Ochrilidia socotrae, Massa, Bruno, 2009

Massa, Bruno, 2009, New and less known Orthoptera (Insecta) from the island of Socotra (Yemen), Zootaxa 2132, pp. 53-64 : 59-63

Ochrilidia socotrae n. sp.

Material examined and types. Socotra , Ra’s Shoab 6.IV.2008, B.Massa within bushes of Heleochloa dura (113, 5Ƥ). 3 holotypus, Ƥ allotypus ( Figs. 20, 21 ) preserved in the Museo Civico di Storia Naturale of Genoa, paratypes in the coll. B.Massa, University of Palermo.

Previous records. Two species of Ochrilidia Stål, 1873 were previously known on Socotra , O. kraussi (Bolivar, 1913) ( Uvarov & Popov 1957) and O. gracilis nyuki (Sjöstedt, 1909) ( Jago 1977) . Concerning the latter, yet found only on the Hadibou Plain, it is generally associated with vegetation of humid zones; it is easily recognizable by its elongate vertex, temporal foveolae narrow and not visible from above, knee of hind femurs lacking black spot ( Jago 1977). As regards O. kraussi, Uvarov and Popov (1957) recorded it from the same locality and on the same plants where I found the specimens above listed on 2008; however, this taxon has been synonymized with O. geniculata (Bolivar, 1913) by Jago (1977) and also Mistshenko (1986) agreed with this synonymy. Uvarov and Popov (1957) pointed out that the specimens collected at Ra’s Shoab (2 males and 2 females) were smaller and shorter compared with specimens coming from Sahara, and with metazona as broad as long. When Jago (1977) revised Ochrilidia , examined the specimens preserved in the British Museum, but he did not list within material examined Socotra specimens quoted by Uvarov and Popov (1957). I was unable to identify Socotra specimens collected by me either following the key of Salfi (1931) or the key of Jago (1977). In the former case I tentatively identified them as O. rothschildi (Bolivar, 1913) , junior synonym of O. geniculata (Bolivar, 1913) , in the latter as O. geniculata , in a dubitative way. For the reasons below reported, I consider that they belong to one undescribed species, to some extent related to O. geniculata .

Description. Lower margin of temporal foveolae is visible from above, foveolae are 4 times longer than high, pronotum keels more or less parallel in the prozona and just diverging in the metazona, pronotum much rugose with impressed points, interocular distance less than 1/2 width of fronto-vertical part of head in front of eyes in males, 1/2 to 3/ 5 in females ( Figs. 22-24 ); antennae not very long, reaching the mesonotum in males, the hind margin of the pronotum in females. Tegmina exceed apex of the abdomen, showing marginal area narrow and much close to submarginal ( Fig. 25 ). A small black spot is present on the upper side of fore and mid femora. Lower inner lobe of knee of hind femora shows a black spot, covering from 1/4 to 1/3 of the lobe in males, more extended on all the lobe in females. The inner side of male hind femora bears ca. 120-130 stridulatory pegs. Hind tibiae violet. Tegmina exceed the apex of hind femora ca. 2.9-3.2 mm in males and 4.1-4.5 mm in females. Male cerci are just longer than epiproctus, subgenital plate is a little pointed ( Fig. 27 ). Epiphallus (terminology according to Jago 1977) with erect ancorae, in dorsal view upper lophal lobe (b) large, median lobe (c) long and inclined inwards, and lower lobe (d) triangular and well separated from c ( Fig. 29 ). In lateral view lobe c is just visible between b (pointed) and d (very much protruded), about twice length of b ( Fig. 30 ). Aedeagal valves are directed dorsally and obliquely.

Biometrics and comparison with O. geniculata . Socotra specimens resulted very small; I compared them with a long series coming from N Africa and Arabia and I found a very high reduction of the size. Tables 2 reports measurements of O. socotrae n. sp. compared with O. geniculata (specimens from Algeria, Tunisia, Libya and Arabia). My measurements of O. geniculata match those reported by Jago (1977) for gregarious populations. All pairs of data resulted statistically highly significant (test t of Student, P<0.0001). Additionally, I compared the ratio total length/length of tegmina ( O. socotrae : males 1.20 ± 0.07, females 1.21 ± 0.04; O. geniculata : males 1.11 ± 0.06, females 1.11 ± 0.05) and the ratio length of tegmina/length of hind femurs ( O. socotrae : males 1.65 ± 0.07, females 1.63 ± 0.04; O. geniculata : males 1.81 ± 0.10, females 1.76 ± 0.09). In both cases, I found statistically highly significant differences (test t of Student, P<0.0001 for all pairs, except length of tegmina/length of hind femurs for females, for which P=0.004).

O. geniculata shows comparatively longer antennae (in males they arrive between meso- and metanotum, in females to mid legs). Interocular distance is more than 1/2 width of fronto-vertical part of head in front of eyes in males, 3/ 5 in females. Tegmina are longer with wider marginal and submarginal areas ( Fig. 26 ), male stridulatory pegs are 130-140. The black spot of inner lobe of knee of hind femurs cover ca. half to 3/4 of the lobe in both sexes, rarely is lacking ( Jago 1977). Tegmina exceed the apex of hind femurs ca. 4.9-5.5 mm in males and 5.5-9.2 mm in females. Cerci are longer and exceed clearly the epiproct, subgenital plate is clearly pointed ( Fig. 28 ). In the epiphallus of O. geniculata , in lateral view the lobe b levels with c, lower lobe d is well developed and ca. twice length of b; in dorsal view the lobe b is not much developed and d is very close to c ( Jago 1977). Finally, in O. geniculata pronotum metazona is about as long as broad, not longer than broad, as reported by Uvarov and Popov (1957) for its synonymy O. kraussi ; thus, this character does not differ in O. socotrae .

Derivation of name: from the isle of Socotra .

Habits. Species of the genus Ochrilidia generally are associated with graminaceous plants; Ochrilidia socotrae n. sp. lives on Heleochloa dura linked to sand dunes of Ra’s Shoab, the East cape of Socotra , characterized also by the presence of Avicennia marina on the back of dunes. In April 2008 I found an abundant population, constituted only by adults; males stridulated and in a few cases I observed that they were moving closer to a female. When a male was much close to a female, it raised alternatively hind femurs, showing the black spot, which eventually may act as sexual recognition.

I would like to thank very much Francesco M. Raimondo, manager of the Botanical Garden of Palermo and of the expedition to Socotra , Luigi Guiglia, Ahmed Saeid Suliman, director of the Conservation Unity of the Socotra Archipelago Conservation and Development Programme, who faciltated visit and collecting on the island. I am indebted to Attilio Carapezza, who collected together me insects at Socotra , and Pietro Lo Cascio and Flavia Griti who sent me some specimens collected in the Socotra archipelago between 20th and 27th February 2009. I also thank very much Hendrik Devriese (IRSNB, Department Entomology, Bruxelles), who identified Paratettix subpustulatus and sent me interesting considerations. I also thank Maurizio Pavesi and Michele Zilioli for facilities and assistance during the study of specimens of La Greca’s collection preserved at the Museo Civico di Storia Naturale of Milan.

Figures

FIGURES 20 – 24. Ochrilidia socotra n. sp. 20: lateral view of the male; 21: lateral view of the female; 22: head and pronotum of the male from above; 23: pronotum keels of the female; 24: lateral view of the head of the female.

FIGURES 25 – 30. Ochrilidia. 25: tegmina of the male of O. socotrae n. sp.; 26: tegmina of the male of O. geniculata; 27: last sternite and cerci of O. socotrae n. sp.; 28: last sternite and cerci of O. geniculata; 29 - 30: epiphallus of O. socotrae n. sp. from above (29) and in lateral view (30).

Tables

TABLE 2. Biometrics (in mm) of Ochrilidia socotrae n. sp. compared to that of O. geniculata (Bolivar, 1913). Total length between head to apex of hind femurs.

Species and sex	Total length	Length of tegmina	Length of pronotum	Height of pronotum	Length of hind femurs	Height of hind femurs
Ochrilidia socotrae males (n=11)	18.5 ± 0.64	15.5 ± 0.90	2.95 ± 0.14	2.14 ± 0.20	9.36 ± 0.39	1.92 ± 0.09
Ochrilidia geniculata males (n=25)	20.72 ± 1.21	18.64 ± 1.47	3.47 ± 0.26	2.55 ± 0.16	10.31 ± 0.61	2.27 ± 0.10
Ochrilidia socotrae females (n=5)	26.3 ± 0.77	21.8 ± 0.60	4.54 ± 0.15	3.52 ± 0.11	13.4 ± 0.40	2.80 ± 0.07
Ochrilidia geniculata females (n=25)	32.41 ± 1.73	29.23 ± 2.05	5.92 ± 0.38	4.52 ± 0.41	16.6 ± 1.18	3.45 ± 0.27
Acknowledgements