Brachyauchenus Brunner von Wattenwyl, 1895

Cadena-Castañeda, Oscar J., Rodríguez, Nixon Oscar Parra, Res, Gustavo Costa Tava-, Rodríguez, Diana Marcela Trujillo & Arias, Ronald Fernando Quintana, 2021, Studies on Neotropical Pseudophyllinae: The status of the genus Brachyauchenus Brunner von Wattenwyl, 1895 and its species (Orthoptera: Tettigoniidae: Pseudophyllinae: Platyphyllini), Zootaxa 5027 (4), pp. 546-562 : 548-549

Brachyauchenus Brunner von Wattenwyl, 1895

http://lsid.speciesfile.org/urn:lsid: Orthoptera .speciesfile.org:TaxonName:5032

New diagnosis. Body mid-sized (30–40 mm) and robust, the only known species reddish-brown ( Figs. 1 , 4 ). Pronotum very granulated, with lateral lobes projecting laterally in dorsal view ( Figs. 1B , 4B ); meso- and metazonal groove deep and joining at the lateral lobes, forming a delimited region from the rest of the pronotum ( Figs. 1A, 1B , 4A, 4B ). Brachypterous, wings not covering the last two or three abdominal segments in males ( Fig. 1A ) and the last four in females ( Fig. 4A ). Legs slender and moderately elongated, conspicuously ridged on both outer and inner sides, all femora dorsally unarmed and only the hind tibia bears dorsal spines; fore coxae armed with a conspicuous dorsal spine, ventrally with two tubercles, one at the middle and other at the apex; mid and hind coxae unarmed. Sternum typical of the tribe Platyphyllini regarding the organization of furrows. Tenth tergite, epiproct, and male cerci without conspicuous projections nor ornaments ( Figs. 2D, 2G ). Styli notably elongated, as long as the subgenital plate ( Figs. 2E, 2F ). Ovipositor robust, slightly longer than the hind femur ( Figs. 5A, 5B ), female subgenital plate undivided ( Fig. 5C ).

Type species. Brachyauchenus castaneus Brunner von Wattenwyl, 1895 . Herein, the genus is regarded as monotypic. The other species that until now were included in this genus are being moved to other genera.

Comparison. In Beier’s key (1960), Brachyauchenus is more akin to Aemasia Brunner von Wattenwyl, 1895 , due to the lateral lobes expanded to the sides in dorsal view, although Aemasia is more similar to Diyllus Stål, 1875 . In the current featuring of the genus (only including B. castaneus ), Brachyauchenus is more similar to Triencentrus , and the following characters differentiate both genera: Brachyauchenus has a reddish-brown or dark brown coloration (the only species included with the costal area of the tegmina with yellowish stripes outlined in black), in contrast, the Triencentrus species are light brown or yellowish-brown. The spines on the ventral margin of the femora and the dorsal margin of the hind tibia are thicker and more conspicuous in Brachyauchenus than in Triencentrus . Both genera have similar cerci structures (cylindrical and armed by a small inward spine at the apex), although some species of Triencentrus bifurcate close to the apex (e.g., Triencentrus bilobatus Beier, 1960 ). Regarding the subgenital plate of males, there are no modifications of the common shape. However, in Brachyauchenus the styli are conspicuously long, as long as the subgenital plate. On the other hand, in Triencentrus the styli are half long or at most three-quarters of the subgenital plate.

Comments. The nominal species B. castaneus significantly differs morphologically from the other species currently included in the genus, making it necessary to allocate B. minutus and B. festae into a new genus and to move B. varicosus to Stenoschema Redtenbacher, 1895 . With these nomenclatural acts, Brachyachenus becomes monotypic. It was necessary to provide a new diagnosis for the genus once the diagnoses proposed in the original description ( Brunner von Wattenwyl, 1895) and by Beier (1960) were adjusted to the species allocated within the genus at each moment. Previously, the characters were general and could coincide with species of Triencentrus , Xiphophyllum , and Baliophyllum Beier, 1962 . However, Brachyauchenus is easily distinguished from these two last genera by the brachypterous condition.

Figures

FIGURE 1. Brachyauchenus castaneus Brunner von Wattenwyl, 1895. Male habitus. A. Lateral, B. Dorsal, and C. Frontal views.

FIGURE 2. Brachyauchenus castaneus Brunner von Wattenwyl, 1895. Stridulatory apparatus in dorsal view of A. Left-wing and B. Right-wing. C. Left stridulatory file. Male terminalia in D. Dorsal, E. Ventral, F. Lateral, and G. Axial views.

FIGURE 4. Brachyauchenus castaneus Brunner von Wattenwyl, 1895. Female habitus. A. Lateral, B. Dorsal, and C. Frontal views.

FIGURE 5. Brachyauchenus castaneus Brunner von Wattenwyl, 1895. Female terminalia in A. Dorsal, B. Lateral, and C. Ventral views.