Thetella Otte & Alexander, 1983

Desutter-Grandcolas, Laure, Anso, Jérémy & Jourdan, Hervé, 2016, Crickets of New Caledonia (Insecta, Orthoptera, Grylloidea): a key to genera, with diagnoses of extant genera and descriptions of new taxa, Zoosystema 38 (4), pp. 405-452 : 424

Genus Thetella Otte & Alexander, 1983

Thetella Otte & Alexander, 1983: 193 .

Burcus Gorochov, 1986a . Type species Burcus boklavae Gorochov, 1986a . Synonymy in Otte (1994a).

TYPE SPECIES. — Thetella oonoomba Otte & Alexander, 1983 by original designation.

EMENDED DIAGNOSIS. — Large and relatively thin, lightly coloured nemobiines. Head somewhat flattened dorsally. Fastigium not very wide, but slightly wider than scape; ocelli in flat triangle, all small, the median the smallest. Eyes small, not protruding; distance between margin of cheek and lower margin of eye more than eye mid width. Maxillary palpi not elongate; joint 5 slightly longer than joint 3, little and regularly widened toward apex, truncated apically. Pronotum transverse; DD anterior margin concave, posterior margin convex; LL rectangular, lower margin shorter than upper margin. Legs I and II thin; tibiae shorter than femora. TI with a large outer tympanum, no inner tympanum. TI and TII with two apical spurs. TIII shorter than FIII; three outer and two inner apical spurs; median spur the longest on outer side; inner spurs very long, the dorsal the longest, longer than half basitarsomere. TIII with three outer and two inner subapical spurs, all short and about the same size. Tarsi elongate, with long basitarsomeres. Abdomen setose. Cerci long.

Male. FWs short, reaching abdomen mid length. Venation faint, except MA and MP, located at the limit between dorsal and lateral fields. Stridulatory apparatus complete, but mirror not separate from short apical field; chords widely apart from each other; CuP lacking. Subgenital plate short; distal margin with an acute median process. Male genitalia with a very long and narrow pseudepiphallic sclerite, curved upward and bifid at apex; rami and ectophallic apodemes short and wide; dorsal cavity short and very narrow.

Female. FWs lacking. Subgenital plate transverse, deeply emarginate distally.Ovipositor long and straight; apex regularly narrowed, ventral valves somewhat concave; dorsal valves with a variable longitudinal crest, margins and crest somewhat crenulated.

VARIATION. — While all the specimens of Thetella examined have only two inner subapical spurs on TIII, one female which otherwise fits Thetella diagnosis has three inner subapical spurs. It is moreover thinner than Thetella , and its coloration is variegated yellowish brown and dark brown. It originates from the Mandjelia summit, far from any coast or river: the status of this female will have to be checked with additional material and data.

DISTRIBUTION. — Thetella is recorded from Australia ( Otte & Alexander 1983), Tahiti ( Gorochov 1986a as Burcus ), Hawaii ( Otte 1994b) and Vanuatu (LDG, pers. obs.). It is here newly reported from New Caledonia, where it has been found in many localities of Grande Terre, Île des Pins and Lifou (LDG, pers. obs., material in MNHN).

HABITAT. — Thetella lives in small cavities in alveolate rocks located along streams or on the coast, mostly uplifted corals ( Fig. 4G ). Along the sea, it hides in these cavities when the tide is high, and gets out at low tide, grazing algae on the rocks. Males can be heard singing from the small cavities.

Figures

FIG. 4. — New Caledonian Nemobiinae (Trigonidiidae):A, Bullita transversa Desutter-Grandcolas, 1997,Col d’Amieu, by day (Photo PG); B, Bobilla sp., specimen from Parc Provincial de la Rivière Bleue; C, Koghiella flammea Anso & Desutter-Grandcolas, 2016, from Bois du Sud, by day (Photo JA); D, Paniella bipunctatus Desutter-Grandcolas, 2016, female, from Grand Kaori; E, Paora sp., specimen from Dzumac; F, Thetella sp., from Lifou (Loyalty Islands), by day (Photo PG); G, uplifted calcareous substrate where Thetella sp lives, Loyalty Islands (Photo PG). Scales bar: 1 mm.