In Arulenus ( A. validispinus Stål and A. miae sp. nov.) pronotal spines are only excrescence of the interhumeral carinae (situated between carina medialis and carina lateralis), while in Notocerus and Holocerus these acuminate processes are actually elevations of humeral carinae. These genera are in fact members of separate subfamilies— Arulenus of hitherto valid Discotettiginae, Notocerus and Holocerus of Metrodorinae , Hexocera of Scelimeninae . It has been pointed, however, that Metrodorinae may not be a monophyletic group (Pavón-Gonzalo et al. 2012) and this subfamily is in need of a comprehensive revision. The monotypic genus Hexocera from Borneo, is related to Scelimena and other Scelimeninae genera with the widened basitarsal segment of the hind legs. All these genera developed similar morphological traits, probably as an adaptation to deter predators. Two genera with similar general appearance to Arulenus are shown on Figure 2 .

Figures

FIGURE 2. Genera with general appearance similar to Arulenus: Holocerus taurus from Madagascar (A nymph, B adult), and Hexocera hexodon from Borneo (C). (A—photo: Frank Vassen, B, C—photo Paul Bertner, reproduced with permission).