Horatosphaga aethiopica, Massa, Bruno, 2015

Massa, Bruno, 2015, Taxonomy and distribution of some katydids (OrthopteraTettigoniidae) from tropical Africa, ZooKeys 524, pp. 17-44 : 22

Taxon classification Animalia Orthoptera Tettigoniidae

Horatosphaga aethiopica sp. n. Figs 17-21, 22-24

Material examined and depository.

Ethiopia, Omo river, El Dire 5°06'21.45"N, 36°51'08.77"E (950 m) 21.V.1939 (Expedition E. Zavattari) (♂ holotype, ♀ allotype, ♂ paratype); Ethiopia, Omo river, El Dire (950 m) 19.V.1939 (Expedition E. Zavattari) (♀ paratype); Ethiopia, Omo river, Calam 4°41'20.08"N, 35°39'58.46"E (370 m) 14.VIII.1939 (Expedition E. Zavattari) (♀ paratype)) (MZR).

Colour.

Yellowish (alive specimens may show different colour) (Figs 17, 22).

Description.

Male. Head and antennae: fastigium of vertex very narrow, furrowed above, separated from the tuberculated fastigium of frons. Eyes rounded, well projecting. Legs long. Fore coxae unarmed. Fore tibiae furrowed on upper margin, distinctly widening above tympanum, which is closed on inner and on outer sides, tympanic auricles inflated. Fore femora unarmed, fore tibiae with 11 spines plus 1 spur on inner and outer ventral margins, 1 spur on inner and outer dorsal margins, mid femora unarmed, mid tibiae with 14 spines on inner and outer ventral margins, plus 1 spur on each side and 1 spur on both sides of dorsal margins, hind femora unarmed, hind tibiae with many spines on ventral and dorsal margins and 3 spurs on each side. Thorax: pronotum little narrowing anteriorly, little raised posteriorly, anterior margin straight, posterior margin rounded, humeral sinus absent, lobes of pronotum rounded and low. Tegmina shorter than abdomen, with pointed apices, their web-like venation very simple, cross-veins of area MA are arranged in a parallel fashion, a bit arcuate in inner part (Fig. 21). Hind wings rudimentary and linked to metanotum. Stridulatory region of left tegmen short and inflated, stridulatory file composed of 20-25 widely spaced teeth, of different size (Fig. 24). Abdomen: tenth tergite greatly enlarged and completely concealing supra-anal plate, in lateral view similar to a raptor beak (Figs 18-20); sub-genital plate long, up-curved and deeply divided into two lobes reaching margin of the tenth tergite and curved a bit backwards at end (Fig. 19); styli absent. Cerci short, in-curved, with a small apical spine (Fig. 20).

Female. As the male, but tegmina reduced to two small overlapping scales, not exceeding first abdominal tergite, but showing a residual web-like venation (Fig. 22). Cerci conical and pointed. Ovipositor up-curved and provided with many denticles on upper and lower margins (Fig. 23).

Measurements.

See Table 2. Horatosphaga aethiopica is characterized by its very small size, compared to related species, in particular in the length of tegmina and ovipositor.

Diagnosis.

Concerning the affinities between this and related species, there are only three Horatosphaga with the male having the tenth abdominal tergite greatly enlarged and completely concealing the supra-anal plate, namely Horatosphaga ruspolii (Shulthess, 1898), Horatosphaga diminuta (Chopard, 1954) and Horatosphaga vicina (Chopard, 1954), all described from Kenya. Horatosphaga ruspolii has fully developed wings, while the other two have reduced fore wings and rudimentary hind wings. According to Ragge (1960) Horatosphaga ruspolii lives also in the eastern Ethiopia, in the area between Ethiopia and Somalia, and in Uganda. Its external genitalia are very variable, but appendices of the sub-genital plate are simply up-curved and shorter than those of Horatosphaga aethiopica sp. n. However, Ragge (1960) suspected that Horatosphaga diminuta could be a brachypterous form of Horatosphaga ruspolii , and considered also that Horatosphaga vicina could be a large form of Horatosphaga diminuta , that also Chopard (in Chopard and Mc Kevan 1954) considered almost an exact repetition of Horatosphaga vicina on a rather smaller scale. Horatosphaga aethiopica sp. n., which is smaller than the above three species (see Ragge 1960 and Table 2), differs from the previous species not only by its external male genitalia, but also by the high reduction of wings, mainly in the female, a character that forces individuals to an important isolation. The reduction of wings probably was also the cause for a very reduced stridulatory file. Regarding the reduction of the stridulatory file related to the wing reduction, it is possible that also Horatosphaga diminuta has a different stridulatory file compared to the fully developed wings of Horatosphaga ruspolii , and this should result in a different song, an important specific barrier.

Etymology.

The Latin name aethiopica is a female adjective meaning "living in Ethiopia".

Discussion.

In 1939, between March and September, Zavattari (1943) carried out an expedition to the territory of the Omo river in Ethiopia. During that trip, participants reached the northern part of the Turkana lake, where they collected also some Orthoptera . Among them there was the series of Horatosphaga specimens listed above. This new taxon is remarkably different from all related taxa. Indeed, in none of the species known till now, the tegmina of the female are so much reduced to two small scales, as in Horatosphaga aethiopica sp. n. Concerning the tribe Acrometopini , the characters of this Horatosphaga species and those of other related species as provided by Hemp (2011) and Hemp et al. (2010) modify and update the key in Ragge (1960) partially based on the ratio between the length of the pronotum to that of the tegmina.