Acrotylus incarnatus Krauss, 1907

Massa, Bruno, 2009, New and less known Orthoptera (Insecta) from the island of Socotra (Yemen), Zootaxa 2132, pp. 53-64 : 56-57

Acrotylus incarnatus Krauss, 1907

Material examined. Socotra , Di Lisha 4.IV.2008, B.Massa (13, 1Ƥ); Hom Hil 5.IV.2008, B.Massa (13); Qalansiyah river (Shata) 6.IV.2008, B.Massa (13, 2Ƥ); Ra’s Shoab 6.IV.2008, B.Massa (23, 1Ƥ); Tenten 7.IV.2008, B.Massa (13, 1Ƥ); Zam Hom 8.IV.2008, B.Massa (13, 2Ƥ); Wadi Ayev 10.IV.2008, B.Massa (1Ƥ), 20.II.2009, P.Lo Cascio & F.Griti (13, 1Ƥ); Wadi Da’arho 21.II.2009, P.Lo Cascio & F.Griti (23); Detwa Lagoon 26.II.2009, P.Lo Cascio & F.Griti (2Ƥ).

Remarks. Krauss (1907) described Acrotylus longipes var. incarnata from Socotra for its rose-coloured wings (“ Differt a forma typica alis basi dilute incarnatis ”). Uvarov and Popov (1957) pointed out that all the specimens from Socotra have rose-coloured wings, but do not differ morphologically from the East African A. longipes var. meruensis Sjöstedt, 1932 , in which wings are either rose or yellow. Because of the larger and heavier body of Mediterranean A. longipes (Charpentier, 1845) , compared to Socotra specimens, they proposed to consider A. incarnatus specifically distinct. Thus, A. longipes var. meruensis should be synonym of A. incarnatus , raised to valid species, and consequently distributed on Socotra , as well as on East Africa.

It is well known that A. longipes is characterized by its very long mid femora, mainly when they are compared with the width of tegmina. Also the ratio mid/fore femora permits to separate easily A. longipes from species with shorter and stout mid femora, such as A. patruelis (Herrich-Schäffer, 1838) , A. insubricus (Scopoli, 1786) and A. fischeri Azam, 1901 (ratio in males between 1.3 and 1.5, in females between 1.3 and 1.6). Although I found statistical differences between these species and A.longipes / incarnatus , I failed to find any significant difference (test t of Student) between A. incarnatus and A. longipes from Sicily (type locality). Concerning the size of A. incarnatus and A. longipes , I measured the body length of both species (Table 1). While between males differences did not result significant, between females they were statistically significant (test t of Student, P<0.01, f.d.: 38), which means that on average the female of A. longipes is smaller than the female of A. incarnatus . This is the opposite of what Uvarov and Popov (1957) wrote. However, I measured a series of A. longipes var. meruensis from Somalia, preserved in the Museo Civico di Storia Naturale of Milan, labelled as A. incarnatus (det. M. La Greca), as well as A. longipes var. meruensis (det. V.M. Dirsh) (Table 1); differences between the ratio mid/fore femurs of A. longipes meruensis from Somalia and A. incarnatus from Socotra resulted highly significant for both sexes (test t of Student, P<0.001, f.d.: 28 and 32, respectively), between the body length of males resulted not significant, while between females resulted statistically significant (P = 0.006, f.d.: 32).

According to Ingrisch (1999), the keel in the prozona of the pronotum of A. longipes is absent and the principal sulcus is slight sinuate, weak in middle, other sulci are absent in the prozona. As shown in Figs. 8, 11 and 14 , the keel in the prozona of A. longipes is actually weak, while in A. incarnatus it is very weak, almost absent ( Figs. 10, 13, 16 ); further, A. incarnatus and A. longipes may show a second inappreciable sulcus in the prozona ( Figs. 8, 9 ). Concerning A. longipes meruensis , its pronotum, in lateral view, has a different profile from the other two species, and seen from above it shows the presence of a small keel in the prozona; its principle sulcus is strongly sinuate and distinct in middle, similar to that of A. blondeli Saussure, 1884 ( Ingrisch 1999) , differing from the former for other characters. Additionally, as reported above, the former has shorter mid femurs than Socotran A. incarnatus and Sicilian A. longipes . The ratio between the prozona and metazona of the pronotum is another character which consents to separate at least two of the three species; in A. incarnatus the metazona is between 1.6 and 1.8, while in A. longipes it is between 1.3 and 1.5 and in A. meruensis between 1.7 and 1.9 longer than prozona ( Figs. 11-16 ). The pronotum profile of A. incarnatus is more evidently excised on the lateral lobes and more elongated backwards ( Figs. 9, 10 ). Thus, we may consider A. incarnatus a distinct species from A. longipes , but also from the East African A. longipes meruensis , which could be raised to valid species, clearly distinct from them.

Finally, it seems that A. incarnatus is present only on Socotra and that in Somalia and possibly in East Africa another species occurs, A. meruensis , till now considered as a synonym of A. incarnatus ( Eades & Otte 2008) .

Figures

FIGURES 8 – 16. Acrotylus. Lateral and view from above of A. longipes from Sicily (8, 11, 14), A. meruensis from Somalia (9, 12, 15) and A. incarnatus from Socotra (10, 13, 16).