Metopomystrini Cadena-Castañeda, 2025

Cadena-Castañeda, Oscar J., Quintana-Arias, Ronald Fernando, Infante, Ivette Coque, Silva, Daniela Santos Martins & Tavares, Gustavo Costa, 2025, Studies on pygmy grasshoppers: On the current Metrodorinae sensu lato classification (Orthoptera: Tetrigidae) with emphasis on American and Malagasy taxa, Zootaxa 5597 (1), pp. 1-265 : 116-119

Tribe Metopomystrini Cadena-Castañeda , trib. nov.

Type genus: Metopomystrum Günther, 1939 .

Description. Body slender and small (8–11 mm.) ( Figs. 77, 78, 79, 81, 83, 84). Head exserted above pronotum; vertex expanded as a whole; medial carina of the vertex very weak, almost absent, not projecting forwards and not compressed; lateral carinae of the vertex continuous, not elevated. Anterior margin of the vertex rounded ( Figs. 77B, 78B, 80C) or acute ( Figs. 83B, 84B), fastigium of the vertex projects forward and forms a long horn ( Figs. 77D, 80B), and the dorsum of the horn a deep depression formed of joined fossulae ( Figs. 80C, 83B, 84B). Antennal groves located lower than the ventral margin of the eyes, with 15 segments. Scutellum very narrow; frontal costa long, with bifurcation above the lateral ocelli, between the eyes ( Figs. 77C, 80A, 83C). Eyes conspicuous, round (almost as long as wide), or ovoid (almost twice as long as wide), occupying a third or nearly half of the cephalic capsule in lateral view. Lateral ocelli placed between the middle part of the eyes, near the base from where each branch of the fascial carinae diverges; medial ocellus located close to the lower margin of the scutellum; palpi with last three segments flattened and first two segments short and nearly cylindrical ( Figs. 77C, 80A, 83C). Thorax. Pronotum slender; pronotal disc flat, dorsum of pronotum between the carinae smooth, median carina continuous from the anterior margin to the posterior apex, anterior margin straight and apex truncated or acute ( Figs. 77A, 78A, 79A, 81); lateral lobes of pronotum subtriangular, lower margin slightly projecting to the sides, directed slightly sidewards, with rounded apex ( Figs. 77B, 78B, 80C, 81B, 81D); humeral angle wide, obliquely concave; infrascapular area narrow and short in macropteran species, in apterous species wider and reaching near the apex of the pronotum in lateral view; lateral area arising on the dorsal undulation of the infrascapular area, with similar width and reaching the apex in lateral view ( Figs. 77A, 78A, 79A, 81A, 81C). Wings present or absent; if present, tegmina ovoid and hind wings reaching the pronotum apex ( Fig. 80F). Legs. Fore and mid femora moderately compressed, straight or slightly undulated; mid femur carinated above ( Figs. 80D, 80E); hind femur with black lower half, genicular and antegenicular teeth poorly or moderately developed ( Fig. 83D); first article of posterior tarsi as long as the third. Abdomen. Male: Eighth to tenth tergite moderately constricted dorsally, cerci conical and reduced ( Fig. 80G); penultimate sternite mid-sized, almost as long as subgenital plate, little rounded in lateral view ( Fig. 80G); subgenital plate triangular-shaped in ventral view, upcurved and apex with a mid-conspicuous triangular notch ( Fig. 80H). Female: epiproct lanceolate and pointed, with a medial groove only in the apical portion. Subgenital plate quadrangular or triangular with a small spine in the middle of the distal margin. Ovipositor with the upper valve wider than the lower valve, armed with medium-sized teeth.

Genera included. Metopomystrum Günther, 1939 only.

Distribution. Widely in the inter-Andean valleys of Colombia (most macropterous species), Amazonia, and Mata Atlantica (wingless species). There is a large distributional gap between these regions (Maps 1 and 2).

Remarks. This new monogeneric tribe includes Metopomystrum , a peculiar genus that differs from the other taxa of Neotropical Metrodorinae due to its unique characteristics. It could be confused with the Metrodorini because, in lateral view, the medial carina protrudes beyond the eyes in several genera, with lateral carinae forming more or less pronounced horns in frontal view. But Metopomystrini trib. nov. has the vertex as a whole expanded; the medial carina of the vertex is almost absent, suggesting an extension of the vertex in a state and configuration different from the Metrodorini . Additionally, in Metopomystrini trib. nov., the lateral lobes of the pronotum are slightly expanded towards the sides and rounded, and the scutellum is very narrow and not very pronounced in lateral view; the opposite occurs in Metrodorini .

Genus Metopomystrum Günther, 1939

Type species: Metopomystrum pehlkei Günther, 1939 , by original designation.

Remarks. Metopomystrum was described with two species, M. pehlkei Günther, 1939 (from Colombia) and M. apterum Günther, 1939 (from Brazil), and it remained that way for more than 70 years. Cadena-Castañeda & Cardona-Granda (2015) added three additional species, M. amazoniense Cadena-Castañeda & Cardona-Granda, 2015 , M. lilianae Cadena-Castañeda & Cardona-Granda, 2015 and M. brevifastigiata (this last species now located in the new genus Rehniatra gen. nov.). Recently, an additional species was included, M. muricense Silva & Skejo, 2017 , from Brazil ( Silva et al., 2017). Here, we describe a new species from the Colombian Andes. However, between each locality of each species, there are large distributional gaps, which will most likely reveal additional species or genera. A key to species is provided below.

Key to species of Metopomystrum (modified from Cadena-Castañeda & Cardona-Granda, 2015 and Silva et al., 2017)

1. Apex of the horn rounded in dorsal view ( Figs. 77B, 78B, 80C); in frontal view, the horn projects above the eyes for more than one-half of a compound eye height ( Fig. 77C). Tegmina and wings visible and surpassing the abdominal apex ( Figs. 77A, 78A, 79A)............................................................................................... 2

- Apex of the horn acute in dorsal view ( Figs. 83B, 84B); in frontal view, projecting above the eyes for less than one-half of a compound eye height ( Fig. 83C). Tegmina and wings not visible ( Figs. 83A, 84A).................................. 4

2. Fastigium curves upwards strongly at about 45º in relation to the vertex ( Fig. 77A). Costal margin to medial margin of tegmina yellowish; dorsal margin of pronotum yellow ( Fig. 77D).............................................. M. lilianae

- Fastigium curves upwards at about 30° in relation to the vertex and then straight forward ( Fig. 80B). Tegmina and dorsal margin of pronotum unicolor ( Figs. 78A, 80F).................................................................... 3

3. Tegmina ovoid, costal and anal margins progressively curving towards the apex ( Fig. 78A). Hind leg without whitish stripes ( Fig. 78C)................................................................................... M. pehlkei

- Tegmina lanceolate, anal margin tapering straight towards the apex, costal margin rounded, and as they converge, apex narrow and rounded ( Fig. 80F). Hind leg with a whitish stripe on the upper half of the hind femur ( Fig. 79)...... M. ankeri sp. nov.

4. Horn directed upwards, elevated in relation to pronotal disc for about one third of a compound eye height ( Fig. 83B); in lateral view, horn wide and with rounded apex ( Fig. 83A). Eyes in lateral view subtriangular. Lateral lobes of the pronotum unicolor ( Fig. 83A)............................................................................... M. amazoniense

- Horn directed almost completely forward, only slightly elevated above the compound eye; in lateral view, horn thin and with triangular apex. Eyes in lateral view rounded. Lower half of the lateral lobes of the pronotum cream-colored............. 5

5. Horn directed forwards, slightly downwards in its apex ( Fig. 84A), and the vertex wider and more rounded in dorsal and lateral views ( Fig. 84B)............................................................................. M. apterum

- Horn directed forwards, slightly upwards, vertex narrow and acute in dorsal and lateral view............... M. muriciense