Bioacoustics of Socotracris kleukersi

Description. In addition to the characters of the genus: Large but thin species, globally lightly coloured, but with a contrasted orange head ( Fig. 1 ). Head. Usual location of median ocellus distinct as a rounded area without setae. Legs. TIII inner serrulation: no spine before spur 1, 2–3 spines between spurs 1 and 2; 4–6 spines between spurs 2 and 3, 28–32 above spurs; outer serrulation: 3–6 spines before spur 1, 8–9 spines between spurs 1 and 2, 29–33 spines above the spurs. Basitarsomeres III more than twice as long as tarsomeres 3-III ; two rows of small spines dorsally, more or less set at mid length: 4–5 inner spines in male ( 5 – 6 in female), and 0–1 outer spine(s) in male ( 7 – 8 in female), in addition to distal spines, the inner apical spine not always present in male. Colouration. General coloration very light, even in living specimens ( Fig. 1 ). Head dorsum and inner part of the scapes orange; 4 faint brown lines on the vertex, and a faint lighter median line ( Fig. 2 A); base of fastigium marked with brown ( Fig. 2 A). Face and cheeks very light yellow ( Fig. 2 B); lateral margins of fastigium with thick, brown setae; face with two arcuate light brown lines ( Fig. 2 B), parallel to antennal pits, and joining on fastigium under a wide light yellow spot. Eyes black, their inner margin largely whitish. Maxillary palpi light yellow. Pronotum light yellow, marked with brown along anterior and posterior margins, and with light brown and ochre in the first half of dorsal disc ( Fig. 2 E). Lateral lobe almost entirely light yellow, except for light brown lower margin ( Fig. 2 C). Legs light brown; TIII spines and spur tips brown; FIII with short brown stripes on outer side, the knees partly orange brown ( Figs. 1 , 2 D). Sternites light yellow, including the subgenital plate in male and female. Meso- and metanota almost black in adults. Tergites light brown, their distal margins marked with brown; supra anal plate light yellow, the basal margin and in the female the distal margin marked with brown. Male: Metanotum ( Fig. 2 F) with a median pit filled with long, white setae; anterior and posterior margins raised. FWs not reaching distal margin of tergite 3. Stridulum ( Fig. 3 B): harp crossed by 9 main veins parallel and oblique. Stridulatory file with about 169 teeth, the teeth small and very closely set in outer part of the file. Lateral field as on Fig. 3 A. FWs dark brown, the middle of the harp lighter; veins brown or light yellow. Supra anal plate ( Fig. 4 I) wider than long, the distal angles slightly protruding. Subgenital plate ( Fig. 4 G–H) quite high and short, its distal margin largely concave. Male genitalia: Pseudepiphallic lophi very small. Pseudepiphallic parameres sclerotized on their distal and outer margins only. Ectophallic fold with a very long sclerite on its ventral side, this sclerite largely bifurcated in its anterior half. Endophallic sclerite median prong longer than the two lateral ones. Endophallic apodeme short, lamellar. Female: Meso- and metanota and tergite 1 very dark. FWs not reaching the distal margin of the metanotum ( Fig. 3 C); venation as on Fig. 3 C. Subgenital plate short; distal margin concave ( Fig. 4 J). Ovipositor shorter than FIII, as on Fig. 4 K. Female genitalia: Copulatory papilla small and apically rounded ( Fig. 4 D–F); sclerotization circular, wider ventrally than dorsally ( Fig. 4 F). Measurements (in mm). Male holotype : Pronotum length: 2,3. Posterior width of pronotum: 4. Maximal width of pronotum: 4,7. FW length: 6,2. FW width: 5,5. FIII length: 16. TIII length: 16,5. Length of hind basitarsomere: 4,8. Female allotype: Pronotum length: 2,7. Posterior width of pronotum: 4,6. Maximal width of pronotum: 5,3. FW length: 1,7. FIII length: 17,2. TIII length: 17,7. Length of hind basitarsomere: 5,1. Length of ovipositor: 15,5. Calling song. Unknown.

Distribution. Known from Socotra only. Up to now the species is only known with certainty from the type locality. One juvenile of possibly the same species as described here was collected in 2004 in Dilhaile Cave, Diksam Plateau, which is located at four kilometres from the type locality, during an expedition of the Socotra Karst Project (Dr. K. Van Damme, pers. comm.), but this requires further study. The specimen of Dilhaile Cave is depicted in Cheung and DeVantier (2006, p. 109) . The two sites are located in strongly karstified limestone and could possibly be connected through the limestone, which in turn would allow the species dispersion by subterranean network. Dr. K. Van Damme has observed a similar looking cricket as described here, calling deep inside Erhr Cave, Momi (pers. comm.). In 2009 RF visited some other caves: Hoq Cave ( N12.587731° E54.354516° ) at Momi Plateau and Dejub Cave ( N12.384925° E54.015684° ) in the southern edge of Diksam, but no crickets were found here. Habitat and life history traits. Specimens were found in a small cave situated in a cliff along the right bank of Wadi Zerik. The entrance of the cave ( Fig. 5 B,D) is facing southeast. Apart from some small, shallow pools at the entrance, the cave was rather dry at the time of the visits ( Fig. 5 C). The cave is approximately 30 m long and some 10 m high. Specimens sitting vertically on the walls were found after several meters from the entrance. On all three visits to the cave the species appeared to be numerous, occurring in tens of individuals. During the visit on 21.ii.2009 only nymphs were found. On both visits in November 2010 apart from tens of nymphs, several adults were present. No specimens were observed outside the cave. Because of the habitat, S. kleukersi n. sp. can be defined as troglobitic, which is confirmed by its very light colouration and reduced eyes. S. kleukersi n. sp. is predated by spiders ( Fig. 5 E). Potential other predators present at the type locality are bats ( Rhinopoma hardwickii ) and whip spiders ( Amblypygi : Charinidae ).