Trigonidium Rambur, 1838

Hegg, Danilo, 2024, Small crickets of New Zealand (Orthoptera: Grylloidea: Trigonidiidae and Mogoplistidae), with the description of two new genera and species, European Journal of Taxonomy 955 (1), pp. 1-87 : 57-58

Subgenus Trigonidium Rambur, 1838

Trigonidium Rambur, 1838: 39 .

Trigonidomorpha Chopard, 1925: 40 syn. nov.

Trigonidomorpha – Chopard 1968: 328. — Otte & Alexander 1983: 222. — Desutter-Grandcolas et al. 2016: 416. — Tan et al. 2019: 577–578. — Rentz & Su 2019: 316.

Trigonidium – Otte & Alexander 1983: 225–227, fig. 177, table 15.

Trigonidium (Trigonidium) – Gorochov 1987: 5–17. — Rentz & Su 2019: 303. — Tan et al. 2019: 573–587.

Trigonidiomorpha [sic] – Baehr 1989: 20.

Trigonidium (Trigonidomorpha) – Otte 1994: 46. — Gorochov et al. 2018: 317.

Type species

Trigonidium cicindeloides Rambur, 1838 by original monotypy.

Amended diagnosis

Small trigs, body length <6 mm; body black with yellow legs, or entirely yellow, or in between. Eyes large and bulging, facing forwards. Short stridulum present on right tegmen in males, not used to generate any sound. Adults come in two morphs, wingless and winged. In wingless morph, tegmina rounded in lateral profile, thin, transparent, appressed to the abdomen; hindwings absent. Auditory tympana absent. In winged morph, tegmina thick and coloured yellow-brown; hindwings present, although they might be chewed off or dropped after a few days. Auditory tympana present on both anterior and posterior sides of Tibia I, the anterior tympana larger than the posterior ones. Intermediate morphs (i.e., wingless with reduced tympana, or winged without tympana) possible but rare.

Etymology

Meaning unknown; not explained by Rambur (1838). Trigonidium is neuter gender.

Measurements

See Table 7 .

Habitat and ecology

Diurnal, predatory crickets; living primarily in meadows with tall grass, although occasionally found in the foliage or on the flowers of shrubs. While the New Zealand species is not known to produce any sound, the European species Trigonidium (Trigonidium) cicindeloides generates sound by rubbing the spurs of the last two segments in the maxillary palpi against one another ( Ingrisch 1977).

Distribution

New Zealand, country-wide except for Rakiura/ Stewart Island and subantarctic islands. Also Australia, tropical and subtropical Asia, Africa and Europe.