Bioacoustics of Glomeremus pileatus

Remarks . The typical pattern of the pronotum with two dark bands in the middle of the pronotum ( Figs. 1, 2 ) and microscopic stridulatory ridges, covered by setae, along the sides of the 2nd and 3rd terga consent to ascribe them to G. pileatus . Types ( 1 male and 2 females ) came from Ra’s Shoab ( Krauss 1907 ), and according to Uvarov and Popov (1957) and Wranik (2003) it appears a rare species, known on the area of airport and Hadibou plain. The ovipositor is very thick, with an evident central furrow along its upper side ( Figs. 3, 5 ); the subgenital plate is provided with an arc-like swelling ( Figs. 4, 6 ). This species, lacking of scale-like tegmina, is possibly more related to G. capitatus Uvarov, 1957 than to G. mediopictus Uvarov, 1957 . It shares with the latter the presence of stridulatory ridges, lacking in the former; conversely, the ovipositor of G. mediopictus ( Fig. 7 ) and the general structure of the body are weaker than those of G. pileatus .

Diagnostic notes. Glomeremus pileatus ( Krauss, 1902 ) is characterised by a typical pattern of two bands in the middle of the pronotum (Figs 191 , 192 , 194 ). This pattern is quite variable (Uvarov in Uvarov and Popov (1957) ; Massa 2009 ). In some specimens, the markings are pitch black; in others, they are rufous, as mentioned for the type specimen or even faded. The same applies to other body markings like legs or abdomen. A population that may belong to G. pileatus occurs in dunes near Arher, but features little to no dark pigmentation. Contrary to what Popov (1984) stated in his key to the species of Glomeremus of Socotra , the stridulatory pegs are on the 2 nd and 3 rd tergites, not the 1 st and 2 nd . Furthermore, in G. pileatus , the head is also clearly wider than the pronotum, as depicted in, for example, figs 1–2 in Massa (2009) . The width of the head is not a good character to separate the species from G. capitatus . In comparing Popov’s material with Krauss’s description, Uvarov (in Uvarov and Popov (1957) ) noticed that the ninth tergite in the male is not convex behind, but decidedly truncated. The same is true in our material (Fig. 188 ). For further characteristics, see G. capitatus .