Ochrilidia socotrae Massa, 2009

Felix, Rob, Bouwman, Jaap, Odé, Baudewijn, Ketelaar, Robert, Pham, Duc Minh & Bailey, James, 2025, The grasshoppers and crickets (Orthoptera) of the Socotra Archipelago (Yemen): a comprehensive overview and a description of a new Oecanthus Tree Cricket (Oecanthidae), Contributions to Entomology 75 (1), pp. 21-166 : 21-166

Ochrilidia socotrae Massa, 2009

Figs 49 , 50 , 51 , 52 , 53

References for Socotra.

Popov (in Uvarov and Popov (1957)): 379 [as Ochrilidia kraussi ]; Jago 1977: 180 [as Ochrilidia kraussi ]; Wranik 2003: 324, plates 153, 158 [as Ochrilidia gracilis ]; Massa 2009: 59–63, figs 20–25, 27, 29, 30.

Diagnostic notes.

Ochrilidia socotrae can be separated from O. gracilis nyuki by a shorter protruding fastigium of the vertex: the length in front of the eyes is equal to the width of the vertex at the frontal edge of the eyes, in dorsal view. The inner lower lobe of the hind knee has a black dot.

Taxonomic notes.

Popov collected four Ochrilidia specimens at Shuab in 1953 (Fig. 51 ) and identified these as O. kraussi (Bolívar, 1913) (Popov in Uvarov and Popov (1957)). However, he mentioned some differences with O. kraussi specimens from different African sites. These differences are mainly in the shape of the metazona of the pronotum: in the Socotran specimens, it is as long as wide, while in other kraussi specimens, it is often longer than wide. Specimens of O. kraussi from Somalia resemble the Socotra taxon (Popov in Uvarov and Popov (1957)).

In his revision of the genus Ochrilidia, Jago (1977) synonymised O. kraussi with O. geniculata , including Popov’s specimens of Socotra. Jago (1977) erroneously listed the four Socotran specimens under Ethiopia instead of Yemen. Massa (2009), therefore, was misled when he interpreted Jago as not having studied the Socotran specimens.

Massa (2009) described O. socotrae , based on specimens he collected at Shuab in 2008, the same site where Popov collected his specimens. He mentioned the following characteristics of O. socotrae that separate this taxon from O. geniculata from Africa and Arabia: overall smaller, shorter wings, a less marked black spot on the inner side of the hind knees, a less pointed subgenital plate, shorter cerci and less stridulatory pegs.

According to Massa (2009), the length and width ratio of the metazona does not differ between socotrae and geniculata , contrary to Popov’s statement about kraussi (in Uvarov and Popov (1957)).

After comparison, Popov’s specimens belong to O. socotrae , which is unsurprising since they come from the same site and habitat.

Distribution and occurrence.

Ochrilidia socotrae is endemic to Socotra. This species has only been found on three sites in coastal dunes near the two outermost capes of Socotra, Shuab and Neet in the west and Erisseyl in the east (Fig. 52 ). The species can be common in suitable habitat.

Habitat and biology.

O. socotrae is strictly associated with Urochondra setulosa (syn. Heleochloa dura ) (Popov in Uvarov and Popov (1957); Massa 2009). These grasses grow in narrow fringes of coastal dunes at an elevation of 0–10 m a. s. l. (Figs 2 , 3 ). Adults are found year-round and nymphs are found in February and November (Popov in Uvarov and Popov (1957); Massa 2009).

Ochrilidia gracilis and O. kraussi are intermixed in Wranik (2013): O. gracilis is mentioned as occurring in Heleochloa dura in Shoab and O. kraussi is mentioned as occurring elsewhere in Arabia in wet grasslands. The reverse is true. The former occurs in humid grasslands (also on Socotra; ssp. nyuki ), while the latter, as O. socotrae , occurs in U. setulosa ( H. dura ) vegetation.

Bioacoustics.

The calling song consists of 20–30 syllables repeated at 3–4 per second. Syllables last 90–110 ms and consist of a short, sharp tick-sound of about 25 ms followed by a weaker rustling sound (Fig. 53 ). The tick-sound is probably linked to the upward movement of both hind legs. During interaction with other males, a series of syllables may be shorter or may lead to the production of alternating syllables of the males involved. Additionally, some weaker shortly buzzing sounds can be heard, possibly linked to situations where a female is close to the male.

The same syllabic structure can be found in the song of Ochrilidia sicula (Salfi, 1931) (Baudewijn Odé, XC 846260, accessible at https://www.xeno-canto.org/846260) and O. pruinosa Brunner von Wattenwyl, 1882 ( Willemse et al. 2018). However, in the latter species, the syllables are adjoined in a dense echeme.

Figures

Figure 2. Salt marsh with Arthrocnemum macrostachyum and Aerva javanica. The salt marsh, separated by a coastal dune with Urochondra setulosa, is the typical habitat of Heteracris adspersa. Neet, Socotra, 28 Oct 2010 (photograph Rob Felix).

Figure 3. Coastal coralline sand sheet with the grass Urochondra setulosa. Habitat of Ochrilidia socotrae and Acrotylus incarnatus; on patches with coarser coralline gravel, Sphingonotus ganglbaueri occurs. Erisseyl, Socotra, 3 Nov 2010 (photograph Rob Felix).

Figure 49. Ochrilidia socotrae Massa, 2009, male. Neet, Socotra, 28 Oct 2010 (photograph Robert Ketelaar).

Figure 50. Ochrilidia socotrae Massa, 2009, female. Erisseyl, Socotra, 3 Nov 2010 (photograph Robert Ketelaar).

Figure 51. Ochrilidia socotrae Massa, 2009, male. Collected by George Popov at Shuab, Socotra, in 1953. Scale bar: 1 cm (photograph Rob Felix).

Figure 52. Distribution of Ochrilidia socotrae Massa, 2009 in the Socotra Archipelago.

Figure 53. Calling song of Ochrilidia socotrae Massa, 2009. Oscillograms depicting 10 s (A) and 500 ms (B). Neet, Socotra, 28 Oct 2010, 13: 42 h; RecRF 10112; SpRF 10 YE 020–024; XC 877885, accessible at https://www.xeno-canto.org/877885.