Acrotylus innotatus Uvarov, 1933

Acrotylus innotatus Uvarov, 1933 View in CoL

Figs 62 View Figure 62 , 63 View Figure 63 , 64 View Figure 64 , 65 View Figure 65 , 66 View Figure 66

References for Socotra.

Uvarov 1933: 267 [as Acrotylus insubricus innotatus ]; Ingrisch 1999: 359, figs 19–20, 66; Massa 2009: 57 [as Acrotylus insubricus ]; Wehrt 2021: 5–7.

Diagnostic notes.

Acrotylus innotatus differs from A. incarnatus as follows: in lateral view, A. innotatus has a step-like raised instead of a gently sloping first half of the prozona. The posterior margin of the pronotum is subrounded to slightly angular instead of rounded and the pronotum has a rugose instead of a smooth surface. The hind wings are basally pinkish-red instead of orange-red, as in A. incarnatus , although the difference can be subtle (Figs 63 View Figure 63 – 65 View Figure 65 ). A. innotatus has shorter mid-femora than A. incarnatus (Fig. 65 B View Figure 65 ).

Preliminary results of genetic analyses of the holotype of A. innotatus and several of our Socotran specimens confirm the identification of our Socotran material ( Wehrt 2021). Socotran specimens differ morphologically to some extent from the type specimens. The ratio of the prozona and metazona of the pronotum seems to be smaller (a relatively long metazona) compared to the type specimens. The darkening of the apical halves of the wings is less pronounced and sometimes hardly visible (Figs 63 View Figure 63 , 65 View Figure 65 ). However, these differences are likely to represent local variations.

Acrotylus innotatus differs from A. insubricus (Scopoli, 1786) as a former subspecies of the latter by a slimmer habitus, relatively longer tegmina and, most importantly, the absence of a dark band on the hind wings ( Uvarov 1933). The name innotatus , meaning unmarked, may refer to that character. A. insubricus does not occur on Socotra. Massa (2009) mentioned A. insubricus to be present on Socotra, referring to A. innotatus (as a former ssp. of A. insubricus ) (Massa, in litt).

Taxonomic notes.

Uvarov (1933) described Acrotylus insubricus innotatus , based on specimens collected in several countries: the Arabian Peninsula, Iran and Somalia. All are deposited in the NHMUK. The male holotype (Fig. 63 View Figure 63 ), together with 24 paratypes, was collected in the “ South Arabian Desert ” between 10 December 1930 and 5 February 1931 by Bertram Thomas during a camel journey from Dhofar ( Oman) to Doha ( Qatar) ( Thomas and Wyllie 1931; Uvarov 1933). When Uvarov first saw Thomas’ specimens, he thought they belonged to A. incarnatus from Socotra. Only after studying the type of that species did Uvarov (1933) realise incarnatus is more closely related to longipes , while Thomas’ specimens were closer to Acrotylus insubricus (Scopoli, 1786) . We found several specimens of A. innotatus identified as incarnatus in Popov’s material from Socotra collected in 1953 (Uvarov in Uvarov and Popov (1957)). When working out the Socotran material, Uvarov probably did not have innotatus in mind anymore. Finally, Ingrisch (1999) raised A. insubricus innotatus to a full species, based on three specimens collected in Yemen in 1996 and 1998.

After examining the specimens, based on which Ingrisch raised A. insubricus innotatus to a full species, we conclude they do not belong to A. innotatus . Ingrisch (1999) stated that innotatus has a “ distinctly different pronotum ” from insubricus . After studying the type series, the pronotum, in reality, appeared much like that of A. insubricus , especially the step-like raised frontal half of the prozona (Fig. 64 D View Figure 64 ). Drawings of the pronotum of the specimens from mainland Yemen in figs 19, 20 on p. 372 in Ingrisch (1999) do not show a step-like raised frontal half of the prozona and only display the principal sulcus, no secondary one. In the holotype of A. innotatus , the pronotum in lateral view is precisely like Ingrisch’s drawing of insubricus (fig. 18, p. 372).

Re-description.

Since Uvarov (1933) gave a limited species description and Ingrisch (1999) raised the taxon to the species level, based on specimens belonging to a different species, we provide a short re-description based on the type material. Apart from the characters already mentioned by Uvarov (1933), A. innotatus is characterised by a step-like raised anterior half of the prozona in front of the first transverse sulcus (Fig. 64 D View Figure 64 ). The pronotum has a well-pronounced median carina cut / impressed by two sulci, the mentioned first transverse sulcus and the principal sulcus. The dorsal part of the pronotum is strongly sculptured. The posterior margin of the pronotum is subrounded (Fig. 64 A View Figure 64 ). The base of the hind wing is pinkish-red with a more or less darkened (infumated) apical half and dark spots are present on the apex of the hind wing (Fig. 63 View Figure 63 ).

Distribution and occurrence.

Based on the type series of A. innotatus , the species occurs from Somalia through the Arabian Peninsula into Iran. Future studies could show that the actual distribution of the species is more restricted than that, as several paratypes from Somalia and Iran might represent other species. Hemp and Rowell (2020) state that A. innotatus only occurs in Arabia.

On Socotra, the species is restricted to the eastern part of the island, occurring on the limestone plateaus of Dixam and Momi and in the Hagher (Fig. 66 View Figure 66 ). Due to the superficial resemblance with incarnatus , it is probably overlooked.

Habitat and biology.

Uvarov (1933) considered A. insubricus innotatus as “ restricted to the driest deserts ” despite missing information about the collecting sites’ habitat. On Socotra, it occurs from 25–1450 m a. s. l. in a variety of habitats, mainly in high shrubland with succulents, Frankincense and Dracaena woodland and forests, submontane shrubland and grassland and montane mosaic. Records are from all seasons.

Bioacoustics.

Members of the Oedipodinae subfamily emit quiet, buzzing sounds during rivalry. From the genus Acrotylus , the sounds resemble the noise created by squabbling house sparrows, Passer domesticus ( Roesti and Keist 2009) . On Socotra, sounds have not been recorded.